THE UNIVERSITY OF ILLINOIS LIBRARY 1 64-1 . / • Jl8t 4 REMOTE STORAGE Return this book on or before the Latest Date stamped below, A 1 charge is made on all overdue books. U. of I. Library JUL lb4U HP -6 isa i RFH 25 Si' dPii -2 IjB5 NOV -71? rt & nr-!--*;. \ 1468S-S t' i C'- (. Digitized by the Internet Archive in 2017 with funding from University of Illinois Urbana-Champaign Alternates https://archive.org/details/technologyofbreaOOjago THE TECHNOLOGY OF BREAD-MAKING By one of the same Authors, Inorganic Chemistry, Theoretical and Practical. With 49 Woodcuts and Questions and Exercises. Crown 8vo, 2s 6d, London : Long- mans, Green & Co An Introduction to Practical Inorganic Chemistry. Fcap. 8vo, Is. 6d. London: Long- mans, Green & Co. Inorganic Chemistry. A Manual for Students in Advanced Classes. With Plate of Spectra and 78 Woodcuts. Crown 8vo, 4s. 6d. London : Longmans, Green & Co, Introduction to the Principles of Bread- Making. ,^2s. London : Maclaren & Sons, 37— 38, Shoe Lane, E.C. Cantor Lectures on Modern Develop- ments of Bread-making. Is. London : Society^ of Arts, John Street, Adelphi. Cantor Lectures on Chemistry of Con- fectioners’ Materials and Processes. Is. Lon- don : Society of Arts, John Street, Adelphi. Forensic Chemistry and Chemical Evidence. 5s. London : Stevens & Haynes, Bell Yard, Temple Bar. THE TECHNOLOGY OF BREAD-MAKING INCLUDING The Chemistry and Analytical and Practical Testing of Wheat, Flour, and other materials employed in Bread-making and Confectionery. By WILLIAM JAGO, F.I.C, F.C.S., Of Lincoln’s Inn, Barrister-at-Law ; Senior Examiner in Bread-making and Confectionery to the City and Guilds of London Institute for the Advancement of Technical Education ; Cantor Lecturer on “ Modern Developments of Bread-making,” and “ Chemistry of Confectioners’ Materials and Pro- cesses ” to the Society of Arts, London, etc. And WILLIAM C. JAGO, Food Manufacturing Chemist. AMERICAN EDITION. BAKERS’ HELPER COMPANY, CHICAGO, 'v Copyright] [All Rights Reserved. 6 1 1 REMOTE SrOiwi L. & A. Harris, Printers, 94, Leadenhall St., E.C. PREFACE. The volume now offered to the reader must be regarded as a development of the vTiter’s former works on the same subject, which appeared in 1886 and 1895. The general mode of treatment is, therefore, to some extent governed by that of its predecessors. It should be remembered that the requirements of the student of the technology of bread-making, whether miller or baker, have been the first consideration ; and accordingly the arrangement is that which seems most likely to be of service and assistance to him. In addition the authors have endeavoured to make the book as complete a work of general reference as possible. In the preparation of the present treatise the wTiter has had the benefit of the assistance of his son, Mr. William C. Jago, whose name, together with his ^ own, appears on the title-page. Mx. William C. Jago’s wide experience of ' the practical application of chemical methods in the mill and the factory r have been of much advantage. So also has been his knowledge of the dairy- ing industries gained in Denmark, and of modern biology and bacteriology acquired in the laboratories of Professor Jorgensen in Copenhagen. The writer is further indebted to him for the investigation and verification of many references in the original French, German, and Danish. Since 1895 much valuable original work has been done in this country, ^ and also in Europe and America, on bread-making and cognate subjects. The authors have tried to place this as fully as possible on record. In so doing they have adopted the method of giving a resume of each investiga- - tor’s work and conclusions, following the same where necessary by any j 7 comments of their own. In pursuance of this plan, new chapters have been i wTitten on the Strength of Flour, the Bleaching of Flour, Wheat Flour and ] Bread Improvers, the Nutritive Value and Digestibility of Bread, and the I Weighing of Bread. Subjects such as “ Standard ” Bread, and the use of V 199817 PREFACE. additions to flour and bread have been critically and exhaustively examined. The application of chemical and other tests to routine mill practice has been dealt with in a special chapter. Following on the inclusion of Confectionery in the programme of the City and Guilds of London Institute for the Advance- ment of Technical Education, a chapter has been added on the Chemistry of the Confectioners’ Raw Materials and Processes. Again, the authors desire to express their thanks to the number of millers, bakers, and scientists who by personal communications and in many other ways have rendered them so much assistance in the preparation of this volume. The numerous instances of help of this kind will be evident on a perusal of the following pages. In a work of such magnitude, the authors cannot hope to have alto- gether avoided mistakes, and in such cases they confldently appeal to the generous consideration of their readers. WILLIAM JAGO. London, E.C., 1, Garden Court, Temple, July, 1911. CONTENTS CHAPTER PAGE I Introductory .......... [I Description of the Principal Chemical Elements, and their In- organic Compounds Ill Description op Organic Compounds ...... [V The Microscope and Polarisation op Light . . . . V Mineral and Fatty Matters ....... VI The Carbohydrates ......... VII' The Proteins .......... VIII Enzymes ane Diastatio Action ....... IX Fermentation .......... X Bacterial and Putrefactive Fermentations . . . ■ XI Technical Researches on Fermentation . . . . . XII Manufacture of Yeasts XIII Physical Structure and Physiology ^of the Wheat Grain . XTV Chemical Composition of Wheat ...... XV The Strength op Flour ........ XVI Chemical Composition of Flour and other Milling Products XVII The Bleaching of Flour ........ XVni Bread-making .......... Special Breads and Bread-making Processes .... vii 1 2S 41 57 68 74 91 120 145 182 108 232 254 270 291 344 375 400 483 XIX TIU CONTENTS. OHAPTKR PAGE XX Wheat, Flour and Bread Improvers . . . . .497 XXI The Nutritive Value and Digestibility of Bread . . . 625 XXII The Weighing of Bread . . . . . . , . 562 XXIII Bakehouse Design ......... 681 XXTV The Machine Bakery . . . . . . . .612 XXV Analytic Apparatus . . . . . . . . .680 XXVI Commercial Testing of Wheats and Flours .... 689 XXVII Determination of Mineral and Fatty Matters . . . 757 XXVIII Soluble Extract, Acidity and Proteins . . . . .768 XXIX Estimation of Carbohydrates . . . . . . . 800 - XXX Bread Analysis . . . . . . . . .831 XXXI Adulterations and Additions . . . . . . .837 XXXII Routine Mill Tests . . . . . . . . .844 XXXIII Confectioners* Raw Materials ....... 852 Index ........... 894 THE TECHNOLOGY OF BREAD-MAKING. CHAPTER I. INTRODUCTORY. 1. General Scope of Work. — ^The object of the present Work is to deal, in the first place, with those branches of knowledge which together con- stitute the scientific foundations of Bread-making as a science in itself. Paramount among these is — Chemistry. With which is closely associated — Heat and its properties. Fermentation and the Biology of Micro-organisms. Vegetable Physiology in its relation to the Wheat Plant. Microscopy. Next, viewing Bread-making as an Art or Industry, the design of Bakeries and adaptation of Machinery for various purposes is discussed. Following on this is a description of the various processes and operations involved in the Commercial Manufacture of Bread, together with an investigation of the many important practical problems connected therewith. Chapters are also added on the nutritive value, and weighing, of bread, and other matters of interest. The more purely analytical section of the work includes detailed diiections foi the commercial testing and valuation of flour, yeast, and other bread-making materials ; in addition to which there are also given approved methods for the commercial and complete chemical analysis of such substances. A number of analyses and other chemical investi- gations have been recently made for the purposes of this book, and are here for the first time published. The work concludes with a description of the chemistry of confectioners’ raw materials. It is not proposed to adhere to any very rigid classification but so to arrange the subject matter as seems most likely to meet the requirements of the majority of readers. 2. Matter. — The bodies with which we are surrounded present an almost endless diversity of colour, appearance, and other characteristics. One property they however all possess in common, and that is the property of weight. All bodies are attracted by the earth, and any substance is said to be heavy because of the resistance which it offers to this earth-attrac- tion or gravitation. Not only are solid bodies, such as iron and wood, possessed of weight, but so likewise are liquids, such as water and oil, and also gases, such as, for example, common air, or coal-gas. It is conveni- ent to have one name for all bodies which possess weight, and for this pur- pose, in English, the term Matter is employed. Matter, then, is anything 1 ' B 2 THE TECHNOLOGY OF BREAH-MAKING. which possesses weight (i.e., is acted on by gravitation), and exists in three distinct forms, namely, as solids, liquids, and gases. 3. Force. — The definition of matter just given would seem at first sight sufficiently comprehensive to embrace everything of which we can take cognisance, but yet a moment’s reflection shows the existence of other things beside matter. An illustration best demonstrates this fact — A hammer-head is known to consist of matter because it possesses weight ; but if with this hammer-head you give a series of blows to a small piece of nail -rod, you have given the nail-rod something which is not matter. The hammer-head is not lighter, nor is the nail-rod heavier — still the blows are something, as otherwise they could produce no effect. For one thing, the nail-rod will have been flattened and altered in shape ; further, and which is of far more present importance, it will have become hot to the touch. Again, to make use of another illustration, if a dry brick be care- fully weighed and then made red-hot in a furnace, it will be found to weigh when hot precisely the same as it did when cold. Further, this brick, if allowed to become cold, imparts heat to surrounding objects, and never- theless remains unaltered in weight. Here, then, is something very definite which a body can receive and again yield, and which is not matter. This something has, however, a very direct relation to matter ; in the first illustration the blows were struck by the moving hammer-head, which consists of matter in motion. The more rapid the motion, the more violent would be the blows ; in fact the force of the blow depends both on the quantity of matter and the rapidity of its motion. A number of con- siderations lead to the belief that the hot iron of the nail-rod and also the hot brick differ from the same substances in the cold state, in that their component particles are in a state of movement ; as these substances cool, the particles once more enter into a condition of comparative rest. This something beyond matter is closely associated with motion, and is termed force. Force is defined as that which is capable of setting matter in motion, or of altering the direction or velocity of matter already in motion. The motion of bodies may be divided into two classes : there is, first, that of the body as a whole, as in the case of the moving hammer-head ; second, the internal movements of the particles of a body, as when it becomes hot. Elements of Heat. 4. Heat, its Nature and Effects. — Among generally observed facts with regard to heat, one of the first and most important is that it induces the sensation of warmth. According to the character and degree of this sensa- tion, a body is said to be cold, warm, or hot. The conditions which pro- duce this sensation of warmth also cause other well-marked changes in the physical condition of substances. The general effects of heat are to cause bodies as they get hot to expand in volume ; further, solids are re- duced to the liquid state ; and, with still further increments of heat, liquids are converted into gases. The opposite series of changes occur as heat is abstracted from bodies. From the explanation of Force given in the pre- ceding paragraph, it will be understood that these changes are not accom- panied by any addition or diminution of weight. On the contrary. Heat is viewed as a form of Force, and is regarded as a mode or variety of internal motion of the particles of bodies — the hotter they are, the more violent and energetic is this motion. 5. Measurement of Heat : Temperature. — The earliest and most accessible measure to be applied to heat is that of the sensation of warmth before referred to, and according to whether a boiy to the touch is hot or cold, it is said to be of high or low temperature. Temperature is, in fact, the mea- INTRODUCTORY. 3 sure of what is popularly termed “how hot a body is ; ” it will be seen on consideration that this depends on the power the body has of imparting heat to another body. Thus, if when the hand is thrust into water, the water is able to yield heat to the hand, it is said to be “hot,” while if it robs the hand of heat it is said to be “ cold.” The measure of this power is termed temperature, and is more exactly embodied in the following definition : — The temperature of a body is a measure of the intensity of its heat, and is further defined as the thermal state of a body considered with refer- ence to its power of communicating heat to other bodies. 6. The Thermometer. — ^For scientific, and also for most technical, purposes, the sensations are not sufficiently accurate methods of measuring tem- perature ; accordingly temperature is usually measured by certain of the effects which heat produces : the most convenient for this purpose is the expansion of liquids with an elevation of temperature. For the general purposes of temperature measurement, the metal mercury is the most convenient substance. This liquid, enclosed in a suitable vessel, constitutes the temperature-measuring instrument termed a thermometer. In constructing a thermometer, a bulb is blown at one end of a glass tube of very narrow bore ; the bulb and tube are next filled with carefully purified mercury ; this is boiled, and thus all air and moisture are driven out of the tube ; the open end is then hermetically sealed by fusing the glass itself. At this stage the bulb and a portion of the tube are filled with mercury, the remainder of the tube being a vacuum, save for the presence of a minute quantity of mercury vapour. On heating the bulb of this - instrument, the mercury expands and rises considerably in the stem. Throughout any body, or series of bodies in contact with each other, heat lias a tendency so to distribute itself that the whole series shall be at the same temperature ; consequently if the thermometer be placed in contact with the body whose temperature it is desired to measure, a redistribution of heat occurs, until the two are at the same temperature. That is to say, if the body be the hotter, it yields heat to the thermometer ; and if it be colder, it receives heat from the thermometer, until the temperature of both is the same. The two being in efficient contact, this stage is indi- cated by the mercury becoming stationary in the thermometer. Now the volume of mercury is constant for any one temperature ; therefore, to register temperature, it is only necessary to have further a scale, or series of graduations, attached to the stem of the instrument, by which the temperature may always be read. 7. The Pyrometer. — ^The ordinary mercury thermometer is not well adapted to the measurement of comparatively high temperatures, since the mercury boils at a temperature considerably below that of a dull red heat. In consequence other instruments have been devised for that purpose, to which the name of pyrometers has been given. The pyrometer may therefore be regarded as a high temperature thermometer. The pyrometers used for measuring the temperature of some types of bakers’ ovens, consist usually of a rod and casing constructed of materials which expand at different rates with an increase of temperature. The differential expansion actuates a needle moving in front of a dial plate. 8. Thermometric Scales. — Subject to certain precautions, the tempera- tures of melting ice and of steam in contact with boiling water are con- stant. The height at which the mercury stands when immersed in each of these is marked on most thermometers ; for the registration of other temperatures some system of graduation must be devised. The one most commonly employed in this country is that of Fahrenheit, while for scien- 4 THE TECHNOLOGY OF BREAD-MAKING. tific purposes that of Celsius, or the Centigrade Scale, is almost universally adopted. Fahrenheit divided the distance between the melting and boiling points of his thermometer into 180 degrees ; degrees of the same value were also set off on either side of these limits. At 32 degiees below the melting point he fixed an arbitrary zero of temperature, from which he reckoned. On his thermometric scale, the melting point is 32°, while the boiling point is 32 + 180 = 212°. Degrees below the zero are reckoned as — (minus) degrees, thus —8° means 8 degrees below zero, or 40 degrees below the melting point ; degrees above 212 simply reckon upwards, 213, 214° F., etc. The Centigrade Scale is much simpler, the melting point is taken as 0° or zero, and the boiling point as 100° ; temperatures below the melting point are reckoned as — degrees. The conversion from one to the other of the Centigrade and Fahren- heit Scales may be easily performed. 180 Fahrenheit degrees = 100 Centigrade degrees. 0 — 5 U 5 5 5 5 ^ 5 5 5 5 1 ,, degree = ,, degree. ."> 5 5 5 5 ■ 1 5 5 5 5 There is this important difference between the two scales — Centigrade degrees count from the melting point, while Fahrenheit degrees are reckoned from 32 below the melting point. 30° C. = 30 X 5 = 54 Fahrenheit degrees. Therefore 30° C. are equivalent to 54 Fahrenheit degrees above the melting point, but as the melting point is 32, that number must be added on to 54 ; the temperature Fahrenheit equal to 30° C. is 86°. By the reverse operation, Fahrenheit degrees are converted into degrees Centigrade. The following formulae represent the two operations : — C°.X (P°.-32)x5^^o The following table gives the equivalent readings on the two thermometric scales for some of the most important temperatures — -40° C. = -40° F. 70° C. — 158° F. -17*7 ? 9 0 99 75 167 , , 0 9 9 32 99 80 ,, = 176 9 9 15 ’ 9 59 9 9 85 „ 185 9 9 15-5 9 9 60 90 „ 194 9 9 20 68 9 9 1 93-3 ,. zzn 200 2M -— 70 9 9 95 ,, 203 9 9 25 77 9 9 100 „ — 212 9 9 26-6 9 9 80 9 9 150 „ 302 9 9 30 86 99 1 200 „ 392 9 9 35 — 95 232*2 = 450 9 9 37-7 9 9 100 9 9 250 !! 482 9 9 40 9 5 104 260 „ = 500 9 9 45 9 9 113 9 9 287*7 „ 550 9 9 50 9 9 122 300 „ — 572 9 9 55 131 9 9 316*6 ,, 600 9 ' 60 9 9 140 9 9 ! 350 „ 662 9 9 65 9 9 149 99 1 400 „ 752 9 J 9. Quantity of Heat. — Temperature is not a measure of quantity of heat, for a thermometer would indicate the same temperature both in a vessel containing a pint, and one containing a gallon of boiling w^ater, al- though it is evident that one must contain eight times as much heat as INTRODUCTORY. 5 the other ; further, to raise the gallon of water to the boiling point, eight ^mes the amount of heat necessary to similarly raise the pint is required. This leads to the mode of measuring and registering quantity of heat. Quan- tity of heat is measured by the amount necessary to raise a certain weight of some body from one to another fixed temperature. The amount of heat necessary to raise 1 gram of water from 0° to 1° C. is termed a Unit of Heat. For the phrase Unit of Heat, a distinctive term, “ Calorie ” is now fre- quently employed From this it follows that to raise 2 grams of water from 0 to 1 C. will require 2 Units of heat, or 2 H.U., or 2 Calories. Be- freezing and the boiling points, ap'proximately the same amount 01 heat IS necessary to raise 1 gram of water through any 1 degree of tem- perature, so that to raise 1 gram through 2 degrees will require approximately 2 H.U. For practically all purposes, it may be taken that the weight of water in grams X degrees of temperature through which it must be raised — the number of H.U. required. 10. Specific Heat.— The quantity of heat necessary to raise the same V eight of different substances through 1 degree of temperature varies very considerably. The quantity of heat necessary to raise) 1 gram of any sub- stance through 1 degree of temperature is termed its SpeciBc Heat. Prom this definition it follows that the specific heat of water at 0° C is I'OO or unity. The following table gives the specific heat of various substances’;— Substance. Water Alcohol Glass Iron . . Copper Mercury Specific Heat. 1-00000 0-61500 0-19768 0-11379 0-09391 0-03332 If equal weights of water at different temperatures are mixed together the result is a mixture having a temperature the mean of the two • thus a gallon of water at 20° C. mixed with a gaUon at 50° C. will produce a mixture at the temperature of 35° C. But if equal weights of two sub- stances of different specific heats be thus mixed, the temperature of the mixture of the two will not be a mean of those of the substances, but will be nearer that of the substance having the higher specific heat. The most important mixture with which the baker has to do is that of flour with water, as the temperature of the resultant dough is a matter of vital con- cern to him The results are complicated by the presence of other ingre- dients, as salt and yeast, and also in practice by loss of heat through absorp- tion by the surroundings of the dough, and heat generated by chemical action among the ingredients. The following are the results of laboratory experiments made by mixing together flour and water only, and carefully taking the temperatures, but not allowing for loss of heat absorbed bv containing vessels. ^ 500 grams of flour at 67° F. 1 Specific Heat. 500 „ water at 145° F. J [ = 1000 at 118° P. 0-53 500 flour at 67° F. ^ 500 „ water at 104° F. ; t = 1000 at 93° F. 0-42 500 „ flour at 67° P. 1 500 „ water at 86° F. J [ = 1000 at 80-5° F. 0-40 I heats are calculated from the above experiments in the lollowmg manner : in the first experiment 500 grams of water have fallen from H5 to 118°, that is 27°, during which they must have afforded 500 x ~ 13,500 H.U. At the same time 500 grams of flour have been raised 6 THE TECHNOLOGY OF BREAD-MAKING. from 67° to 118°, that is through 51°, which is equal to 500 x 51 = 25,500 grams through 1°, and to do this 13,500 H.U. have been utilised ; then to raise 1 gram through 1° there has been taken 13.500 25.500 = 0*53 H.U. therefore 0*53 is the specific heat of flour as derived from this experiment. A number of observations have also been [made on the temperatures of mixtures made in the bakehouse on the large scale for manufacturing purposes. The doughs were machine-mixed, and no allowance is made for the salt and compressed yeast, quantities of which were the same in all cases. The quantities, temperatures, and calculated specific heats are given in the following table : — Water. Flour. Dough. Flour. Specific Heat. 0-39 Quarts. 53 Lbs. Temp. 132-5 95° Lbs. 205 Temp. 52-5° Temp. 79-0° 51 127-5 90° 205 50-0° 77-0° 0-30 51 127-5 90° 205 50-0° 77-0° 0-30 53 132-5 98° 205 53-0° 79-0° 0-45 53 132-5 89° 205 53-0° 76-0° 0-36 53 132-5 89° 205 53-0° 76-0° 0-36 The whole of these figures, it must be remembered, are those obtained in experiments made under conditions such as hold in the bakehouse, and represent rather the result of actual working, than theoretic specific heats with all disturbing causes eliminated. In the case of the mixtures made at the higher temperatures, there is naturally a greater loss of heat, and this causes an increase in the corresponding apparent specific heats. In consequence of this, the No. 1 Laboratory Experiment gives a remark- ably high figure ; but the whole of the others lie fairly closely together. Comparing those above given with a large number of observations on the manufacturing scale since made, practically all the specific heat results range between 0‘36 and 0*45, with a mean of 0‘40, to which the majority approach most closely. Taking 0*40 as the working s]3ecific heat of flour, 1 unit by weight of water in falling through 1° raises 2-5 units by weight of flour through the same increment of temperature. 11. Sources of Heat. — ^Directly or indirectly all available terrestrial heat is practically derived from the sun : its immediate source, however, for manufacturing operations is the combustion of different kinds of fuel ; these give out different amounts of heat according to their composition. Tlie following table gives the number of heat units evolved by the com- bustion of one gram of each substance in oxygen : — Heat Developed during Combustion. Substance. Formula Heat Units. Hydrogen H, 34,462 Carbon . . C 8,080 Carbon Monoxide CO 2,634 Marsh Gas CH4 13,063 Olefiant Gas C2H4 11,942 Alcohol . . . . . . C2H5HO 6,909 Welsh Chal about 8,241 Newcastle Coal 8,220 ' D( rbysliire Coal 7,773 Coke 7,000 Wood (dried in air) . . 3,547 INTRODUCTORY. 7 12. Expansion by Heat. — It has already been mentioned that in most cases bodies expand under the influence of heat. Solids expand the least, and at a definite rate for each particular solid ; liquids have a higher rate of expansion, each still having its own special rate ; while gases expand at a far higher rate than either liquids or solids. The following table gives what are termed the Coefficients of Linear Expansions for I° between 0° and 100° 0. Glass.. .. 0*000008613 Brass.. .. 0*000018782 Platinum .. 0*000008842 Lead.. .. 0*000028575 Iron .. .. 0*000012204 Zinc .. .. 0*000029417 Tliese figures mean that each of these substances expands at the rate expressed by its own coefficient : thus 1 foot of glass at 0° C. becomes 1*000008613 foot long at 1° C., and so for each degree rise in temperature. When a body is heated, its whole three dimensions of course increase, and the coefficients of cubical expansion of solids for practical purposes, may be taken as three times their coefficients of linear expansion. The apparent expansion of liquids is not so great as the real, because the vessels in which they are contained also expand. The following table gives the Total Apparent Expansions of Liquids between 0° and 100° C. Mercury . . . . 0*01543 Fixed Oils . . . . 0*08 Distilled Water . . 0*0466 Alcohol . . . . 0*116 The coefficient of apparent expansion for 1° C. is obtained by dividing these numbers by 100, thus that for mercury is 0*0001543. Mercury expands at a practically constant rate from 36° to 100° C. ; water, however, contracts in rising from 0° to 4°, and then expands from 4° to 100° C. 13. Expansion and Contraction of Gases. — There are certain reasons V hich lead us to suppose that at a temperature of — 273° C. bodies would be entirely devoid of heat. This point — 273° C. is therefore often termed the absolute zero of temperature ; and temperature reckoned therefrom is termed “ absolute temperature.” The absolute temperature of a body is its temperature in degrees C. + 273. All gases expand with increase, and contract with diminution, of temperature. The amount of expansion and contraction is the same for all gases between the same limits of tem- perature, provided the temperature is considerably higher than that at which they condense to liquids. The volume of all gases is directly pro- portional to their absolute temperature. Because of this variation with temperature it is necessary to fix a temperature which shall be considered as a standard in expressing the volume of gas : 0° C. is commonly adopted for this purpose. Knowing the volume of a gas at any one temperature, its volume at any other may be easily calculated ; thus, a vessel was found to contain 750 c.c. of air at 15° C. ; it is required to find its volume at the standard tem- perature. 15° C. -f 273 = 288° Absolute Temperature. 0° C. + 273 = 273° As 288 : 273 : : 750 ; 711 c.c. of gas at standard temperature. 14. Relation of Pressure and Volume of Gases. — It is convenient here to note that the volume of a gas is also affected by the pressure to which it is subjected : this variation is governed by what is called Boyle and Marriotte’s Law — ^The volume of any gas is inversely proportional to the 8 THE TECHNOLOGY OF BREAD-MAKING. pressure to which it is subjected. The most important variations of pressure to which gases are liable are those resulting from the changes in pressure of the atmosphere. The height of the mercury column of the barometer is a direct measure of the pressure of the atmosphere, therefore that pres- sure is commonly expressed in the number of millimetres (m.m.) which that column is high. For purposes of comparison it is also necessary to reduce all pressures to one standard ; that selected is an atmospheric pressure which causes the barometer to stand at 760 millimetres. The temperature and pressure quoted as standards for gas measure- ment 0° C. and 760 m.m. are often termed normal temperature and pres- sure ; for this expression the abbreviation, “ N. T. P.” is frequently used. The laws governing the relation between the volume and temperature and pressure of gases must not be regarded as absolutely exact, since they are subject to certain small but well-marked departures. These variations, however, have no direct bearing on the present subject. 15. Transmission of Heat. — ^It is well known that when one part of a body or place is heated, the other parts also become hot more or less quickly. Some explanation of how such transmission is effected must now be given. There are three methods by which heat can be transmitted from one point to another, which are termed respectively Convection, Conduction, and Radiation. 16. Convection. — ^As the word convection implies, a part or mass is heated by the heated matter being conveyed from one part to another. This kind of heating can only occur in liquids or gases where the particles of matter can move freely. One of the best illustrations of convection is the heating of an ordinary vessel of water by the placing of a fire under- neath ; the layer of water at the bottom first gets hot, and consequently expands and becomes of lower specific gravity. As a result of being lighter, it therefore rises to the surface, and its place is taken by other water which is colder and denser. This in its turn is heated and rises ; continuous cur- rents of warm water ascend through the liquid, and colder water descends to take its place. In this way the whole mass is gradually made hot. The heating of the water in a supply cistern on the top of a building by currents through flow and return pipes from a small boiler in the basement is due to convection. So, too, the ventilation of a building is naturally caused in the same way — heated air ascends and makes its way through exits at the highest point, while cold air enters through the joints of doors and windows or apertures specially provided for the purpose. Among other illustrations may be mentioned the warming of a building or room by hot- water pipes running close to the floor. The air is thereby heated and ascends ; the cooler air falls and takes its place. Conversely, a mass of water or air is best cooled by the application of cold at the upper surface. Thus, given a vessel of hot water and a coil of pipes at the surface, through which cold water is passing, the cold water lowers the temperature of the upper layer in the vessel ; this consequently descends and its place is taken by hotter water. In this way a series of currents is set up whereby the whole mass of water is uniformly cooled. It will be seen that convection is a mode of distributing heat through a mass of either liquid or gas by means of moving currents, such currents being usually produced by differences in density due to expansion caused by the source of heat itself. 17. Conduction. — ^Instances are well known in which the application of heat to any one point of a solid causes the whole mass to become hot. Thus, if the end of a bar of iron be placed in the fire, the other end gradu- INTRODUCTORY. 1 ) ally increases in temperature. This cannot be due to convection, but is due to the heating effect which the hot particles of the body have on the contiguous particles. In these cases the heat is said to be transmitted by conduction. Conduction is that method of transmitting heat in which the heat passes from the hotter particles of a body to the colder ones lying in contact with them, and so throughout the whole body. There are wide differences in the power of conducting heat displayed by various substances ; thus, if a bar of copper be heated in the same way as suggested for the iron, the further end becomes hot far more rapidly. If, instead, a rod of glass or porcelain be heated, the outer end gets hot only with extreme slowness. It must therefore be remembered that some sub- stances conduct heat much more rapidly than others. The metals as a class are good conductors, although there are great differences between them. Porcelain, tiles, glass, and earthy substances are generally bad conduc- tors, so also are most bodies of animal or vegetable origin, as, for example, felt, wool, and wood. Water is a bad conductor, and so are the gases. Air is^^one of the worst heat conductors known, consequently porous masses, as slag-wool and fossil earth, conduct very badly, not only from their own non-conducting power, but because of the air retained in their interstices. Owing to their very slight conducting properties, wool, glass, bricks, and similar bodies are frequently termed non-conductors. The following table gives the comparative conducting power of a few substances, silver being taken as 100. Comparative Powers of Conductivity. Silver Copper Iron Lead Marble . . . . . . . . . . . . about Porcelain . . . . . . . . . . . . „ Brick Earth . . . . . . . . . . „ 100 75 10 8 2 1 1 18. Radiation. — It has been already explained that when a substance is hot, its particles are in a state of motion : under circumstances in which transmission of heat by convection and conduction is impossible, one body may yet be heated by another. The explanation now generally accepted is, that all space is permeated by a highly elastic body to which the name of ether has been given, which is capable of being set in undulatory motion by appropriate agitation. The violently moving particles of a hot body in the act of vibration strike against this ether, setting up in it a series of waves. These waves spread in all directions, and on impingeing against a cold body, cause its particles also to assume a state of vibration — ^that is, they make the substance hot. In this way heat passes from one body to the other, not, however, as hot matter, but as a peculiar wave-like motion in the substance called ether. This is known as “ Radiation ” of Heat, and is independent of the temperature of the medium through which radiation occurs. Radiation occurs in straight lines in all directions from the body which is evolving heat, and follows the same general laws of reflection as those which govern light. At the same temperature different bodies radiate heat at different rates. The rate of radiation is affected both by the nature of the radiating material and also the eondition of its surface, whether rough or smooth. Highly polished surfaces radiate less rapidly than those which are roughened. Being maintained at the same temperature, the following table gives the comparative radiating power of different bodies. 10 THE TECHNOLOGY OP BREAD-MAKING. Comparative Power of Radiation. Lampblack (Soot) . . . . . . . , . . 100 White Lead . . . . . . . . . . . . 100 Tarnished Lead . . . . . . . . . . . . 45 Polished Iron . . . . . . . . . . . . 15 Burnished Silver . . . . . . . . . . . . 2*5 When hot, surfaces of clay and brick are good radiators of heat, so also are those of flannel and other like substances. In order that bodies may be heated by radiant heat, it is necessary that they possess the power of absorbing such heat — like radiation, this power of absorption also varies with different bodies. Those which are good radiators of heat are good absorbents, and practically the table showing power of radiation equally applies to power of absorption. A good illustration of the different modes of transmission of heat is furnished by the action of one of the pipes of a steam oven. This pipe contains a certain quantity of water sealed up in the pipe. The pipe is built into the oven on a slight incline so that the lower end is in the fur- nace, and the upper one in the baking chamber of the oven. The fire of the furnace or the heated gases thereby produced are in contact witli the pipe. By conduction the heat finds its way through the iron walls of the pipe and into the water. This is heated by convection currents, and ultimately the steam finds its way into the upper parts of the pipe which are in the oven. The metal is consequently heated by conduction and by conduction the heat passes through to the outer surface. There it partly warms the air by a process of conduction and also sets up radiation by which anything placed in the oven to bake is in due course heated. 19. Mechanical Equivalent of Heat. — It has already been stated that heat is produced when mechanical work is absorbed by friction or per- cussion, as when nail-rod is heated by repeated blows of the hammer. Care- ful measurements have shown that the work done by 1 lb. falling through 772 feet (or 772 ft.-lbs.), is capable of raising the temperature of 1 lb. of water 1° F. : this amount is therefore termed the Mechanical Equivalent of Heat. From this the value in degrees Centigrade is easily calculated, being of 772=1390 ft.-lbs, of work to raise I lb. of water through 1° Centigrade. Introductory Chemical Principles. 20. Definition of Chemistry. — Chemistry has well been defined as that science which treats of the composition of matter, of changes produced therein by certain natural forces, and of the action and reaction of different kinds of matter on each other. It follows that the Chemistry of Wheat, Flour, and Bread may be defined as that branch of the science which treats of the composition of these bodies, of the changes they undergo when subjected to the action of certain natural forces, and of the action and reaction of these and other kinds of matter on each other. 21. Introductory Study Necessary. — An elementary course of study of the general principles of chemistry must precede that of any particular branch of the applied science. Such a course should include the preparation and properties of the commoner elements and their compounds, the prin- ciples of qualitative analysis, and the simpler laws governing chemical action arid combination. For this purpose Jago’s “ Elementary Chem- istry.” and “Advanced Chemistry,” published by Messrs. Longmans & Co., may be employed. For convenience of reference and in response to a widely expressed wish, a short description follows of the most important chemical laws, and also of such elements and compounds as are closely INTRODUCTORY. 11 connected with the chemistry of wheat, flour, and bread. This brief account must not, however, be accepted as a substitute for a systematic course of study of elementary chemistr}^ 22. Indestructibility of Matter. — Chemical changes are often accom- j)anied by very great alterations in the appearance and properties of the bodies involved ; for example, when a candle is burned it almost entirely disappears, but although it no longer remains in the solid state, all its constituents exist as gases, and these weigh exactly the same as did the candle, flus the oxygen of the air with which they have combined. Matter is indestructible, and, consequently, the same weight of material remains after any and every chemical change as there was before its commencement. 23. Preliminary Definitions. — It is important that at the outset accurate and concise ideas are gained of the meaning of various chemical terms. Although matter assumes so many diversified forms, yet all bodies, on being subjected to chemical analysis, are found to consist of one or more of a class of about eighty substances, which are termed “ elements.” An Element is a substance which has never been separated into two or more dissimilar substances. Recent chemical researches go to show that some of the bodies now regarded as elements, may after all be composed of more than one substance. However interesting such investigations may be, they are not likely to have any bearing whatever on our present subject. While the letters of the alphabet are few, the number of words which can be formed from them is practically infinite ; so, in a somewhat similar fashion, from the comparatively small number of elements which constitute the “ alphabet ” of chemistry, there may be built up an immense number of chemical compounds. A compound is a body produced by the union of two or more elements in definite proportions, and, consequently, is a substance which can be separated into two or more dissimilar bodies. Compounds differ in appearance and characteristics from their constituent elements. The term “ Mixture ” is applied to a substance produced by the mere blending of two or more bodies, elements or compounds, in any proportion, without union. Each component of a mixture still retains its own properties, and separation may be effected by mechanical means. 24. List of Elements. — The following is a list of some of the more impor- tant elements, together with their symbols and other particulars : — Name. Symbol. Combining or Atomic Weight. Atomicity or Quantivalence, Aluminium . . . . A1 Old. 27 New. 26-9 IV Barium Ba 137 1364 II Boeon . . B II 10-9 III Beomine . . Br 80 79-36 I Calcium . . Ca 40 39-8 II Caebon . . C 12 11-91 IV Chloeine . . . . Cl 35*5 35-18 I Chromium . . . . Cr 52 51-7 VI Copper (Cuprum) . . . . Cu 63 63-1 II Fluoeine . . .. F 19 18-9 I Hydeogen . . .. H I 1-0 I Iodine .. I 126 125-9 I Iron (Ferrum) . . Fe 56 55*6 VI Lead (Plumbum) . . . . Pb 205 205-35 IV Magnesium . . .. Mg 24 24-18 II 12 THE TECHNOLOGY OF BREAD-MAKING. Name. Symbol. Combining or Atomicity or Atomic Weight. Old. New. Quantivalence. Manganese . . . . Mn 55 54-6 VI Mercury (Hydrargyrum) .. Hg 199 198-5 II Nitrogen . . .. N 14 13-93 V Oxygen .. 0 16 15-88 II Phosphorus . . P 31 30-77 V Platinum .. Pt 193 193-3 IV Potassium . . .. K 39 38-86 I Silicon .. Si 28 28-2 IV Silver (Argentum) . . .. Ag 107 107-12 I Sodium (Natrium) . . .. Na 23 22-88 I Sulphur .. S 32 31-83 VI Tin (Stannum) . . Sn 118 118-1 IV Zinc . . . . Zn 65 64-9 II 25. Recently Discovered Elements. — Considerable interest attaches to certain elements which have recently been discovered. Among these are argon and other allied elements which exist in the atmosphere, and radium, a constituent of pitch-blende. As none of these bodies has appa- rently a bearing on the chemistry of bread -making they are not dealt with in this work. 26. Metals and Metalloids. — ^The elements are divided into two groups, termed respectively “ Metals,” and “ Metalloids ” or non-metals. The non-metals are distinguished in the foregoing table by being printed in small capitals. The line of division between the two classes is not very marked, the one group gradually merging into the other. The metals, as a class, are opaque bodies, having a peculiar lustre known as metallic ; they are usually good conductors of heat and electricity. Two of the elements, mercury and bromine, are liquid at ordinary temperatures, while hydrogen, oxygen, nitrogen, and chlorine are gaseous. 27. Symbols and Formulae. — ^The symbols are abbreviations of the names of the elements, and, where practicable, consist of the first letter of the'Latin names. When two or more elements have names commencing with the same letter, it becomes necessary to distinguish them from each other by restricting the initial letter to the most important element, and selecting two letters as the symbol of each of the others. Thus, carbon and chlorine each commence with “ C,” that letter is chosen as the symbol of carbon, while that of chlorine is Cl. As all compound bodies consist of elements united together, they may be conveniently expressed symbolically by placing side by side the symbols of the constituent elements ; the symbol of a compound is termed its for- mula. Thus, common salt consists of chlorine and sodium ; its formula is accordingly written, NaCl. 28. Further Uses of Symbols and Formulae : law of chemical com- bination by weight. — Simply as abbreviations of the full names, symbols and formulae are of great service ; this, however, is but a small part of their significance and value to the chemist. Their further use may best be explained by reference to certain information gained by experiment, to which careful attention is requested. On analysis, it is found that 36’5 ounces of the substance known as hydrochloric acid consist of 1 ounce of hydrogen, combined with 35'5 ounces of chlorine ; also, that in 58'5 ounces of common salt there are 35*5 ounces of chlorine to 23 of sodium. Taking water as another instance of a hydrogen compound, analysis show^s that its composition may be expressed by the statement, that 18 ounces INTRODUCTORY. la of water consist of 2 ounces of hydrogen combined with 16 ounces of oxygen. In the table given on page II there is a column headed “Combining or Atomic Weight ; ” on referring to this it will be found that the numbers opposite hydrogen, chlorine, sodium, and oxygen, are, respectively, 1,35*5, 23, and 16, being (with one exception) identical with those that have just been given as the numbers obtained by analysis of the compounds under consideration. It is possible to assign to every element a number, which number, or its multiple, shall represent the proportionate quantity by weight of that element which enters into any chemical compound. These numbers are termed the “ Combining or Atomic Weights ” of the elements, and are deduced from results obtained on actual analysis. In addition to its use as an abbreviated title of any element, the symbol represents the quantity of the element indicated by its combining weight ; where multiples of that quantity exist in a compound, the fact is expressed by placing a small figure after the symbol and slightly below the line. In the table of elements there are two columns of combining weights given, headed respectively “ Old ” and “ New ” ; the second column gives those obtained as a result of the most recent research and which represent the most exact determinations as yet made. For most purposes, the weights given in the first column are sufficiently accurate. As previously stated, the formula of sodium chloride is NaCl, and it contains 23 of sodium to 35 5 of chlorine. The formula of hydrochloric acid is HCl, and it contains 1 of hydrogen to 35*5 parts of chlorine. Water consists of 2 parts of hydrogen to 16 of oxygen ; the fact that it contains twice the combining weight of hydrogen is expressed by writing the formula, H 2 O. Again, ammonia contains 3 parts by weight of hydrogen to 14 parts of nitrogen, consequently it has the formula, NHg : the substance commonly termed carbonic acid gas consists of 32 parts, or twice the com- bining weight, of oxygen to 12 by weight of carbon, the formula is con- sequently COg. The quantity of an element represented by its combining weight is termed “ one combining proportion ” of that element. 29. Constitutional Formulae. — In addition to simply showing the number of atoms of each element present, formulae are frequently so written as to show the probable constitution of the resultant compounds ; such formulae are termed “ Constitutional Formulae.” 30. Chemical Equations. — Chemical changes are most conveniently expressed by what are termed “ chemical equations ” : these consist of the S 3 mibols and formulae of the bodies participating, placed before the sign =, while those of the resultant bodies follow. As an instance it may be mentioned that, when a solution of potassium iodide is added to one of mercury chloride, potassium chloride and mercury iodide are produced. The equation representing this chemical action is written thus : — 2KI -f HgCla = 2KC1 -f Hgl2. Potassium Iodide. Mercury Chloride. Potassium Chloride. Mercury Iodide. Having access to a table of combining weights, the chemist learns from this equation that two parts of potassium iodide, each containing one combining proportion of potassium weighing 39, and one of iodine w^eighing 126 together with one part of mercury chloride, containing one combining proportion of mercury weighing 199, and two of chlorine each weighing 35*5, together yield or produce two parts of potassium chloride, each consisting of one combining proportion of potassium w^eighing 39, and one of chlorine w^eighing 35*5, and one part of mercury iodide, containing one combining proportion of mercury w^eighing 199, and tw^o combining proportions of iodine each weighing 126. As no chemical change affects 14 THE TECHNOLOGY OF BREAD-MAKING. the weight of matter, the weight of the quantity of a compound, represented by its formula, must be the sum of that of the constituent elements : so, too, the weight of the bodies resulting from a chemical change must be the same as that of the bodies before the change, whatever it may be, had occurred. Although from a chemical equation and table of combining weights, it is possible to state what relative weight of each element is con- cerned in any chemical action, it must never be ^forgotten that the com- bining weights were first determined by experiment and then the table com- piled therefrom. The statement of premise and deduction is, that hydrogen and chlorine have respectively the combining weights of 1 and 35*5 assigned to them, because analysis shows that they combine in those proportions ; not that hydrogen and chlorine have as combining weights 1 and 35*5, and therefore they must combine in those proportions. The combining weights are simply a tabular expression of results obtained by practical analytic investigation. 31. Atoms and Molecules. — The fact that the quantity of every element which enters into combination is either a certain definite and unchangeable weight, or a multiple of that weight, led chemists to regard this weight of a combining proportion of an element as being in some way associated with its physical nature. The first step toward the explanation of this question is due to Dalton, who enunciated what is termed the Atomic Theory. He assumed that all matter is built up of extremely small particles, which are indivisible, and that when elements combine, it is between " these particles that the act of union occurs. These ultimate particles of matter are termed “Atoms.” The name “atom” is derived from the Greek, and signifies that which is indivisible. Atoms of the same element are supposed to be of the same size and weight. With the absolute weight of atoms the student of bread-making chemistry has but little to do : the prin- cipal point of importance for him is their relative weights compared with each other. For chemical purposes, an atom may be defined as the smallest particle of an element which enters into, or is expelled from, a chemical compound. For the phrase, “ combining proportion,” hitherto used, the term “ Atom ” may be substituted ; the combining weight then becomes the relative weight of the atom of each element compared with that of hydrogen, which, being the lightest, is taken as unity. Though the atomic theory does not admit of absolute proof, yet it so amply and consistently explains all the phenomena of chemistry that its essential principles are universally recognised. The little group of atoms represented by the formula of a compound is termed a “ molecule.” A molecule is the smallest possible particle of a substance which can exist alone. In the case of chemical compounds the molecule cannot be further subdivided, except by separation into the atoms of its constituent elements, or into two or more molecules of some simpler chemical compound or compounds. When elements are in the free or uncombined state, their atoms usually combine together to form elementary molecules : thus with oxygen, two atoms unite to form a mole- cule of oxygen ; the formula of the oxygen molecule is written, O2. Tlie molecules of the following elements contain two atoms : — hydro- gen, chlorine, oxygen and nitrogen. As all elements normally exist in the molecular state, it is frequently advisable to use equations in which the lowest quantity of any element ])resent is a molecule. Thus, H2 + CI2 — 2 HC 1 , should be written as the e({uation representing the combination of hydrogen and chlorine, rather tlian H -h Cl = HC'l. This rule applies more especially to the gaseous elements, as their molecular constitution lias been definitely ascertained. But ill the case of tlie solid elements the number of atoms in the molecule INTRODUCTORY. 15 is not so well-known and therefore such elements are usually written as so many single atoms, and not as molecules. 32. Avogadro’s Law. — The fact that all gases, whether elementary or compound, expand and contract at the same rate, when subjected to variations of temperature and pressure, has an important bearing on their probable molecular constitution. Their similarity in this respect has led to the assumption express£d in the “ Law of Avogadro ” : — “ Under similar conditions of temperature and pressure, equal volumes of all gases contain the same number of molecules.” From this it follows, that at the same temperature and under the same pressure, the volume of any gaseous molecule is the same whatever may be the nature and composition of the gas. The density of a gas being known, its molecular weight is easily calculated. The clensity of a gas is the weight of any volume, com- pared with that of the same volume of hydrogen, measured at the same temperature and pressure, and taken as unity. It has already been stated that the molecule of hydrogen contains two atoms ; its molecular weight, expressed in terms of its atomic weight, is consequently 2. The molecular weight of any gas is the weight of that volume which occupies the same space as do two parts by weight of hydrogen ; or is identical with the number obtained by doubling the density. Similar conditions of temperature and pressure are always understood in speaking of the comparative weights of gases. Conversely, as the molecular weight is the sum of the weights of the constituent atoms, the density of a gas may be calculated from its formula. Thus, carbon dioxide gas has as its formula, CO, ; its molecular 44 weight is 12 + (16 x 2=) 32 = 44; the density is ^ =22. Here again it must be remembered that the molecular weight is primarily determined from the density, and not the density from the molecular weight. 33. Absolute Weight of Hydrogen. — ^As hydrogen is taken as the unit of comparison for other gases, it is necessary that its absolute weight be determined with the greatest exactitude. Experiment has shown that 1 litre of hydrogen, at normal temperature and pressure, weighs 0*0896 gram ; or 11*2 litres weigh 1 gram. The student must make up his mind to remember this figure ; to quote Hofmann, the fact that at 0° C. and 760 m.m. pressure, 1 litre of hydrogen weighs 0*0896 gram, should be impressed “as it were with a graving tool on the memory.” The weight in grams of a litre of any gas is its density X 0*0896. Thus, the density of carbon dioxide gas is 22; the weight of a litre is 22 x 0*0896 = 1*9712 grams. 34. Laws of Chemical Combination by Volume. — Not only does chemical combination follow definite laws, so far as weight is concerned, but also equally definite laws govern the proportions by volume in the case of gaseous bodies. For example, experiment shows that one volume of hydrogen unites with one volume of chlorine to form two volumes of hydrochloric acid gas. So, too, two volumes of hydrogen unite with one volume of oxygen to form two volumes of water-gas (steam). Again, ammonia consists of three volumes of hydrogen, united with one of nitrogen, to form two volumes of ammonia. The reactions are expressed in the following equa- tions :• — H^ + CI 2 — 2HC1. Hj^lrogen. Chlorine. Hydrochloric Acid. 2 H 2 + O 2 — 2 H 2 O. Hydrogen. Oxygen. Water. 3 H 2 + N 2 2NH3. Hydrogen. Nitrogen. Ammonia. It will be observed that in the first equation one molecule of hydrogen 16 THE TECHNOLOGY OF BREAD-MAKING. unites with one molecule of chlorine to form two molecules of hydrochloric acid : the application of Avogadro’s Law, therefore, teaches that these elements will unite in equal quantities of one volume to form two volumes, of hydrochloric acid. In the same way, the proportions by volume in which chemical changes occur between gaseous bodies are always expressed in the equation, it being remembered that all gaseous molecules occupy the same space when measured at the same temperature and pressure. The following is a useful method of writing such equations, when the object is to show the proportions by volume in a chemical change in which any gaseous body is involved. H 2 + CI 2 2HC1. 1 volume. 1 volume. 2 volumes. 2H2 + O2 — 2H2O. 2 volumes. 1 volume. 2 volumes. 3H2 + N2 2NH3. 3 volumes. 1 volume. 2 volumes. 35. Acids, Bases, and Salts. — ^The name acid is a famihar one, because it is continually applied in everyday parlance to anything which is sour. A number of bodies possess this distinction in common ; to the chemist,, the sourness of an acid is but an accidental property, as, according to his definition of these bodies, substances are included as acids that are not sour to the taste. An acid may be defined as a body which contains hydrogen, which hydrogen may be replaced by a metal (or group of elements equivalent to a metal), when presented to the acid in the form of an oxide or hydroxide (hydrate). As a class, the acids are sour ; they are also active chemical agents ; most acids are characterised by the property of changing the colour of a solution of litmus, a naturally blue body, to a red tint. Oxygen is a constituent of most acids. These are termed “ oxy-acids.” A few in which it is absent are termed “ hydr-acids.” Hydrochloric acid, HCl, is an example of these bodies. Most of the oxy-acids are produced by the union of water with an oxide — thus, oxide of sulphur and water form sulphuric acid : — SO3 + H2O == H2SO4. Sulphur Trioxide. Water. Sulphuric Acid. The oxides, which by union with water form acids, are termed anhydrides, or anhydrous acids. They are usually non-metallic oxides, but sometimes consist of metals combined with a comparatively large number of atoms of oxygen. A Base is a compound, usually an oxide or hydroxide, of a metal (or group of elements equivalent to a metal), which metal (or group of elements) is capable of replacing the hydrogen of an acid, when the two are placed, in contact. The greater number of metallic oxides are bases. Bases, as well as acids, differ considerably in their chemical activity. Certain l)ases are characterised by being soluble in water, to which they impart a peculiar soapy feel. These bases are termed “ alkalies,” and possess the property of restoring the blue colour to reddened litmus. The most important alkalies are sodium hydroxide, NaHO, and potassium hydroxide, KHO. The bases, lime, CaO, baryta, BaO, and magnesia, MgO, are more or less soluble in water, and also turn reddened litmus blue. They, with SrO, constitute the group known as the “ Alkaline Earths.” Hydroxides are compounds of oxides with water, thus : — Na20 + H 2 O 2NaHO. ‘ Sodium Oxido. Water. Solium Hydroxide. When an acid and base react on each other, the body, produced by the replacement of the hydrogen of the acid by the metal of the base, is termed a Salt. Water is also produced during the reaction. When the acid and INTRODUCTORY. 17 base which have thus reacted are both of something like the same degree of strength, the resultant salt is commonly without action on litmus ; that is it does not affect the colour whether it be red or blue. The salt is then said to be neutral. For example, when sulphuric acid, a strong acid, acts on potassium hydroxide, a strong base, the resultant salt, potassium sulphate, has no action on litmus. But when the acid is strong and the base feeble, or vice versa, the resultant salt will be governed in its degree of neutrality by the predominant component. Thus when potassium hydroxide com- bines with carbonic acid (a weak acid) the salt, potassium carbonate, is strongly alkaline to litmus. That is, it vigorously restores the blue colour to litmus which has been reddened. The action of acid and base on each other is illustrated in the following equation : — HCl -f NaHO = NaCl -f H^O. Acid. Base. Salt. Water. 36. Compound Radicals. — ^At times a group of elements enters into the composition of a body, and performs functions very similar to those of an atom of an element. Such groups are not only found to form numbers of very definite compounds, but may be even transferred from one com- pound to another without undergoing decomposition. Groups of atoms of different elements which possess a distinct individuality throughout a series of compounds, and behave therein as though they were elementary bodies, are termed “ Compound Radicals.” 37. Quanti valence or Atomicity. — Referring back to the three com- pounds of hydrogen mentioned in paragraph 34, it will be observed that one atom each of chlorine, oxygen, and nitrogen, combines respectively with one, two, and three atoms of hydrogen. If chlorine and oxygen com- pounds be classified and compared, it is found that oxygen in almost every instance combines with just double as many atoms of the other element as does chlorine. The atom-combining power of elements varies — Quan- tivalence or Atomicity is the measure of that combining power. Among the elements, hydrogen, sodium, and chlorine are characterised by the fact that one atom of each rarely combines with more than one atom of any other element. Their atomicity is unity, and as every other element forms a chemical compound with one or more of these, the atomicity of any element can usually be determined by observing with how many atoms of one of these three elements an atom of the element in question enters into combination. The atomicity of the different elements is given in the table included in paragraph 24. Elements with an atomicity of one are termed monads ; of two, dyads ; three, triads ; four, tetrads ; five, pentads ; and of six, hexads. It is often convenient to express the atomicity of an element graphically. This is done by attaching a series of lines to the atom, according to its atomicity. These lines may be viewed as indicat- ing the number of links or bonds with which the particular atom can combine with other atoms. Of the actual nature of the force which holds atoms together in chemical compounds, nothing can be here stated : the bonds must only be viewed as indications of the number of such units of atom- combining power. The following are examples of these graphic symbols : — - H— Cl— — 0— — =zC = Hydrogen. Chlorine. Oxygen. Boron. Carbon. The same two elements often form a series of two or more compounds with each other ; under these circumstances the atomicity must vary. In the great majority of such compounds, the atomicity increases or diminishes by intervals of two — that is, the atomicity is either even or odd for an element throughout all its compounds. This is sometimes c 18 THE TECHNOLOGY OF BREAD-MAKING. accounted for by the supposition that two of the bonds of an element may, by their union, mutually satisfy each other. This is not, however, invari- ably the case, as certain well-marked exceptions to this rule are known. The highest knov/n atomicity of an element is termed its “ absolute ” atomicity ; the atomicity in any particular compound is the “ active ” atomicity ; the absolute, less the active, atomicity is the “ latent ” atom- icity. 38. Basicity of Acids. — In order to form salts, different acids require different quantities of a base : the measure of this quantity is termed the “ basicity ” of the acid. The basicity of an acid depends on the number of atoms of hydrogen it contains that may be replaced by the metal of a base. In forming salts, one atom of hydrogen is replaced by one atom of a monad metal, two atoms of hydrogen by an atom of a dyad, and so on. In the case of acids which contain more than one atom of replaceable hydrogen, salts are sometimes formed in which a part only of the hydrogen is replaced ; such salts are termed “ acid ” salts, while those in which the whole of the hydrogen is replaced are termed “ normal ” salts. The follow- ing are typical examples of acids and the corresponding salts : — Monobasic Acid. HNO3. Nitric Acid. NaNOe. Sodium Nitrate. Ca(N03)2. Calcium Nitrate. Dibasic Acid. H2SO4. Sulphuric Acid. Na2S04. Sodium Sulphate. HNaSO,. Acid Sodium Sulphate. CaS04. Calcium Sulphate. Tribasic Acid. H3PO4. Phosphoric Acid. Na3P04. Sodium Phosphate. Na2HP04. Disodic Hydrogen Phosphate. Ca3(P04)2* Calcium Phosphate. It is often convenient to view the acids in the light of their being com- pounds of the anhydrides with water : the corresponding salts may then be written as compounds of the bases with the anhydrides. This method is almost invariably employed when calculating the relative quantities of metals and acids in bodies when subjected to analysis. Subjoined are the formulse, written in this manner, of the acids and salts previously given as examples : — H3O, N2O5. Two Molecules of Nitric Acid. Na20, N2O5. Two Molecules of Sodium Nitrate. CaO, N2O5. One Molecule of Calcium Nitrate. H2O, SO3. Sulphuric Acid. Na20, SO3. Sodium Sulphate. Na20, H2O, (803)2. Two Molecules of Acid Sodium Sulphate. CaO, SO3. Calcium Sulphate. (H20)3, P2O5. Two Molecules of Phosphoric Acid. (Na20)3, P2O5. Two Molecules of Sodium Phosphate. (NaaOjH^O, P2O5. Two Molecules of Disodic Hydrogen Phosphate. (CaO) 3 , P2O6. One Molecule of Calcium Phosphate. 39. Chemical Calculations. — ^Most of the chemical calculations necessary in analytic work may be readily made by the help of chemical formulse and equations, together with a table of combining weights. The following are illustrations of some of the most important of these calculations. 40.* Percentage Composition from Formula. — Chemists usually express the results of analysis of a substance in parts per cent., so that in the case of a chemical compound it is often necessary to be able to calculate its chemical formula from the percentage composition ; or conversely, the percentage composition from the formula. The latter operation, as being INTRODUCTORY. 19 the simpler, shall be first explained. It is possible from the formula of any body to arrive at the molecular weight of the compound, and the relative weight present of each element. Thus, to find the percentage composition of acid sodium sulphate : — The formula is Na H S O4 23 + 1 + 32 + (16 X 4 =--) 64 = 120. From the combining weights, given beneath each element, with their sum at the end, it is seen that the molecule weighs 120, and contains 23 parts of sodium. Knowing that 120 parts contain 23, it is exceedingly easy to calculate the number of parts per 100, as the problem resolves itself into one of simple proportion : — As 120 : : 100 : : 23 : : 19-17 per cent, of sodium. As 120 : : 100 : : 1 : 0-83 ,, hydrogen. As 120 ; : 100 : : 32 ; : 26-66 , , sulphur. As 120 : : 100 : : 64 : 53-33 „ oxygen. 99-99 Precisely the same method of calculation has been applied to the deter- mination of the percentages of hydrogen, sulphur, and oxygen. As the results seldom work out to a terminated decimal, the added percentages usually amount to only 99-99 ; but by continuing the calculation, any additional number of 9’s could be obtained, and as 0-9 recurring is equal to 1-0, so 99-9 recurring is equivalent to 100-00. As another example, let it be required to determine the percentage of base and anhydrous acid respectively in calcium phosphate. This salt is represented by — (Ca 0 )3 P2 O5 (40+16=)56x 3 62-h80 168 ^ -f 14^^ = 310 The molecule, which weighs 310, contains 168 of lime (CaO) and 142 of phosphoric anhydride (P2O5); consequently As 310 : 100 : : 168 : 54-19 per cent, of lime. As 310 : 100 : : 142 : 45-81 ,, ,, phosphoric anhydride. 100-00 41. Formula from Percentage Composition. — Let the following represent the results of analysis of a body Sodium Nitrogen . . Hydrogen . . Phosphorus Oxygen . . 16-79 . . 10-22 3-65 . . 22-63 . . 46-71 100-00 As a first step toward obtaining the formula, divide the percentage of each element by its atomic weight, the result will be a series of numbers in the ratio of the number of atoms of each element — 20 THE TECHNOLOGY OF BREAD-MAKING. 16*79 23 1^*22 14 3*65 1 22^3 46*71 16 0*73 of Sodium. 0*73 of Nitrogen. 3*65 of Hydrogen. 0*73 of Phosphorus. 2*92 of Oxygen. It is next necessary to find the lowest series of whole numbers that corre- spond to these ; such a series may be obtained by dividing each number by the lowest one of the series : — 0*73 0-73 Oy^73 0*73 3*65 0*73 0*73 0*73 2^92 0*73 = 1 atom of Sodium. = 1 atom of Nitrogen. = 5 atoms of Hydrogen. = 1 atom of Phosphorus. = 4 atoms of Oxygen. The formula of the compound is, therefore, Na]NH 5 p 04 ; itsname is “hy- drogen ammonium sodium phosphate."' The formula obtained in this way is the simplest possible for the body in question : it is evident that the per- centage composition would be the same if there were double or any other multiple of the number of atoms of each element in the molecule. Other considerations are taken into account in determining whether the correct molecular formula is really the simplest thus obtained, by calculation, from the percentage composition, or a multiple of the same. Such simplest possible formula is termed an Empirical Formula. 42. Calculations of Quantities. — An exceedingly common type of calcula- tion is that in which it is required to know the quantities of one or more substances required to produce a certain quantity of another body. Thus, hydrogen is commonly obtained by the action of zinc on sulphuric acid ; suppose that 10 grams of hydrogen are required for some operation : what weights respectively of zinc and sulphuric acid are necessary for the pur- pose ? Here, again, the equation gives the relative weights of each ele- ment and compound participating in the reaction. In every such calcula- tion it is absolutely necessary that the equation and combining weights be known ; but granted these, no other difficulties arise beyond those which can be readily overcome by an intelligent application of the principles of proportion. In the case in question the equation is : — Zn + H 2 S O 4 = Zn S O 4 + H 2 . 65 2 + 32 + 64 65+32 + 64 2 . 98 ^ 161 Zinc Sulphuiic Acid. Zinc Sulphate. Hydrogen. To produce two parts by weight of hydrogen, 65 of zinc and 98 of sul- phuric acid are required, then — INTRODUCTORY. 21 As 2 : 10 : : 65 : 325 grams of zinc required. As 2 : 10 : : 98 : 490 ,, ,, sulphuric acid required. Another instance may be given, in which not only weights but also volumes of gases have to be calculated. It is required to know how much carbon dioxide gas in cubic centimetres and in cubic inches is evolved by the fermentation of 28*35 grams (= 1 ounce) of [pure cane sugar, the gas being measured at a temperature of 20° C. and 765 millimetres pressure ; it being assumed that the whole of the sugar is resolved into alcohol and carbon dioxide. The chemical changes involved in this process may be represented by the following equations : — 144+22 + 176 U2 Cane Sugar. + H, 0 2 + 16 "Is" Water. 2C, H,, 0,. 72 + 12+96 2x180=360 Glucose. In the first place one molecule, equalling 342 parts by weight of cane sugar, is converted into two molecules of glucose, each weighing 180, or the two weighing 360. 2C, H„ O, 72+12+96 2x180=360 Glucose. 4C2H5H 0 21+5+1 + 16 ^ 46^184 Alcohol. + 4C O 2 . 12+32 4>S=176 Carbon dioxide. The two molecules of glucose, weighing 360, are next decomposed into four molecules of alcohol, having a total weight of 184 ; and four molecules of carbon dioxide, each weighing 44, and the whole 176. From 342 parts by weight of cane sugar, 176 parts by weight of carbon dioxide are produced ; then — As 342 : 28*35 : : 176 : 14*59 grams of carbon dioxide, yielded by 28*35 grams of cane sugar. The next step is to determine what is the volume of 14*59 grams of car- bon dioxide at N.T.P. The molecular weight of carbon dioxide being 44, its density must be 22 ; one litre of hydrogen weighs 0*0896 grams, and therefore 1 litre of carbon dioxide must weigh 0*0896 X 22 = 1 *9712 grams ; then — i WlZ "" N.T.P. Applying the laws previously given by which the relations between the volume and temperature and pressure of a gas are governed ; then — As 273 : 293 : : 7401 ) _ 293 X 760x7*401 765 : 760 • J 273 x 765 = 7*891 litres at 20° C. and 765 m.m. pressure = 7891 cubic centimetres As 16*39 c.c. = 1 cubic inch, then = 481*7 cubic inches. 16*39 28*35 grams or one ounce of cane sugar would yield, according to the ques- tion given, 7891 c.c. or 481*7 cubic inches of carbon dioxide gas at 20° C. and 765 m.m. pressure. The weight of sugar necessary to yield a certain volume of gas would be calculated on the same principles ; as an illustration, the reverse of the ^calculation just made is appended. Required to know the weight of cane 22 THE TECHNOLOGY OF BREAD-MAKING. sugar necessary to produce 481*7 cubic inches or 7891 cubic centimetres of carbon dioxide gas at 20° C. and 765 mm. pressure. 273x765x7891 293x760 =7401 c.c. at N.T.P. = 7*401 litres. 7*401X1*9712=14*59 grams of CO 2 . As 176 : 14*59 : : 342 : 28*35 grams of cane sugar required. 43. Gaseous Diffusion. — It is a well-known fact that gases mix with each other with remarkable readiness. For instance, if in a large room a jar of chlorine is opened at the level of the floor, the presence of the gas may be detected by its powerful odour, within a few seconds, in every part of the room. The natural process by which the chlorine is thus disseminated through the air is termed “ gaseous diffusion ; it takes place between gases, even though the heavier is at first at the lower level. In other words,, a heavy gas will diffuse up into a superincumbent light gas, while the light gas will make its w'ay downwards and mix with the heavier one. In this way different gases, when placed in the same space, rapidly produce of themselves an uniform mixture. Tliis process of diffusion will also go on through a porous membrane, as, for example, a thin diaphragm of plaster of Paris or porous earthenware. Thus, if a vessel be divided into two parts by a thin partition of porous material, and the one half be filled with one gas and the other with another, they will be found after some time to have become thoroughly intermixed with each other. The rate of diffusion of all gases through such a diaphragm is not the same, but depends on their den- sities. The rate of diffusion of gases is inversely as the square root of their density. Thus, hydrogen and oxygen have respectively densities of 1 and 16 ; hydro- gen diffuses four times as rapidly as does oxygen. 44. Solution. — ^When certain solid substances, of which salt is a con- venient example, are added to water, the solid disappears, and is said to be dissolved. The liquid which has been used for dissolving the substance is said to be a solvent, the substance which is dissolved is called a solute, and the liquid which as a result contains the dissolved substance is termed a solution. Solutions may be prepared of gases, liquids and solids, liquid solution may be defined as a homogeneous or uniform liquid mixture of a gas, a liquid, or a solid with a liquid. The act of solution is not in itself one of chemical combination between the dissolved substance and the solvent (although solution may be followed in addition by chemical com- bination). Thus when a solution of salt in water is heated, the water may be driven off and the whole of the salt recovered in an unchanged condition. 45. Gaseous Solution. — Gases vary very greatly in their degree of solu- bility in water. In the following table is given the volumes of each gas dissolved in 100 volumes of water, at the temperatures of 0° and 15° C. respectively — Hydrogen O’C. 2*15 15°C. 1*91 Nitrogen 2*03 1*48 Oxygen 4*11 2*99 Chlorine solid 23*68 Carbon dioxide 179*67 100*20 Sulphur dioxide 6886*1 4356*4 Hydrochloric acid . . . . 50590*0 45800*0 Ammonia . . 104960*0 72720*0 •mparatively small quantities of hydrogen, nitrogen. and oxygen INTRODUCTORY. 23 thus dissolved, but that of oxygen is sufficiently large to have most important results in the economy of nature. Carbon dioxide is much more soluble, water absorbing about its own volume at ordinary temperatures. The last mentioned gases are examples of extremely soluble gases ; their various solutions have important applications in chemistry and the arts. It will be observed that all the gases mentioned are less soluble in water at 15*^ than at 0° C., and as the temperature is raised the solubility still further diminishes. Most gases may, in fact, be entirely expelled from water by the act of boiling. The weight of a gas dissolved by water is increased by pressure, and is governed by an interesting law, viz., that it is directly pro- portional to the pressure exerted. As the volume of a gas is in inverse ratio to the pressure, it follows that the volume of a gas dissolved by water is the same at all pressures. The so-called mineral or aerated waters are prepared by forcing carbon dioxide into the water under pressure. On the release of the pressure the gas escapes and causes the familiar effervescence. Most of the gases mentioned in the foregoing table are much more soluble in alcohol than in water ; thus 100 volumes of alcohol at 15° C. dissolve 28 volumes, of oxygen and 320 volumes of carbon dioxide respectively. 46. Solution of Liquids. — ^Some liquids on being placed together mix or are said to be “ miscible in all proportions ; an example of these is found in alcohol and water. Others practically refuse altogether to mix, as, for example, water and oil. Others again are to a limited extent soluble in each other. One of the best illustrations of these is that of water and ether ; if these be shaken together in about equal proportions and then allowed to stand, the ether being the lighter, separates out as a layer on the surface of the water. On examination, however, the ether will be found to have water dissolved in it to the extent of about 3 per cent. ; and the water will have dissolved about 10 per cent, of ether. (As a matter of fact, oils and water are also very slightly soluble in each other, but the amount of oil so dissolved is so minute as to be a negligible quantity, while traces only of water are dissolved by oil.) 47. Solution of Solids. — ^Solids vary very greatly in their degree of solubility in water. Among the mineral salts, barium sulphate is almost absolutely insoluble ; calcium sulphate is dissolved to the extent of 1 part in 700 parts of water ; while at the other end of the scale 2 parts of crystal- lized magnesium sulphate are dissolved by 3 parts of water at ordinary temperatures. In the majority of instances the solubility of substances in water is increased by an elevation of temperature, but this is not an at solute rule. Lime, for example, is much more soluble in cold than in hot water. Salt is almost equally soluble in cold and hot water ; at 0° C. water dissolves 35*5 per cent, of salt, and 41 ’2 per cent, at 109*5° C., the boiling point of the solution. Sugar, on the other hand, is soluble in about half its weight of cold water, and in boiling water in all proportions. In order to deter- mine the solubility of any particular substance, it must be allowed to remain in contact with the solvent until the latter has dissolved as much as it possibly can, and leaves the excess in contact with the solution. Under such conditions, the solvent takes up a definite proportion of the dissolved body for each particular temperature. A perfect solution is quite clear and free from any eloudiness, as the solid partieles will have completely disappeared from sight. Any turbidity is caused by the presence of minute solid or liquid particles in susrension. It is incorrect, therefore, to speak of a mixture of a permanently solid sub- stance with water in the form of a creamy mass as a solution. Similarly one does not dissolve yeast in water ; one is simply broken down into an intimate admixture with the other. Water dissolves many of the mineral 24 THE TECHNOLOGY OF BREAD-MAKING. salts, but does not dissolve resins or fatty matters. The resinous bodies, of which shellac may be taken as an example, are soluble in alcohol ; while fats may be readily dissolved by ether, chloroform, and light petroleum spirit. Water, on the other hand, dissolves certain gelatinous and gummy bodies, but such solutions have special characteristics to which further reference is made in the following paragraphs. 48. Osmose and Dialysis. — Liquids which are miscible with each other in somewhat the same way as gases, also undergo diffusion more or less rapidly. The laws governing diffusion of liquids are more complex than those affecting the diffusion of gases : not only gases, but also liquids, are capable of diffusion through a porous diaphragm ; such diffusion is termed “ Os- mose.” Some of the most remarkable and important phenomena of liquid diffusion are those exhibited by aqueous solutions of different substances. Thus, let a sort of drum-head be made by stretching and fastening a piece of bullock’s bladder, or either animal parchment or vegetable parchment paper, over a cylinder of some impervious material, as glass or gutta percha. Float this in a vessel of pure water, and pour inside it a strong solution of common salt. The brine and the pure water will only be separated from each other by the thin membrane of bladder or other similar material. After the lapse of some hours it will be found that the solution of salt will have diffused out through the membrane until the liquid both outside and inside the floating vessel has the same strength. By repeatedly changing the water in the outer vessel, the whole of the salt might be removed from the solution wdthin the cylinder. On the other hand, if a solution of gum arabic were placed within the parchment drum, and subjected to precisely the same treatment, the gum would be found incapable of diffusion through the membrane. If a mixture of brine and gum were placed in the cylinder wdth parchment bottom, and then floated on the surface of w'ater, the salt w^ould diffuse out and the gum remain behind : in this manner a complete separation of the two might be effected. The separation of bodies by their respective ability or inability, when dissolved, to diffuse through a porous membrane, is termed “Dialysis.” 49. Crystalloids and Colloids. — ^All bodies, soluble in water, are capable of being divided into tw^o great classes, known respectively as “ crystalloids ” and “ colloids.” Crystalloids are substances which, on changing from the liquid to the solid state, assume a crystalline form. Bodies are said to be crystalline when they consist of crystals, and for chemical purposes a crystal may be defined as matter which has spontaneously assumed during the act of solidification a definite geometric form. In crystals there is also a definite internal molecular arrangement related to the crystalline form by certain determinate laws. Solutions of crystalline bodies are usually, but not invariably, free from any marked viscosity. Crystalline bodies are only soluble to a definite extent in water, the quantity dissolved depending more or less on the temperature, as has been already explained Jelly-like substances, as gum and gelatin, are termed “ Colloids,” and do not acquire, a crystalline form when assuming the solid state. The colloids form, wdien treated w^ith water, sirupy, viscous, or jelly-like solutions. They maybe said to be soluble in w^ater in all proportions. Thus, if a few drops of water be added to a piece of dry gelatin, the water will be absorbed by the gelatin, and after a time will be uniformly diffused throughout the wLole mass. Suc- cessive portions of w ater may thus be absorbed by the gelatin, which will become gradually softer, assuming the consistency of a jelly ; further addi- tion of water produces a solution wdth more or less viscosity, depending on the degree of concentration. Crystalloids are especially susceptible of dialysis ; colloids exhibit under similar treatment very little tendency to passthrough a porous INTRODUCTORY. 25 membrane. The probable reason for this inability on the part of colloids is that their solution particles are too large to readily pass through the inter- stices in the porous membrane. The membranes used for dialysis consist of colloid substances : gelatin in the jelly-like form at times is a very con- venient dialysing agent. The apparatus used for the purpose of effecting dialysis is termed a dialyser. The phenomena of liquid diffusion have an exceedingly important bearing on many chemical changes which occur during bread-making. 50. Measures of Weight and Volume. — It will be here convenient to furnish a statement of the different systems of weights and measures usually employed for scientific purposes. The chemist, as a rule, prefers the metric system, as in common use in France, to the very complicated system of weights and measures employed in this country. One reason is that the metric system is extremely simple ; another, that the measures of weight and volume are directly connected with each other. If the authors simply followed their own predilections, metric weights and measures only would be used throughout this work, but it having been strongly represented to them that the introduction of the English equivalents of the different weights employed would be a help to some of their readers, they also have been, in most cases, given. The authors are conscious that the result of this inter- mixture is often incongruous, but to those familiar with the metric system this will present no difficulty, while to those who are unacquainted with it, it mil be an assistance. It is nevertheless urged that the metric system be mastered ; this may be easily done in a quarter of an hour, much time will then be saved which otherwise would have to be spent in making calculations. 51. The Metric System. — The unit of the mstric system is a “ metre,” which is the length of a rod of platinum that is deposited in the archives of France. The metre measures 39*37 English inches. The higher and lower measures are obtained by multiplying and dividing by 10, thus : — Kilometre = 1000 metres = 39370 inches. Hectometre = 100 = 3937 Decametre 10 = 393*7 Metre 39*37 Decimetre = 0*1 metre = 3*937 Centimetre = 0*01 „ = 0*3937 inch Millimetre = 0*001 „ = 0*03937 „ In the above, and all other measures of the metric system, the kilo, hecto, and deca ” are used to represent 1000, 100, and 10 respec- tively ; and “ deci, centi, and milli,” to represent a tenth, hundredth, and thousandth. The decimetre is very nearly 4 inches in length, and the milli- metre very nearly one twenty-fifth of an inch : remembering this, measures of the one denomination can be roughly translated into those of the other. The exact length of a decimetre is shown in Fig. 1. The unit of the measure of capacity is the “ litre,” which is the volume of a cubic decimetre : — Kilolitre Hectolitre Decalitre Litre Decilitre Centilitre Millilitre = 1000 = 100 = 10 Cubic Inches. litres = 61027 „ = 6102*7 „ = 610*27 0*1 litre = 0-01 „ = 0*001 „ = 61*027 6*1027 0*61027 0*06102 Pints. 1760*7 176*07 17*607 1*7607 0*17607 0*017607 0*00176 Fluid Ounces. 35214 3521*4 352*14 35*214 3*5214 0*3521 0*0352 26 THE TECHNOLOGY OF BREAD-MAKING. The decimetre being 10 centimetres in length, it follows that a cubic decimetre must be equal to 1000 cubic centimetres, and that the millilitre has a volume of a cubic centimetre. The name “ cubic centimetre,"' or its abbreviation “ c.c.," is* almost always used in preference to millilitre ; thus, a burette or pipette is said to deliver 50 c.c., while a litre measure is often termed a “ 1000 c.c." measure. A cubic inch is equal to 16*38 cubic centimetres. 1 2 3 4 6 7 8 9 10 The unit of the measure of weight is the “ gramme," or “ gram " ; this is the weight of a cubic centimetre of distilled water at its maximum density : 39*2° F.) Kilogram = 1000 grams = Grains. 15432*3 Avoirdupois Ounces. 35*2739 Hectogram = 100 „ = 1543*23 3*52739 Decagram = 10 „ 154*323 0*35273 Gram = 15*4323 0*03527 Decigram = 0*1 gram = 1*54323 0*00352 Centigram = 0*01 „ - 0*15432 0*00035 Milligram = 0*001 „ = 0*01543 0*0000351 A kilogram is just over 2 lb. oz., and a hectogram is very nearly 3J oz. An ounce avoirdupois equals 28*35 grams. The relation between the weight and volume of water is a very simple one, the volume being the same number of c.c. as the weight is grams. With other liquids the volume in c.c. X specific gravity = weight in grams. Each side of this square measures 1 Decimetre, or 10 Centimetres, or 100 Millimetres, or 3-937 English inches. A litre is a cubic measure of 1 decimetre in the side, or a cube each side of which has the dimensions of this figure. When full of water at 4° C. a litre weighs exactly 1 kilogram or 1000 grams, and is equivalent to 1000 cubic centimetres ; or to 61-027 cubic inches, English. A gram is the weight of a centimetre cube of distilled water ; at 4° C. it weighs 15-432 grains. I Sq. Centim ■< 4 inches. Fig. 1. INTRODUCTORY. 27 52. English Weights and Measures. — ^Familiarity with English weights and measures is assumed, still the following partieulars will most likely be of service — one gallon of pure water at a temperature of 62° F. (16*6° C.) weighs 10 pounds or 160 ounces or 70,000 grains ; the pint, therefore, weighs 20 ounces. The measure termed a “ fluid ounce '' is derived from the weight of a pint of water. A fluid ounce is a measure of volume, not of weight, and equals one twentieth part of a pint. The fluid ounce bears the same relation to the avoirdupois ounce, as does the cubic centimetre to the gram. A gallon is equal to 277*274 cubic inches. An ounce avoirdupois weighs 437*5 grains. CHAPTER II. DESCRIPTION OF THE PRINCIPAL CHEMICAL ELEMENTS AND THEIR INORGANIC COMPOUNDS. 53. Description of Elements and Compounds. — It is intended in this chapter to give a very brief description of those elements and their inorganic compounds, which are more or less directly connected with the chemistry of wheat, flour, and bread, and to which reference may be made in the latter part of this work. Such descriptions as are here given must not be viewed as being in any way a substitute for a careful study of elementary chemistry. It is thought, however, that to many readers, more particularly those who may not have the time for such a systematic course, an account such as is to follow will be found of service. 54. Hydrogen, H2. — This element is a gas, and is the lightest substance known ; it is consequently selected as the standard by which the density of other gases is measured. One litre of hydrogen at N.T.P. weighs 0*0896 gram. Hydrogen has the lowest atomic weight of all the elements, and is therefore also selected as the unit of the modern system of atomic or combining weights. (For certain reasons, the atomic weights are some- times calculated to the basis of 16 00 as the atomic weight of oxygen.) Hydrogen is colourless, odourless, tasteless, and non-poisonous. It is not capable of supporting respiration, and therefore animals placed therein quickly die through lack of proper air to breathe. Hydrogen is inflammable and burns with a pale blue flame ; it does not support combustion. Hydrogen is only very slightly soluble in water. 55. Oxygen, O2. — ^This element is a colourless, odourless, and non- inflammable gas. Its most remarkable feature is that it supports combustion and also respiration. Bodies which burn in ordinary air do so because that substance is a mixture of oxygen and nitrogen ; they burn with much increased brilliancy in oxygen. The respiration or breathing of animals consists of a removal of oxygen from the air, and a return thereto of water vapour and carbon dioxide gas : the activity of oxygen renders it injurious to breathe in a pure state : in air, the nitrogen acts as a diluting agent, without modifying the essential characteristics of the gas. Oxygen is soluble in water to the extent of three volumes of the gas in one hundred volumes of water at 15° C. This quantity, though small, is of vast importance, as it thus sup- ports the life of fishes, and has also a most important action on fermenta- tion. Although oxygen is such an essential to most forms of life, there are some of the lower microscopic organisms towards which it acts as a most energetic poison. Compounds produced by the union of elements with oxygen are termed “ oxides.’" 56. Ozone, O 3 . — ^This body is a gaseous substance consisting of pure oxygen,' but having a density of 24 instead of 16. This is due to there being 3 atoms of the element in the molecule, instead of 2 as in ordinary oxygen. Ozone has a peculiar odour ; and is produced during the working of a fric- tional electric machine, when its smell is recognized. Traces of this gas exist in the air in mountainous districts, and by the seaside. By exposure ELEMENTS AND INORGANIC COMPOUNDS. 29' to a temperature of 237° C. ozone is transformed into ordinary oxygen. Ozone is a powerful oxidizing agent, and is inimical to the growth and development of germ life. Of recent years, ozone has been proposed as a bleaching agent for flour ; its employment for that purpose will be dis- cussed in full at a later stage. 57. Water, HsO.—This most important compound consists of two volumes of hydrogen united to one volume of oxygen, to form two volumes of water-gas or steam. By weight, water contains 16 parts of oxygen to 2 of hydrogen. Water in the pure state is odourless and taste- less ; viewed through thick layers it has a blue colour. At temperatures below 0° C. water exists in the solid state ; on being heated, ice expands until a temperature of 0° C. is reached. At this point the ice begins to melt ; the temperature remains stationary until the whole of the ice is melted, but in order to effect the change from the solid to the liquid con- dition as much heat is required as would be sufficient to raise 79 times the weight of water from 0° to I°C. Ice in melting contracts in [bulk ; 10*9 volumes of ice producing 10 volumes of water. As the ice-cold water is further heated, contraction continues until a temperature of 4° C. is reached : at this point water is at its maximum density, and any given weight of it occupies its minimum volume. With further application of heat the water expands, and also rises steadily in temperature. In metal vessels open to the air, water boils at a temperature of 100° C. Continued heating now converts the whole of the water into steam, but does not raise the tempera- ture. The quantity of heat necessary to convert the whole of the water at 100° C. into steam at the same temperature would raise 537 *2 times the weight of water from 0° to 1°C. Steam in being further heated expands, and may have its temperature raised indefinitely ; steam follows the same law of expansion on increase of temperature as do other gases. Steam, on being cooled, passes through a series of changes which are the exact con- verse of those just described. At all temperatures water gives off vapour, but with much greater rapidity as the temperature approaches the boiling point. This vapour exerts a definite pressure, the pressure increasing steadily with the temperature ; at the boiling point, the pressure exerted by the vapour of Avater is exactly equal to that of the atmosphere ; conse- quently, if the atmospheric pressure be diminished, the boiling point of water, and also that of all other liquids, is lowered. Advantage is taken of this property in many operations in the arts ; thus, in driving off the water from sugar solutions, as in the preparation of malt extract, the boiling is effected in a vacuum, and so the temperature prevented from rising to any great height. On the other hand, by subjecting water to pressure, its boiling point may be raised to any temperature attainable, the only limit being the capacity, for resisting the pressure, of the material of the vessel. The tubes of steam ovens are constructed on this principle — a certain quan- tity of water is sealed up in them, which, on being heated, is converted into steam having a sufficiently high temperature to effect the baking of bread. The boiling point of water also depends on any substances it may have in solution. Salt and other non-volatile bodies raise the temperature of the boiling point, but do not affect that of the steam produced, which immediately falls to 100° C. Admixture of volatile bodies lowers the boiling point ; thus, a mixture of water and alcohol boils at a temperature below 100° C. until the whole of the alcohol has been expelled. 58. Solvent Power of Water. — ^Water is, of ail bodies, pre-eminently the solvent in nature. As a result of this property, water is never found in a state of purity in nature. Even rain is found to have dissolved out 30 THE TECHNOLOGY OF BREAD-MAKING. traces of solid matter that were suspended in the air, while river and spring water is always more or less impure from saline and other matter dissolved from the soil and rocky strata from whence it is obtained. In addition to the solid matter there is also invariably more or less gas held in solution in natural waters. A further account of natural waters, having particular reference to their fitness for bread- making, is given in a future chapter. For chemical purposes all such water is purified by distillation, that is, it is converted into steam, and re -condensed ; the solid impurities then remain behind. This treatment does not, however, free the water from gases or from volatile impurities. For certain purposes, where rigidly pure water is a necessity, special modes of preparation have to be adopted ; these will be described in detail hereafter. 59. Hydrogen Peroxide, H 2 O 2 . — ^In addition to water, there is also known a higher oxide of hydrogen, to which the name of hydrogen per- oxide is given. In the pure state, hydrogen peroxide is a colourless, odour- less, and somewhat sirupy liquid having a peculiar metallic taste. It is extremely unstable, readily giving off oxygen, and leaving a residue of pure water. When diluted with water, hydrogen peroxide is much more stable, and this stability is increased by the addition of a small quantity of acid. But on heating, this solution is changed into water and free oxygen. This readiness to give up oxygen causes the peroxide to be a powerful oxidizing agent, and as such it possesses active bleaching properties. The semi-molecule of hydrogen peroxide, HO, enters into the composition of a large number of compounds, and has received a specific name, hydroxyl. 60. Chlorine, CL. — This element is, at ordinary temperatures, a gas of a greenish yellow colour, with a most pungent, acrid, and suffocating odour and taste. The presence of comparatively small quantities renders air irrespirable. Chlorine is non-inflammable ; but, to a limited extent, supports combustion. Hydrogen burns in it readily, but carbon is incap- able of direct combination with chlorine. Chlorine does not exist in the free state in nature ; it has so great an attraction for hydrogen that it slowly decomposes water, combining with the hydrogen and liberating oxygen in the free state. Water dissolves 2*368 volumes of chlorine at 15° C. ; the solution has a powerful bleaching action on vegetable colours, and also is a most efficient disinfectant. Chlorine forms compounds, termed chlorides,’' with all other elements. 61. Hydrochloric Acid, HCl. — ^This, the only known compound of hydro- gen and chlorine, is a gaseous body. Hydrochloric acid gas is colourless, fumes on coming in contact with moist air, has a most pungent smell, and is neither inflammable nor a supporter of combustion. One volume of hydrogen unites with one volume of chlorine to produce two volumes of hydrochloric acid gas. The gas dissolves readily in water, one volume of which at 15° C. holds in solution 454 volumes of the gas. The concentrated solution fumes on exposure to air, and smells strongly of the gas ; it has an extremely sour taste, and turns litmus solution red. The commercial solution has a specific gravity of about 1 *16, and contains about 33 per cent, (one third) by weight of hydrochloric acid. Hydrochloric acid attacks many of the metals, forming chlorides, with the evolution of hydrogen. Hydrochloric acid and the bases when placed in contact form the salts known as chlorides. Hydrochloric acid and the chlorides may be recognised when in solution by their giving a curdy white precipitate on the addition of dilute nitric acid, and nitrate of silver solution. 62. Chlorides. — Common salt, or sodium chloride, NaCl, is the mo ;t ELEMENTS AND INORGANIC COMPOUNDS. 31 important of the chlorides, and is largely used as an antiseptic or preventa- tive of putrefaction ; its effect during fermentation of dough will be discussed hereafter. Other chlorides, as calcium chloride, CaCU, will be referred to as occasion arises. 63. Bleaching Powder, or Chloride of Lime, CaOCU. — This body is produced by the union of lime (calcium oxide) with chlorine. The addition of almost any acid, even carbon dioxide, is sufficient to effect its decomposi- tion, liberating free chlorine. Chloride of lime is consequently largely used for disinfecting and bleaching purposes. 64. Carbon, C. — This element is only known in the solid state, being incapable of liquefaction or vaporisation at the highest temperatures at our command (except possibly at the highest temperatures of the electric arc). It exists in nature, uncombined with other elements, in two forms or varieties most strikingly different from each other. One of these consti- tutes the gem known as the diamond, the other is graphite, or black lead. Both these bodies are almost pure carbon. Carbon also occurs plentifully as a constituent of animal and vegetable substances, as flesh, bones, fat, wood, leaves, seeds, and the almost numberless bodies that may be obtained from them. Limestone, marble, and chalk rocks contain a large percentage of carbon ; so also does coal, which is essentially fossilised wood. From flesh, bones, wood, and many other substances, carbon may be obtained by heating them to redness in a closed vessel : this form of carbon is termed “ charcoal,” that from bones being “ animal,” and that from wood ‘‘ vege- table charcoal.” Carbon prepared in this manner, or charcoal, is a black substance. The operation of thus heating a substance in a closed vessel to a temperature sufficiently high to effect its decomposition into volatile liquid and gaseous products, with usually, as in this case, a non-volatile residue, is termed “ destructive distillation.” All forms of carbon are in- flammable. When burned with an insufficient supply of oxygen, carbon monoxide, CO, is produced ; with excess of oxygen, carbon dioxide, or CO2, is formed. Charcoal possesses a most remarkable property of absorb- ing and condensing gases within its pores ; thus, freshly-burnt wood char- coal is capable of absorbing about ninety times its volume of ammonia gas. Charcoal also absorbs considerable quantities of oxygen ; and among other gases, those evolved during the putrefaction of animal and vegetable bodies. The gases resulting from putrefaction are largely composed of carbon and hydrogen, and, when thus brought by their absorption within the charcoal so closely in contact with oxygen, are rapidly burned or oxidised to carbon dioxide, water, and more or less of other inodorous and innocuous substances. Charcoal thus acts as a remedy for bad smells, and acts not by masking them by a more powerful odour, but by absorption of the deleterious vapours, and their conversion into harmless products. In this way charcoal is also capable of removing evil smells from water ; for instance, water from a stagnant pond on being shaken up with charcoal loses its disagreeable odour. Not only does charcoal act as an absorbent of gases, but it also removes many colouring matters from solution ; thus, a syrup of dark brown sugar on being shaken up with animal charcoal, and then filtered, may be made almost colourless. These properties of charcoal have led to its finding much favour as a filtering medium for the purification of water ; for this purpose it is, when fresh, of great efficacy, but after a time loses its activity by be- coming saturated with the bodies it is intended to remove. All filters require from time to time to be taken apart, and the filtering medium re- moved and replaced by some fresh and pure material. Charcoal may be renovated by being heated to redness in a closed vessel. With these precautions, charcoal forms one of the best of filtering agents ; but without 32 THE TECHNOLOGY OF BREAD-MAKING attention to continuous cleaning, filters, so far from purifying water, become positive sources of the most serious , and dangerous impurities. Charcoal is frequently used in the laboratory for decolourising purposes. 65. Carbon Monoxide, CO. — This compound is a colourless, odourless and exceedingly poisonous gas. It is formed when carbon dioxide gas passes over or through red-hot charcoal, as it frequently does in a clear coke or charcoal fire. The carbon monoxide thus produced burns with a blue flame on the surface of the Are. Carbon monoxide is also formed, together with free hydrogen, when steam is passed through a red-hot carbon mass, such as a Are of burning coke. The gas is inflammable, and in burning yields carbon dioxide. Carbon monoxide has no action on lime-water. 66. Carbon Dioxide, CO 2 . — This gas plays a most important part in the chemistry of bread-making. It is colourless, has a sweetish taste, and peculiarly brisk and pungent odour. As carbon dioxide is an essential constituent of aerated waters, its taste and smell are familiar, being those perceived on opening and tasting the contents of a bottle of soda-water. Carbon dioxide is neither inflammable, nor under ordinary circumstances a supporter of combustion. The gas is poisonous to breathe, but may be taken into the stomach without injury. Liquids containing carbon dioxide gas in solution are marked by a pleasant brisk flavour. Carbon dioxide has a density of 22, and is 1*527 times as heavy as ordinary air. In the absence of air currents, it consequently has a tendency to remain a considerable time in a layer on the surface of liquids from which it is being evolved, particularly when they are in somewhat confined spaces. Carbon dioxide is soluble in about its own volume of water ; as has already been explained (paragraph 45), when measured by volume the solubility is independent of the pressure to which the gas is subject. Concentrated solutions of carbon dioxide gas in water are prepared by pumping the gas under pressure (some 10 or 12 atmospheres) into a strong vessel, in which it is agitated with water. The solution thus obtained is permanent under pressure, but on its relaxation the carbon dioxide is again liberated in the gaseous state. Carbon dioxide may be obtained in a variety of ways ; the simplest is by the burning of carbon, or organic bodies containing carbon in air or oxygen — C + O 2 = CO 2 . Carbon. Oxygen’ Carbon Dioxide. It is also produced when chalk, limestone, or marble (calcium carbonate) is heated to full redness — CaCOa = CaO + CO 2 . Caloiuni Carbonate. Calcium Oxide (Lime). Carbon Dioxide. Likewise, by gently heating sodium bicarbonate or ammonium carbonate — 2NaHC03 = Na2C03 + H 2 O + CO 2 . Sodium Bicarbonate. Sodium Carbonate. Water. Carbon Dioxide. (NH4)2C03 - Ammonium Carbonate. 2 NH 3 Ammonia. + H 2 O Water. + CO 2 . Carbon Dioxide. Another method of obtaining carbon dioxide is by treating any carbonate with an acid : the following equations represent a few of the principal of such reactions — CaC03 + 2HC1 = CaCL + H 2 O -}- CO 2 . Calcium Carbonate. Hydrochloric Acid. Calcium Chloride. Water. Carbon Dioxid e. *CaC03 + H 2 SO 4 = CaSO, + H 2 O + CO 2 . Calcium Carbonate. Sulphuric Acid. Calcium Sulphate. Water. Carbon Dioxide. Na2C03 2HC1 = 2N‘aCl + H 2 O + CO 2 . Sodium Carbonate. Hydrochloric Acid. Sodium Chloride (Common Salt). Water. Carbon Dioxide. ELEMENTS AND INORGANIC COMPOUNDS. 33 2NaHC03 + H2C4H4O6 = Na 2 C 4 H 406 + 2H2O + CO2. Sodium Bicarbonate. Tartaric Acid, Sodium Tartrate. Water. Carbon Dioxide. Carbon dioxide is also evolved during alcoholic fermentation, and the putrefaction and decay of organic bodies. In addition, carbon dioxide is produced during the respiration of animals, and is an important constituent of the exhaled breath. An aqueous solution of carbon dioxide gas changes the colour of litmus solution from full blue to a port wine tint ; such a solu- tion has feebly acid properties and forms with bases the salts termed car- bonates. The solution in water may be viewed as carbonic acid, H2CO3 ; hence the gas is frequently called carbonic anhydride. Formerly the term acid was applied, by some chemists, indifferently to the anhydrides and their compounds with water ; carbon dioxide then received the name of “ carbonic acid gas,"' by which it is still popularly known. Modern defini- tions of an acid preclude this name being now correctly applied to what are properly termed anhydrides. 67. Carbonates. — ^With the exception of those of the alkalies, all car- bonates are insoluble in water ; many are, however, dissolved by water containing carbon dioxide in solution. The most interesting example of this is the solution of considerable quantities of carbonate of lime in natural waters obtained from the chalk and other limestone deposits. Such waters, although perfectly clear, become turbid on being boiled from fifteen to thirty minutes : the boiling drives off the carbon dioxide, and the calcium carbonate is precipitated in the insoluble state. The formation of car- bonates is exemplified by the passage of carbon dioxide gas into lime water, i.e., a solution of lime in water, CaH202 ; the insoluble calcium carbonate, or carbonate of lime, is produced, and turns the clear solution milky. This forms a useful and convenient test for the presence of carbon dioxide in any mixture of gases. Most carbonates are easily decomposed by the addition of an acid, with the formation of the corresponding salt of the acid used. Several instances of this action have been given when describing methods for the production of carbon dioxide. The acid- or bi-carbonates have one-half only of the hydrogen replaced by a metal ; they may be pro- duced by passing carbon dioxide gas to excess through a solution of the normal carbonates of the alkalies. The bicarbonates are readily decomposed by heat into normal carbonates, free carbon dioxide, and water. 68. Compounds of Carbon with Hydrogen. — ^These are exceedingly numerous ; an account of some of those of most importance will be given when describing the organic bodies more particularly associated with our subject. As a group, they are termed “ hydrides of carbon." 69. Nitrogen, N 2 . — ^This gas constitutes about four-fifths, by volume, of the atmosphere ; it is also a constituent of ammonia, of nitric acid and its salts, and of many animal and vegetable substances. Nitrogen is colourless, odourless, tasteless, non-infiammable, and a non-supporter of combustion. It does not readily enter into combination with other elements, but may be caused to combine with oxygen by passing a sparking or flaming discharge through a mixture of the two. In the free state nitrogen is marked rather by its neutral qualities than by any positive characteristics. In the uncombined state its principal function is that of a diluting agent in the atmosphere. Although 1 ot an active element, nitro- gen forms an extensive series of compounds. 70. The Atmosphere. — ^It has already been stated that the atmosphere consists essentially of oxygen and nitrogen ; these gases are not united in any way, but simply form a mechanical mixture. In addition to the D 34 THE TECHNOLOGY OF BREAD-MAKING. nitrogen and oxygen, air contains small quantities of carbon dioxide, water vapour, and traces of other substances. Subjoined is a table showing its average composition : — Oxygen, O 2 • . . . 20-61 Nitrogen, N 2 . . . . 77-95 Carbon Dioxide, CO 2 0-04 Aqueous Vapour, H 2 O Nitric Acid, HNO 3 • • 1-40 Ammonia, NH 3 . . 1 Traces. Hydrides of Carbon . In f Sulphuretted Hydrogen, SH 2 . . 1 townsjSulphur Dioxide, SO 2 . . j ” Air, freed from moisture and carbon dioxide, percentage of nitrogen and oxygen : — contains the following By Measure. By AVeight. Nitrogen . . . . . . . . 79‘19 76-99 Oxygen 20-81 23-01 100-00 100-00 Argon, and the other members of the allied group of elements, are here included with the nitrogen. They altogether amount to about 0*94 per cent, of atmospheric air. In addition to the bodies already mentioned, air in most localities con- tains germs of microscopic organisms. 71. Ammonia, NH 3 . — ^Traces of this gas, either in the free state or as salts, are found both in air and in water. Its great natural source is the decomposition of animal and vegetable substances which contain nitrogen as a constituent. In this way, ammonia is continually being formed in nature by the decay of refuse nitrogenous matter, such as the urine and excreta of animals, ^nd other bodies. Many nitrogenous vegetable and animal substances also evolve ammonia on being strongly heated ; among these is coal, which thus forms the principal source from which ammonia is now derived. Ammonia is a colourless gas, with a most pungent and characteristic odour : in the concentrated state the gas acts as an irritant poison, but when diluted with air possesses a smell rather pleasant than otherwise. Ammonia does not support combustion, and at ordinary tem- peratures does not burn in air. The gas is very soluble in water ; the solution has the odour of the gas, and constitutes what is commonly known as liquor ammonice ; this must not be confused with the gas condensed by pressure in the absence of water, and which is termed “ liquid ammonia.'’. Ammonia acts as a powerful alkali, neutralising the strongest acids, and restoring the blue colour to reddened litmus. 72. Ammonium Salts. — On the addition of an acid, such as either sul- phuric or hydrochloric acid, to ammonia, the odour disappears, and the acid, as above stated, is found to be completely neutralised. The reaction may be expressed thus : — NH 3 + HCl = NH 4 CI. Ammonia. Hydrochloric Acid. Ammonium Chloride. 2NH3 + H 2 SO 4 = (NH4)2S04. Ammonia. Sulphuric Acid. Ammonium Sulphate. On comparing, in each case, the formula of the resulting compound Avith that of the acid, it will be seen that the group NH 4 replaces the hydrogen ELEMENTS AND INORGANIC COMPOUNDS. 35 of the acid. This compound, NH4, cannot exist in the free state, but occurs in a number of chemical compounds, and can be transferred from one to another without undergoing decomposition. It is consequently viewed as a compound radical, and has received the name “ Ammonium."’ The solution of ammonia in water may then be represented as ammonium hydroxide, NH4HO ; this body, which is alkaline to litmus, is then seen to be analogous to sodium hydroxide, NaHO, the ammonium occupying a corresponding place to the sodium. This is seen the more clearly when a comparison is instituted between the action of the same acid upon each : — NH4HO + HCl = NH4CI + H2O. Ammonium Hydroxide. Hydrocliloric Acid. Ammonium Chloride. Water. NaHO + HCl = NaCl + H2O. Sodium Hydroxide. Hydrochloric Acid. Sodium Chloride. Water. Ammonium is often represented by the symbol “ Am.” instead of NH4. The stronger bases, as lime, CaO, or soda, NaHO, decompose ammonium salts with the liberation of ammonia : — NH4CI + NaHO = NaCl + NH3 + H2O. Ammonium Chloride. Sodium Hydroxide. Sodium Chloride. Ammonia. Water. All ammonium salts volatise on being heated, leaving no residue, unless the acid be non-volatile, in which case the acid remains behind. 73. Oxides and Acids of Nitrogen. — No less than five distinct compounds of nitrogen with oxygen are known. The following is a list of their names and formulae — Nitrous Oxide . . . . . . . . . . . . N2O Nitric Oxide . . . . . . . . . . NO (or N2O2) Nitrogen Trioxide, Nitrous Anhydride . . . . N2O3 Nitrogen Peroxide . . . . . . . . NO2 or N2O4 Nitrogen Pentoxide, Nitric Anhydride . . . . N2O5 Two of these oxides, the trioxide and pentoxide, form acids with water — the acids being nitric acid, HNO3, and nitrous acid, HNO2. The first and last of this series of oxides have little or no connection with our present subject, but the intermediate three are of much interest and importance as being the agents of a successful flour bleaching process. Eor this reason a brief description of their properties is necessary. 74. Nitric Oxide, NO. — ^Formerly, N2O2 was considered possibly to represent the constitution of the molecule of this body, but from its density, the molecule must be regarded as consisting of NO. The N2O2 formula is given above in brackets, in order to show^ the relationship in com- position between this and the other oxides of nitrogen. When nitric acid is added to metallic copper, an abundance of ruddy fumes is evolved ; but if the operation be conducted in a flask fitted in the ordinary way with a thistle funnel and leading tube, the coloured fumes are seen to be sw^ept out of the flask, which soon becomes filled with a colourless gas, wdiich may be collected over w^ater in the pneumatic trough. This colourless gas is nitric oxide. If a gas jar be partly filled with nitric oxide and then oxygen admitted bubble by bubble, a red colour is seen to develop with each introduction. This rapidly disappears, and simultaneously the water rises in the jar. By careful addition of oxygen the wiiole of the gas (assum- ing its purity) may be thus rendered soluble. Nitric oxide is only very slightly soluble in water, and possesses the property of immediately com- bining with free oxygen to produce nitrogen peroxide, NO2. Nitrogen peroxide is a ruddy coloured gas, and is very soluble in w ater. A convenient 36 THE TECHNOLOGY OF BREAD-MAKING. method of preparing nitric oxide consists of allowing nitric acid to drop into a solution of ferrous sulphate, and at the same time passing a current of air through the solution. The air comes over, carrying with it the gas ; the proportion of the latter may be regulated by adjusting the rate at which the nitric acid is allowed to drop into the solution. The following is the nature of the chemical change : — 8HNO3 + 6FeS04 = 2Fe2(S04)3 + Fe2(N03)6 + 2 NO + 4H2O. Nitric Acid. Ferrous Sulphate. Ferric Sulphate. Ferric Nitrate. Nitric Oxide. Water. In the presence of air, the nitric oxide is immediately converted into the peroxide. 75. Nitrogen Peroxide, NO2. — ^At a temperature of 26-7° C., this gas has a density which indicates that about 80 per cent, of its molecules con- sist of N 2 O 4 , the remaining ones being composed of NO 2 . As the tempera- ture of the gas is raised, the density diminishes, and at 140*0° is 23*00, which corresponds to the whole of the gas being dissociated with NO 2 mole- cules. Nitrogen peroxide is absorbed and decomposed by water ; in the presence of ve^y small quantities of the latter nitrous and nit^-ic acids are thus formed : — N2O4 + H2O = HNO3 + HNO2 Nitrogen Peroxide. Water. Nitric Acid. Nitrous Acid. At ordinary temperatures, and with w^ater in excess, nitric acid and nitric oxide are produced thus : — 3NO2 + H2O = 2HNO3 + NO. Nitrogen Peroxide. Water. Nitric Acid. Nitric Oxide. From the ease wdth wLich nitrogen peroxide loses an atom of oxygen and becomes nitric oxide, it is a powerful oxidising agent. Its efficiency as such is greatly increased by the property possessed by nitric oxide of at once combining with free oxygen and again producing nitrogen per- oxide. In this way a very small quantity of nitrogen peroxide, by its succes- sive reductions and oxidations, may act as a carrier of oxygen to a relatively large quantity of oxidisable material. 76. Nitrogen Trioxide, N2O3. — Nitrogen tri oxide is a very unstable compound which can only exist at low temperatures, and readily decomposes into a mixture of nitric oxide and nitrogen peroxide. With water it forms nitrous acid, HNO 2 , and this in turn yields salts known as nitrites. These bodies are fairly stable, and potassium nitrite, KNO 2 , is an example. Nitrites are found in many drinking waters as an intermediate product in the oxida- tion to nitrates of nitrogenous matter that may have been present. 77. Nitric Acid, HNO 3 . — This is by far the most important oxy -compound of nitrogen. Its usual source in nature is the oxidation of animal matter in the soil. The nitric acid thus produced is found in combination with some base, usually as potassium or calcium nitrate. Pure nitric acid is a colourless fuming liquid ; commonly, how^ever, the acid is of a slightly yellow tint, from the presence of some of the low^er oxides of nitrogen. The pure acid lias a specific gravity of 1*52, and mixes with water in all proportions. Nitric acid is a most pow^erful oxidising agent, and attacks most animal and vegetable tissues w4th great vigour. It also freely dissolves most of the metals, forming nitrates. Gold and platinum are not affected by this acid wdien pure, but are dissolved with the formation of chlorides by a mixture of nitric w'ith hydrochloric acid. Reducing agents convert nitric acid into nitrous acid, or some one or more of the oxides of nitrogen containing less oxygen. Under favourable circumstances, nitric acid may even be reduced to ammonia ; that is, the w hole of its oxygen may be removed, and its place occupied by hydrogen. ELEMENTS AND INORGANIC COMPOUNDS. 37 78. Nitrates. — ^The principal of these is potassium nitrate, KNO3. Like nitric acid, the nitrates are powerful oxidising agents. 79. Sulphur, S 2 . — This element, in its common form, is a brittle yellow solid, which burns in air or oxygen with the formation of sulphur dioxide, SO2. The principal interest of sulphur, in connection with our present sub- ject, lies in its compounds. In addition to its occurrence in many inorganic bodies, sulphur is one of the constituents of albumin and other animal and vegetable substances. 80. Sulphuretted Hydrogen, SH 2 . — ^This body is a colourless gas, having a most disgusting odour, resembling that of rotten eggs ; the gas is soluble in water, which at 15° C. dissolves 3*23 volumes of sulphuretted hydrogen. During the decomposition of substances, either of animal or vegetable origin, containing sulphur, sulphuretted hydrogen is one of the bodies evolved ; it is from the presence of this gas that rotten eggs acquire their characteristic odour. Sulphuretted hydrogen is inflammable, and produces water and sulphur dioxide by its combustion. Moist sulphuretted hydro- gen undergoes, in the presence of oxygen, slow oxidation, with the formation of water and deposition of free sulphur : — 2H2S + 02 = 82+ 2H2O. Sulphuretted Hydrogen. Oxgyen. Sulphur. Water. 81. Sulphur Dioxide, SO 2 . — This gas is produced by the combustion of sulphur in either air or oxygen : it is colourless, has a pungent odour, recognised as that of burning sulphur ; is neither inflammable nor a sup- porter of combustion. Sulphur dioxide is soluble in water, which at a temperature of 15° C. dissolves 47 volumes of the gas ; the solution thus formed tastes and smells of the gas, it reddens and Anally bleaches a solu- tion of litmus. Sulphur dioxide is one of the most powerful antiseptics known. The gas is easily condensed to the liquid state by either cold or pressure. Liquid sulphur dioxide is supplied commercially in syphons, similar to those used for soda water. 82. Sulphurous Acid, H2SO3, and the Sulphites. — Sulphur dioxide when dissolved in water produces a somewhat unstable acid, H2SO3. The sul- phites, or salts of this acid, are mostly insoluble in water, the principal exceptions being sodium sulphite, Na2S03, and potassium sulphite. In addition to the normal sulphites, acid or bisulphites occur ; these may be produced by passing excess of sulphur dioxide into a solution of the normal salts. The bisulphites readily evolve sulphur dioxide on being heated. Calcium sulphite is insoluble in water, but dissolves in a solution of sul- phurous acid, forming calcium bisulphite, or, as commonly called, “ bisulphite of lime."" Bisulphite of lime is largely used as an antiseptic. Under the influence of oxidising agents, sulphurous acid and the sulphites are oxidised to sulphuric acid and sulphates. 83. Sulphuric Acid, H 2 SO 4 , and the Sulphates. — Sulphuric acid is one of the most useful chemical compounds known, forming as it does the start- ing point in the manufacture of a number of substances of vast importance in the arts. When in the pure state, sulphuric acid is a colourless, odourless liquid of an oily consistency : this latter property has led to its receiving the popular name of “ oil of vitriol "" ; the acid, however, is in no way con- nected chemically with the class of bodies known as fats or oils. Sulphuric acid is nearly twice as heavy as water, having a specific gravity of I *842 ; it boils at a temperature of 338° C. Sulphuric acid has a great attraction for water, with which it combines to form definite hydroxides (Le. chemical ^compounds with water) ; considerable heat is evolved during the act of 38 THE TECHNOLOGY OF BREAD-MAKING. union. In consequence of this affinity for water, sulphuric acid is largely used as a desiccating or drying agent ; on exposure to the air the acid rapidly increases in weight by absorption of water vapour, and the air becomes dry ; hence, if a vessel of sulphuric acid be placed under a bell jar, it speedily produces a dry atmosphere inside. Less concentrated varieties of the acid form staple articles of commerce. Owing to this attraction for water, sulphuric acid is a most corrosive body ; wood, paper, and most vegetable and animal substances are vigorously attacked by it ; the acid combines with the hydrogen and oxygen of the substance in the proportions in which they form water, and leaves behind a mass of carbon, together with any excess of either hydrogen or oxygen that may have been present. This, of course, does not in all cases represent the whole of the chemical action that may have occurred. Dilute sulphuric acid contains water in excess, and therefore does not exhibit this dehydrating tendency when placed in contact with other bodies ; it is well to remember this, because in a number of reactions, where dilute sulphuric acid is employed, it produces not merely less energetic action, but action absolutely opposite in character to that of the concentrated acid. The dilute acid, if allowed to evaporate in contact with paper, etc., acts in a similar manner to the strong acid, as the water dries off. Sulphuric acid forms a normal and an acid series of salts, of which Na2S04, sodium sulphate, andNaHS04, acid sodium sulphate, are, respect- ively, examples. Most of the sulphates are more or less soluble in water ; calcium sulphate is only slightly so ; barium sulphate is insoluble in water and dilute acids. Sulphuric acid and the sulphates may be detected in solution by the addition of hydrochloric acid and barium chloride, when they produce a white precipitate of BaS04. 84. -Bromine, Bfs ; Iodine, I 2 ; and Fluorine, F 2 . — These three elements are very closely allied in properties to chlorine ; they have no very intimate connection with the chemistry of wheat and flour. Bromine is a liquid ; iodine, at ordinary temperatures, is a solid body. Iodine is slightly soluble in water, readily soluble in alcohol or a solution of potassium iodide, KI. Iodine, or its solution, produces a characteristic blue colour with starch : this reaction is of great delicacy, and is an exceedingly valuable test both for starch and iodine. Fluorine forms an acid with hydrogen, hydrofluoric acid, HF, which is characterised by its power of attacking and dissolving glass and the silicates generally. 85. Silicon, Si ; Silica, Si02 ; and the Silicates. — Silicon is an element somewhat resembling carbon in some of its properties ; all that at present need be stated about it is that it forms with oxygen an oxide, Si02, analogous in composition to that of carbon, CO2. This oxide, Si02, is termed silica, or at times, silicic anhydride. Flint and quartz are almost chemically pure forms of silica ; in this form silica is insoluble in water and all acids, and mixtures of acids, except hydrofluoric acid. On being fused with an alkali as KHO, or an alkaline carbonate, K2CO3, silica produces a glassy substance entirely soluble in water : this body is potassium silicate, K4Si04, and from it, silicic acid, H4Si04, may be obtained. Silicic acid is soluble in water and is tasteless and odourless ; on being gently evaporated it first forms a. jelly, and then, as the whole of the water is driven off, the silica remains as a white powder, once more insoluble in water and acids. As silica produces a compound Avith water which, by action on bases, forms salts, silica is rightly viewed as an anhydride. The silicates are the principal constituents of the great rock masses of the earth and of soil. The natural silicates, usually contain two or more of the following bases — iron oxides, alumina, lime, magnesia, potash, and soda. With the exception of those of potash and soda, the silicates are mostly insoluble. ELEMENTS AND INORGANIC COMPOUNDS. 39 86. Phosphorus, P4 ; Phosphoric Acid, H3PO4 ; and the Phosphates. — Like several other elements, phosphorus assumes more than one distinct form. The commoner variety is a crystalline body, often called yellow phosphorus. In addition there is an amorphous variety, which from its colour is frequently known as red phosphorus. In properties, the ordinary or yellow phosphorus is one of the most striking of the elements ; its attrac- tion for oxygen is so great that it has to be kept under water in order to prevent its oxidation. In process of manufacture, the ordinary phosphorus is usually cast into sticks of a light yeUaw colour and the consistency of wax ; a piece of phosphorus appears luminous in the dark when exposed to air ; this is caused by its slow combustion. A slight elevation of temperature, or even friction, suffices to cause phosphorus to burn vigorously ; it then produces a vivid light, and forms, by union with oxygen, phosphorus pent- oxide, P2O6, or, as it is sometimes termed, phosphoric anhydride. Phos- phoric anhydride, as thus formed, is a white powder, which combines with water with great avidity to form phosphoric acid, H3PO4. Phosphoric acid is principally of interest because of its salts, known as phosphates : of these the most important to us are calcium phosphate, Ca3(P04)2 ; and potassium phosphate, K3PO4. Calcium phosphate is the principal constituent of the mineral matter of bones, and hence in some form or other is an absolutely essential article of food. Phosphates occur in some parts of all plants, and is derived by them from the soil. In wheat, the phosphoric acid is mostly combined with potassium. The alkaline phosphates are soluble in water ; the others are insoluble, but may be readily dissolved by the addition of nitric or hydrochloric acid. 87 . The Metals and their Compounds. — ^Within the limits of this work it would be impossible to give even the briefest systematic description of these bodies. An account follows of calcium and potassium, but such other metallic compounds as have any bearing on our subject will be described when reference to them is made. 88. Calcium, Ca, and its Compounds. — ^Until recently, calcium was scarcely more than known in the free state. It is a silver- white metal, and has such an attraction for oxygen that it very readily becomes oxidised on exposure to moist air, with the formation of calcium oxide. There are two oxides of calcium, but only the monoxide is of practical importance in con- nection with the present subject. This body, CaO, is that commonly spoken of as “ quicklime."’ The salts of calcium are sometimes referred to as salts of lime ; this is not strictly correct, but in most cases makes no real differ- ence. To this there is one exception. Chloride of calcium, or calcium chloride, is CaCb ; chloride of lime is a very different body, CaOCL. Cal- cium oxide is a whitish-grey substance, usually obtained by the action of heat on the carbonate ; it is infusible at the highest temperatures. Calcium oxide combines readily with water, with the evolution of considerable heat, forming slaked lime, or calcium hydroxide, CaH202. Calcium hydroxide occurs as a dry, white powder, which is soluble in water to the extent of one part in 600. This solution is that known as “ lime-water,” and is employed as a test for carbon dioxide. The solution of lime has a decidedly alkaline reaction, turning reddened litmus blue. Calcium produces an extensive series of salts ; of these calcium carbonate has been already referred to when describing carbon dioxide. The next most important salt is calcium sulphate ; this body is only slightly soluble, one part being dissolved by about 400 parts of water. The phosphate and chloride have already been referred to ; the latter has a great affinity for water, and consequently is 40 THE TECHNOLOGY OF BREAD-MAKING. often used as a drying agent ; it can be frequently used where sulphuric acid would be unsuitable from its other properties. 89. Potassium, K, and its Compounds. — Potassium is a soft bluish white metal, which has so great an attraction for oxygen that it has to be kept from contact with the air, and even liquids as water, which contain oxygen as one of their compounds ; for this purpose the potassium is gener- ally preserved in mineral naphtha, a compound of carbon and hydrogen. The normal oxide of potassium is K2O ; this body has such affinity for water that it practically never occurs in the anhydrous state, but usually as the hydroxide, KHO. Potassium hydroxide is a white crystalline solid sub- stance ; it melts at a red heat, and is supplied commercially either in sticks, or in lumps produced by breaking up fused slabs of the compound. Potas- sium hydroxide is a powerfully caustic body, and rapidly destroys animal tissues. It is one of the most powerful alkalies known, restoring the blue colour to reddened litmus, and forming salts with acids. Potassium hydro- xide decomposes ammonium salts with the liberation of ammonia ; sodium hydroxide and lime behave similarly in this respect. Potassium hydroxide is very soluble in water ; the solution has a peculiar soapy feel to the fingers. Potassium hydroxide has a great attraction for carbon dioxide ; its solution absorbs that gas with great rapidity, forming potassium carbonate, K 2 CO 3 . Potassium carbonate is a white deliquescent body ; i.e. one that readily becomes moist through the absorption of water . Like other de- liquescent bodies, potassium carbonate is very soluble in water ; the solution is strongly alkaline to litmus, although the salt is of normal constitution. As already explained, the very strong bases produce with certain weak acids normal salts, in which the alkaline compound may be said to predominate. Potassium carbonate was at one time almost exclusively obtained from wood ashes. An acid potassium carbonate, KHCO 3 , is also kno^vn ; this body is neutral to litmus, and is less soluble in water ; it is at a temperature of 80° C. decomposed into the normal carbonate and free acid. 90. Sodium Compounds. — Sodium forms a series of compounds which closely resemble those of potassium ; of these the most familiar are sodium hydroxide, NaHO ; sodium carbonate, Na2C03 ; acid sodium carbonate, NaHC03 ; and sodium chloride, NaCl. Sodium hydroxide is a somewhat less powerful base than potassium hydroxide. CHAPTER III. DESCRIPTION OF ORGANIC COMPOUNDS. 91. “ Organic ” Chemical Compounds. — Chemical science is commonly divided into two branches, known respectively as “ Inorganic "" and Or- ganic chemistry. Certain substances, whether they occur in nature, or are prepared in the laboratory, are obtained from mineral sources : the bodies described in the preceding chapter are instances of such compounds. There are, on the other hand, bodies which are obtained either from the animal or vegetable kingdom. Animals and vegetables are organised bodies, that is, they have definite organs which adapt them for that series of pro- cesses which constitutes what is called “ life "" ; hence chemical compounds having a vegetable or animal origin are termed “ organic.'' Those which are not thus obtained from organic sources are termed “ inorganic ” com- pounds : the two names have also been given to the branches of chemistry which treat respectively of these two classes of bodies, and of their properties and reactions. It was formerly supposed that the so-called organic bodies could only be obtained from organic sources ; but chemical investigation has demonstrated that many such compounds can be produced by artificial means from the elements of which they are composed, without the inter- vention of living organisms, and even under such conditions as render the existence of living organisms an impossibility. Alcohol and its derivatives are examples. The definition of an organic body as one produced as a result of “ life " is evidently no longer tenable, and chemists have en- deavoured, with more or less success, to frame new definitions of organic chemistry. As all organic compounds contain carbon, it has been proposed to define it as the “ chemistry of the carbon compounds " ; again, as many organic bodies are w^eU defined compound radicals, the phrase, “ chemistry of the compound radicals " has been proposed. These definitions have not been found entirely satisfactory, as they are either too wide or too narrow. They present the further difficulty that they are not modifications or ex- planations of the term organic chemistry, but are totally new phrases. As this branch of chemistry is still called organic chemistry, and the compounds included in its scope are still called organic compounds, the student of the chemistry of bread- making may regard Organic Chemistry as that branch of the science which treats of the composition and properties of those compounds whose usual or original source is or was either animal or vegetable. This explanation of the meaning of organic chemistry has the defect that it does not include all those substances now known as organic compounds ; but all such com- pounds thus excluded are without any direct bearing on the chemistry of wheat, flour, or bread. 92. Organised Structures. — ^Although organic compounds can be prepared by artificial means, it must be clearly understood that no chemical processes have as yet been found capable of producing an organised structure ; furl her, all evidence hitherto obtained, so far as it goes, tends to prove the impossibility of such structures being formed other than through living agencies. Eor instance, starch is found, when viewed under the microscope, to have a 41 42 THE TECHNOLOGY OF BREAD-MAKING. structural organisation peculiar to it self. Starch may be dissolved, and after such solution again obtained in the solid state ; but the solid thus produced shows no traces of the original structure of the grains of starch ; neither is there knovTi any artificial process by which the starch may again be built up into structures of the same kind as those in which it originally occurred. Similarly, it is impossible to artificially produce a blood corpuscle. The same law applies to minute organisms, as yeast, bacteria, etc. ; none of these can be generated otherwise than through the agency of previously existing living beings of the same type. So far as any problem can be proved scienti- fically, this fact of the impossibility of spontaneous generaticn is abundantly demon- strated ; experimental evidence of a most conclusive character has shown as certainly as scientific research can, in any case, possibly show, that living organisms can only be formed by means of similar pre-existing organisms. 93. Composition of Organic Bodies.— Organic compounds, generally, have a much more complicated chemical composition than have inorganic compounds ; they are mostly, however, restricted to comparatively few elements. All organic bodies contain carbon ; many are composed of carbon and hydrogen only, a greater number consist of carbon, hydrogen, and oxygen ; while others contain the four elements, carbon, hydrogen, oxygen, and nitrogen. The majority of organic compounds belong to one or other of these series. Carbon, more than any other element, is remark- able for the property of, in compounds, combining directly with itseK, and so forming most complicated bodies out of comparatively few' elements. 94. Classification of Organic Compounds. — The number of these is so bewildering that, without some classification, it would be impossible to grasp their relationship to each other : recent chemical science has suc- ceeded in very clearly demonstrating the constitution of a vast number of these bodies. There are, in the first place, large numbers of well defined compound radicals, consisting of carbon and hydrogen : it has been found possible to group these into distinct families, the members of each of which may be represented by a common formula. 95. Organic Radicals. — ^The most important series of these is that known as the “ Methyl,’' or “ Ethyl ” series ; these have the common formula (C„H2„4 .i) 2- This formula signifies that in the first place the molecule con- sists of two semi-molecules that are similar in composition ; secondly, that in each semi-molecule the number of atoms of hydrogen is one more than double the number of atoms of carbon. The following is a list of a few of the radicals of this series : — Methyl Ethyl Propyl Butyl Amyl . Caproyl . . Mea Eta Pr2 Bua Ay2 0P2 CH3 CH3 C2H5 C2H5 ’ C3H7 C3H, ’ C4H, C4H9 C5H,, C5H,, CeHjg C6H,3 or or /CH3\ f CMeHa VCHa\’ ""i CMeHa f CEtHa I CEtHa or Each semi-molecule of these radicals behaves in compounds as though it were an atom of a monad element ; the atomicity is shown by the follow- ing graphic formulae — ORGANIC COMPOUNDS. 43 H H H I I I H— C— H— C— C— H H H Methyl. Ethyl. Irom these formulae it is seen that in each case there is one of the carbon bonds free ; in the free state two semi-molecules unite by these bonds to form the molecule. The graphic formulae also show how each of the higher radicals of the series may be viewed as compounds of the next lower radical with an additional CH2. The temperature of the boiling points of these bodies increases as the series is ascended. 96. Hydrides of Organic Radicals (Paraffin Group). — ^These bodies are compounds of the radicals with hydrogen ; those of the series already re- ferred to have the general formula C„H2„+2. Among them there is, as the lowest, methane or methyl hydride (marsh gas), CH3H or CH4 ; from this the series ascends regularly to C^gH3 4. These compounds are distinguished by their not being readily attacked by the most powerful oxidising agents, they consequently have received the name of “ paraffins (from the Latin, 'parum affinis, having little affinity). The lower members of the series are gases, the middle are liquids, and the higher members are solid at ordinary temperatures. The paraffins are produced by the destructive distillation of wood, coal, and many other organic substances, and also occur in rock- oils. Some varieties of American petroleum consist almost entirely of paraffins. In distilling the crude petroleum, it is found that the tempera- ture of the vapour produced rises as the operation progresses. The more volatile portions distil oh first ; the distillate may be collected in separate portions or fractions ; the operation is then termed “ fractional distilla- tion.'" The lighter or more volatile paraffins constitute what is known as light petroleum spirit ; this substance, when carefully freed from solid im- purities, is of great use as a solvent for fatty substances, both in the arts and chemical analysis. Good light petroleum spirit should distil entirely at a temperature of 70 ° C. Such spirit is a mixture of several of the lower paraffins. The petroleum of commerce consists of a somewhat higher fraction, and mineral lubricating greases and “ vaseline ” of a yet less vola- tile portion. The least volatile portion of all constitutes, when pure, the hard white solid substance knovTi as “ solid paraffin," or paraffin “ wax." 97. The Alcohols. — ^In constitution, these bodies bear the same relation to the organic radicals as do the metallic hydroxides to the metals. This is clearly seen on writing representative formulae of the two side by side : — C2H5HO NaHO Ethyl, or ordinary, Alcohol. Sodium Hydroxide. Certain chemists carry this analogy so far as to regard " the alcohols as hydrates (hydroxides) of the radicals, and term ordinary alcohol, “ ethylic hydrate." To this the objection has been taken that the alcohols do not contain water, and that the hydroxides are really hydrated oxides, or oxides formed by the union of water with the normal oxide, as, for example : — Na 20 + H2O = 2 NaHO. The argument is, however, addressed to the composition of these bodies rather than to the mode of formation ; and it is clear that these bodies may be regarded as compounds of the organic radicals with hydroxyl (HO). 44 THE TECHNOLOGY OF BREAD-MAKING, It is then simply a matter of definition whether or not the term hydrate or hydroxide shall be understood to mean a compound with hydroxyl. The alcohols are sometimes conveniently regarded as substitution products of the paraffins ; thus ethyl alcohol may be viewed as ethane, C 2 Hg, in which hydroxyl is substituted for one of the atoms of hydrogen. In this manner the relationship between the alcohols and the paraffins is clearly seen. Like metallic hydroxides, the alcohols enter into combination with acids to form organic salts. Thus ethyl alcohol, being C 2 H 3 HO, is converted by the action of hydrochloric acid into C2H5CI, ethyl chloride. This reaction is analagous to that by which sodium hydroxide is converted into sodium chloride, as is shown by the respective equations ; — C 2 H 5 HO -f HCl = C 2 H 5 CI + H 2 O. Alcohol or Ethyl Hydroxide. Hydrochloric Acid. Ethyl Chloride. Water. NaHO + HCl = NaCl + H 2 O. Sodium Hydroxide. Hydrochloric Acid. Sodium Chloride. Water. Of the various alcohols, those of the methyl series are the most important, and are represented by the formula, C„H 2 ,j+iHO. Subjoined are a few examples of these compounds : — Methyl Alcohol, CH3HO, or | cH^HO. Butyl Alcohol, C4H9HO. Ethyl „ CAHO,or{CH3jjo Propyl ,, C3H7HO. Melissic „ CaoHgiHO. The lower members of the series are liquid, and the higher solid. 98. Methyl Alcohol, CH3HO. — ^This body, in an impure form, is yielded on the destructive distillation of wood, and hence is commonly known as “ wood spirit,'' or “ wood naphtha." This crude preparation has a nauseous flavour, which renders it unfit for drinking : the pure methyl alcohol has, on the contrary, a purely spirituous taste and odour. Methyl alcohol mixes in all proportions with water, ethyl alcohol, and ether ; it has at 15° C. a specific gravity of 0*8021. 99. Ethyl Alcohol, | or C 2 H 5 HO. — ^This body constitutes the active ingredient of beer, wine, and of all spirituous liquors, as brandy, whisky, etc. The term “ alcohol," when used without any prefix, is always understood to refer to this compound, which is known popularly as “ spirits of wine." Alcohol may be produced artificially from its elements by purely chemical means, but is always manufactured by the process of fermentation, of which a detailed account is hereafter given. Pure ethyl alcohol is a colourless, mobile liquid, having an agreeable spirituous odour, and a burn- ing taste. Alcohol is inflammable, and burns with a scarcely luminous smokeless flame, evolving considerable heat ; it is on this account largely used in “ spirit " lamps as a fuel. Alcohol rapidly evaporates at ordinary temperatures, and when pure, boils at 78*4° C. (= 173*1°) F. . At a tem- perature of 15*5° C., alcohol has a specific gravity of 0*79350 ; that of water, at the same temperature, being taken as unity. Alcohol mixes with water, and also ether, in all proportions : for the former compound it has a great affinity, and evolves considerable heat on the tw^o being mixed ; the volume of the mixture is less than that of the two liquids taken separately. As previously mentioned, alcohol is manufactured by fermentation ; this pro- cess is only f apable of producing a comparatively dilute solution of alcohol in water. In order to obtain a stronger spirit, the fermented liquid is dis- ORGANIC COMPOUNDS. 45 tilled ; as alcohol boils at a lower temperature than water, the earlier por- tions of the distillate are the stronger in spirit, until finally no alcohol re- mains in the liquid being distilled. It is not possible to obtain in this manner alcohol free from water, as even the very first portions of spirit which distil over carry water with them. By several times distilling the spirit it is possible to obtain a mixture containing about 90 per cent, of the pure spirit ; special distilling arrangements have resulted in the production of a distillate containing as much as 95 per cent, of alcohol. In order to remove this small quantity of water, the spirit is treated with quicklime or potassium carbonate, and then allowed to stand, and after a time distilled : in this manner alcohol can be obtained in which there is only the most minute trace of water. This desiccated alcohol is termed “ absolute ” alcohol. Alcohol is of very great use as a solvent, particularly for many organic bodies ; it also acts as an antiseptic, and hence is employed for the preser- vation of biological and other specimens. The solvent power of alcohol is modified considerably by its admixture with more or less water : for many purposes alcohol of a certain definite strength is necessary. As water and alcohol have different densities, and as density is easily measured, it is a usual method of testing the strength of alcohol to take its specific gravity. Tables have been prepared giving the strength in percentages of alcohol present for different densities. Three distinct standards of strength of alcoholic spirit are commercially recognised. The “ rectified spirit of wine of the British Pharmacopoeia is the strongest spirit that can be produced by the ordinary methods of distillation : such spirit should contain 84 per cent, by weight of absolute alcohol, and should have a density of 0*838. “ Proof spirit ” is a term that has survived its original application : it is now legally defined as spirit of such a strength that 13 volumes of it shall weigh at 51° F. the same as 12 volumes of water at the same tempera- ture. Proof spirit has at 15°5°C. a density of 0*91984, and contains 49*24 l^er cent, by weight of alcohol and 50*76 of water. Weaker spirits are de- fined as being so many degrees “ under proof (U.P.), while stronger spirits are referred to as being so many degrees “ over proof "" (O.P.). A spirit of 10 degrees U.P. is such that it contains 90 per cent, of proof spirit and 10 per cent, of water ; spirit of 10 degrees O.P. is of such a strength that it may be made up to 110 volumes by the addition of water, and Avould then have the same percentage of alcohol as proof spirit. Absolute alcohol is that, as before s ated, which contains no water. For chemical purposes it is usual to specify the strength of alcohol, either as so much per cent, spirit, or by its density. When for any purpose it is directed that alcohol of a certain strength must be employed, particulars will be given as to its density ; for complete tables of densities and corresponding strengths, the larger treatises on chemistry must be consulted. 100. Detection of Alcohol. — ^Alcohol when present in any quantity is easily recognised by its smell ; in liquids which contain traces only, it is best to distil and then examine the first portions of the distillate. When using a Liebig’s condenser, it will be seen, at the point where the vapour begins to condense, that when alcohol is present, the distillate trickles down the sides of the tube in peculiar oily looking drops or “ tears.” This appear- ance ceases as soon as the whole of the alcohol has distilled off. Very minute quantities of alcohol suffice to produce this effect. Another and more delicate method for its detection depends on the production of iodo- form. This body has the symbol CHI3, and is similar in constitution to chloroform, CHCI3. The liquid under examination should first be distilled, and the tests applied to the first portion of the distillate. Ten c.c. are to be taken and rendered alkaline by the addition of about a quarter of a c.c. 46 THE TECHNOLOGY OF BREAD-MAKING. (five or six drops) of a 10 per cent, solution of sodium hydroxide ; the liquid must next be warmed to about 50° C., and then a solution of potas- sium iodide, saturated with iodine, added drop by drop until a slight excess of free iodine is present ; this is indicated by the liquid acquiring a per- manent sherry yellow tint. The liquid must next be just decolourised by the addition of a minute quantity of the sodium hydroxide solution. If there be any alcohol present, a yellow crystalline precipitate of iodoform gradually forms. Certain other organic compounds, however, are capable of pro- ducing the same reaction. 101. Methylated Spirits of Wine. — ^Alcoholic liquors are subject to a high duty ; consequently, for purposes other than the production of drink- able spirits, the Excise authorities permit the sale, duty free, of a mixture of rectified spirit with some substance which imparts a flavour sufficiently nauseous to render the whole absolutely undrinkable, except to the palates of the most debased dipsomaniacs. Formerly spirit was thus “ denatured ” by the addition of one volume of commercial wood spirit to nine volumes of rectified spirit. Being produced by the addition of crude methyl alcohol, the mixture was known as “ methylated spirits of wine.'’ Other bodies are now used for “ methylating," among them being some of the lighter paraf- fins. For most laboratory operations, methylated spirits can be used as a substitute for rectified spirits of wine : for delicate purposes it is well to re-distil the spirits prior to use. On diluting the distilled spirit to about 70 per cent, strength, opalescence is produced. This is due to paraffin Avhich distils over, and is insoluble in the mixture of spirit and water. As the cloudiness is due to the presence of a volatile substance, it does not interfere with many, or even most, uses to which the spirit is applied. Methylated spirits may be rendered almost absolute by adding about one- third of its weight of recently burned quicklime, and thoroughly shaking ; the mixture must be allowed to stand some three or four days, and the shaking repeated two or three times daily. The spirit must then be dis- tilled, precautions being taken to prevent the temperature unduly rising. The still should be fixed in a water bath, consisting of an iron saucepan containing brine. The clear portions of the spirits should first be poured into the still, without disturbing the sediment, and distilled to dryness by application of heat to the water bath. Care must be taken that the bath does not boil dry. The pasty mass of lime may next be placed in the still, preferably in small quantities at a time, and heated by the bath so long as any alcohol distils over. An efficient condensing worm must be used, and the tube connecting it with the still ought to be a long one. At the close of the operation the lime may be removed from the vessel used as a still by soaking with water. 102. Propyl, Butyl, and Amyl Alcohols. — These bodies are produced in small quantities during fermentation. They all boil at a higher tempera- ture than ethyl alcoliol, and are found in the residual liquor after most of tlie spirit has been distilled over. Propyl alcohol occurs in the residues of the distillation of the fermented liquor of the marc of grapes in the produc- tion of low-class brandy. Normal butyl alcohol occurs in genuine cognac, from. which it may be obtained by fractional distillation : it has a boiling point of 116*8° C., and possesses an agreeable odour. But spirits from potatoes, beet-root, maize, and certain other substances contain isobutyl alcohol, an isomeride of the normal alcohol. Isobutyl alcohol has a dis- agreeable fusel-oil-like odour. The following formulae indicate their differ- ence in constitution : — ORGANIC COMPOUNDS. 47 /^TJ /^TT ^CHs L^xl2L'Xl2'^-tl3 0x1 CH 2 H 0 CH 2 H 0 Normal Butyl Alcohol. Isobutyl Alcohol. In addition to isobutyl alcohol, amyl alcohol is also produced as a bye- product during the manufacture of alcohol from potatoes or grain. Amyl alcohol is an oily looking liquid, which does not mix with water, but with alcohol and ether in all proportions ; it boils at 137° C. Amyl alcohol has a strong, disagreeable smell, and burning taste. Its intoxicating effects are similar to those of ethyl alcohol, but a small quantity of amyl alcohol suf- fices to produce all symptoms of intoxication ; it has been estimated that amyl alcohol is fifteen times as intoxicating as is ethyl alcohol. 103. Fusel or Fousel Oil. — ^This name is applied to the oily mixture of spirits above referred to as being formed during fermentation. The fusel oil of potato and grain spirits principally consists of amyl alcohol. 104. Glycerin, C 3 H 5 (HO) 3 .— In constitution this body is an alcohol, and may be regarded as the paraffin propane, C 3 H 8 , in which three of the hydrogen atoms have been replaced by three groups of hydroxyl. When pure, glycerin is a colourless, odourless, and thick sirupy liquid, having a sweet taste, and boiling at a temperature of 290° C. Glycerin is one of the substances produced during the normal fermentation of sugar, and also is the basic constituent of fats and oils. 105. Mannitol, C6H8(HO)6 . — This is a substance possessing a sweet taste and found in the sap of certain plants, which sap when dried consti- tutes what is known as manna. In constitution mannitol is a hexahydric alcohol, and is of interest from its relationship to the sugars and other carbohydrates. Mannitol is regarded as being derived from the paraffin hexane, CgH^^, by the replacement of six atoms of hydrogen by six hydroxyl groups. 106. The Ethers. — These bodies are the oxides of the organic radicals : ( C H term “ether'' is employed without any qualification, it is this body to which reference is made. From its mode of preparation, ether is often termed “ sulphuric ether " ; sulphuric acid, of course, does not enter into its composition. Ether is a colourless, very mobile liquid, having a peculiar, penetrating, and characteristic smell. This smell has given rise to the term “ ethereal odour." Ether has a specific gravity of 0*736, it does not mix with water ; but, on being added, forms a layer on the surface. The ether dissolves a certain quantity of water, while the water, on the other hand, holds a portion of the ether in solution. Ether boils at 34*5° C., and is very volatile at ordinary temperature. The vapour is inflammable ; and, as may be gathered from the formula, is very heavy. Great care must be taken when working with ether to keep all lights at a safe distance. The high density of the vapour causes it to flow as a dense layer along a level surface for a considerable distance ; in this way there is danger of the vapour communicating with a light that may be placed even at the further end of a long table. The rule should invariably be adopted of having no more of the liquid in the immediate neighbourhood, where experiments are being made, than is necessary for the purpose in hand ; the store bottle should not be kept in the laboratory. Ether is of great use as a solvent for fats, resins, and other organic bodies. 48 THE TECHNOLOGY OF BREAD-MAKING. 107. Esters or Ethereal Salts. — ^These bodies are produced by the displace- ment of the hydrogen of acids by organic radicals ; the acid may be organic or inorganic. The compounds of such radicals, with chlorine, bromine, and iodine, are at times viewed as a sub-class of these bodies, and are termed “ haloid '' esters. The esters were at one time called “ compound ethers,'^ but the newer name “ester is now employed in order to differentiate them from the true ethers or oxides of organic radicals. The following are formulae of examples of esters : — C2H5CL C2H5C2H3O2. C5H^iC2H302. Ethyl Chloride. Ethyl Acetate. Amyl Acetate. NaCl. NaC2H302. Sodium Chloride. Sodium Acetate. NaC2H302. Sodium Acetate. The corresponding sodium salts are written underneath in order to show their similarity in constitution. Amyl acetate is the confectioner’s well- known jargonelle pear flavouring, while pineapple essence consists of an- other ester, ethyl butyrate, C2H5C4H^02. On appropriate treatment with sodium hydroxide, the esters are split up with the formation of a sodium salt, thus*: — C2H5C2H3O2 + NaHO = NaC2H302 + C2H5HO. Ethyl Acetate. Sodium Hydroxide. Sodium Acetate. Alcohol (Ethyl Hydroxide). The reaction is similar to that of sodium hydroxide on a weaker inorganic base, as ammonium : — NH4CI -f NaHO = NaCl + NH4HO. Ammonium Chloride. Sodium Hydroxide. Sodium Chloride. Ammonium Hdyroxide. 108. Chloroform, CHCI3. — In a number of organic compounds it is possible to replace the atoms of certain elements present by those of others ; in this way what are called “ substitution products ” are formed. Starting with methyl hydride, CH4, the hydrogen of this body may be replaced atom by atom by chlorine until CCI4 is formed. The replacement of three atoms of hydrogen by chlorine results in the production of chloroform, CHCI3. This compound is at ordinary temperatures a heavy volatile liquid, having a specific gravity of 1*48. The vapour of chloroform has a peculiar but pleasant smell, and when inhaled produces insensibility to pain, while in less quantities it causes stupefaction. No danger need, however, be appre- hended during any ordinary working with this substance. Chloroform boils at a temperature of 60 *8° C. Chloroform, like ether, acts as a solvent of many organic bodies ; it is only slightly soluble in water, and after being shaken up with that liquid more or less quickly subsides and forms a layer at the bottom. 109. Iodoform, CHI3. — This is a yellow solid body, analogous in con- stitution to chloroform. 110. Organic Acids. — These bodies constitute a numerous class of organic compounds ; like the radicals, they are capable of subdivision into distinct families, the members of which exhibit considerable resemblance to each other. Several of these groups of acids are derivatives from corre- sponding series of alcohols. 111. Fatty Acids, or Acids of Acetic Series. — These acids may be repre- series r C H 1 sented by the general formula,! ’ The lowest member of the is formic acid,|^Qjl^Q or HC2H3O2. Acetic acid is the derivative from ethyl alco- COHO or HCHO2. The next and best known is acetic ORGANIC COMPOUNDS. 49 hoi. It will be of service to place side by side for comparison the formulae of ethyl and some of its principal derivatives : — C2H5HO, or f C0H5 tCA Ethyl. f CH3 \ CH2HO C2ll5^ Ethyl Oxide or Ether. CH3 COH Ethyl Hydroxide or Alcohol. Acetic Aldehyde. CH3 COHO Acetic Acid. By oxidising agents, two atoms of hydrogen may be removed from alcohol with the formation of acetic aldehyde. This body is formed as an inter- mediate step between alcohol and acetic acid. Aldehyde readily combines with another atom of oxygen to form acetic acid. Further reference is made subsequently to the aldehydes as a class. 112. Acetic Acid, — This body is a liquid which boils at a temperature of 117° and freezes at 17° C. ; it has a sharp but pleasant smell, and is well known in a dilute form as. vinegar. Vinegar is manufactured by a species of fermentation from alcohol : its interest in connection with our present subject, lies in the fact that during many fermenting processes acetic acid is produced. 113. Butyric Acid, C3H, COHO, or HC4H„02. — This body bears the same relation to butyl alcohol that acetic acid does to that of ethyl. Butyric acid occurs in rancid butter, sweat, and many animal secretions. It is also one of the products of putrefaction, or putrid fermentation, of many organic substances ; for instance, it may be formed in considerable quantity by the action of putrid cheese on sugar. Butyric acid is a liquid having a sharp odour resembling that of rancid butter. 114. The Higher Fatty Acids. — These have received their special name because of their occurrence as constituents of many natural fats ; among those thus found are butyric acid (above described) ; palmitic j^Q^Q) or HC^j.H 3^02 ; margaric acid, HC^7H3302 ; and stearic f C H acid, I qqjjq’ or HCj8H3.02. These latter bodies are at ordinary tem- peratures fatty solids, melting into oily liquids with an increase of tempera- ture. Physically, they bear little resemblance to acetic acid ; but the formulae at once show their similarity in constitution. 115. Fats and Soaps, or Salts of Higher Fatty Acids. — Most natural fats are salts of the higher fatty acids, with glycerin as the base ; for ex- ample, mutton fat is essentially composed of the stearate of glycerin. This body may be artificially produced by heating together stearic acid and glycerin, according to the following equation — 3HC,8H3.502 + C3H5(H0)3 = C3H5(C,8H350 2) 3 + 3H2O. Stearic Acid. Glycerin. Glycerin Stearate. Water. Some natural fats contain an excess of the fatty acid over and above that sufficient to combine with the whole of the glycerin present. In addition to the “ fatty acids, acids of another group, known as the oleic series, are found as constituents of natural oils and fats. Oleic acid, HC,8H3302, is the product of oxidation of an alcohol of the family C„H2„_,H0 series : it will be noticed that the formula of the acid differs from that of stearic acid by containing two atoms less of hydrogen : this B 50 THE TECHNOLOGY OF BREAD-MAKING. difference follows from the difference in the typical formulae of the two series of alcohols. Tlie oleates of glycerin constitute the oils or liquid portions of fats. By the action of alkalies, as soda or potash, the fats are decomposed, with the formation of sodium or potassium salts of the fatty acids, and the liberation of glycerin in the free state. These salts constitute the bodies known technically as “ soaps,"" those of sodium are the “ hard,"" and those of potassium “ soft "" soaps. The separation of fats into glycerin and the fatty acids may also be effected by forcing a current of steam through the* melted fat. The glycerin distils over with the steam. This operation of decomposing fat by the aid of alkalies is termed “ saponification,"" and, in addition to its great use in the commercial manufacture of soap, constitutes a valuable method of investigating the composition and properties of natural fats and oils. Some few other organic acids of interest yet remain to be described : among these there is : — 116. Lactic Acid, HC3H5O3. — This body occurs in sour mhk, and is also produced in greater or less quantities during fermentation with ordinary commercial yeast. Lactic acid is a sirupy liquid of specific gravity 1*215, colourless and odourless, and having a very sharp sour taste. It forms a well-defined series of salts. 117. Succinic Acid, H 2 C 4 H 4 O 4 . — Succinic acid is a white solid boly, soluble in water. It is one of the bodies produced during the normal alco- holic fermentation of sugar. On being heated, succinic acid evolves dense suffocating fumes. 118. " Tartaric Acid, H 2 C 4 H 4 O 6 . — This body occurs naturally as a con- stituent of the juice of the grape, and in various other plants. It is when pure a white ^olid crystalline body, soluble in water, and possessing a plea- sant sour taste. On being heated, tartaric acid evolves an odour of burnt sugar. Tartaric acid is dibasic, and forms both an acid and a normal series of salts, termed “ tartrates."" The well-known substance “ cream of tartar "" is acid potassium tartrate, KHC^H^Og ; this body has an acid reaction, and, like tartaric acid, decomposes sodium carbonate with the evolution of carbon dioxide gas. As, however, one-half the hydrogen has been al- ready replaced in cream of tartar by potassium, that salt has only half the power, molecule for molecule, of decomposing sodium carbonate that is possessed by free tartaric acid. When acid potassium tartrate is neutralised by the addition of sodium carbonate so long as effervescence occurs, there is produced a double tartrate of potassium and sodium, KNaC^H^Og. This body is soluble in water, and is known as “ Rochelle salt."" 119. Definition of Homologues, ete. — At this stage of the subject it will be convenient to explain the meaning which is attached to “ homo- logue "" and other similar terms used in describing organic bodies. Series of bodies are termed homologous, in which their general constitution maybe repre- sented by a typical formula ; thus, the organic radicals of the methyl series are homologous, so too are the corresponding alcohols, and also the fatty acids. The melting and boiling points of the members of a homologous series usually rise as the series is ascended. When capable of being vapourised, their*density in the gaseous condition increases with the ascent of the series. In many cases, the lower members of a series of homologues are more chemi- cally active than are the higher members. Many organic bodies are known which not only contain the same ele- ments, but also contain them in the same proportion, while their physical ORGANIC COMPOUNDS. 51 and chemical character show them, nevertheless, to be distinct compounds. Distinct compounds, having the same percentage ccmpcsiticn, are said to he “ isomers,"' or “ isomeric with each other.” Isomerism may be of different kinds. Thus, bodies may have the same percentage composition, and yet have different molecular weights : in these cases the molecular weights are multiples of the simplest possible molecular weight that can be deduced from the percentage composition. Bodies having the same percentage com- , position, hut different molecular weights, are said to he “ polymers," cr “ poly- meric ” with each other. The following are instances of polymeric bodies : — Ethylene — C2II4. Propylene — C3H6. Butylene — C4II8. In addition to isomerism of the above type there is yet another more striking variety. When distinct chemical compounds have not only the same percentage composition, hut also the same molecular weight, they are said to he “ metamers,” or “ metameric " with each other. As examples of metameric compounds, the following three bodies may be cited — propylamine, methylethylamine, and trimethylamine. These three bodies all have the formula NC3H9. That they are distinct compounds containing the same proportions of carbon and hydrogen, but united together to form different organic radicals, is seen when the formulae are written as below : — f CsH, rcH 3 N H N C2H5 IH 1h Propylamine. Methylethylamine. f CH3 N CH3 ICH3 Trimethylamine, The nature and constitution of these bodies are described in paragraph 126 . 120. The Aldehydes. — One of the members of this group, acetic alde- hyde, has already been mentioned in a previous paragraph ; as explained, its preparation is effected by the removal of hydrogen from the correspond- ing alcohol. Hence the name aldehyde, derived from “ afcohol dehydvo- genatum." The lowest aldehyde of the ethyl series is that derived from methyl alcohol according to the following equation : — CH3HO = HCOH + H2. Methyl Alcohol. Methyl or Formic Aldehyde (Formaldehyde). Hydrogen. The oxygen of the aldehydes is directly united to the carbon, and is not present as hydroxyl as in the alcohols. This is shown in the comparative graphic formulae given subsequently. Formic aldehyde is a powerful and well-known disinfectant ; its solu- tion in water, termed formalin, is employed both as a disinfectant and preservative. 121. The Aldoses. — Closely allied to the aldehydes are the bodies collec- tively known as aldoses. Among these is hexose, which is an aldose con- taining six atoms of carbon, and having the formula HsCOHAHCOHUOH, or CgHjaOg. There are several hexoses, one of the number being the well- known sugar, glucose. Hexose and the homologous aldoses have for ulae which are multiples of that of formic aldehyde. They all contain the CO group. 122. The Ketones. — A group of substitution compounds is produced by the replacement of the hydrogen of an aldehyde by a radical of the ethyl series ; thus acetone results from the substitution of methyl for hydrogen in acetic aldehyde : — 52 THE TECHNOLOGY OF BREAD-MAKING. CH3COH. CH3COCH3. Aldehyde. Acetone. These bodies are called ketones, the name being derived from acetone. It will be observed that the independent CO group is still present. An important ketone is butyl-methyl ketone, of which the formula is C4HyCO-CH3. 123. The Ketoses. — The ketoses may be regarded as ketones in which the hydrogen of the radical has in part been replaced by hydroxyl. By this replacement butyl-methyl ketone becomes the ketose, fructose or Isevu- lose, of which the formula is CHaOH-CHOH'CHOH-CHOH-CO-CHaOH. Lsevulose is a form of sugar. The relationship of these various bodies to each other is of importance as throwing light on the chemical constitution of the sugars and other allied compounds, to which in subsequent chapters extended reference is made. The following graphic formulae show how these bodies are related to each other. H I H— C— H I 0 H I H— C =0 H Methyl Alcohol. Methyl, or Formic, Aldehyde. H H H 1 H— C— H 1 I H— C— H 1 H— C— H 1 H— C— H 1 1 H— C=0 I H— C— H 1 0 1 I H— C— H 1 H j- H— C=0 Ethyl Alcohol. Acetic Aldehyde. [Butylrddebvdo. H H I H— C— H 1 H— C— 0— H 1 H— C— H 1 H— cLo— F 1 H— C— H 1 H— C— 0— H 1 H— C— H 1 1 H— C— 0— H 1 H— C— H 1 1 H— C— 0— H 1 H— C— H 1 1 H— C=0 1 0 Hexylio Alcohol. Hexose, Glucose. ORGANIC COMPOUNDS. H H 53 H— C— H H— C— 0— H I H— C— H H— C— 0— H I H— C— H I H— C— 0— H 1 H— C— H 1 1 H— C— 0— H 1 1 c=o 1 C-:0 1 H— C— H 1 H— C— 0— H 1 H Butyl-Methyl Ketone, 1 H Lasvulose (Ketose). The relationship between methyl alcohol and its corresponding aldehyde is very simple, one atom of hydrogen and one group of hydroxyl are replaced by an atom of dyad oxygen. The same holds good with regard to ethyl alcohol and acetic aldehyde. An inspection of the formulae shows that while in the alcohol the ethyl radical is intact and is combined with an extraneous group of hydroxyl, in the corresponding aldehyde the oxygen atom has made an inroad into the ethyl group and has replaced one of its atoms of hydrogen. The aldehyde is not that of the intact C,jH2„+i radical, but that of the next higher member of the series. Similarly, butyl is C4H9, but butyl aldehyde is C3H7COH as shown in the graphic formula. Coming next to the hexose as a member of the aldoses, the formula of hexylic alcohol is given beside it in order that the two types may be com- pared. In the case of five of the carbon atoms, an atom of hydrogen has been replaced by hydroxyl, while with the remaining carbon atom the same change has occurred as in the conversion of alcohols into aldehydes. The formation of ketones is rendered clear by the before given formulae of aldehyde and acetone. Turning to the more complicated ketones, the formula of butyl- methyl ketone is given, but the principle of the nomen- clature is not quite the same. Butyl aldehyde is C3H7COH, in accordance with the rule of naming other aldehydes, but that part of the formula of butyl-methyl ketone above the dotted line which is on the pattern of the formula of an aldehyde, in composition reads C4II9CO— , that is to say, the butyl radical is intact with the aldehydic carbon atom added on to it. Fol- lowing the same rule as in aldehydes generally, this would be regarded as the aldehyde of the next higher radical, amyl, CsHn. One must, there- fore, regard these ketones as combinations of the group CO (carbonyl) with the intact radicals from which the name is derived. In the ketoses, a portion of the hydrogen of the ketone is replaced by groups of hydroxyl, and examination of the formulae shows the ketoses to bear much the same relation in composition to the ketones as do the aldoses to the corresponding alcohols. J24. Pentose and Pentosan. — Passing mention must be made of the pentose group of aldoses. These contain five atoms of hydrogen, the formula of pentose being CsH^oOs. By condensation with elimination of water, the pentoses furnish the corresponding pentosans thus : — C5H40O5 = C5H8O4 + H2O. Pentose. Pentosan. Water. These bodies ar e found in the woody fibre of the outer envelope of wheat, and by hydrolysis yield pentose sugars. 54 THE TECHNOLOGY OF BREAD-MAKING. 125. Nitrogenous Organic Bodies.— Many organic compounds, both from animal and vegetable sources, contain nitrogen as one of their con- stituents. The constitution of the majority of these bodies has not as yet been completely investigated ; a large number of them are, however, basic in their character, and hence are known as nitrogenous organic bases, or “ alkaloids.’' 126 Amines, Substitution, or Compound, Ammonias.— Many of the nitroae’nous organic bodies are built upon the same type as ammonia, and may be viewed as ammonia in which one or more of the atoms of hydrogen are replaced by compound radicals. These compounds are termed “ amines,” or “ substitution ammonias.” The three bodies, propylamine, methylethyl- amine and trimethylamine, whose formula are given in a preceding para- graph’ are examples of amines. The methylamines are gases at ordinary temperatures, having a strong ammoniacal and fish-like smell. Trimethyl- amine is produced by decomposing proteins, and is the source of the char- acteristic smell of fish. 127 Alkaloids.— This name is applied to a class of organic bodies, most of which contain nitrogen, carbon, hydrogen, and oxygen. All these bodies are basic while many are able to neutralise even the strongest acids, as sulphuric acid. They are, as a class, remarkably energetic in their action on animals; thus, quinine and morphine are most powerful medicines, while strychnine and brucine are among the most violent poisons; but little is understood of the constitution of the alkaloids ; it is probable that they are of the same type as the compound ammonias. For the sake of uniformity in chemical nomenclature, it has been proposed to restrict the termination “ ine ” to the alkaloids ; for this reason, glycerin, dextrin, etc., should never be written glycerine, dextrine, etc. 128 Amino-acids — ^The amino-acids are bodies intermediate in character between an acid and a weak base, fulfilling under difierent circumstances the functions of either. They have no acid taste, do not redden litmus, and are derivatives from organic acids in which hydrogen of the acid radical is replaced by amidogen. . „ -j Among members of this group are glycine, or amino-acetic acid, C'aHeNOarthe relation of which to acetic acid is shown in the following graphic formulae ; — H H H— C— H 0 =C- 0 -H Acetic Acid. H— C— N -H H 0 =C— 0 — H Amino- Acetic Acid. Aspartic acid, amino-succinic acid, C 4 H 7 N 04 , and glutamic acid, amino- glutaric acid, C 5 H 9 NO 4 , are members of this group. So also are leucine, amino-caproic acid, CeH.aNOa, and tyrosine, amino-oxy-phenyl-propionic acid, C9H44NO3. All these bodies are important constituents and decom- position products of the proteins. Leucine is soluble at 12 C. in 48 parts of water and 800 of alcohol ; and insoluble in ether Tyrosine dissolves in 150 parts of boiling water, and is insoluble in alcohol and ether. 129 Amides —Amides maybe regarded as derivatives of acids in which amidogen, NH^ replaces hydroxyl, HO; or they may be looked on as ammonia in which one or more of the hydrogen atoms are replaced by organic radicals. Urea, CON3H4, is a typical amide. It may be viewed L a derivative of carbonic acid, CO(HO)3, in which case the two groups of ORGANIC COMPOUNDS. 55 HO are replaced by two groups of NH2 ; or on the other hypothesis may be regarded as two molecules of ammonia, NH3, with a pair of hydrogen atoms replaced by CO, thus /H \N— C— N^ li 0 = CON2H4 Urea, Carbamide. The amides are distinguished from the amines by the latter being incap- able of derivation in constitution from an acid. Among amides found in plants are asparagine, C4H8N2O3, and glutamine, C5H10N2O3. Asparagine is the amide of amino-succinic acid. The relation between succinic acid, amino-succinic acid, and the amide asparagine is shown in the following formulae : — 0 =C— 0 — H I H— C— H H— C— H 0 =C— 0 — H Succinic Acid. 0 :=C— 0 — H I JJ H— c— N c:" I H— C— H I 0 =C— 0 — H Amino-Succinic Acid. 0 =C— 0 — H I TJ H-C-NCS H— C— H I H 0 =C-N Ch Asparagine (Amide). The amides are crystalline, diffusible bodies. Asparagine is soluble in hot water, but not in alcohol or ether. 130. Phenylhydrazine. — ^Among the compounds of nitrogen with hydro- gen is that known as hydrazine, N2H4. Further, there is a compound of hydrogen and carbon named benzene, CsHe. This body is regarded as a combination of a radical, phenyl, CeHs, with hydrogen. The generally accepted view of the composition of the bodies of this group is that sug- gested by Kekule, who regarded the carbon atoms as forming a closed chain, as shown in the following formula : — H H C H \ c c c c / X/'\ H C H I H Benzene or Phenylliydride. If one of the atoms of hydrogen in hydrazine be replaced by phenyl, CeHs, phenylhydrazine is produced, and has the formula, C6H5NHNH2. This body is of importance because of the great value it has been in the investigation of the composition of the sugars. 131. Phenylhydrazones or Hydrazones. — ^Phenylhydrazine is eapable of entering into combination with aldehydes, aldoses, ketones and ketoses, in the proportions of one molecule of each with the elimination of a molecule of water. The bodies thus produced are termed phenylhydrazones, or more briefly, hydrazones. The formation of two of these bodies is shown in the following equations : — 56 THE TECHNOLOGY OF BREAD-MAKING. CH3COH -f N2H3C6H5 = CH3CN2H2C6H5 -f H2O. Aldehyde. Phenylhydrazine. Aldehyde-hydrazone. Water. H2C0H(HC0H)4C0H+N2H3C6H5=H2C0H(HC0H)4CN2H2C6H5+H20. Hexose, Glucose. Phenylliydrazine. Glucose-hydrazone. Water. The hydrazones occasionally serve as means of identifying sugars, but are far exceeded in value for that purpose by the compounds described in the next paragraph. 132. Phenylosazones or Osazones. — ^When an aqueous solution of either an aldose or ketose is heated together with phenylhydrazine acetate in the proportion of one molecule of the former to three molecules of the acetate, a somewhat complicated reaction ensues. Among its products is a compound consisting of two molecules of phenylhydrazine with one of the aldose or ketose, which body is a phenylosazone, or more shortly osazone. Taking the example of glucose, the following is the formula of the phenyl- glucosazone : — H2C0H(HC0H)3CN2HC6H5CN2H2C6H5. ( Phenylglucosazone. Two groups of phenylhydrazine have become incorporated in the mole- cule of glucose with the elimination of two molecules of water. There are other secondary chemical changes which need not be further described. The osazones have well marked chemical characteristics in the direction of opticity and other properties. These are of great service in identifying particular sugars, the modus operandi being to prepare the osazone, and then through the properties of this body to identify the sugar. CHAPTER IV. THE MICROSCOPE, AND POLARISATION OF LIGHT. 133. Object of Microscope. — description of the microscope, and method of using it, is given at this early stage, because the student will continually find it requisite to have recourse to this instrument from time to time, while going on with his study of the chemical properties of the various grain constituents. In order to thoroughly understand the physical construc- tion of bodies it is necessary to see them. The microscope is an instru- ment to enable us to see points of physical construction which are so minute as to escape the unaided vision. 134. Description of Microscope. — ^The demand for good microscopes has led to the supply by a number of makers, both English and Continental, of really excellent instruments at low cost. In consequence, the microscope is not now, even to the general public, an unfamiliar piece of apparatus. These pages are not the place where an exhaustive description of micro- scopes could with fitness be given, but as the instrument should be in the hands of every miller and baker, a few hints as to how to use it for such purposes as those occurring during milling and bread-making will naturally find a place in this work. As an instrument suitable for the work of miller and baker, the authors have figured one supplied by Charles Baker, of 244, High Holborn, London. These microscopes are cheap (in the best sense of the term), of excellent make, and always trustworthy. Every reader will probably be familiar with the general appearance of the instrument as shown in the illustration. The microscope proper consists of the stand, to which is attached the main tube of the instrument, by means of a sliding “ dove- tail '' arrangement, that can be raised or lowered by a rack and pinion : the pair of milled heads, d, actuate this pinion. Below is another pair of milled heads, E, which are more delicate in their action, and constitute what is known as the “fine adjustment.” The stage, G, is that part of the instrument arranged for the reception of the objeet being examined. It consists of a flat surface at right angles to the axis through the tube of the microscope, and carries on it a pair of spring clips, f, by means of which the glass on which the object is mounted is held on the stage, g, and thus may be shifted in any direction by the fingers. Underneath the stage is a contrivanee known technically as the sub-stage, h : this is also fitted with a rack and pinion, and may be raised or lowered by the milled head, i. The central aperture of the sub- stage is arranged to take either a sub-stage illuminator (Abbe condenser), a series of diaphragms, the polariser of a polarising apparatus, or other desired sub-stage fittings. Beneath this again is a concave glass mirror, J, so mounted as to be easily placed in any required position. The tube of the miroscope, together with the stage and mirror, can be turned at any angle to the tripod stand, from the vertical to the horizontal. Within the main tube is fitted a second, b, known as the “draw tube,” which can be pulled out if required, thus inereasing the distance between the eye-piece and object glass. A scale is engraved on the side of the draw tube, by which 57 58 THE TECHNOLOGY OF BREAD-MAKING. the amount of withdrawal can be observed and noted. The lower end of the main tube is provided with an internal screw at c, for the purpose of receiving the combinations of lenses known as “ object glasses/" or “ objec- tives."" The objectives of all the best makers are now cut with the same screw thread, and so are interchangeable. The “ eye-piece/" a, also a lens combination, slides into the top of the draw tube. The objectives are named according to their focal length, and are consequently termed “ 1-in. objec- Fig. 2. — The Microscope. fives,"" etc. One of these is shown in position at L. The greater the focal length, the less is the magnifying power of an objective. The eye-pieces also vary in magnifying power, and are usually referred to as “A,"" “ B "" eye-pieces, and so on ; the magnification increases with each successive THE MICROSCOPE. 59 letter of the alphabet, commencing with A. The student will require a series of objectives, consisting of the 2-inch, 1-inch, and J-inch ; these will be found to answer most purposes, although for bacteriological work a yV-inch oil immersion objective in addition is exceedingly useful. In working with a microscope it is frequently necessary to change from a high to a low magnifying power. In order to do this rapidly, microscopes are now pro- vided with a carrier, k, which screws into the tube at c, and to which a number of objectives, L, l1, l2, is attached. By rotating this carrier the various objectives may be quickly exchanged for each other. In the follow- ing description it will be assumed that the instrument is fitted with such a carrier. For ordinary work the A eye-piece is sufficient, but a C eye-piece is also at times useful. The following accessories are requisite : one or two dozen glass slides, 3 inches by 1 ; some thin glass covers — these may be round or square, and should be about f inch diameter, or square ; a pair of fine forceps ; one or two needles set in handles ; a glass rod drawn out to a point at one end, and a small piece of glass tubing. All these may be obtained from the maker of the microscope, and are usually supplied in the case with the instrument. Other useful pieces of additional apparatus will be mentioned as necessity arises for their employment. A word may be said in the first place about the preserving of the instru ment from injury. When not in use it should either be kept in its case, or, what is more convenient, under a glass shade, as then it can be readily used when required. A mounted longitudinal section of a grain of wheat should be purchased at the same time as the instrument ; this is a very useful slide to possess, and will give the student an opportunity of learning how to use his microscope before he proceeds to mounting objects for himself. 135. How to Use the Microscope. — ^To commence using the instrument, remove it from the case, take the 2-inch objective out of its box and screw it into the bottom of the tube ; next insert the eye-piece in its place. The lenses, if dusty, may be very gently wiped with either an old silk handker- chief that has been often washed, or a piece of wash-leather. One or other of these should be kept solely for this purpose. The less, however, that the lenses require wiping the better, as, being made of soft glass, they easily scratch. When working on yeast, temporarily mounted in water or other liquid substance, it is necessary to set the stage horizontal, as otherwise the liquid flows downward. But with fixed and permanent objects, the microscope should be inclined to an angle of about 45 degrees, as in such a position the eye is much less fatigued during observation. The next requisite is light. In the daytime choose a room that is well lighted, if possible not by direct sunlight, but by a bright cloud. At night an incandescent gas burner, especially if enclosed in a ground glass globe, makes a good source of light. Raise the microscope tube by turning the pinion, by means of the milled head, d, until the end of the objective is about 2 inches from the stage. Place the mounted wheat grain slide on the stage, and arrange the clips to hold it firmly. Next turn the mirror so as to throw the spot of light on the object. Now look down the eye-piece and lower the microscope tube until the object is focussed ; that is, until its outlines are seen clearly with- out being blurred. A word may here be said about the amount of light advisable ; generally speaking, the rule may be laid down that it is wise to work with no more light than necessary. The light should not be bright enough to dazzle the eye in the slightest degree ; on the other hand, it should be sufficient for the object to be seen comfortably. The 2-inch objec- tive will show the greater portion of the grain of wheat occupying the whole of the field of vision. Any object when seen through the microscope is 60 THE TECHNOLOGY OF BREAD-MAKING. inverted ; that is, the top is seen at the bottom, and the left side at the right. By pulling out the draw tube the object is still further magnified. In the next place rotate the carrier so as to substitute the 1-inch for the 2-inch objective. The microscope tube will now have to be lowered until the object is again in focus. A smaller portion only of the wheat-grain is seen in the field, but that portion is magnified to a much greater degree. The illumination is much less than with the 2-inch object glass. Notice that more of the details of the object can be distinguished. The J-inch objective may now be tried. Unless the section is a very thin one, it will not, however, show up well. Having exchanged the inch for this power, lower the microscope tube until the end of the object glass is within an eighth of an inch from the slide ; then move the milled head D, very slowly and carefully, watching all the time until the object is again in focus : for this purpose it is well to move the slide until a portion of the skin of the grain is in view. The milled head, e, may now be used for mak- ing the final adjustment of the focus. This latter milled head is termed tlie “ fine adjustment,"’ while that by means of the rack and pinion is spoken of as the “ coarse adjustment.” For the lower powers the coarse adjust- ment is sufficient. This exercise with the three powers will have shown the student the mode of using his microscope. He must accustom himself to moving the object about on the stage, so as to get any portion he wishes in view ; this presents some little difficulty at first, because the movement must be made in the opposite direction to that in which it is desired that the magnified image shall travel. Any”; experimenting with the oil or water immersion objective had better be postponed until the student arrives at the stage of examining bacteriological specimens. 136. Measurement of Microscopic Objects. — The microscope is not merely used for the purpose of seeing small objects, but, with the addition of certain accessories, is also employed for measuring their size. The first object requisite for this purpose is a “ stage micrometer ” ; an eye-piece micrometer should also be procured. The stage micrometer may consist of a fraction of an inch further divided up into tenths and hundredths, or preferably of a millimetre similarly graduated. The scale for this purpose is accurately photographed on a glass slip, the same as an ordinary slide. It will be remembered that the millimetre is very nearly the twenty-fifth part of an inch, consequently the tenth or hundredth of a millimetre may be taken as equal to the two hundred and fiftieth, or two thousand five hundredth part of an inch. Work- ing with low powers, it is sufficient for rough purposes to place the stage micrometer face down- Avards on the object to be measured, and then to read the number of divisions of the micrometer over which the object to be measured extends. This can only be done with powers sufficiently low to permit the lines on the micrometer, and the object under examination, to be in focus, or nearly so, at the same time. The eye-piece micrometer is, for all purposes, far preferable. - This instru- ment consists of a scale engraved on a circular piece of glass, as shown in Fig. 3, which is Fig. 3. Eye-Piece Micrometer. THE MICROSCOPE. 61 fixed in a specially adapted eye-piece, also figured. The top of the eye- piece draws out, and the micrometer scale is dropped in, so as to rest on the diaphragm shown in section midway of the eye-piece. The figures, of course, must be uppermost, so as to read rightly on looking down the micro- scope. The scale being in position, the sliding tube of the eye-piece itself is drawn up or down until, on looking through it, the graduations are sharply focussed. With the eye-piece in position, on looking down the microscope, both the eye-piece scale and the object are seen in focus together. The scale looks as though it were simply superposed on the object. The value of this scale varies with each different power employed, but may be deter- mined in the following manner — place the lowest power into position on the microscope ; put the stage micrometer on the stage, and read off care- fully in tenths and hundredths of a millimetre the value of one division of the eye-piece micrometer. Next repeat the same measurement in exactly the same way with each of the other objectives. In these determinations the draw tube must invariably be in the same position ; it is best to have it always closed when the microscope is being used for measuring purposes. Thus, for example, with one of the microscopes in the possession of the authors one division of the eye-piece has the following values wdth different objectives : — Objective. M.m. M.k.m. Inch. AA, Zeiss . . 0-0286 . . 28-6 . . 0-00126 A ., 0-01734 . . 17-34 . . 0-00068 DD, ,, 0-004098 4-098 . . 0-00016 One-twelfth oil immersion . . 0-001265 1-265 . . 0-00005 One-twentieth ,, ,, 0-001087 1-087 . . 0-000043 Supposing that an object, under examination with the highest power, on being measured is 3*2 eye-piece divisions in length, then its real length is 0-001087 X 3-2 = 0-00348 m.m., or 0-000137 inch. 137. The Micromillimetre. — ^When the dimensions of minute objects are expressed either in inches or in millimetres they require such a number of figures that it is difficult to at first realise the value of the dimension. It has therefore been proposed to employ the one-thousandth part of a milli metre as a unit of length for microscopic measurements. This unit is called a micromillimetre, for which the following abbreviation, “ mkm.,'" may be used. The mkm. is also sometimes called a “ /x ” pronounced mu ) ; its value in inches is very nearly 2 Tii o o inch. The eye-piece measurements given in the preceding paragraph have also their values expressed in micro- milhmetres. 138. Magnification in Diameters. — ^There remains to be explained a convenient method of measuring the magnifying power of objectives and eye-pieces. A common method of expressing the value of particular com- binations of these two is to say that they magnify so many diameters. A moment's reflection will show that the image seen with a microscope will vary in actual dimensions, according to whether it be supposed to be near to or far from the eye. The only real measurement, in fact, is the visual angle it subtends. This being the case, the measurement in diameters is always expressed with the understanding that the object is supposed to be ten inches from the eye. Here for a moment a slight digression must be made. Most beginners when looking through a microscope close the eye not in use. This is a bad plan, as the eyes are thereby much more fatigued. Both eyes should be kept open. At first the surrounding objects are continually being seen 62 THE TECHNOLOGY OF BREAD-MAKING. with the unoccupied eye, and it is apparently a hopeless case to see the object under the microscope at all. Practice overcomes this, but the authors have found the best plan is to fix to the microscope tube a piece of dead black cardboard, so that the unoccupied eye sees only a black surface. The object will now be observed with the greatest readiness, and probably not one quarter the fatigue. In a very short time the cardboard shield may be dispensed with, and the trained eyes so behave that the one is transmitting the view of the microscopic object to the brain, while the other is remaining idle and resting. The student should accustom himself to use either eye indifferently ; he will soon find that he will no more think of closing one eye when looking through his microscope than he would of tying his left hand behind his back before he shakes hands with his right. Now, the object of our momentary departure will be evident ; the idle eye can, at will, be used for looking at something else, so that the one eye is looking at the microscopic object, the other, if wished, at say a piece of paper. Place the stage micrometer in focus, and fix a piece of stiff paper or cardboard as near as possible to the microscope, at right angles to its axis, and ten inches from the eye-piece. Look down the tube with the one eye, and with the other at the piece of paper. The magnified micrometer scale appears as though drawn on the paper. Still using both eyes, trace with a pencil on the paper the exact position of each line representing the tenths or hundredths of the millimetre. Next measure on the paper the distance between the two marks traced from, say, the tenths of a millimetre ; suppose that this distance is five millimetres, then that particular combina- tion of eye-piece and objective has a magnifying power of fifty diameters. Measure each other combination possible with the various eye-pieces and objectives in your possession in the same way. 139. Microscopic Sketching and Tracing. — ^The above method of measur- ing is very useful, because with small objects occupying a portion only of the field, it is possible to trace them on the paper in the manner described, and such tracings are then known to be magnified to the extent ascertained by previous measurement as directed. Such sketching by actual tracing is very desirable in microscopic work, as otherwise the student is extremely likely to draw an object either too large or too small ; this is to be avoided, as one object of microscopic examination is to definitely ascertain the size of objects. It is the authors' practice when working without sketching to note the measurements with the eye-piece micrometer. When sketching they make tracings of sufficient at least of the object to give its actual dimensions, by a process similar in principle to that already described. 140. Camera Lucida. — ^For tracing with the microscope an appliance has been invented, which is known as a ‘‘ camera lucida " ; there is also a modification termed a neutral tint camera. An ingenious combination of eye-piece and camera lucida in one piece of apparatus is shown in section in Fig. 4. The principal portion of the figure consists of the ordinary eye- piece, a, h, with its upper and lower lenses, c, d ; the central dotted line, e, /, is the direct axis of vision through the microscope. At the top right hand of the figure is a glass prism, g, of peculiar shape. The angles of this are so arranged that a ray of light, passing in the direction h, i, is totally reflected at i, in the direction ^, k, and again at k is totally reflected in the line k, 1. The^result is that the eye placed over the aperture of the eye-piece, at m, re- ceives both rays of light, /, e, and h, i, k, I, which enter the eye parallel to each other. In consequence, the eye sees simultaneously with the object under the microscope any other object placed in the direction of the line 1i ; both are combined and appear to be in the direct line of THE MICROSCOPE. 63 vision througli the instrument. Consequently if a sheet of paper be placed under i, h, it and the microscope image appear to the eye to coincide. When wishing to use the camera, place the microscope in a vertical position, directly facing the source of light, and turn the camera so that the prism, g, is at the right-hand side (as figured). Procure a box or other convenient stand of such a height that its upper surface, when placed beside the microscope, is of the same height as the microscope stage. Place this box on the right-hand side of the instrument, under the prism, g, so that the line, ^, h, points to it. For drawing purposes the most convenient arrangement is a small draw- ing “ block "" of hot pressed paper, sheet after sheet of which can be removed as fin- ished. Place this on the stand, under ^, h, and look through the instrument ; both object and paper should be seen in com- bination ; that is, the image should appear to be superposed on the paper. To pro- perly get this effect the paper and image should, as nearly as possible, be equally illuminated. As the paper is usually brighter than the image, provision is made for cutting off some of the light from it by introducing plates of neutrah tinted glass in the path of ^, just below the prism g. On the other hand, the illumination of the object may be adjusted by means of the reflecting mirror of the microscope. As a preliminary to tracing with the camera, place the stage micro- meter in focus, and the microscope and paper in ’their respective positions. Then, by means of a pencil, mark on the paper the length of the millimetre or fraction of the millimetre, and calculate out once for all the magnification in exact "number of diameters. This is very easily done, as the lines of the object appear to be drawn on the paper ; the pencil point being also seen, the operation of tracing simply consists of going over lines apparently already on the paper. With the same powers and eye-pieces, and microscope and paper in the same relative positions, the magnification is always the same. In actual sketching it is usually sufficient to trace in the principal outlines ; the details may then be added with sufficient accuracy by the ordinary method of judging dimensions by the eye, as in freehand drawing. Fig. 4. — Combination of Eye Piece and Camera Lucida. 141. Microscopic Counting : the Haematimeter. — ^For certain purposes it is highly important to be able to count the number^of small solid particles suspended in a fluid. Among them is the counting of blood corpuscles, and of yeast cells suspended in water or fermenting liquid. An instrument was first devised for this purpose, in order to count blood corpuscles, and hence is called a haematimeter ; the same appliance is adapted to the •counting of yeast cells, and is illustrated in Fig. 5. The instrument consists of a stout glass slide, on which is cemented a cover-glass with a circular opening, thus constituting a cell. On the glass slide, and in the centre of this cell, is arranged a raised circle of glass, on which is engraved a series of lines at right angles to each other, thus marking its surface off into a number of squares. A representation of this part of the apparatus is given 64 THE TECHNOLOGY OF BREAD-MAKING. on the left of the figure, showing its appearance when viewed through the microscope. Each of the larger squares has an area of 4 ^^ (0-0025) square millimetre. The inner circle of glass, and the outer glass, are so arranged that the former is exactly m.m. the thinner ; so that when the cover- r-l /- r i- d 7 V — -1 7 - Fig. 5. — The H^matimetee. glass is brought down into absolute contact with the outer glass, the space between the lower surface of one and the upper of the other is exactly 0-1 m.m. in thickness. Therefore the cubic contents of the space above each square on the inner glass is 0-0025 X 0-1 = 0-00025 = cubic m.m. To perform a counting operation on yeast, for example, an average sample must be taken, diluted, and shaken up until the cells are uniformly distributed through the liquid. Hansen considers that the liquid most suitable for this purpose is dilute sulphuric acid, 1 part to 10 of water r for yeast the authors prefer to employ 1 part sulphuric acid, 1 part glycerin, and 8 of water. The viscid nature of the glycerin enables the liquid to keep the cells uniformly suspended through it for a longer time. The method of employing the hsematimeter is best explained by giving an actual example. From a sample of compressed yeast, 0*25 grams were weighed off and made up to 50 c.c. with dilute glycerin and sulphuric acid. The yeast was broken down and thoroughly mixed with the liquid by violent shaking for some time in a flask. A droplet was then removed by means of a pointed glass rod, and placed on the centre of the glass of the haematimeter, and immediately covered with the cover : this is held in close contact either by a pair of small spring clips or by a weight put on. (The minute drop for this purpose must not be more than sufficient to- nearly fill the space between the two glass surfaces : it must not be enough to run over into the outside annular space. The apparatus is placed aside in a horizontal position to rest sufficiently long for the suspended cells to fall to tlie bottom of the layer of liquid. The yeast cells having settled down, say in ten minutes, place the haematimeter on the horizontal stage of the microscope , and prepare to commence counting, using about /j-incli objective (Zeiss D). The yeasb cells will be seen lying on the engraved squares, some within the squares, and others directly on the dividing lines. Commence counting the cells within the top left-hand square, and make a note of the number, then go on along the line, come back, and count those on the squares of the next line, and so on. The cells lying on the lines must also, of course, be counted, but only once ; that is, all THE MICROSCOPE. 65 lying on the horizontal lines must be counted in the squares above them and all on vertical lines in the squares to the right of them. The counting must be continued until a sufficient number of squares have been taken to give a true average. By experiment it should be ascertained how many squares must be counted in order that an additional number has no influence on the average obtained. It is usually sufficient to count some 50 or 60 of the squares. It is convenient to have the liquid of such a degree of dilution that about 8-10 cells occur in each square. Approximately the accidental errors amount — by counting £000 cells, to 5 per cent, of the total result. „ 1250 „ 2 ,, 5000 ,5 1 5j >) jj In the experiment being described, 100 squares were counted and contained 738 yeast cells. Now the space above each square = 0-00025 cubic mm. Therefore 100 spaces = 0'025 cubic m.m., and contain 738 cells. Therefore 4000 spaces = POOO cubic m.m., and contain 7 '38 X 4000 = 29,520 cells. Therefore 1 c.c. = 1000 cubic m.m., and contains 29,520 X 1000 = 29,520,000 cells. But 1 c.c. contained 0*005 gram of yeast, and therefore 1 gram contains 29,520,000 X 200 = 5,904,000,000 cells. But 1 lb. avoirdupois = 453*59 grams, and therefore 1 lb. of the yeast contained : — • 5,904,000,000 X 453*59 = 2,677,995,360,000 cells. The smaller grained starches may also be counted in the same manner. 142. — The methods of using the microscope having been briefly described, directions for its use for special purposes will be given as occasion arises. For fuller descriptions of the instrument itself, its accessories and the method of using them, the student is referred to one of the many excellent works already published on the subject. 143. Polarisation of Light. — ^There are many substances which exert a special action on “ polarised light” ; among these are a variety of crystalline compounds, and certain organic bodies. It will be necessary at this stage to give a short description of the nature of a ray of light, and the way in which its character may be altered by the action of these substances just mentioned. As is well known, light travels in straight lines called rays. The actual motion of such a ray of light is somewhat like to that of a sea- wave, or the ripples produced on the smooth surface of a pond by throwing a stone therein. In waves, the water itself does not move forward, but only the undulating motion of the surface ; this is readily seen by floating a cork on the water ; each little wave in its passage onward simply raises and depresses the cork, but leaves it in the same position as it found it. Light, then, also travels in waves, these waves being undulations in a sub- stance filling all space, and known by the name of “ ether."' The waves of light differ remarkably in one particular frorh those on the surface of water ; the undulatory motion in the latter is simply up and down, or, to use the scientific term, in a vertical plane. If the actual movements of the ether in a ray of light could only be rendered visible, a much more complicated motion would be perceived. Just as in the case of the water wave, the particles would move across, or transversely to, the direction of the path of the ray. Some of the particles would rise and fall like those in the water wave, but others would swing from side to side, or horizontally instead of vertically ; further than this, others again would vibrate at every inter- 66 THE TECHNOLOGY OF BREAD-MAKING. mediate angle. This condition of things is expressed in the statement that the undulations of a wave of light are in a plane transverse to the path of the ray, and that the ether particles vibrate in every direction in that plane. For our present purpose it will be sufficient to regard the wave of light as composed of two sets of vibrations, the one vertical, and the other hori- zontal, and therefore at right angles to each other ; the intermediate vibra- tions may be ignored. The character of the undulations of a wave of hght is not greatly altered by passing through glass, water, and many other bodies ; the same does not, however, hold good with all transparent sub- stances — of these one of the most striking is a mineral named tourmaline. Let two thin plates be cut from a crystal of this substance in a certain direc- tion ; on examination each is seen to be fairly transparent. Let one be placed over the other, and then slowly twisted round. In one particular position light passes through them both as readily as through either taken singly ; but as one of the pair is turned round, less and less light is trans- mitted ; until, when it has been rotated through an angle of 90 degrees, no light whatever passes. As the revolution is continued, the plates allow iinore and more light to pass ; until, when an angle of 180 degrees has been reached, the combination of two plates is again transparent. A further revolution of 90 degrees once more causes opacity. This peculiar effect is due to the fact that tourmaline plates, such as described, permit the passage through them of only the vibrations of light in one plane, so that the ray of light, after passing through the tourmaline, instead of having its vibra- tions in all directions of the plane, has them occurring in one direction only ; the ray may then be compared to a water wave. Such a ray of light is said to be “ polar- ised,"' and the change effected is termed the “ polarisation of light."’ The tourmaline plate may be compared to a sieve composed of a set of wires in but one direction. Using this similitude, only those vibrations which are in the same direction as the wires of the sieve succeed in effecting a passage. The second tourmaline plate being set so that its wires are parallel to those of the first, the light which passed through the one succeeds £ilso in passing through the other. But when the second tourmaline is turned at right angles to the first, then the light which passed through the (One is cut off by the other, and so the two together refuse to transmit any light whatever. Persons who are acquainted with the beautiful mineral known as Iceland spar, know that when a single dot is looked at through a piece of the spar, it is seen double ; this is due to the fact that the spar splits the ray of light into two distinct rays ; further, the light of each of these sub-rays is polar- ised in such a manner that the plane of polarisation (that is, the direction Fig. 6. — Nicol’s Prism. in which the vibrations occur) of the one ray is at right angles to that of the other. When pieces of Iceland spar are cut and re-joined in a particular manner, as shown by the oblique line in Fig. 6, they transmit the one only of these two rays, the other being lost by internal refiection within the crystal. Such pieces of spar are termed “ NicoFs prisms," and may be used for the same purpose as .the tourmaline plates ; they have the great advan- tage of being composed of material as transparent as glass, while the tourma- line is usually only semi-transparent, apart from its polarising properties. THE MICROSCOPE. 67 The first NicoPs prism placed in the path of a ray of light is termed the polariser, because it effects the polarisation ; the second is known as the analyser, because it enables us to determine the direction of the plane of the polarised ray. The attachments for a NicoPs prism are shown in Fig. 7, which is an illustration of the polariser and analyser of a microscope. Tlie polariser, in use, is fitted to the sub-stage, and the analyser to the eye-piece, Fig. 7. — Polariser and Analyser of Microscope. Returning again to the similitude of the sieves, suppose that, with the two at right angles to each other, it were possible to take the light after it had passed through the one, and was thus polarised, and twist or rotate its plane of polarisation through an angle of 90° before it came to the second, it would evidently then be able to pass through that also. Certain substances possess this remarkable property : among those of immediate interest in connection with the present subject are starch, sugar, and other of the carbo- hydrates. It is further found that while some compounds twist the polar- ised ray to the right, or in the direction of the hands of a watch, others rotate polarised light to the left. If two NicoPs prisms were so arranged as to give absolute darkness, and then a plate of sugar were placed between them, light would be transmitted. If the analyser were next turned around in a right-handed direction, the point of absolute darkness would again be reached, and then by measuring the angle of rotation, the number of degrees through which the plane of polarisation of light had been rotated by the sugar could be ascertained. Instruments are constructed for the purpose of making this measurement with great delicacy, and are termed “ polarimeters.'' The exact point at which maximum light and darkness is reached during the rotation of the analyser cannot be observed with great accuracy ; recourse is therefore had to observing some of the other char- acteristics of polarised light more easily detected by the eye. In the analytic section of this work, an explanation is given of the principles which guide chemists in the application of the rotation of the plane of the polarisation of light by sugar and other bodies to their estimation ; a practical description then follows of one of the best forms of polarimeter and the method of using it. For microscopic purposes a polariser is fitted underneath the stage, and an analyser either within the body of the tube or over the eye-piece. The object under examination is thus illuminated by polarised light. For further information on the polarisation of light, the student is referred to GanoFs, or some other standard work on physics. CHAPTER V. CONSTITUENTS OF WHEAT AND FLOUR. MINERAL AND FATTY MATTERS. 144. Construction of Wheat Grain.— Having giving a brief outline of the principles and theory of Chemistry, in so far as they are more or less connected with the present subject, our next object must be to describe the chemical properties of the different compounds found in the grain, and to trace them out in the history of the flour and offal. The cereals, to which wheat belongs, is the name given to the grasses which have been cul- tivated for use as food. The grain, as is of course well known, is the seed of the plant ; although not strictly chemical information, it will be well to give here a short description of its various parts. The most important portion of the seed is the embryo or germ ; this, which is a body rich in fatty matters, is that part of the seed which grows into the future plant. The interior of the seed contains a q^uantity of starch and other compounds, designed for the nutrition of the young plant during its earliest stages of growth. The whole is enclosed in an envelope, made up principally of woody fibre, and arranged in a series of coats, one outside the other, some- what like those of an onion, only on a much finer scale. During the process of milling, the grain is divided into flour and what is technically knovn as offal. This latter substance, or group of substances, includes the germ, bran, pollard, etc. The bran and pollard are the different skins of the grain broken up into fragments of various sizes. This department of the subject will be dealt with fully in a subsequent part of the work. 145. Constituents of Wheat.— A large number of chemical compounds may be obtained from grain ; these naturally divide themselves into Mineral or Inorganic Constituents, and Organic Constituents. The inorganic por- tions of wheat consist of water and the mineral bodies found in the ash. Tlie organic compounds may be conveniently grouped into— fatty matters, starch, and allied bodies having a similar chemical composition, and nitro- genous bodies or proteins. Of these substances the fats have the simplest composition, next come the starchy bodies, and lastly, the proteins, whose constitution is extremely complex. 146. Mineral Constituents.— The properties of water are already suffi- ciently described ; the actual amount present in grain varies from about 10 to 15 per cent. In sound wlieats and flours there is no perceptible damp- ness, the water being chemically combined with the starch, which body probably exists in grain as a hydroxide. The other mineral constituents are usually obtained by heating the powdered grain to faint redness in a current (>f air ; the organic bodies burn away and leave an ash consisting of the MINERAL AND FATTY MATTERS. 69 inorganic substances present. The ash of wheat has been made the subject of prolonged investigations and researcli, conducted principally, however, from an agricultural point of view. Land being impoverished by the growth of crops, the constitution of the ash of wheaten grain and straw is an indica- tion of what mineral matters are removed from the soil by wheat crops, and therefore also affords information as to what additions have to be made to an exhausted soil in order to replenish its necessary mineral components. Lawes and Gilbert have from time to time published elaborate tables of results obtained on their experimental farm at Rothampsted ; the following table is abstracted from a communication of theirs to the Chemical Society {Chem. Soc. Jour., vol. xlv., page 305 et seq.). It gives the composition of the grain-ash of wheat, grown on the same land, in four characteristic sea- sons — 1852, 1856, 1858, and 1863 ; the land being treated with farmyard manure : — Harvests — 1852. 1856. 1858. 1863. Weight per bushel of grain, lb. . . . 58-2 58-6 62-6 63-1 Percentage Composition of Ash. I Iron Oxide, Fe 203 0-95 0-86 0-90 0-43 Lime, CaO . . 2-79 I 2-53 2-61 2-34 Magnesia, MgO 12-77 11-71 11-17 11-41 Potash, K 2 O 27-22 j 29-27 31-87 31-54 Soda, Na 25 0-45 0-42 0-28 0-66 Phosphoric Anhydride, P 2 O 5 54-69 54-18 51-88 52-04 Sulphuric Anhydride, SO 3 0-14 0-23 0-75 0-93 Chlorine, CI 2 trace 0-07 0-06 trace Silica, Si 02 . . 0-99 0-75 0-49 0-65 Total 100-00 100-02 100-01 100-00 The ash constitutes about 1 *5 per cent, of wheat, and about 0 4 per cent, of the finished flour, while bran yields from 5 to 7 per cent, of ash. It will be noticed that more than half the wheat ash consists of anhydrous phosphoric acid ; this is principally in combination with potash, forming potassium phosphate. The magnesia is also present as a salt of phosphoric acid. The greater part of wheat ash, therefore, consists of potassium phosphate, and is soluble in water. 147. Composition of the Ash of a Wheat and its Mill Products, Teller.— The following series of ash analyses was made for the purpose of obtaining some further information concerning the distribution of various ash ingre- dients in the wheat grain and in the different products of modern flouring mills. The figures given in the table indicate in per cent, of total ash, the amount of each constituent named. 70 THE TECHNOLOGY OF BREAD-MAKING. Constituents. Patent Plour. straight Flour. Low Grade. Dust Room. Ship Stuff. Bran. Wlieat. Silica . . 2-33 1-28 0-50 1-34 0-49 0-97 ' 1-04 xHumina 0-41 0-15 0-12 0-04 0-18 0-07 0-11 Ferric Oxide. . 0-47 0-26 0-25 i 0-30 0-37 0-27 0-27 Potash 38-50 36-31 32-27 30-85 , 28-03 28-19 29-70 Soda . . 0-00 0-00 0-00 0-00 0-00 0-00 0-00 Lime . . 5-59 ! 5-65 4-51 3-53 2-80 2-50 3-10 Magnesia 4-39 6-44 9-33 12-90 13-27 14-76 13-23 Phosphoric Acid 48-05 49-32 53-10 49-94 54-62 52-81 52.14 Sulphur Trioxide 0-16 0-52 0-00 0-58 0-00 0-10 0-22 Chlorine i — — - — • — 0-01 0-01 Zinc Oxide . . 1 0-04 — 0-46 0-36 0-27 0-24 Total 99-90 99-97 1— 1 o o 6 00 99-94 100-12 99-95 100-06 Per cent total ash in ; each . . . . . . , 1 CO o 040 1 0-70 2-50 3-08 5-25 1-62 x\mong the variations in composition in the ash from different parts of the wheat grain, the most noticeable are the very marked increase in the proportion of potash and lime toward the interior of the grain, and the still greater decrease in the proportion of magnesia in the same direction, that is, from the bran to the whitest flour. {Bulletin, Arkansas Aqric. Expt. Station . 1896.) 148. Organic Constituents : Fatty Matters. — Of the numerous organic bodies found in wheat, fat has not been chosen as the first to be described because of its importance as a grain constituent, but because it has the simplest composition of the organic bodies present, and therefore may fitly serve as an introduction to the chemistry of the more complicated com- pounds to follow. All grains contain more or less fat ; rice has the least quantity, viz. 0*1 per cent. ; maize and oats have respectively 4*7 and 4*6 per cent. ; wheat occupies a medium position with a percentage of 1 -2 to 1*5. The fat of wheat is not equally disseminated through the grain, but is almost entirely contained in the germ and husk or bran. An analysis by Church gives the quantity of fat in “ fine wheat flour "" as 0*8 ; it is, how- ever, doubtful if this analysis were made since the time when the problem of degerming flour has received so much attention from the miller. It has been already explained that the fats are salts of certain acids, with glycerin as a base. They are characterised by their unctuous nature, and by leaving a greasy stain on paper or linen. Fats are insoluble in water, and from their low specific gravity float on the surface of that liquid. On the other hand, all fatty bodies dissolve readily in either ether or light petroleum spirit. As food stuffs, the fats occupy a high position ; in tables giving the relative nutritive value of different articles of food, fat heads the list. -If this were the only point to be considered, the presence of fats in v'heat and flour would be highly advantageous. They have, unfortunately, one great drawback, and that is that they become rancid on standing. This effect is particularly noticeable in flour imperfectly freed from germ. The rancidity is due to slow oxidation of certain constituents of the fat ; this change may proceed sufficiently far to seriously affect the flavour of the MINERAL AND FATTY MATTERS. 71 flour, without the fat as a whole being very greatly changed. The fat of wheat is of a light yellow colour, melts at a low temperature, and gradually darkens in colour on being kept. This change proceeds rapidly in the fat when maintained at a temperature of 70 or 80° C. Kdnig states that the fat of rye, a grain very similar to wheat, has the follovdng composition : — Glycerin . . . . . . . . . . 1 *30 per cent. Oleic acid . . . . . . . . .. 90*60 ,, Palmitic and stearic acids . . . . . . 8*10 ,, According to Konig, therefore, the fat of rye consists largely of free fatty acids, the glycerin present being insufficient to neutralise but a small ])roportion of the acids present. Stellwaag states that the fat of barley as extracted by ether has the following composition : — Free fatty acids Neutral fats Lecithin . . Cholesterin 3*62 per cent. 7*78 „ 4-24 An examination of wheat fat in the authors' laboratory gave the follow- ing results : A sample of perfectly fresh wheat germs was obtained from the miller and extracted repeatedly with light petroleum spirit in the cold. The extract was filtered, the spirit distilled off, and the residue heated very gently until completely free from the odour of petroleum. A light yellow oil, which in twenty-four hours deposited a trace of crystalline fat, was the result. The following analytic data were obtained on the thoroughly mixed oil and fat : — Free fatty acids . .. .. .. 5*92 per cent. Neutral fats . . . . . . . . . . 94*08 ,, 10000 More detailed analysis gave the following results : — Lower fatty acids (reckoned as butyric) . . 0*11 per cent. Higher fatty acids (palmitic, stearic, etc.) 20*72 ,, Oleic acid . . . . . . . . . . 52*24 ,, The fat completely saponified very readily. Spaeth (p. 233, Analyst, 1896) gives the following analytic data as to the properties of wheat fat : — Specific Gravity at 100° C. (water at 15=° 1) .. 0*9068 Melting Point of Fatty Acids . . . . . . 34° Saponification Value . . . . . . . . .. 166*5 Iodine Value .. .. .. .. .. .. 101*5 Reichert Meissl Value . . . . . . . . . . 2*8 Refractive Index at 25° C. .. .. .. 1*4851 ,, j, on Zeiss's Refractometer Scale 92*0 149. Wheat Oil : de Negri, and Frankforter and Harding. — ^A somewhat exhaustive examination of the oil of wheat has been made by de Negri, who found the separated germs of wheat to contain 12*5 per cent, of fatty matter, of which 8 per cent, could be extracted by petroleum spirit. On removal of the solvent by distillation in a vacuum, there remained a clear yellow-brown mobile oil having a peculiar smell resembling that of wheat. 72 THE TECHNOLOGY OF BREAD-MAKING. This oil solidifies at 15° C. It is soluble in ether, petroleum ether, chloroform, and carbon disulphide ; but is insoluble in cold absolute alcohol, though soluble, however, in thirty parts of hot alcohol. Glacial acetic acid dis- solves at 65° C. an equal volume of oil. It is only slowly saponified by alcoholic potash. Colour reactions : Haydenreich’s reaction, orange-yellow with violet spots. Brulle’s reaction, red tinge becoming blood red. Schneider’s and also Baudoin’s reaction gave no colour. Becchi’s as well as Milliau’s reac- tion gave a pale brown colour. The oil easily turns rancid. After standing a year a sample contained 43*86 per cent, of free acid calculated as oleic acid. Germs of different origin were found to give oils with varying con- St 3;Tlt S Frankforter and Harding state that the oil extracted from the germ by ether has a golden yellow colour, and a characteristic odour of freshly ground wheat. Warmed to 100° C., the oil becomes reddish-brown. It is a non-drying and not readily oxidisable oil. The following are the more important constants and particulars of composition as determined by de Negri, and Frankforter and Harding respectively Data. Specific Gravity at 0° C. . . „ . 15°C Solidification Point Melting Point of Fatty Acids Solidification Point of Fatty Acids Saponification Value Iodine Value of Oil Fatty Acids Refractometer Value (Zeiss-Wollny) Free Acid calculated as Oleic Acid Glycerol (glycerin) . . Lecithin Paracholesterol De Negri. Frankforter and Harding. _ 0*9374 0*9245 0*9292 15° C. — 39*5° C. — 29*7° C. — 182*81 188*83 115*17 115*64 123*27 — 74*5 I ( 4*07* 5*65 1 1 1 20*46 1 7*37 1*99 — 2*47 The figure marked by an asterisk is the amount per cent, of potassium hydroxide, KHO, required to neutralise the free acid. This figure X 5*027 = the acidity calculated as oleic acid. It will be seen that this sample is about four times as acid as that of de Negri. But like other oils, the acidity varies considerably with age and other conditions, {de Negri, Chem. Zeit 1898, 22 , 976, and Frankforter and Harding, Jour.Amer. Chem.Soc., 1899, ' 758 .) it is unusual to find germ oil with any brown tint as described by de Negri, pure germ is very pale yellow in colour and so also is the oil extracted therefrom. Possibly the germ on which de Negri worked contained a slight .amount of bran from which the oil derived its colour. Further explanation of the various analytic data will be given when •dealing more fully with fats in the confectionery section of this work, Chapter XXXIII. Experimental Work. 150 . The student who proposes to master for himself the contents of ithis work, should endeavour to verify as many as possible of the various MINERAL AND FATTY MATTERS. 73 statements and descriptions by direct experiment. The following outline of experimental work is intended as a laboratory course of study on the subject. 151. Mineral Constituents. — ^Take a small quantity of whole wheaten meal, heat it to redness over a bunsen in a shallow platinum capsule or basin. At first the volatile constituents of the grain burn with flame, leav- ing a black mass of carbon and ash. Continue the application of heat until the carbon entirely burns away, leaving behind a greyish white ash. To this, when cool, add water ; notice that most of it dissolves ; add a few drops of hydrochloric acid, filter the solution, and make a qualitative analy- sis of it ; test specially for calcium, magnesium, potassium, and phosphoric acid. It is well to test direct for these two latter constituents in separate small portions of ash. To test for potassium, dissolve up a portion in hydro- chloric acid, filter and add a few drops of platinum chloride to some of the solution in a watch-glass, the presence of potassium is demonstrated by the formation of the yellow precipitate of the double chloride of platinum and potassium. Dissolve another portion of the ash in nitric acid, filter and add nitric acid and ammonium molybdate solution ; after standing for some time in a warm place, phosphoric acid throws down a canary-yellow precipitate. 152. Fat. — ^In a tightly corked or stoppered bottle, shake up together some wheat meal and ether (or light petroleum spirit), allow the mixture to stand for an hour, giving it an occasional shake meanwhile. At the end of that time filter the solution through a paper into a clean evaporating basin and allow it to spontaneously evaporate. Notice that it leaves a small quantity of fat in the basin. Remember that the greatest care must be taken in all experiments with ether to avoid its taking fire. It is best to make this experiment in a room where there are no lights. CHAPTER VI. THE CARBOHYDRATES. 153. Definition of “ Carbohydrates.” — ^This name has been applied to a class of bodies composed of carbon, hydrogen, and oxygen, in which the latter two elements are present in the same proportion as in water, namely, two atoms of hydrogen for every one of oxygen. Thus, for example, starch contains to the six atoms of carbon, ten atoms of hydrogen to five atoms of oxygen. The carbohydrates comprise, among their number, bodies differing considerably in physical appearance and character, but yet exhibiting signs of close chemical relationship. Subjoined is a table of the more important carbohydrates, arranged into three groups, according to their empirical or simplest possible formulae : — Classification of Carbohydrates. 1 . Glucoses, Hexoses (C6H12O6). 2 . Sucroses or Saccharoses, Di-hexoses (C12H22O11). 3. Amyloses, Poly-hexoses n (C6H10O5). + Dextrose — La3vulose Galactose +Cane Sugar 4- Lactose + Maltose + Starch -J- Dextrin Cellulose Gums 154. Constitution of Carbohydrates. — Some reference has already been made to the glucoses in the chapter on organic compounds. It is there shown that closely allied to the aldehydes is a family of compounds known as aldoses. Of these, the formula of hexose, one form of which is glucose, has been given and explained. In both aldehydes and aldoses, there occurs the carbonyl (CO) group in which the oxygen is directly united to the carbon by its two links or bonds. It will be noticed that this group is attached to the free end of the open chain of carbon atoms. Glucose has been regarded as an aldehyde of mannitol, and may be formed by processes of moderate oxidation from that alcohol : — CHoHO CHHO CHHO CHHO CHHO or C«H8 (HO)o + 0 ICHsHO Mannitol. Oxgyen. (CH2HO CHHO CHHO CHHO CHHO 'COH or CfiHiaOe + H.O. Glucose. Water. Conversely upon reduction, glucose takes up two atoms of hydrogen and is converted into mannitol. The formula given shows the composition and relationship of glucose, which name is now more specifically applied to dex- trose. Lsevulose, called also fructose, has the same simplest formula as dextrpse, CeHisOg, and like it contains the radical carbonyl. There is, liowever, this difference, the carbonyl is attached not to one of the free atoms of the carbon chain, but to the last but one, thus showing lsevulose to be a ketose and closely allied to butyl-methyl ketone. The sucroses may be regarded as bodies formed by the union of two molecules of the glucose type, with the elimination of a molecule of water. THE CARBOHYDRATES. 75 a reaction, however, whicli does not occur anything like so readily as the decomposition of a sucrose into its component molecules of glucose. Thus under the influence of weak acids cane sugar splits up into glucose and fructose : — CioH220ii+H20=CH2HO-(CHHO)4COH+CH2HO.(CHHO)3-COCH2HO. Cane sugar. Glucose, Dextrose. Fructose, Lsevulose. The structural composition of cane sugar is not indicated in the above ecpiation, but the formulae of the resultant products show them to be re- spectively an aldose and a ketose. Owing to their composition, the sucroses are regarded as di-hexoses. The amyloses are much more complex bodies than are the preceding groups. They depart still further from the simplest hexose type, inasmuch as another molecule of water has been eliminated. This is clearly shown in the following specially written formulae : — Ci 2 H 240 i 2 * O12H22O11. C42H20O10. [Two Molecules of Glucose. One Molecule of Sucrose. Two “ Units ” of Amylose. The molecules of the amyloses are high multiples of the unit group, C 0 H 10 O 5 . From their complexity they are termed poly-hexoses. Brown and Morris in 1888 and 1889 contributed to the Chemical Society's Journal important papers on the Molecular Weights of the Carbohydrates. Their researches were based on RaoulCs investigations on the lowering of the freezing point of a solvent by the solution in it of any substance. (Thus, salt water freezes at a lower temperature than pure water.) Raoult found that equivalent molecular proportions of different compounds cause under the same conditions a similar depression of the freezing point of the solvent. This offers a valuable means of determining molecular ’weight, as, knowing that of one body dissolved, that of others may be determined. Brown and ]\Iorris applied this method to the investigation of the carbohydrates.' Molecular Constitution of Carbohydrates. Substance. Formula of Molecule. Dextrose Cane Sugar . . Cane Sugar, same solution after inversion"^' Maltose Lactose, Milk Sugar Arabinose . . Raffinose Mannite or Mannitol Galactose f . . Maltodextrin Amylodextrin Lowest or Stable DextrinJ Soluble Starch C6H42O6 C12H22O11 CcHipOe C42H22O11 Ci2H2204i C5H10O5 C18H32O16. 5H2O C«Hs(HO)b C6H4206 C12H220H I (Ci2H2o04o)2 j C12H22O11 (Ci2 H2 oOio)6 2OC12H20O10 5(Ci2H2oOio)20 Molecular Weight. 180 342 180 342 342 150 594 182 180 990 2,286 6,480 32,400 * Cane Sugar after inversion is split up into dextrose and laivulose, and dextrose having a molecular weight of 180 , so must lsevulose, and be represented by the formula CfiHioOfi. t Galactose is the “ dextrose ” of lactose. t The molecular weight, not only of the lowest or stable dextrin, is represented by the formula (C12H20 O|o)2c» but so also are those of the so-called higher dextrins, of which Brown and Morris examined a series. They find that “ the numbers obtained with dextrins occupying very different positions in the series are strikingly identical.” 76 THE TECHNOLOGY OF BREAD-MAKING. The above table contains the results of their determinations, which molecular weights, with the exception of that of starch, were obtained by direct estimations. In this latter case the direct method was inapplicable, and, accordingly, recourse was had to an indirect method, based on the generally accepted hypothesis that the starch molecule must be at least five times the size of the dextrin molecule produced under certain conditions. Mannitol, having such an intimate relationship in constitution to the carbo- hydrates, is also included in the table. It will be seen that, commencing with those most simple in constitution, the glucoses come first, and the amyloses last in order. In nature also no doubt the simpler bodies are first produced, and from these those which are more complex. In flour as a product of the finished and ripened grain, by far the greater part of the carbohydrates present is in the form of starch, and the chemistry of these bodies, in so far as bread-making is concerned, deals with the degradation or breaking down of the starch molecule into simpler substances, rather than with its building up. For this reason it will be preferable to begin our study of the carbohydrates with the amyloses, and then proceed to the other members of the family. Cellulose, TiCeHioOs. 156. Occurrence and Physical Properties. — ^This body, of which there are numerous physical modifications, constitutes the framework or skeleton of vegetable organisms, in which it acts as a sort of connective tissue, bind ing and holding together the various parts and organs of plants. Woody fibre consists largely of cellulose and one or two closely allied substances, among which is lignin, a harder and more resistant body than cellulose, but of somewhat similar composition. The pith of certain plants is nearly pure cellulose. Manufactured vegetable fabrics, as cotton and linen goods, and likewise unsized paper, are also cellulose in an almost pure form. Chemically pure Swedish filters con- sist of cellulose with only the most minute traces of other bodies. The horny part of certain seeds, such as “ vegetable ivory,'’ consist of a form of cellulose, which is of interest as being a “ reserve ” store of nutriment, as starch is in wheat and other seeds. Pure cellulose is white, translucent, of specific gravity of about 1*5, and is insoluble in water, alcohol, ether, and both fixed and volatile oils. An ammoniacal solution of copper hydroxide dissolves cellulose completely ; this reagent may be prepared by precipitating copper hydroxide from the sulphate, by sodium hydroxide, and then dissolving the thoroughly washed precipitate in strong ammonia. This solution dissolves cotton wool, or thin filtering paper, forming a sirupy solution ; on the addition of slight excess of hydrochloric acid, the cellulose is precipitated in flaky masses ; these, on being washed and dried, produce a brittle horny mass. This re- precipitated cellulose is not coloured blue by iodine, and still presents the same chemical properties as ordinary cellulose. 156. Behaviour with Chemical Reagents. — Cellulose, on being boiled with water under pressure, is converted into a body bearing some resemblance to dissolved starch, inasmuch as it is coloured blue ‘by iodine. The same effect is produced more rapidly by treatment with acids. Boiling with dilute sulphuric or nitric acid, or strong hydrochloric acid, breaks up cellu- lose into a flocculent mass, but without any change in composition. Treat- ment with stronger nitric acid changes cellulose into nitro-substitution pro- ducts called gun cottons or pyroxylin ; while that acid, in a yet more con- centrated form, oxidises cellulose to oxalic acid. By the action of strong sulphuric acid, cellulose is converted into a form of sugar known as cello- THE CARBOHYDRATES. 77 biose, C 12 H 22 O 11 . Concentrated solutions of potash or soda also dissolve cellulose, with the formation apparently of the same compound. Sulphuric acid, diluted with about half or quarter its bulk of water, has a most remark- able action on unsized paper. The paper on being dipped in the acid for a few seconds, and then washed with weak ammonia, is found to be changed into a tough parchment-like material, which may be used for many of the purposes to which animal parchment is applied. This body is familiar to confectioners, as being sold under the name of parchment paper for tying down pots containing jam and other substances. Filter papers, on being momentarily immersed in nitric acid of density 1 *42, are remarkably tough- ened, the product being still pervious to liquids and therefore suitable for filtering purposes. Such papers are recommended for filtering bodies that have to be removed from the paper while wet, and are now sold commercially for that purpose. 157. Existence in Wheat. — ^There are three forms of cellulose present in wheat, of which the following is a brief description ; — 1. The lignified or woody cellulose of the bran, which is entirely removed in the process of making white flour. In whole-meal, which contains the bran, the lignified cellulose undergoes no change in the operations of bread- making, nor afterwards during the processes of human digestion. 2. The parenchymatous cellulose, which forms the cell-walls of the endosperm. This disappears during germination of the grain, and is far more easily dissolved by all reagents than is lignin or woody cellulose. 3. So-called starch cellulose constitutes the envelopes or cellulose- skeleton of the starch cells. It is this form which is most readily converted into the starch-like body, giving a blue colouration with iodine. 158. Composition. — ^The formula, CeHioOs, is the simplest that can be derived from the percentage composition of cellulose, but there is little doubt that the molecule really consists of a number of groups of CeHioOs united together, and is at least as complex as that of starch. Starch ^ v (Ci2H2oOio)20 (Ci2H2oOio)20 (Ci2ll2oOio)20 (Ci2H2oOio)20 (C12H20O10) 20 159. Occurrence. — ^The starchy matters of wheat are of vast importance as constituting the greatest portion of the whole seed. Starch is not only found in wheat, but also in other seeds ; and in fact in most vegetable substances used as food. From whatever source obtained, starch has the same chemical composition, but varies somewhat in physical character. 160. Physical Character. — Starch, when pure, is a glistening, white, inodorous granular powder. If a pinch be taken and squeezed between t!ie thumb and finger, a peculiar “ crunching (crepitating) sound is heard. Starch has a specific gravity of from 1*55 to 1*60. Starch is extremely hygroscopic, absorbing moisture with avidity ; in the form in which it is usually sold it contains about 18 per cent, of water. Wheat starch after drying in a vacuum still retains about 11 per cent, of water. Heating in a current of dry air to a temperature of 110° C. renders it practically anhydrous. 161. Microscopic Appearance. — ^The microscope shows starch to be composed of minute grains, each having a well defined strueture. These grains are respectively termed starch cells, granules, or corpuscles. Care- ful examination reveals that each cell consists of an outer coating or pellicle formed of a very delicate type of cellulose, to which the name “ starch 78 THE TECHNOLOGY OP BREAD-MAKING. Plate I. IfheaJt/. JPcftccto. Microscopic Sketches of Various Starches. JUia^nificdL a^outy HJO ciiajTvefX/'S. £E.TulUr THE CARBOHYDRATES. 79 cellulose is applied. This envelope is built up of several layers, arranged concentrically one over the other, and contains within its interior a sub- stance which may be called starch proper, in distinction from the enclosing matter. This starch proper is also termed “ starch granulose or “ amy- lose."" On careful examination these separate coats appear as a series of more or less concentric rings, having for a nucleus a dark spot or cross, termed the “ hilum."' The actual size and shape of starch cells vary with the source from which the starch is derived ; thus the grains of starch from potatoes are comparatively large, while those of rice are extremely minute. When examined by polarised light certain starches exhibit characteristic appearances — these are referred to in detail in the table following. A description of the phenomena of polarisation is given in Chapter IV. It is possible in many instances to determine the origin of a sample of starch by its microscopic characteristics ; it follows that impurities may similarly be detected ; also, as all vegetable adulterants of flour contain starch, admix- ture of other grains, as maize, rice, etc., is in this manner revealed. In Plate I is given the appearance of the more important starches as seen under the microscope. Microscopic Characters of Various Starches. 162. Wheat. — ^Wheat starch is extremely variable in size, the diameter of the corpuscles being from 0*0022 to 0*052 m.m. (0*00009 to 0*0029 inch). Many observers point out that medium sized granules are comparatively absent. The grains are circular, or nearly so, being at times somewhat flattened. The concentric rings are only seen with difflculty ; the hilum is not so visible as in certain other starches. Polarised light shows a faint cross. In old samples of wheat or flour the granules show cracks and fissures : this applies more or less to all starches. 163. Barley. — Granules more uniform in size than those of wheat, also somewhat smaller ;] average diameter 0*0185 m.m. (0*00073 inch) ; a few exceptionally large granules may be found measuring as much as 0*07 m.m. Shape, slightly angular circles. Concentric rings and hilum either invisible or only seen with difficulty. 164. Rye. — ^Diameter of granules from 0*0022 to 0*0375 m.m. (0*00009 to 0*00148 inch). Taking a whole field, the average size of granules is usually somewhat higher than those of wheat. Shape, granules are almost perfectly round, here and there show cracks. Concentric rings and hilum only seen with difficulty. 165. Oats. — ^Diameter of granules, 0*0044 to 0*03 m.m. (0*00017 to 0*00118 inch). Granules are angular in outline, varying from three to six- sided. 166. Maize. — ^Diameter of granules, average size, 0*0188 m.m. (0*00074 inch). Shape, from round to polyhedral, mostly elongated hexagons, with angles more or less rounded. Concentric rings scarcely visible, hilum star- shaped. 167. Rice. — ^Diameter of granules from 0*0050 to 0*0076 m.m. (0*0002 to 0*0003 inch). Granules are polygonal in shape, mostly either five or six- sided, but occasionally three-sided. Are usually seen in clusters of several joined together. A very high magnifying power shows a starred hilum. 168. Potatoes. — ^Diameter of granules from 0*06 to 0*10 m.m. (0*0024 to 0*0039 inch). The granules vary greatly in shape and size ; the smaller ones are frequently circular ; the larger grains are mussel or oyster shaped. 80 THE TECHNOLOGY OF BREAD-MAKING. The hilum is annular, and the concentric rings incomplete, but, especially in the larger granules, clear and distinct. The rings are distributed round the hilum in very much the same way as the markings show on the outside of a mussel shell. With polarised light a very distinct dark cross is seen,, the centre of which passes through the hilum. 169. Canna Arrowroot, or Tous les mois. — ^Diameter of granules varies from 0-0469 to 0*132 m.m. (0-0018 to 0*0052 inch). The shapes differ con- siderably, from round to more or less elongated ovals. The hilum is eccen- tric ; the rings are incomplete, extremely fine, narrow and regular. Under polarised light a more distinct cross is seen than with the potatoes. 170. Preparation and Manufacture of Starch. — ^For experimental pur- poses, starch can readily be obtained from wheaten flour by first preparing a small quantity of dough ; this is then vTapped up in a piece of fine muslin, or bolting silk, and kneaded between the fingers in a basin of water. The milky fluid thus produced deposits a white layer of starch on the bottom of the vessel, which may be carefully air-dried. The starch of barley and the other cereals may be obtained in a sufficiently pure form for microscopic study in the same manner. Potatoes require to be first scraped, or rubbed through a grater, into a pulp ; this pulp must then be enclosed in the muslin and the starch washed out. On the manufacturing scale, starch is obtained from wheat and other- grains by first coarsely grinding and then moistening the meal with water. This is allowed to stand, and after three or four days fermentation sets in, more water is then added, and the putrefactive fermentation allowed to- proceed for some three or four weeks. By the end of this time the gluten and other nitrogenous matters are dissolved. They are then readily sepa- rated from the starch by washing, after which the starch is dried. Starch is now largely manufactured from rice by a process in which the grain is sub- jected to the action of very dilute caustic soda, containing about 0*3 per cent, of the alkali ; this reagent dissolves the nitrogenous bodies and leaves- the starch unaltered. The so-called “ corn flour ” is the starch of maize prepared after the same fashion. Potato starch is obtained by first rasping tlie Avashed potatoes into a pulp by machinery ; the pulp is next washed in a sieve, the starch is carried through by the Avater, and after being allowed to subside is dried on a tile floor at a gentle heat. 171. Gelatinisation of Starch. — Starch is insoluble in cold Avater, and cannot be dissolved by any knoA\m liquid AAnthout change ; this folloAVS from its having a definite organic structure ; AAffien this is destroyed, as must of necessity be the case AA^henever a solid is rendered liquid, it cannot by any artificial means be again built up in the same form. As previously stated, the starch granules consist of an outer envelope of cellulose, enclosing AAffiat is termed “ amylose,” or starch proper. This latter body is soluble, and although pure starch in the granular form yields no soluble substance to Avater, yet if the cellulose envelopes be ruptured by mechanical means, it is then found that on treatment AAotli Avater at ordinary temperatures a soluble extract is obtained. When, hoAvever, starch is sub- jected to the action of boiling AA'ater a marked change ensues : under the influence of heat the little particles in the interior, by SAvelling, burst the containing envelope, and dissolving in the water form a thick and viscous liquid, A\4iich on cooling, if sufficiently concentrated, solidifies into a gelatin- ous mass. This solution of starch is someAAffiat cloudy, owing to the undis- solved particles of starch cellulose remaining in suspension. These may be,, in great part, removed by filtration. This bursting of the starch granules is frequently spoken of as the “ gela- THE CARBOHYDRATES. 81 tinisation of starch, and the resulting substance as “ starch-paste.'’ The temperature at which this change occurs varies with the nature and origin of the starcli. The following table gives particulars as to the gelatinising temperatures of starch from different sources. The figures to the left are those of Lipp- man, while to the right are given the results of a series of later determinations made by Lintner, and published in 1889. It may be taken that Lintner's temperatures are for complete gelatinisation. Temperature of Gelatinisation of Starch. Granules Gelatinisation. Complete Gelatinisation, Source of Starch. Swollen. Commenced. Completed. Lintner. °C. °F. °C. 1 °F. 1 =C. °F. °C. °F. Barley . . .37-5 99-5 57-2 135 62-2 144 80 176 Maize . . 50-0 122-0 55-0 131 62-2 144 75 167 %e 45-0 113-0 50-0 122 55-0 131 80 176 Potato . . 46-1 115-0 58-3 137 62-2 144 65 149 Rice 53-8 129-0 58-3 137 62-2 144 80 176 Wheat . . 50-0 122-0 65-0 149 67-2 153 80 176 Green Milt — — — — — — 85 185 Kilned Milt . . — — — — — — 80 176 Oats — 1 — — — 1 i 85 185 These temperatures of gelatinisation assume that the walls of the starch- containing cells have been broken down, and that excess of water is present ; otherwise the temperature of gelatinisation is considerably higher : thus, in stiff biscuit doughs, and even in bread, much of the starch remains un- gelatinised even after being baked. There is doubt as to whether or not gelatinised starch is in a state of true solution. When filtered, the clear filtrate gives a blue colouration with iodine (a characteristic reaction of starch), but on dialysis through an ani- mal or vegetable membrane, or even filtration through porous earthenware, the starch is removed. This has led to the view that the starch in starch paste is simply in a state of extremely fine division, but more probably the state is one of true solution, and the removal by filtration is due to the highly colloid nature of starch. 172. Soluble Starch. — On treating starch with dilute acids in the cold, the starch loses its power of gelatinisation, and becomes what is known as soluble starch.” In this form no change of appearance is observed in the granules, but the starch readily dissolves in hot water to a clear limpid liquid. Lintner directs soluble starch to be prepared in the following man- ner ; Pure potato starch of commerce is taken and mixed with a sufficient quantity of 7*5 per cent, hydrochloric acid to cover it, and allowed to stand either at ordinary temperatures for seven days, or for three days at 40° C. By that time the starch will have lost the power of gelatinisation, and is repeatedly washed with cold water until every trace of acid is removed. It is then air-dried, and is readily and completely soluble in hot water to a bright and limpid solution. Soluble starch is probably a polymeride of ordinary starch, and when dissolved, then known as “ starch solution,” closely resembles “ starch- paste ” in its chemical behaviour. G 82 THE TECHNOLOGY OF BREAD-MAKING. 173. Action of Caustic Alkalies on Starch. — ^Treatment with cold dilute solutions of potash or soda causes starch granules to swell enormouslj^ ; the volume of starch grains may thus be made to increase 125-fold. This reaction also serves for the differentiation of the various starches. H. Symons recommends the use of soda solutions of different strengths : a small quantity of the starch is shaken up in a test-tube for ten minutes with one of the soda solutions, and then a drop of the liquid is examined under the microscope. The following is a table of results thus obtained : — - A few Starch granules The greater number All dissolved in a solution of dissolved in a solution of dissolved in a solution of Potato 0*6 per cent. 0*7 per cent. 0*8 per cent. Oats . . 0*6 0-8 1-0 Wheat .. 0-7 0-9 DO Maize . . 0-8 DO „ M Rice .. DO „ 1*1 1-3 174. Action of Zinc Chloride. — ^Treatment with zinc chloride also causes a remarkable swelling of the granules of starch ; this reaction, when viewed under the microscope, serves admirably to show the structure of the cor- puscles. Some concentrated solution of zinc chloride is tinged with a trace of free iodine. A few grains of the starch are placed on a glass slide, to- gether with a small drop of this solution. No change is observed until a little water is also added. They then assume a deep blue tint, caused by the iodine, as explained in a subsequent paragraph, and gradually expand. A frill-like margin developes round the granule, the foldings of this frill open out in their turn, until the granules at last sw^ell up to some twenty or thirty times the original volume, and then appear as limp-looking sacs. These changes, so far as can be seen, are not accompanied by any expulsion of the inner contents of the cell. 175. Properties of Starch in Solution.— A solution of starch is colourless, odourless, tasteless, and perfectly neutral to litmus. Starch is a highly colloid body, and can be readily separated by dialysis from crystalUne sub- stances. On evaporating a solution of starch, it does not recover its original insolubility. Starch solution causes right-handed rotation of polarised hght. Starch amylose is insoluble in alcohol, and may be entirely precipitated from its aqueous solution by the addition of alcohol in sufficient quantity. Tannin precipitates both starch-paste and soluble starch, the precipitate being re-dissolved on heating. Barium hydroxide gives an insoluble com- pound with solution of starch, and is used in this way in some processes of starch estimation. Soluble starch, owing to the formation of a hydriodide of starch (C 24 H 4 o 02 oI) 4 HI, is coloured an intense blue by the addition of iodine in extremely small quantities. This blue colouration disappears on heating the solution, but reappears on its being cooled. This reaction is exceedingly deli- cate, and is practically characteristic of starch. For the purpose of this test, the iodine may be dissolved in either alcohol or an aqueous solution of potassium iodide ; for most purposes preferably the latter. For the occurrence of tliis reaction, the presence of water is apparently essential ; for if wh eaten flour be moistened with an alcoholic solution of iodine no colouration is produced other than tlie natural brownish yellow tint of tincture of iodine. But with a potassium iodide solution the flour assumes a blue colour so intense as to be almost black. The iodine colouration of starch is only caused by free iodine, not by iodine compounds ; and is not produced except in the presence of hydriodic acid or an iodide. Potash or soda in solution, when added to dissolved iodine, immediately combine therewith to form THE CARBOHYDRATES. 8.3 iodides and iodates ; consequently, the iodine test for starch is inapplicable in an alkaline medium. In case a solution to be tested for starch is alkaline to litmus, cautiously add dilute sulphuric acid, until neutral or very slightly acid ; the test for starch may then be made. The only compounds usually likely to interfere with the iodine reaction for starch are some of the dextrins ; these bodies combine with iodine, forming either colourless or brown com- pounds ; but unless present in large quantities do not prevent the detection of starcli. Iodine combines with starch more readily than with dextrin, consequently the iodine should in such cases be added in very small quan- tities at a time, when the blue colouration due to the starch will appear before the brown tint produced by dextrin. In testing for starch the addi- tion of iodine solution should be continued until an excess of iodine is present in the solution. In bodies such as starchless biscuits, of which washed gluten may form a constituent, it is sometimes found, on dropping a solution of iodine on the broken surface of the biscuit, that a blue colouration is produced, but that prolonged boiling fails to yield a solution which gives an iodine colouration. The probable explanation seems to be that under the influence of heat traces of starch cellulose in the biscuit products are converted into the soluble variety, and hence give a colouration in situ, but are in such small quantity and so firmly imprisoned within the cellulose as not to be liberated by boil- ing. It is not sufficient in making starch tests on solid substances to trust to adding iodine to the substance itself : the substance should also be ex- tracted with boiling water, and the test made on the filtered solution. Starch does not cause a precipitate with Fehling's solution, that is, it does not reduce an alkaline solution of copper sulphate in potassium sodium tartrate. See paragraph 182, on Reducing Power. Starch under the influence of heat, and readily when treated with certain other bodies, is transformed into others of the carbohydrates. Dextrin, SOCi^H^oOio, or WCeHioOj + H^O = 176. Occurrence. — ^Dextrin is principally known as a manufactured article, but also occurs in small quantities as a natural constituent of wheat and most bodies containing starch. 177. Physical Character. — ^In appearance, dextrin is a brittle transparent solid, very much resembling the natural gums, as gum arable. It is colour- less, tasteless, and odourless. Dextrin is a colloid body, and is very soluble in water, and it is also soluble in dilute alcohol ; but it is insoluble in absolute or even concentrated alcohol, by means of which it may be precipitated from its solutions. Dextrin is also insoluble in ether. Surfaces moistened with a solution of dextrin, and then allowed to dry in contact with each other, adhere firmly. Commercial dextrin has usually a more or less brown tint from the presence of caramel in small quantity. 178. Preparation. — Dextrin is usually prepared by the action of heat, with or without certain reagents, on starch. The starch may be maintainecl at a temperature of about 150° C. until it assumes a brown colour : treat- ment with water then dissolves out dextrin in an impure form. If the starch be first moistened with water containing a minute quantity of nitric acid, the change proceeds much more rapidly ; the starch should in this case be heated to about 200° C. The substance thus yielded is that known as British gum, and is largely used for sizing calicoes and other purposes in commerce. If starch solution be boiled with dilute sulphuric acid until it no longer gives a blue colouration with iodine, dextrin will be found in the solution, but mixed with maltose. Certain nitrogenous bodies also possess the power of converting starch into dextrin and maltose. 84 THE TECHNOLOGY OF BREAD-MAKING. 179. Chemical Character. — ^Dextrin was formerly supposed to consist of a mixture of polymeric bodies of closely similar chemical character. These several dextrins were separated into two groups by their difference in behaviour when treated with iodine solution. The members of one of these groups, known as “ erythro- dextrins,” were found to strike a reddish-brown colouration on treatment with iodine ; while the others, which were classified as “ achroo-dextrins,” yielded no colouration when iodine was added. It has already been stated that Brown and Morris in 1889 investigated the molecular weights of the carbohydrates, and that they found the results given by the various dextrins were practically identical. The formerly held theory assumed that the erythro-dextrins contained in the molecule 8 and 9 respectively of the group C 12 H 20 O 10 ; while the molecular formula of the achroo-dextrins included from 2 to 7 of the C 12 H 20 O 10 group. In face of Raoult’s method, giving identical molecular weights for the whole of the dextrins, the view of their being polymeric bodies is no longer tenable. The iodine colouration, produced by the so-called erythro-dextrins, is due to the presence of certain other bodies, termed “ amy loins,” which Avill subse- quently be described. Dextrin has a powerful action on polarised light, twisting the ray to the right : its name is derived from this property. A solution of dextrin in some respects resembles one of starch ; they are, however, distinguished by the dextrin giving no blue colour when treated with iodine. Dextrin was formerly supposed to exercise no reducing action on Fehling’s solution, and that in that respect its behaviour was similar to that of starch. But more recent observers, among whom are Brown and Millar {Journ. Chem. Soc., 1899), point out that dextrin has a reducing power of about R 5*8. The Sugars — Maltose, Cane Sugar, Milk Sugar, and Glucose. 180. General Properties. — ^As already explained, the sugars are a sub- division of the class of bodies known as carbohydrates ; they are character- ised by having a more or less sweet taste, and are soluble in water. Many are natural products occurring both in the animal and vegetable kingdom. 181. Maltose, C,2H220ii. — This body occurs in company with dextrin in starch solutions which have been treated with dilute sulphuric acid until the solution no longer yields a blue colouration with iodine. It forms a most important constituent of malt extract, amounting to from 60 to 65 2 ^er cent, of the total solid matter. In the pure state, maltose consists of small hard crystalline masses or minute needles, which are soluble in v^ater and dilute alcohol. Maltose, being a crystalline body, may be separated from dextrin by dialysis, and also by precipitating the dextrin by means of strong alcohol. A solution of maltose causes a right-handed rotation of a ray of polarised light. Maltose gives no colouration with iodine, but, in common with certain other of the sugars, exercises a reducing or deoxidising action on some metallic salts. 1 I: 182. Reducing Power. — ^This reducing action is most commonly tested by means of the reagent known as “ Fehling’s solution,” which consists of sulphate of coi)y)er, tartrate of potassium and sodium, and sodium hydroxide, dissolved in water. If sodium hydroxide be added to a solution of copper 1 sulphate, a })recipitate of copper oxide, CuO, combined with water, is thrown 1 down ; the sodium and potassium tartrate redissolves this and forms a deep blue solution, which may be boiled for some minutes without alteration. || Now certain varieties of sugar reduce the CuO to CU 2 O ; that is, they take i away oxygen, the change being represented by 2CuO = CU 2 O + G. The; oxygen is taken by the sugar, and for our present purpose need not be traced THE CARBOHYDRATES. 85 further. The CU 2 O, or copper sub-oxide, thus formed is insoluble in the Fehling's solution, and hence is precipitated, first as a yellow and then as a brick-red powder. The cupric oxide reducing power, or, more shortly, the cupric reducing power of a substance, has been defined by O’Sullivan as “ the amount of cupric oxide calculated as dextrose, which 100 parts reduce ” from Eehhng’s solution under usual conditions of analysis. By careful experiment is has been found that — 100 grams of dextrose reduce 220*5 grams of CuO. 100 ,, maltose ,, 137*8 ,, ,, If in the case of maltose the reduced CuO be assumed to be caused by dex- trose, and calculated as such, then — 22^ 5^^^ ~ ~ cupric reducing power of maltose. Another way of expressing the same thing is — The cupric oxide reduced by a given weight of dextrose being 100, the amount reduced by the same weight of any other body is taken as the cupric oxide reducing power of that body. For cupric reducing power the symbol K or k is employed, that is to say, the amount of reducing sugars calculated as dextrose from the CuO or CU 2 O precipitate =K. In the case of sugars resulting from changes produced in starch, the present more widely adopted rule is to take the reducing power of maltose as 100, and that of other bodies in terms of that of maltose. For the cupric reducing power thus expressed, the symbol R is employed. For example, if starch is converted into a mixture of bodies, one-fifth of which is maltose, and the remainder without reducing action, then the cupric reducing power of the mixture would be R 20. 183 . Cane Sugar, C12H22O11. — Cane sugar is widely spread in nature : it is found in certain roots, as beet-root, in the sap of trees, as the maple, and in the juice of the sugar cane. These natural solutions are first purified, and then the sugar obtained by crystallisation. The sugar found in per- fectly sound wheat is either identical with, or closely allied to, cane sugar. Pure cane sugar is colourless, odourless, and soluble in water, to which it imparts a sweet taste. Boiling water dissolves sugar in all proportions, while cold water dissolves about three times its weight. Sugar is insoluble in ether, chloroform, and petroleum spirit ; but is very slightly soluble in absolute alcohol, and sparingly soluble in rectified spirits of wine. The purest commercial form of sugar is that sold by the grocers as “ coffee sugar,” and consists of well defined crystals about three-sixteenths of an inch across. This, w^hen dried at 100° C. to expel any water that may be present, is sufficiently pure for most experimental w'ork with sugar. A solution of cane sugar exercises a right-handed rotation on a polarised ray of light. Cane sugar produces no colouration with iodine, neither does it cause any precipitate in Fehling’s solution. By the action of heat, cane sugar melts, and if then allowed to cool, forms the solid termed “ barley- sugar ” ; a prolongation of the heat results in giving the sugar a deeper colour. Many sweetmeats consist of sugar thus treated. The darkening in colour is due to the fact that at moderately high temperatures (210° C. = 410° F.) sugar begins to undergo decomposition. Watery vapour and traces of oily matter are evolved, leaving behind a substance soluble in w'ater, to which it imparts a rich brown tint. The characteristic sweet taste of sugar has then disappeared, and the liquid is no longer capable of fer- mentation by yeast. The change has resulted in the formation of a brown substance, termed caramel, to which the formula Ci 2 Hi 809 has been given. 86 THE TECHNOLOGY OF BREAD-MAKING. Caramel is, however, rather a mixture of bodies than a definite chemical compound. The browning of dextrin and starch when heated is also due to the formation of caramel. 184. Milk Sugar or Lactose, Ci2H220ti. — ^This sugar is principally of interest as being that present in milk, which contains quantities of it varying from 4 to 5 per cent. It will be noticed that the three sugars — maltose, cane sugar, and milk sugar — have all the same formula. 185. The Glucoses or Hexoses, C 6 H 12 O 6 . — ^Several modifications of glucose exist ; or these, two only are of importance in connection with the present subject, viz., glucose, otherwise known as dextrose or dextro- glucose, and fructose, called also laevulose or laevo-glucose. 186. Glucose or Dextrose. — ^This form of sugar exists as a natural pro- duct in the juices of many fruits, notably the grape and sweet cherry. The former yields about 15 per cent, of grape sugar. Glucose also occurs in the flowers of certain plants, and is derived from these by bees in the shape of honey, of which the glucoses are the principal constituents. Glucose is also found in large quantity in the urine of diabetic patients ; some doubt exists as to Avhether this sugar is absolutely identical with the glucose of fruits. Glucose, when pure, occurs in crystalline masses : it has a sweet taste ; but, weight for weight, is said to possess much less sweetening action than does cane sugar. (But see Chap. XXXIII.) A solution of glucose exercises a right-handed rotation on a ray of polarised light, and from this property has received the name of dextrose. Among the sugars, glucose is specially noticeable for the great ease with which it undergoes alcoholic fermentation. Like maltose, glucose exercises a reducing action on Fehling’s solution, producing a red precipitate of cuprous oxide. 187. Fructose or Laevulose. — This sugar occurs in company with glu- cose in certain fruits, and also in honey. Fructose crystallizes from an alcoholic solution in long crystals ; it possesses greater sweetening power than glucose, and offers more resistance to alcoholic fermentation. A solution of leevo-glucose exercises a left-handed rotation on a ray of po- larised light, thus distinguishing it from dextro-glucose ; the two names are })ased on the respective right- and left-handed rotary power of these glucoses. Laevo- and dextro-glucose both reduce Fehhng’s solution, but the reducing ])ower of fructose is rather the less of the two. 188. Commercial Glucose. — Glucose, in a more or less pure form, is largely manufactured for commercial purposes. Under the names of “ sac- charum,'’ “ invert sugar,’' etc., it is used as a substitute for malt by brewers and distillers. Various forms of confectionery and fruit jams contain glu- cose as an important constituent. Glucose occurs in two forms in com- merce ; ' the one is a thick and almost colourless syrup, the other is a hard crystalline body, varying in colour from almost white to pale brown. Glu- cose is usually made from starch by the action of heating with, dilute sulphuric or oxalic acid. For the purpose, either maize or rice is usually selected. Invert sugar is produced from cane sugar by heating with dilute acid. The following are analyses of different types of commercial glucoses I. Brewer’s solid starch glucose (Morris). II. Confectioner’s sirupy glucose (The authors). III. Brewer’s invert sugar (Morris). THE CARBOHYDRATES. 87 Glucose. . I. 57*16 II. .. 7*50 III. . . 66*92 Maltose . . 8*09 .. 60*92 — Sucrose . . — — . . 0*80 Dextrin . . 16*63 . . 16*20 — Proteins 0*97 — . . 0*59 Mineral matter 1*45 .. 0*18 1*59 AVater . . 15*70 . . 15*20 . . 22*21 Unfermentable matter, etc... 100 00 100 CO . . 7*89 100*00 The glucose in these commercial products is a mixture of dextrose and laevmlose. The sirupy glucoses consist principally of maltose and dextrin. ” Invert sugar '' is so called because such sugar rotates the ray of polarised light to the left instead of to the right, as does normal cane sugar. The Amyloins — Amylo-dextrin, M alto -dextrin. 189. Constitution. — ^The term “ amyloins ” was proposed by Armstrong as a convenient name for a group of bodies which are compounds of varying 2 :)roportions of the amylin or dextrin group, Ci 2 H 2 oOio, with the amylon or maltose molecule, C 12 H 22 O 11 . That these bodies are compounds and not mixtures is proved by their being incapable of separation by the action of alcohol, whereas mixtures of dextrin and maltose in the same proportions are readily so separated. Further, the amyloins are unacted on by ordinary yeast, SaccTiaromyces cerevisice, while the maltose of a mixture is readily so fermented. They are completely converted by diastase into maltose. ( C H O — ^This body is produced by the action Ui2Xl2oUioj6 of dilute acids on starch granules in the cold. After some weeks’ treatment the corpuscles become completely disintegrated, and then consist largely of amylo-dextrin ; this is dissolved in hot water and purified by precipitation with alcohol. This substance is a definite chemical compound, having the formula above assigned to it as the result of a determination by Raoult’s. method ; and is produced by the hydrolysis of starch. Amylo-dextrin gives an intense reddish-brown colouration with iodine, and its presence is the cause of the chemical properties hitherto ascribed to erythro- dextrin. 191. Malto-dextrin, x — When starch is converted by U'-'i 2 * 120 ^ 10 ) 2 diastase, malto-dextrin is found to a greater or lesser extent in the pro- ducts, especially when the converting action is not very prolonged. Malto- dextrin is unfermentable by ordinary yeast, Saccharomyces cerevisice, by the action of which it may be distinguished, and separated, from maltose. Malto-dextrin is, however, slowly fermented by certain secondary yeasts. Malto-dextrin cannot be separated into its constituents by the action of alcohol, but diastase completely and readily converts it into maltose. 192. Other Carbohydrates of Cereals. — ^There are certain other carbo- hydrate bodies, of which small quantities are found in wheat and other grains ; among these are : — Eaffinose, Ci8H320i8,5H20, is a sugar somewhat resembling cane sugar in character, but less easily inverted. Found by O’Sullivan in barley, a and /? Amylan, TiCeHioOs, are two bodies having the same empiric 88 THE TECHNOLOGY OF BREAD-MAKING. formula, which are found in the mucilaginous portions of grains. They are almost insoluble in cold water, dissolve in hot water, and gelatinise on cooling. These substances, when treated with dilute acids, are converted into glucose without the production of intermediate bodies. Wheat con- tains from 0*1 to 0-05 per cent, of a amylan, and from 2*0 to 2*5 per cent, of ft amylan. Extractive Matters . — Under this heading are included certain substances which cannot be readily identified in the same manner as starch, maltose, and other bodies. This is in consequence of their possessing no very definite chemical reactions. Lintner has obtained from barley a white amorphous substance of a gummy nature, to which the name xylan has been given, and which in composition is represented by the formula, CuH 2 oOio. Experimental Work. 193. Cellulose. — ^Mix in a moderate sized beaker about 5 grams of wheat meal, with 150 c.c. of water, and 50 c.c. of a 5 per cent, solution of sulphuric acid ; and set the beaker in a hot water bath for half an hour, giving its contents an occasional stir. At the end of that time add 50 c.c. of a 12 per cent, potash solution, and set the beaker in the bath for another half-hour. Observe that a residue remains ; allow this to subside, and wash it by de- cantation. Finally, transfer it to a filter, and let it drain. The substance thus obtained consists of the cellulose or woody fibre of the wheat. Add iodine solution to a portion, and notice that it produces no blue colouration. It is assumed that most of the students who go systematically through this course of experimental work will do so in a regularly appointed labora- tory ; they will there find the solutions of sulphuric acid and potash above referred to ready made up for use. Full directions for their preparation, and also of other special reagents required, are given in the chapters on analytic work toward the end of the book. Unless he has not access to such solutions, the student need not at this stage of his work trouble to specially prepare them. 194. Microscopic Examination of Starches. — Take a small quantity of either wheat meal or fiour and make it into a dough. Tie this up into a piece of muslin or bolting silk, and knead in a small cup or glass with water ; the starch escapes, giving the water a milky appearance, while the gluten and bran remain behind in the muslin. Clean an ordinary microscopic glass slide and cover, shake the starchy water and place a minute drop on the slide, lay on the cover, press it down gently, and soak up any moisture round its edge with a fragment of blotting paper. Place the slide on the microscopic stage, and focus the instrument, using first the inch and then the quarter or eighth objective. The separate starch cells are then plainly seen. Trace in a few of the cells on paper, with a camera lucida, and sketch in any points of detail. Measure one or two of the cells with the eye-piece micrometer, and mark their dimensions on the drawing. Take a small quantity of the flours respectively of barley, rye, rice, and maize, wash out the starch from each, and examine microscopicallyin pre cisely the same manner as with the wheat, making drawings in each case. A little corn flour, being practically pure maize starch, may be used instead of maize flour. Cut a potato in halves, and with a sharp knife scrape off a little pulpy matter from the cut surface, transfer to a slide, and examine with the microscope. Notice in each case the relative sizes of the granules, and compare their shapes. Examine for the hilum and also observe the rings. If the micro- scope be fitted with polarising apparatus, study the various starches under polarised light. THE CARBOHYDRATES. 89 195. Examination of Mixed Starches. — With separate portions of wheat flour, mix respectively small quantities of rice meal and corn flour. As before, knead the starch out of each, and examine the milky fluid for the foreign starches. Notice in the one case the very small rice starch granules, and in the other the somewhat larger maize starch granules interspersed among those of the wheat. 196. Gelatinisation of Starch. — Heat separate quantities of one gram of the starches of wheat, rye, maize, rice, and potato in 50 c.c. of water ; and notice the temperature at which the liquids commence to thicken through gelatinisation of the starch. The experiment is conducted in the following manner. Place a moderately large beaker on a piece of wire gauze over a tripod, as in Fig. 8. Take several small beakers or test tubes, and attach to each a wire hook, so that they may be hung over the edge of the large beaker. Fill this large beaker with w^ater, and use it as a water bath. Put the starch to be tested, together with the requisite quantity of water, in one of the small beakers, and suspend it in the water bath ; under which place a lighted bunsen. While the small beaker is thus being heated, stir its contents with a thermo- meter, and note the temperature at which the first appearance of gelatinisation is detected ; instantly remove the beaker and plunge it into a vessel of cold water. When cold, examine a little of the paste with the microscope, and notice whether or not many of the granules remain unaltered. Make a second experiment with the same starch, arresting the temperature at 2° hotter or colder, according to the degree of gelatinisation revealed by the microscope on the Fig. 8. — Apparatus for first trial. All the starches specified are to be determining Temperature tested m the same manner. Starch 197. Reactions of Starch Solution. — Gelatin- ise a little starch by heating it with water in a test tube or small beaker placed in the hot- water bath ; then let the solution cool. Dissolve some iodine in alcohol, and aqueous solution of potassium iodide, respectively. In each case use sufficient iodine to just give a sherry tint to the solution. Add some of either of these solutions (that in alcohol is commonly a “ tincture ”) to a small quantity of the solution of starch ; notice the blue colour produced. Heat the solution, and then allow it to cool ; observe the disappearance and gradual reappearance of the colour. Render a portion of the starch solution alkaline by the addition of caus- tic soda or potash ; to one portion of this solution add iodine ; notice that no colouration is produced. To the other, add dilute sulphuric acid until the solution is slightly acid to litmus paper. Then add some iodine solution, and observe that the normal blue eolour is produced. Add respectively solution of iodine in potassium iodide, and the tincture of iodine, to separate small portions of flour ; notice the dark blue colour produced in the first instance, and the sherry tint in the second. To the second portion add a little water ; the dark blue colour at once appears. Mount a minute por- tion of flour on a slide with iodine solu+ion ; examine under the microscope, and notice the blue colouration of the starch granules, while other consti- tuents of the flour remain comparatively uncoloured. 90 THE TECHNOLOGY OF BREAD-MAKING. 198. Dextrin. — ^Render some water faintly acid by the addition of a small quantity of nitric acid ; with this, moisten some starch in a porcelain dish, and maintain it at a temperature of 200° C. in a hot-air oven for about two hours. The hot-air oven is usually made of copper, and is heated by means of a bunsen placed underneath ; through a hole in the top a ther- mometer is fixed so as to show the temperature. Before using the oven, regulate the temperature by turning the bunsen partly on or off until the thermometer remains steadily within say 10 degrees of 200. The moistened starch must not rest direct on the bottom of the oven : it may be placed on a small tripod made by turning down the wires of an ordinary pipe- clay triangle. Treat this heated starch with hot Avater, and filter ; a yellowish-brown gummy solution is obtained. To a portion, add iodine solution ; notice that no blue colouration is produced, but instead a reddish-broAvn tint - starch, therefore, is absent. The reddish-broAAm colour is due to the presence of amylo-dextrin. From another portion of the solution, precipitate the dextrin by adding strong alcohol ; filter and AA^ash the precipitate Avith alco- hol, dissolve in a little Avater and reserve for a future experiment. Use a little of the solution for fastening together pieces of paper ; notice that it exhibits the ordinary properties of gum. 199. Maltose and other Sugars. — ^Take from 5 to 10 grams of ground malt, and mix AAdth ten times the quantity of Avater, place the mixture in a beaker arranged in a hot-water bath, and keep it at a temperature of 60° C. for half an hour : this may be done by turning doAAm the flame, or alto- gether removing it from time to time. The temperature may range from 55 to 65° C., but must not be alloAA^ed to go above the latter. At the end of the half-hour, raise the temperature to the boiling point for five minutes, and then filter ; the resultant liquid is a solution of maltose and dextrin, and may be used for experiments on maltose. Prepare solutions of the folloAA^ng substances, and test them Avith Feh- ling’s solution : (1) starch ; (2), the re-dissolved alcoholic precipitate of dextrin ; (3), aqueous extract of malt ; (4), cane sugar ; and (5), commer- cial glucose. Set some distilled Avater boiling in a flask or large beaker for half an hour. Take 20 c.c. of the mixed Fehling’s solution (see Chapter XXIX.), add an equal quantity of the boiled distilled Avater, and set in the boiling hot-Avater bath for ten minutes ; notice that no precipitate is produced. Heat five separ- ate portions of 20 c.c. of Fehling’s solution, and 20 c.c. of Avater to the boiling point, and add respectively 20 c.c. of the starch and other solutions pre- viously prepared. Let them all stand in the hot-Avater bath for ten minutes : at the end of that time some of the solutions aa411 probably be decolourised Avith the deposition of a copious red precipitate, Avhile others Avill remain unchanged. The results should be as folloAvs : — Starch — No precipitate. Dextrin — Very shght precipitate, due partly to the slight reducing action of dextrin itself, and partly also to the difficulty of thoroughly Avashing the dextrin free from maltose. Maltose — Red precipitate. Cane sugar — No precipitate. Glucose — Red precipitate. CHAPTER VIL THE PROTEINS. 200. Character of Proteins. — ^Tlie proteins, while not the most abundant constituents of wheat and flour, are yet among the most important. In whatever life exists, and in that physical basis of life, protoplasm, pro- teins are constantly and invariably present. In matters of animal origin, such as muscle, blood, milk, the proteins constitute a larger proportion of the water-free material than in most vegetable bodies, and much of the work of examining and classifying proteins has been first done on those derived from animal sources. All animal proteins are, however, derived either directly, or indirectly through the body of some other animal, from the proteins of the vegetable kingdom. The name protein is derived from the Greek (rpwretov, pre-eminence), and has been given to these bodies because of their great importance in the animal economy. Typical among the protein bodies is albumin, the essential constituent of the white of egg ; so much so that the term “ albuminous substance was often used as a synonym of protein. With a more minute classification of the proteins, the term albumin was restricted to one particular protein group ; and the term “ albuminoid,’' commonly employed as bearing the same meaning as “ pro- tein,” was restricted to gelatin and certain othe bodies which are not proteins, hut bodies bearing a resemblance or relationship to the group of which albumin is the typical member. ^ ^ 201. Nomenclature of the Proteins. — ^The proteins were formerly know- as proteids, but in view of the confusion arising from the lack of understands ing as to the exact sense in which the various names applied to protein- should be used, the Physiological Society and the Chemical Society con- jointly considered the subject through a Committee nominated by the two Societies. Their final report contained the following recommendations : — I- The word Proteid should be abolished. II. The word Protein is recommended as the general name of the group of substances under consideration. If used at all, the term Albuminoid should be regarded as a synonym of protein. The substances gelatin and keratin, which have hitherto been termed albuminoids in the limited sense in which physiologists have been accustomed to use it, should be called sclero- proteins (Proc. Chem. Soc., 1907, xxiii, 55). This restricted use of the term “ albuminoid ” has not, however, been universally adopted, as the word is still used as meaning the same as protein, while in more recent nomenclature the name has been appropriated to a small sub-group of “ simple proteins.” 202. Composition of Proteins. — ^The proteins are distinguished in com- position from the carbohydrates by their containing nitrogen and sulphur as essential constituents, in addition to carbon, hydrogen, and oxygen. They are substances of extremely complex constitution, and have very high molecular weights. They are colloid bodies, and for the most part uncrys- tallisable. The various proteins differ somewhat in composition : the following table gives the ranges of variation in percentages : — 91 ^2 THE TECHNOLOGY OF BREAD-MAKING. C H N S O From 50-0 6*9 15-0 0-1 20-9 To 55-0 7*3 19-0 2-0 23*5 From these figures various observers have attempted to assign empiric formulae to the proteins ; but in this there is some difficulty, as methods, such as that of Raoult which was so useful with the carbohydrates, cannot be applied to the proteins. Compounds are, however, known of egg albumin with copper, and of seed globulins with magnesium and other metals, and from these some idea of the complexity of the protein molecule can be gained. Thus the compound of one atom of copper with egg albumin has the following formula : CUC204H322N52S2O66, while tfrom the globulin metallic compounds the formula, C292H481N90S2O83, has been suggested for globulin. Plimmer gives C726HH74N194S3O214 as the formula of globin, the basis of haemoglobin. Within the last ten years Fischer and his co-workers have done much to make clear the actual constitution of the proteins. Plimmer in his monograph on the Chemical Constitution of the Proteins remarks that : “ The main results of these [Fischer’s] investigations is that the protein molecule is built up of a series of amino -acids, which form the basis of their composition, and of which [some eighteen] have been definitely determined.” By the condensation together, or combination with the elimination of mole- cules of water, the amino-acids are converted into a class of products which Fischer terms the “ polypeptides.” These form an essential part of the protein molecule, which may also, however, contain other groups such as phosphoric acid or possibly carbohydrates. Among the amino-acids which occur in proteins is a thio- or sulpho- acid, known as cystine, which is di-(^-thio-a-amino-propionic acid), and may be represented by the formula — SCH2CH(NH2)C00H. I SCH^CHlNH^jCOOH. Recent research has shown that cystine is the only sulphur-containing compound in the protein molecule, and consequently that the number of sulphur atoms in such molecule must be two or a multiple of two. As sul- phur is found in all proteins (except the protamines and histones), it follows that they must all contain cystine as an essential constituent. 203. Reactions of Proteins. — Protein substances are distinguished by their evolving ammonia on being strongly heated. This is at once noticed on burning pieces of quill or dried gluten, both of which consist largely of protein bodies. If the suspected substance be heated to near the boiling point of concentrated sulphuric acid, to which a little potassium sulphate lias been added, the whole of its nitrogen is converted into ammonium sul- phate, from which free ammonia is obtained by adding caustic soda in excess, and subjecting the liquid to distillation. This reaction forms the basis of wliat is known as Kjeldahl’s method for the determination of nitro- gen in org{\nic compounds. In examining substances for proteins, and especially in discriminating the various proteins from each other, their following characters are of importance — solubility, heat coagulation, indif- fusibility, action on polarised light, and colour reactions. Solubility . — All proteins are insoluble in absolute alcohol and in ether. vSome are soluble in water, others insoluble ; among the latter, many are soluble in weak saline solutions. Some proteins are soluble and others insoluble in strong or saturated saline solutions. THE PROTEINS. 93 Mineral and acetic acids, and also caustic alkalies, dissolve all proteins by the aid of heat, such solution being, however, accompanied by decom- position. The gastric and pancreatic juices also dissolve proteins, but, in so doing, change them into a sub-class of proteins, known as peptones. Heat Coagulation. — This is a very familiar characteristic of some pro- teins, chief among them being albumin from the white of egg, which on being plunged into boiling water assumes an insoluble form. Many pro- teins when dissolved either in water or dilute saline solutions are coagulated by the action of heat. The temperature at which coagulation occurs affords one method of determining the nature of the particular protein in the solu- tion. Distinct from heat coagulation is what is known as ferment coagula- tion, an instance of which is the coagulation of milk by rennet. Indiffusihility. — All the proteins (with the exception of the peptones) are highly colloid bodies, and when in solution may consequently be separ- ated from crystalline bodies by dialysis. Action on Polarised Light. — All proteins turn a ray of polarised light to the left, or are Isevo-rotatory. Colour Reactions — Xanthoproteic Reaction. — These are very useful methods of detecting and recognising proteins. The Xanthoproteic reac- tion is obtained in the following manner : Add to the solution under examination a few drops of strong nitric acid ; a white precipitate may or may not be produced, according to the nature and degree of concentration of the protein. (Peptones and some varieties of albumose give no precipi- tate.) Boil ; the precipitate or liquid turns yellow, with usually some solution of any precipitate. Cool and add ammonia ; the yellow liquid or precipitate turns orange. This colouration is the essential part of the reaction, and is the most delicate test for proteins we possess. Milton’s Reaction. — Dissolve, by the acid of gentle heat, one part by weight of mercury in two of strong nitric acid ; dilute with twice its volume of water, and allow the precipitate to settle ; the clear supernatant liquid is Millon's reagent. On the addition of a few drops of this to a solution of protein, a white precipitate forms, which, on being heated, assumes a brick- red colour. The reaction is prevented by the presence of sodium chloride. Other substances are precipitated by Mil] on’s reagent, but the precipitate does not turn red on boiling. PiotrowsH’ s or “ Biuret ” Reaction. — Add to the solution of albumin or similar protein a few drops of dilute solution of copper sulphate ; a precipi- tate of copper albuminate is formed, except with deutero-albumose and peptone. Add‘ excess of caustic potash or soda, a violent solution is pro- duced. Ammonia gives a blue solution. In the case of albumoses and peptones, the result is, instead, a rose-red solution with potash, and a reddish-violet with ammonia. Care must be taken not to add excess of sulphate, as so doing gives a reddish-violet colour, very difficult to distinguish from this peptone reaction. When this test is applied in the presence of salt solutions it may be somewhat modified : thus, magnesium sulphate is precipitated as magnesia by potash ; before the colour can be observed the precipitate must be allowed to subside. If ammonium sulphate is present, a large quantity of potash is necessary before the colour appears ; sodium chloride does not affect the reaction. 204. Precipitation of Proteins. — The preceding note on the solubility of proteins affords some clue to their various modes of precipitation, the pep- tones and albumoses being much more soluble than other proteins. Solutions of the proteins may be precipitated by the following bodies : — Strong mineral acids, especially nitric acid ; acetic acid ; and also with excess of sodium sulphate, sodium chloride, or magnesium sulphate. Salts 94 THE TECHNOLOGY OF BREAD-MAKING. of the heavy metals, as mercuric chloride or basic lead acetate, also precijh- tate proteins ; on suspending the precipitate in water, and passing a stream of sulphuretted hydrogen, the metal is precipitated and the protein recovered in an unchanged form. In addition, proteins are precipitated by tannin, or tannin and sodium chloride together ; by saturation with ammonium sulphate ; by picric acid ; and by alcohol in faintly acid solutions. Among these the following are convenient methods of removing proteins from a solution, either as a part of the process for their own isolation, or as a prior step toward examining the liquid for other substances : — 1. The solution is mixed Avith half its volume of a saturated solution of common salt, tannin is added in slight excess, and the proteins are entirely separated. 2. The solution is saturated AA'ith ammonium sulphate, which precipi- tates all proteins but peptones. 3. The solution is rendered faintly acid Avith acetic acid, several times its volume of absolute alcohol added, and allowed to stand tAA^enty-four hours. The Avhole of the proteins are thus precipitated. 4. When proteins of the albumin or globulin group only are present, simple acidulating and boiling the solution precipitates the proteins. 205. Glassification of Proteins. — ^Proteins are commonly divided into animal and vegetable proteins, according to their origin. Strictly speaking, the animal proteins have but little to do AAuth the present work, but as their classification is largely that on aaLIcIi the classification of those from vegetable bodies is also based, a short account of the animal proteins is here inserted. 206. Animal Proteins. — ^These are conveniently arranged in the foUoAv- ing groups : — Class I. Albumins, soluble in Avater, in dilute saline solutions, and saturated solutions of sodium chloride and magnesium sulphate. Precipi- tated from their solutions by saturation Avith ammonium sulphate. Coagu- lated by heat, usually about 70°-73°C. Members of class — Serum albumin, egg albumin, cell albumin, muscle albumin, lact-albumin. Class 2. Globulins, soluble in dilute saline solutions ; insoluble in water, concentrated solutions of sodium chloride, magnesium sulphate, and am- monium sulphate. Coagulated by heat, temperature varying considerably^ Members of class — Fibrinogen, serum globulin, crystallin ; vitelHn, in the yolk of egg, not precipitable by sodium chloride. Class 3. Albuminates, or Derived Albumins, derived from either albu- mins or globulins by the action of AA-eak acids or alkalies. On heating a solution of egg albumin to about 40° C. AA'ith a feAV drops of 0*1 per cent, sulphuric acid or 0*1 per cent, potash solution, the solution loses its pro- perties and becomes converted into acid-albumin or syntonin, or alkali- albumin respectively. Albuminates are soluble in acid or alkaline solutions or in Aveak saline solutions ; insoluble in pure Av^ater, precipitated like globulins by saturation Avith sodium chloride, magnesium sulphate, or ammonium sulphate. Solu- tions not coagulated by heat. Caseinogen, the chief protein constituent of milk, is an albuminate. Class 4. Proteoses, intermediate products in the hydration of proteins, formed in the body by the action of the gastric and pancreatic juices, arti- ficially by heating Avitli water, and more readily by dilute mineral acids. Are not coagulated by heat, precipitated by alcohol, all give the biuret reaction. Precipitated by nitric acid, precipitate soluble on heating, and reappearing as the liquid cools. THE PROTEINS. 95 The proteoses are subdivided into albumoses, globuloses, etc., according to the original protein from which derived, albumin, globulin, etc. Each group of proteoses may be further subdivided in a similar manner ; taking albumose, there are two varieties, liemi-albumose and anti-alhumose, which on further digestion are converted into hemi-peptone and anti-peptone respectively. Classified according to their solubilities, they are divided into — Proto-albumose, soluble in cold and hot water and in saline solutions ; precipitated like globulins by saturation with sodium chloride or magnesium sulphate. Hetero-albumose, insoluble in water ; soluble in 0*5-15 per cent, sodium chloride solution in the cold, but precipitated by heating to 65°. Precipi- tated from its solutions by dialysing out the salt, like globulins. Precipi- tated by saturation with salts. Proto- and hetero-albumose are often called primary albumoses, because they are the first products of hydration of proteins. Deutero-albumose, soluble in hot and cold water, not precipitated from its solutions by saturating with sodium chloride or magnesium sulphate, but precipitated by ammonium sulphate, is an intermediate stage in the conversion of the primary albumoses into peptone. Class 5. Peptones are the final product of the hydration of proteins ; further hydration splits up the peptone into simpler bodies, which are no longer proteins. The peptones are soluble in water, not coagulated by heat, and are not precipitated by nitric acid, copper sulphate, ammonium sul- phate, and a number of other precipitants of proteins. Precipitated, but not coagulated, by alcohol. Precipitated by tannin, picric acid, and other substances. They give the biuret reaction. Pure peptone may be separated from all other proteins by ammonium sulphate : the solution is then subjected to dialysis in order to remove the sulphate, and the peptone precipitated by alcohol. It may then be dried by washing with absolute alcohol, ether, and finally standing in desiccator over sulphuric acid, a vacuum being maintained in the desiccator by a sprengel or other air-pump. Peptone thus prepared hisses and froths on being dissolved in water, with evolution of heat. < Peptone is somewhat cheesy in taste, but not unpleasant. Artificially prepared peptones, as peptonised milk or beef extract, have a bitter taste. This is due, however, to some bitter substance not yet separated, native peptones and albumoses being almost tasteless. Hemi-peptones are split up by the pancreatic juice into simpler products, as leucine and tyrosine. Anti-peptone is not decomposed in this manner. Both varieties of peptone are readily dialysable ; albumoses are only slightly diffusible under similar conditions, while the albumins and globulins are highly colloid. Class 6. Coagulated Proteins . — (a) Coagulated by heat, are insoluble in water, weak acids, and alkalies. Soluble after prolonged boiling in con- centrated mineral acids, also in gastric and pancreatic juice with formation of peptones. (6) Coagulated by ferments, fibrin from blood, myosin from muscle, casein from milk. 207. Vegetable Proteins. — ^As previously stated, plants contain a less proportion of protein matter than animals. They may be found in solution in the sap or juice of plants, or in the solid state in the protoplasm of the plant cells, and in a comparatively dry condition in the ripe seeds. Protein is often found in granules (aleurone grains). Some of the vegetable proteins are obtainable in a crystalline form. The classification adopted for the animal proteins is in the main applied to those of vegetable derivation. 96 THE TECHNOLOGY OF BREAD-MAKING. 208. More Recent Official Classification. — In the years 1907 and 1908 committees were appointed by scientific societies in America and England respectively in order to settle a scheme of classification and nomenclature of the proteins. The American scheme was of the two the more complete, inasmuch as it definitely provided for the inclusion of the vegetable proteins. Their classification contained the following groups ; — I. The Simple Proteins. {a) Albumins. {h) Globulins. (c) Glutelins. {d) Alcohol-soluble Proteins (Prolamins). (e) Albuminoids. (/) Histones. {g) Protamines. II. Conjugated Proteins. {a) Nucleoproteins. (6) Glycoproteins. (c) Phosphoproteins. {d) Hsemoglobins. (e) Lecithoproteins. III. Derived Proteins. 1. Primary Protein Derivatives— (g) Proteans. {h) Metaproteins. (c) Coagulated Proteins. 2. Secondary Protein Derivatives — (а) Proteoses. (б) Peptones. (c) Peptides. Although the classification of the vegetable proteins largely follows that of animal proteins, the special character of those of vegetable origin necessi- tates some little modification of the definitions as deduced from the investi- gation of the animal compounds. The following explanations of the various classes are made vatli special reference to the vegetable section, and do not agree in every detail with the properties already given of the animal groups. 209. Simple Proteins. — Albumins. These have been already defined as “ soluble in water and coagulated by heat,’' but a more recent classifica- tion has been based upon the behaviour of albumins and globulins respec- tively to a half-saturated solution of ammonium sulphate. The portion of ])rotein which under these conditions remains in solution is regarded as albumin. This does not hold good with the vegetable albumins, since some at least are precipitated by this treatment. Again, in the case of the vege- table albumins it is often difficult to say whether such a body is soluble in ])ure water, or whether its solubility is due to the presence of small quanti- ties of mineral salts. One of the best studied vegetable albumins is the leu- cosin of wheat, and this is soluble in water containing merely the slightest traces of mineral matter. The following are examples of vegetable albu- mins — Leucosin from the seeds of viieat, rye and barley. Legumelin from the seeds of pea and lentil. Globulins. — The previous definition of these states them to be “ insolu- ble in water, soluble in dilute saline solutions ” ; but among the vegetable THE PROTEINS. 97 globulins are classed certain bodies Avhicli only have the properties of the globulins when existing as protein salts through combination with small quantities of acid. On being freed from this acid, they become soluble in water, and thus no longer conform to the definition of the class. From their mode of preparation it is nevertheless convenient to include them in this group. Globulins were formerly subdivided into two groups according to whether or not they can be precipitated from a solution by saturation with sodium chloride. This operation, known technically as “ salting-out,"" separates the bodies known as myosins from solution. Those remaining unchanged were termed vitellins. In the case of the vegetable globulins, this distinction does not hold good, as certain so-called myosins are in fact albumins, while some vegetable vitellins are only partly soluble in saturated sodium chloride solution. The body referred to as wheat myosin is really the albumin leu- cosin. All vegetable globulins, so far as has been at present ascertained, are completely precipitated by saturation with sodium sulphate at a tem- perature of 33° C. The animal globulins may all be coagulated by heat, but most of those of seeds are only imperfectly coagulated by heating their solutions even to boiling. A characteristic of a number of the vegetable globulins is that they may be obtained in a crystalline form, while others can be separated as minute spheroids. The following are examples of vegetable globulins : — Legumin from the seeds of pea and lentil. Tuberin from the tubers of potato. Unnamed globulin from the seeds of wheat. The globulin of wheat is mostly if not all contained in the embryo or germ. Glutelins . — These consist of proteins which are insoluble in neutral aqueous solutions, saline solutions, or moderately concentrated alcohol (about 70 per cent, spirit). The most characteristic and only well explored member of this group is the glutenin of wheat. Similar proteins probably exist in other seeds, such as those of rye and barley, and also, according to Rosenheim and Kajiura, in rice. The rice glutelin has received the name oryzenin, and is said to represent the greater portion of the protein of the seed. Prolamins . — Certain seed proteins are soluble in alcohol of from 70 to 90 per cent, strength. Representatives of this group have been obtained from all seeds of cereals except rice ; further, they have never been found in the seeds of any other family of plants. The suggestion has been made that these proteins should be called “ gliadins,"" but as that name has already been appropriated to alcohol-soluble protein of wheat, Osborne has proposed the group name of “ prolamins,"" because on hydration they yield consider- able quantities of proline and amide nitrogen. The following are examples of prolamins : — Gliadin from the seeds of wheat and rye. Hordein from the seeds of barley. Zein from the seeds of maize. < Albuminoids, etc . — The remaining simple proteins, albuminoids, his- tones, and protamines, are not found to occur in plants. 210. Conjugated Proteins. — Nucleoproteins. These bodies, called also nucleins, occur in the cells of animals and plants. Thus yeast yields a body represented, according to Miescher, by the formula C29H49N9P3022* This substance contains phosphorus in considerable quantity (9*59 per cent.), and is extremely resistant to the action of pepsin. Nucleoproteins may be regarded as compounds of nucleic acid with the proteins, which latter have H 98 THE TECHNOLOGY OF BREAD-MAKING. been shown to have basic properties. Nucleic acid, in turn, is viewed as a compound of albumin with phosphoric acid. Nucleoproteins are found in the protein constituents of wheat germ. Glycoproteins. — These bodies are proteins, containing either a carbo- hydrate or carbohydrate generating group within their molecule. There is, however, no definite evidence of the occurrence of glycoproteins in plants. Phosphoproteins . — Egg yolk contains a protein of the globulin type, of viiich phosphorus is an essential ingredient, and to which the name of vitellin has been given. It has been assumed that certain vegetable proteins are also of this class ; but vitellin may be repeatedly redissolved and re- precipitated without losing its phosphorus, whereas vegetable proteins con- taining phosphorus are thereby completely freed from that element. The conclusion is that the existence of true vegetable phosphoproteins has not as yet been proved. Hcemoglobins, etc . — It is doubtful whether any haemoglobins have been obtained from plants, while lecithoproteins are also probably absent from their constituents. 211. Derived Proteins. — Primary Protein Derivatives. Substantially, by the action of dilute acids and alkalies, the vegetable proteins undergo similar changes to those of animal origin when treated in a like manner. The derived proteins are the bodies already described as Class 3 of animal proteins. The proteans and metaproteins do not need description as a part of the present work. Coagulated proteins . — Many of the proteins possess the property of coagu- lation by heat, especially in the presence of a small quantity of free acid. This holds good much more with those of animal origin, for the correspond- ing seed proteins are in most cases only imperfectly coagulated by heating their solutions even to boiling. Thus leucosin from wheat, when obtained in solution by the extraction of wheat flour with water, is partly coagulated at a temperature of 52° C., but is not entirely so changed even at the boihng point. Secondary Protein Derivatives. — Small quantities of proteoses are found in seeds, but it is difficult to say whether these existed as such in the seeds, or have been produced by changes which have occurred during the processes involved in their separation. Present evidence is not sufficient to exclude the possibility of such changes, and therefore to demonstrate their existence as original components of the seeds. The same difficulties exist in the way of deciding whether or not pep- tones occur in plants. They may be formed from vegetable proteins by boiling with dilute mineral acids, or treatment with gastric or pancreatic juices. Animal proteins are, as a rule, more easily peptonised than those of vegetable origin ; thus papain, a vegetable enzyme, converts animal proteins into peptones, but carries the change of vegetable proteins no further than proteoses. 212. Albuminoids. — ^With the proposal, not universally adopted, to restrict this term to a series of bodies outside the protein group, it will be well to briefly state the character of albuminoids in this more restricted sense. The tendons of animals contain a body known as “ collagen,'" which is insoluble in water. By the action of dilute acids or boiling water, colla- gen is transformed into gelatin : the process is one of hydration, represented, according to Hofmeister, by the following equation : — Ci02Hi49N3iO28 Collagen. + H2O Water. C102H151N31O: Gelatin. 31 ^ 29 * THE PROTEINS. 99 The albuminoids, as thus classified, differ from the proteins in that they contain no sulphur. Gelatin is insoluble in cold water, but dissolves in hot water, gelatinising, or forming a jelly, on cooling. 213. Proteins of Wheat. — It is a fact too familiar to need experimental demonstration, that the white of egg coagulates on being heated ; but it will be found on further experiment, as may in fact be gathered from the preceding description, that if the white of egg be shaken up with consider- able quantities of water and then heated, the albumin separates out in coagulated flocks. Similarly on making a cold aqueous infusion of flour, or, still better, of the germ of wheat, and then filtering the solution until per- fectly clear, a liquid is obtained which, on being raised to the boiling point, throws down abundant flocks of albumin and globulin. The coagulated protein thus obtained is as white and pure in appearance as that from tlie white of egg, and is closely allied to that of mixtures of albumin and globulin of animal origin. While the egg albumin always occurs in an alkaline liquid, that of vegetables is always found either in acid or neutral liquids. Further, every miller and baker knows that flour, on being moistened, forms a stiff, tenacious paste or dough ; he also knows that the flour of wheat is distinguished in a remarkable manner from other flours by this character ; for oatmeal, when similarly treated, simply produces a damp mass, having little or no tenacity. On kneading a mass of wheaten dough, enclosed within a piece of muslin, vith water, until the starch is separated, there remains behind a greyish -white sticky elastic mass, to which the name of “ crude gluten is applied. This substance consists of the insoluble proteins of the wheat, together with portions of the ash, carbohydrates, and oily matter. Although this gluten, when in the flour, existed as a powder, yet, on the addition of water, it thus swells up into a tough mass. Gluten is practically insoluble in water, and without taste ; on being dried by ex- posure to the heat of the hot-water oven, it changes into a hard horny mass. Gluten which has been thus moistened with water, provided it is dried at a low temperature, swells up again on being wetted, although not usually to such a tough mass as when first extracted. Osborne, with whom has been associ- ated a number of other chemists, has for some years been engaged in a sys- tematic investigation of the vegetable proteins ; in 1893 he, in association with Voorhees, communicated to the American Chemical Journal an article of great importance on “ The Proteids [Proteins] of the Wheat Kernel.” This article contains a historical resume of the work previously done on these compounds, and also includes the results of their own elaborate investigations on wheat proteins, conducted on the lines of the most recent knowledge of the con- stitution of proteins generally. The following description is very largely based on Osborne and Voorhees’ article, which is still the most authoritative exposition of the properties of the wheat proteins. It is, in fact, not too much to say that science generally is indebted to Osborne for most of the work done on the vegetable proteins during the last twenty years. 214. Earlier Researches. — ^After recounting the results of the researches of Taddei, Berzelius, Mulder, Gunnsberg, and others, Ritthausen’s conclu- sions are mentioned, in which that chemist recognised in 1872 that wheat contains five protein bodies, to which he gave the names of gluten casein, gluten fibrin, plant gelatin or gliadin, mucedin, and albumin. He expressed a doubt as to the presence of albumin, as what was viewed as this body might possibly be a mixture of mucedin and gliadin. In 1880, Weyl and Bischoff published the view that the protein matter of wheat is principally a myosin-like globulin, which they call vegetable myosin, and, if this view be correct, they further assume that it is from this 100 THE TECHNOLOGY OF BREAD-MAKING. substance that gluten is derived, other proteins only being present in small quantity. They extracted flour with a 15 per cent, salt solution, and found that the residue yielded no gluten ; they consequently assumed that gluten is formed from myosin as a result of a ferment action similarly to the forma- tion of blood-fibrin from fibrinogen. No ferment possessing such properties could, however, be detected. Large quantities of sodium chloride and other salts prevent the formation of gluten in the same way as these salts also prevent the formation of fibrin. On first heating flour with alcohol, they found that subsequently no gluten could be obtained on washing, and so assumed that the myosin had been coagulated. Also, on warming flour for from 48 to 96 hours, keeping the temperature below 60° C., the coagula- tion point of myosin, and then adding a little unwarmed flour and extracting gluten from the mixture, no gluten is obtained beyond that present in the added flour, showing in Weyl and Bischoff ’s opinion that the gluten-forming substance had suffered coagulation. Martin in 1886 examined gluten by extraction with alcohol— he found but one protein substance so extracted. This body is soluble in hot water, but is insoluble in cold, and so is insoluble phyt-albumose. The residue insoluble in alcohol is uncoagulated protein, soluble in dilute acids and alkalies ; this he terms gluten-fibrin. The insoluble phyt-albumose is not present as such in flour, as direct extraction of the meal with 75 per cent, alcohol removes no protein. Martin concluded that the insoluble phyt- albumose is formed from the soluble by the action of water, the gluten- fibrin being formed by a similar action of water on the globulin, that is, conversion into an albuminate. The albuminate and insoluble phyt-albumose together constitute gluten. Johannsen, 1889, combats the ferment theory of the production of gluten. He found that a normal dough was obtained by grinding dried gluten and mixing with starch, and also by mixing moist gluten with starch. 215. Osborne and Voorhees’ Experiments, Wheats used. — One of these was a Minnesota spring wheat, Scotch Fife, milled under chemical super- vision into “ patent '' flour from finest and purest middlings, and “ straights from the coarser middlings. The “ shorts ” (red-dog ? ), chiefly composed of inner portions of the bran, with adhering portions of the endosperm, was also examined. Samples of whole wheat flour were prepared direct from the wheat by grinding in the laboratory when required. A variety of winter wheat, known as “ Fultz,” was also examined, but only as whole wheat hour. Preliminary investigations showed that all these different hours- yielded protein matter to — • Diluted alcohol. Water, 10 per cent, sodium chloride solution. And after complete and successive extractions with these reagents, to dilute potash water. The bodies extracted by these various reagents will be examined separ- ately. 216. Proteins Soluble in Water.— In the course of some preliminary experiments, £00 grams of spring wheat straight hour were mixed with 800 c.c. of distilled water. No coherent gluten formed, the undissolved hour settling down as a non-coherent mass. After a few hours’ digestion the solution was hltered ; the filtrate was straw-yellow in colour, becoming red-brown on standing, and had a venj slight acid reaction. Saturation with ammonium sulphate gave a bulky precipitate, which contracted on standing, showing the solution to contain but little protein matter. After 24 hours this precipitate was completely soluble in water. THE PROTEINS. 101 giving no evidence of the formation of so-called albuminates. Saturation with sodium chloride gave a small precipitate. Acetic acid in the cold gave no precipitate until sodium chloride was added. On slowly heating, the solution gave a turbidity at 48° C., and a floccu- lent coagulation at 52°. After heating to 65° for some time and filtering, the solution became turbid again at 73°, flocks forming in very small amount at 82°. Heating to boiling caused no further separation ; but the addition of a little acetic acid and sodium chloride gave a small precipitate. The body coagulating at 52° formed the greater part of the protein in solution. The complete coagulation of this required a temperature of 65°, but was greatly facilitated by the addition of sodium chloride. Further experiments showed that extraction of the flour with 10 per cent, salt (sodium chloride) solution yielded the same proteins, so that the subsequent examination of the water-soluble substances was confined to extracts originally made with 10 per cent, salt solution after separation of the globulins by dialysis. Again, 4000 grams of straight flour were treated with 8 litres of 10 per cent, brine, allowed to subside over night, and the supernatant liquid filtered off. Another 2 litres of the brine were added to the residue, which was stirred up, allowed to settle, and again filtered. The filtrate was saturated with ammonium sulphate as rapidly as collected. The precipitate thus procured was filtered and redissolved in 10 per cent, brine, filtered clear, and dialysed until the chloride had disappeared. This resulted in the pre- cipitation of a globulin, which was filtered off, and the solution again dialysed for 14 days, but with no further production of globulin. The globulin-free solution was next examined by slowly heating a por . tion — turbidity occurred at 48°, flocks separating at 55°. After heating at 65°, the coagulum was filtered off. Further heating resulted in a minute amount of coagulum being formed at 80° : after filtering, there was no further precipitate on boiling, and nothing was obtained by adding a little salt and acetic acid. On adding 20 per cent, salt solution and a little acetic acid to the original solution, a precipitate was caused ; another portion was first heated to 65°, and a third to 95°, and filtered before adding the salt solution and acetic acid. The second gave less, and the third least precipi- tate. The filtrate from the first of these portions, when neutralised and boiled, gave no precipitate, showing that, as was to be expected, the separa- tion of albumin by precipitation with salt and acid was complete. This globulin-free solution gave a precipitate on saturation with sodium chloride, the filtrate became flocculent at 56°, with no further precipitate on further heating, showing that the higher coagulating protein had been thus removed. Treatment of the globulin-free solution with nitric acid yielded a precipitate, a portion of which dissolved on heating, the rest re- maining insoluble : after filtration, the filtrate deposited a precipitate on cooling, which again dissolved on re-application of heat. The filtrate from the salt and acid precipitate did not give this reaction, which is characteristic of certain proteoses, and shows that the salt and acid precipitate contains a proteose, together with the albumins. Three distinct protein substances are thus recognised wFich are soluble in pure water ; two coagulable, one at a higher temperature than the other, and presumably both albumins and a proteose. To make sure that the body, which was apparently an albumin, was not a myosin-like globulin held in solution by the salts naturally present in river water used for dialysis, a strong aqueous solution of winter wheat meal was dialysed into distilled water in the outer vessel. The solution still coagu- lated at 54°, and contained in 250 c.c. only 0*0008 gram of mineral matter, proving the substance was an albumin. 102 THE TECHNOLOGY OF BREAD-MAKING. 217. Albumins.— The remainder of the globulin-free solution, after making the foregoing tests, was heated to 61°, the precipitate filtered, washed with water, alcohol, absolute alcohol, and ether, dried over sulphuric acid, and heated to 110° ; this was called Preparation 1. A duplicate lot was prepared in the same way, and yielded 64 grams from 10,000 grams of flour ; this was called Preparation 2. The filtrate from Preparation 2 was further heated to 75°, and the small amount of precipitate washed A^itli alcohol and dried as before ; this was called Preparation 3. Another preparation was made on the same flour by extracting with 10 per cent, brine, and dialysing at once without precipitation by ammonium sulphate. After the separation of the globulins, the albumins were precipi- tated by at once raising the temperature to 90° ; this, after drying, con- stituted the Preparation No. 4. Another preparation was made on the spring wheat “ shorts, by ex- traction with 10 per cent, salt solution, treatment with ammonium sulphate, dialysis, coagulating albumin at 65°, and drying ; this was Preparation 5. These substances gave on analysis the following results : Analyses of Coaoulated Wheat Albumin. 1 1 1 _l 3 4 1 5 i Average. Carbon 53*27 53*06 53*02 52*71 53*02 Hydrogen 6*83 '■ 6*82 • — 6*87 , 6*85 6*84 Nitrogen 16*95 17*01 16*94 16*26 16*83 16*80 Sulphur ' 1*27 1*30 i — 1*20 1*34 1*28 Oxygen 21*68 ' 21*81 ! — 22*65 1 22*27 , 22*06 1 100*00 . 100*00 — ! • 100-00 100*00 ‘ 100*00 ! These figures agree very closely, except that the nitrogen in No. 4 is low : as four determinations give concordant results, Osborne and Voor- hees consider it possible that some of the nitrogen may be lost at the higher temperature. 218. Proteoses. — As already stated, there are found in the solution after separating the globulins by dialysis, and the albumins by heating, small quantities of one or more proteoses which are almost wholly precipitated by saturation with sodium chloride. On concentrating the filtered solution, after the removal of albumins by heat, a coagulum gradually develops, which must be derived from the proteose-like protein still remaining in solution before concentration. This body gave on analysis the following figures : . . 51 *86 Carbon Hydrogen . . 6*82 1 ^ o o Nitrogen . . 1 / *o2i Sulphur) . . 24 00 Oxygen ) 100-00 The small quantity of proteose still remaining after removal of the coagulum was not separated for analysis. In analyses quoted later, para- graph 233, the amount of this proteose is seen to be as much or more than tliat of the coagulum. THE PROTEINS. 103 219. Globulin. — The extraction of this body has already been referred to : in a direct experiment for the preparation of globulin, 10,000 grams of “ straight ” flour were extracted with 34 litres of 10 per cent, salt solution, stirred and allowed to stand over night. This was filtered, precipitated by saturation with ammonium sulphate, filtered and again dissolved in 10 per cent, brine. The solution produced was exceedingly viscid, and filtered vdth extreme difficulty ; this was placed in a dialyser and left in a stream of running water until the chlorides were removed. The globulin gradually separated out in minute particles of spheroidal form. The precipitate was filtered, washed with water, alcohol, and ether, dried over sulphuric acid and then weighed 5*8 grams. Globulin, thus prepared, dissolves in 10 per cent, salt solution, from which it is precipitated by the addition of water Saturation with sodium chloride gives no precipitate, but saturation with magnesium sulphate, or ammonium sulphate, completely precipitates the globulin. The solution in 10 per cent, brine gives, on slow heating, a very slight turbidity at 87°, which increases slightly up to 99°. Dried at 110°, this globulin constituted Preparation 8. A preparation was also made in the same way, except that the precipita- tion with ammonium sulphate was omitted. Again the solution was remark- ably viscid, a property possibly due to the presence of gum, for the pure solution of globulin in 10 per cent, brine showed no trace of it, neither did an aqueous solution of the flour. On dissolving up the globulin obtained by dialysis in 10 per cent, salt solution, a residue remains, consisting of aii “ albuminate ’’ derived from the globulin. This globulin constituted Preparation 9. The globulin was also extracted from the “ shorts,'’ and its total quan- tity amounted to nearly twice as much as was similarly obtained from a like quantity of flour. This globulin was Preparation 10. The globulins gave on analysis the following results : — Analyses of Wheat Globulins. ; ■ ' s ___ . _ Jv . 9 10 Average. j Carbon . . 51-07 51-01 51-00 51-03 Hydrogen 6-75 6-97 6-83 6-85 Nitrogen . . .. ; 18-27 18-48 18-26 18-39 ; Sulphur . . 23-91 ! / 0-71 0-66 0-69 i , Oxygen . . 1 t 22-83 23-25 23-04 1 i i i 100-00 1 i 1 100-00 100-00 100-00 , In contradistinction to the views held by Weyl and Bischoff, and Martin, Osborne and Voorhees have only found in extracts of wheat meal, either spring or winter wheat, the one globulin just described ; which in proper- ties and composition closely resembles those globulins found in other seeds. 220. Protein Soluble in Dilute Alcohol ; Gliadin. — ^Whether wheat flour be extracted direct with dilute alcohol, or after treatment with 10 per cent, salt solution, a considerable amount of protein is obtained. The same is the case if the previously extracted gluten be subjected to alcohol extraction. Extracts were made by aleohol under all these conditions, and subjected to repeated fractional precipitations, in order to learn whether a single protein body or a mixture had been obtained. 104 THE TECHNOLOGY OF BREAD-MAKING. 221. Direct Alcoholic Extraction. — In direct treatment with alcohol 5000 grams of “ straight ’’ flour were extracted with 10 litres of alcohol, 0*90 specific gravity, and allowed to soak over night. The mixture was then stirred, allowed to settle, and the supernatant liquid poured off. Three litres more of alcohol of the same strength were added, and presumably stirred in ; after standing, the clear liquid was poured off, and the residue put in a screw press and squeezed nearly dry. The whole of the liquid thus obtained was mixed, and constituted “ Extract 1."" The residue was again treated with 4 litres of 0*90 alcohol, and once more pressed nearly dry ; this liquid was “ Extract 2.” The same process was twice more repeated, and the two extracts mixed, which gave “ Extract 3.’" Each of the three ex- tracts was filtered clear, and concentrated separately to one-third its volume, and after cooling decanted from the very glutinous viscid mass which had separated. This precipitated mass was in each case dissolved in a small amount of hot alcohol, sp. gr. 0*90, and the solution allowed to cool over night : most of the substance separated on cooling, and the liquid w'as decanted from it. The solutions were treated with a quantity of distilled water and a little sodium chloride added, the protein was thus precipitated, washed with water, absolute alcohol, and ether, and dried. The residue was subjected to a series of fractional precipitations based on the principle of partially dissolving with alcohol of 0*820 sp. gr., and precipitating from the solution by the addition of small quantities of sodium chloride solution, which precipitate was washed, dehydrated with absolute alcohol, digested with ether, and dried over sulphuric acid. A portion of the principal frac- tion was again divided by solution in 250 c.c. of 0*90 alcohol, and partial precipitation by pouring the solution into 800 c.c. of absolute alcohol ; precipitate and solution were again treated separately. As the result of a series of fractional precipitations, altogether thirteen fractions were prepared and then analysed. These constituted Preparations II to 23. The results of the whole series are given by Osborne and Voorhees, but five of the fractions are discarded from the final comparison, because of their being impure, for obvious reasons. Some, for example, contain fat, while others have con- centrated in them the solid matter which in a series of filtrations has passed through the filter papers. Subjoined is given the results of these various analyses, and the weight of each fraction which was obtained : — Analyses of “ Fractions ” of the Wheat Protein obtained by Direct Extraction with Dilute Alcohol. 1 15 16 17 1 19 21 24 25 26 Carbon 52*52 1 52*77 52*67 52*55 52*74 52*82 52*33 52*38 Hydrogen. . 6*78 6*78 6>70 6-85 : 6*77 6*81 — 6*91 7*13 Nitrogen . . 17*64 17*77 17*66 17*94 ' 17*62 17*67 17*69 17*70 17*82 Sulphur . . 1*08 1*26 1*22 1*21 1 1*23 j 1*11 ) 23*06 22*67 Oxygen . . 21*98 21*42 j ' 21*75 L 21*45 21*64 ! 21*57 1 100*00 100*00 100*00 100*00 100*00 1 100*00 100*00 100*00 Weight of| fraction in ■ ' gram j 12*40 8*60 32*26 5*34 17*43 i ' 63*0 ; — — — Nos. 24, 25, 26 are fractional re-precipitations of fraction No. 21. THE PROTEINS. 105 A study of this series of analyses shows that the whole of the fractions -are in remarkable agreement, and that no fractional separation of the ex- tracted protein has been effected. For example, Nos. 15 and 16, which are aqueous solutions, have the same composition as those from solution in '0*8£0 alcohol, and also as the residue remaining after treatment with these reagents. Osborne and Voorhees draw the conclusion that it may be safely eoncluded that wheat contains but one protein soluble in dilute alcohol. The total amount of protein contained in the whole of these preparations is 207*83 grams, being equal to 4*16 per cent, of the flour. 222. Alcoholic Extraction after Salt Solution Extraction. — ^For this pur- pose 4000 grams of “ straight '' flour were taken, extracted with 10 per cent, salt solution so long as anything was removed, and then the residue squeezed -as dry as possible in a screw-press. This residue was then treated with alcohol of such a strength as to yield with the water retained in the flour as nearly as possible a solution containing 75 per cent, of alcohol. Digestion with this solvent was continued for two days ; the extract was squeezed in -a press, and the process repeated three times, giving altogether four extracts. These were concentrated to small bulk, and the solution decanted from the separated mass, which was washed with distilled water, re-precipitated by sodium chloride, washed with absolute alcohol, digested with ether, and ■dried over sulphuric acid. The precipitates obtained from the water wash- ings by adding salt were treated in the same way. The total weight of these preparations was 157*45 grams, equal to 3*94 per cent, of flour, as against 4*16 per cent, obtained by direct extraction, showing that the dilute alcohol extract is different and distinct from the proteins soluble in water. These constituted Preparations 27-31. The following table gives the result of their analyses : — Analyses op Fractions ” of Wheat Protein obtained by Extraction WITH Dilute Alcohol after Sodium Chloride Extraction. 27 28 29 30 31 Carbon . . 52-69 52-72 52-71 52-65 Hydrogen . . . , i 6*84 6-86 6-81 6-83 Nitrogen. . . . . . | 17*73 17-89 17-75 17-08 17*79 Sulphur . . 1-02 0-95 1-10 — 1*08 Oxygen i i 21-72 1 21-58 21-63 — 21-65 Weight of fraction in| 100-00 82-0 100-00 57-0 100-00 11-3 1-35 100-00 5-8 grams . . . . . . ) Nos. 27-30 are the precipitates obtained from the four extracts ; No. 31 is obtained from the water washings of 27 and 28. \ The results of these analyses agree very closely among themselves, and also with the series obtained by direct alcoholic extraction. 223. Extraction of Gluten with Dilute Alcohol. — ^For the preparation of gluten, 2000 grams of “ straight flour were made into dough with distilled 106 THE TECHNOLOGY OF BREAD-MAKING. water at 20°, and then washed in a stream of river water at 5° C. When nearly the whole of the starch had thus been removed, the gluten was chopped fine and digested with alcohol of 0*90 sp. gr. at a temperature of about 20°. This extraction was repeated with fresh portions of alcohol of the same strength so long as anything was removed. The extracts were united, filtered clear, and evaporated down to one-fourth their original volume. This was allowed to stand over night, and the supernatant liquid decanted from the separated protein. This latter was then dehydrated with absolute alcohol. The original mother-liquor from which the protein had separated, and also the absolute alcohol used for dehydrating, Avere each precipitated by a small quantity of sodium-chloride solution. The three products were united, digested with absolute alcohol, and then with absolute ether. After drying over sulphuric acid, the Preparation'^No. 32 weighed 82*0 grams, and formed 4*10 per cent, of the flour taken. In order to determine whether this substance AA^as a single protein or a mixture of more than one, the pro- cess of fractional precipitation Avas again employed. Thirty grams of Pre- paration 32 Avere dissolved in 0*90 alcohol, concentrated to small volume, and then strong alcohol added till about half the substance taken had been precipitated. The precipitate was treated Avith absolute alcohol, dried over sulphuric acid, and found to AA^eigh 12 grams ; this constituted Pre- paration 33. The solution Avas precipitated AAith Avater, dehydrated and dried over sulphuric acid ; it Aveighed 16 grams, and Avas marked Preparation 34. These substances had the folloAAung composition : — Analyses of ‘‘ Fractions ” of the Wheat Protein obtained by Extraction of Gluten aahth Dilute Alcohol. t 32 1 33 1 3-4 : Carbon I 52-58 52-68 52-84 Hydrogen 6-67 6-78 1 7-18 Nitrogen 17-65 17-65 17-57 Sulphur 1-08 t 92*41 Oxygen 22-02 21-80 I) 100-00 100-00 100-00 i In this case also the analyses sIioav clearly that no separation into pro- teins of differing composition had thus been effected. 224. Extraction of “ Shorts ” with Dilute Alcohol. — In order to deter- mine Avhether the “ shorts ” or bran flour yielded the same body to dilute alcohol, 2000 grams AA'ere taken and subjected to much the same process of extraction as AAas flour, except that greater precautions Avere necessary in order to remove impurities. Taao Preparations, Nos. 36 and 37, were obtained, Avhich had the folloAving composition : — THE PROTEINS. 107 Analyses of Fractions of Wheat Protein obtained by Extraction of “ Shorts ” with Dilute Alcohol. 36 1 i 37 Carbon 52-85 52-74 Hydrogen 6-81 6-87 Nitrogen . . 17-48 17-67 Sulphur . . . . . . . . . . ) Oxygen . . . . . . . . . . j 22-86 22-72 100-00 100-00 A comparison of tliese figures with those which have preceded shows that the protein extracted from the bran has a similar composition to that obtained from the flour. 225. Extraction of Whole Wheat Meal with Dilute Alcohol. — ^In view of the fact that Ritthausen, and probably others, employed whole wheat meal in their investigations of the composition of wheat proteins, Osborne and Voorhees decided to make some experiments on wheat meals, in addition to those previously described. Accordingly, 1000 grams of freshly ground whole spring wheat meal were taken, made into a dough, and the gluten extracted. This was chopped fine, thoroughly extracted vith 0*90 alcohol, the extract concentrated, and the protein separated by cooling. This de- posit was dissolved as far as possible in dilute alcohol, and the insoluble substance washed with absolute alcohol, and ether, and dried over sulphuric acid. This was Preparation 38. The solution was precipitated with abso- lute alcohol, dried as usual, and constituted Preparation 39 ; the filtrate from this was concentrated to small volume, poured into absolute alcohol, and the precipitate washed and dried as before, giving Preparation 40. In a similar manner. Preparations were made from winter wheat meal ; the coagulated protein w as labelled 41, and that obtained by further diges- tion, 42. These had the following composition ; — Analyses of Wheat Proteins obtained by Extraction of Whole Wheat Meal whth Dilute Alcohol. Spring Wheat. 1 Winter Wheat. I i 38 39 40 41 42 : Carbon . . . . . . 52-90 ^ 52-89 53-16 52-82 1 52-68 Hydrogen . . . , 6-99 : 6-87 6-83 6-88 6-81 Nitrogen. . 17-52 18-06 17-75 17-55 17-63 Sulphur . . Oxygen . . 1-43 21-16 0-92 21-26 0-96 21-30 1 22-75 22-88 100-00 100-00 100-00 100-00 100-00 j 108 THE TECHNOLOGY OF BREAD-MAKING. Throughout the whole series there is no essential difference in composition, nor in physical properties ; nor was the protein altered in composition by solution in dilute caustic potash, and re-precipitation by an equivalent quantity of hydrochloric acid ; neither, so far as it could be observed, was its solubility altered. The composition of this protein, as obtained by averaging the preceding figures, is the following Carbon . . . . . . . . . . . . .. 52*72 Hydrogen 6*86 Nitrogen 17*66 Sulphur . . . . . . . . . . . . . . 1*14 Oxygen 21 *62 100*00 226. Properties of Protein extracted by Dilute Alcohol. — If this protein be dehydrated by absolute alcohol, and thoroughly dried over sulphuric acid, it forms a snow-white friable mass easily reduced to powder. When dried from weak alcohol or water, it forms an amorphous transparent sub- stance, closely resembling pure gelatin in appearance, being, however, rather more brittle than that body. In the cold, distilled water turns the substance sticky, and a part dissolves. As the water is warmed, the degree of solu- bility increases, and with boiling, a considerable quantity goes into solution. A portion of this is re-deposited on cooling. The solution in pure water is instantly precipitated by adding a very minute amount of sodium chloride. In abso- lute alcohol this protein is perfectly insoluble, but dissolves on the addition of water, being very soluble in 70 to 75 per cent, alcohol. From alcoholic solutions, minute quantities of salt readily precipitate the protein. Exceed- ingly dilute acids and alkalies readily dissolve this protein, which is again precipitated apparently unchanged in appearance and composition by neutralisation. This protein has been obtained in a more or less pure form by earlier observers ; Taddei first gave it the name of “ gliadin.’" Ritthausen and others assumed that it consisted of a mixture of two or more substances, to which the names of mucin or mucedin, and gliadin or vegetable gelatin, have been given. Among recent observers, Martin found in gluten only one protein soluble in dilute alcohol, to which he gaye the name of “ insoluble phyt-albumose,” but, curiously enough, stated that flour extracted direct vith 76 to 80 per cent, alcohol yielded no soluble protein. This is in direct opposition to the results of Osborne and Voorhees, and also, it may be added, to those of the authors of the present work, one of whom, prior to seeing Osborne and Voorhees’ paper, made a series of analyses of various flours, in which a direct gliadin estimation by alcohol was included. These results are given in Chapter XV, paragraph 438. Osborne and Voorhees adopt gliadin as the original and appropriate name for the vheat protein sclulle in dilute alcohol. They point out that gliadin is absolutely distinct in properties and composition from the other alcohol-soluble proteins, prolamins, obtained from the kernel of oats and maize. 227. Protein insoluble in Water, Saline Solutions, and Alcohol ; Clute- nin.— After treatment with the scriis of previously described solvents, a protein body remains in wheat flour and gluten, which is soluble only in dilute acids and alkalies. This protein being especially characteristic of gluten, Osborne and Voorhees have given it the name Glutenin. In the following accounts of extraction of glutenin, it is throughout THE PROTEINS. 109 understood that the separations are made on flour or meal which has pre- viously been exhausted with one or more of the following solvents : Water, 10 per cent, salt solution, and dilute alcohol. 228. Extraction of Glutenin from “ Straight Flour after Treatment with Brine and Dilute Alcohol. — -After completely exhausting 4000 grams of straight flour successively with 10 per cent, brine and 0*90 sp. gr. alcohol, the residue was extracted twice with 0*1 per cent, potash solution. The residual protein was soluble in this, and after standing three days at a tem- perature of 5°, with frequent stirring, the extract was Altered off and al- lowed to stand in a cold room until most of the finer solid impurities had subsided. The still turbid solution was then decanted and neutralised with 0*2 per cent, hydrochloric acid, thereby producing a precipitate which subsided rapidly, leaving a milky filtrate. This precipitate was redissolved in the dilute potash, allow^ed to stand in order to deposit impurities, and again precipitated with 0*2 per cent, hydrochloric acid. The protein was w^ashed with w^ater, dilute alcohol, absolute alcohol, and ether. This pre- paration ’svas found to be far from pure, and accordingly a portion of it was again dissolved in 0 *2 per cent, potash, and repeatedly filtered through very dense filter paper till perfectly clear. As this filtration proceeded very slowly the operation was conducted in a refrigerator at a temperature near 0°C. Tw'o successive portions of the filtrate obtained were reprecipitated with 0 *2 per cent, hydrochloric acid, w^ashed with water, alcohol, ether, and dried over sulphuric acid, and then at 110°. These gave Preparations 45 and 46. It was found absolutely necessary to Alter the potash solution perfectly clear, as otherwise considerable amounts of non-nitrogenous matter are subsequently carried dowm with the precipitate. 229. Extraction of Glutenin after Treatment of Dough with Water and Exhaustion with Dilute Alcohol. — ^A dough was made with 2000 grams of spring wheat “ straight ” flour and distilled water ; this was washed with river water till freed so far as possible from starch. The gluten was ex- hausted with 75 per cent, alcohol, and the insoluble residue dissolved in 0*15 per cent, potash solution, and allowed to stand in a cold room for 48 hours. The solution w^as decanted, precipitated with dilute hydrochloric acid, washed thoroughly with water, absolute alcohol, and ether. It w^as then again dissolved in 0*1 per cent, potash, allow ed to stand over night. Altered till perfectly clear, and a part of the filtrate precipitated by neu- tralising with 0*2 per cent, hydrochloric acid. This precipitate w^as dried as usual, and constituted Preparation 48. Another lot of gluten w as prepared in the same w ay from 1000 grams of “ straight ” flour, extracted with alcohol and then dissolved in potash water. After standing, this was precipitated by adding acetic acid to slightly acid reaction. The precipitate Avas Avashed AAltli AA^ater, alcohol, and ether, and again dissolved in potash AA'ater, reprecipitated aaIUi hydrochloric acid, and again AA^ashed and dried as usual over sulphuric acid. A pure AAliite light mass w^as obtained, wliich was marked Preparation 51. In order to determine Avhether the protein lost any nitrogen by pro- longed solution in potash w^ater, another lot of gluten AA^as similarly treated, and the potash solution kept in an ice-chest for £0 hours, and then precipi- tated and treated in the usual manner. This constituted Preparation 52, and had evidently lost but exceedingly little nitrogen. 230. Extraction of Glutenin after Direct Exhaustion of Flour with Alcohol, Water Treatment omitted. — ^Another preparation was made by extracting 200 grams of spring patent flour with large quantities of alcohol of 0*90 110 THE TECHNOLOGY OF BREAD-MAKING. sp. gr., then washing the flour with absolute alcohol and drying and air-drying Tlie dr}^ flour was then made into a dough, which possessed considerable coherence, showing that the protein insoluble in alcohol has an important function in dough production. The dough was washed on a hair-sieve under a stream of water, but yielded no coherent gluten. The washings were allowed to settle, and the sediment treated with 0*2 per cent, potash. After standing, the supernatant liquid was decanted, precipitated with dilute hydrochloric acid, and the precipitate allowed to settle. It was then again dissolved in dilute potash, filtered perfectly clear while in the ice-chest, reprecipitated, and washed and dried in the usual manner. This constituted Preparation 56. Another experiment was made by direct alcohol treatment, in which 1000 grams of “ straight '' flour were exhausted with 0-90 alcohol, and the residue squeezed in a screw-press. This was then extracted with 0*2 per cent, potash, but filtration was impossible owing to the gummy nature of the liquid. An equal volume of alcohol, sp. gr. 0*820, was then added, and after long standing a comparatively clear yellow solution was syphoned off and filtered clear. This was precipitated with hydrochloric acid, and the precipitate filtered off and again dissolved in potash, filtered perfectly clear, reprecipitated, washed with water, dilute and then absolute alcohol, and ether. This yielded Preparation 57, the analysis of which shows that the same protein is extracted by potash water from the flour which has not been in contact with water as was obtained in other experiments. 231. Extraction of Glutenin from Gluten of Whole Wheat Flour. — ^A dough was made from 1000 grams of whole spring wheat meal, washed till free from starch, and the gluten exhausted with dilute alcohol. The residue was dissolved in dilute potash, allowed to stand, decanted, reprecipitated, and the precipitate washed with water, dilute alcohol, absolute alcohol, and ether, and then re-dissolved in 0 *2 per cent, potash water. This was filtered perfectly clear, and precipitated and treated in the usual way. The dry protein was Preparation 58. A preparation was made in the same manner from whole winter wheat meal, which constituted Preparation 60. In the following table, analyses are given of the whole of the glutenin preparations which have been des- cribed. Analyses of Protein of Wheat soluble only in Dilute Acids AND Alkalies — Glutenin. 45 46 i 51 52 56 57 58 60 Carbon 52-29 r 52-32 52-54 52-38 52-19 5219 52*03 Hydrogen. . 6-61 — 6-82 6-85 6-81 — 6-92 6-93 6*83 Nitrogen . . 17-41 17-33 17-61 17*46 17*59 17-20 17-56 17*45 17*48 Sulphur . . Oxygen . . 0-94 22-75 — ): 23-25 ( 107 (22-08 1-24 21-98 — ) — i' 23-33 23*43 23*66 • 100-00 — 100-00 lOO-OOi 100-00 — 100-00 100-00^ 100*00 i 232. Properties of Glutenin. — ^The characteristic reactions of glutenin owing to its comparative insolubility, are not numerous. A minute quantity THE PROTEINS. Ill is dissolved by cold water, and more on slightly warming. Diluted alcohol also dissolves a small quantity of protein in the cold, and a larger quantity on boiling, which again precipitates as the liquid cools. It is just possible that this is due to the presence of traces of gliadin, but in face of the very oareful exhaustion by alcohol previous to preparation of glutenin, it is more probable that glutenin itself is slightly soluble both in warm alcohol and warm water. When freshly precipitated and hydrated, glutenin is soluble in Od per cent, potash solution, and 0*2 per cent, hydrochloric acid. In this condition it is also soluble in the slightest excess of sodium carbonate solution or am- monia. After drying over sulphuric acid, it becomes rather less soluble in all these reagents. On comparing the analyses of gliadin and glutenin, a very close agreement is observed. It is well known that many proteins pass readily into conditions in which their solubility is changed without any alteration in their composition, capable of detection by analysis. Osborne and Voorhees therefore concluded that gluten was made uj3 of two forms of the same protein, one being soluble in cold dilute alcohol, and the other not soluble. But Osborne, who has since studied the products of their com- plete hydrolysis, finds that gliadin differs sharply from glutenin in yielding no glycine and no lysine ; it also gives nearly twice as much proline as glu- tenin (Armstrong, Su'p'plement, Jour. Board of Agric., June, 1910, p. 48.) It can scarcely, therefore, be maintained that these proteins have a common origin. 233. Amount of the various Proteins contained in Wheat. — ^The per- centage of each protein present in whole- wheat meal was determined by an analysis on 1000 grams of meal from spring and winter wheats respectively. The following is an outline of the analytic method adopted, which was the same in each case. To 1000 grams of the fine meal were added 4000 c.c. of 10 per cent, salt solution, and the extract filtered ; 2500 c.c. of clear extract were obtained from the spring meal, and 2600 from the winter wheat meal. As 100 c.c. of solution were used to each 25 grams of flour, 2500 c.c. = extract from 625 grams spring meal, and 2600 c.c. = ,, ,, 650 ,, winter meal. The extracts were dialysed for five days, at the end of which time they were free from chloride. The precipitated globulin was filtered, washed with distilled water, alcohol, absolute alcohol, and ether, and dried at 110°. The following weights were obtained : — 3*8398 grams = 0*624 per cent, globulin in spring wheat. 3*9265 ,, =0*625 ,, ,, ,, winter ,, The filtrates from the globulin were heated to 65°, and the coagula formed at that temperature removed by filtration, washed as usual, dried at 110°, and weighed with the following results : — 1*9714 grams = 0*315 per cent. No. 1 albumin in spring wheat. 1*9614 ,, =0*302 ,, ,, ,, winter ,, The filtrates from these were heated to boiling, and the second coagula similarly treated. The weights obtained were : — 0*4743 grams =0*076 per cent. No. 2 albumin in spring wheat. 0*3680 ,, =0*057 ,, ,, ,, winter ,, The filtrates were evaporated nearly to dryness, and two crops of coagu- lated protein removed, washed, dried, and weighed — together they amounted to : — 1*6886 grams = 0*269 per cent, coagulum in spring wheat. 1*4516 ,, =0*223 ,, ,, ,, winter ,, The filtrates from the coagula were next again evaporated to a syrup and, as no insoluble matter separated, were precipitated by pouring into 112 THE TECHNOLOGY OF BREAD-MAKING. strong alcohol, the precipitates were washed, dissolved in water and repre- cipitated, washed with absolute alcohol and ether, and dried at 110°. They were evidently very impure, and the amount of protein present in each was estimated by determining the nitrogen and multiplying by 6 ‘25. They gave in this way the following results : — 1*3297 grams = 0*213 per cent, proteose and peptone in spring wheat. 2*8083 ,, =0*432 ,, ,, ,, ,, winter „ Collecting these figures, the sodium-chloride solution contained the following amounts of protein matter : — Globulin Two Albumins together Coagulum . . Proteosf^ SpriQg Wh3at. 0*624 per cent. 0*391 0*269 0*213 Winter Wheat. 0*625 per cent. 0*359 ?> 0*223 0*432 Total 1*497 „ 1*639 The remainder of the protein matter constitutes the gluten, and was determined in the following manner — 200 grams of each meal were made into a dough and washed free from starch. The wet gluten, freed from adhering moisture, was then weighed, and exactly one-half dried at 110° to constant weight. Spring wheat yielded 12*685 per cent, dry gluten. Winter ,, ,, 11*858 ,, ,, „ The other half of the gluten was cut up fine, and extracted with alcohol of 0*90 sp. gr. The extract was concentrated, and the precipitated protein extracted with ether and dried at 110°. Reckoned on the whole meal, Spring wheat gluten yielded 4*3379 per cent, gliadin. Winter ,, ,, 4*2454 ,, ,, The residues, after exhaustion with alcohol, were then dried at 110° and weighed. Reckoned on the whole meal. Spring wheat gluten yielded 7*800 per cent, matter insoluble in alcohol. Winter ,, „ „ 7*504 Nitrogen determinations were then made on the following bodies — the- whole meal insoluble alcohol residues, .dried gluten, and the sediments of the water used for washing out gluten, after being washed with strong alcohol, dried and weighed. The following is the tabulated result of the various- determinations : — Proximate Analysis of Proteins of Wheat. Total nitrogen in the meal . . Spring. 1*950 per cent. Winter. 1*940 per cent. Total gluten in the meal 12*685 11*858 Part of gluten insoluble in alcohol . . 7*800 7*504 Per cent, of nitrogen in gluten 12*010 12*000 Total nitrogen in gluten in per cent, of hour 1*5222 „ 1*4230 „ Total nitrogen in residue of gluten in- soluble in alcohol . . 0*8245 „ 0*7346 „ Total nitrogen extracted by alcohol . . 0*6977 „ 0*6884 „ Gliadin (Nx5*68, assuming 17*60 per cent, of N in gliadin) 3*9630 „ 3*9100 ., Gliadin by direct weighing . . 4*3379 „ 4*2454 „ Nitrogen in sediment from washing gluten 0*2239 „ 0*1552 ,, THE PROTEINS. 113 i 1 Spring Wheat. Xitiogen. Protein. Wi.NTER Wheat. Xitrogen. Protein. ! Glutenin . . 0-8245 x5-68= 4*683 0*7346x5*68= 4*173 1 Gliadin 0*6977x5*68=: 3*963 0*6884x5*68= 3*910 j Globulin . . . . 0*1148 = 0*624 0*1148 = 0*625 ! Albumin . . 0*6057 = 0*391 0*0603 = 0*359 Coagulum . . 0*0453 = 0*269 0*0379 = 0*223 1 Proteose . . 0*0341 = 0*213 0*0791 = 0*432 From Water Wash- ings of Gluten. . 0*2239x5*68= 1*272 0*1552x5*68= 0*881 Total 2*0050 11*415 , 1*8703 10*603 Meal . . 2T0 x5-68 = 1193 ; 1-94 x5-68 = :10 96 Inspection of the above figures shows that the gliadin by direct weighing agrees fairly well vdth that estimated from a nitrogen determination. The residue insoluble in alcohol is, however, very much more than the true glutenin : thus, in the spring wheat the insoluble residue weighed 7*80 per cent, of the meal, whereas the glutenin calculated from nitrogen amounted to only 4*683, leaving 3*117 of foreign matter in the residue insoluble in alcohol. The total protein agrees in each case very closely with the whole found by direct estimation on the meal. The same figures as those above given are quoted in a work recently written by Osborne (1609) as repre- senting the amounts of proteins contained in the grain of wheat. 234. The Formation of Gluten. — So far as is known, wheat is the only plant whose seeds contain proteins in such a form as to enable them to be separated in a coherent mass from the other constituents by washing with water. Osborne and Voorhees have examined very carefully the views promulgated on this point by previous observers ; prominent among these is the “ ferment ” hypothesis of Weyl and Bischoff, who, as previously stated, considered the proteins of wheat meal to consist principally of a globulin very similar in character to myosin, and which they therefore termed “ vegetable myosin.'' This they regarded as the mother-substance of gluten, which on the addition of water is changed by a ferment, hitherto unisolated, into gluten, “ as other proteins, if present at all, exist only in small amount " (Weyl and Bischoff). The exhaustive analyses previously quoted show that globulin and also gliadin form only about half the total ])rotein of the grain. Osborne and Voorhees point out that gliadin is ex- tracted in similar quantity from dry flour direct by alcohol, as is yielded after treatment with 10 per cent, sodium chloride solution, or by direct ex- traction of the previously washed out gluten. Weyl and Bischoff state that with the aid of a 15 per cent, salt solution the flour was extracted till no protein could be detected in the extract ; the residue of the meal kneaded with water then gave no gluten. “ If the globulin substance is extracted, no formation of gluten takes place.’* Osborne and Voorhees confirm this if the flour is stirred up with a large quantity of salt solution, and then extracted repeatedly with fresh quantities of the solution. But they say : “ If, however, wheat flour is mixed at first with just sufficient salt solution to make a firm dough, this dough may then be washed indefinitely with salt solution, and will yield gluten as well and as much as if washed with water alone." This statement alone is scarcely a sufficient disproof of Weyl and Bis- choff 's position. In a firm dough made with 15 per cent, salt solution, the quantity of salt will only amount to 5 per cent, of the dough. As nothing 114 THE TECHNOLOGY OF BREAD-MAKING. has been removed in the act of making dough, it may be reasonably claimed that this quantity of salt is insufficient to prevent the ferment performing its function, and thus producing gluten ; while further, the gluten once formed is able to withstand the action of the salt solution which is unable to decompose it. Osborne and Voorhees go on to state that “ when large quantities of salt solution are applied at once, the flour fails to unite to a coherent mass, and cannot afterwards be brought together.’' This action of salt solution in large quantities is explained by subsequent experiments, in which it is shown that such solution materially modifies the adhesive nature of gliadin. Weyl and Bischoff’s experiment, in which they extracted the flour mth 90 per cent, alcohol, is scarcely conclusive, because according to both h 3 rpo- theses this would result in the non-formation of gluten. In the one case globulin would be coagulated, and in the other gliadin would be removed, and so according to both reasoners no gluten could be produced. More recently, Martin has advanced a somewhat similar theory of gluten formation ; he finds one protein in gluten soluble in alcohol, and in hot water, but not in cold, which protein he calls an insoluble phyt-albumose. The gluten is termed by him “ gluten-fibrin.” Martin next inquires : Does flour contain gluten-fibrin ? Does it contain insoluble phyt-albumose ? He states that the first question cannot be answered directly, and that, if phyt-albumose originally existed in the flour, it should be extracted by 76-80 per cent, alcohol, which, however, extracts only fat. There is here direct conflict of experimental evidence, as the analyses previously quoted show that considerable quantities of a protein are thus extracted. Martin next points out that 10 per cent, sodium chloride solution extracts a large quantity of globulin of the myosin type and of albumose. Osborne and Voorhees consider that Martin has made the mistake of taking albumin for a myosin- like globulin, and, owing to the voluminous nature of the body when coagu- lated, has been misled as to its amount. Martin further looks upon the insoluble albumose as formed from the soluble, and that the globuhn is transformed into gluten-fibrin. That a body should be obtained from a solution of globulin, which gave the same reactions as gluten- fibrin, is not surprising, as so-called albuminates, having no characteristic reactions, are derived from nearly all globulins. Martin tabulates his theory as follows : — p _ I Gluten-fibrin — precursor, globulin. LUTEN I Insoluble albumose — ,, soluble albumose. Osborne and Voorhees cannot admit this theory, because it is founded on two erroneous observations : 1st, that 80 per cent, alcohol does not extract protein from flour ; 2nd, that at least one-half the protein of the seed is a myosin-like globulin. Osborne and Voorhees conclude that no ferment action is involved in the formation of gluten, and that it contains but two protein substances, glutenin and gliadin, and that these exist in the wheat kernel in the same form as in the gluten, except that in the latter they are combined with about thrice their weight of water. This opinion is based on the following reasons : — 1. Alcohol extracts the same gliadin in the same amount, whether applied directly to the flour, to the gluten, or to the flour previously ex- tracted with 10 per cent, sodium chloride solution. 2. Dilute potash solution extracts glutenin of uniform composition and properties from flour which has been extracted with alcohol, or with 10 per cent, sodium chloride solution and then with alcohol, as it extracts from gluten which has been exhausted with alcohol. Viewed as a refutation of the ferment theory, the weak point of this THE PROTEINS. 115 statement is that in order to prepare gliadin the flour is in all cases treated with water, as even the alcohol used contains water to the extent of 30 per cent, (although extraction with 70 per cent, alcohol is a condition the reverse of favourable to ferment action). The advocates of the ferment theory might adduce the fact that small quantities of ferment substance are capable of changing very large quantities of the body on which the^^ act, and further might suggest that the small quantity of globulin which is removed by treatment with sodium chloride solution is the ferment in question. It is well known that flour contains a diastase precipitated by alcohol, which presumably belongs to the albumins or globulins ; it is therefore conceivable that among the globulin, albumin, and indefinite proteoses of wheat, a fer- ment may exist capable in the presence of water of producing gliadin from some other pre-existing substance. It is difficult, however, to prove »a negative, and the onus of proving the existence of ferment action lies rather with those who are advocates of that hypothesis than with those who view it as unnecessary. Osborne and Voorhees, without actually absolutely disproving the existence of a gluten-ferment, account rationally and scienti- fically for the production of gluten on the assumption of the pre-existence of its constituents as such in the grain ; the balance of evidence is strongly in favour of the latter hypothesis. The following experiments are adduced to show that both glutenin and gliadin are necessary for the production of gluten. A portion of flour was washed free from gliadin by alcohol of 0*90 sp. gr., and next with stronger alcohol, and finally with absolute alcohol, and air dried. The residue made a tolerably coherent dough, but much less tough and elastic than that ob- tained from the untreated flour. On w’ashing this dough most carefully, not a trace of gluten could be obtained. In another experiment 7 *5 grams of finely ground air- dried gliadin w^ere mixed with 70 grams of starch, and distilled water added. A plastic dough was formed, but it had no toughness. On adding a little 10 per cent, sodium chloride solution the dough became tough and elastic. This was washed with great care with cold water, a little salt solution being added from time to time ; no gluten was, however, obtained. The following experiment shows that additional gluten is formed when glutenin is present, by the adding of gliadin. Two portions of 100 grams each of flour were taken, and to one of them 5 grams of gliadin added. Both were made into dough with the same quantity of water. The two doughs exhibited considerable differences, that containing the extra gliadin being the yellower and tougher of the tw^o. Gluten was extracted from each by washing, after which each was weighed in the wet condition, that containing the added gliadin weighed 44*55 grams, and the other 27*65 grams. On drying at 110° the yield of dry gluten Avas respectively 15*41 grams and 9*56 grams ; the difference being 5*85 grams, Avhich amount more than covers the added gliadin. On heating finely ground air-dried gliadin with a small quantity of dis- tilled water, a sticky mass is formed which, on the addition of more distilled water, forms a turbid solution. But, if to the gliadin moistened with dis- tilled water a very dilute solution of salt in distilled Avater is added, the gliadin is changed into a very coherent viscid mass Avhich adheres to every- thing it touches, and can be draAAm out into long threads. Treatment of gliadin Avith 10 per cent, salt solution, first to moisten it, and afterAA^ard in larger quantity, serves to cause the substance to unite in a plastic mass Avhich can be drawn out into sheets and strings, but is not adhesive. This explains the non-success of Weyl and Bischoff’s experiment before referred to. The gliadin is the binding material which causes the particles of flour to adhere together, thus forming a dough. But the gliadin alone is not sufficient to 116 THE TECHNOLOGY OF BREAD-MAKING. form gluten, for it yields a soft and fluid mass which breaks up entirely on washing with water. The insoluble glutenin is probably essential as afford- ing a nucleus to which the gliadin adheres, and from which it is not mechani- cally carried away by the wash water. 235. Summary. — ^The following are the properties and composition of the proteins of the wheat grain : — 1. A globulin, soluble in saline solutions, precipitated therefrom by dilution, and also by saturation with magnesium sulphate or ammonium sulphate, but not by saturation with sodium chloride. Partly precipitated by boiling, but not coagulated at temperatures below 100°. The grain contains between 0*6 and 0*7 per cent, of globulin. 2. An albumin, coagulating at 52°, which differs from animal albumin in being precipitated on saturating its solutions with sodium chloride, or with magnesium sulphate, but not precipitated by completely removing salts by dialysis in distilled water. The grain contains between 0*3 and 0*4 per cent, of albumin. 3. A proteose, precipitated (after removing globulin by dialysis, and the albumin by coagulation) by saturating the solution with sodium chloride, or by adding 20 per cent, of sodium chloride and acidulating Avith acetic acid. Separates as a coagulum on concentrating the solution, and thus yields about 0*3 per cent, of the grain. The solution from this coagulum still contained a proteose-like body which was not obtainable in a pure state. By indirect methods it is assumed to amount to from 0 *2 to 0 *4 per cent, of the grain. Both these substances,, the coagulum and the proteose-like body, are derivatives of some other protein in the seed, presumably the proteose first mentioned. As previously explained, it should be borne in mind that the proteoses may be formed during the processes of extraction by alterations of the protein matter originally present in the grain. 4. Gliadin, soluble in dilute alcohol, and soluble in distilled water to- opalescent solutions, which are precipitated by adding a little sodium chloride. Completely insoluble in absolute alcohol, but slightly soluble in 60 per cent, alcohol, and very soluble in 70-80 per cent, alcohol, and is pre- cipitated from these solutions on' adding either much water or strong alcohol,, especially in the presence of much salts ; soluble in very dilute acids and alkalies, precipitated from these solutions by neutralisation, unchanged in ])roperties and composition. The formation of gluten is largely dependent on this protein. The grain contains about 4*25 per cent, of gliadin. 5. Glutenin, a protein insoluble in Avater, saline solutions, and dilute alcohol, AA^hich forms the remainder of the proteins of the grain. Soluble in dilute acids and alkalies, and re-precipitated from such solutions by neutralisation. The folloAA'ing is the composition of these bodies : — Analyses of Proteins of Wheat. j Globulin. Albumin. 1 Coagulum. Gliadin. j Glutenin. Carbon . . 51-03 53-02 51-86 52-72 ! 52-34 Hydrogen 6-85 6-84 6-82 6-86 i 6-83 , Nitrogen. . 18-39 16-80 17-32 17-66 17-49 Sulphur . . 0-69 1-28 y 94.00 ■ 1 1-14 1-08 OxA^gen . . 23-04 22-06 ^ \j\j ^ \ 21-62 22-26 1 100-00 100-00 100-00 100-00 100-00 THE PROTEINS. 117 Wheat gluten is composed of gliadin and glutenin, both being necessary for its formation. Gliadin forms with water a sticky medium which, by the presence of salts, is prevented from becoming wholly soluble. This medium binds together the particles of flour, rendering the dough and gluten tough and coherent. Glutenin imparts solidity to the gluten, and forms the nucleus to which gliadin so adheres that it cannot be washed away with water. Gliadin and starch form a dough which yields no gluten, as the gliadin is washed away with the starch. Flour freed from gliadin gives no gluten, as there is no binding material to hold the particles together so that they be brought into a coherent mass. Soluble salts are also necessary in forming gluten, as in distilled water gliadin is readily soluble. The mineral constituents of the flour are sufficient for this purpose, as gluten can be obtained by washing a dough in distilled water. No ferment action occurs in the formation of gluten, for its constituents are found in the flour having the same composition and proportions as in the gluten, even under those conditions which would be supposed to completely remove antecedent proteins, or to prevent ferment-action. All the pheno- mena which have been attributed to ferment-action are explained by the properties of the proteins themselves, as they exist in the seed and in the gluten. The conclusions of Osborne and Voorhees agree well with the following opinions on a gluten-ferment expressed by one of the present authors in a previous work on this subject ; — “ The existence of this body cannot as yet, however, be recognised as proved. While the formation of gluten may be due to the intervention of such a body, yet there is nothing remarkable in considering it to be a simple and direct hydration, by water, of the gluten compounds existent in the grain. The effect of heating the flour, and of treatment with salt solution, are fairly accounted for by their well-knowii coagulating action on the albuminous matters. So, too, those wheats whose flours hydrate slowly are grown under conditions which favour the proteins being in a difficultly soluble condition.'' 236. Proteins of the Oat- Kernel. — ^For purposes of comparison the following statement by Osborne of the composition of the proteins of oats is given. When oat-meal is extracted with 10 per cent, sodium chloride solution, two portions of uncoagulated protein were obtained ; after which alcohol extracted another uncoagulated protein. Two distinct proteins are thus obtained from oats — that extracted from untreated oats readily coagulates and becomes insoluble in alcohol, and when wet with absolute alcohol does not absorb moisture from the air ; whilst that obtained from oats after treatment with salt solution has no tendency to coagulate, is freely soluble in cold alcohol of 0*90 sp. gr., and when wet with absolute alcohol absorbs moisture from the air and becomes gummy. Both sub- stances, when washed with absolute alcohol and dried, are light yellowish powders, soluble in dilute acids and alkalies, and reprecipitated on neutralis- ing their solutions {American Chemical Journal). 2Z1, Distribution of Proteins in Wheat. — ^The proteins of wheat are not distributed equally throughout the whole seed, there being certain portions of the wheat grain which are specially rich in soluble proteins ; the bran and germ are particularly so. Starting from the outside of the seed, the interior portions become less and less nitrogenous, until the kernel of the grain is found to consist much more largely of starch. 238. Decomposition of Proteins. — Soluble albumin, or the white of egg, on being allowed to stand, putrefies, with the evolution of sulphuretted 118 THE TECHNOLOGY OF BREAD-MAKING. hydrogen and other gases. The odour of sulphuretted hydrogen is almost invariably described by comparison to that of rotten eggs. Coagulated albumin, when dry, is a fairly stable body ; but, when left in contact with water, putrefies, yielding valeric and butyric acids, together with other bodies. The oxygen of the air has no action on albumin. Dry gluten may be kept indefinitely without change, but if when wet it is exposed, in masses too large to dry quickly, to air at ordinary tempera- tures, it gives off a quantity of gas, and at last evolves a strong putrescent odour. At the same time, the insoluble gluten breaks down into a thick creamy mass. 239. Nature of Putrefaction. — It is necessary to get accurate ideas of what putrefaction really is. Every one knows the results of putrefaction in their last or extreme stages ; animal and vegetable substances both give off gases having most disgusting odours, and yield a variety of offensive pro- ducts. These gases consist of compounds of hydrogen with carbon, and also with sulphur ; this latter gas, termed by the chemist sulphuretted hydrogen, is, as just stated, responsible for the odour so characteristic of rotten eggs. In the earlier stages, however, of putrefaction, the changes do not result in the j)roduction of such disagreeable bodies ; gases are evolved, but these are either inodorous or at most possess only slight smells. Speaking broadly, putrefaction consists of the breaking down or degrading of the complex molecules of animal and vegetable structures into compounds of a more simple character, and ultimately into inorganic compounds, such as carbon dioxide, water, and sulphuretted hydrogen ; which latter, in its turn, deposits its sulj)hur, and forms water by the action of atmospheric oxygen. Bodies in the first stage of putrefying absorb more or less oxygen ; when this element has been removed from the supernatant air, a species of fermentation, known as putrefactive fermentation, proceeds. When dealing w ith the whole question of fermentation this change must be viewed more closely. At present there is one particular point that should, however, be mentioned, and that is, that by heating any organic liquid, as a solution of hay, white of egg, or proteins of fiour, under pressure at a temperature of about 266° F. for some time, and then boiling the liquid in a flask whose neck is loosely plugged with cotton wool until the whole of the air is expelled, the liquid acquires the property of resisting putrefactive action. Solutions preserved in this manner may be kept for an indefinite length of time ; on iieing once more exposed to the air they again are subject to putrefaction. It would thus appear that putrefaction is not a process appertaining ex- clusively to the grain itself, but is in some way dependent on the action and j)resence of air. Experimental Work. 240. Reactions of Proteins. — Separate a little gluten from flour by kneading dough, enclosed in muslin, in water. Dry a little of this, and heat •strongly in a test-tube ; notice that an odour is evolved similar to that of burning hair or feathers. Water also condenses in the cooler parts of the tube ; test this water vlth a strip of red litmus paper, and notice that it has an alkaline reaction ; this alkalinity is caused by the presence of ammonia. Make a precisely similar experiment with some white of egg, and observe that the same reactions occur. Solubility . — Mix some white of egg with about four times its volume of water. Place a portion of this solution in a test-tube, float it in a beaker of cold water, and heat gently. Test the temperature at which coagulation t^n.sues. To successive portions of the albumin solution, add alcohol, ether, iuercuric chloride, and picric acid solutions, and dilute nitric acid : notice THE PROTEINS. 119 the formation of a precipitate. To the portions precipitated by acid, add caustic soda or potash solution ; the precipitates are re-dissolved. Colour Reactions . — Test the Xanthoproteic and Millon’s colour reactions, as described in paragraph 203. Precipitation . — Precipitate proteins from solutions by the various methods given in paragraph 204. Production of Peptones . — Take some of the white of a hard-boiled egg, and rub it through a fine sieve. Add to it some dilute hydrochloric acid (0*2 per cent.) and a little prepared pepsin. Gently warm the whole to a temperature of about 40° C., and notice that the white of egg dissolves. The albumin has then been converted into peptone. Soluble Flour Proteins . — Weigh out 50 grams of flour, and mix with 250 c.c. of water in a large flask, shake up thoroughly several times during half an hour, and then set aside for a few hours, or even over-night. Filter thel supernatant liquid through a French filter paper until bright. Heat a portion of this solution in a small beaker placed in a water-bath : notice the coagulation of vegetable albumin. 241. Gluten and its Constituents. — ^The separation of gluten will have been illustrated in the preceding experiments. Moisten flour with alcohol and fold up in muslin ; knead in a small vessel also containing alcohol : notice that no gluten is yielded. Make a similar experiment with a 15 per cent, salt solution ; place a sample of flour for the night in the hot water oven, and treat with ordinary water in the morning : observe in each case that no gluten is produced. Place aside some moist gluten and water in an outhouse : notice day after day the changes which occur in the appearance and physical properties of the gluten as putrefaction sets in. Take some carefully washed gluten and grind it up in a mortar with a little 80 per cent, alcohol. Transfer to a flask and keep at a temperature of 40° C. for some hours ; filter, and again grind the undissolved residuum with more alcohol in the mortar. Again digest in the flask, and once more repeat this treatment. Evaporate down the mixed filtrates over a water- bath, and notice the transparent yellow gliadin thus obtained. Carefully dry the insoluble portion, which consists of more or less pure glutenin. The extent to which this series of experiments is carried must depend on the time and opportunities of the student, and also the laboratory facilities at his disposal. CHAPTER VIII. ENZYMES AND DIASTATIC ACTION. 242. Hydrolysis. — ^It has already been incidentally mentioned that starch may readily be converted into dextrin and maltose ; Avith regard to the carbohydrates generally, one of their special characteristics is, that the less hydrated members of the series are easily changed to those con- taining a higher proportion of hydrogen and oxygen. In consequence of the great importance of these transformations, they will require to be dealt with fully. The present chapter will, therefore, give particulars of the nature of these changes, the agents by which they are effected, and the conditions which are favourable or unfavourable to their occurrence. As the mutations of the carbohydrates consist of the addition of the ele- ments of water to the atoms previously present in the molecule, it has been proposed to include these changes under the general term “ hydrolysis."" Hydrolysis is, therefore, defined as a chemical change, consisting of the assimilation, by the molecule of the substance acted on, of hydrogen and oxygen in the same proportions as they exist in water ; and resulting in the producticn of a new chemical compound or compounds. Those bodies capable of producing hydrolysis are termed “ hydrolysing agents "" or “ hydrolytics."" In order that hydrolysis may occur it is obviously necessary that water shall be present. 243. Hydrolytic Agents. — ^These bodies include oxalic and dilute hydro- chloric and sulphuric acids. Commencing with soluble starch, the acids mentioned possess the power of converting that body first into dextrin and maltose, then into glucose. The acid hydrolytics also transform cane sugar into glucose. It will be noticed that the ultimate products of hydro- lysis of starch are sugars of various descriptions, hence this operation is frequently termed the “ saccharification "" of starch. 244. Saccharification of Starch by Acids. — This operation is carried on as a commercial process for the manufacture of glucose for use in breAving. The starch is boiled, either in open vessels or under pressure, Avith dilute sulphuric acid. If the operation be stopped as soon as a portion of the solution gives no blue colouration when tested AA’ith iodine, it will be found that dextrin and maltose are the chief products. Continued boiling results in the transformation of most of the dextrin and maltose into glucose. The sulphuric or oxalic acid, Avhichever is used, is next removed by the addition of calcium carbonate in slight excess. This reagent forms an insoluble oxalate Avith the latter acid, and Avith the former, calcium sul- phate, Avhich is only very slightly soluble. The precipitate is allowed to subside and the supernatant liquid evaporated under diminished pressure. 245. Catalysis. — ^When soluble starch is saccharified by the action of an acid such as oxalic acid, it is found that the acid itself does not disappear during' the reaction. If the necessary precautions be taken, the same quantity of unaltered acid is found at the termination of the chemical cliange as Av^as introduced prior to its commencement. This leads us to institute a comparison betAA^een actions of the type now under consideration • and others frequently met Avith in more general chemistry. Taking chem- 120 ENZYMES AND DIASTATIC ACTION. 121 ical changes as a whole, they may be resolved into those of two classes, -(1) those in which the reaction is practically immediate on the mixture of the interacting bodies, as when hydrochloric acid and sodium hydroxide are added to each other in solution and at once form the neutral sodium chloride, and (2) those in which the chemical change occupies an appreciable time. As an illustration of the latter the combination of sulphur dioxide with oxygen to form sulphur trioxide in the presence of water may be men- tioned. Now in the case of many reactions of the second type, there are .substances which remarkably accelerate the speed of the reaction, without themselves undergoing a permanent chemical change. Thus, if a small quantity of nitrogen oxide, NO, be added to the aforesaid mixture of sulphur dioxide and oxygen, it marvellously increcoses the rapidity of combination of these bodies, and that without in itself undergoing permanent alteration. This is, in fact, the method employed in the manufacture of sulphuric acid, and were there no purely secondary reactions, the nitrogen oxide might be entirely recovered as such at the close of the chemical process. This process of changing the rate of a slow chemical action is termed “ catalysis,” and the active agent therein is termed a “ catalyst.” Among the essentials of catalytic action is that the catalyst does not induce the chemical change but only alters the rate of one already proceeding ; and further, the catalyst does not combine with any of the products of the reaction. In the case of many chemical reactions, an important point is that they only proceed until a certain condition of equilibrium is reached. Thus if a compound is subjected to such conditions as lead to its dissociation into the constituent elements, there is a position in which there will be neither complete combination nor complete dissociation. There will be simultaneously present free atoms or molecules of the elements and molecules of the compound. If an additional quantity of the compound is added, dissociation will proceed until the point of equilibrium is again reached ; or if combining proportions of the elements are added, combination will •ensue till again the position of equilibrium is attained. In a chemical reaction that is accelerated by the introduction of a catalyst, and in which there is an intermediate point of equilibrium, the same catalyst that speeds the reaction to this point will have a reverse action if added to the sub- stances beyond the equilibrium point. Thus taking the hydrolysis of cane sugar to glucose, there is in fact a point at wdiich the action ceases, and on that point being reached, there is present some cane sugar and also glucose and fructose. If glucose and fructose only be subjected to the action of the same catalyst, a reverse action proceeds until cane sugar and glucose and fructose are present in equilibrium quantities. Thus the same catalyst which hydrolyses cane sugar .into the simpler bodies, may also synthesise cane sugar from these substances. 246. Enzymes or Soluble Ferments. — Another most important group of catalytic agents, which are capable of inducing hydrolysis, consist of certain soluble bodies of organic origin. Among such substances are human saliva, filtered aqueous infusions of yeast, flour, bran, and malt. Chemical research show s that in each case hydrolysis is due to the nitrogenous con- stituents of these various agents. In several instances the active principle has either been isolated or obtained in a very concentrated form ; it is not known, however, wdth certainty w^hether these bodies are definite chemical compounds, or w^iether they are only mixtures of certain nitro- genous bodies in a particularly active state. These substances form part of a yet larger group of bodies which for- merly were indiscriminately classed together as “ ferments,"" that is, bodies which were capable of inducing fermentation. At present this latter term, 122 THE TECHNOLOGY OF BREAD-MAKING. as is explained in a subsequent chapter, is confined to those chemical actions which are the work of certain micro-organisms ; and the changes, such as hydrolysis, that are due to active principles which are not organised or living, form a separate class. These active principles have been termed soluble-ferments ; but, as in order to avoid confusion with micro-organisms and fermentation, it is well to dissever them entirely from the idea of fer- mentation, the term “ enzyme has been proposed, and is now generally adopted. It has also been proposed to group together all the chemical changes due to enzymes under the generic term of “ enzymosis.’’ A number of chemical reactions are brought about by enzymes, most of which, however, are instances of hydration of the bodies acted on. Enzy- mosis occurs usually most readily at temperatures about 40° C., and is characterised by the fact that a minute quantity of the enzyme is capable of causing the characteristic chemical change in a comparatively enormous quantity of the substance acted on, without itself apparently undergoing change. In other words, these substances behave as catalysts. An enzyme may therefore be defined as a substance produced by living organisms, and capable of acting catalytically on contiguous compounds. 247. Chemical Properties of Enzymes. — These substances can be extracted from the bodies containing them by the action of water, dilute alcohol, salt solutions, or glycerin. From these solutions they may be precipitated by strong alcohol, lead acetate, or saturation with ammonium sulphate. This precipitate, on being washed with absolute alcohol and dried in vacuo, yields a friable mass easily reduced to a white powder, and in composition either protein or closely allied to protein matter. The enzymes act most vigorously at a temperature of from 40 to 45° C., and are, in the moist state, destroyed by a temperature of from 50 to 75° C., according to the nature of the enzyme. (Certain enzymes when absolutely dry withstand a temperature of as much as 170° C.) The presence of free acid or alkali, and also small quantities of certain neutral salts, as ammonium sulphate, are inimical to enzymosis. 248. Classification of Enzymes. — ^Among the number of enzymic actions, comparatively few are of importance in the study of the present subject ; these are placed first in the accompanying table, while others of less imme- diate value, but still of interest as illustrative of the whole scheme of enzymosis, follow. Osborne and Voorhees’ researches rather negative the existence of Weyl and Bischoff’s hypothetical vegetable myosin ; but, if the contrary were the case, the natural place of this enzyme would be as shown in class 6. The fact that there are members of this class which can perform analogous functions in blood and muscle did much toward paving the vay for the inception of the theory of there being a gluten-forming enzyme. 249. Cytase. — ^As early as 1879, Brown and Heron mentioned that during the germination of grain the cellulose cell- walls, and also the cellulose of the starch granules, are broken down. Brovn and Morris again call attention to the same fact in their paper on the “ Germination of some of the Graminese,” Jour. Chem. Soc., 1890, p. 458. As germination pro- ceeds, tlie parenchymatous cell-walls of the endosperm are gradually dis- solved, and ultimately leave no sign of separation between the contents of the contiguous cells. During the progress of these changes the endosperm is much softened, and attains the condition of “ mealiness ” aimed at by the maltster in course of the germination of barley in malt manufacture. Brown and Morris find that this production of mealiness is undoubtedly co-terminous with the dissolution of tlie cell-wall, and, contrary to what is usually believed, is entirely independent of tlie disintegration of the Zf) s pR o ZT} H O) ’S Ei) 'o jn OJ 4:i o ^ '3 i: s' •I— j o ® • .2 ^ ■§ 1 1 U C6 2 eg eg ro TO rr ccPh ^ cd O 0 IR 50 W *<: (7^ ^ N _d _cS _o3 __c« 0 S ^ ^ R M >1-^ 0 “ •5 ^ a § QPh^p; o o3 ce .5 2 ^ ?-l c5 0 CD gfeS h- f I— I 2 O ^ cs © «S- O^.S "rd R ,1 © 13 TP ~R d 0 cS ? ° -5 Is g a O-S |.s ot II ^ ® .d © ’S .•| ^ 8-“ 'd o .S •^’■^ 0 ^ d 1 is cS i © 0^0 gd © © ^ K cS ©-2 |2 SrS d ri-T R d o © •S M ^ ^ ® Cd-R 13 A >J O o © R R Ph H fid d .S '© 2 M .R 5 s § .1 IgS >75 « > o © docd Q o qp . © 03 o § ^ © &JD © > o CO ©‘ CO cS P >3 N ■s1« . a a a R ' R © d rj ^'V 03.2 . i.a o^ R o ^ a ^ pp c d: o o Is o 03 _d § feo d TJ d 0 Ph 1 o CJ © > © > © © > 'Jo Ri "o © WJ CS 3 *io © > o B bX) cS *3 c R >3 o B (d( N t> a CO >© o rd li3 00 Myrosin. Mustard. •• Stsatolytic . . Separation of fats into fatty acids and glycerin. Steapsin. Pancreatic juice 124 THE TECHNOLOGY OF BREAD-MAKING. starch-granule. The enzyme, which thus dissolves the parenchymatous cell- walls of the endosperm, has received the name Cytase. Cytase is secreted by the embryo during germination, and is found in considerable quantity in green- or air-dried malt, but is readily destroyed by the action of heat, and so is found in only very limited quantity in kiln-dried malt, especially that which has been subjected to a somewhat high temperature. That cytase is not identical with diastase is demonstrated by the fact that, where- as a filtered aqueous extract of air-dried malt dissolves the cell- walls of the endosperm, this power is lost on subjecting the liquid to a tempera- ture of 60° C., which temperature does not destroy the vitality of diastase. 250. Diastase. — ^Since the “ mashing ” or maceration of malt with water at about a temperature of 60° C. has been employed as one of the operations in the brewing of beer, it has been well known that during this process the starch of the malt is converted into some form of sugar. Payen and Persoz, in 1833, stated that the action of an infusion of malt on starch was due to the presence of a particular transforming agent to which thej’ gave the name of diastase. , Investigation show^s that diastase is secreted by the embryo of such plants as wheat and barley during germination — in a subsequent chapter the physiology of its production and action is dealt with somewhat fully. Diastase is present in large quantity in air-dried malt, and to a lesser but still eonsiderable extent in the malt after kiln-drying. For its extraction in a concentrated form, Lintner recommends the following method : — 1 part of green malt or sifted air-dried malt is ex- tracted with 2 to 4 parts of 20 per eent. alcohol for 24 hours. At the end of this time as much as possible of the liquid is filtered off by means of a press, then filtered through paper until bright. To this filtered extract 2J times its volume of absolute alcohol is added, resulting in the production of a precipitate, which is allowed to settle, and washed on a filter with abso- lute alcohol. The precipitate is then transferred to a mortar and rubbed down with absolute alcohol, once more transferred to a filter and washed with absolute alcohol, and ether. Finally it is dried in vacuo over sul- phuric acid. Prepared in this, manner, diastase consists of a yellowish- white powder of great diastatic activity. Its purification is effected by repeatedly dissolving in water and re-precipitating by alcohol. Subjecting the aqueous solution to dialysis reduces the quantity of ash (which con- sists of normal calcium phosphate) and also increases the percentage of nitrogen. A purified diastase gave the following numbers on analysis calculated on the ash-free substance. Results of analyses of other enzymes are also given. Composition of Various Enzymes. Diastase. Pancreatic Enzyme. Invertase. j Emulsin. j 1 Carbon . . 46-66 46-57 43-90 ' i i 43-50 Hydrogen 7-35 7-17 8-40 7-00 Nitrogen . . 10-42 14-95 9-50 11-60 1 Sulphur . . 1-12 0-95 0-60 1-30 Oxygen . . . . . . 34-45 30-36 37-60 36-60 100-00 100-00 100-00 i 100-00 Authority Lintner. 1 Hiifner. Barth. j Bull. ENZYMES AND DIASTATIC ACTION. 125 More recently Osborne lias prepared diastase from malt in another manner. The ground malt was first extracted with water and filtered. To the filtrate ammonium sulphate was added to saturation, and the pro- teins thus precipitated. The precipitate was suspended in water and subjected to dialysis, thus removing much of the ammonium sulphate ; there remained a residue of a globulin character, and this was filtered off. The filtrate was again saturated with ammonium sulphate, the precipitate suspended in water, once more dialysed, and filtered, thus getting rid of most of the globulins. The resulting solution of proteins was next dialysed into alcohol, with the formation of some precipitate. This was filtered off, and the solution again dialysed into more alcohol, with the formation of a further precipitate. The operations of dialysis and filtration were repeated until altogether five fractions of precipitate had been obtained. The precipitates were purified by solution in water, filtration, dialysis first into water, and afterwards into alcohol, and finally re-precipitated by the addition of absolute alcohol and dried. The fourth fraction was far higher in diastatic power than any of the others. This preparation was soluble in water, became turbid at 50° C., and gave a large coagulum at 56° C. The filtrate from this gave the biuret reaction, thus showing the presence of proteoses. This preparation had a diastatic power of 600° Lintner and was the most active diastatic substance on record. Analysis showed it to contain 0*66 per cent, of ash, and allowing for this it had the following composition : — Carbon ......... 52*50 Hydrogen ......... 6*72 Nitrogen ......... 16*10 Sulphur ......... 1 *90 Oxygen ......... 22*78 100*00 The composition is that of a normal protein, save that the sulphur is somewhat high, but this may be accounted for by the possible presence of a little ammonium sulphate. On further investigation, this substance was found to have the same coagulating temperature as leucosin (albumin of wheat or barley), and Osborne regards albumin as being the diastatic body. But the amount of diastatic action is not proportional to that of albumin, amd therefore Osborne suggests the hypothesis that diastase is a compound of albumin M'ith possibly proteose, but of this theory there is at present no direct proof. During the passage of this work throught the Press, the Malt-Diastase Company of New York have forwarded the authors a sample of exceedingly concentrated malt diastase, prepared in their laboratory, which has the following remarkable converting power : — (1) One part by weight will convert 150 parts by weight of starch into dextrin and maltose, within ten minutes at 99° F. (2) One part will produce from a surplus of starch, 329 parts of maltose within thirty minutes at 99° F. ■ (3) Tested according to Lintner’s method, this diastase has a strength of 4,705°. Diastase gives with tincture of guaiacum and hydrogen peroxide a blue colouration, which is soluble in ether, benzene, chloroform, and carbon disulphide, but not in alcohol. This reaction of diastase is shared by other enzymes, and is caused by the presence of peroxydase. This latter sub- stance may be regarded as an enzyme having an oxidising action as distinct from the hydrolysing actions before described. 126 THE TECHNOLOGY OF BREAD-MAKING. Diastase in the pure form does not reduce Fehling’s solution, and, as may be judged from its very nature, is marked by a great capacity for liquefying starch paste and saccharifying it into dextrin and maltose. Unlike the acids, diastase, however, is incapable of converting starch fur- ther than into dextrin and maltose. Diastase readily changes amylo- dextrin and maltodextrin completely into maltose, but does not under any circumstances further hydrolyse maltose. Under favourable circumstances, one part of well-prepared diastase, such as that of Osborne, is stated to suffice for the conversion of 2000 parts of starch. A dilute solution of diastase is exceedingly unstable, rapidly becoming acid, and losing its power of starch conversion. This does not apply to concentrated solutions of diastase in the presence of sugars such as are obtained by concentrating in vacuo cold-water extracts of malt to the consistency of a sirup. 251. Diastatic Action or Diastasis. — The action of diastase, being of of such great importance in brewing operations, has been studied closely. The term “ diastase is occasionally used in a generic sense, and is then applied to the hydrolysing agents of the cereals generally ; thus cerealin is at times referred to as the “ diastase of bran. Hydrolysis, when effected by diastase or its congeners, is often termed diastatic action, for which the shorter term “ diastasis ” is sometimes used. 252. Measurement of Diastatic Capacity. — ^The activity of malt extract, or of the purer forms of diastase, depends on the degree of concentration, temperature, and other conditions. Kjeldahl has enunciated what is known as the law of proportionality. The amount of diastase in two malt extracts is proportional to the reducing power which they effect, providing that both act on the same quantity of starch during the same period of time, and that the cupric oxide reducing power (K) does not surpass 25-30. If the whole of the starch present were converted into maltose, K would be 62*5 ; according to this stipulation, therefore, some- what less than half the starch must undergo conversion into maltose, or, in other words, starch must be to that extent in excess of the amount hydro- lysed by the diastase. Unless the starch is thus largely in excess, the diastatic action will not be proportional to the amount of diastase. Lintner measures the diastatic capacity on soluble starch, prepared as directed in Chapter VI., paragraph 172, and terms the diastatic activity of the precipitated diastases as 100, when 3 c.c. of a solution of 0*1 gram of diastase in 250 c.c. of water, added to 10 c.c. of a 2 per cent, starch solution, produces in one hour, at the ordinary temperature, sufficient sugar to reduce 5 c.c. of Fehling’s solution. These quantities amount to 0*0012 gram of diastase, acting on 0*2 gram of soluble starch, while the maltose necessary to reduce 5 c.c. of Fehling’s solution is 0*0400 grams. This quantity of maltose produced is approximately equal to 0*05 grams of starch reduced, and the diastase will have hydrolysed about 41 times its weight of starch in the time and under the conditions specified. Direc- tions for the determination of diastase by methods based on this principle are given in the analytic section of this work. The above is simply a mode of determining diastatic activity, everything else being equal. The con- sideration of how diastatic capacity is affected by changes of temperature and Qtlier conditions is described in detail in subsequent paragraphs. 253. Nature of Diastase. — The effects of diastase on starch have already been spoken of as including two distinct actions ; first, the liquefying of starch paste, converting it, in fact, into soluble starch ; and second, the saccharifying of tliis previously liquefied starch. Certain forms of diastase ENZYMES AND DIASTATIC ACTION. 127 possess this latter power only ; but it is usually assumed that malt diastase possesses the two properties. More recently, the opinion has been growing that malt diastase consists of two distinct enzymes — the one a liquefying, and the other a saccharifying agent. More will be said on this matter when dealing with the diastase of unmalted grain. There naturally arises, in conjunction with the study of diastase, the speculation whether diastase is a distinct chemical compound of nature allied to the proteins, or a property or function certain protein bodies are capable of exercising under special conditions. Certainly, in the purest form hitherto isolated^, diastase is obtained by processes which secure soluble proteins in the purest state ; and, practically, any substance called diastase is unobtainable as distinct and separate from soluble proteins. Brown and Heron finding that, on heating malt extract to a temperature of about 46° C., the soluble proteins commence to coagulate ; a continu- ance of this temperature for some 15 to 20 minutes effects the maximum amount of coagulation possible at 46° C. On raising the temperature a few degrees, an additional quantity of proteins coagulate ; this further increase of coagulation continues, as the temperature rises, up to about 95° C. The proteins of malt extract may be viewed as being composed of distinct fractions, each of which has a definite coagulating point, varying from 46° to 95° C. With the coagulation of the proteins, the diastatic power of the malt extract diminishes ; also, no diminution of starch con- verting power has been observed without a coagulation of proteins. Fur- ther, at the point at which the diastatic power of malt extract is destroyed (80-81° C.), nearly the whole of the coagulable proteins have been pre- cipitated. Brown and Heron “ are consequently led to conclude that the diastatic power is a function of the coagulable proteins themselves, and is not due, as has been generally supposed, to the presence of a distinctive transforming agent/" They further find that filtration through a porcelain diaphragm results in the production of a liquid which, on being heated to the boiling point, throws down no proteins. This filtered malt extract they find to be incompetent to produce diastasis, possessing “ absolutely no transforming power."" It is therefore possible to remove the diastatic agent from the malt extract without the application of heat. 254. Action of Diastase on Starch. — This reaction may first be summed up briefiy by stating that if a cold infusion of malt be made, and then fil- tered ; it, the infusion, on being added to a solution of starch in water, at temperatures from 15° to about 70° C., more or less rapidly hydrolyses the starch into a mixture of dextrin and maltose. The longer the operation is continued, the higher is the proportion of maltose produced ; but even prolonged action does not result in any further hydrolysis of the maltose into glucose. The investigation of starch and its transformation products has for many years occupied the close attention of what may be called the Burton School of Chemists. Prominent among these are the names of 0"Sullivan, Brown, Heron, and Morris. By these and other writers, a number of papers of singular interest and value have been contributed to the Journal of the Chemical Society. The following paragraphs (255-261) consist largely of a summary of the conclusions arrived at and adduced in these papers, after careful collation with each other, and the work of other investigators. Brown, Heron, and Morris’ Researches. 255. Malt Extract employed. — It was found that a cold aqueous infusion of malt was he most convenient diastatic agent to employ, as diastase when employed in a pure state was liable to considerable variations in 128 THE TECHNOLOGY OF BREAD-MAKING. activity. With proper precautions, the aqueous infusion of malt admitted' of any degree of accuracy. The infusion or malt extract was prepared by mixing 100 grams of finely ground pale malt with 250 c.c. of distilled water. This mixture was well stirred and then allowed to stand for from six to twelve hours, and then filtered bright. This extract had a specific gravity of 1036-1040. 256. Action of Malt Extract on Cane Sugar. — ^Malt extract is capable of “ inverting "" cane sugar, i.e., changing it into glucose. The term “ in- verting ” is derived from the fact that the resulting mixture of glucoses exerts a left handed rotary action on polarised light, while the original sugar is dextro-rotary. The maximum effect is produced at about 55° C. ; it is much weaker at 60°, almost destroyed at 66°, and entirely destroyed by boiling. 257. Action of Malt Extract on Ungelatinised Starch. — ^According to Brown and Heron’s earlier researches, malt extract is incapable of acting on unaltered starch ; and even when contact between the two is main- tained for a considerable time, not the slightest action is perceptible at ordinary temperatures. Notwithstanding this, it is well known that the starch of seeds is attacked and dissolved during the natural act of germination ; but this action they viewed as being inseparable from the living functions of the vegetable cell. This statement is at variance with that of Baranetzky, who avers that “ the starch granules of different kinds are acted on with unequal rapidity by the diastatic ferments of plant juices, the strongest ferment of all, malt diastase, being w^ell known to have no perceptible influence, even after long exposure, on solid potato-starch granules, while wheat and buck- wheat are dissolved with facility.” In a more recent paper on “ Germination of some of the Graminese,” 1890, Brown and Morris refer to Brown and Heron’s paper of 1879, and the conclusion therein expressed is that ungelatinised starch is not acted on by malt extract, no “ pitting ” of the granule or disintegration being produced by artificial means. .They also refer to Baranetzky ’s memoir, and confirm his statement that solid potato-starch granules (which had been exclusively used by O’Sullivan and themselves in their previous researches) are highly resistant to diastase. They further find that well-washed and highly purified barley-starch is in a few days “ pitted,” disintegrated, and dissolved by a cold-water extract of air-dried malt, the action being facilitated, as shown by Baranetzky, by the presence of a minute quantity of acid. They treated some well-purified ungelatinised 5rtr^ey-starch with a solution of precipitated malt diastase, to which 0 0065 per cent, of formic acid had been added. (Acid of this degree of concen- tration has no action on barley-starch.) A trace of chloroform had also been employed in order to prevent putrefactive changes. The starch was vigor- ously attacked, with the production of maltose as the only optically active substance produced. At higher temperatures, diastase or malt extract acts on ungelatinised starcli ; thus Lovibond (“ Brewing with Raw Grain ”) states that the diffusive action of the diastase through the starch cell-wall is sufficient at liigli temperatures, to effect the hydrolysis of the starch granulose. The temperatures at which he worked were, however, not much below those given for incipient gelatinisation. The authors also find that on mashing wheat flour witli malt extract for some time at temperatures- below the gelatinising point, considerable quantities of starch suffer hydro- lysis. Lintner gives the following table of the quantities of ungelatinised ENZYMES AND DIASTATIC ACTION. 129 starch dissolved by treatment with malt extract at various temperatures. The digestion was allowed to proceed for four liours, but in the case of the higher temperatures was practically complete in about twenty minutes. Tlie results are given in percentages of the total starch taken for the experi- ments : — Action of Malt Extract on Ungelatinised Starch. 50° C. 55°C. 60° C. 65° C. Potato Starch . . Per Cent. 013 Per Cent. 5-03 I Per Cent. 52-68 Per Cent. 90-34 Rice ,, 6-58 9-68 19-68 31-14 Wheat ,, — 62-23 91-08 94-58 Maize ,, 2-70 — 18-50 54-60 Rye 25-20 • — ■ 39-70 94-50 Oat ,, 9-40 48-50 92-50 93-40 Barley 12-13 53-30 92-81 96-24 Green Malt Starch 29-70 58-56 92-13 96-26 Kilned ,, 13-07 56-02 91-70 93-62 258. Action of Malt Extract on Bruised Starch. — As the next step in the investigation, some starch was triturated in a mortar with powdered glass. This treatment results in cutting the cellulose envelopes of the granules. The starch granulose is then exposed, and on being treated with malt extract rapidly undergoes conversion. The product consists principally of maltose, the actual results obtained in one experiment being that, after remaining six hours, the clear solution contained — Maitose . . . . . . . . . 86*3 , Dextrin . . . . . . . . .10*5 Cellulose . . . . . . . . . 3 *2 100-0 After twenty-four hours in the cold the maltose had suffered a slight increase : — Maltose . . . . . . . .91*4 Dextrin . . . . . . . . . 70 Cellulose . . . . . . . . . 1 *6 100-0 It will be noticed that under these circumstances a ^mall quantity of cellulose becomes dissolved. 259. Action of Malt Extract upon Starch Paste in the Cold. — At ordinary temperatures malt extract acts upon starch paste (gelatinised starch) with great rapidity and energy. In 100 c.c. of starch solution, containing be- tween 3 and 4 per cent, of solid matter, the addition of from 5 to 10 c.c. of the malt extract causes the starch to become perfectly limpid in from one to three minutes. Immediately after arriving at this point the solution ceases to give a blue colouration with iodine. Amyloins are shown to be present by the brown reaction with iodine, and do not disappear within some five or six minutes from the commencement of the experiment. In this case also a small quantity of starch cellulose is dissolved, but is slowly K 130 THE TECHNOLOGY OF BREAD-MAKING. re-deposited on the liquid standing. After remaining three hours, three experiments gave a mean of — Maltose . . . . . . . . . 80 *4 Dextrin ......... 19*6 100-0 as the composition of the solution, resulting from hydrolysis by malt extract. 260. Action of Malt Extract at higher temperatures. — ^At temperatures of 40° and 50° C., the ultimate products of the action of malt extract are found to be practically the same as in the cold, but the point of dis- appearance of amyloins is reached somewhat less rapidly. At 60° C. the action is weakened, but still proceeds sufficiently far to produce practi- cally the same amount of maltose. At still higher temperatures the transformation of the dextrin, first formed, into maltose goes on much more slowly. Also, the action of the diastase of the malt extract may be weakened by the addition to it of dilute alkalies. Such treatment results in limiting the extent to which the conversion of dextrin into maltose proceeds. The results may be summed up by stating that, by modifications of the treatment of starch paste with malt extract, certain fixed points may be obtained representing several different molecular transformations of starch. 261. Molecular Constitution of Starch, Dextrin, anl Maltose. — ^The historical development of the modernly held hypothesis of the molecular constitution of starch is, in view of the importance of the subject, of con- siderable interest. Brown and Heron, in their paper on “ Starch and its Transformations,'' 1879, considered that the most natural conclusion that can be derived from the varying proportions of dextrin, obtained in modi- fications of the hydrolysis of starch paste by malt extract, is that there are several dextrins, and that these dextrins are polymeric, and not meta- meric bodies. Having adopted this view. Brown and Heron's results led them to the opinion that the simplest molecular formula for soluble starch is IOC12H20O10, which may also be written Ci2xioH20xioGioxio* The first change produced by the addition of malt extract would, then, be represented by — C 12 X 10H20 X loG 10 X 10 Soluble Starch. II2O — C12 X9H20 xoOiO x9 Water. Erythro-dextrin. a. C12H22O 11. Maltose. That is, one of the groups of Ci2H2oOio having combined with water to form maltose, the remaining nine groups constitute the first or most com- plex dextrin. By the assimilation of another molecule of water, the nine- group dextrin breaks up into a second molecule of maltose and an eight- group dextrin. This reaction proceeds through successive stages until finally the one-group dextrin, Ci2H2oOio, is in its turn transformed into maltose. There are thus theoretically possible nine polymeric modifica- tions of dextrin ; the two higher of these are erythro-dextrins ; the remaining seven are achroo-dextrins. The most stable of the whole of these dex- trins is that resulting from the eighth transformation, having the compo- sition C12X2H20X2O10X2 • the hydrolysis of starch, with the production of tliis dextrin, would then be represented by — Gi 2 x I0H2OX loGiOx 10 8H2O — Ci 2 x 12H2OX2O1OX2 8 Ci 2 H 220 ii. Soluble Starch. Achroo-dextrin. ^ Maltose. In the more recent paper by Brown and Morris (“ The Non-cry stallisablc Products of the Action of Diastase upon Starch," 1885), they adduce evidence in favour of a third body, maltodextrin, being formed as an ENZYMES AND DIASTATIC ACTION. 131 intermediate product during the hydrolysis of starch ; as previously mentioned, they ascribe to this body the formula, - C12H20OJ0. From (C12H20O10 this it will be seen that maltodextrin is composed of a molecule of mal- tose united with two of the one-group dextrin. Viewed in the light of the existence of this intermediate product, they then regarded the fol- lowing as the simplest molecular formula for starch, capable of accounting for the various reactions observed during its hydrolysis — /(C12H20O 10)3 I (Ci 2 H 2 oOio )3 ■j (C12H20O 10)3 I (C12H20O 10)3 (Ci 2 H 2 oOio )3 In accordance with this hypothesis, the first step in hydrolysis consists in the lesion of one of the ternary groups, which is transformed into malto- dextrin by the assimilation of a molecule of water, thus — (C.H.„0.), + H.0 = {fc'Sfo”). One of the five ternary groups Water. Maltodextrin. constituting the starch molecule. Malt extract effects the complete conversion of maltodextrin into maltose — fCi 2 ll 2 20 ii I qtt r\ TT 1 /r< TT rk \ > ^Xl2V^ — 'J'- 12^^22'-' n» '' ^'-^ 12 - 0 - 20 '-' 10/2 Maltodextrin. Water. Maltose. In the change producing maltodextrin, the remaining four ternary groups of (Ci2H2oOio) 3 unite to form the most complex of the dextrins. As the hydrolysis continues, the remaining ternary groups undergo suc- cessively the same change until one only remains : this is identical with that before referred to as achroo-dextrin The view that the starch mole- cule contains fifteen of the C12II20O10 group instead of ten, requires that this, which may be distinguished as “ stable dextrin,"" shall consist of three groups of C12II20O10 instead of two : this, of course, makes the formula the same as that of one of the ternary groups. The reaction for the pro- duction of stable dextrin is then represented by the following equation : — - '(C12II200 10)3 (C12II200 10)3 (C12II20O10 -^(Ci 2 H 2 oOio )3 + I2H2O = Ci 2 H 2 oOm + 12 Ch 2 H 220 „. (Ci 2 ll 2 oOio )3 IC12II20O10 ,(^ 12^200 10)3 Soluble starch. Water. Stable Dextrin. Maltose. Such, very briefly summarised, were the opinions advanced by Brown, Heron, and Morris, up to 1885 , as to the relative molecular constitutions of starch, dextrin and maltose. In 1888 and 1889 , Brown and Morris contributed to the Chemical Society's J our nal t\Yo m.o^t important papers on “ The Molecular Weights of the Carbohydrates.” To these papers reference has already been made in the commencement of Chapter VI. By the application of Raoult"s method, the molecular weights of starch and the products of its hydro- lysis were definitely determined. Among these determinations, probably the most important was that of dextrin. This was made as a preliminary to the estimation of that of soluble starch. It has been already shown that these chemists view starch as a compound of five dextrin groups. In their 1889 paper they say : — 132 THE TECHNOLOGY OF BREAD-MAKING. ‘‘ When the complex molecule of starch is broken down by diastase, under the conditions most favourable to its complete hydrolysis, we have shown that a point of equilibrium, or, speaking more strictly, a resting point in the reaction is reached, when the amount of dextrin produced corresponds to one-fifth by weight of the amount of starch taken ; that is, when the mixed products have [a] j 2- sq = 162*6° and K3.86 = 49*3. “ This reaction is represented in the simplest form by 5 C 12 H 20 O 10 “h 4 H 2 O = C 12 H 20 O 10 4Ci2H 220ii. starch. Water. Dextrin. Maltose. If the production of maltose and dextrin during hydrolysis is to be considered as due to a molecular degradation of the starch, and we think the evidence in favour of this is almost conclusive ; then, no matter what view we may take of the actual manner in which this degradation takes place, we cannot escape from the conclusion that the molecule of stable dex- trin of the above equation is one- fifth of the size of the soluble starch molecule from which it has been derived” Brown and Heron determined by RaoulFs method the molecular weight of this dextrin, and thus indirectly that of starch. In the next place they proceeded to consider whether Raoult’s method was capable of throwing any light on the relations of the dextrins to each other, it being a matter of the highest theoretical importance to determine whether these bodies constitute a series of polymers, or whether they stand merely in metameric relation to each other. Accordingly some of the so-called higher dextrins were prepared ; that is, those which result from starch hydrolysis arrested at its earlier stages. A comparison of the results thus obtained afforded no evidence of there being any difference in the molecular weights of the higher and lower dextrins. Brown and Morris summarise their conclusions by saying that there being no differences in the various dextrins when treated by Raoult’s method, “ goes, in our opinion, a long way towards proving that,' after all the dextrins are metameric, and not polymeric. If this is admitted as even probably correct, it becomes necessary to consider how far our previous views on the breaking-down of the starch molecule must be modified in order to include the new facts.” Brown and Morris enunciate the following hypothesis as being more in accord with the facts : — “ We may picture the starch-molecule as consisting of four complex amylin-groups arranged round a fifth similar group, constituting a molecular' nucleus. “ The first action of hydrolysis by diastase is to break up this complex molecule, and to liberate all the five amylin-groups. Four of these groups when liberated are capable, by successive hydrolysations through malto- dextrins, of being rapidly and completely converted into maltose, whilst the central amylin nucleus, by a closing up of the molecule, withstands the influence of hydrolysing agents, and constitutes the stable dextrin of the low equation, which, as we know, is so slowly acted upon by subsequent treatment with diastase. The four readily hydrolysable amylin-groups we look upon as of equal value, and in their original state these constitute the so-called high dextrins, which can never be separated completely from the low dextrin by any ordinary means of fractionation. ‘‘ This hypothesis provides for intermediate maltodextrins or amylo- dextrins, whose number is only limited by the size of the original amylin- grou}).^ Each amylin-group of the five has a formula of (Ci 2 H 2 oOio) 2 o> a-nd a molecular weight of 64S0 ; so that the entire starch-molecule, or, more correctly speaking, that of soluble starch, is represented by 5(Ci2H2oOjo)-:u> having a molecular weight of 32,400.” ENZYMES AND DIASTATIC ACTION. 133 In their Text Book of the Science of Brewing, publislied in 1891, Moritz and Morris further explain that probably the outer amylin-groups cannot ■exist as such, but immediately on separation from the central nucleus are partially hydrotysed, yielding amyloins of possibly the very highest type. These amyloins are gradually hydrolysed, being split up into smaller aggrega- tions, which constitute the various maltodextrins. Brown and Millar, in a paper contributed to the Journal of the Chemical Society in 1899, point out that the so-called stable dextrin has a cupric reducing power of B 5 *7-5 *9, and therefore must contain a glucose group. According to this view, the hydrolysis of starch is thus represented : — lOOC.^H^oO.o + 8IH2O = 8OC.2H22O:. (t 61112^6 Starch. Water. Maltose. Stable Dextrin. 262. Effect of Heat on Diastasis. — The rapidity of diastatic action is ■considerably influenced by variations of temperature ; extreme cold practi- cally inhibits it. Starting from ordinary temperatures, diastasis rapidly increases as the temperature rises, until, according to Kjeldahl, 54° C. (129° E.) is reached — from that temperature until 63° C. (145° E.) it remains fairly constant, and then rapidly decreases with any further rise in tempera- ture, being entirely destroyed at 10-81° C. (176-177*8° E.). Lintner, working with soluble starch, places the optimum temperature at 50-55° C. (122-131° E.). Lintner carefully investigated the effect of heat on diastase itself by dissolving similar quantities of diastase in water, and then heating the various solutions to 55° C. (131° E.) for varying periods of time, and then determining the quantity of each solution requisite to convert the same amount of starch. He obtained the following results : — Of the untreated solution 0*55 c.c. was required. After heating 20 minutes at 55° C., 1*10 c.c. of solution was requisite. „ 40 ,, „ 1*75 c.c. „ ,, ,, 60 ,, ,, 2*22 c.c. ,, were ,, By prolonged subjection to this temperature the diastase Avas much Aveakened ; but, AAfliere starch and its transformation products are present, the diastase does not suffer to a like extent on subjection to this temperature, the strength being reduced by about only half the amount when heated in Avater alone. These results should be compared Avith those of BroAvn and Heron, quoted in paragraph 253, on Nature of Diastase. 233. Effect of Time anl ConcenLation on Diastasis. — Other conditions being the same, the time occupied in producing a given amount of reaction depends on the quantity of diastase present. Concentration AAuthin AAude limits has little effect on the rapidity of diastatic action ; Kjeldahl states that equal quantities of diastase, acting at the same temperature and for the same period of time, effect the same amount of conversion in solutions differing Avidely in degree of concentration. 234. 0th 3r Con litions Favourable anl Inimical to Diastasis. — Kjeldahl states that A^ery minute quantities of sulphuric, hydrochloric, and organic acids accelerate diastasis, but large quantities retard it. Lintner states that sulphuric acid, to the extent of 0*002 per cent., very slightly increases the activity of diastase ; that 0*01 per cent, retards it, and 0*10 per cent, •exercises a destructive action. He also finds that 0*001 per cent, of ammonia retards diastasis, 0*005 per cent, almost, and 0*2 per cent, entirely stops the reaction. The influence, not only of these, but, of course, other sub- stances, depends on their degree of concentration. Speaking generally, acetic and hydrocyanic acids, strychnine, quinine, and the salts of these 134 THE TECHNOLOGY OE BREAD-MAKING. bases, very slightly retard the action of diastase. Alkaline carbonates, dilute caustic alkalies, ammonia, arsenious acid, and magnesia, exercise a somewhat greater retarding influence, depending on the amount of these bodies added. The following bodies completely prevent the action of diastase upon starch — nitric, sulphuric, phosphoric, hydrochloric, oxalic, tartaric, citric, and salicylic acids ; caustic potash, soda, and lime ; copper sulphate and acetate ; mercury chloride, silver nitrate, iron persulphate, alum, and borax. Among antiseptics, formic aldehyde acts energetically, on many of the enzymes. On the other hand — alcohol, ether, chloroform, thymol, creosote, essence of turpentine, cloves, lemon, mustard, etc., exert no retarding influence. In cases where it is desired to suddenly arrest the action of diastase in chemical changes, salicylic acid forms a convenient agent. In 100 c.c. of solution, 0*040 gram of salicylic acid almost destroys the activity of the diastase in 5 c.c. of 40 per cent, malt extract solution, while 0*050 gram completely arrests all action. In any material containing diastase and starch, treatment with hoiling 80 per cent, alcohol completely paralyses any subsequent action of the diastase without gelatinising the starch. Where it is wished to prevent fermentation or putrefaction without retarding diastasis, the addition of small quantities of chloroform or thymol produces the desired effect. Chloroform is conveniently used in the form of chloroform Ab ater, containing 5 c.c. of chloroform to the litre. Toluene may also be employed for the same purpose, and is very slightly if at all harmful to enzymes. 265. Ptyalin and Amylopsin. — Ptyalin is found in human saliva, and at an optimum temperature of 35° C. converts starch paste into dextrin and maltose ; the reaction being identical with that produced by diastase. Ptyalin acts best in a neutral medium, but is but little affected by small amounts of alkali ; a very small quantity of acid, however, arrests its activity, consequently the diastatic action of ptyalin is destroyed on the mixture of food and saliva encountering the acid gastric juice of the stomach. Ptyalin is without effect on cellulose, and hence intact starch granules are not digested by its action. Amylopsin is an enzyme, very similar to ptyalin, found in the pan- creatic juice, where it performs important digestive functions on starchy foods. 266. Raw Grain Diastases. — Earlier observers have pointed out that barley contains more coagulable proteins than does malt, yet fresh barley extract exerts but little diastatic action. Experiments, on which these obser- vations were based, Avere made aa itli starch-paste, but more recent investiga- tions in Avhicli soluble starch Avas employed shoAV that in some cases raAv barley in more actively diastatic than is the green malt prepared from it. Both from barley and Avheat a diastase may be obtained by the same methods as employed for its extraction from malt, that is, by treatment witli £0 per cent, alcohol, subsequent precipitation of the filtered alcoholic extract with absolute alcoliol, and drying in vacuo over sulphuric acid. Lintner and Eckhardt have examined this enzyme in order to determine whether or not it is identical A\'ith malt diastase. For this purpose they took quantities of malt and barley extracts respectively, having the same diastatic value as determined by Lintner ’s method, and subjected soluble starch to their action at varying temperatures. They found that malt diastase had the greatest activity at 50° C., and the most favourable period at 60-55°. RaAV grain diastase, on the other hand, shoAved the greatest activity at 50,. and the most favourable jjeriod at 45-50°. At 4° the raAv grain diastase: ENZYMES AND DIASTATIC ACTION. 135 had as high a reducing power as was possessed by that of malt at 14-5°. The conclusion is that the two forms of diastase are distinct from each other. A more marked and important distinction between these two enzymes is the inability of that from raw grain to effect liquefaction of starch-paste, while if by some other means such liquefaction is effected, raw grain diastase energetically converts the soluble-starch into dextrin and maltose. Brown and Morris notice that the power to liquefy starch-paste and to erode the starch-granule go hand in hand : the observed presence or absence of either property affords safe ground for predicting the presence or absence of the other of the two. But Baker in a paper communicated to the Journal of the Chemical Society in 1902, points out that he was able to completely liquefy starch-paste by barley diastase, in from two to three hours at 50° C., with the production of dextrin and maltose. The raw^ grain diastase is probably an unused residue of an enzyme produced during the previous history of the plant. 267. “ Artificial Diastase ” of Reychler. — ^This worker digested freshly prepared wheat gluten at 30-40° for a few hours with very dilute acids, and thus formed an opalescent solution containing considerable quantities of proteins. The solution is not coagulated by boiling ; it gives a pre- cipitate with a few drops of very dilute potash, soluble in excess. Tincture of guaiacum and h 3 ^drogen peroxide produce an intense blue colouration, but not if the solution has been previously boiled or treated with too much acid. A solution of the gluten from 10 grams of wheat flour in 50 c.c. of dilute acetic acid (1 in 10,000) gives this reaction, which according to Lintner is characteristic of diastase most distinctly. Reychler finds such solutions to possess a similar hydrolytic action to that possessed by diastase, and states that they saccharify starch-pas^e. Reychler finds also that the soluble proteins of wheaten flour give Lintner’s diastase reaction and hydro- l 3 "se starch. Brown and Morris refer to Reychler’s researches on artificial diastase, but point out that the starch transforming powers of the product are essen- tially different from those of malt diastase. Lintner and Eckhardt doubt the existence of Reychler's “ artificial diastase,'" and consider it probably identical with the enzyme of ungerminated grain, and not a conversion- ])roduct of the gluten. This view is based on the fact of a close examination 1 ) 3 " them of the product of the action of dilute acid upon the gluten of wheat. They found the gluten itself to possess diastatic power, which power was greatly increased by the action of acids, the resultant enzyme closely agree- ing with raw grain diastase in its optimum temperature of activity and general character. They conclude that gluten contains a zymogen (enzyme generating substance), from which the artificial diastase is produced by the action of the dilute acid. Egoroff experimented by dissolving gluten in 0*1 per cent, acetic acid, but found no fresh diastase to be formed, and enunciated the opinion that the greater power possessed by these and aqueous solutions of converting starch into maltose is probably due to the develop- ment of a bacterium capable of effecting this transformation. Moritz, and Morris practically endorse Lintner's view on this matter, and suggest the identity of “ artificial diastase " with that of raw grain. There are two points of discrepancy here : first, the enzyme of ungerminated grain is soluble in water, and must be entirely washed away in the preparation of gluten ; second, Reychler distinctly states that his artificial diastase acts upon starch-pas^e, and describes how he prepares the same, namely, by making 2 grams of starch into a “ paste " with 250 c.c. of water. It is interesting to note that as early as 1879, Brown and Heron pointed out that the comparatively inactive proteins of barley, and also wheat. 136 THE TECHNOLOGY OF BREAD-MAKING. may be rendered more efficient as diastatic bodies, after being obtained in solution ; and, consequently, independently of germination. If cold aqueous infusions of barley and wheaten flours, respectively, have a little compressed yeast added to them, and then are allowed to stand for a feiv hours at 30° C., the solution in each case will be found to have considerably increased in diastatic power. A mixture of yeast and cane sugar, under the same conditions, has no action whatever on starch : therefore, growing yeast must be considered as capable of producing certain changes in the inactive proteins of wheat and barley, by means of which they are enabled to act on starch. Such action on starch is, however, caused by the affected proteins, and not by the yeast itself. While saccharomyces act thus on wheat proteins, the schizomycetes not merely confer no diastatic power, but rapidly destroy that which the solutions may have originally possessed. It is possible that the action here ascribed to yeast may be due to acidity formed by its action. The following experiments were undertaken by one of the authors with the view of further elucidating the problem of artificial diastase. A filtered extract of flour was prepared by taking 50 grams of high-class English flour of medium strength, and shaking up with 500 c.c. distilled water, in which had been dissolved 2*5 c.c. of chloroform. (The object of the addition of chloroform w^as the inhibition of any bacterial action, without hindering in any way the effects of diastase.) This solution was allowed to stand for half-an-hour. Altered and divided into two portions — A and B. A. — To portion A, an equal volume of chloroform water was added, and the diastatic value on soluble starch by Lintner’s scale determined immediately in a part of the solution, according to the method described in the analytic section of this work. Another portion of this diluted solution was treated precisely similarly, except that freshly prepared starch paste was substituted for Lintner’s soluble starch. Al. — The diastasic action reckoned on the flour was — With, soluble starch . . . . . . 9*4° Lintner. With starch-paste . . . . . . . . 5 0° ,, B. — To portion B, an equal volume of 0*2 per cent, hydrochloric acid in chloroform water was added, and another pair of similar determinations to those preceding made immediately, with the following results : — Bl. — The diastatic action reckoned on the flour was — With soluble starch With starch-paste less than 2*5° Lintner, there being practically no action whatever. The plain 5 per cent, solution A, and the 5 per cent, solution in 0*1 per cent, hydrochloric acid, B were then digested for twenty hours at 30-35° C., and the diastatic capacity again measured with results as follows : — A2, with soluble-starch . . 14*3° Lintner. ,, with starch paste . . 4*5° ,, B2, with soluble starch vdth starch-paste less than 2*5^ ,, practically no action. In the next place, 25 grams of flour were taken with 250 c.c. chloro- form water, shaken and digested together for twenty hours at 30-35° C., giving preparation C. Another 25 grams were similarly treated with 250 c.c. of 0-1 percent, hydrochloric acid in chloroform water, and digested, being preparation D. After digestion, diastatic measurements were made in the clear filtrate, with the following results : — C, with soluble starch . . 10-0° Lintner. „ with starch-paste . . 4*0° ,, D, with soluble starch „ with starch-paste Digestion with 0*1 per cent, hydrochloric acid not only does no confer less than 2-5^ ENZYMES AND DI ASTATIC ACTION. ’ 137 additional diastatic capacity, but practically inhibits any such power the flour naturally possessed. A series of experiments was next made, in which 0*01 per cent, acetic acid was substituted for the hydrochloric acid. As previously, all solutions were treated with chloroform to prevent any action of bacteria. Of the same flour as before, 25 grams were taken, shaken up Avith 250 c.c. of water, and filtered after half-an-hour standing. An equal volume of 0-02 per cent, acetic acid was added, making a 0-01 per cent, acetic acid solution, called E. Preparation F consisted of 25 grams of flour with 250 c.c. of 0 01 per cent, acetic acid, shaken up and not filtered. These Avere digested for tAventy hours at 30-35° C., and the mixture F filtered. In each, diastase deter- minations AA’ere then made, both Avitli soluble starch and starch paste. E, Avitli soluble starch ,, AA'ith starch paste F, AAuth soluble starch ,, AA'ith starch paste 26-3° Lintner. 15.1° 29*4° 16*6° These experiments shoAv that very dilute acid (O-Ol per cent, acetic) considerably increases diastatic activity, even Avlien any possible bacterial action is prevented, by the presence of chloroform, throughout the Avhole course of the experiment. Comparing A 2, AAiiich Avas a plain solution of the flour, digested for tAventy hours after filtration, Avith E, Avhich Avas a solution of the same strength, acidulated to the extent of 0*01 per cent, with acetic acid, after filtration but before digestion, there is an increase in diastatic capacity from 14*3° to 26*3° Lintner on soluble starch, and from 4*5° to 15*1° on starch paste. The diastatic activity of the proteins actually in solution has been definitely increased by this treatment. It should be noticed also that the particular diastase present is not only capable of con- verting soluble starch, but also hydrolyses starch paste. In D and F, the Avhole flour and water, and dilute acid respectively, Avere digested together before filtration. Again there is an increase in diastatic capacity. From a comparison of E and F, it AA^ould seem that very little of the increased diastatic action is due to any change in the insoluble protein of the flour, as the F results are only slightly in excess of those in E. It is curious to note that in A2 and C, both experiments with plain Avater, diges- tion after filtration yields a more active product than digestion before filtration. 268. Invertase. — ^Although diastase is unable to carry the hydrolysis of starch further than into maltose, yet, as already stated, there is evidence of malt extract containing an enzyme capable of converting cane-sugar into glu- cose. BroAvn and Heron adduce experimental proof of this point in a contribu- tion to the Journal of the Chemical Society, Vol. XXXV, 1879, page 609 ; they show that a cane-sugar solution, after being digested for 16 hours at 55° C. Avith cold water extract of malt, contained £0*4 per cent, of glucose. If, on the other hand, the malt extract were previously boiled for 15 minutes, the percentage of invert sugar Avas reduced to 0*2 per cent. This enzyme has been termed zymase, but is noAV knoAvn as invertase, the former name, being applied to another enzyme, Avhich Avill subsequently be described. For practical purposes the principal source of invertase is beer-yeast, from Avhich it may be separated in a fairly concentrated form. O’Sullivan and Tompson recommend for this purpose that sound breAvers’ yeast be pressed, and then kept at the ordinary temperature for a month or tv^o, during AA'hich time it does not undergo putrefaction, but changes into a heavy yellow liquid. On filtering, this yields a clear solution of high hydrolytic poAver, contain- ing all the invertase of the yeast in solution. This liquid has a specific 138 THE TECHNOLOGY OF BREAD-MAKING. gravity of about lOSO, and is termed ‘‘ yeast liquor ” by O’Sullivan emd Tompson. This liquor remains for a long time unaltered, except for a darken- ing of colour. On adding spirit to yeast liquor till it contains 47 per cent, of alcohol, the invertase is precipitated, and may be washed with spirit of the same strength and dried in vacuo, or preserved as a solution by extracting the precipitate with 10 per cent, alcohol, and filtering, when the filtrate con- tains the invertase. Invertase acts rapidly on cane-sugar according to the equation : — ■ C12H22O11 = C6H12O6 "I- C6H12O6. Cane-sugar. Glucose. Fructose. This speed of inversion increases rapidly with the temperature until 55- 60° is reached. At 65° invertase is slowly, and at 75° immediately destroyed. Minute quantities of sulphuric acid are exceedingly favourable to the action, but a slight increase of acidity beyond the favourable point is very detri- mental. A sample of invertase which had produced inversion of 100,000 times its own weight of cane-sugar was still active ; and further, invertase itself is not injured or destroyed by its action on cane-sugar. There is evidently no limit, therefore, to the amount of sugar which can be hydrolysed by a given amount of invertase. The caustic alkalies, even in very small proportions, are instantly and irretrievably destructive of invertase. Inver- tase is without action on starch, dextrin, maltose, glucose, fructose and gum. Osborne has prepared invertase in an exceedingly pure form, and finds it to give none of the protein reactions, except precipitation by copper sul- phate, lead acetate, and phospho-tungstic acid ; though it gave Millon’s, the xanthoprotein, and biuret reactions very faintly. He therefore con- cludes that it is not protein in nature. 269. Maltase. — In addition to invertase, Lintner regards yeast as containing another and distinct enzyme, to which has been given the name of maltase. This body possesses the power of changing maltose into glucose. 270. Intestinal Invertase. — The secretions of the small intestines contain an enzyme allied to the invertase of beer-yeast, inasmuch as it inverts cane- sugar into glucose and fructose ; it also inverts maltose into glucose, thus differing from the invertase of yeast, which has no action on maltose. Brown and Heron state that it acts on starch, but Halliburton is of opinion that the bulk of evidence is against the presence of any such diastatic action. 271. Pepsin, or Peptasc, and Trypsin. — Collectively, the fluids of the stomach are known as gastric juice, and contain an active proteolytic enzyme termed pepsin. Pepsin may be obtained from the mucous membrane of the stomach by extraction with glycerin, in which pepsin is soluble. The pepsin is precipitated from its glycerin solution by alcohol, dissolved in water and freed from salts and peptones by dialysis. Pepsin is soluble in water to a mucous liquid, but is insoluble in alcohol or ether. Pepsin has been pre- pared by Pekelharing in a comparatively pure state ; he finds it to give the majority of protein reactions, but not to contain phosphorus, thus negativ- ing any possibility of its belonging to the nucleo-proteins. In the presence of an acid, preferably hydrochloric, pepsin attacks and rapidly dissolves insoluble protein substances, as the white of hard-boiled eggs or lean beef, converting them into peptones. Pepsin is most active at about 40° C., and loses its power on exposure to 57-58°. The acid condition is necessary to its action, and is supplied in the gastric juice by the presence of hydrochloric acid, which in the gastric juice obtained from the human stomach amounts to 0 02 per cent., and in that of the dog to 0*30 per cent. The energy of pepsin is impaired, and at last arrested by the peptones produced. Dried pepsin ENZYMES AND DIASTATIC ACTION. 139 may now be obtained as an article of commerce, being prepared by drying under 100° F. the fresh mucous lining of the stomach of the pig, sheep, or calf. In accordance with the scheme of nomenclature in which the names of the enzymes end in ase, the name of this body is frequently written peptase. Trypsin occurs in the pancreatic juice, and is allied in its general behaviour to pepsin, possessing like it the power of converting proteins into peptones, It differs, however, in the fact that it acts best in an alkaline medium, and less energetically in neutral or slightly acid solutions. The action is arrested by the presence of hydrochloric acid in excess. 272. Proteolytic Enzyme of Resting and Germinating Seeds. — Seeds generally appear to contain a proteolytic enzyme in the form of a zymogen, which during the act of germination becomes converted into an active en- zyme, termed protease. This body converts the proteins of the seed into pep- tones, leucin, and tyrosin. Malt extract exerts a marked physical and chemical effect on the proteins of flour during bread fermentation, a result due to the presence of a proteolytic enzyme, or form of protease. 273. Zymase. — Recent researches by Buchner and others, (Berichte d. DeutscJi. cliem. Ges., 1897), have shown that when yeast is ground up with sand and kieselguhr, and then subjected to filtration under hydraulic pres- sure, a liquid is obtained which is free from yeast cells, and yet is capable of converting sugar in solution into alcohol and carbon dioxide. The chemical action commences in something under an hour and continues regularly for some days. By treatment with alcohol, an active principle can be separated from the yeast filtrate. Buchner proposed the name zymase for this sub- stance, and has proved its action to be due neither to yeast cells nor to frag- ments of yeast protoplasm contained in the liquid. Zymase is, therefore, to be regarded as a definite member of the enzyme group. 274. Other Enzymes. — -Among other enzymes mentioned in the classified list previously given, a word should be said about those included in the group of coagulative enzymes. The coagulation of blood on leaving the body is due to an enzyme ; so also is that of muscle at death, in the case of the stiffening termed rigor mortis, known in this instance as the myosin- ferment or enzyme. Interest attaches to this, as the animal analogue of Weyl and Bischoff's hypothetical myosin, to which they ascribe the formation of gluten in the doughing of wheaten flour. Space does not permit any further reference to the emulsive and steato- lytic enzymes. Details of Applied Hydrolysis. 275. Empirical Statement of Hydrolysis of Starch. — It will be seen that the formulae, representing the probable constitution of the molecules, are much more complex than the empirical formulae respectively of starch and dextrin. The following empirical equation represents in the simplest possible manner the above reaction ; it must not, however, be viewed as representing the true nature of the molecular change involved : — (CsHioOsjs + 2 H 2 O = CeHioOs + 2Ci2H220n. Soluble Starch. Water. Dextrin. Maltose. 276. Hydrolysis of Cane-Sugar. — ^This operation is slowly effected by the action of malt extract, or even by prolonged boiling with water, which effects the same change more or less completely. At ordinary tempera- tures, dilute sulphuric and hydrochloric acids are capable of slowly in- verting cane-sugar ; at temperatures of from 65° to 70° C. the hydrolysis .140 THE TECHNOLOGY OF BREAD-MAKING. occurs with extreme rapidity. For laboratory purposes, complete inversion is effected by adding to the moderately strong sugar solution one-tenth its volume of strong hydrochloric acid, and then heating the mixture in a water-bath until the temperature reaches about 68° C. The change con- sists of the cane-sugar molecule splitting up into two molecules of glucose, the one being dextro and the other laevo-rotary — C12H22O10 + H2O = C6H12O6 -h C6H12O6. Cane-Sugar. Water. Dextro-glucose. Lsevo-glucose. Invertase also effects this change, and apparently is likely to be em- ployed commercially for the purpose. O’Sullivan recommends its employ- ment in the laboratory for the hydrolysis of cane-sugar as a step towards its analytic estimation. 277. — Hydrolysis of Dextrin. — By the action of acids, and also of malt extract, this body may be entirely converted into maltose : the nature of the chemical change has been described when treating of the hydrolysis of starch. Under ordinary conditions, neither invertase nor yeast itself is capable of effecting the hydrolysis of dextrin. 278. Hydrolysis of Maltodextrin. — This change is readily effected by the action of malt extract, but not by either invertase or yeast. 279. Hydrolysis of Maltose . — Maltose is a more stable sugar than is cane-sugar : dilute acids effect its conversion with slowness ; thus a maltose solution may be boiled for some minutes with dilute sulphuric acid without undergoing change. Complete inversion results from keeping the solution at a temperature of 100° C. for some six or eight hours. The principal product of inversion is glucose. As has been previously stated, malt extract has no hydrolysing action on maltose. Invertase also is without action on maltose, but maltase effects its hydrolysis. 280. Composition of Malt. — Prior to dealing with the saccharification of malt, some information should be given of its composition. Treatment of the general questions of the transformation of barley into malt must be postponed until the subject of the physiology of grain life is being dis- cussed. Malts differ from barley in that the protein constituents show proofs of considerable degradation. Hilger and Van der Becke have exam- ined barley, barley softened by steeping in water, fresh or green malt (un- kilned), and kiln-dried malt. The following table gives the percentage of nitrogen, and of the various nitrogenous constituents : — Nitrogeneous Constituents of Barley and Malt. Barley. Softened Barley. Fresh Malt. Dried Malt. Total Nitrogen 1-801 1-750 1-751 1-542 Nitrogen of Insoluble constitu- ents . . 1-6789 1-6853 1-372 1-165 Nitrogen as Albumin (soluble) 0-0600 0-0354 0-1571 0-1194 . as Peptone . . 0-0046 0-0009 0-0058 0-0233 ,, as Ammonium Salts 0-0169 — 0-0290 0-0057 ,, as Amino-acids 0-0417 0-0294 0-1417 0-2257 ,, as Amides . . — 0-0505 0-0029 ENZYMES AND DIASTATIC ACTION. 141 It will be seen that the insoluble proteins have diminished in quantity, while the albumin has increased ; so also have the products of further degradation, peptone, amino-acids, and amides. The starch in barley also suffers considerable diminution ; Brown and Morris found the quantities of starch in barley before and after germination to amount to Starch ix 1000 Corns. i Starch in Barley Starch in Barley after before Germination. Six Days’ Germination. Loss of Starch. ' Expt. 1 9 >5 w • • 20*0552 grams. 15*4398 gTams. 19*9158 „ 15*3836 „ 4-6154 grams. 4-5522 „ Taking the mean of the two experiments, 22*5 per cent, of the starch has disappeared. A portion of this has been dissipated as carbon dioxide gas, a portion will have constituted the material from which the new parts of the plant have been formed, while a third portion will have been changed' into sugars, which remain in the malt at the end of its manufacture. The increase of sugars is well shown in the following table, which gives in per- centages the results of analyses of barley before and after germination, by O’Sullivan. Sugars in Barley before and after Germination. i i i ' i SUG.\RS. j 1 No. 1 Barley. ! No. 2 Barley. 1 Before ! Germination. After Germination. Before Germination. After Germination. 1 Sucrose (Cane-Sugar) . . 0-9 4*5 ' 1*39 4*5 Maltose . . ! (1-2 1 (1*98 i Dextrose. . 1 U-1 ’ 3*1 ' 0*62 1*57 Laevulose . . i ) ; 0*2 1 j lo*71 It will be seen that cane-sugar forms a very notable constituent of malt, and also that the other sugars are present in large quantity. The percentage of acid considerably increases in grain during malt- ing ; assuming acidity to be due to lactic acid, Belohoubek gives the fol- lowing : — Barley . . . . . . . . . . 0*338 per cent, as lactic acid. Green Malt . . . . . . . . 0*590 ,, ,, , ,, Kilned Malt 0*942 ,, „ ,, In English malts, however, the percentage of acid is considerably less than this, being usually about 0*2 per cent. ; so much as 0*4 per cent, is viewed as an indication of unsoundness. Although the acidity of malt is usually returned as lactic acid, a considerable amount is due to the presence of acid phosphates. • The following table gives the approximate composition of malt, based principally on analyses by O’Sullivan : — 142 THE TECHNOLOGY OF BREAD-MAKING. Approximate Composition of Malt. Per Cent, Per Cent. Starch . . 4400 to 50-00 Sugars . . 9-00 5) 16-00 ,, These include Sucrose, from 4-50 ) 1 ,, Maltose, ,, 1*20 1 16-00 ,, Dextrose, ,, L65 I ^ JJ ,, Lsevulose, ,, Unfer men table Carbohydrates, not Dextrin 0-20 1 1 5-00 55 7-00 Cellular Matter (Cellulose) . . 1000 55 12-00 Proteins, soluble in cold water 30 J 5 4-50 ,, insoluble ,, 8-00 55 10-00 Fat 1-50 5 5 2-00 Ash 1-90 5 5 2-60 Water . . 2*50 55 7-00 Acid reckoned as Lactic Acid 0-20 5 5 0-40 281. Saccharification of Malt during the Mashing Process. — ^This process is of interest both from the technical point of view, as being largely used by the baker, and also scientifically, as representing an important example of hydrolysis by malt extract. Malt contains the active hydrolysing prin- ciple, diastase, and also from 44 to 50 per cent, of starch. In the operation of malting, the walls of the starch granules get more or less ruptured and fissured ; hence the interior granulose is at the outset somewhat exposed to the action of the diastase. As a first step toward the preparation of beer, the brewer treats his ground malt with water at a temperature of from 65-5° C. (150° F) to 71 -1° C. (160° F.). This results in the conversion of the starch present into dextrin and maltose. This operation he terms “ mashing.” The first change is that the starch becomes gelatinised, and is then freely susceptible to the action of diastase. At temperatures below the gelatinising point of starch, diastasis also proceeds, but some- what more slowly (comp. Lintner's table, par. 257). At a temperature of about 60° C. (140° F.) almost all the starch, and also the amyloins, will have disappeared in about twenty minutes ; this point may be ascertained by taking out a drop of the liquid and testing it with iodine. An increase of temperature weakens the action of the diastase ; hence a mashing made at 60° C. (140° F.) yields in two hours, for the same malt, about 7 per cent, more dextrin and maltose than when mashed at 76*6° C. (170° F.) Further, as might be expected from the results already mentioned, the proportion of dextrin is much greater in the mashing made at 76*6° C. than at 60° C. The duration of the mashing operation has also an influence on the amount of dextrin and maltose produced. With a temperature of 62*7° C. (145° F.) most of the starch is converted into dextrin and maltose within thirty minutes, but for some time after, the yield of these continues to slightly increase. The proportion of maltose to dextrin also becomes higher with a longer mashing. The following is the result of an experiment by Graham : — Length of Percentage of Percentage of Total percentage Ratio of Maltose Mashing. Maltose. ^ Dextrin. of Maltose & Dextrin. to Dextrin. J hour. 48-60 14-61 63-21 3-3 : 1 1 „ 52-35 12-23 64-61 4-2 : 1 2 hours. 53-56 11-39 64-95 4-7 : 1 54-60 11-05 64-65 4-9 : 1 7 „ 61-47 3-53 65-00 17-4 : 1 It will be seen that by far the greatest proportion of the transformation is effected within the half-hour, while for all practical purposes the hydrolysis is completed within two hours at the furthest. ENZYMES AND DIASTATIC ACTION. 143 282. Mashing Malt together with Unmalted Grain. — ^The diastase of good malt is not merely capable of saccharifying its own starch, but is competent also to hydrolyse in addition considerable quantities of starch from other sources ; hence, in brewing operations, malt is frequently mixed with flour from other cereals, either rice or maize being commonly chosen. The diastase of the malt saccharifies the whole of the starch present ; but with the proportion of malt unduly low, the ratio of maltose to dextrin produced is comparatively small. Experimental Work. 283. Hydrolysis of Starch. — ^Mix 10 grams of starch with 200 c.c. of water, and gelatinise by placing in the hot water-bath. Take 50 c.c. of this solution and add to them 10 c.c. of five per cent, sulphuric acid. Main- tain at a temperature of 100° C. until a few drops, taken out with a glass rod or tube, and placed on a porcelain tile, give no blue colouration on addition of iodine. To the solution add precipitated calcium carbonate, or powdered marble, until it ceases to produce effervescence. Allow the precipitate to subside, and filter ; taste the clear solution, notice its sweet- ness. Test a portion of this filtered solution with Fehling’s solution, a red precipitate is produced, showing that either maltose or glucose is present. To a test tube, containing another portion of the original starch solu- tion, add some saliva, and stand it in a water-bath at a temperature of about 40° C. for some time : notice that the solution becomes more limpid, and ultimately that it gives no starch reaction, on a few drops being taken out and treated with iodine. Test now for maltose, by means of Fehling's solution ; a red precipitate is produced. As a complement to this experi- ment, boil some corn-flour and water, allow' the paste to cool, place a spoon- ful in the mouth, retaining it there for some fifty or sixty seconds, and mixing it w ith saliva by means of the tongue : notice that the paste becomes limpid, and acquires a sweet taste. Take some fresh compressed yeast, mix a little wdth some of the starch solution and place in the w'ater-bath at 40° C. Notice that after several hours the starch remains unaltered, giving a blue colouration with iodine, and little or no reaction wdth Fehling’s solution. Prepare some “ yeast- W'ater by shaking up about 50 grams of the compressed yeast wdth 150 c.c. of cold water ; let this stand for from four to six hours, shaking occa- sionally, then allow to subside and filter the supernatant liquid. Treat some starch solution wdth this yeast-w'ater in the same w^ay as with the yeast itself : notice that this also causes no alteration in the starch. Make an aqueous extract of malt, as described in paragraph 255. Take some sound wheat starch, examine it under the microscope, to see that none of the granules are fissured or cracked. Add some of the malt extract to a portion of this starch, and allow" it to remain for some hours at a tem- perature of 20° C. Maintain another similarly prepared sample at a tem- perature of 40° C. for from six to tw'elve hours. At intervals from the time of starting the experiment, and at the end of the time, examine the starch in each case carefully under the microscope, in order to see w'hether any of the granules show signs of cracking or pitting. Make a comparative series of experiments on potato starch. In every experiment, at the end test the starch granules w ith iodine, in order to see w'hether they still give the starch reaction. Shake up some starch wdth w'ater, and filter : notice that the clear filtrate gives no reaction wdth iodine. Rub a little of the starch in a mor- tar with powdered glass ; this cuts the cellulose envelopes. Shake up with W"ater, and filter ; to the clear filtrate add iodine solution : a blue 144 THE TECHNOLOGY OE BREAD-MAKING. colouration shows the presence of soluble starch. To some of the bruised starch add malt extract, and allow to stand for twenty-four hours at 20° or 25° C., examine under the microscope, and notice that much of the interior of the cells is dissolved away. Treat a little with iodine, and examine under the microscope in order to determine how much unaltered starch remains. Make some starch paste, as described in paragraph 259 ; treat it with malt extract as there mentioned, and at intervals of a minute take out a drop of the solution by means of a glass rod, and test with iodine on a porcelain tile. Note the time when the starch and the amyloins dis- appear. Make a series of similar experiments with varying temperatures, rising by 10° C. at a time, from 15° C. to the point at which diastasis ceases. The quantities of solution should be measured ; and in each case, both the starch and the malt extract solutions should be allowed to stand in the water-bath, regulated to the desired temperature, until both have acquired that temperature, then mix the two and note the time. If desired, the bath may be regulated for this experiment by means of the regulator described and figured in Chapter XI. ; in that case it is not absolutely necessary to get the temperature nearer than a degree, but the exact tem- perature, as read by a thermometer, should be noted. Make a cold aqueous infusion of bran or pollard in the same way as described for malt, and treat starch solution with it, as was done with the malt extract, both in the cold and at higher temperatures. If separated wheat germ is obtainable, make a similar series of experiments with that substance. 284. Hydrolysis of Cane-sugar. — ^Mix cane-sugar solution with strong hydrochloric acid, and heat to 68° or 70° C., as described in paragraph 276. After hydrolysis, test for reducing sugars by Eehling's solution. To another portion of the cane-sugar solution add some yeast-water, and main- tain for three or four hours at 40° C., after which test for maltose or glucose by means of .Eehling’s solution. 285. Mashing of Malt. — Take 100 grams of ground malt, and mix with 500 c.c. of water at 60° C. in a large beaker ; weigh the beaker and its contents, and place it in a water-bath at 60° C. Stir occasionally, and from time to time take out small quantities of the well-stirred liquid on the end of a glass rod, and test for starch by iodine solution. Note how long it is before the starch disappears ; as soon as iodine produces no blue reaction, wipe the outside of the beaker, place it in the balance, and add distilled water until that lost by evaporation has been replaced : when this point is reached the beaker weighs just the same as before being placed in the bath. Then filter the clear solution, cool rapidly to 15° C., and take the density by means of a hydrometer. The method of using the hydrometer, and the conclusions to be drawn from the density of the wort, are described in the paragraph on “ Specific Gravity of Worts '' in Chapter XII Make similar masliings at the temperatures respectively of 50° and 70° C. ; note in each case the time requisite for saccharification, and the density of the wort. For the different experiments both the mashing liquor and the bath must be regulated to the temperature desired. 286. Substances inimical to Diastasis. — Prepare some starch solution and malt extract as in paragraph 283. To a portion of the malt extract add a small quantity of caustic potash, and note the time it takes to sac- charify the starch, both starch and malt being used in the same proportions as before. Make similar tests with solutions of sulphuric, tartaric and salicylic acids ; lime, copper, sulphate, alum, borax, alcohol, and essence of turpentine. CHAPTER IX. FERMENTATION. 287. Origin of Term. — When a little of the substance called yeast is added to some wort (i.e., the sweet liquid produced by the infusion of malt with warm water), at a temperature of about 18° C., it induces a most remarkable change. The quiescent liquid after a time becomes filled \vith bubbles ; these rise to the surface and form a scum there ; as the action proceeds these bubbles are produced with increased rapidity. Their continuous ascension gives the liquid a seething or boiling appearance, and from this has arisen the application of the term “ fermentation "" to tliis peculiar phenomenon ; that word being derived from the Latin ferveo, I boil. Fermentation results in a disappearance of the maltose present in tlie wort, together with the production of alcohol and carbon dioxide gas. The former remains in the liquid ; the latter rises to the surface and causes the before-mentioned boiling appearance. The carbon dioxide bubbles carry with them to the surface a peculiar sticky “ scum ” ; this substance has received the name of “ Yeast,” and on being added to a fresh quantity of wort, is capable of setting up fermentation therein. During the fermentation of wort, the quantity of this “ scum ” produced is many times in excess of that in the first place added to the wort. 288. History of the Views held of the Nature of Fermentation. — The earlier researches and published articles on fermentation regard that change as one of spontaneous decay. Yeast, with which fermentation is associated, vas viewed as a peculiar condition which nitrogenous matter assumed during one of the phases of its decomposition. That in this state it was able to set up fermentation in a liquid, which was not at the time fermenting, was noticed as a remarkable property of yeast, which nevertheless was still considered as only nitrogenous matter in a particular stage of chemical change. One of these earlier views ascribed alcoholic fermentation to a vegeto-animal substance which resided in grapes as well as in corn. When the grapes were crushed, and the flour moistened, this fermentative agent commenced to produce active change. The body thus capable of inducing fermentation was termed a “ ferment.” The next step in investigation of this matter was that of Thenard, who observed that the ferment con- tained nitrogen, and that in distillation ammonia was yielded ; he there- fore ascribed an animal nature to the ferment. (It should be explained that the older chemists were in the habit of looking on nitrogenous organic matter as animal, and the non-nitrogenous as vegetable ; no reference is intended to the peculiar organic structure of the ferment.) Opinion had settled down to the view that yeast was an immediate principle of plants, when the microscope, which had become such an important factor in scientific research, was brought to bear on the construction of yeast. Leuwenhoeck had, as early as 1680, discovered that yeast consisted of minute granules ; but it was only in 1836 that de Latour again called 146 THE TECHNOLOGY OF BREAD-MAKING. attention to its microscopic structure. It was observed by him that yeast was a mass of little cells, and, further, that these were capable of repro- duction by a process of budding. “ Yeast, therefore,"’ said the discoverer, “ must be an organism which probably, by some effect of its growth, effects the decomposition of sugar into alcohol and carbon dioxide.” This newly discovered form of life was, after some discussion, placed among the fungi, a new genus being created for it by Meyen, to which was given the name of Saccharomyces. This view attracted considerable attention from scientists, and although the basis of that now almost universally accepted, encountered most uncom- promising opposition. Prominent among its antagonists was Liebig, who in 1839 argued yeast to be a lifeless albuminous substance, and held that the cause of fermentation is the internal molecular motion which a body, in the course of decomposition, communicates to other matter in which the elements are connected by a very feeble affinity. Said Liebig, “yeast, and in general all animal and vegetable matter in a state of putre- faction, wiU communicate to other bodies the condition of decomposition in which they are themselves placed ; the motion which is given to their own elements by the disturbance of equilibrium is also communicated to the elements of the bodies which come in contact with them.” Ampli- fying this theory, Liebig asserted that the protein bodies decomposed spontaneously, and the molecular disturbance resulting from this decom- position effected also the decomposition of such bodies as sugar, when placed in contact with the decomposing proteins. For some years, de Latour’s, or the vital hypothesis, Liebig’s, or the mechanical hypothesis, and other views based on catalytic action, were three contending theories of fermentation. The next great step was that the whole problem of fermentation received a most careful and exhaustive examination at the hands of Pasteur, who in 1857 gave as his “most decided opinion” that “the chemical action of fermentation is essentially a correlative phenomenon of a vital act, beginning and ending with it. I think that there is never any alcoholic fermentation without there being at the same time organisation, development, multiplication of globules, or the continued consecutive life of globules already formed.” In 1870, Liebig published a long memoir on fermentation, in which he admitted that yeast was a living organism, but stiU maintained that fermentation was a mechanical act, pointing out that the quantity of sugar decomposed by yeast was out of all proportion to the amount of carbohydrate (cellulose) which the yeast had assimilated. To quote his own words — “ Yeast consists of vegetable cells which develop and multiply in a solution containing sugar, and an albuminate, or a substance resulting from an albuminate ... It is possible that the physiological process stands in no other relation to the process of fermentation than that by means of it a substance is formed in the living cell, which, by an action peculiar to itself — resembling that of emulsin on salicin or amygdalin (enzyme) — determines the decomposition of sugar and other organic mole- cules.” The admission of the physiological action of yeast being even indirectly associated with the decomposition of sugars during fermentation was an enormous concession by Liebig. Writing in 1895, one of the authors summarised the then position in the following terms : — “ A study of the action of enzymes shows that Liebig’s position is partly justified : invertase can be separated from yeast, and afterwards is fully capable of performing its functions of inverting cane-sugar, but such study does not lead us to observe a sufficiently close relation- .ship between enzymic action and alcoholic fermentation as to prove ” FERMENTATION. 147 their identity. Still in many respects there is great similar it}^ At present there is the marked distinction that alcoholic fermentation is inseparable from life, while enzymosis occurs in the absolute absence of living organisms. As a result of prolonged research and investigation the vitalistic theory of fermentation is now practically universally accepted. “ A careful study of the preceding sentence shows, however, that the statement of fermentation being a vitalistic act is not an explanation of fermentation. Granted that fermentation is a concomitant of vitality (i.e., is due in some way to life), there must be some agent through which life acts in producing the chemical change of sugar into alcohol and carbon dioxide. In itself, this change is no more striking than the change of starch, by diastase, into dextrin and maltose ; yet we know that diastase, although a direct product of life, is a soluble and abso- lutely unorganised body. Is there any such unorganised body through Avhich yeast acts when effecting the decomposition of sugar ? The answer is — no such substance has as yet been detected, to say nothing of its isolation. “ Hoppe-Seyler and Halliburton incline to the hypothesis that the difference between organised ferment action and that of enzymes is this : an organised ferment is one which does not leave the living cell during the progress of the fermentation ; an unorganised ferment, or onzyme, is one which is shed out from the cells, and then exerts its activity. Probably the chemical nature of the ferment is in the two cases the same, or nearly the same. “ So far as we are acquainted with the nature of enzymes, they are either identical with, or closely allied to, the proteins. If fermentation be due to an enzyme-like body within the living cell, that body is of the nature of living proteins — like other proteins they are indiffusible, and consequently are not discoverable outside the cell wall. “ Like all living things, their properties during life are different from those after death ; this readily accounts for the fact that, with a few excep- tions, they are not discoverable inside the cell wall after the cell has been killed by alcohol. The few exceptions are probably those which are more robust, and withstand the action of alcohol better.'’ In this way does Halliburton endeavour to explain the difference between organised ferments and enzymes. The explanation, unfortunately, does not cover the whole problem. Even the more robust “ ferments " cannot be said to have life in the ordinary sense of the term when extracted by dilute alcohol, and obtained in a state of perfect solution. Independently of any organism, the enzymes are able to prosecute their functions ; but alcoholic fermentation cannot be induced by any substance contained by the yeast cell, unless that cell be living. If the protoplasm of yeast be liberated by crushing the cells, such extracted protoplasm does not cause fermentation. There is little doubt that fermentation does take place within the cell, and is in some way caused by some property of living protein, hut it is an essential that the protein he alive, and a part of a living organism. This much may be conceded, that probably the living protein acts in a more or less similar manner to an enzyme. In view of this it is interesting to note the agreement rather than the differences between the views promulgated by the illustrious savants Liebig and Pasteur ; but, after all, there is the broad line of demarcation — enzymosis is independent of living organisms, while “ fermentation is essentially a correlative phenomenon of a vital act, beginning and ending with it.” The discussion of the nature of the vital act producing fermentation does not dispose of the fact of its being vital.” 148 THE TECHNOLOGY OF BREAD-MAKING. 289. Zymase Theory of Fermentation. — In the light of subsequent researches these views must now be considerably modified. In 1897, Buchner made the first announcement of the discovery of zymase, which is referred to and described in paragraph 273. This is an enzyme, secreted within the yeast cell, but which may be extracted from it and apart alto- gether from the living organism can effect the decomposition of glucose into alcohol and carbon dioxide. Work in this field of investigation was carried still further by the researches of Buchner, Rapp, Albert, Harden, and others, the results of which have been published in a series of papers extending from 1897 to 1905. The net result of such investigation is to confirm the view that zymase is an enzyme, and effects the decomposition of glucose independently of vital functions of the living cell. Of this, a striking proof is afforded by some experiments of Albert, who killed yeast by subjecting it to the action of a mixture of absolute alcohol and ether. The yeast was then dried and still possessed the power of exciting alcoholic fermentation. Consequent on the indiffusibility of the protein eontents of the cell, no fermentative enzyme can be extracted from this unbroken yeast by the action of water. But if the eells be broken up, an active extract may be obtained. A dried preparation of zymase has been patented, of which it is said that from 5 to 10 per cent, of it is capable of raising dough. Zymase has no reproductive action, and possesses a fermentative power which is only a minute fraction of that of yeast. It would seem that zymase is destroyed during fermentation almost immediately as formed, so that no accumulated store of the enzyme is found in yeast. Harden believes that zymase alone is incapable of acting on sugar, and that yeast contains in addition another substance which stimulates the zymase into activity. In his opinion neither of these alone sets up fermentation in sugar solutions, but the two acting in conjunction effect the decomposition. In accordance with the zymase theory of fermentation, sugar finds its way by diffusion into the interior of the living cell ; it is then changed into glucose by the action of invertase ; then the decomposition into alcohol and carbon dioxide is effected by the enzyme zymase secreted by the cell within itself. The zymase is being continually formed and destroyed in the act of inducing fermentation. The discovery of zymase is the discovery of the agent by w'hich yeast effects the decomposition of sugar ; but such discovery leads us very little beyond the view of Pasteur that “ the chemical action of fermentation is essentially a correlative phenomenon of a vital act,’' since tJie zymase is produced as a function of the life of yeast, and is destroyed in the act of fermentation. 290. Definition of Fermentation. — The particular action produced by yeast on wort, and also on the sweet “must,” or expressed juice of the grape, was found on investigation to be but one of many chemical actions whicli are associated with the life, growth, and development of microscopic organisms. Among these may be cited the souring of milk, also of wine into vinegar, and likewise the changes occurring during putrefaction. Con- sequently tlie term fermentation is no longer used in its original sense, as signifying a condition resulting in a peculiar seething or boiling appear- ance, but is applied to that group of chemical changes which are, in Pasteur’s words, “ correlative phenomena of vital acts.” Subject to the limitations explained in the preceding paragraph, and used in its extended sense, fermentation may be defined as a generic term applied to that group of chemical changes which are consequent on the life and development of certain minute micrc- copic organisms. In the chapter on the proteins, it was stated that putrefaction is regarded as a species of fermentation : equally, with the conversion of maltose into FERMENTATION. 149 alcohol by yeast, it is a change induced by living organisms. This of itself is a conclusive answer to Liebig’s earlier position, that fermentation is a secondary result of the spontaneous decomposition of proteins, inasmuch as that, in the absence of minute organisms, the decomposition of proteins does not occur : it is consequently not spontaneous, and therefore fer- mentation cannot be considered as a process dependent on spontaneous decomposition. 291. Modern Theory of Fermentation. — The following is a short state- ment of this theory. Maltose, proteins, and other fermentable substances do not decompose of themselves, even when subjected to favourable con- ditions of moisture, warmth, etc., provided that fermenting organisms and their immediate products are rigorously excluded. These, on their introduction, thrive and multiply ; taking the nourishment requisite for their development from the substance which is fermented. A special feature characteristic of fermentation is that the amount of matter consumed and changed into other compounds is excessively great, compared with the size and weight of the consuming organisms ; consequently a very few yeast globules decompose very many times their weight of sugar, and produce a relatively large quantity of alcohol and carbon dioxide. No very clear reason has as yet been given for this char- acteristic of fermentation, but one explanation is that the decomposition of sugar furnishes not only material for the growth and development of cells, but also the heat necessary for the continuance of yeast life. It is this double function of sugar in fermentation which causes the enormous consumption of that compound. Fermentation is thus seen to be like enzymosis in that a small quantity of the active agents induces chemical change in much larger quantities of material ; but fer- mentation goes further, inasmuch as the quantity of fermenting agent itself also increases during its continuance. In alcoholic fermentation then, yeast, in order to obtain heat and nour- ishment, attacks glucose or maltose, and excretes or voids carbon dioxide gas, alcohol, and small quantities of other bodies. The assimilative power of yeast is limited to converting the sugar into these substances, which then become, so far as it is concerned, waste products. Other organisms attack the proteins and produce butyric acid and other compounds. Each particular organism has its special products of fermentation. 292. Experimental Basis of Modern Theory. — It is scarcely within the scope of the present Avork to trace step by step the nature of the various researches which have led to the adoption of the theory just explained. Briefly stated, the first and most important point is that a liquid free from ferment organisms, or their germs does not undergo fermentation. In proof of this point, liquids were placed in flasks or tubes, the necks of Avhicli were tightly plugged with cotton avooI. The liquids Avere then boiled for some time ; the heat destroyed any organisms that might have been present in the liquids or the avooI. As the flasks cooled, the contained steam condensed ; and air forced its Avay through the cotton avooI, AALich acted as a filter and stopped off any germs that might have been floating in the air. Hay and beef infusions, must, Avort, urine, and other liquids, on being treated in this manner, may be kept for any length of time AAuth- out undergoing fermentation or putrefaction. That the resistance to fermentation is due to the absence of fermenting organisms, and not to the liquids having been so changed by boiling as to be unfit for fermen- tation to proceed, is proved, by adding a small quantity of yeast or other ferment to the sterile liquid, when fermentation sets in and proceeds vigor- ously. The chemical changes that are produced depend on the nature of 150 THE TECHNOLOGY OF BREAD-MAKING. the ferment that has been added. Yeast effects the decomposition of sugar into alcohol and carbon dioxide, other ferments cause putrefaction, and result in the typical bodies characteristic of that change. While these actions are progressing, the ferment is found to be developing and multi- plying. Further, if the ferment used be pure, one species only of organism is found in the liquid. Within any possible limits of observation no trans- formation of one ferment into another occurs : each belongs to a distinct and separate race of organisms. This statement does not deny the possi- bility of the modification of species by means of a natural process of evo- lution. There is, on the contrary, strong evidence in favour of the gradual evolution of species in course of time. 293. Varieties of Fermentation. — ^Among the many changes included under this term, the following are of importance in the consideration of our present subject : — Alcoholic fermentation, resulting in the production of alcohol and carbon dioxide ; lactic fermentation, in which sugar is converted into lactic acid ; acetous fermentation, in which alcohol is trans- formed into acetic acid ; viscous or ropy fermentation, resulting in the production of mannite and different viscous bodies ; and putrefactive fermentation, in which butyric acid and a variety of offensive products are formed. Alcoholic Fermentation and Yeast. 294. The nature of alcoholic fermentation has already been described. For the sake of exactness, Pasteur's definition of it is appended. “ Al- coholic fermentation is that which sugar undergoes under the infiuence of the ferment which bears the name of yeast or barm." When the word “ fermentation " is employed without any qualifying adjective, alcoholic fermentation is always understood. 295. Substances susceptible of Alcoholic Fermentation. — Pre-eminent among these are the glucoses, which are directly split up into alcohol and carbon dioxide. Most other sugars may also be fermented ; but usually, as in the case of cane-sugar, require first to be hydrolysed to glucose. As already explained, this change is effected, when yeast is added direct to cane-sugar, by the enzyme, invertase ; which latter functions indepen- dently of the cell itself, and therefore the inversion of the sugar is separate and distinct from fermentation proper. Both diastase and invertase are without action upon maltose ; but maltose undergoes inversion into glucose before fermentation by the action of maltase. Pure yeast is incapable of producing fermentation in either starch paste or dextrin ; neither can albuminous bodies, whether of vegetable or animal origin, be fermented. 296. Fermentation viewed as a Chemical Change. — ^The conversion of glucose into alcohol and carbon dioxide may be represented very simply by the equation — CeHi^Oe = 2C2H5HO -f 2CO2. Glucose. Alcohol. Carbon Dioxide. Taking the action on the glucose as the more simple of the two, the equation given above does not, however, represent the whole of the change, for 100 parts of glucose then would yield — Alcohol .. .. .. .. .. .. •. ..51*11 Carbon Dioxide . . . . . . . . . • • . 48*89 100*00 FERMENTATION. 151 Pasteur carefully collected the whole of the alcohol and carbon dioxide produced by fermentation of a definite weight of glucose, and found that he only obtained — Alcohol . . . . . . . . . . .. 48*51 per cent. Carbon Dioxide . . . . . . . . .. 46*40 ,, 100 — 94*91 = 5*09 parts of glucose not transformed into alcohol and carbon dioxide. The following bodies occur as subsidiary products — glycerin, succinic acid ; propyl, butyl, and amyl alcohols ; acetic, lactic, and butyric acids. Of these, the amount of glycerin and succinic acid produced have been found to be — Glycerin . . . . . . . . . . . . 3*00 per cent. Succinic Acid .. .. .. .. .. 1*13 ,, 4*13 This, therefore, leaves but 0*96 per cent, for the various higher alcohols, and the acetic, lactic, and butyric acids ; and also for that portion of the sugar that goes to help to build up fresh yeast cells. Buchner and Meissenheimer point out that acetic and lactic acids are invariably produced in alcoholic fermentation, and under conditions which negative the possibility of the action of bacteria or oxidation by the air. They regard the lactic acid as an intermediate product between the glucose and the alcohol, and suggest the following equation as representing the change which occurs : — CHO I CHOH I CHOH I CHOH I CHOH I CHOH Glucose. OH OH COOH COOH I CHOH 1 CH.OH H ^ j CH2H -> 1 CH3 OH I COOH I COOH OH I CH.OH 1 I CH.OH 1 H H 1 CH3 1 CH3 Water, 4 mols. Hypothetic Intermediate Product + Lactic Acid, 2 mols. ! H2O. CH2OH ^ + CO2 CH3 H"^ CH2OH + CO2 CH3 Water, Alcohol, Carbon 2 mols. 2 mols. Dioxide, 2 mols. Monoyer proposes the following equation as showing the production of glycerin and succinic acid from glucose — 4C6H12O6 + 3H2O = H2C4H4O4 + bCsHsCHOa + 2CO2 + 0. Glucose. Water. Succinic Acid. Glycerin. Carbon Oxygen. Dioxide. No free oxygen is however, detected in fermentation ; any that may be produced during the decomposition is probably used up by the yeast ceUs for purposes of respiration. Pasteur claims that the glycerin and succinic acid, as well as the alcohol and carbon dioxide, are normal products of alcoholic fermentation ; and further, that these bodies are produced from the sugar, and not from the ferment. He also shows that a portion of the sugar goes to help to build up the yeast globules. The quantities of glycerin and succinic acid pro- 152 THE TECHNOLOGY OF BREAD-MAKING. duced are not constant, but vary with the conditions under which fer- mentation proceeds ; when the action is slow the proportion of glycerin and succinic acid to alcohol is higher than with brisk and active fermentation. Brefeld, however, argues that glycerin and succinic acid are not products of alcoholic fermentation proper, but rather are pathological products arising out of the death of the yeast cells. The same view is advanced in a more modernly expressed opinion that these bodies are due to the destructive metabolism ^ of the cells. A small proportion of the carbohydrate, amounting to about 1 per cent., is assimilated by the yeast and employed in its constructive meta- bolism, being transformed into cellulose and fats. Jorgensen states that during fermentation by the pressed juice of yeast, i.e. by the separated zymase, glycerin is produced to the extent of from 3 to 8 per cent, of the fermented sugar, and is derived from the sugar. On the other hand, no succinic acid is formed. Acetic acid is produced in minute quantities, but somewhat more than in the fermentation with the living cell. This is probably due to the action of a special enzyme. {Micro- organisms and Fermentation, Fourth Edition.) 297. Chemical Composition of Yeast. — ^When yeast has been washed carefully so as to free it as far as possible from foreign matters, and then dried, it is found to have, according to Schlossberger, the following com- position — Surface Sedimentary Yeast. Yeast. Carbon . . Hydrogen Nitrogen Oxygen . . Ash (mineral matter) . . 48-7 46-4 6-4 6-2 .. 11-8 9-5 . . 30-7 34-5 . . 2-4 3-4 1000 1000 In~addition to* the above a number of other analyses might be quoted, showing that yeast is a body of somewhat variable composition ; mean- while attention is directed to the fact that yeast collected from the bottom of the fermenting liquid contains less nitrogen and carbon than does surface yeast. Various attempts have been made to separate yeast into its proximate principles, and estimate these : as a result it may be stated that yeast contains one or more bodies of the protein type. There are in addition, also present, cellulose and fatty matters. Payen gives the following as the result of an analysis of moisture-free yeast : — Nitrogenous Matter . . . . . . . . • • 62-73 Cellulose (envelopes) . . . . • . - • - • 22-37 Fatty Matters . . . . . . • • • • • • -*10 Mineral ,, . . . . . . • • • • • • 5-80 Naegeli states that the proximate constituents of a sample of yeast examined by him were as follows. The yeast was a sedimentary one, containing 8 per cent, of nitrogen : — Cellulose, Gum, and Cell Membrane . . . . 37 per cent. Proteins . . . . . . . • • • . . 45 ,, Peptones . . . . . . • • • • • • 2 ,, Fat . . . . • • • • • • • • • • 5 5 5 Extractives (Leucine, Cholesterin, Dextrin, Glycerin, Succinic Acid) . . . . . . 4 ,, ^ For an explanation of metabolism refer to Chapter XIII., par 415. FERMENTATION. 153 A sample of distiller’s compressed yeast examined by one of the authors gave the following results on analysis : — Proteins Fat Mineral Matter Water Cellulose, etc. (by difference) . . 12-67 0-80 2-05 . . 73-80 . . 10-68 100-00 The mineral matter of yeast is of great importance, and has been made the subject of careful analysis by Mitscherlich and others. The following table gives the composition of the ash of surface and sedimentary yeasts by Mitscherlich, and of the surface yeast of pale ale by Bull — Surface Y. Sedimentary Y. Phosphoric Acid, P 2 O 5 Mitscherlich. . . 53-9 59-4 Pale Ale, 54-7 Potash, K 2 O . . . . 39-8 28-3 35-2 Soda, Na 20 . . — — 0-5 Magnesia, MgO 6-0 8-1 4-1 Lime, CaO 1-0 4-3 4-5 Silica, Si 02 . . traces — — Iron Oxide, FesOs . . ■ — ■ — 0-6 Sulphuric Acid, SO 3 — — — Hydrochloric Acid, HCl — — 0-1 Yeast ash is therefore composed principally of phosphoric acid and potash : attention is directed to the similarity in composition between the ash of yeast and that of wheat. The above acids and bases probably exist in combination as the following salts : — Potassium Phosphates Surf. Y. . . 81-6 Sed. Y. 67-8 Magnesium Phosphate, Mg 3 (P 04)2 • . . . 16-8 22-6 Calcium Phosphate, Ca 3 (P 04)2 .. 2-3 9-7 The potassium phosphate must be looked on as a mixture of the dihydric phosphate, KH 2 PO 4 , and the monohydric phosphate, K 2 HPO 4 . The former of these phosphates contain 94 by weight of K 2 O to 142 of P 2 O 5 ; the latter contains 188 of K 2 O to 142 of P 2 O 5 . The weight of K 2 O in the surface yeast ash is between that required to produce either of these two potassium phosphates. The composition of the potassium phosphate of the sedimentary yeast ash nearly agrees with the formula, KH 2 PO 4 . 298. Yeast as an Organism. — Viewed as an organism, yeast may be said to be a plant of an exceedingly elementary structure ; it is in fact one of the simplest plants known. In very minute forms of life it is diffi- cult to distinguish animals and vegetables from each other, for with almost any definition that may be selected, one or two species wander over the border line. One of the most marked differences between the higher plants and animals is, that the former are able to derive their sustenance from inorganic compounds, their carbon from carbon dioxide, and their nitrogen from ammonia. Animals, on the contrary, can make no use of carbon or nitrogen for the purpose of building up their tissues, unless these bodies are presented to them in the form of organic compounds. Hence, in the economy of nature, it will be found that while plants live and develop, as before stated, by the assimilation of the elements of carbon dioxide and ammonia, animals subsist either on vegetable substances, or on the bodies 154 THE TECHNOLOGY OF BREAD-MAKING. of other animals. Yeast is unable to assimilate carbon from inorganic sources, but being able to derive its nitrogenous nutriment from inorganic bodies, is placed in the vegetable kingdom. The chemical changes pro- duced during the growth of the higher plants result in the building up of complex compounds from very simple ones : in the animal, complex bodies are required as nourishment, and are broken down into simpler bodies. The complexity here referred to is that which may be measured by the number of atoms in the molecule of the body ; thus, water is a very simple compound, while starch has a most complex molecular structure. The chemical operations of plant-life may be summed up as consisting of syn- thesis ; those of animal existence as analysis. In order to effect the syn- thesis of plant compounds from the substances at the disposal of vegetables, force is required ; this they usually obtain in the form of heat from the sun. The act of growth of a plant means, therefore, a continual absorption of heat. On the other hand, animals, in taking complex bodies and breaking them down into simpler ones, liberate heat ; consequently, one result of animal life is that heat is continuously being evolved. Yeast, in this particular, partakes both of the nature of an animal as well as a plant. Its nitrogen may be obtained from inorganic sources, but is more usually derived from suitable protein matter, such as peptones. On the other hand, the carbon of yeast is taken from sugar with the breaking down of that body into simpler compounds, and the consequent liberation of heat ; therefore during fermentation the temperature of the liquid rises considerably. From a chemical standpoint, yeast combines in itself the vegetable functions of synthesis with the animal functions of analysis. 299. Botanic Position of Yeast. — This organism belongs to the family of Fungi. Fungi . — The fungi are those plants which are destitute of chlorophyll (the ordinary green colouring matter of grass, etc.). They reproduce by buds and spores. Spores. — Spores are a variety of cell, and in all fungi the spores are similar in essential points to the yeast cell ; notwithstanding that they may vary considerably in appearance and details of structure. Hyphce. — The spore, on being sown in a suitable medium for its growth, throws out a long delicate stem of tubular structure, termed a “ hypha.'^ A group of these hyphse constitute the fungus. Mycelium. — One of the best typical examples of a fungus is the common green mould found on old boots, bread, jam, etc. This has received the name Penicillium glaucum. On examining a specimen of such mould from the top of a pot of jam for instance, its base is found to consist of an interlaced growth of hyphse, forming a more or less compact web or skin on the jam. This layer of intermingled hyphse is termed the “ my- celium.’’ From its upper surface a number of hyphse project into the air, each bearing a quantity of very fine green powder, these are termed “ aerial hyphse.” On the lower surface again, other hyphse grow down root-like into the liquid, which supports the mould ; these are the “ submerged hyphse.” Conidia. — Some of the aerial hyphse terminate in short branches, each of which is divided into a series of rounded spores which are only loosely attached to the hyphse, and so may easily be shaken off ; these spores are termed “ conidia.” Each separate conidium, if sown in a suitable Liquid, develops a young fungus, which in its turn rapidly multiplies. Sporangia. — Some of the fungi, as for instance that known as Mucor mucedo, have their hyphae terminated in rounded heads ; each of these is called a “ sporangium.” FERMENTATION. 155 300. Varieties of Yeast. — The yeast fungi constitute the genus Saccha- romyces ; they are so named because they mostly live in saccharine solu- tions, converting the sugar present into alcohol. The saccliaromyces have no mycelium, and in common with the other fungi reproduce by buds and spores. The genus saccliaromyces comprises several species, a detailed description of^which will subsequently be given.!! 301. Nature of Yeast Cells. — ^The yeast organism consists of cells, mostly round, or slightly oval, from 8 to 9 /x in diameter ; the cells may occur either singly or grouped together as colonies. It is impossible to obtain any real knowledge of the physical structure of yeast without a careful and systematic personal examination by the microscope : it has been thought well, therefore, to arrange the following description in such a form as to constitute a guide to actual yeast examination. 1. Take either a little brewers’ yeast, or bakers’ compressed distillers’ yeast, and mix with some water until a milky fluid is produced. By means of a pointed glass rod, take a small drop of this fluid and place it on a clean microscopic slide, and gently cover with a cover-glass. Arrange the micro- scope in a vertical position, and proceed to examine the yeast by means of a fairly high power (| objective). Notice that the yeast consists of cells, of which measure a few by means of the eye-piece micrometer, and observe that their dimensions agree with those just given. Each cell consists of a distinct wall or envelope, containing, within, a mass of more or less gelatinous matter devoid of organic structure. The interior substance is named “ protoplasm ” ; this term being applied to that ultimate form of organic matter of which the cells of animals and plants are composed. The protoplasm of the yeast cell is not homo- geneous, but is always more or less dis- tinctly granular. Run in magenta solution under the cover-glass. (This is readily done by placing a drop of the solution in contact with one side of the cover-glass, and placing a strip of blotting-paper on the other.) Notice that the sac or envelope remains uncoloured, while the protoplasm stains comparatively deeply ; the vacuoles are unstained. One or more circular spots can usually be seen in yeast cells as obtained from a brewery ; these are caused by the gelatinous matter moving toward the sides of the cell, and leaving a comparatively empty space, containing only watery cell-sap ; hence these spots are termed vacuoles. A specimen of yeast is shown in Figure 9. 2. Remove the slide from the microscope, and burst a few of the cells by placing some folds of blotting-paper on the cover-glass, and then pressing sharply with the end of a pencil or rounded glass rod. Again examine under the microscope, note the empty sacs and the extruded protoplasm, which does not readily mix with the water. If practicable, try this experiment with yeast of various ages ; very old yeast cells break more easily, and the protoplasm is more fluid, and takes the colour more readily. By using the magenta stain in a dilute form, old and dead cells may be differentiated from those which are healthy and vigorous — the latter remain unstained, or take up the stain very slightly, while dead cells readily and quickly acquire a magenta hue. 3. Take six clean cover-glasses and coat one side of each with a thin Fig. 9. — Saccharomyces Cerevisice. a, a bud colony ; b, two spore-forming cells (after Liirssen). 156 THE TECHNOLOGY OF BREAD-MAKING. Iyer of yeast, by painting on the mixture of yeast and water by means of a earners hair brush, and set aside until thoroughly dry. The yeast adheres firmly to the glass, showing that the outside of the cell-walls is mucilaginous in character. 4. Add a drop of solution of iodine in potassium iodide to one of these cyers, let it stand five minutes, and then wash slightly in water, and mount the cover-glass, yeast side downward, on a glass slide. The cell-wall stains slightly, and the protoplasm becomes dark brown; but no blue colour IS produced ; starch therefore is absent. As the cell envelope is continuous, containing no apertures, the iodine solution must have passed through its substance. ^ 5. Similarly treat another cover preparation with iodine, and then, without washing, add one or two drops of 70 per cent, sulphuric acid. The cell-contents acquire a deeper brown stain, and the cell walls become brown- ish yellow, but do not show any blue colouration. The cellulose of the walls of the cells of most higher plants acquire a blue colour with this treatment, showing the presence of a cellulose allied to that of starch, but the cellulose of yeast, and of fungi generally, is devoid of this property. 6 Treat the yeast on another cover-glass with solution of potash. Tlie protoplasm is dissolved, leaving nothing to be seen but empty cell-walls. 7. Treat another cover-glass preparation with a solution of osmic acid. Note that small, sharply defined, dark coloured bodies are seen. Jorgensen regards these as cell-nuclei of the same nature as those generally observed in the majority of plants without this treatment. 8. Break down a little yeast with water, and focus under the micro- scope, so as to observe distinctly the small bright granules of fat within the protoplasm of the cells. Put a piece of blotting-paper on one side of the cover-glass, and run in at the other a few drops of ether from a fine pipette — the fat granules dissolve and disappear. ^ 302. Life History. — On examining under a microscope a sample of skimmed yeast, as obtained from the brewer, it is found to consist either of single cells, or cells joined together in pairs. Such yeast having usually remained quiescent for some time, the cells rarely occur in large groups because, with standing, they tend to separate from each other. The granu- lations in the protoplasm, and also the vacuoles, should be visible. On placing a very small quantity of this yeast in a suitable liquid for its groAvth, as malt wort, at a temperature of about 30° C. (86° F.), the cells, which at first were somewhat shrunken and filled throughout with granular matter, increase in size from absorption of the liquid in which they are placed. At the same time the granulations becomes less distinct, and the whole cell assumes a more transparent and distended appearance. To observe this effect, mount a few cells on a microscopic slide with warm malt wort, and keep under observation with the microscope. After a time the round yeast cells become slightly elongated through the for- mation of a small protuberance at one end ; this grows more marked, until shortly a neck is formed by a contraction of the cell wall. But still,' careful examination shows that there is a distinct opening through this neck, the contents of the smaller portion being continuous with those of the cell. As the growth continues, the strangulation at the neck pro- ceeds until the cell wall completely shuts off the protuberance, which then constitutes a new or daughter cell, attached to the parent. This operation is known as “ budding.” The one parent cell is capable of giving off several buds in succession ; but after a time its reproductive energy is exhausted, and the cell breaks up. These daughter cells in their turn give rise to FERMEXTATIOX. 157 other cells, and so the multiplication of yeast globules proceeds with remark- able rapidity. Pasteur states that on one occasion he Avatched two cells for two hours ; during that time they had multiplied by budding into eight, including the original pair of cells. At this stage, buds of every size may be seen attached to the parent cells ; some are so small as to be scarcely visible, while others are nearly as large as the parents. With the progress of this grov'th and development, sugar is being decom- posed, the liquid becomes alcoholic, and its specific gravity diminishes. The brewer terms this change “ attenuation,” or a becoming thinner. Another reason for the use of this name is that the liquid becomes less viscous, from the conversion of the sirupy solution of mal- tose into the highly mobile liquid, alcohol. Simultaneously with the production of alcohol, carbon dioxide gas is evolved ; this rapidly rises to the sur- face, and carries up with it the yeast cells, which float on the top of the fermenting wort. Yeast now skimmed off is found to consist of colonies of some scores of cells linked together ; the majority of these are clear and almost transparent. Usu- ally in the middle of each such group, the old or parent cell can be recognised by its darker contour and comparatively ex- hausted appearance. As the quantity of sugar in the liquid becomes less, the fermentation slackens, and finally ceases. If the cells then be again exam- ined, under the microscope, they will be found to have a firmer outline, and tlieir contents will be more granular. In what may be termed old age of the yeast cell, the walls become abnormally thick, and the granulations very dense. The yeast, on being removed from the fermenting tun, is usually set aside in store vats ; on standing, it gradually assumes the appearance described as that of the yeast used for “ pitching ” or starting tlie fermentation. The quantity of yeast thus obtained is considerably in excess of that first added to the malt wort. In the moist state, yeast decomposes quickly ; hence if the store be kept for any length of time, the cells rapidly alter in character. The walls become soft, thin, and weak, and the interior protoplasm changes from its normal granular gelatinous condition to a watery consistency. After a time, if viewed Avith a high poAAer, a distinct “ BroAvnian ” moA^ement is seen of particles suspended in the contents of the cell. The particles may A^ery possibly consist of minute fragments of cellulose from the enve- lojies. After a time the AAalls also break doAAn and all traces of the yeast organism disappear. The normal bodies produced by the decomposition of nitrogenous and protein bodies may noAv be detected in the liquid : putrefaction rapidly folloAAS, AA'ith the production of a most offensive odour. Such is in broad outlines the life history of a yeast cell, AA'hen soAA'n under normal conditions in malt AAort. Fig. 10. — Saccharomyces Cerevisice. a. High Yeast, at rest ; b, High Yeast, actively budding c, Low Yeast, at rest ; d, Low Yeast, actively budding. 158 THE TECHNOLOGY OF BREAD-MAKING. Distillers’ yeast putrefies much more readily than does that of the beer brewer : the hops used in the latter act as an antiseptic, and the yeast putrefies much less rapidly. Evidence of this is afforded in the method employed for the preparation of invertase from brewers’ yeast. High yeast produces a beer having a special and characteristic flavour, which distinguishes it at once from beer brewed with low yeast. 303. Influence of Temperature on Yeast Growth.— The temperature most favourable to the growth of yeast is from 25° C. to 35° C. (77° and 95 F.) Between these points yeast flourishes and grows well ; at tem- peratures lower than 25° growth proceeds, but not so rapidly. At a tem- perature of about 9° C. (49*6° F.), the action of yeast is arrested ; the vitality, however, of the ceU is only suspended, not destroyed, for with a higher temperature it again acquires the power of inducing fermenta- tion. Actual freezing does not destroy yeast, provided the cells do not get mechanically ruptured or injured. Above 35° C., the effect of heat is to weaken the action of yeast, until at a temperature of about 60° C. (140° F.), being that at which protein principles begin to coagulate, the yeast is destroyed. This applies to moist yeast. When dry, the cells are able to stand higher temperatures than when suffused with water ; thus, dried yeast has been heated to 100° C. without destroying its vitality. Although a temperature of from 25° to 35° C. conduces to the rapid growth of yeast, yet there are other circumstances which render it ad- visable to conduct actual brewing operations at a much lower temperature. In English breweries, a pitching temperature of about from 18° to 19° C. (65° F.) is commonly employed : during the fermentation the heat rises to from 21° to 22° C. (72° F.). Faulkner states that a tun of pale ale, containing 200 barrels of 36 gallons, on being pitched with 600 lbs. of yeast at 14-5° C. (58*1° F.) had sufficiently attenuated in 46 hours, during which time the temperature had risen to 22-2° C. (72° F.). 304. Substances Requisite for the Nutriment of Yeast.— It has several times been stated that sugar is required by yeast during its growth : as yeast cells likewise contain nitrogenous matter, and also certain inorganic constituents, it is evident that nitrogen in some form, and also the requisite mineral salts, must be supplied to the growing yeast. Summing these uji, yeast requires for its growth, sugar, nitrogenous compounds, and appro- priate inorganic matter. 305. Saccharine Matters. — These occupy the first and paramount position, as^being absolutely necessary for the production of alcoholic fermenta- tion. Pure yeast sown in a pure sugar solution causes it to ferment ; but without the sugar neither alcohol is produced, nor carbon dioxide evolved. Malt wort, grape juice or “ must,” and dough, all ferment on the addition of yeast, because they all contain sugar. “ It is necessary indeed that sugar be present ; for if we abstracted by some means or other from the must or dough all the sugar contained in it, '[and also all substances capable, by the addition of yeast to flour, of being converted into sugar], without touching the other constituents, the addition of yeast would produce no gas. Everything would remain quiet until the moment when signs of a more or less advanced putrefaction showed themselves.” (Pasteur). It should be mentioned that yeast is also capable of inducing definite chernical changes in a few other bodies : among these is malic acid, which is broken up into succinic and acetic acids, carbon dioxide, and_water. It is also stated that yeast decomposes glycerin into propionic Tho clause in brackets, [ ], is inserted by the authors. FERMENTATION. 159 and acetic acids ; this change has been denied by Roos and Brown. As neither malic acid nor glycerin (in the free state) occur as constituents of flour, their fermentation lies altogether outside the scope of the present work. The glucoses, or sugars of the C6H12O6 group, are the only sugars capable of direct fermentation ; of these, glucose or dextrose is more readily decom- posed by yeast than is fructose. The two being together in the same solu- tion, the fructose remains unacted on until the disappearance of the whole of the glucose. Certain other sugars are capable of indirect fermentation by yeast ; among these are cane-sugar, which first, however, requires to be hydrolysed to glucose by the action of the invertase or soluble diastatic body secreted by the yeast cell. As already explained, this preliminary diastasis can be effected by yeast water, that is, water with which yeast has been shaken up, and then filtered in order to remove the whole of the yeast cells ; such yeast water is, of itself, incapable of setting up alcoholic fermentation. Yeast causes certain effects, of which it is difficult to say whether they are absolutely correlatives of vital acts, as an organism, or merely results of diastasis. For practical purposes, it matters little to which of these two classes of chemical action any specifice change produced by yeast belongs ; in such cases it is the action of yeast, as a whole, that is of importance. Sugar of milk is incapable of fermentation by yeast. Yeast alone is also unable to ferment either starch paste or dextrin : these bodies require some more powerful agent for their diastasis, such as malt extract. As mentioned in Chapter VIII., yeast, indirectly through its action on the proteins of barley or wheaten flour, transforms starch paste into dextrin and maltose, after which the yeast induces fermentation. Consequently, the two, yeast and proteins, in conjunction, are capable of effecting changes which neither can separately produce. It almost goes without saying that water is necessary for the develop- ment of yeast, so requisite is it that saccharine solutions containing over 35 per cent, of sugar are incapable of fermentation. Such a solution, by out- ward osmose through the cell wall, deprives the yeast of its normal proportion of water as a constituent. 306. Nitrogenous Nutriment. — ^Yeast is capable of utilising, during its growth, the nitrogen of ammoniacal salts (but not that of the acid radical of nitrates) ; thus, a solution of pure sugar, mixed with either ammonium tar- trate or nitrate, and certain non-nitrogenous inorganic salts, permits a healthy development of yeast. With the multiplication of the yeast cells, the amount of protein matters present increases ; therefore, by the action of yeast, the ammonium compounds are transformed into protein bodies. Al- though yeast thus acts on ammonium salts, organic nitrogenous compounds form a more suitable nutriment ; among such substances, the soluble pro- teins of yeast itself are especially seized on by yeast. Consequently, always supposing the presence of the inorganic salts required by yeast, yeast water and sugar form an admirable medium for its growth and development ; so, too, do natural saccharine juices, as “ must,'' the juice of apples, pears, etc. In addition to these, malt infusion must be mentioned. Albumin, whether from the white of egg or vegetable albumin, is entirely unfit for the nourishment of yeast. This fact is stated with force by Pasteur, whose opinion is confirmed by that of Mayer, who ascribes the inactivity of albumin, casein, and other similar bodies, to their highly colloid nature. The solution molecules of soluble proteins of malt have such an appreciable volume, that filtration of the solution through a thin porous earthenware diaphragm under slight pressure is sufficient to prevent these bodies from passing through into the filtrate (Brown and Heron). It may then be readily 160 THE TECHNOLOGY OF BREAD-MAKING. understood that yeast cell walls are impermeable to protein bodies. The- compounds produced by digestion of albumin and its congeners, the peptones, are much more diffusible, and are eminently suited for affording the requisite nitrogenous nutriment to yeast. Pepsin itself forms an admirable yeast food. Schiitzenberger considers it probable that must, malt wort, and yeast M ater owe their power of nourishing the cells of yeast, not to the protein bodies, but to certain of their constituents that are analogous to the peptones, and M'hich have the property by osmose of passing through the cell v’alls. 307. Mineral Matters necessary for the Growth of Yeast. — ^For his experi- ments on yeast, Pasteur used yeast ash as the source of his mineral matter. It is obvious that this substance may be replaced by an artificial mixture of the salts contained therein. A reference to Mitscherlich's analyses of yeast ash shows that the principal ingredient is potassium phosphate ; together with this, there is magnesium phosphate and small quantities of phosphate of calcium. Pasteur finds, v hen an unw eighable quantity of yeast is sown in a solution of pure sugar and ammonium tartrate, that development of cells and fermentation do not take place ; the addition of yeast ash enables both to occur. Mayer endeavoured further to ascertain what salts are, in par- ticular, necessary among those present in the ash. Potassium phosphate is absolutely indispensable ; neither sodium nor calcium phosphates are com- petent to replace it. Magnesia is also of great value, if not indispensable, to the development of yeast ; this base may be supplied either as sulphate or phosphate. Lime seems not to be absolutely necessary to yeast growth. 308. Insufficiency of either Sugar or Nitrogenous Matter only for the Nutriment of Yeast. — ^Yeast is incapable of healthy development in solutions of sugar alone. A limited growth occurs when the quantity of yeast added is considerable, because, by a species of cannibalism, the healthier and stronger cells survive and develop to some extent by feeding on the nitro- genous and mineral matters obtained from the others. Necessarily, such grovTli must soon stop. Yeast was stated by Pasteur to multiply in a nitro- genous liquid, such as yeast water, “ even when there was not a trace of sugar present, provided always that atmospheric oxygen is present in large quan- tities.’' Yeast finds air to be under these conditions an absolute necessity. Without it no development proceeds, nor is there any but the slightest trace of alcohol found ; carbon dioxide gas is evolved, being formed by direct carbonisation of oxygen derived from the air. But, for this change, it must be remembered that air is a necessity. Assuming the correctness of Pas- teur’s viev'S as to the growth of yeast by the assimilation of atmospheric oxygen, and expiration of carbon dioxide, it is necessary to remember that the conversion of oxygen into carbon dioxide gas results in no change of volume ; this is clearly seen by reference to the molecular equation — C + O2 = CO2. Carbon. Oxygen. Carbon Dioxide. Under ordinary conditions of fermentation, albumin does not evolve alcohol or carbon dioxide gas. Neither does pepsin when similarly treated, although tills body is v eil adapted as a nitrogenous food for yeast. Albumin is also unacted on when its solution is first of all mixed 'with a 2J per cent, solution of sodium chloride. 309. Behaviour of Free Oxygen on Yeast. — ^As stated in the preceding ])aragraph, Pasteur regarded atmospheric oxygen as capable of acting as a substitute for sugar in the nutriment of yeast, and accordingly he examined very carefully the general behaviour of free oxygen and yeast to each otlier. In consequence, he developed the follo'wing theory of fermentation, which for some time was generally accepted. FERMENTATION. 161 Pasteur states, as a result of experiment, that yeast grows better in shallow than in deep vessels. As a result of some determinations made, in which one sample of yeast and a saccharme solution were kept in an air-free flask, and another in a shallow vessel, by which it was freely exposed to the atmosphere, he finds that the proportion of yeast produced to the sugar con- sumed was much greater in the latter than in the former instance. By dint of most careful experiment he further finds, while a fermentable liquid may be made to ferment out of contact with air, yet in order that it shall do so it is essential that young and vigorous yeast cells shall be employed. Witli older yeast the fermentation proceeds more slowly, and with the production of mal-shaped cells, while a yeast still older is absolutely incapable of repro- duction in a liquid containing no free oxygen. This is not due to the yeast being dead, for on aerating the liquid, either with atmospheric air or oxygen, fermentation proceeds apace. Pasteur therefore concluded that under favourable circumstances yeast functions as a fungus ; that is, it lives by direct absorption of oxygen from the air, and the return of carbon dioxide gas. He consequently assumed the following relationship between its life in free oxygen and its life when submerged in a sugar solution — Let some yeast be sown in a sample of malt wort, containing as much oxygen as it can possi- bly dissolve ; the yeast starts active growth, and rapidly removes all the free oxygen from the liquid, after which it commences to attack the sugar. Dur- ing this time, yeast will be living not as a ferment but as a fungus, namely, by direct absorption of oxygen. Could each yeast cell be supplied with all the oxygen it requires in the free form, it is probable that it would not exert the slightest fermentative action ; it would, at the same time, grow and reproduce active healthy cells with great rapidity. As soon as the whole of the air is exhausted, the yeast attacks the sugar, and obtains its oxygen by the decom- position of that compound, and ordinary fermentation proceeds. Conse- quently, yeast must be viewed as being capable of two distinct modes of existence, in free oxygen as a fungus ; when submerged in a saccharine solu- tion, as a ferment. Of the two the fungus life is the easiest ; that is, yeast can perform its vital functions more readily when it obtains its oxygen in the free state than when it has for that purpose to effect the decomposition of large quantities of sugar. If yeast be grown continuously in saccharine solutions, under conditions which result in the rigid exclusion of air, fermen- tation becomes more and more sluggish : the conditions of life are in faet more severe than the yeast can stand, the struggle for existence is too acute, and its vitality succumbs. But if a sample of fermenting wort be taken at a time when, although the sugar is far from exhausted, the fermentation has become sluggish, and then thoroughly aerated by some means which shall bring it into full contact with air, a remarkable change ensues. At first the fermentation slackens, but the rate of growth of yeast increases ; this is due to its living as a fungus on the dissolved free oxygen. During this time it exerts little action as a ferment, but grows and accumulates vital energy. After a while, the fermentation proceeds much more vigorously than before the aeration ; this is a necessary result of the renewed energy and vitality of the yeast cells. That oxygen is capable of acting in some way as a stimulant to fermenta- tion was known to brewers long before the announcement of this theory by Pasteur, as they had found that by “ rousing (stirring) tuns of wort that Avere fermenting sluggishly, the fermentation was invigorated. The agita- tion following from this rousing aerated the wort. To borrow his own words, Pasteur summed up his theory of fermentation in the following terms : — “ Fermentation by yeast is the direct consequence of the processes of nutrition, assimilation, and life, when these are carriep on without the agency of free oxygen. . . . Fermentation by means of yeast M 162 THE TECHNOLOGY OF BREAD-MAKING. appears, therefore, to be essentially connected with the property possessed by this minute cellular plant of performing its respiratory functions, some- how or other, with oxygen existing combined in sugar. Its fermentative power varies considerably between two limits, fixed by the greatest and least possible access to free oxygen which the plant has in the process of nutrition. If we supply it with a sufficient quantity of free oxygen for the necessities of life, nutrition, and respiratory combustions, in other words, if we cause it to live after the manner of a mould, properly so called, it ceases to be a ferment ; that is, the ratio between the weight of the plant developed and that of the sugar decomposed, which forms its principal food, is similar in amount to that in the case of fungi. On the other hand, if we deprive the yeast of air entirely, or cause it to develop in a saccharine medium deprived of free oxygen, it will multiply just as if air were present, although with less activity, and under these circumstances its fermentative character will be most marked ; under these circumstances, moreover, we shall find the greatest disproportion, all other conditions being the same, between the weight of yeast formed and the weight of sugar decomposed. Lastly, if free oxygen occur in varying quantities, the ferment power of the yeast may pass through all the degrees comprehended between the two extreme limits of which we have spoken.” According to this view, fermentation is a starvation phenomenon, brought about by the want of free oxygen during the life of yeast cells in a fermentable liquid. 310. Brown on Influence of Oxygen on Fermentation. — In 1892, Adrian J. Brown contributed an important paper on this subject to the Journal of the Chemical Society, which paper necessitates a reconsideration of the theory of fermentation. In his experiments. Brown employed the method of count- ing the yeast cells in his various solutions, by means of the hsematimeter, instead of weighing the yeast, as had been done by Pasteur in his various researches. This method of working has the advantage that the results are capable of being referred to the amount of effect being produced by the action of an unit cell. Brownes first conclusions were that “ when any fermentable nutritive solution, such as malt wort, or a solution of dextrose in yeast water, is inocu- lated with a high fermentation yeast, and kept at a temperature favourable to yeast growth, the cells reproduce themselves rapidly for a time, and then their reproduction ceases, and that the fermentation of the solution may still be carried on by the continued life of the cells already formed.” Further, he found that with the same liquid, under the same conditions, the cells increase to about the same maximum, no matter how the number of cells introduced to start the fermentation may vary. In support of this view, the following experiment is quoted — Two flasks, A and B, were taken, and in each 150 c.c. of the same malt wort was placed, and then a different amount of the same yeast added to each. The contents of the flasks were throughly agi- tated, and the cells counted by the haematimeter. (The standard volume of the instrument employed was 4000 of a cubic millimetre, called hereafter “Standard Volume.”) The flasks A and B contained respectively 0*93 and 7*44 cells per standard volume. The flasks were kept at 25° C. until fermentation had completely ceased, when the cells were again counted. In flask A the number of cells per standard volume had increased from 0'93 to' 25*24 “ whereas in flask B the increase was from 7*44 to 27*08. The rate of increase differed widely, but the ultimate number of cells produced was approximately tlie same. From these and a number of other similar experi- ments, the conclusion is drawn that in such fermentations the number of 3 ^east cells increases to some fixed maximum, irrespective of the number originally added to induce fermentation. FERMENTATION. 163 The next point was to experiment by adding more cells than this maxi- mum number, two similar flasks of malt wort were respectively seeded with 6*0 and 70*8 cells of yeast per standard volume. Fermentation was allowed to proceed, and, at its close, in No. 1 flask the cells had increased from 6*0 to 24*9, while in No. 2 they had decreased from 70*8 to 68*2 cells. In this experiment 24*9 cells may be regarded as the maximum number that the wort used would grow, consequently with No. 2 flask there is no increase. Brown regards the actual diminution as due to the death and disintegration of some of the cells. In the second flask as well as the first, fermentation proceeded with great rapidity. Other experiments made yielded the same results ; therefore, if a nutritive liquid be seeded with a considerably larger number of yeast cells than the maximum number it is capable of producing by reproduction, fermentation proceeds, and a method is afforded of studying fermentation without multiplication of yeast cells. Having a constant quantity of yeast, throughout the experiment, evidently eliminates many disturbing factors present when the quantity of yeast is variable. Brown in the first place applied this method to the investigation of the action of oxygen on yeast. A malt wort of 1065 sp. gr. was taken, and yeast added to the extent of 85 cells per standard volume. 120 c.c. of this solution were poured into a flask. A, so as to nearly fill it ; its mouth was then stopped in such a manner as to permit the escape of carbon dioxide gas, but to prevent air gaining access to the solution. 120 c.c. of the same solution were also placed in another flask, B, of about 1500 c.c. capacity,so that it simply formed a thin layer on the bottom ; this flask was so arranged as to permit a current of air being drawn through the liquid. Both flasks were thus similar, ex- cept that from the one air was excluded, while the contents of the other were subjected to abundant aeration. The fermentation was conducted at 19°, and, after the end of three hours, arrested by the addition of salicylic acid. The liquids were distilled, and the amount of alcohol produced estimated from the specific gravity of the distillate. In A, flask, without aeration, 3*35 grams of alcohol had been formed ; while in B, through which a continu- ous current of air had been drawn, the alcohol amounted to 3*56 grams. The number of yeast cells remained unaltered at the close of the experiment, but slight attempts at abortive budding were observable, particularly in the aerated flask. Another experiment was tried, in which the fermentable medium was a solution of glucose in yeast-water, which was seeded with 90 cells per standard volume. At the end of three hours, fermentation was arrested, and the residual sugar in the solutions determined polarimetrically In A (unaerated) 1 *96 grams of glucose had been fermented ; while in B (aerated) the quantity of fermented glucose was 2*32 grams. In neither case was there any sign of budding or enlargement of the cells. In order to meet the objection that the mechanical effect of aeration might stimulate the action of the cells in the B flasks, the following pairs of experi- ments were made in which the A flasks were subjected to the action of currents of carbon dioxide and hydrogen respectively, and at about the same rates as the air through the B flasks. The following were the results : — “ A '' flask, with carbon dioxide passed, 3-99 grams of glucose fermented. Companion B flask, with air passed, 4*28 ,, ,, ,, “ A ” flask, with hydrogen passed, 2*26 ,, ,, ,, Companion B flask, with air passed, 2*45 ,, ,, ,, In every case the most work is done in the presence of oxygen. In all the preceding experiments, as the consequence of the employment of large quantities of yeast, fermentation proceeded very rapidly ; in order to watch the results under slower conditions, experiments were made with 164 THE TECHNOLOGY OF BREAD-MAKING. fermentation at a low temperature, 7° C. (44*6° F.), and were continued for 24 hours. Through A flask hydrogen had been passed, and 4*882 grams of glucose had been fermented ; while in B flask, through which air had been passed, the quantity was 5*289 grams. During the 24 hours 190 litres of air had been passed through B flask. In none of the preceding experiments was there any multiplication of yeast. These results are in striking contradiction to the views of Pasteur, who affirms that in the presence of excess of oxygen fermentation practically ceases. Brown, on the contrary, finds uniformly that in the presence of oxygen, fermentation is more vigorous than in its absence. As Pasteur’s results were obtained by weighing yeast, Brown in one ex- periment weighed as well as counted his yeast. At the commencement there were in each flask 87*6 cells per standard volume, and in 100 c.c. 1*903 grams of Altered, washed, and dried yeast. Fermentation resulted in the destruction of 6*20 grams of glucose in the hydrogen flask, and 7*38 grams in the air flask. No increase in the number of cells had occurred, but the weights of yeast, treated as before, were respectively from hydrogen flask 2*130 grams, and air flask 2*060 grams. In both cases there is a slight increase in weight, due probably to assimilation by each individual cell, but in both cases at the flnish of the fermentation we have almost exactly the same weight of yeast, as well as the same number of cells. Hence equal amounts of yeast, whether determined by weighing or counting, ferment rather more sugar when supplied with air than when deprived of it. Another important experiment proceeded on different lines. The object was to determine the rate of multiplication of cells, and, at the same time,, the rapidity of fermentation. Six similar flasks of glucose in yeast water were taken, and each seeded with 0*65 yeast cells per standard volume. All were allowed to ferment under similar conditions. At intervals, one of the flasks was taken and the number of yeast cells found, and the quantity o£ alcohol produced determined, with the following results : — 1 A. B. C. D. E. F. Total Grams of Proportion , i Mean grams of Alcohol of grams 1 Number number of Alcohol found in of Alcohol Interval Time of Commence- of Cells Cells ' found in each per 100 c.c. of time in ment of Experiment, found in present each interval of to a each and .subsequent eaeh during Experiment Time in Single Cell Experiment Ueterminations in Experi- each in 100 c.c. 100 c.c. of in each in Hours. Separate Flasks. ment. interval of the the interval of of Time. Liquid. Liquid. Time. 1 Jan. 9, 11 p.m. 0-65 _ I ,, 10, 11 a.m. 4-87 2-76 0-654 0-654 0-237 12 ,, 10,11p.m. 1203 8-45 1-933 1-279 0-151 1 12 ,, 11,11 a.m. 15-38 13-70 2-975 1-042 0-076 12 ,, 12, 1 1 a.m. 15-88 15-63 4-217 1-232 0-083 I 24 „ 13,11a.m. 15-80 15-83 6-187 1-950 0-123 ' 24 It will be noticed tliat tlie number of cells increases rapidly in the earlier stages of fermentation, and that also the proportion of alcohol produced by each single cell is greatest during the first twelve hours. This is contrary tO' general views that fermentation is slower during the more rapid multiplica- tion stage of the development of yeast, an effect which was supposed to be a result of oxygen in the liquid, which, while aiding the reproduction of the- FERMENTATION. 165 cells, at the same time limited their fermentative power. Brown’s experi- ments contradict this theory. In a further paper communicated to the Chemical Society in 1894, A. J. Brown devotes himself to a critical examination of Pasteur’s theory ; of Avhich criticism the following is a brief outline : — Pasteur, as previously ex- plained, compared the fermentative power of yeast cells under varying con- ditions of aeration, and arrived at the conclusion that when aeration is per- fect, fermentative power ceases, and when a oration is reduced, fermentative power increases. The type of experiment used for this purpose was that of determining, under varying conditions of aeration, the proportion of the weight of the yeast formed to the weight of sugar fermented. This ratio of yeast to sugar is, Pasteur considers, an expression of fermentative power. If, as Pasteur argued, the amount of yeast formed during fermentation were in direct proportion to the sugar fermented, the ratio of yeast to sugar would remain constant, however much or little sugar were available. Brown con- tends that his experiments show conclusively that such is not the case, there being no direct proportion between weight of yeast formed and sugar fer- mented. In order to show that the total fermentative power of yeast has not been measured in Pasteur’s experiments, a fermentation was carried on under aerobic conditions, until the sugar originally present was decomposed. Afterwards, using the principle of overcrowding as a means of preventing reproduction, the crowded cells were fed with more sugar. Feeding was carried on at intervals until three times the original weight of sugar had been thus fermented, but no increase in the weight of yeast had occurred. In Brown’s opinion, Pasteur’s apparent deficiency in fermentative power was due to the employment of a limited amount of sugar in the experiment. Brown objects to Pasteur’s aerobic experiments in shallow dishes, because they were allowed to continue but a limited time, and therefore a time factor is introduced : further, cane-sugar was used as the fermentable material, and consequently the results were complicated by the hydrolytic functions of the yeast having to precede fermentation. Pasteur’s measure of fermentative power in the experiments referred to is an expression of the action of the inversion and fermentative functions in a limited time. Brown concludes by submitting, in place of Pasteur’s theory that fermentation is “ life without air,” the hypothesis that “ yeast cells can use oxygen in the manner of ordinary aerobic fungi, and probably require it for the full completion of their life- history ; but the exhibition of their fermentative functions is independent of their environment with regard to free oxygen. Nothing in the results of any of Pasteur’s experiments are contradictory to such an hypothesis. 311. Buchner’s Views on the Action of Oxygen. — ^Mention has already been made of Buchner’s researches on zymase as the agent through which yeast effects alcoholic fermentation. That investigator, together with Rapp, pointed out in 1898 that Pasteur’s views of fermentation were biologically ■correct, inasmuch as yeast has acquired the power of acquiring its oxygen by means of fermentation instead of by the more usual course of the direct assimilation of oxygen. They show further that oxygen stimulates the multiplication of yeast cells. So thoroughly, however, has yeast acquired the fermentation habit, that even in the presence of oxygen, yeast is far more active as a fermentative agent, than as a mere respiratory organism. 312. Mal-Nutrition of Yeast. — ^When yeast is deprived of a normal proportion of each of the necessary constituents for its healthy life, the vital- ity of the cells is thereby lessened. One result of this is that the cells tend to assume abnormal forms. Thus, in the case of prolonged growth, without access of free oxygen, yeast cells elongate, and at times are observed to 166 THE TECHNOLOGY OF BREAD-MAKING. be several times as long as broad (sausage-shaped). The same peculiarity of outline may be noticed in yeast that has been grown in sweetened water. The reason may be that, with a deficient supply of nutriment, each cell stretches itself out, as it were, in order to expose as great a surface as possible to the medium. It is well known that the area of surface of a sphere is less in proportion to its cubical contents than is that of a cylinder or of any other solid body. By offering a greater surface to the liquid in which it is growing, the yeast cell presumably is enabled to absorb a greater amount of nutri- ment. In breweries where sugar is largely used as a substitute for malt the yeast suffers from the low percentage of nitrogenous matters contained in the wort : the result is that such yeast has little vitality and is soon exhausted. Large quantities of mineral salts also effect the shape of the yeast cell ; thus, the yeast of Burton ale is oval (egg-shaped) in outline : the Burton water is extremely hard, containing calcium sulphate in large quantities. Badly nourished yeast, on examination, is usually found to have abnor- mally thin and fragile cell walls, these being broken by the slightest pressure ; the contents of the cells are also thin and watery, instead of full of healthy granulations of gelatinous protoplasm. 313. Sporular Reproduction of Yeast.— In addition to the budding process already described, yeast also reproduces, when deprived of all nour- ishment by the formation of spores within the cell. To observe this effect, prepare first a block of plaster of Paris by taking some of the powder, rapidly making it into a thin paste, and then pouring same into a cardboard mould. Let it set and then strip away the cardboard. Smear on the smooth surface of tlie plaster a little pressed yeast which has been previously washed in distilled water Place the block with yeast face upwards in a shallow dish, and pour in water until its surface is just a little below that of the yeast. Cover it over with a glass shade to keep out dust, etc., and stand in a warm place (about 20-25° C.). Each day remove a little and examine under the microscope ; after a few days some of the cells will show denser masses of protoplasm aggre- gated around from two to four points. These gradually grow, and at last occupy the whole of the interior of the cell. They become coated with cell envelopes, and then constitute ascospores. The walls of the ascus or mother-cell after a time dis- appear, and the liberated spores perform tlie functions of yeast, inducing fermenta- tion and reproducing by the ordinary mode of budding. Among the con- ditions necessary for spore formation are young and vigorous cells, com- narative absence of nutriment, and a fairly warm temperature. The speed of spore formation is greatly influenced by the latter condition ; within ^rtam limits increase of temperature quickens the formation of spores. This is also termed multiplication by endogenous division. Cells containing ascos- pores are sliown in Fig. H, which represents the first stages of development of the snores of S. Cerevisiee I., after Hansen : a, 6, c, d, e contain rudi- ments of spores, with the walls not yet distinct ; /, g, h, i, j are completely develpped spores with distinct walls. 314 Substances inimical to Alcoholic Fermentation.— Dumas has care- fully investigated the action of foreign substances on alcoholic fermenta- tion • Schutzenberger quotes largely from his rsults ; the following data obtained by Dumas are taken from the English translation of Schutzenber- ger’s work^ In the first place, a series may be given of those bodies which Fig. 11. — Ascospores. FERMENTATION. 167 retard, and when in sufficient quantity absolutely arrest, fermentation, These include the mineral acids and alkalies (phosphoric acid excepted), soluble silver, iron, copper, and lead salts ; free chlorine, bromine and iodine, alkaline sulphites, and bisulphites of the alkaline earths, manganese peroxide ; essences of mustard, lemon, and turpentine ; tannin, carbolic acid (phenol), creosote, salicylic acid ; sugar in excess, alcohol when its strength is over £0 per cent. ; and hydrocyanic and oxalic acids, even in small quantities. Phosphoric and arsenious acids are inactive. Sulphur has no effect on fer- mentation, but the carbon dioxide gas evolved contains from one to two per cent, of sulphuretted hydrogen. As may be gathered from the statement of the chemical changes produced by yeast, that substance gives always a more or less acid reaction. Dumas states that this acidity requires, for its neutralisation, alkali, equivalent to 0 *003 grams of normal sulphuric acid per gram of yeast. In his experiments he added various acids to yeast in proportions of from one to a hundred times the normal acid of the yeast. In this manner was determined the retarding or other action of the various acids on fermentation. Similar experiments were made with bases, and also salts ; with the latter, saturated solutions were first made ; the yeast was allowed to soak in these for three days, and then its fermenting power tested by its action on pure sugar. Dumas divided the salts into four groups. First, those under wdiose influence the fermenta- tion of the sugar is entire, and more or less rapid ; second, those which permit partial but more or less retarded fermentation ; third, those which permit the sugar to be more or less changed, but without fermentation ; fourth, those that prevent both change and fermentation. Alum is placed in the first of these classes, borax in the second, and sodium chloride (salt) in the third. Strychnine has no effect on the properties of yeast. For a detailed account of Dumas’ results the student is referred to Schiitzenberger’s work. 315. Isolation of Yeast and other Organisms. — ^As a preliminary to the study of varieties of yeast, it is absolutely necessary to have some means of separating and growing each variety in a state of absolute purity. Pas- teur did an enormous amount of work in this direction ; but the crucial point in all such investigations as these is the purity or otherwise of the yeast used to commence the experiment ; in all Pas- teur’s researches he used an apparatus which afforded most excellent means for the prevention of the incursion of foreign germs during his growth ; but he does not give us an absolutely certain method of obtaining a perfectly pure yeast to start with. In flasks of special construction, well known as “ Pasteur’s Flasks ” (Fig. 12), Pasteur introduces wort, then sterilises the same by boiling it, and afterwards sows therein a small quantity of the yeast he wishes to cultivate in the pure state. The Pasteur’s Fasks have a long narrow neck, which, as shown in the illustration, is bent twice on itself, the end being stopped with a plug of cotton wool. In addition, there is a side tubulure, stopped with india rubber tubing and a glass plug. The wort is introduced through the side tube, and when boiled the steam escapes through the bent tube. On cooling, the air which enters is sterilised by filtration through the cotton wool. The yeast is sown during a momentary removal of the glass plug. On the com- pletion of this fermentation, a little of the new growth of yeast is taken Fig. 12. — “ Pasteur’s Flask.” 168 THE TECHNOLOGY OF BREAD-MAKING. and transferred with all due precautions to a second Pasteur's Flask of steri- lised wort, and there again fermented. The yeast was grown in this way again and again, until the experimenter was of opinion that the preponderat- ing growth of the yeast would have crowded out of existence any foreign germs. To further aid in accomplishing this object, Pasteur also introduced in his growth-flasks some substances inimical to the organisms he wished to exclude, or else worked at a temperature specially favourable to the particu- lar organism whose growth he desired to favour. The yeast obtained in this manner he terms pure yeast ; undoubtedly this may be possible, and in many experiments was probably the case ; but it is nevertheless only a possibility we have to deal with, for the germs of foreign organisms may not be really dead, but only present in smaller quantity and in a weaker condition. More recent investigators have described methods by which it is possible to culti- vate and develop the growth of yeast from one single isolated cell ; in this manner giving the surest guarantee of the actual purity of the yeast produced. A first step in this direction is the adoption of what is known as “ Naegeli's Dilution Method," which is based on diluting down the liquid under examin- ation until a single drop will, on the average, contain but one organism. This may be accomplished in the case of yeast by taking a drop of the mixture of yeast and water, diluting it down considerably with water previously steri- lised by boiling, until the number of cells present in a drop can be counted under -the microscope. If these are estimated, for instance, to be about one hundred, then this liquid is further diluted to a hundred times its volume. Every precaution must be taken to sterilise all vessels and liquids used in the operation. Each drop of this ultimate dilution of yeast should contain one cell only. Ten drops are then placed in 20 c.c. of sterilised water, and thoroughly agitated. One c.c. is then placed in each of 20 separate flasks containing culture fluid, which may, for example, be sterilised wort. The probability is that ten out of the twenty flasks will contain but one organ- ism only, the others remaining unimpregnated. But here again it is only a balance of probabilities, and no certain inferences may be drawn. Hansen proceeded a step further by showing that, if the inoculated flasks are vigor- ously shaken, and then allowed to stand, the yeast cells will sink to the bottom and attach themselves to the sides of the flask. If more than one cell be present, the probabilities are that they vdll lie on the bottom some dis- tance apart. After some days the flask is raised carefully, and each yeast cell will be the centre of a small white speck visible to the naked eye, and consisting of a colony of yeast. If only one such speck be found, the flask con- tains a pure culture from one cell only. Subsequent cultivation may proceed on the lines laid down by Pasteur. Koch, in his experiments on Bacteria (certain minute organisms to be hereafter described), used specially prepared gelatin as a cultivating medium. The material was mixed with water until it acquired such a consistency as to set, when cold, into a jelly, which became fluid at a temperature of 35° C. lYr a cultivation experiment some of the gelatin is melted, a few of the bac- teria are taken out on the point of a needle and added to the gelatin. They are then diffused by shaking up the mixture, which is next poured out upon a flat surface properly protected. After some hours, a separate and pure cul- ture is obtained from each single bacterium present. On taking a minute particle from one of these little culture spots, and again sowing it in gelatin, a single species of bacterium was obtained. It was by experiments based on this principle, but carried out with most special precautions, that Koch iso- lated and exhaustively studied the ''Comma Bacillus'' of cholera, so inseparably associated with his name. Hansen modified this method for yeast culture, using, instead of Koch's nutrient gelatin (which consisted usually of meat broth and gelatin), a mix- FERMENTATION. 169 ture of hopped wort and gelatin. In a bright hopped wort of about 1058 gravity is dissolved from 5-10 per cent, of gelatin, the quantity being regulated so as to cause the mixture to “ set ” at 30-35° C., being solid below, and liquid above those temperatures. This mixture must, of course, be thoroughly sterilised. Some of the yeast which it is desired to cultivate is first diluted doum by the Naegeli method until of a convenient degree of dilution. This must be ascertained by experience : a drop of this solution is next taken by means of a sterilised piece of platinum wire, and transferred, wire and all, to a flask containing some of the treated gelatin preparation. This is agitated, so as to secure thorough mixture, but at the same time the production of froth must be avoided. A drop of this gelatin is taken out and examined micro- scopically to determine whether a sufficient number of yeast cells are present. Should they be too crowded, the contents of the flask are diluted with more gelatin ; if too few are present, some more must be taken from the yeast- containing flask by means of another piece of platinum wire. To cultivate the yeast, a modification of Koch's glass-plate known as Bottcher’s moist chamber, is employed. The chamber consists of a microscope slide, on which is cemented the glass ring, c, the upper surface of which is ground flat. In use, a small Fig. 13. — Bottcher’s Moist Chamber. a, Thin Cover-glass ; b, Layer of Nutritive Material ; c, Glass Ring ; d. Layer of Sterilised Water. quantity of the gelatin and yeast, as prepared above, is placed on the under side of the cover-glass. The upper edge of the glass ring is smeared with vaseline, and a few drops of water placed in the bottom of the chamber. The cover-glass and gelatin is placed on the ring and gently pressed down, when the vaseline makes a tight joint between it and the chamber. Each yeast cell embedded in the gelatin can now be subjected to microscopio examination, and any particular one kept under observation. To do this, any of the devices in common use as finders for any particular part of a microscopic object may be employed, but a very convenient one is Klonne and Muller’s marker, which consists of an appliance that can be screwed con- centrieally into the screw of the microscope which carries the objective. The desired cell is brought into the centre of the field : the objective is removed and the marker substituted for it. By means of the focussing screw it is lowered gently on to the cover, on which it marks a small ring encircling the cell required to be kept under observation. The cell is allowed to develop until a visible colony is formed. By means of a sterilised piece of platinum wire it is now picked off, and used to seed a prepared culture solution in a Pasteur’s or other flask. This operation of transference may be conducted in a dust-free room in the open air, but preferably in a small eupboard kept for the purpose, the walls of which have been moistened with glycerin, so as to maintain the interior as a germ-free space. The apparatus, and the hands of the operator, are introduced through a door just sufficiently large to provide for their admission. Large cultures are made, as before, by successive transferences to larger flasks. Hansen’s experiments on the effect on brewing, of specific varieties of yeast, were made with cultures obtained in this manner from single cells. 170 THE TECHNOLOGY OF BREAD-MAKING. 316. Classification of Yeasts. — In classifying yeasts as a genus of the fungi, they have received the following definition, based upon that of Rees. Classification of the Genus Saccharomyces. Budding Fungi, mostly without a mycelium, the individual species of which occur with cells of different form and size. Under certain treat- ment, and sometimes also without any previous treatment, cell-nuclei are seen. Under certain conditions the cells develop endogenous spores ; the germinating spores of most species grow to budding cells ; in exceptional cases a promycelium is first formed. Number of spores I to 10, most fre- quently I to 4. Under favourable conditions the cells secrete a gelatinous network, in which they lie embedded. The greater number of the species induce fermentation. The following is a list of the more important species : — Saccharomyces cerevisice . . ,, Minor ,, Ellipsoideus „ Pastor ianus. 317. Saccharomyces Cerevisae, or Ordinary Yeast. — At least two distinct varieties of ordinary yeast are known, to which the names of “ High and “ Low ” yeast have been given. The former of these is the common yeast of English ale fermentation ; the other, that of the well-known “ lager beer of continental production. Saccharomyces minor, a species of yeast found in leaven, is also possibly a sub-variety of S. cerevisice, so, too, is the distillers' yeast made in this country, and also imported from Holland and France, and sold as compressed yeast. 318. High Yeast . — This variety is so-called beeause of its ascending to the top of the fermenting liquid during fermentation. It consists of cells mostly round or slightly oval, from 8 to 9 /x in diameter, and answering generally to the description of yeast given in paragraphs 301 and 302. Illustrations of Brewers' High Yeast, Distillers' Yeast, and Bakers' Patent Yeasts are given in Plate II., to which reference is also made in Chapter XII. 319. Low Yeast. — ^Sedimentary yeast, or the “ low " variety of Saccharo- myces cerevisice, is that used in the manufaeture of lager beer. In general properties it much resembles the high yeast which has already been studied. In form the cells are somewhat smaller, and also rather more oval than those of normal high yeast ; but differ very little in shape from high yeast when grown, as at Burton, in very hard waters. Fig. 9, paragraph 301, gives illustrations of low yeast. 320. Distinctions between High and Low Yeast. — ^Whereas high yeast rises to the surface of the liquid during fermentation, “ low " yeast always falls to the bottom, and forms a sediment there ; hence the name “ sedi- mentary " yeast. Brewing with low yeast is performed at much lower temperatures than with high ; thus, whereas with the latter pitching tem- peratures of 20° or 21° C. (68° or 70° F.) are employed, the lager beer brewer starts his fermentation at as low as 8°C. (47° F.), or even 6°C. (43° F.). Working with this low temperature, fermentation proceeds much less rapidly than with high yeast ; growth and reproduction proceed more slowly, and tlie budding gives rise to less extensive colonies of cells. As Pasteur aptly ( High Yeast. 1 Low Yeast. Ferment of Leaven. Ferment of Wine. Plate II. J^re-yrars’ . Iiakjer.< 7c(tent Y£,ffs & law ) Various “Foreign” Yeasts. 175 176 THE TECHNOLOGY OF BREAD-MAKING. the growth of this fungus proceeds with extreme celerity, the mycelium first formed being thrown into folds by its rapid development ; at the same time considerable heat is produced. Microscopic examination shows that Myco- derma vini is very like yeast in appearance ; for a long time it was supposed that the two were identical, and that the mouldiness of beer was produced by the yeast cells ascending to the surface, and there developing as a fungoid growth. The two organisms are, how- ever, distinct species, and have not been transformed one into the other. My coderma vini during its growth seizes oxygen with great avidity, entirely preventing, during the period of its actual life, the development of other organisms also requiring oxygen, but endowed with less vital energy. Pas- teur states that on submerging this mould during its actual growth into malt wort, or other saccharine liquid, it for a short time causes fermentation, with the production of small quantities of alcohol ; but this action soon ceases with the early death of the fungus. In addition to this limited fermentative action, Mycoderma vini acts on wines and beers as a somewhat powerful oxidising agent ; it conveys the oxygen of the air to the alcohol of the liquid, causing its complete slow combustion into carbon dioxide and water,, and consequently rapidly lessening the alcoholic strength of the medium. Although wines and beers become sour simultaneously with the development of Mycoderma vini, the souring is not due to this organism, but to another distinct growth. The limited alcoholic fermentation produced hj Mycoderma vini leads to- its being classed among the saccliaromyces. 327. Hansen on Analysis of Yeasts. — It is principally due to the researches of Hansen that we are able to classify yeasts into species and races with such accuracy as is now possible. The results of his work have had such important effects on the brewing industry, and indirectly on that of bread-making, that the present book would not be complete without some reference to these classical investigations. Hansen's fundamental idea was that the shape, relative size, and appear- ance of yeast cells, taken by themselves, were not sufficient to characterise a species, since the same species under different external conditions could assume very different forms. Further, although, for example, a microscopic field of pure S. cerevisice could be distinguished by its appearance from pure S. pastorianus, yet in a mixture of the two it is not possible to distinguish indi- vidual cells of the one from those of the other. S, cerevisice forms at times sausage-shaped cells, while S. pastorianus occurs to a certain extent as round' or oval cells. Some other method, then, than microscopic examination is necessary for their differentiation. 328. Formation of Ascos pores. — By investigation of the conditions under which different races of yeast formed ascospores, Hansen was enabled to arrive at a mode of analysis of yeasts. A description of the mode of pro- cedure by which ascospores are obtained has already been given, but Hansen ascertained with more exactitude the precise conditions necessary, and thus sums up his conclusions : — The cells must be kept moist and have a plentiful Fig. 15 . — Mycoderma cerevisice. From Copenhagen Breweries. PlAT£ IV. Farmation of Ascoepores I . Saucch cer'ortetce I. 2. . Soucchj . Pcustcrruiruis I . 3. Sauced PcLSWf^tanujS 11 . A. Soucchi . J^astxrriciTia^ in . 5 . ScLcchj. eUXpsotdbt;cu6 I 6 . Scucch'. cUlpsoidezhe II . ( alter llaJiserv x 2000 . ) 177 N 178 THE TECHNOLOGY OF BREAD-MAKING. supply of air ; further, to form spores they must be young and vigorous. For most species a temperature of 25° C. is the most favourable ; for all species this temperature favours their development. Hansen found the process of spore-formation to vary in different species. S.S. cerevisice, 'pastorianus, and ellipsoideus germinate into spores in essen- tially the same way. S. ludwigii and 8. anomalus have each a separate and distinct mode of spore growth. While all species form spores at 25°, Hansen set himself to determine whether with different species there was any difference in their behaviour under varying conditions of temperature. In making observations, he regis- tered the time when the cells first showed distinct indications of spore forma- tion. The limits of temperature for all species are between from 0*5 to 3°G. and 37*5° C. At the highest temperature all species develop first indications in about 30 hours, and show very little difference in time at 25° C. ; but with lower temperatures very evident differences occurred. Hansen also found that there were differences in anatomical structure of spores that could be utilised for analytic purposes. In the so-called cultivated yeasts, 8. cere- visice employed for brewing, the spores have a distinct membrane, with non- homogeneous granular contents and a definite vacuole.- In the case of the so-called wild yeasts, the spore wall is frequently indistinct, the cell contents homogeneous, and the vacuole absent. Hansen investigated very closely the following six species of yeast, par- ticulars of which are furnished. Illustrations of the formation of ascospores are given in Plate IV. 8accharomyces cerevisice /., Enghsh top -fermentation yeast. Ferments glucose and maltose very vigorously. Spores strongly refractive to light, V alls very distinct ; size, 2*5-6 /x. 8, pastorianus /., Bottom-fermentation yeasts ; frequently occurs in the air of fermenting rooms ; imparts to beer a disagreeable bitter taste and un- pleasant odour ; can also produce turbidity and interfere with clarification in fermenting vat. Size of spores, 1*5-5 ju,. 8. pastorianus //., Feeble top-fermentation yeast ; found in air of breweries ; apparently does not cause diseases in beer. Size of spores, 2-5 p. 8. pastorianus III., Top-fermentation yeast, one of the species which produce yeast-turhidity in beer ; but in certain cases clarify opalescent w'orts. Size of spores, 2-5 p. 8. ellipsoideus /., Bottom-fermentation yeast ; occurs on ripe grapes. Size of spores, 2-4 /x. 8. ellipsoideus II., Usually bottom-fermentation yeast ; causes yeast turbidity, more dangerous than 8. pastorianus III. ; also imparts a sweetish, disagreeable, aromatic taste to beer, and a bitter, astringent after-taste. Size of spores, 2-5 y,. It will be noticed that Hansen sub-divides both 8. pastorianus and ellip- -soideus. He also sub-divides other species into different races or varieties. The leading points of connection between temperature and spore formation are given in the following table : — FERMENTATION. Temperature and Spore-Formation of Yeasts. 179 Sacch. Cerev. I. i Sacch. ' Past. 1- Sacch. Past. II. Sacch. Past. III. Sacch. Ellip. I. Sacch. I Ellip. II. Highest limit of development. Temperature of . . 37-5° I 31-5° 29° 29° 32-5° 35° Most rapid development. Temperature of . . 30° i 27-5° 25° 25° 25° 29° Most rapid development. Time, in hours, of appear- ance of first indication of spores 20 i i 1 24 25 28 21 22 Time, in hours, of appearance of first indications at 15° C. 110 50 48 48 45 ' 62 Lowest limit of development. Temperature of . . . . 9° 0-5° 0-5° 4° 40 1 4° It will be seen that considerable differences exist between the various yeasts in the particulars given. In addition, Hansen has also investigated the conditions of film formation and other properties which aid in the task of yeast differentiation. 329. Detection of “ Wild ” Yeasts. — In utilising spore formation, cultures are'^made at temperatures of 25° and 15° respectively, the latter being exam- ined after three days — 72 hours. All the wild yeasts will have commenced to show indications, while the cultivated yeast will be free from them. When used practically for technical purposes, this method is capable of detect- ing with certainty an admixture of 0 *5 per cent, of a wild yeast in an other- wise pure culture. For this and other tests applied to yeast by Hansen's methods, it is essential that the preliminary trials of the yeast be uniform, so as to make the tests comparative. 330. Varieties of Cultivated Yeast. — ^Not only have distinctions been drawn between cultivated and wild yeasts by the methods just described, but also well-marked and distinct varieties of cultivated yeast have been grown. Each of these possesses distinct characteristics, and is valued for certain kinds of beer. Thus, Jorgensen, for 'practical purposes, classifies different races of yeast prepared by pure culture methods in his laboratory into the following groups : — A. — Bottom-Fermentation Species. 1. Species which clarify very quickly and give a feeble fermentation in the fermenting vessel ; the beer holds a strong head. The beer, if kept long, is liable to yeast-turbidity. Such yeasts are only suitable for draught- beer. 2. Species which clarify fairly quickly and do not give a vigorous fermen- tation ; the beer holds a strong head ; high foam ; yeast settles to a firm layer in the fermenting vessel. Beer, not particularly stable as regards yeast- turbidity. Yeasts are suitable for draught-beer, and partly for lager beer. 3. Species which clarify slowly and attenuate more strongly ; the beer has a good taste and odour ; the yeast deposit is less firm in the fermenting vessel. Beer is very stable against yeast-turbidity. These yeasts are suit- able for lager beer, and especially for export beers which are not pasteurised or treated with antiseptics. 180 THE TECHNOLOGY OF BREAD-MAKING. B. — ^Top-Fermentation Species. 1. Species which attenuate slightly and clarify quickly. The beer has a sweet taste. 2. Species which attenuate strongly and clarify quickly. Taste of beer more pronounced. 3. Species which attenuate strongly, clarify slowly, and give a normal after-fermentation. The beer is stable against yeast-turbidity. Hansen has isolated two yeast races from ordinary yeast, both of which are employed in the Carlsberg breweries ; these are known as Carlsberg No. I. and Carlsberg No. II. Each has distinct properties of its own ; thus. No. I. gives a beer well adapted for bottling, containing less carbon dioxide than No. II., and possessing a lower degree of attenuation ; well adapted for home use. No. II. is principally cultivated for export, giving a good draught-beer containing more carbon dioxide. Passing for a moment the work of different investigators in review, Pasteur freed yeasts from weeds or foreign vegetable growths of the bacteria group. Hansen first eliminated wild yeasts as a fruit grower might elimin- ate crab-apples and other wild fruits from his orchard. Lastly, he has de- voted his attention to the growth of distinct breeds of cultivated yeast, each specialised for a particular type of beer. Jorgensen’s recent experiments carry the analogy a step further. He finds that among the progeny of a single yeast-cell, cells can be selected which may show important differences in respect of the taste, smell, and other properties of the fermented liquid. Such cells may, in fact, differ from each other as do children of the same parents. In yeast factories much the same is being done for'the bakers. Yeasts are selected for their vigour and capacity for fermentation, and these are culti- vated to the exclusion of types incapable of yielding such excellent results. Thus Lindner has introduced a variety of pure culture yeast in most of the distilleries of Germany, under the name of Race II. The results have been good. A further development on the same lines is the employment of pure cultures of the bacillus of lactic acid in distilleries. As subsequently de- scribed, this serves to inhibit excessive development of lactic acid itself, and butyric acid fermentation. Race V. has been specially recommended for this purpose. Experimental Work. 331. Substances produced by Alcoholic Fermentation. — Prepare some ten or twelve ounces of malt wort, by mashing ground malt in five times its weight in water ; and take its density by a hydrometer. To the wort add a small quantity of either brewer’s or compressed yeast, place it in a flask arranged with a cork and leading tube, and set it in a warm place C.) . Attach the leading tube to a flask containing lime-water, so that any gas evolved by the yeast has to bubble through the liquid. Notice that after a time fermentation sets in, and that the yeast rises to the top ; gas bubbles tlirough the lime-water and turns it milky, thus showing that carbon dioxide is being evolved. When the liquid becomes quiescent through the cessation of fermentation, again take its density with the hydrometer, notice that it is less than before ; return the liquid to the flask, and connect to a Liebig’s condenser and distil ; notice that the first drops of the distillate have the appearance of tears, as described in paragraph 100, Chapter III. Cease dis- tilling when about one-tenth of the liquid has distilled over ; notice that the distillate has an alcoholic or spirituous odour. Test it for alcohol by the iodoform reaction. FERMENTATION. 181 332. Microscopic Study. — ^Proceed with this on the lines of paragraph 301. Mount a trace of the yeast in a little warm malt wort, and examine care- fully : notice alteration in appearance of the yeast cells as they set up fer- mentation : keep the microscope with slide in focus for some time in a warm place, and observe from time to time the changes as they proceed. Watch specially for the development of budding, and as soon as any signs are de- tected watch the cell at short intervals until the bud has become completely detached from the parent cell. Sow a little yeast in a beaker in a small quantity of wort ; take out a little and examine under the microscope a few hours later : examine again on each successive day until some three or four days have olapsed since the fermentation has ceased. Note during the height of the fermentation the colonies of cells, sketch some of these : observe the clear outlines and trans- parent protoplasm of the new cells as compared with the shrunken appear- ance of the parent cells. As time proceeds, notice the gradual alteration in appearance of the yeast, until at last the new cells are similar in appearance to those originally sown. Study sporular reproduction as directed in paragraph 313. CHAPTER X. BACTERIAL AND PUTREFACTIVE FERMENTATIONS. Moulds. 333. Schizomycetes. — Grove defines the Schizomycetes or “ splitting fungi ” (Spaltpilze) as being unicellular plants, which multiply by repeated subdivision, and also frequently reproduce themselves by spores, which are formed endogenously. They live, either isolated or combined in various ways, in fluids and in living or dead organisms, in which they produce decompositions and fermentations, but not alcoholic fermentation. Among these organisms are included bacteria, bacilli, vibrios, etc., but comparatively few of these have an immediate bearing on the present subject, and so the great majority need not here be described. a, Cocci ; b, Diplococci and Sarcina ; c. Streptococci ; d, Zoogloea ; e, Bacteria and Bacilli ; /, Clostridium ; g, Pseudo-ftlament, Leptothrix, Cladothrix ; h. Vibrio, Spirillum Spirochsete, [and Spirulina ; t, Involution- forms ; k. Bacilli and Spirilla, with cilia or flagella ; I, Spore-forming Bacteria ; m, Germination of the Spore. The difficulty of classifying the Schizomycetes increases with a more minute acquaintance with these organisms, as investigation shows that one and the same organism occurs in varying forms under different con- ditions. Some of the various growth-forms are illustrated in Fig. 16. If, on the other hand, grouped according to the chemical changes they produce, then in many mstances more than one organism is found capable of inducing the same chemical reaction. For the purposes of the present work, it will be more convenient to accept provisionally a classification according to chemical effects produced. The Schizomycetes possess the property of surrounding themselves with 182 BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 183 a gelatinous substance, in which large colonies of them may be seen im- bedded. They are then said to be in the “ Zoogloea '' stage. 334. Bacteria. — ^These organisms consist of small cells, commonly cylindrical in shape ; they increase by transverse divisions of cells, and reproduce by sporulation. Bacteria have a spontaneous power of move- ment. Organisms of Putrefaction. 335. Bacterium Termo. — ^This is essentially the ferment of putrefaction. It is present in air, and also in waters contaminated with sewage. Hay, meat, or flour infusions, malt wort and other liquids, on being exposed to the atmosphere, become turbid, and are then found on microscopic examination to be densely crowded with bacteria. The cells are oval in shape and about 1*5 to 2 mkms. in length : they are constricted in the middle, giving them a sort of hour-glass appearance ; at each end is an extremely fine filament, termed a “ flagellum,” and sometimes a “ cilium.” This is probably the organ by which the bacterium exerts its motile or moving power. For illustrations of this and other forms of bacteria see Plate V. This definite movement of the bacterium must not be confounded with the simple oscillatory movement of small particles of matter when sus- pended in a fluid. This latter may be observed by rubbing up a little gamboge in water, and microscopically examining a drop of the liquid : the small solid particles are seen to be in a continual state of motion. This latter is termed the “ Brownian ” movement. The spores of the bacteria, in common with most other of those of the- schizomycetes, are extremely tenacious of life. They may be dried up and exist in a dormant state for an indefinite time without losing their vitality ; for immediately on being again moistened and placed in a suitable medium, they commence an active existence and cause putrefaction. The dry spores are not destroyed by even boiling them for so long as a quarter of an hour ; they are also not affected by weak acids. 336. Bacilli. — ^The word bacillus literally means a stick or rod, and is applied to the organisms of this genus because of their rod-like shape.. The cells are long and cylindrical and occur attached to each other, thus forming rod-like filaments of considerable length. There is little or no constriction at the joints, which with low microscopic powers are scarcely observable. They increase by splitting transversely, and reproduce by spores. Bacteria and bacilli are closely allied genera, some species of the one closely resembling species of the other. In the very long cells of bacteria the transverse divisions may be detected, while in the equally long cells of bacilli no traces of division can be seen. Bacilli are sometimes motile, but after a time pass into a condition of rest, or zoogloea stage. The long threads of bacilli often assume a zig-zag or bent form ; and unless sub- jected to very careful examination, appear to be continuous. Pasteur's filaments of turned beer “ consist of bacilli.” 337. Bacillus Subtilis. — ^This organism is also termed “ Vibrio subtilis,” and is largely present in air. Owing to its being the predominant organism produced when an aqueous infusion of hay is exposed to the air, it is fre* quently referred to as the bacillus of hay. The cells are cylindrical, and grow to about 6 mkms. in length, and are provided with a fiagellum at either end. They usually occur adherent to each other, forming long filaments, as shown in Plate V. Plate V Fig. 1 Fig. 2 , Ch PcLSVeur b IdhtPienvs Sr Lott. Fig: 5 . F^. BacxPbae suPuKxs (Cohn/ ) x 650. CLostriPbCarri/ hwtyri/xvnv (PraffrrujwPou) x 650 (oJboat/)^- Various Disease Ferments. 18 BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 185 The term “ vibrio,” applied to certain forms of schizomycetes, is derived from their appearing to have a wriggling or undulatory motion ; this •effect is illusory, being actually caused by their rotating on their long axis. An enlarged illustration of B. suhtilis is given in the following figure, 17. Fig. 17 . — Bacillus suhtilis X 4000 (after Ballinger). They increase by transverse division, and reproduce by spores. As the spore formation of B. suhtilis has been most carefully observed, a descrip- tion of its mode of reproduction will be of service as a type of that of the schizomycetes generally. In spore formation the protoplasmic contents of the cell accumulate at the one end, causing an enlargement there ; the rest of the cell after a time drops off and dies ; the mature spore may then live for even years without losing its vitality ; and being of extreme minute- ness, these spores permeate the atmosphere, and are ever ready to germinate on finding a suitable medium. In the act of germination the spore splits its membrane open, and a new rod grows and projects through the opening. The dry spores are extremely tenacious of life, and withstand boiling for an hour in water without losing their vitality. Some three or four consecu- tive boilings in a flask plugged with cotton- wool, with a few hours’ interval between, are necessary to ensure sterilisation from this organism. Various writers impute different specific fermentative actions to B. subtilis, but it is doubtful whether the production of any particular chemical compound should be associated with it. It is essentially the organism of putrefaction, and effects the decomposition both of nitrogenous and carbonaceous bodies with the evolution of mal-odorous gases. Both it and B. termo are stated to possess the power of peptonising proteins, this operation being a preliminary to their further conversion into leucin, tyrosin, and allied bodies. 338. Diastatic Action of Bacteria. — ^This latter action is a consequence of the property possessed by the bacteria of attacking protein bodies and eon verting them into peptones. Wortmann has devoted considerable attention to the investigation of the problem whether or not bacteria have any action on starch : whether or not, by the secretion of a starch-trans- lorming substance similar to diastase, or in any other but not clearly defined way, they are capable of transforming starch into soluble and diffusible •compounds. In order if possible to obtain a solution of this problem, Wortmann experimented in the following manner : — To about 20 or 25 c.c. of water a mixture of inorganic salts (sodium •chloride, magnesium sulphate, potassium nitrate, and acid ammonium phosphate, in equal proportions) was added to the extent of I per cent. The same quantity of solid wheat-starch was next added, and the liquid then inoculated with one or two drops of a strongly bacterial solution ; shaken, corked, and allowed to remain in a room at a temperature of 18° to 22° C. {Bacterium termo was the predominating organism in the inocu- lating fluids employed.) In from five to seven days, the first signs of commencing corrosion of the starch granules had become visible, the larger grains being first attacked, and much later, when these had almost com- pletely disappeared, those of lesser size. In a second series of experiments, soluble starch was substituted for 186 THE TECHNOLOGY OF BREAD-MAKING. the solid form, the progress of the reaction being watched by the aid of iodine. Samples taken from time to time exhibited at first the blue colour, then violet or dark red, passing to wine red, and finally, when the starch had disappeared, underwent no change. Wlieat-starch gvains are found to be by far the most readily attacked by bacteria when compared with other varieties, in several experiments having even completely disappeared before other sorts of starch were affected. Of a number of starches, that of potatoes alone entirely re- sisted attack. When wheat-starch in the solid state was mixed with starch solution or with starch paste, the solution became entirely (and the paste in greater part) changed before any action occurred on the solid granules. With regard to this unequal power of resistance shown by different kinds of starch, Wortmann concludes from his further observations that the difference of rapidity with which a given kind is attacked and dis- solved by a ferment is inversely proportional to its density, provided always that the granules in question are entire and uninjured by cracks or fissures. In the same way are explained the differences in point of time in which granules of the same kind are sometimes observed to undergo change accord- ingly as they are intact or otherwise. The cause of potato-starch, or of bean-starch, and even under certain conditions, wheaten starch, resisting attack, in spite of the abundant pres- ence of bacteria, is apparently to be sought for in the fact that other more easily accessible sources of carbon nutriment were also present, certain protein constituents of the potato slices, or of the beans employed affording this more readily than the starch granules, just as in the experiments above cited, with wheaten starch solution and solid wheaten starch, the former was preferentially attacked ; only after all, or at least the chief portion, of the proteins present had been used up, was the starch in these cases attacked. Another point was also established in the course of these experiments — that if air is excluded, no appearance of corrosion or solution of the starch granules is manifested. That the starch in the process became changed in part to glucose was easily ascertained by testing with Fehling’s solution, and a detailed series of experiments, made with a view to eliminating if possible the ferment itself, yielded evidence showing that bacteria possess the remarkable property of producing a starch-transforming ferment, only when no source of carbon other than starch is at their disposal, and this ferment is incapable of chang- ing albumin into peptone, just as in the case of diastase. The results of Wortmann's researches may be briefly recapitulated — 1. Bacteria are capable of acting on starch, whether in the solid state, as paste, or in solution, in a manner analogous to diastase. 2. As in the case of diastase, different kinds of starch are attacked by bacteria with different degrees of rapidity. 3. The action of bacteria on starch is manifested only in the absence of other sources of carbon nutriment, and when access of air is not pre- vented. 4. The action of bacteria on starch is effected by a substance secreted by them, and which, like diastase, is soluble in water, but precipitable by alcohol. 5. * This substance acts precisely as diastase in changing starch into a sugar capable of reducing cupric oxide, but is not possessed of peptonising properties. These results of Wortmann's are quoted at some length because of their bearing on the action of bacteria in dough. One most important point is, that the diastatic action of bacteria, or their secretions, only occurs BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 187 in the absence of protein matter, which is the substance most specially suited for the development of these organisms ; consequently, with the exception of the transformation of sugar more or less into lactic acid, the carbohydrates are unattacked by the schizomycetes during normal dough fermentation. The bacteria cause more or less change in proteins, but exert no diastatic action. These protein changes are, by the way, un- accompanied by any appreciable evolution of gas. It will be noticed that Wortmann expressly states that the bacteria have no peptonising action ; while it is also as expressly stated that they readily attack the proteins. He does not state what substances he finds produced by this action. The opinion is, nevertheless, very generally held that peptones are produced during changes which occur during the fermentation of dough, and it has been supposed that the bacteria were the active agents. Thus, Peters describes a bacillus which he found among the organisms of leaven which possesses a peptonising power. 339. Putrefactive Fermentation. — ^Putrefaction is that change by which most organic bodies containing nitrogen in a protein form are first resolved into substances having a most putrid odour, and ultimately into inorganic products of oxidation. Bacterium termo and B. subtilis have already been mentioned as the principal organisms of putrefaction. Pasteur divides the act of putrefaction into tw'o distinct stages, which it will be well here to describe. On exposing a putrescible liquid to the air, there forms on the surface a film composed of bacteria, etc. ; these completely exclude any oxygen from the liquid, by themselves rapidly absorbing that gas. Beneath, other more active organisms, which Pasteur groups together under the name of “ vibrios,’' act as ferments on the protein matters of the liquid, and decompose them into simpler products ; these simpler products are in their turn oxidised still further by the surface bacteria, Pasteur practically defines putrefaction, or putrid fermentation, as fer- mentation without oxygen. 340. Action of Oxygen on Bacterial and Putrefactive Ferments. — Pasteur draws a hard and fast line between certain bacteria which he affirms live in oxygen, and absolutely require it, and others to which oxygen acts as a poison ; to which latter class he states that the vibrios belong. This name is used by him seemingly to refer to those micro-organisms which are in active motion. Of the bacteria of the first type, he mentions that if a drop full of these organisms be placed on a glass slide, and examined with a microscope, there is soon a cessation of motion in the centre of the drop, while those bacteria nearest the edges of the cover-glass remain in active movement in consequence of the supply of air. On the other hand, if a drop of liquid containing the vibrios of putrefactive fermentation be studied in a similar way, motion at once ceases at the edge of the cover- glass ; and, gradually, from the circumference to the centre, the pene- tration of atmospheric oxygen arrests the vitality of the vibrios. Pasteur thus divides the bacteria into an aerobian and an anaerobian variety ; the former require oxygen, the latter find it a poison, and live and thrive best in its total absence. In proof of this view he describes experiments of a most careful character made by him. 341. Conditions Inimical to Putrefaction. — ^First and foremost among these is the keeping out of the germs of putrefactive ferments from the substance. Meat and protein bodies, generally, have come to be ordinarily viewed as very changeable substances, whereas in the absence of germ life they are very stable bodies. Putrefaction is the concomitant, not of death but of life. If animal fluids are drawn off into sterilised vessels 188 THE TECHNOLOGY OF BREAD-MAKING. without access of air, they keep for an indefinite length of time. Or the germs may be destroyed heat, when putrescible substances also remain unchanged. This latter is the basis of Appert's methods for the preser- vation of animal substances. These methods consist of exposing the substances to a sufficiently high temperature in hermetically sealed vessels ; or they may be heated in vessels so arranged that air may escape, but that any re-entering shall be freed from bacterial germs either by passing through a red-hot tube, or by being filtered through a thick layer of cotton-wool. Tinned meats, milk, etc., are preserved on this principle of ApperCs. Putrefaction may be arrested by intense cold, although even freezing bacteria does not destroy their power of inducing putrefaction when again warmed. As a consequence of this action of cold, meat when thoroughly frozen may be preserved almost indefinitely. The absence of water is another preventative of putrefaction. Vegetables and meat, if thoroughly desiccated, show, on keeping, no signs of putrefying. In the same way, yeast, although in the moist state one of the most putrescible substances known, may, by being carefully dried, be kept for months, not merely without putrefying, but also without destroying the life of the cell. 342. Products of Putrefaction. — These are exceedingly numerous and complex, among them may be found volatile fatty acids, but3n*ic, and other of the series ; ammonia, and some of the compound or substitu- tion ammonias ; ethylamine, trimethylamine, propylamine, etc. ; carbon dioxide, sulphuretted hydrogen, hydrogen, and nitrogen. Lactic and Other Fermentations. 343. Lactic Fermentation. — ^This is primarily the fermentation by means of which milk becomes sour. The chemical change is a very simple one. Milk contains the variety of sugar known as lactose or sugar of milk, C12H22O11. By hydrolysis, this splits up into two molecules of a glucose called lactose, galactose, or lacto-glucose, C6H12O6. When subjected to the influence of the lactic ferment, lacto-glucose is decomposed according to the following equation : — C6H12O6 = 2HC3H5O3. Lacto Glucose. Lactic Acid. Ordinary glucose, and also cane-sugar and maltose, are susceptible of the same transformation. From numerous recent researches, there is evidence of a number of organisms which possess the power of produc- ing lactic acid by the conversion of glucose. One or more of these is always found present in greater or less quantity in commercial yeasts, also on the surface of malt ; in the latter case it may be detected by washing a few of the grains in water, and then examining the liquid under the micro- scope. Its shape, according to Lister, when developed in milk, is shown in the accompanying illustration. When viewed with a lower power in a field of yeast, The lactic ferment appears as small elongated cells somewhat constricted in the middle, generally detached, but occurring sometimes in twos and threes ; their length is about half that of an ordinary yeast cell. When single they exhibit the Brownian movement. Lactic fermentation proceeds most favourably at a temperature of about 35° C., and is retarded and practically arrested at a temperature Fig. 18. — Bacterium lactis X 1140 (after Lister). BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 18J> ^A'hicli still permits the growth and development of the yeast organism, and consequent alcoholic fermentation. For this reason brewers always take care to ferment their worts at a low temperature, thus preventing the lactic ferment, which is always more or less present, from any rapid development. The other bacterial and allied ferments are also affected in a similar manner by temperature. Dilute solutions of carbolic and salicylic acids (and also hydrofluoric acid) greatly retard lactic fermen- tation, while in such very weak solutions they have but little action on the yeast organism ; hence yeast is sometimes purified by being repeatedly grown in worts, to vliich small quantities of these acids have been added. The most favourable medium for lactic fermentation is a saccharine solu- tion rather more dilute than that used for cultivating yeast, and containing proteins in an incipient stage of decomposition. The analogy between this fermentation and the alcoholic is close, because the two may proceed side by side in the same liquid. The presence of acid is inimical to lactic fermentation ; hence the fermentation arrests itself after a time by tho development of lactic acid ; provided this is neutralised from time to time by the addition of carbonate of lime or magnesia, the fermentation proceeds until the whole of the sugar has disappeared. In a slightly acid liquid, as for instance the juice of the grape, alcoholic fermentation pro- ceeds almost alone ; but with wort, which is much more nearly neutral (if made with good malt), lactic fermentation sets in with readiness, and consequently has to be specially guarded against. Some varieties of the lactic acid ferment require air for their growth and development, whilo others are anaerobic in their character. In addition to its specific action on glucose, converting it into lactic acid, the lactic ferment has other functions of importance in commercial operations ; thus, the presence of lactic ferment germs on malt result in the formation of a little lactic acid during the mashing ; in distillers’ mashes this is found to be somewhat valuable, and is encouraged, as it apparently helps to effect a more complete saccharification of the malt, and conse- quently increases the yield of alcohol. It also peptonises the proteins, bringing them into a condition more adapted for the nutrition of yeast. Distillers, therefore, frequently allow their malts to develop considerable- acidity before using them, find give new mash tuns a coating of sour milk before bringing them into use. In bread-making, by the Scotch system, the presence of the lactic ferment is deemed to make better bread : either the ferment, or the lactic acid produced, softens and renders the gluten of the flour more elastic. Hansen’s methods have been applied to the preparation of pure cul- tivations of lactic ferments, with the view of securing a more satisfactory acidification of cream preparatory to its being made into butter. Two distinct species have been isolated, which give particularly favourable results in butter-making ; one of these is stated by Storch to give a pure and mild slightly sour taste, imparting at the same time a very pure aroma to the cream and butter made therefrom. There are other lactic acid- forming bacteria, which, on the contrary, produce diseases in milk ; thus, one species causes the milk to become viscous at the same time as it under- goes lactic fermentation. Further, certain bacteria induce a tallow-like flavour in butter. Not only may we have a fermentation producing lactic acid as distinct from other acids, but also there are differentiations in the character of the secondary products formed at the same time as the lactic acid, and which secondary products affect most vitally the success or other- wise of the particular process from its manufacturing standpoint. It is more than possible that these variations in the nature of lactic fermentation itself may have a direct bearing on the success of bread-making operations. 190 THE TECHNOLOGY OF BREAD-MAKING. 344. Butyric Fermentation. — ^At the close of the lactic fermentation of milk, the lactic acid or lactic salts, as the case may be, seem to be acted on by ferment organisms and converted into butyric acid with the evolution of carbon dioxide and hydrogen — 2HC3H5O3 = HC4H7O2 + 2CO2 + 2H2. Lactic Acid. Butyric Acid. Carbon Dioxide. Hydrogen. Several species of bacteria are capable of inducing butyric acid fer- mentation. The most carefully examined among these is Clostridium hutyricum, known also as Vibrio butyricus, which occurs in the form of short or long rods, and is in shape and general appearance very similar to B. subtilis, differing, however, from that organism in that it contains starch. In breweries and pressed yeast factories, butyric fermentation is often caused by organisms of altogether different type to C. butyricum. This particular organism is anaerobic in character, but others of the species producing butyric acid are distinctly tolerant of oxygen. The general conditions of butyric fermentation are similar to those of lactic fermen- tation. A temperature of about 40 ° C. ( 104 ° F.) is specially suitable; the presence of acids is to be avoided ; or w 4 iere butyric fermentation is not wished, its prevention is more or less attained by working at a lower temperature and with a slightly acid liquid. However, with the fully developed organism, a slight acidity is unable to prevent butyric fermen- tation. Although butyric fermentation is usually preceded by lactic fermentation, the butyric ferment is also capable of acting directly on sugar itself, and also on starch, dextrin, and even cellulose. Tannin has a markedly prejudicial effect on the growth and develop- ment of bacterial life, hence the addition of this substance, or any com- pound containing it, to a fermenting liquid, exercises great preventive action on the development of lactic and butyric fermentation. Hops contain tannin as one of their constituents, and also the bitter principles of the hop cause a hopped wort to be much less liable to lactic fermentation than one unhopped. For a similar reason, bakers add hops to their patent yeast worts. 345. Acetic Fermentation. — Certain organisms effect the change of wine and beer into vinegar. The reaction is one of oxidation of the alcohol present : in the first place, aldehyde is formed, and then this body is oxidised into acetic acid, according to the following equations : — ■ 2C2H5HO + 02 = 2C2H4O + 2H2O. Alcohol. Oxygen. Aldehyde. Water. 2C2H40 + 02 = 2HC2H3O2. Aldehyde. Oxygen. Acetic Acid. Pasteur described under the name of My coderma aceti an organism through whose agency alcohol is oxidised into acetic acid. Hansen has detected two distinct species under this name, distinguished by the one staining yellow, and the other blue, with iodine solution. Both possess the same chemical properties, and in order to develop vigorously require a plentiful supply of oxygen. They are, in fact, strictly aerobic. A tem- perature of about 33 ° C. is the most favourable to the production of acetic fermentation. Bacterium aceti also converts propyl alcohol into propionic acid, but is without action on either butyl alcohol or the amyl alcohol of fermentation. Bacterium aceti forms a mycelium on the surface of liquids, pos- sessing a certain amount of tenacity : viewed under the microscope, this mycelium is seen to consist of chains of cells, as shown in Plate V. BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 191 In the substance known as “ mother of vinegar ” or the vinegar plant, long supposed to be identical with B. aceti, A. J. Brown discovered a separ- u,te organism, which, in addition to producing acetic acid, is also marked by the property of causing the formation of cellulose ; to this he has given the name of Bacterium xylinum. Peters has discovered in extremely old and sour leaven an acetic acid bacterium, distinct from those just described. The individuals are about 1 *6 /X long, and 0 *8 /x broad, truncated at one end, and tapering at the other. Interest attaches to the isolation of this specific organism, inasmuch as a small proportion of the acidity of bread is due to acetic acid. K temperature below 18° C. is almost inhibitory to the action of the acetic acid ferment, while most antiseptics, and especially sulphur dioxide, are exceedingly inimical to acetous fermentation. Jorgensen remarks that “ an important advance was made in our know- ledge of acetic bacteria when Buchner and Meisenheimer, as well as Herzog, proved that this remarkable fermentation is brought about by the activity of an enzyme. The cells may be killed with acetone, and then treated in the same way as the alcohol yeasts (see Chapter IX. , paragraph 289), and it can then be shown that, after evaporating the liquid, the residue can bring about the acetic fermentation, although it contains no living cells. By this discovery the real nature of the fermentation becomes clear. Like the alcoholic fermentation, it is caused by an enzyme, which may react independently of the living cell that brought it into existence."’ (Micro- organ' sms and Fermentation, Fourth English Edition.) 346. Viscous Fermentation. — ^Viscous fermentation is that variety -which causes “ ropy beer.” Pasteur supposed this to be due to an organism consisting of globular cells of from 1*2 to 1*4 /x in diameter, adhering to- gether in long chains. Moritz and Morris, who have devoted particular attention to this subject, disagree with Pasteur’s views, and ascribe ropi- ness principally to a ferment known as Pediococcus cerevisice. This organism occurs either in pairs of cells or tetrads (i.e., four cells arranged in the corners of a square), diameter of each cell being 0-9-1 -5 /X- These organisms are similar in appearance to those marked b, Fig. 15. Beer, after haviiig undergone this fermentation, runs from the tap in a thick stream ; and in very bad cases, a little, when placed between the fingers, pulls out into strings. A somewhat similar condition sometimes holds in bread, which then is termed ropy bread ; this is discussed very fully in Chapter XVIII. 347. Disease Ferments. — ^The ferments of lactic, viscous, and other than alcoholic fermentation, are frequently called “ disease ferments,” from their producing unhealthy or diseased fermentations in beer. 348. Spontaneous Fermentation. — ^In this country, alcoholic fermenta- tion is usually started by the addition of more or less yeast from a previous brewing ; it was formerly the custom to allow the fermentation to start of itself. This is said still to be practised in some parts of Belgium in the manufacture of a variety of beer, known as “ Faro ” beer. In manu- facturing such beers, the vats of wort are allowed to remain exposed to the air, and fermentation is excited by any germs of yeast that may find their way therein. It is possible that under such circumstances a wort may only be impregnated by yeast germs, in which case pure alcoholic fermentation alone will be set up. It is far more likely, however, that germs of lactic ferment and other organisms will also get into the wort ; consequently the beer will be hard or sour, and also likely to speedily be- 192 THE TECHNOLOGY OF BREAD-MAKING. come unsound. On the other hand, grape juice is always allowed to fer^ ment spontaneously, but then this liquid is distinctly acid, through the presence of potassium bitartrate ; and acidity retards or prevents bacterial fermentation. Bakers’ barms or patent yeasts are at times allowed to ferment spon- taneously ; they are then found to contain a large proportion of foreign organisms, principally the lactic ferment. Except where very special precautions are adopted, they are liable to be uncertain in their action, and often produce sour bread. But in all cases of so-called “ spontaneous ” fermentation it must be remembered that the fermentation is due to the presence in the wort of yeast cells or spores that either have been introduced along with the malt and hops without being destroyed, or else have found their way into the wort from some external source, such as germs floating in the air. It is also frequently possible that a sufficient quantity of yeast remains about the fermenting vessel from the last brewing to again start fermentation. Moulds and Fungoid Growths. 349. The nature of these has been already referred to in Chapter IX. and the mould of beer, Mycoderma cerevisice, described and its properties explained. The moulds are all of them members of the fungus family. A few other varieties, because of their having more or less connection with the subject of this work, requires description. 350. Penicillium Glaucum. — This is the ordinary green mould of bread jam, etc. The base of this consists of a mycelium bearing both submerged and aerial hyphse. The upper ends of the aerial hyphsc terminate in a string of conidia or spores, which break off on the slightest touch ; these constitute the green powder which gives this mould its characteristic appear- ance. One of these spores, on being sowti in an appropriate medium, as hay infusion or Pasteur’s fluid, germinates and produces a young 'penicillium. The conidia retain their vitality for a long time, and from their extreme minuteness are readily carried about by the air ; hence substances that offer a suitable medium for the growth and development of moulds, become impregnated on being exposed to the atmosphere. Under favourable circumstances penicillium developes with extreme rapidity ; some few years since the barrack bread at Paris was attacked by this fungus, a few hours was sufficient for its development, and the mould was in active growth almost before the bread was cold. It is stated that the spores of this species are capable of withstanding the heat of boiling water, so that the act of baking an infested flour would not necessarily destroy the spores. 351. Aspergillus Glaucus. — This is another mould very similar to penicillium in appearance and colour, but having at the ends of its hyphse small globose bodies containing the spores ; these bodies being termed sporangia. 352. Mucor Mucedo. — This mould develops well on the surface of fresh horse dung ; this substance, if kept warm, will be found after two or three days covered with white filaments, these being the hyphse, and terminating in rounded heads or sporangia. In form M. mucedo somewhat resembles A. glaucus, but is distinguished from it by having a whitish aspect, A. glaucus being of a greenish colour. 353. Micrococcus Prodigiosus. — This organism consists of round or BACTERIAL AND PUFREFACTIVE FERMENTATIONS. 193 oval cells, from 0*1 to I mkm. diameter. These are at first colourless, but gradually assume a blood-red tint : they grow on wheat- bread, starch paste, etc. M. prodigiosus is the cause of the appearance known as blood-rain occasionally seen on bread : at times the growths proceed so far as to produce dripping blood-red patches on the bread. £ Fig, 19 . — Micrococcus prodigiosus, Cohn X 1200 (from nature). 354. Red Spots in Bread. — ^A phenome- non sometimes confused with the effect of M. prodigiosus, but nevertheless quite distinct therefrom, is that of intensely red-coloured spots in freshly baked bread. These are so bright as to lead to the suspicion that concentrated tincture of cochineal or other powerful dye had by accident got on to the dough and been baked with it. Fortunately for the baker, the occurrence of these spots is rare, and consequently there are few opportunities of minutely investigating them. So far as the authors' experience goes, the spots occur most fre- quently in bread made from flour of the very highest class, such as Hun- garian patents : they have also seen them in bread containing a large admixture of Oregon flours. The spots in bread do not increase in size as the bread grows old, nor are they apparently associated with any change in its constituents : there are no signs, in fact, of the colouration being due to the presence of any living and multiplying organism. It is exceed- ingly difficult to obtain specimens of the colour spots in unbaked dough, and only on one occasion has such a specimen come into the hands of one of the authors. In that case a small patch of dough was sent him while absent from home, and was only examined by him on his return after two days. The dough had then got a slight dry skin on, but there were no signs of any growth or spreading in the dough ; so far, therefore, as any con- clusion may be drawn from this, it is against the source of colour being any organism developing in the dough. Careful microscopic examination of coloured portions of the bread show in the fainter spots that while the starch is uncoloured, there is a red dyeing of the gluten. In the larger and darker spots there may be sometimes seen by the naked eye a nucleus, which is so dark in colour as to be almost black. On breaking down a little of this nucleus with water, and examining microscopically, the author has invariably found fragments of the outer integument of the grain. Among these have been detected portions of the outside layer of bran, showing its characteristic markings, and also hairs of the beard of the wheat, all of which are intensely coloured. In one sample, only cursorily examined some years ago, a number of filaments somewhat similar to cotton- wool were observed, but not identified ; these, too, were coloured a very deep red. No signs of fungus spores or other special organisms were observable, but spores might possibly be crushed in the breaking down with water. The lack of material for purposes of further examination has prevented the author from carrying these investigations beyond this point, and such tests as are here recorded were made a number of years ago. The most probable cause of the colour is its deposit on the outside of the grain after its removal from the husk and prior to its being milled. It is suggested as its possible source either some insect of the cochineal species, or an intensely coloured microscopic vegetable growth, such as a mould. These minute particles of outer bran carrying the colour on the surface are sufficiently fine to pass through the dressing silks, and so get into the flour. They would be so small as to be perfectly invisible in any ordinary examination by the naked eye. On being wetted the colour spreads and stains the surrounding 194 THE TECHNOLOGY OF BREAD-MAKING. gluten, hence the colour in the dough, which remains also and is seen most distinctly in the baked bread. 355. Musty and Mouldy Bread. — ^Mouldiness may be very often noticed in bread which has been kept for a few days : at times a loaf of one day's production will remain quite sound, while another will rapidly become mouldy. The Analyst, October, 1885, contains an article by Percy Smith, giving an account of some experiments made by him on musty bread. The bread when new had no disagreeable taste, but on the second day had become uneatable. Smith made a series of experiments, among Avhich were the following : — (а) Musty bread, one day old, soaked in v ater, enclosed between watch glasses. (б) Flour from which the bread was made, similarly treated. In six days a had begun to turn yellow, emitted a disagreeable odour, and began to assume a moist cheesy consistency and appearance. This portion was found to be swarming with bacteria. On 6 , mucor muceclo grew in abundance ; the flour ultimately dried up without further change. (c) Sweet bread similarly treated. Aspergillus glaucus appears, but no mucor, neither does the bread become cheesy nor evolve odour of musty bread. The following are Smith's con- clusions based on these and other experiments. “ Ordinary bread turns mouldy owing to the growth of A. glaucus. Musty bread, on the other hand, yields both A. glaucus and M. mucedo, and then undergoes putrefactive decomposition, becoming the home of vibriones and bacteria. These organisms, of course, can have nothing to do with the mustiness ; they only flourish because there is a suitable nidus for 'their growth. It is, however, curious that the musty bread should decay while the sweet bread should not, whilst the only apparent difference between them is in the growth of M. mucedo. The suspected flour pro- duces an abundant crop of mucor, but does not decay. This is no doubt due to the fact that starch is not so suitable a nidus as is dextrin for bacteria. Perfectly pure flour failed to decompose when kept between watch glasses, but when placed in a damp cellar readily became musty, and produced a crop of M. mucedo.” He further concludes that this fungus is the cause of the mustiness in the cases cited, although other species may possess similar properties. When the flour was baked into bread, the assimilation of moisture regenerated the fungus, thus causing the bread to become musty, for which result it is not necessary for the plant to arrive at maturity ; the disagreeable taste being developed as soon as flocci are visible under the microscope. Mucor has apparently a specific chemical action on bread that is not possessed by Aspergillus glaucus. Hebebrand has recently published the results of some investigations on mouldy bread. He infected some samples of rye bread from mouldy bread, the organisms being chiefly Penicillium glaucum and Mucor mucedo. These were kept for periods of seven and fourteen days, and similar samples at once dried for analysis. The results showed that the mould caused a considerable loss of substance, carboliydrate being converted into water and carbon dioxide. There was only a slight loss of proteins, but the loss of carbohydrates caused the percentage of proteins to appear much higher in the dry substance of the mouldy bread. The decomposed protein was converted into amides. The following numbers show the percentage composition (1) of dried fresh bread, and (2) of the dried mouldy bread : — BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 195 No. l. No. 2. Protein, Insoluble . . 9*75 per cent. 9-77 per cent. ,, Soluble 1-92 5-15. Maltose 1*54 5 ) 0-50 Dextrin 8-02 ?? 11-86 Starch . . 76-75 63-52 Fat . . . . 0-26 55 2-II „ ( Ash 1-44 55 2-41 Crude Fibre . . . . 0-05 55 2-47 356. Diseases of Cereals. — Certain disea ses to which the cereal plants are subject are due to parasitic fungoid growths. Among these are mildew, smut, bunt, and ergot. Their nature may briefly be considered at this stage of our work. 357. Mildew. — ^To the farmer this blight is unhappily too familiar ; if a wheat field be examined in May or June, a greater or less number of the plants will appear as though some of the lower leaves had become rusty ; at the same time the leaves are sickly and atrophied. As the disease develops the number of rusty leaves increases ; the “ rust "" itself will be found on examination to consist of the spores of a fungus, known as the Puccinia graminis or corn mildew. The mycelium penetrates the tissues of the leaves, occupying the intercellular spaces, and thus gradually destroys them, with the effect of seriously injuring and reducing the corn crop. Shutt collected by hand on the same day in the same field samples of rust-free and rust-attacked wheat. The former have a normal ear both as to size and colour, and a plump, well-filled grain. The straw of the latter showed many spots of infection, while the ears were smaller than normal and the grains light and much shrivelled. The following are the results of analysis of the two samples of wheat : — E-ust-free. Eusted. Weight of 100 grains in grams . . 3-0504 1-49 Water per cent. . . 12-26 10-66 Crude Protein ,, . . 10-50 13-69 Crude Fat ,, . . 2-56 2-35 Carbohydrates ,, . . 70-55 68-03 Fibre ,, 2-29 3-03 Mineral Matter ,, 1-84 2-24 The protein is considerably higher in the rusted grain, a result probably due to the fact that protein is first lodged in the grain during the processes of metabolism, and afterward the carbohydrates. A result of rust attack is that the maturation of the grain is retarded, and the lodgment of starch is incomplete. But though the total protein is high, the wheat will probably be found to be lacking in strength [Jour. Amer. Chem. Soc., 1905, 366). 358. Smut. — ^This disease is also known as “ dust brand,” “ chimney sweeper,” and by other names all referring to the black appearance of ears of grain infested by it. When the grain is nearly ripe, there will be noticed here and there in a wheat field shrivelled looking ears, which look as though covered with soot. Smut is due to a fungus which has received the name of Ustilago segetum. The fungus develops within the seeds, destroying the contents of the grain, and replacing them by a mass of spores which appear as a fine brownish black powder. Smut is a very destructive parasite, and attacks barley, oats, and rye, and also, although to a some- what lesser extent, wheat. Viewed microscopically, the spores of U . 196 THE TECHNOLOGY OF BREAD-MAKING. segetuTU are found to be spherical, and to have a diameter of about 8 inkms. ^ their appearance is shown in the following figure. Fig. 20. — a. Smut, h, Buxt X 400 diameters. 359. Bunt or Stinking Rust.— Unlike smut, bunt produces no external signs of its presence in a wheat field : there is no sooty appearance o ® ear, nor any rust above the leaves. It is not until the wheat is ^ from the straw that the bunted grains are discovered in the sample. x er nally, these grains are plumper than those which are sound ; but on tnem being broken, the interior, instead of being white and fiour-bke is louna to be filled with a black powder, having a greasy feel when rubbed between the fingers, and a most foetid and unpleasant odour. This dust consists of the spores of a fungus termed Tilletea caries, mixed with portions ot its mycelium. The spores are much larger than those of smut, and, viewed under the miscroscope, appear as shown in Fig. 20 : they are about 17 mkms. in diameter. The presence of bunt is said not to affect the wholesomeness ot Hour ; it is stated that bunted flour is at times made up into gingerbread ; the other condiments used masking its colour and odour. With the extreme care manifested in modern systems of milling, it is improbable that bun often finds its way into the flour. 360. Ergot.— This disease is almost exclusively confined to rye ; like bunt and smut, ergot is due to a fungus which develops within the gram, filling its interior with a compact mass of mycelium and spores, and altering the starch cells by replacing the amylose with a peculiar oily matter, ihis fungus is termed Oidium ahortifaciens. The ergotised grams are violet- brown or black in colour, moderately brittle ; and when m quantity evolve a peculiar nauseous fishy odour, due to the presence of trimethylamme. Ergot possesses powerful medicinal effects, and when taken m anything over medicinal doses, acts as a violent poison. The presence of ergo m flour is tlierefore extremely dangerous. . . Chemical tests for the detection of ergot and moulds will be given in the analytic section of this work. Experimental* Work. 361. Prepare some malt wort; filter and allow the liquid to remain for some days in an open flask. In about 24 hours the liquid becomes BACTERIAL AND PUTREFACTIVE FERMENTATIONS. 197 turbid ; examine a drop under the microscope with the highest power at disposal. Bacteria will be seen in abundance ; notice that they have a distinct migratory movement. Examine a sample each day, and observe that the bacteria grow less active, and ultimately become motionless ; they have then assumed the zoogloea stage. Carefully search the liquid for other organisms ; bacilli should be detected, being recognised by their filamentous appearance. Vibrios should also be observed ; they appear very like bacilli, except that they have bent joints. When actively moving they exhibit an undulatory movement, depending on their rotation on their long axis. Examine microscopically some of the sediment of “ turned "" beer ; large quantities of bacilli can usually be observed. These organisms are also commonly found in bakers" patent yeasts. Place some fresh clear wort in a flask and plug the neck moderately tightly with cotton- wool ; boil the liquid for 5 minutes and allow to cool : notice that the contents of the flask remain clear. At the end of a week, remove the plug and examine a drop of the liquid under the microscope, bacteria and other organisms are absent. The wort is still sweet and free from putrefactive odour. Let the flask now stand freely open to the atmo- sphere : organic germs gain entrance, and putrefactive or other changes rapidly occur. On the next and succeeding days, examine microscopically. Procure a small quantity of milk and allow it to become sour ; examine microscopically for Bacterium lactis. Also, wash a few grains of malt in a very little water, and examine the washings for this organism. Prepare two samples of wort, strongly hop the one by adding hops in, the' proportion of one-tenth the malt used : boil the two samples, filter and set aside under precisely the same conditions. Observe the relative rate of growth and development of bacterial life in the two. CHAPTER XI. TECHNICAL RESEARCHES ON FERMENTATION. 362. — ^In this chapter are contained the results of certain technical researches made by the authors and others on matters having a more or less direct bearing on bread-fermentation. 363. Strength of Yeast. — ^To the baker, the first consideration about yeast is its strength or gas-yielding power : there are other effects which it also produces, but its all-round activity may be fairly measured by the quantity of gas it evolves from a suitable saccharine medium. The term “ strength is therefore used in this sense ; it follows that the strongest yeast will also raise bread better, because the rising of the dough is due to the gas evolved by the yeast from the saccharine constituents of the flour. Different modes have been adopted from time to time for the pur- pose of testing the strength of yeast. The essential principle of these has been to ferment a definite quantity of some saccharine fluid with a constant weight of yeast, at a constant temperature, and to then deter- mine the volume of gas evolved in a given time. Meissl, of Vienna, used the following process, which, like most others of its kind, is based on the principle that the strength of the yeast can be judged from the amount of carbon dioxide it produces from a certain quantity of sugar, the other substances being in equal proportions. In order to carry out the test, the following substances must be pre- pared by rubbing them together : 400 grams of refined cane-sugar, 25 grams of phosphate of ammonium, and 25 grams of phosphate of potassium. A small vessel should be ready at hand of 70 to 80 c.c. capacity, and fitted with an india-rubber stopper containing two holes, in one of which should be placed a bent glass tube, the long end of which should nearly reach the bottom of the vessel, and the top end, during the fermentation, should be corked up. The second hole serves for the reception of a small chloride of calcium tube. The testing of the yeast may then be commenced in the following manner : 4*5 grams of the above mixture should be stirred gently, and dissolved in 50 c.c. of distilled water. In this liquid one gram of the yeast on which the experiment is to be tried should be carefully stirred and mixed until no lumps are to be seen. The vessel with its contents must be weighed and then placed in water at a temperature of 30° C., and left to remain during six hours. At the end of this time it must be taken out and plunged immediately into cold water in order to cool it as quickly as possible. The stopper is then taken out of the bent glass tube, and the air allowed to enter during a minute or two, so as to drive out the carbon dioxide. Tlie vessel and its contents must then be weighed. The loss of ■weight arises from the quantity of carbon dioxide which has been thrown ofi during the process. By this method, the carbon dioxide is estimated by weight : the chloride of calcium tube is affixed for the purpose of retaining any traces of aqueous vapour which otherwise would escape. In many ways this apparatus and method were susceptible of improve- ment, at least when used for technical and commercial purposes. In the first place the actual weight of the flask with contents amounts to some 80 or 90 grams, while the weight of carbon dioxide evolved varied, in some experiments made by the author, from 0*291 to 1*237 grams. To 198 TECHNICAL RESEARCHES ON FERMENTATION. 199 accurately measure these differences of weight in an apparatus, itself weigh- ing so much, a very delicate balance is requisite. This method is capable, in competent hands, of yielding accurate results ; but it is tedious, and does not give all the information that could be wished. Another mode of procedure is to collect the gas in a jar over mercury in a pneumatic trough ; this undoubtedly gives the most accurate results, but is open to the objection that mercury is expensive, and the apparatus, from its great weight, heavy and cumbersome. The reader is already aware that water is capable of dissolving carbon dioxide gas to the ex- tent of its own volume ; this, therefore, is an obstacle to the employment of water for its collection. One of the authors, nevertheless, made the experi- ment, and found that on collecting the gas evolved by the yeast during fermentation, in the ordinary manner in a graduated gas jar over water, most interesting results could be obtained. These were of course not absolutely correct, because a certain quantity of the gas was absorbed by the water ; still, duplicate experiments gave corresponding quantities of gas, while most important information was gained as to the general char- acter of different yeasts when examined in this manner. Results obtained in this way may therefore be viewed as comparable with each other. 364. Yeast Testing Apparatus. — ^In the next place a series of experiments were made in which the gas was admitted to the graduated jar through the top, and so did not bubble through the water at all. When collected in this way the amount of absorption was small and very uniform. Two jars were two-thirds filled in this manner with washed carbon dioxide gas prepared from marble and hydrochloric acid. They were then allowed to stand, and the amount of absorption observed hourly. The rate of absorption, with the particular jars used, was as nearly as possible a cubic inch per hour. Subsequent trials with jars of one hundred cubic inch capacity gave an outside rate of absorption of two cubic inches per hour. A still better plan is to use instead of water an aqueous solution of cal- cium chloride of a degree of concentration giving a specific gravity of 1 *4. With this solution there is practically no absorption of carbon dioxide. A saturated solution of common salt (brine) may be used instead of the calcium chloride, with only slightly more absorption. As a result of numerous experiments, the authors employ one or other of the forms of apparatus figured below. 200 THE TECHNOLOGY OF BREAD-MAKING. The glass bottle, marked a in the figure, is of about 12 ounces capacity, and is fitted with india-rubber cork and leading tube, h. The sugar or other saccharine mixture to be fermented is raised to the desired tem- perature, and then placed in this bottle. The yeast is weighed out, and then also added ; they are then thoroughly mixed by gentle agitation. By means of an india-rubber tubing joint at c, the generating bottle is connected to the leading tube, e, of the glass jar, /. This leading tube is provided at d with a branch tube, which may be opened or closed by means of a stopper of glass rod and piece of india-rubber tubing. The jar, /, is graduated, as shown, into cubic centimetres commencing immediately below the shoulder with 0, and ending near the bottom with 1000. This constitutes the apparatus proper ; in use the generating bottle, a, is placed in a water-bath, g g. This bath is fixed on a tripod over a bunsen burner, and is provided with an iron grid, A, in order to prevent the generating bottle coming in absolute contact with the bottom of the bath. By means of an automatic regulator the bath is maintained at any desired temperature. The gas jar, /, stands in a pneumatic trough, i i. As a rule, more than one test is made at a time, the water-bath should therefore be sufficiently large to take four or six bottles at once : two pneumatic troughs are then employed, and either two or three of the gas jars, /, arranged in each. While for strictly accurate experiments it is essential that the yeast bottles be kept as nearly as possible at a definite temperature, yet results of interest may be obtained without the employ- ment of a water-bath. The whole apparatus should, under those circum- stances, be placed in some situation where, as nearly as possible, a constant temperature is maintained. At the start of the experiment the air is exhausted through d, which is again closed with the stopper. As the fermentation goes on the gas evolved is collected in /, and its volume read off, from the surface of the water, at the end of each half-hour or hour. Full and detailed particu- lars are given at the end of this chapter as to the exact mode of procedure in using this apparatus. When the requisite allowance is made for the absorption of the gas by water, the corrected reading very nearly corresponds with the absolute amount of gas which has been evolved. It is far better, however, to use brine and so prevent any absorption of the gas. There are slight varia- tions due to alterations of barometric pressure and of temperature ; these can, if wished, be calculated out and allowed for — that is not, however, for ordinary purposes necessary. Gases are usually measured at a stan- dard pressure of 760 millimetres, or very nearly 30 inches of mercury, that is with the barometer standing at 30. A rise or fall of the barometer through half an inch only makes a difference of one-sixtieth on the total reading, and this may as a rule be neglected. In case the estimation is being made in either the laboratory or a bakehouse, the temperature is, as a rule, fairly constant. Supposing it be taken at 70° F., then it will be found that a difference of 5° either way only causes a variation in the volume of the gas of one hundredth the total amount. Barometric and thermometric variations may, therefore, for most practical purposes, be neglected. Further, whatever variations there may be either in tem- perature or pressure, all the tests made at the same time are made under precisely similar conditions. In all the experiments quoted, except the later ones, the gas was col- lected over water. No corrections were, however, made for absorption, because it is evident that at the outset the carbon dioxide remains as a layer of gas within the bottle, simply displacing air over into / ; during this time no absorption can take place. It should, however, be remem- TECHNICAL RESEARCHES ON FERMENTATION. 201 bered that, when the gas remains stationary for any length of time, a quan- tity must have been evolved about equal to that being absorbed. In the alternative apparatus, the generating bottle, a, and leading tube, h, are the same as before. At c^, a glass stop-cock is fixed in the leading tube which is attached by means of india-rubber tubing to the further end of which just passes through an india rubber cork fixed in the glass bottle, e^, having a capacity of 600 c.c. or thereabouts. Another tube, /^, leads from the bottom of and has its lower end open. Under this is placed a graduated measuring jar, of 500 c.c. capacity. In use the yeast and fermenting medium are placed as before in the generating bottle, a. The bottle is filled with brine, and the apparatus fixed to- gether and arranged in position as shown in the figure. As gas is generated in the bottle, a, it displaces an equivalent amount of brine in the liquid passing over and being collected in the measuring jar, g^. Readings of the volume of brine thus displaced may be made hourly, and thus results obtained of a similar character to those with the other apparatus. When the collecting jar is filled to the 500 c.c. mark, the stop-cock, may be closed and the brine in g^ returns to e,^ and the collection and measurement of gas again commenced on reopening the stop-cock, c^. This second form of apparatus can be the more readily fixed up from appliances found in the laboratory, while both are practically identical in their working. In the first form, the gas within is under diminished pressure, any leakage there- fore will increase the apparent amount of gas evolved. In the second arrangement, the gas is under increased pressure, and consequently any leakage will result in loss of gas. 365. Degree oUAccuracy of Method. — ^This is a matter of great impor- tance, because unless fairly constant and accurate results are obtainable, little or no confidence can be placed in them, or any deductions based thereon. A number of duplicate experiments were therefore first made in order to test the accuracy of the estimations ; the results are appended. They serve also to show how the results may be entered up in the labora- tory note-book. For the composition of “ Yeast mixture ”, see paragraph 367 No. 1. Brewers’ Yeast, ^ oz. ; Yeast Mixture, J oz. ; Water, 6 oz. at 30° C. No. 2. Duplicate of No. 1. No. 3. French Compressed Yeas^-. J oz. ; Yeast Mixture, J oz. ; Water, 6 oz. at 30° C. No. 4. Duplicate of No. 3. 202 THE TECHNOLOGY OF BREAD-MAKING. Time. 0 J hour 1 „ IJ hours 2 2i 3 4 41 No. 1. No. 2. 0-0 0-7 6-5 14-2 i 22-0 30-0 ! 41-0 0-7 5-8 7-7 7-8 8-0 j 11-0 47*0 ! 54-5 G-0 ’•5 0-0 0-5 0-5 6-0 I ... 5-5 I- 74 13-8 8-2 22-0 29-7 I 74 41-0; 46-7 53-7 11-3 8-0 i Cubic Inches. 1 Temper;!- i ture. ! No. 3. No. 4. ! ' ’ 0*0 0*0. 2*5 : 29*7 ■ 3*1 ! i I i 3*1 2*5 15*2 17*7 1 30*0 16*1 , 19*2 30*0 ^ 21*8 21*4 41*0 39*1 29*8 21*0 20*7 62*0 59*8 ^ 28*9 20*0 20*4 82*0 80*2 29*5 ; 21*5 21*0 103*5 101*2 30*0 '-22*3 23*2 125*8 17*8 124*4 30*25 20*4 1 r 143*6 144*8 30*25 14*9 ' 15*9 158*5 9*5 160*7! 30*0 ! 9*3 ; 168*0 170*0 30*0 7*0 5*0 : 175*0 175*0 30*0 2*8 0*8 1 177*8' 1 175*8' : 29*9 j The figures placed opposite the brackets represent the volume of gas given off in each successive half-hour. A thermometer was placed in the water-bath and the temperature observed at the time of each read- ing, and registered in the last column. The temperature in this experi- ment shows considerably greater variations than that in those made later. It will be noticed that both pairs of du 2 :)licates agree very closely throughout the entire fermentation. It may here be mentioned that a half- ounce of sugar yields, on the supposition that the whole is transformed with carbon dioxide and alcohol, the following quantities : — I oz. of sugar =14*2 grams, and yields 7*30 grams of CO 2 = 3*705 litres = 226 cubic inches at 0° C. = 242 „ 20°C. (One cubic inch = 16*4 c.c.) It will be remembered that actually only about 95 per cent, of the sugar is thus converted into carbon dioxide and alcohol ; these quantities in strictness, therefore, require to be reduced about 5 per cent. As in the experiments to be now described the same brand or kind of yeast was used on different days, it was necessary, as a preliminary, to ascertain the degree of constancy of strength of the same yeast. Deter- minations were made on one brand of compressed yeast with the following results : — No. 1.— April 27, 1885, No. 2.— May 7, 1885, No. 3.— June 30, 1885, ) Yeast, I oz. ; Yeast Mixture, J oz. ; J Water, 6 oz. at 30° C. TECHNICAL RESEARCHES ON FERMENTATION. 203 Gas Evolved in Cijdic Inches. Time. No. 1. No. 2. No. 3. 1 0 0-0. 0-0, 0-0, 21-7 1 [24-5 1 [28-7 I liour. . 21-7 24-5 1 1 28-7| 41-3 1 '36-4 1 [31-9 2 hours 63-0 60-9 1 60-6 1 33-0 1 ^43-1 1 143-6 3 „ 96-0 104-0 1 1 104-2 1 1 34-3 1 '32-0 1 [40-8 4 „ 130-3 24-2 136-o| 1 [22-5 145-0 1 [30-0 5 „ 154-5 158-5| 1 175-0| 15-7 1 1 17-5 1 [ 2-8 6 ,, i 170-2' 175-0 1 1 177-8' 1 Although these results do not agree with that closeness observable in the duplicates, yet it will be seen that the yeast is throughout fairly simi- lar in behaviour ; still, it must be remembered that in experiments made on different days the results are not always strictly comparable, because the yeast is sure to be not absolutely the same in each case. 366. Effect of Different Media on Yeast Growth. — ^That certain substances are eminently fitted for aiding the gro^wth and development of yeast, while others are not so suited, has already been stated. In order to measure quantitatively the effect of sowing yeast in different solutions, the following determinations were made. 367. Comparison between Sugar, “ Yeast Mixture,” Pepsin, and Albumin. — The “ yeast mixture ” referred to is based on the fluid in which Pasteur cultivated a yeast, and which is known as “ Pasteur’s Fluid.” Pasteur employed a solution of sugar and ammonium tartrate to supply saccharine matter and nitrogen ; to this he added some yeast ash as a source of mineral constituents. This fluid may be closely imitated by use of the following formula — Potassium Phosphate . . . . , . . . . . 20 parts. Calcium Phosphate . . . . . . . . . . 2 ,, Magnesium Sulphate Ammonium Tartrate Purest Cane Sugar Water 2 100 1500 8376 10,000 parts. As this solution keeps badly, the yeast mixture consists of Pasteur’s Fluid, minus the Avater. The salts are first powdered and dried, and then mixed until thoroughly incorporated. This mixture has the great advantage that while dry it can be kept any length of time without change. Date, April 26, 1885. No. I. Pure sugar, J oz. (14*2 grams^) ; compressed yeast, J oz. (3*5 grams) ; water, 6 oz. (170 grams) at 30° C. ^ In these experiments an anomaly will be noticed in the systems of w'eights em- ployed. In deference to the fact that many of the readers of this book will be much more 204 THE TECHNOLOGY OF BREAD-MAKING No. 2. Yeast mixture, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. No. 3. Pure Sugar, J oz. ; pepsin, 1 *5 grams ; compressed yeast, J oz. ; water, 6 oz. at 30° C. No. 4. Yeast mixture, J oz. ; pepsin, 1*5 grams ; compressed yeast, J oz. ; water, 6 oz. at 30° C. At the expiration of seven liours, the following quantities of gas had been evolved : — No. 1 .. 51*3 cubic inches. i No. 3 .. 112*0 cubic inches. No. 2 .. 132*0 „ 1 No. 4 .. 181*5 Experiments were also made with pepsin and albumin by themselves, but neither of these gave practically any evolution of gas. From these experiments the following conclusions are derived : — Pure sugar undergoes a regular but somewhat slow fermentation. Sugar mixed with about ten per cent, of pepsin ferments at first more slowly, but afterwards much more rapidly. “ Yeast mixture,” consisting of sugar, ammonium tartrate, and inorganic salts, ferments from the commencement still more rapidly. Yeast mixture, with about 10 per cent, of pepsin, undergoes still more rapid fermentation. Nitrogenous bodies alone, as pepsin, albumin, in water, or 2J per cent, salt solution, evolve practically no gas. Pepsin and other nitrogenous bodies must therefore be considered, not as the substances from which yeast causes the evolution of gas, but as stimulating nitrogenous yeast foods. 368. Comparison between Filtered Flour Infusion, Wort, and Yeast Mix- ture Solution. — Pursuing the same line of investigation, experiments were next made for the purpose of examining and comparing flour infusion, wort, and yeast mixture, as fermentable substances. An infusion of flour w^as made by taking 400 grams of flour, and 1000 c.c. of water ; these were shaken thoroughly in a flask, from time to time, for half an hour, and then allowed to subside : the clear liquid was filtered, and its specific gravity taken ; this amounted to 1007 *2. Meantime, some malt wort had been prepared ; this was divided into two portions, the one of which was boiled, the other allowed to remain at the mashing heat. These were next cooled, and each diluted down until the specific gravity coincided with that of the flour infusion. A solution of yeast mixture of the same density was also prepared. Fermentation was started in each of these with the results given in the following table : — Date, May 8, 1885. No. 1. 40 per cent, filtered flour infusion, Sp. G. 1007*2, 6 oz. at 30° C. ; compressed yeast, J oz. No. 2. Unboiled malt wort, Sp. G. 1007*2, 6 oz. at 30° C. ; compressed yeast, J oz. No. 3. Boiled Avort, Sp. G. 1007*2, 6 oz. at 30° C. ; compressed yeast, i oz. familiar with the English than the metric weights and measures, the authors have, where practicable, used the former system. The relation between grams and fractions of an ounce may be understood by remem- bering once for all that 1 ounce or 16 drams = 28 '35 grams 1 „ „ 8 „ = 14-2 99 TECHNICAL RESEARCHES ON FERMENTATION. 205 No. 4. Yeast mixture and water, Sp. G. 1007*2, 6 oz. at 30° C. ; com- pressed yeast, oz. At tlie end of five hours, the following quantities of gas had been evolved : — • No. 1 . . 8*3 cubic inches. i No. 3 . . 18*2 cubic inches. No. 2 .. 17*1 „ 1 No. 4 .. 24*3 The flour mfusion evolved gas but slowly, and toward the end of five hours, over which the experiment lasted, had fallen off considerably. The two malt infusions yielded carbon dioxide at about double the speed ; that in the boiled wort being the higher. The greater quantity of gas in the latter instance is due to the fact that boiling coagulates some of the proteins of the wort, and so leaves a greater percentage of sugar in the liquid, when both are diluted to the same density. This is an interesting instance of the removal of proteins resulting in a more copious and rapid evolution of gas. The yeast mixture causes the carbon dioxide to be evolved with still greater rapidity. Summing up the results : — In solutions of the same density, Flour infusion, on fermentation, yields gas somewhat slowly ; Unboiled wort, at about double the speed ; Boiled wort, slightly more rapidly than the unboiled ; and Yeast mixture solution, at about three times the rate of the flour infusion. The soluble extract of flour is thereby shown to be capable of only a slow fermentation ; this is due to its containing a comparatively low proportion of sugar, and much of that of a kind which requires to be inverted before it can be fermented. 369. Comparison between Flour and its Various Constituents fermented separately. — From the baker’s point of view, it is of very great im_portance that he should know which of the several constituents of flour it is that affords, during fermentation, the gas by which his dough is distended. The following experiments were made for the purpose of obtaining definite information on this subject — No. I requires no further explanation. In No. 2, 34 grams of flour were mixed with 6 oz. (=170 c.c.) of water, being equivalent to 20 per cent, of flour in the water. In No. 3, the flour was agitated several times with large quantities of water, and allowed to sub- side between each washing, the supernatant liquid being poured off, and only the insoluble residue retained. In this manner, the washed insoluble residue is obtained comparatively free from the other constituents. Of these three samples. No. 2 represents the whole of the flour. No. I the soluble, and No. 3 the insoluble portion. No. 4 consisted of £0 per cent, flour infusion, with gelatinised starch added ; the whole being subjected to a temperature of 30° C. for 12 hours before fermentation : this method was adopted in order to determine what diastatic effect was produced by the flour infusion on the gelatinised starch, it being assumed that what- ever starch was converted into sugar would, under the influence of the yeast, be decomposed with the evolution of carbon dioxide gas. No. 5 was a somewhat similar experiment, made with gluten ; some flour was doughed, and then the gluten washed as weU as practicable in a stream of water. In order to get as large a surface as possible, this gluten was next rubbed in a mortar with clean sand ; it was in this way cut up into a ragged mass. The gluten was mixed with water and kept at 30° C. for 12 hours, in order to permit any degrading action, that warm water is capable of exerting on gluten during that time, to assert itself. In Nos. 4 and 5, yeast was added at the end of 12 hours. No. 6 was a repetition of No. 4, except that the gelatinised starch and flour infusion were mixed immediately before fermentation. In No. 7 the starch was simply added 206 THE TECHNOLOGY OF BREAD-MAKING. to the flour infusion without previous gelatinisation. No. 8 consisted of wheat-starch and water only, to which yeast was added. The starch used for these experiments was specially prepared in the laboratory from the best Hungarian flour by washing the dough, enclosed in muslin, thus separating the gluten. The starch was allowed to settle, and the super- natant liquid poured ofl ; the starch was then stirred up with some more water, and again allowed to subside. These washings were repeated daily for about a fortnight, at the end of which time the starch was air- dried. On being tested with Fehling’s solution the starch gave no trace of preci- pitate : its purity was therefore assured. This series of fermentation tests altogether extended over a period of three days. Date, May 11, 1885. No. 1. 20 per cent. Altered infusion of flour, 6 oz. at 30° C., compressed yeast, J oz. No. 2. 34 grams flour ; water, 6 oz. at 30° C. ; compressed yeast, J oz. No. 3. Washed insoluble residue from 34 grams of flour : water, 6 oz. at 30° C. ; compressed yeast, J oz. Date, May 12, 1885. No. 4. 20 per cent, filtered flour infusion, 6 oz. at 30° C. ; wheat starch, 5 grams taken and gelatinised, cooled, then added to flour infusion. Mixture placed in bottle and maintained at 30° 0. for 12 hours ; then J oz. compressed yeast added and fer- mentation commenced. No. 5. Moist thoroughly washed gluten, 5 grams, triturated in mortar with sand in order to expose large surface : gluten with 6 oz. of water at 30° C. placed in bottle and maintained at 30° C. for 12 hours ; then ^ oz. compressed yeast added and fer- mentation commenced. Date, May 13, 1885. No. 6. 20 per cent, filtered flour infusion, 6 oz. at 30° C. ; wheat starch, 5 grams, gelatinised ; compressed yeast, J oz. No. 7. 20 per cent, filtered flour infusion, 6 oz. at 30° C. ; wheat starch, 5 grams, ungelatinised ; compressed yeast, J oz. Date, May 11, 1885. No. 8. Wheat starch, 5 grams, gelatinised, water 6 oz. at 30° C. ; com- pressed yeast, J oz. At the expiration of six hours, the following quantities of gas had been evolved No. 1 2*5 cubic inches. No. 5 . . 1*3 cubic inches. No. 2 .. 17-5 No. 6 . . 33-7 No. 3 . . 3-0 No. 7 .. 8-2 No. 4 .. 37-5 No. 8 .. 0-9 y No. 1, consisting of 20 i)er cent, flour infusion, gave ofl very little gas. the quantity amounting to only 2*5 cubic inches in six hours ; this is very much less than that obtained in the previous series of experiments in which a 40 per cent, infusion was employed ; the latter gave ofl 8*3 cubic inches in five hours. No. 2, containing the whole of the flour, gave ofl gas much more copiously, in six hours there being 17*5 cubic inches of gas evolved. After the second hour, the evolution fell ofl slowly but regularly.^ The washed residue gave ofl just the same amount of gas as did the filtered infusion ; in fact, at the end of the fifth hour. No. 3 gave the higher reading. ^ In all these tests, readings were made either every hour or half-hour, but usually the result of one reading only is here given. When of special interest, howev^er, the explanatory remarks contain also references to other readings. TECHNICAL RESEARCHES ON FERMENTATION. 207 It will be noticed that the whole of the flour gives off three times as much gas as do the filtered infusion and the washed residue together. The reason is that, when flour is shaken with water and then filtered, tlie substances which under the action of yeast evolve gas are not all removed in the fil- trate : they are only separated from the insoluble residue with great diffi- culty, and several washings do not so thoroughly remove fermentable matter as to leave the residue completely unfermentable. That the fer- mentation in No. 3 is not due to the insoluble residue is proved by the result of experiment No. 5 ; for with well washed and kneaded gluten, but very little gas is evolved, the total amount in nine hours being only 1*5 cubic inches, and this although the gluten for twelve hours previous to fermen- tation was digested with water at 30° C. Much of the fermentable matter •of flour belongs to what may be called the semi-soluble portion, that is, the part of the flour which is retained by an ordinary filter paper, but on kneading is readily separated by the mechanical action from the gluten. In Nos. 4 and 6 the quantities used are the same, but the former of the two samples affords evidence of diastasis having been occasioned during the twelve hours for which the gelatinised starch was subjected to the action of the flour infusion. No. 6 at first proceeded somewhat the more rapidly, but evolved very little gas during the second hour ; during the third hour, however, it recovered itself and proceeded regularly, until at the expiration of six hours the evolution of gas ceased, with a total of 33*7 inches. In No. 4 the fermentation proceeds rapidly and regularly, falling off towards the end, and finishing at five hours with 37 *5 cubic inches. As a result of the previous diastasis, a larger quantity of gas is evolved, but in each instance the greater part of the starch remained behind, as if 5 grams of starch were completely changed into sugar, and then by fer- mentation into carbon dioxide and alcohol, the yield of gas would roughly be about 85 cubic inches at 20° C. The diastatic action of the flour infusion will have more or less effected the hydrolysis of the starch into dextrin and maltose ; the latter will have undergone fermentation, while the former is unfermentable. Experiment No. 8 shows that the diastasis of the starch is effected by the flour infusion, and not by the yeast, for where pure gela- tinised starch and yeast alone are employed, exceedingly little gas is evolved ; during eight hours, but 1*2 cubic inches only having accumulated. This experiment was allowed to proceed overnight, and at the end of twenty- one hours, 7*0 cubic inches had been evolved. Another reading \va.s taken at the end of the twenty-second hour, and showed that 0*8 cubic inches had been evolved during the hour. It would seem that the diastatic action of yeast on pure starch increases somewhat after some hours ; but within a limit of eight hours, which covers the time that flour is in most instances subjected to fermentation, little or no action has occurred. The greater evolution of gas after twenty-one hours may possibly be due to sugar formed by the action of bacteria on the starch. Very striking in connection with this is the result obtained in experiment No. 7 for when the ungelatinised starch was mixed with flour infusion and subjected to fermentation, 8*5 cubic inches of gas were obtained in eight hours. The flour infusion must under these circumstances have succeeded in hydrolysing some of the starch ; for although starch is washed most carefully, there will always be a certain number of cells whose walls are sufficiently thin to permit diastasis to occur ; and as stated in a previous chapter, some investigators are of opinion that even unbroken wheat starch cells are comparatively readily attacked by hydrolysing agents. (Refer to Chapter VIII., para- graph 257). Summing up the results obtained in these experiments, it is found that — Filtered flour infusion supports fermentation slowly. 208 THE TECHNOLOGY OF BREAD-MAKING. The frequently washed residue of flour supports fermentation at alout the same rate. The entire flour, mixed with water, evolves about six times as much gas as either the Altered infusion or the washed residue from the same weight. Kneaded and washed gluten evolves practically no gas. Flour infusion and gelatinised starch together evolve gas in considerable quantity. The quantity of gas is increased when the infusion and the gelatinised starch remain together some time before fermentation ; which result is due to diastasis- by the proteins of the infusion. Ungelatinised starch, under the influence of yeast and flour infusion, evolves- a moderately large quantity of gas. Gelatinised starch alone undergoes little or no fermentation during a period of eight hours, but ferments slowly after standing some twenty hours. 370. Further Investigation of Fermentation of Flour Infusion. — ^In order to further determine the source of gas during the fermentation of flour infu- sion, the following experiments were made : — A forty per cent, filtered infusion of stone milled flour, from English wheat, was prepared by taking 600 grams of flour, and 1500 c.c. of distilled water : these were several times shaken together during half an hour, and then allowed to subside. The upper layer of liquid was next poured off and filtered through washed calico : this was subsequently again filtered in the ordinary manner through paper until perfectly clear. On testing with iodine no colour was pro- duced, thus showing the absence of both starch and amyloins. The specific gravity of the infusion v^as 1008*5, being somewhat higher than that of the forty per cent, infusion used in a previous experiment. A portion of the infusion was tested for sugar, before and after inversion, and also for pro- teins. Six ounces of the infusion were then fermented at 25° C., with a quarter-ounce of compressed yeast. The experiment was continued for twenty-two hours, at the end of which time fermentation had entirely ceased. The clear liquid was then decanted off from the layer of yeast at the bottom, and tested for sugar and proteins as was done in the separate portion of the original infusion. To the yeast remaining in the bottle there was at once added a half-ounce of sugar and six ounces of water at 25° C., and the testing apparatus set up, and the quantity of gas evolved measured. The sugar was estimated by Fehling’s process in the following rnan- i^er : — A weighed quantity of the flour infusion was raised to the boiling ])oint, and maintained at that temperature for about five minutes, in order to coagulate proteins ; the loss by evaporation was then made up by the addition of distilled water, and the solution filtered. Quantities taken = 25 c.c. Fehling's Solution. 50 c.c. Water. 20 c.c. Forty per cent. Flour Infusion. IV eight of cuprous oxide, CuaO, yielded = 0*1531 grams. Assuming tliis ])recipitate to be due to maltose, then 0*1531 X 0*7758 = 0*1187 grams of maltose in 20 c.c. of the flour infusion = 1*48 per cent, of maltose in the flour. In the next place, 50 c.c. of the flour infusion were taken, 5 c.c. of fuming hydrochloric acid added, and the solution inverted by being raised to 68 C. Tlie acid was tlien neutralised by solid sodium carbonate, and the solution made up to 100 c.c. with water. This produced a twenty per cent, inverted solution. Quantities taken = 25 c.c. Fehling^s Solution. 50 c.c. Water. 20 c.c. Twenty per cent, inverted Flour Infusion, j TECHNICAL RESEARCHES ON FERMENTATION. 209 Weight of cuprous oxide, CU 2 O, yielded = 0*1860 grams. In 20 c.c. of a forty per cent, solution there would be double this quan- tity = 0*1860 X 2 = 0*3720 grams. From this must be deducted the amount of precipitate due to the maltose present. 0*3720 — 0*1531 = 0*2189 grams of CU 2 O due to a reducing sugar pro- duced by inversion. Assuming this sugar to be cane-sugar, or at least to have the same reducing power, then 0*2189 X 0*4791 = 0*1048 grams of cane-sugar in 20 c.c. of the forty per cent, infusion = 1*31 per cent, of cane-sugar in the flour. [^The total sugar in the flour would thus be 2*79 per cent. After fermentation, the upper liquid from the yeast bottle was also tested for sugars, after filtration and coagulation of proteins as before. The uninverted solution gave no precipitate whatever with Fehling’s solu- tion. A portion was next inverted with acid in the manner already des- cribed ; 20 c.c. of this solution gave a slight trace of precipitate with Fehling's solution, which was too little to weigh. So far, the practical result may be summed up in the statement that filtered aqueous flour infusion contains two or more varieties of sugar ; these during the act of fermentation entirely dis- appear. The infusion was tested for proteins by distillation with alkaline per- mcinganate solution, with the following results, calculated to the percentage present in the flour — In the infusion before fermentation — 0*76 per cent. ,, ,, after ,, 0*78 ,, Compared with analyses of other flours, these quantities are low ; this is probably accounted for by a forty per cent, infusion being made, whereas a ten per cent, infusion is used in most analyses ; the more dilute solution extracts the somewhat viscous proteins with greater readiness. The only deduction from these determinations is, that the amount of proteins in a filtered flour infusion is practically unchanged by the act of fermentation, there being no disappearance whatever of these bodies. The following are the results of the fermentation experiments — No. 1. Flour Infusion, 6 oz. ; compressed Yeast, J oz. ; Temperature, 25° C. No. 2. Yeast from previous experiment after cessation of fermenta- tion : Sugar, J oz. ; Water, 6 oz., at 25° C. At the expiration of six hours, the following quantities of gas had been evolved : — No 1 . . 9’6 cubic inches. | No 2 . . 73‘5 cubic inches. As six ounces of the forty per cent, flour infusion would contain the soluble matter of 68 grams of flour, it follows that there would be present, according to the analysis, 1*89 grams of sugar. This quantity, if entirely converted during fermentation into carbon dioxide and alcohol, would yield about 32 cubic inches of gas at 20° C. By the method adopted for testing, 15 cubic inches were registered at the end of twenty- two hours ; to this would have to be added a correction for the amount lost by absorp- tion by the water, in order to obtain a correct estimate. It is difficult, when the total quantity of gas evolved is small, to determine with accuracy the loss by absorption, because the gas in the apparatus consists of a mix- ture in which air is predominant, consequently the rate of absorption is less than with pure carbon dioxide gas. If it were desired to accurately estimate the quantity of gas, collection over mercury would have to be adopted. This is of little importance in the present experiment, because the total measured comes well within the amount of gas that the sugar would theoretically yield. In other words, there is no need to go outside the sugar to find a source from which the carbon dioxide is obtained, as the p 210 THE TECHNOLOGY OF BREAD-MAKING. whole of the sugar disappears, and in the act of fermentation is capable of yielding more gas than that observed to be evolved. That the cessation of fermentation is not due to the exhaustion of the yeast is proved by experi- ment No. 2, in which the same yeast has more sugar added to it, when a vigorous fermentation was immediately set up. That the cessation of fermentation is due to the exhaustion of the sugar is proved by that com- pound being absent on analysis of the infusion after fermentation. Summing up the whole of the results — Flour Infusion. Before Fermentation. Sugar, 1*89 grams in the six ounces of infusion. Proteins, 0*517 grams present. j After Fermentation. Sugar, absent. Proteins, 0*530 grams present. When Fermentation had ceased, 15 cubic inches of gas had been evolved, and the yeast was still unexhausted, and capable of in- I ducing fermentation in fresh sugar j solution. , Reasoning on these results, together with those obtained in the series of experiments on flour and its various constituents taken separately, the only logical conclusion is that the fermentation of dough is essentially a saccharine fermentation. It may be demurred that the circumstances are different as an aqueous infusion to those which hold in a tough elastic mass such as dough. But it is inconceivable that the fermentation actually immediately depends on the conversion of any but soluble constituents of the flour into gas ; therefore, if those proteins, so soluble as to pass through filter paper, are not capable of yielding gas as a result of fermentation by yeast, it follows that the more insoluble protein compounds likewise will not yield gas. The fact that washed gluten yields no gas affords corroborative proof of this point. (The small quantity actually obtained by experiment may be accounted for by the well-known difficulty of perfectly freeing gluten from all starchy and soluble matters). That the fermentation of the flour itself yields several times more gas than does the Altered infusion, lends no support to the theory that it is the protein matter that is evolving gas, because it has been shown that pure ungelatinised starch causes a marked evolution of gas, being doubtless first converted into dextrin and maltose by diastasis. The fermentability of the washed residue is also accounted for by its containing starch. Supposing even that in dough, after fer- mentation had ceased, sugar as such existed and could be removed and detected by analytic methods, that of itself would be no proof of the evolu- tion of gas being at the expense of the proteins, or peptones derived there- from (for the argument equally applies to these latter bodies), because simultaneously with the fermentation produced by the yeast there is a pro- duction of sugar by diastasis of the starch. Fermentation of sugar in a stiff dough is rough work for yeast cells, and it may well be that after a few hours they are thoroughly exhausted, and disappear through disrupt- ion of their cell walls : the continuance of diastasis would still cause the slow production of more or less sugar. Further, the diastasis of the starch must throughout fermentation precede its subsequent conversion into car})on dioxide and alcohol ; and so, if the reaction be stopped at any point, more or less sugar would as a rule be found. Again drawing a con- II 'ECHNICAL RESEARCHES ON FERMENTATION. . 211 elusion, the fermentation of dough is in part due to the fermentation of the sugar present, in part to the diastasis of a portion of the starch of the flour and its subse- quent fermentation ; these sources are sufficient, and more than sufficient, for the production of all the gas evolved ; these statements admit of experimntal proof. There is no satisfactory evidence in favour of the gas evolved being in any sensible degree derived from the protein constituents of dough. It should be noticed that no assertion is made that no gas whatever is derived from the protein constituents of flour ; it is possible that in extreme cases gas is produced from protein matters as a result of butyric and putrefactive fermentations ; but in ordinary bread-making, as it holds in the United Kingdom, the amount of gas derived from this source is of no importance compared with that from sugar, and indirectly from starch. Whatever amount of gas there is that is thus obtained from proteins is the result, not of the action of yeast, but of bacteria. Further, the statement that protein bodies do not themselves evolve gas during panary fermentation must not be construed into meaning that they do not affect the quantity evolved. In their capacity as nitrogenous yeast foods, they aid the yeast in its development, and consequently in its production of gas by decomposition of saccharine bodies. 371. Effect of Salt on the Fermentation of Flour. — Most bakers are familiar with the general statement that salt retards fermentation : in order to determine the amount of such retardation the following experi- ments were made. In the first, flour and water alone were fermented ; the others consisted of flour mixed with salt solutions of various strengths. The appended table contains the results : — • Date, May 27, 1885. No. 1. Flour, 34 grams ; water, 6 oz. at 30° C. ; compressed yeast, J oz. No. 2. Flour, 34 grams ; water, 6 oz. at 30° C. ; compressed yeast, J oz. ; salt, 2*5 grams = 1*4 per cent, salt solution. No. 3. Flour, 34 grams ; water, 6 oz. at 30° C. ; compressed yeast, J oz. ; salt, 5*0 grams = 2*9 per cent, salt solution. No. 4. Flour, 34 grams ; water, 6 oz. at 30° C. ; compressed yeast, J oz. ; salt, 8*5 grams = 5*0 per cent, salt solution. At the termination of six hours, the following quantities of gas had been evolved : — No. 1 . . 18*2 cubic inches. | No. 3 . . 15*1 cubic inches. No. 2 . . 15*2 „ I No. 4 . . 13-3 In the first test, 19*2 cubic inches of gas were evolved in seven hours, while with 1*4 per cent, of salt present in the solution (No. 2) the gas was diminished to 15*8 cubic inches. Summing up the conclusions derived from this series of experiments — The use of a 1*4 per cent, solution of salt instead of water produced a marked diminution in the evolution of gas. Increasing the amount of salt to 2*9 per cent, made very little difference on the speed of fermentation. With 5*0 per cent, of salt, gas was evolved still more slowly. 372. Effect on Fermentation of addition of Various Substances to Yeast Mixture. — Taking yeast mixture as being a substance well fitted to undergo fermentation, the following experiments were made in order to determine the effect of the addition of certain other substances which have an impor- tant bearing on the fermentation operations involved in bread-making. The appended table describes sufficiently the substances used in each test of the series ; the quantity of yeast mixture was constant throughout. 212 THE TECHNOLOGY OF BREAD-MAKING. Date, May 19, 1885. No. 1. Yeast mixture, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. Date, May 12, 1885. No. 2. Yeast mixture, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; pure wheat starch, 5 grams. No. 3. Yeast mixture, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; wheat starch, 5 grams, gelatinised and allowed to cool. Date, May 14, 1885. No. 4. Yeast mixture, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; raw flour, 5 grams. Date, May 13, 1885. No. 5. Yeast mixture, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; flour, 5 grams, gelatinised with small quantity of water, and allowed to cool. No. 6. Yeast mixture, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; potato, 5 grams, boiled. Date, May 18, 1885. No. 7. Yeast mixture, J oz. ; compressed yeast, J oz. ; potato, 5 grams, in small pieces, boiled ; clear filtered water employed for boiling them, made up to 6 oz. at 30° C., and used instead of ordinary water. No. 8. Yeast mixture, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; salt, 5 grams = 2*9 per cent, salt solution. Date, May 19, 1885. No. 9. Yeast mixture, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; salt, 2*5 grams = 1*4 per cent, salt solution. No. 10. Yeast mixture, ^ oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; salt, 8*5 grams = 5 per cent, salt solution. In six hours, the following quantities of gas had been evolved : — No. I . . 174*5 cubic inches. No. 6 . . 188*0 cubic inches. No. 2 . . 173*7 No. 7 . . 183*5 No. 3 . . 167*8 No. 8 .. 170*2 No. 4 .. 173*5 No. 9 .. 1780 No. 5 .. 205*2 No. 10 .. 150*5 The results of No. 2 are identical with those of No. 1, showing that the starch under these circumstances is unacted on. This experiment stands out in contrast to that in a previous series (paragraph 369) in which un- gelatinised starch was added to flour infusion. There, a diastatic agent was present, and diastasis of the starch ensued ; here, with yeast only, the starch remains throughout unaltered. In No. 3 the starch was gela- I tinised and allowed to cool ; in this case there is a marked diminution j in the evolution of gas : this is most likely due to the viscous nature of the liquid containing starch in solution, the effect being a mechanical one, resulting from a physical retardation of fermentation. During the latter part of the experiment, which altogether extended to ten hours, the pro- duction of gas exceeds that in No. 1, amounting to 183*5 against 174*5 cubic inches, and does not terminate until the end of the ten hours, whereas | both Nos. 1 and 2 ceased within six hours. In No. 4 raw flour is substituted j for ungelatinised starch : again a series of readings are obtained closely |i resembling Nos. 1 and 2, and showing that with yeast mixture as a basis, I raw flour produces no appreciable action. But when the flour is gelatinised i TECHNICAL RESEARCHES ON FERMENTATION 213 as in No. 5, the evolution of gas is more copious and more rapid, and at the end of eight hours a total of 209*4 cubic inches of gas is registered, with an increase during the last hour of 1*2 cubic inches. Gelatinised flour favours fermentation to a much greater extent than does gelatinised starch ; the principal chemical difference between the two is that in the former there are present the proteins of the flour non-coagulable by heat. To No. 6 were added 5 grams of potato, boiled ; the result is a considerable increase in the amount of gas evolved, which shows itseK more particularly during the earlier period of fermentation : boiled potato therefore acts as a stimulant, and also furnishes saccharine matter as food for the yeast. In experiment No. 7, it is remarkable, and contrary to the generally received ideas, to find that the clear filtered water in which potatoes were simply boiled exercises such marked influence on fermentation. The increase in rapidity of production of gas is very nearly as great as when the whole of the potatoes are used. In No. 7, 9 more cubic inches of gas were evolved than in No. 1, the action terminating at the same time. It may be of interest to mention here that in some parts of Lancashire, where it is a prevalent custom for families to make their own bread, they adopt the plan of setting the sponge with water in which the potatoes have been boiled. Nos. 8, 9, and 10, were similar experiments to those of the pre- ceding series (paragraph 371), except that the action of salt was tested on yeast mixture instead of on flour. No. 8 shows a slightly less quantity of gas evolved than does No. 1. No. 9, on the other hand, shows a decided increase in the quantity of gas over that evolved either in Nos. 1 or 8. In No. 10, however, where 5 per cent, of salt is employed, the gas falls off to 165*2 cubic inches in seven hours, although at the end of the time fermenta- tion is still actively proceeding. Summarising the results of these experi- ments. The addition to yeast mixture of — Ungelatinised wheat-starch has no practical effect on fermentation. Gelatinised wheat-starch at first retards the action, which afterward is slightly accelerated. Raw flour produces very little action. Gelatinised flour induces a much more rapid and copious evolution of gas. Boiled potato produces a similar effect to gelatinised flour, but to a less extent. The water used for boiling potatoes is almost as effective as the potatoes themselves. Quantities of salt, up to 3 per cent, of water used, do not retard fermen- tation greatly : above that quantity salt considerably diminishes the evolution of gas. 373. Effect on the Fermentation of Sugar of the addition of Flour and Potatoes. — ^As yeast mixture contains within itself not only sugar, but also other ingredients which stimulate a rapid fermentation, it was thought advisable to repeat some of the preceding experiments with sugar only. Accordingly, the experiments reeorded in the following table were per- formed. Date, May 21, 1885. No. 1. Sugar, ^ oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; raw flour, 5 grams. No. 2. Sugar, J oz. ; eompressed yeast, J oz. ; water, 6 oz. at 30° C. ; flour, 5 grams, gelatinised in small quantity of water and allowed to cool. Date, May 18, 1885. No. 3. Sugar, J oz. ; compressed yeast, J oz. ; water, 6 oz. at 30° C. ; potato, 5 grams, boiled. 214 THE TECHNOLOGY OF BREAD-MAKING. No. 4. Sugar, J oz. ; compressed yeast, J oz. ; potato, 5 grams, in small pieces, boiled ; clear filtered water employed for boiling them, made up to 6 oz. at 30° C., and used instead of ordinary water. Quantities of gas evolved in six hours : — No. 1 . . 84*3 cubic inches. No. 3 . . 138*1 cubic inches. No. 2 .. 135-0 „ ' No. 4 .. 133*6 In the first experiment, with raw flour, the quantity of gas evolved keeps very close to that evolved from the sugar solution and yeast only, until three hours have elapsed. After that time the speed of evolution of gas falls off sharply, until in nine hours the quantity of gas evolved is only just as much as the sugar alone had evolved in six hours. The actual diminution of speed of the evolution of gas, as a result of the pre- sence of flour, is noticeable in several experiments. With gelatinised flour, on the other hand, the fermentation proceeds more rapidly, and to a greater extent than with sugar only. The speed of production of gas is less than in the corresponding experiment of the previous series with yeast mixture, but as the action continues longer before commencing to fall off, the actual amount of gas evolved is about the same. The result of No. 3 with boiled potato is almost similar to No. 2. No. 4, containing boiled potato water, ferments at almost exactly the same rate as did No. 2 with the whole of the potato. Summing up. The addition to sugar of — Raw flour retarded the fermentation in the latter part of the experiment. Gelatinised flour, boiled potato, and boiled potato water, each stimulated and increased the amount of fermentation to about the same degree. 374. Effect of Temperature on Fermentation. — In order to measure quantitatively the effect of variations of temperature on the produetion of gas by fermentation, the following experiments were made : — Tw^o different brands of compressed yeast were employed, one of which is desig- nated yeast “A,” the other yeast “ B ; the same quantity of yeast was employed throughout the experiment. The series included tests by each yeast on sugar, yeast mixture, and flour, at the respective temperatures of 20°, 25°, 30°, and 35° C. = (68°, 77°, 86°, and 95° F.). The following are the results of one set of tests : — Date, July 3, 1885. — The complete series at 20° C. made this day. „ July 2, 1885.— „ „ 25° C. „ June 30, 1885.— „ „ 30° C. „ June 29, 1885.— „ „ 35° C. No. 1. Yeast mixture, J oz. ; compressed yeast. A, J oz. ; water, 6 oz. at 20° C. No. 2. Yeast mixture, J oz. ; compressed yeast. A, J oz. ; water, 6 oz. at 25° C. No. 3. Yeast mixture, J oz. ; compressed yeast. A, J oz. ; water, 6 oz. at 30° C. No. 4. Yeast mixture, 4 oz. ; compressed yeast. A, J oz. ; water, 6 oz. at 35° C. Gas evolved at the end of six hours : — No. 1 . . 83*8 cubic inches. 1 No. 3 . . 177*8 cubic inches. No. 2 .. 113*3 „ I No. 4 .. 175-0 (At the end of three hours. Nos. 3 and 4 had evolved 104*2 and 128*0 cubic inches respectively). Considering first the series consisting of yeast A with yeast mixture, a temperature of 25° C. increases the total quantity of gas considerably TECHNICAL RESEARCHES ON FERMENTATION. 215 over~tliat evolved at 20° C. ; a further increase to 30° more than doubles the average speed of evolution of gas. Beyond 30° the amount of gas evolved is not materially increased with the rise in temperature, thus at 35° C. there is very little more gas evolved than at 30° C. In the series where sugar is substituted for yeast mixture, the production of gas is less, but the same general relation exists between the various members of the series. With flour, on the other hand, there is a more equal increase, as shown by the following table, still there is a greater increase between Nos. 2 and 3 than the others : — No. 1. Flour, 34 grams ; compressed yeast. A, J oz. ; water, 6 oz. at 20° C. No. 2. Flour, 34 grams ; compressed yeast. A, J oz. ; water, 6 oz. at 25° C. No. 3. Flour, 34 grams ; compressed yeast, A, J oz. ; water, 6 oz. at 30° C. No. 4. Flour, 34 grams ; compressed yeast. A, J oz. ; water, 6 oz. at 35° C. Gas evolved at the end of six hours : — No. 1 . . 14*6 cubic inches. No. 2 . . 18'-2 No. 3 . . 24*4 cubic inches. No. 4 .. 28-3 Another precisely similar series of experiments were made with B yeast, which, being the stronger yeast of the two, gave off in every case more gas than did yeast A in the corresponding experiment. This differ- ence was not so striking when yeast mixture was used, because its stimu- lating effect helped the weak yeast proportionally the more. But in sugar each yeast has to depend more fully on its own vitality in producing fer- mentation. Consequently the stronger yeast B causes the evolution of a proportionately higher quantity of gas than does the yeast A. Summarising the results obtained — In the three media employed, the rapidity of production of gas increases with the temperature ; this increase is more marked between 25° and 30° than between 30° and 35° C. 375. Behaviour of Yeasts at High Temperatures. — ^In view of the fact that, in baking, some of the work of the yeast is done in the oven, it be- comes of interest to ascertain how different yeasts behave as fermenting agents at high temperatures. For this purpose the following experiments were made in 1895 : — Experiment on Yeast at 77° F. (25° C.) Quantities taken — yeast, J oz ; flour, 2*4 oz. ; water, 6 oz. No. 1. — Compressed distillers’ yeast. ,, 2. — Compressed brewers’ yeast, ordinary. ,, 3. — ,, ,, ,, special. „ 4. — Thin brewers’ yeast. Gas Evolved in Cubic Inches. Time. No. 1. No. 2. No. 3. No. 4. 1 hour 4-0 2-0 7-0 2 hours . . — 6-0 15-0 — 3 15-0 10-0 18-5 4-0 4 — 13-0 22-5 6-5 5 — — — 8-0 5J ,, 21-0 — — — 7 22-0 — l 216 THE TECHNOLOGY OF BREAD-MAKING. Yeasts Nos. 1 and 4 were next tested in precisely the same manner, except that the temperature was raised to 122° F. (50° C.) The following were the results : — Gas Evolved in Cubic Inches. Time. No. 1. No. 4. 1 hour 13-0 1-0 2 hours . . ■ . . 22-75 — 2i „ 23-15 — 3 „ Stop 1-5 Notice how completely No. 4 ceases work at this higher temperature ; while No. 1 for a time is even more energetic in action. In the next place a series of tests were made at 131° F. (55° C.). The quantities taken were not precisely the same as in the previous tests, but are given in detail. No. 1. Compressed distillers’ yeast, J oz. ; flour, 1*2 oz. ; water, 6 oz. No. la. Yeast as No. 1 ; sugar, J oz. ; water, 6 oz. [No. 4. Thin brewers’ yeast did not work with flour at 122° F.] No. 4a. Thin brewers’ yeast, J oz. ; sugar, J oz. ; water, 6 oz. No. 5. Another sample compressed distillers’ yeast, J oz. ; flour, * 1*2 oz. ; water, 6 oz. No. 5a. Yeast as No. 5 ; sugar, J oz. ; water, 6 oz. Gas Evolved in Cubic Inches. Time. No. 1. No. la. No. 4a. No. 5. No. 5a. 15 minutes 1-0 1-25 2-0 2-0 30 4-0 5-0 — 2-75 3-0 1 hour . . 6-25 7-75 2-75 3-0 3-5 2 hours . . 6-5 8-75 4-0 3-5 5-5 3 „ 7-0 10-0 5-75 — — 4 Stop 10-75 Stop 4-0 7*5 Comparing the two samples of distillers’ yeast ; No. I, it will be noticed, works more vigorously, both in flour and in sugar, than No. 5. The thin brewers’ yeast. No. 4, works at this temperature in sugar ; although inactive in flour and water, at a temperature lower by nine degrees. At a tem- perature of 140° F., neither Nos. 1 nor 4 evolved any gas in a sugar solution. These results agree broadly with the general behaviour of the yeasts during baking. They were first published by one of the authors in The Science and Art of Bread-making, 1895, and establish the fact that at high temperatures, distillers’ yeast retains its activity to a much higher point^than does English brewers’ yeast. 370. Comparative Fermentative Tests with Brewers’ and Distillers^ Yeasts in Flour and Sugar Solutions. — ^The following experiments were made with the view of comparing the fermentative capacity of brewers’ and distillers’ yeasts in flour and sugar solutions respectively : — Date, October 22, 1885. No. 1. Yeast mixture, J oz. ; water, 6 oz. at 25° C. ; French com- pressed yeast, J oz. TECHNICAL RESEARCHES ON FERMENTATION. 217 No. 2. Sugar, J oz. ; water, 6 oz. at 25° C. ; French compressed yeast, i oz. No. 3. Flour, 68 grams ; water, 6 oz. at 25° C. ; French compressed yeast, J oz. f- No. 4. Yeast mixture, J oz. ; water, 6 oz. at 25° C. ; compressed Eng- lish brewers' yeast, J oz. No. 5. Sugar, J oz. ; water, 6 oz. at 25° C. ; compressed English brewers' yeast, J oz. No. 6. Flour, 68 grams ; water, 6 oz. at 25° C. ; compressed English brewers' yeast, J oz. Date, October 23, 1885. No. 7. Sugar, J oz. ; water, 6 oz. at 25° C. ; compressed English brewers' yeast, J oz. No. 8. Flour, 68 grams ; water, 6 oz. at 25° C. ; compressed English brewers' yeast, J oz. No. 9. Flour, 68 grams ; sugar, f oz. ; water, 6 oz. at 25° C. ; com- pressed English brewers' yeast, J oz. No. 10. Sugar, J oz. ; water, 6 oz. at 25° C. ; Brighton brewers' yeast, as skimmed, J oz. JJo. 11. Flour, 68 grams ; water. 6 oz. at 25° C. ; Brighton brewers' yeast, \ oz. The following were the quantities of gas evolved in six hours : — No. 1 91 *2 cubic inches. No. 7 . . 80*3 cubic inches. No. 2 .. 40-8 No. 8 0*5 No. 3 .. 32-3 No. 9 . . 1*0 No. 4 .. 115.2 No. 10 .. 720 No. 5 . . 80-0 No. 11 .. DO No. 6 .. 1*9 Nos. 1 and 2 call for no special remark, being similar in character to many tests previously made. The quantity of flour in No. 3 is double that used in previous experiments, the object being to get a mixture which should be a nearer assimilation to dough, while still possessing sufflcient fluidity to permit the escape of the produced gas. As might be expected, the amount of gas evolved is higher than in tests where 34 grams were used. Nos. 4 and 5 were tests with the compressed brewers' yeast — there is a more rapid evolution of gas than in the corresponding tests with the French distillers' yeast ; so far, the verdict would be in favour of the English yeast as being a stronger yeast. This verdict is borne out by the results of commercial use of the yeast for brewing purposes. Next comes test No. 6, the results of which are most remarkable ; the English brewers' yeast, which had been by far the stronger in both yeast mixture and sugar solutions, causes practically no evolution of gas whatever from the flour mixture. On the next day some of the experiments were repeated, to- gether with others. No. 7 was a duplicate of No. 5 (with sugar) and yields similar results ; No. 8 was a duplicate of No. 6, and of the two, results in the production of still less gas ; therefore, the results of the first day's experi- ments were confirmed by those of the second. In No. 9, there was added, in addition to flour, a half-ounce of sugar, with the surprising result that in this case also only one cubic inch of gas was evolved in six hours. No. 10, in which a local brewers' yeast was used, showed an evolution of gas in large quantity ; but in No. 11 the same yeast caused an evolution of but one cubic inch of gas in six hours. The foregoing experiments were made on the date given in 1885, and were published by one of the authors in The Chemistry of Wheat, Flour, and Bread, in 1886. 218 THE TECHNOLOGY OF BREAD-MAKING. In further examination of this point the following experiments were made and published in 1895 : — No. 1. Sugar, 20 grams ; water, 200 c.c. at 30° C. ; distillers’ yeast, 1 gram. No. 2. Flour (soft English), 50 grams ; water, 200 c.c. at 30° C. ; dis- tillers’ yeast, 1 gram. No. 3. Sugar, 20 grams ; water, 200 c.c. at 30° C. ; brewers’ yeast (uncompressed), 2 grams. No. 4. Flour, 50 grams ; water, 200 c.c. at 30° C. ; brewers’ yeast, 2 grams. The following w^ere the quantities of gas evolved at the end of six hours : — No. 1 . . 334 cubic centimetres. No. 3 . . 516 cubic centimetres. No. 2 . . 345 „ „ I No. 4 . . 36 „ It will be noticed once more that whereas the brewers’ yeast gave more gas from sugar, yet it was practically inoperative on flour, confirming again the results of the previous series. Another set of experiments was next made in order to determine the effect of the presence of varying quantities of flour on the fermentation of brewers’ yeast and sugar. The following quantities were taken : — Sugar. Flour. Water. Brewers’ Yeast. No. 1. 10 grams. 0 grams. 200 C.C. 2 grams. No. 2. 55 10 „ 55 55 No. 3. 55 20 „ 55 No. 4. 55 30 „ 55 55 No. 5. 5 5 40 „ 55 55 No. 6. 55 50 „ 55 55 At the end of six hours the following quantities of gas had been evolved : — No. 1 No. 2 No. 3 . . 320 cubic centimetres. 50 20 55 No. 4 No. 5 No. 6 27 cubic centimetres. 17 „ The addition of 10 grams only of flour to No. 2 was sufficient to drop the evolution of gas from 320 c.c. to 50 c.c. in the six hours, while 20 grams of flour restricted the evolution of gas to 20 c.c. Beyond this amount an increase of flour did not cause a marked diminution in gas : in No.^ 4, in fact, the quantity of gas is more, due, doubtless, to some irregularity in the experiment. Nos. 5 and 6 had both evolved 17 c.c. in 4 hours, and remained stationary from that time onwards. In order to still further elucidate these points, the following experi- ments were made : — A Series. Sugar. No. 1. 10 grams. 0 No. 2. „ 5 No. 3. „ 10 No. 4. „ 20 Flour. Water. Brewers’ Yeast. grams. 200 c.c. 1 gram. 55 55 5 ? 55 55 55 55 5 ? In all cases fermentation was conducted at a temperature of 25° C. The following are the quantities of gas evolved in cubic centimetres, readings being taken at the end of each hour from the commencement. The figures opposite the brackets are the quantities of gas evolved in each separate hour : — TECHNICAL RESEARCHES ON FERMENTATION. 219 Gas Evolved. Time. No. 1. No. 2. No. 3. No. 4. 0 1 7 1 ^ 1 ! 1 11 1 hour. . 8 1 16 |l4 1 12 1 ^14 2 hours 23 i 1 20 20 25 1 1 1 1 [ 2 1 ^ 1 0 0 3 „ 25 1 20 20 25 1 ) i 1 [ 3 1 2 1 ^ 1 0 4 „ 28; \ \ 22 20 i 25; 1 \ 2 1 ^ 1 ^ 1 5 „ 30; 1 I 27 24 26; 1 1 20 1 ^ 1 ^ 4 6 50 ) 36^ 30^ CO o ) B Series. These were similar to A, except that compressed distillers" yeast was used throughout instead of brewers" yeast ; quantities as before, I gram. Gas Evolved. Time. No. 1. No. 2. No. 3. No, . 4 . 0 i 1 - 6 “1 9 *^1 ■ ^ 10 1 hour. . 11 9^ 1 HI U2 loj 20 2 hours 17j 1 Us 20 1 U5 20| i ' 1 [37 30 1 1 [47 3 „ 65; 1 [25 65 1 [15 ! 57; • 77 1 [ « 4 „ 90; [73 80; [37 66; ) [50 85; [20 5 „ 163 [84 117; [58 116 [72 105: [37 6 „ 247’ 175 ) 188' 142 ; A curious point in both these series of tests is the falling off in gas evo- lution during the middle portion of the time of fermentation. The fer- menting vessels of all the numbers of each series were placed in the same water-bath, and so were subjected to the same conditions of temperature. The two series, however, show the same characteristics in every case, though the tests w^ere made on different days. With brewers" yeast the addition of even smaller quantities of flour exerts in every case a retarding influence on the evolution of gas. The sample of yeast employed in these experiments was in the liquid form, and much weaker than some obtained for the tests described in preceding paragraphs. Some judgment must, therefore, be exercised in comparing the results of one series with others made at other times with totally different yeasts. Flour also exerted a retarding influence on the fermentation with dis- tillers" yeast. 220 THE TECHNOLOGY OF BREAD-MAKING. An attempt was next made to determine if possible which of the con- stituents of flour exerts the retarding influence. The most important of these are starch, gluten, and soluble proteins. A series of experiments with starch instead of flour was easily arranged. It is obviously impossible to incorporate gluten with water and sugar in the same, way as flour, water, and sugar can be mixed, so no direct experiments were made with gluten. In imitation of the soluble flour proteins, mixtures were made of water, sugar, and desiccated white of egg (albumin). Particulars follow of the various fermentation experiments : — C Series. Sugar. Wheat Starch. Water. Brewers’ Yeast. No. I. 10 grams. 0 grams. 200 c.c. 1 gram. No. 2. 5? b jj 55 yy No. 3. yy 10 5, yy No. 4. yy 20 „ Gas Evolved. yy Time. No. 1. No. 2. No. 3. No. 4. 0 1 , i »| ^1 1 5 1 1 1 ^ 5 1 hour. . H [ 2 ! 3 1 1 ' 3 5 8 13 : 2 hours vl 1 ! 8 8 1 1 1 [ 3 io{ 2 1 [ 4 10 1 3 yy 10 1 1 12j 23 ! 1 5 1 [ ^ 2 4 yy 15j 1 ' 1 [17 ! 15[ r 10 20 1 [18 25 i r® 1 40 5 yy 32 1 1 '12 25 1 35^ 10 38 1 [15 13 1 53^ 6 yy 44^ 1 53^ 1 D Series. These were similar to C, except that I gram of compressed distillers’ yeast was substituted for the brewers’ yeast. Gas Evolved. Time. No. 1. No. 2 . ' No. 3. No. 4. 0 *^1 1 t 9 Il5 1 [17 20 1 hour. . o] 1 15 1 nj 20 1 1 ■ 6 |l5 1 [16 19 2 hours 15 1 30 33! 1 1 39 1 1 [13 ll9 1 24 27 3 5, 28 1 49 57 [ 1 1 66 1 ^22 24 73 1 30 34 4 ‘55 50 1 1 87 1 \ \ 100 1 [45 50 47 50 5 5, 95! [35 123 20 143^ 134j 1 [33 150 35 185' 0 ,5 130^ 1 167^ 1 TECHNICAL RESEARCHES ON FERMENTATION. 221 With both brewers’ yeast and distillers’ yeast the presence of starch is accompanied by an increased evolution of gas. The increase is some- what erratic in the brewers’ yeast series, but still is very noticeable. With the distillers’ yeast, a regularly increasing amount is obtained with each increase of added starch. Wheat starch, then, cannot be viewed under these conditions as the agent of retardation : the curious point is its stimu- lating effect. This can scarcely be ascribed to the starch itself. Possibly a trace of stimulating nitrogenous matter was present in the starch. . E Series. Sugar. Albumin. Water. Brewers’ Yeast. No. 1. 10 grams. 0 grams. 200 c.c. 1 gram, No. 2. 55 0-5 „ 55 No. 3. 55 1-0 „ 55 No. 4. 55 2-0 „ 55 55 No. 5. 55 5-0 „ 55 55 Gas Evolved. E Series. These were similar to E, except that 1 gram of compressed distillers’ yeast was substituted for the brewers’ yeast. Gas Evolved. 222 THE TECHNOLOGY OF BREAD-MAKING. With both brewers’ and distillers’ yeasts, the addition of a small quantity of albumin, 0 *5 grams, depressed the evolution of gas ; with larger quantities a decidedly stimulating action occurred, due probably to more or less peptonisation of the protein. With starch and soluble protein matter eliminated from among the retarding agents, we must fall back on gluten as the probable effective body in slowing down the fermentation of flour and water. This effect is most likely due to its peculiar physical characters. As to why distillers’ yeast is so much better able to overcome this resistance of gluten than is brewers’ yeast is a matter still awaiting investigation. On the assumption that the explanation may possibly be found in there being differences in their power of inducing physical alteration, experiments were made to elucidate this point. Two doughs were machine-mixed from the following ingredi- ents : — No. 1, Spring American Second Patent Flour. . 840 grams Salt 9 „ Water . . . . . . . . . . 466 ,, Compressed Distillers’ Yeast . . . . 15 ,, No. 2 same as No. 1, except that 30 grams of liquid brewers’ yeast were substituted for the distillers’ yeast. The temperatures of the doughs when made was 83° F. ; they were kept warm, and covered with a damp cloth to prevent evaporation. At intervals, portions of each dough were removed, and kneaded to exactly the same extent in a small doughing machine, so as to drive out the whole of the gas. The stiffness of this dough was then tested by the viscometer (see Chapter XXVI.), and the percentage of gluten determined. The following are the results : — Comparative Tests with Distillers’ and Brewers’ Yeasts^ Time of Test. ■' No. 1, Distillers’. 1 No. 2, Brewers’. Viscometer Reading. Wet Gluten Per Cent. Dry Gluten Per Cent. Viscometer Reading. Wet Gluten Per Cent. Dry Gluten Per Cent. Immediate . . 110" 26-7 8-3 138" 1 28-7 9d 1 hour 94" 28-8 8-7 ‘ 73" ! 29-7 8-9 3 hours 173" 26-7 8-5 1 65" i 32-0 9-2 5 „ 96" 28-7 9-1 38" : 31-3 8-9 10 „ 50" 27-3 8-7 37" ; 30-7 9-2 22 „ 101" 28-7 8-9 60" 32-7 9-2 With No. 1, the viscometer result at the end of three hours was some- what anomalous, but was confirmed by a duplicate test. In each case there is a falling off in stiffness during the ten hours, but considerably more with the brewers’ than the compressed yeast. On standing over- night, tlie viscosity of both had risen. No great alteration occurs during this time in the percentage of dry gluten obtained, but in the case of the brewers’ yeast dough the gluten became much softer and more watery, this being shown by a marked increase in weight in the wet state. The greater softening of the gluten may be the cause of brewers’ made dough yielding a “ runny ” loaf ; but this does not account for the much slower evolution of gas wlien a thin batter of flour, water, and sugar is subjected to fermenta- tion. The probable solution of this problem is further dealt with in para- graph 378. 223 TECHNICAL RESEARCHES ON FERMENTATION. 377. Brewers* Yeast and Ferments. — ^When brewers’ yeast is employed for bread-making purposes it is usual first to allow the yeast to develop in a “ ferment,” generally composed of boiled potatoes rubbed down through a sieve into water, and a little raw flour added. In order to ascertain the effect of different substances as constituents of a “ ferment,” the following experiments were made : — Water. No. 1. Sugar, I gram . . . . . . 200 c.c. No. 2. Boiled potatoes, 5 grams . . . . ,, No. 3. Filtered potato juice, 10 grams . . ,, No. 4. Malt extract, 2*5 grams . . . . ,, No. 5. Diastatic malt extract, 2*5 grams. . ,, No. 6. ,, ,, ,, killed, 2*5 grams ,, No. 6. was precisely similar to No. 5, except that the solution had been raised to the boiling point, with the view of destroying the diastase present. The following were the quantities of gas evolved after six and a half hours’ fermentation at 30° C. : — Brewers’ Yeast. 2 grams. No. I . . 125 cubic centimetres. No. 2 . . 25 No. 3 .. 16 No. 4 . . 160 cubic centimetres. No. 5 .. 76 No. 6 . . 74 After fermentation had ceased, and about twenty hours from the com- mencement of the experiment, 50 grams of flour were added to each “ fer- ment,’' and the bottle again immersed in the bath at 30° C., and readings taken of the quantities of gas evolved. At the end of six hours, these were : — No. 1 . . 23 cubic centimetres. i No. 4 . . 43 cubic centimetres. No. 2 ..11 „ > No. 5 .. 15“ No. 3 . . 31 „ : No. 6 . . 30 As a ferment constituent potato juice causes the evolution of less gas than do potatoes, while as a stimulant on the yeast’s after-power of inducing fermentation in flour the juice is far the more efficacious. While the gas evolved in the two diastatic malt extract solutions is practically the same, that in which the diastase had been destroyed acted in this case as the more energetic after-stimulant of flour fermentation. Possibly a concentrated solution of diastase may exert some retarding influence on the energy of yeast. In an experiment conducted in this fashion the action of the yeast in the mixture of flour and water is less in all cases, except No. 4, than when the yeast and flour mixture are fermented direct (36 cubic centimetres). During the working of the “ ferment,” the operation was carried on without access of air, a condition which may have had a retarding action on the energy of the yeast {Science and Art of Bread-making, Jago, 1895, p. 223, et seq.). 378. Toxicity of Flour to Yeast. — ^In view of recent investigations on the toxic behaviour of flour towards yeast, the experiments described in the foregoing paragraphs have some historic interest. They serve to show that flour retards the fermentative action on sugar of both distillers’ and brewers’ yeasts, but that the latter is far more affected. That the retardation is not due either to starch or carbohydrate bodies is very appar- ent. Soluble proteins in the form of egg-albumin are shown to possess little or no retarding effect, though this is scarcely conclusive, since egg- albumin and soluble wheat proteins are not necessarily identical in this respect. Finally by a process of elimination, rather than direct proof, the suggestion is made that the inhibitive action is due to the gluten of the flour, though the gluten action was evidently regarded rather as a physical than a chemical one. In this relation it is interesting to note 224 THE TECHNOLOGY OF BREAD-MAKING. the work that has been done on what are called “ toxalbumins."' In investi- gations carried out on the proteins of the seed of Ricinus, it has been shown that its toxic property belongs to the protein, and is closely related to the proportion of coagulable albumin contained in various fractions of the seed protein. It seems, therefore, almost certain that true toxalbumins occur in seeds {The Vegetable Proteins, Osborne, 1909, p. 96). Michaelis has also pointed out that foreign protein matter is under all circumstances a deadly poison for yeast, and that this is rendered innocuous by the proteolytic enzyme present. Baker and Hulton have recently (1909, 1910) re-investigated this matter, and have confirmed the just quoted conclusions of one of the authors, viz., that the presence of flour inhibits the fermentation of a solution of sugar by brewers’ yeast. Independently, Lange, in the course of a series of investigations, conducted in 1904 and 1905, re-discovered that the flour of wheat and certain other grains exercised a poisonous action on yeast, and especially brewers’ types of yeast. The following is a synopsis of the work and conclusions of Lange, Henneberg, Hay duck, Wendel, Baker, and Hulton on this and closely allied subjects. The authors are indebted to the Treatise on Brewing by Sykes and Ling for a resume of a lecture by Delbriick before the London section of the Institute of Brewing in 1906, from wfiiich many of the conclusions of the above named German authorities are gleaned. The lecture is reported more fully in Journ. Inst. Brewing, 1906, 642. From Hayduck’s researches, the lecturer, Delbriick, derived the laws that in the production of yeast, the fermenting power is in inverse ratio to the multiplication of the yeast-cells. Moderate multiplication produced a yeast rich in protein ; a rapid multiplication, on the other hand, produced a yeast poor in protein. Therefore everything which hindered multiplica- tion, such as a low temperature, the shutting off of air, lack of movement, fermentation under carbon dioxide pressure, conduced to the yielding of a yeast which was rich in protein and in fermenting power. Obviously, therefore, these are among the matters to be considered in the manufacture of a vigorous yeast. It is also evident that such treatment must not be carried to extremes, since an undue restriction of multiplication would seriously restrict the output of yeast. In yeast manufacture the con- ditions must be so balanced as to obtain the maximum of vigour combined with a fair production of yeast. Delbriick also dealt with the inquiry which is so frequently made, Wliat important physiological significance has the peculiar dynamic effect of the splitting up of sugar into alcohol and carbon dioxide ? To this he replies that it is easy to say that a sort of subtle respiration process was going on here — that the cleavage was a hidden source of heat ; but the significance of this activity was, particularly from a zy mo -technological point of view, far more comprehensive. It w^as known that the most powerful defensive agencies of the yeast against the attacks of foreign organisms lay in its fermentation energy. Delbriick had always looked upon the fermentative effect of the yeast in this light, and had demon- strated that its organism, in sending out carbon dioxide and alcohol, thus protected itself against all the organisms for which these substances were j)oisonous. Tlie effect of the carbon dioxide is ten times as deadly as that of tlie alcohol. Delbriick therefore arrives at the conclusion that zymfise (the yeast enzyme which decomposes sugar into alcohol and carbon dioxide) is not only a respiration enzyme, but also a fighting enzyme. He also regards the proteolytic enzyme of yeast, as a part of its fighting organisa- , tion, inasmuch as it attacks all inimical organisms, dissolving and killing them. As already mentioned, foreign protein matter is a poison to yeast, j and this is rendered innocuous by the action of the proteolytic enzyme by || TECHNICAL RESEARCHES ON FERMENTATION. 225 M^iich it is degraded. The law that in the struggle for existence, those organisms which specialised in the production of fighting substances and in the cultivation of fighting enzymes, would be the strongest, applies especially to the micro-organisms. Lactic acid bacteria possessed means of defence in the lactic acid enzyme, while the butyric acid bacteria were similarly protected by the production of butyric acid, a substance which is pernicious in its effects on other organisms. It was in the course of these researches that Lange independently re-discovered that bruised grain (or bran) or meal, or even an aqueous extract of them, had a poisonous effect on yeast. He further found that different kinds of yeast varied in susceptibility to this poisonous action. Thus the distillers' yeast races were capable of offering resistance, but such power was less marked in brewers' top -fermentation yeast, and still less so in the bottom-fermentation type of brewers' yeast. As to the nature of these poisonous substances, there was some probability that they belonged to the proteins and to the enzymes produced by them, since the injurious action could be neutralised by heating the grain or its aqueous extract. The following are some of the more important conclusions of the German authorities. The toxic action only becomes manifest when the yeast and cereals are present together in distilled water. Rye, wheat, and barley, in the form of grits or flour, placed with bottom-fermentation beer-yeast in a solution of saccharose, will kill up to 99 per cent, of the yeast in a few minutes. Maize and oats do not show this toxic action. By agitation with distilled water, the flour of rye and wheat furnish extracts that are also toxic toward beer-yeast, but to a far less extent than the corresponding solid substances. The protein sludge separating from the coarser particles when rye grits are shaken up with water is specially poisonous. The same effect is produced by the glutinous mass obtained by kneading wheaten flour under water. It is probable that the toxic substance must be sought among the proteins, or may be produced therefrom by the action of the yeast. All these toxie effects are completely obviated by the addition of a small quantity of inorganic salts to the solution, lime salts being the most effective, and next to them magnesia salts. A partial or complete removal of the toxic action can be effected even by replacing distilled water by tap-water. Among other substances exerting a strongly poisonous action on low- fermentation beer-yeast is egg -albumin. Wheaten flour seems also to exert a toxic action on high-fermentation distilling yeast, but this requires confirmation {Treatise on Brewing, Sykes and Ling). These conclusions, it will be noticed, apply to bottom-fermentation beer-yeast, whereas in the experiments previously described as having been made by one of the authors top -fermentation beer-yeast was employed. This, although admittedly less susceptible to the inhibitory action of the active cereals, is nevertheless similarly affected. Further, in these experi- ments, no definite retarding action was caused by the addition of egg- albumin. It is possible that the low temperature evaporation of this body to dryness in the preparation of the desiccated product may have modified its inhibitive action. 379. Baker and Hulton’s Researches. — ^In 1909, these writers communi- cated to the Society of Chemical Industry the results of some researches on the action of wheaten flour on brewers' yeast. This was followed by a paper on The “Toxins in Cereals,” which appeared in the Journal of the Institute of Brewing in 1910. The experimental work confirms that pre- viously described, and among other things goes to show that with mixtures of flour and water, tap-water enables a greater amount of gas to be evolved than does distilled water. Thus with 20 grams of Hungarian flour, 50 c.c. Q 226 THE TECHNOLOGY OF BREAD-MAKING. of water, and 1 gram of unwashed pressed brewers’ yeast, fermented at 110° F., the following results were obtained at the end of four hours ; — Carbon Dioxide Evolved. Brewers’ Yeast and Distilled Water . . . . 10 c.c. Distillers’ ,, ,, ,, .... 287 „ Brewers’ Yeast and Tap- water . . . . . . 35 ,, Distillers’ ,, „ • • • • • • 287 „ The tap- water contained in grains per gallon : — Total Solids 2142 Solids after ignition . . . . . . . . . . 19*74 Silica 0*28 Lime . . . . . . . . . . . . . . 7*60 Magnesia . . . . . . . . . . . . . . 0*71 Sulphuric Acid (SO 3 ) . . . . . . . . . . 2*69 Potash . . . . . . . . . . . . . . 0*42 Soda . . . . . . . . . . . . . . 1*26 Chlorine . . . . . . . . . . . . . . 1*40 Nitric Acid (N 2 O 5 ) . . . . . . . . . . 0*31 Using the tap-water it will be noticed that the activity of the brewers’ yeast is much increased. On examination of the results caused by the addition of various inorganic salts to tap-water, it was found that potassium sulphate, calcium chloride, sodium chloride, and many other salts act as accelerants. Baker and Hulton regard potassium sulphate as the most favourable of these, and find that a solution containing 0*6 gram per 100 c.c. exerts a very decided accelerating action. They make the follow- ing suggestion as to the reason of the difference between the two yeasts (distillers’ and brewers’) — In a distillery wash, before the yeast is introduced, there are present large quantities of raw cereals, such as barley and rye, containing toxins, and since the distiller pitches his yeast into unboiled wort and therefore one with this cereal poison still active, only those yeast cells which can survive and are immune to such toxic substances and can reproduce in this environment will carry on the race, giving rise to cells inheriting this advantageous variation. There will thus be obtained in a few generations by natural selection what is to all intents a new species bearing this char- acter of immunity to cereal poison. Mdien such yeast is used for bread- making, where it is again exposed to the action of the toxic substance in wheaten flour, the high gas yield at once shows that it is now immune, wliile brewers’ yeast which has always been grown in a boiled, and therefore non-poisonous wort, is readily susceptible. The accelerating influence of potassium sulphate, sodium chloride, etc., on the fermentation of flour with brewers’ yeast is thus seen to be correlated with the protective function these salts exert on the yeast by negativing the toxic effect of the flour, wliile distillery yeast which is already immune to these toxins, from having been grown in their presence, needs no such protection, and is, in fact, not activated by these salts {Journ. Inst. Chem., July, 1909). Baker and Hulton do not attribute the protective action of potassium sulphate to any “ salting out ” of proteins, but conceive that it may lie in some kind of physiological stimulation of the yeast, whereby it is rendered [ more, resistant to an unsuitable environment. They further point out | that brewers’ yeast, which was formerly used for bread-making, is now | practically useless, tlie reason being possibly due to the fact that modern ! flours being better milled contain a smaller proportion of fibre, husk, etc., | than formerly. The husk probably has a protective action towards brewers’ yeast similar to that of salts (“ Toxins in Cereals,” Journ. Inst. Brewing, xvi, April, 1910). 11 TECHNICAL RESEARCHES ON FERMENTATION. 227 In making this suggestion the writers have apparently overlooked the fact that when brewers’ yeast was so largely employed for bread-making, it was the custom to use a ferment consisting of boiled potatoes with their skins on, the water in which they were boiled, and raw flour. The yeast was allowed to work and multiply in this mixture before being introduced into the sponge (earlier dough stage). The stimulating effect of potatoes as an agent in fermentation has been already described in paragraphs 372 and 373. Experimental Work. 380. The student who has the opportunity will do well to perform for himself most of the experiments described in this chapter, and compare the results he obtains with those here recorded. He should commence by making duplicate tests with the same yeasts, in order to gain the requisite accuracy and practice in working. The experiments described in the 365th and following paragraphs, or as many of them as practicable, should be performed. It is recommended that 25° C. be adopted as the standard temperature throughout the experiments, instead of 30° C. Practical directions follow. 381. Apparatus requisite. — ^Water-bath to hold yeast bottles, sets of yeast testing apparatus, pneumatic troughs, bunsen burner and automatic temperature regulator, thermometer, etc. The water-bath may conveniently consist of a large iron saucepan (or Scotch “ goblet ”) ; to this should be attached a side-tube, by means of which the height of the water in the bath may be regulated : for description of this very useful device see “ The Hot- Water Oven,” Chapter XXVI. Adjust the height of the water in the bath, so that the yeast bottles, when charged, shall be on the verge of floating, the surface of the liquid in the bottle will then be about an inch below that of the water in the bath. During very hot weather, and particularly when working at the lower temperatures, it is advisable to have a stream of cold water running through the bath. For this purpose, lead the end of a piece of bent tube, connected with a water tap, into the bath over the top, on the opposite side to side-tube before referred to : turn on a small stream of water through this bent tube, scarcely more than what would cause rapid dropping from its end. Water will then be con- tinually finding its way in through this tube, and making its exit through the side-tube : thus lowering the temperature when necessary. Do not let the stream from this cold water tube impinge directly on either of the yeast bottles. The construction and arrangement of the yeast testing apparatus and pneumatic troughs have already been sufficiently fully described. 382. Automatic Temperature Regulator. — ^The bath is warmed b}^ means of a bunsen burner arranged underneath, and, in order to maintain the temperature at any desired point, an automatic regulator is employed. As an unvarying temperature is necessary for several other chemical opera- tions, a detailed description of such an automatic regulator is given. There are several of these instruments made and sold under various names ; but for general purposes the following modification, designed by one of the authors, and shown in Fig. 22, is simple and not likely to get out of order. The instrument consists of a bulb, a, about 4 inches long, and | inch in diameter ; to this is attached a stem, h b, about a J inch diameter, and 6 inches long. This stem bends over at the top, and is connected with a U-tube, c d e, ^ inch diameter, in which are blown 2 bulbs as figured, / /, about I inch diameter. The one end, c, of this U-tube is closed with a .stopper, g, which is ground in with extreme accuracy. From the centre 228 THE TECHNOLOGY OF BREAD-MAKING. of the bottom of this stopper, a hole is bored upwards for a short distance, which hole joins another bored inwards through the side of the stopper ; this hole, therefore, affords a passage up through the ^ ^ bottom of the stopper and out through its side. A cor- / 5^ responding hole is bored through the side of the neck, c, of the U-tube, so that if the stopper be turned so that these two holes coincide, a passage is provided from the U-tube to the exterior ; this exit may be closed at will by slightly turning this stopper, g. To the other end, c, of the U-tube, c d e, is sealed a bent tube, h i j ; below the point, e, this tube, h i j, is made much finer, having its smaller end, j, inch in diameter, and ground obliquely as shown in the figure. Below the joint, e, but as near to it as possible, an outlet tube, hi, is sealed into the U-tube, c d e. This completes the regulator ; the method of using the instrument, and its principle, may be conveniently described together. By means of a screw-clamp carried on a retort- stand, or any other suitable holder, fix the regulator upright, and so that the bulb, a, shall be wholly im- mersed in the water of the bath, and the ends of the tubes, h and I, projecting over its side. The regulator should be perfectly rigid when fixed ; the clamp is best screwed on to the stem, h h. Connect up h by india- rubber tubing with the gas tap, and join up I to the bun- sen burner. Partly fill the U-tube, c d e, with care- fully cleaned mercury through c. Turn on the gas and light the bunsen burner, then continue the filling oi c d e with mercury until the level rises sufficiently high in the limb, d e, to very nearly close the end of jet j. The quantity of mercury added should be suffi- cient to just begin to shut off the supply of gas to the bunsen ; it is evident that then a very slight rise in level of the mercury would either considerably diminish or entirely shut off the gas from the burner. Next heat a little india-rubber sufficiently to liquefy it ; smear the stopper, g, and its neck with this liquid, taking care to preserve a clear passage through the hole in the stopper. Then pour some of the strongest alcohol obtainable, which has been recently boiled, through c, until the bulb, a, its stem, h h, and the part of c are completely ^ filled with alcohol. Insert the stopper, g, so that the hole through it is open ; the excess of spirit escapes. It sometimes happens, in filling the instrument with spirits, Regulator. that the level of the mercury in the U-tube is dis- turbed, the spirits floating on its surface at c, for- cing up the level in e sufficiently far to entirely close the jet, j. Should this happen, the mercury must again be adjusted by removing a small drop by means of a fine pipette. Having made these adjustments, the instrument may be regulated for any desired temperature. Place a ther- mometer in the bath, so that the height of the mercury can be easily read and that its bulb does not touch the bottom. Suppose it is wished to maintain the bath at 25° C., turn the stopper, g, so that the hole is open, and light up the burner. The gas finds its way through the tubes, h i j h I, in the directions of the arrows. As the temperature of the water m the bath increases, so does that of the spirits in a. With a rise in temperature a TECHNICAL RESEARCHES ON FERMENTATION. 229 the alcohol expands, and a small portion finds its way out through the hole in the stopper, g. Watch the thermometer carefully, and when the temperature stands at about one- tenth of a degree below 25° C., turn the stopper, g, so as to close the hole through it. The spirits, in expanding, now find no means of escape, and therefore drive down the mercury in c d, causing a corresponding rise in d e \ the consequence is that the jet, j, is either wholly or partly closed, and the gas either completely or partly shut off from the burner. The bunsen used should have a cap of fine wire gauze fastened on to it, so as to prevent its lighting at the bottom when the flame is turned very low. A small pin-hole burner should be fixed to the bunsen, and fed from an independent supply, so as to re-light it should the regulator turn it completely out ; this “ pilot burner must be turned down so as to only give a flame about J inch high, and should not be able to appreciably warm the bath. The regulator will at first most likeiy shut off the gas completely ; the bath will then cool slightly, and as the alcohol in a contracts, the level of the mercury in d e will fall, and so the jet, j, will once more be opened, and a passage of gas to the burner permitted. With this regulator properly set, the temperature keeps between two extremes that after a short time closely approach each other ; in fact, the mercury so adjusts itself as to partly close the aperture j, allowing just sufficient gas to pass to keep the bath at a constant temperature. The end of j is cut obliquely in order to prevent the mercury sticking to it, and so acting irregularly. Alcohol is used in a instead of air, because it is not affected by changes of atmospheric pressure ; when temperatures above the boiling point of alcohol are required, the instrument must be used with air, or else some liquid having a sufficiently high boiling point. Alcohol is preferable to water, because it has a much higher co-efficient of expansion, that is, for an equal rise in temperature it expands much more. With the instrument set as described, it should maintain the temperature closely at 25° C. ; if it should be found to be somewhat higher, the instru- ment may be made more delicate by adding a very little more mercury, or it may be shut off somewhat earlier ; thus, if it be found to give a con- stant temperature 0*4° over that at which the stopper, g, is shut off, then all that is necessary is to always shut off at 0*4° below any temperature that may be required. Should the temperature be too low, it may be raised •slightly by carefully turning the stopper, g, momentarily, until the slightest drop of spirits oozes out ; if the temperature is too high, the bath must be cooled down, and again regulated on the rising temperature. If the bath is required to be used for several days at the same temperature, all that is requisite is to turn off the gas when the day’s work is done ; as the bath cools, the mercury rises in c d through contraction of the alcohol ; the bulbs, / /, are provided in order to allow of this rise without its altering the regulator. When the bath is next required, simply turn on the gas, and the regulator, without any attention, will maintain the temperature ■at the point for which it was adjusted. The advantage of this form of regulator is that it keeps perfectly constant for a very long time, as there are no parts to shift, or places from which leakage may occur ; the stopper, •g, smeared with melted india-rubber, is perfectly air-tight. Grease will not answer as well as the india-rubber, as it is dissolved by the alcohol. 383. Method of Testing. — ^To make one or more experiments proceed in the following manner : — First, carefully enter in the notebook the particulars of each experiment, and number them : place corresponding numbers on the bottles. Regulate the water-bath at the desired tempera- ture, and place in it a flask containing sufficient water for the experiments ithat are to be made. Having cleaned the whole apparatus, arrange in 230 THE TECHNOLOGY OF BREAD-MAKING order the generating bottles required, and weigh out and introduce into them the yeast mixture or other substance to be fermented. Next weigh the yeast, taking care that a good representative sample is obtained. With pressed yeast cut a thin slice off the middle of the slab, avoiding dry and crumbling fragments. Brewers" yeast must first be well stirred, and then weighed out in a counterpoised dish. Break up the pressed yeast carefully in a small evaporating basin, with some of the water which has been raised to the right temperature ; for this purpose an india-rubber finger stall placed on the finger is useful. Pour the yeast and water into the bottle ; rinse the basin with the remainder of the six ounces of water. As rapidly as possible introduce each sample of yeast, to be tested, in its respective bottle in precisely the same manner. Having introduced the yeast, yeast mixture, or other substance, and water, into the respective bottles, gently shake each bottle so as to thoroughly mix the ingredients ; then tightly cork each bottle, and arrange the apparatus as shown in Fig. 21, given at the commencement of the chapter. Remove the glass stopper at d, and suck out the air from the apparatus until the water or brine rises in the jar, /, somewhat above the zero, then again insert the glass stopper. Pinch the india-rubber tubing on one side of d so as to make a slight opening, and thus permit air to enter ; in this way lower the liquid in / until its level exactly coincides with the zero. Perform this operation as rapidly as possible with all the apparatus being used, and note the exact time in the notebook. As the fermentation proceeds, the surface of the liquid in the jars will become lower, and in this way a measure of the amount of gas yielded is obtained. At the end of every half-hour or hour from the commencement, read off the volume of gas, and enter the same in the note- book. When the jars are nearly full of gas watch them carefully, and as soon as the 100 cubic inches, or 500 c.c., mark is reached, withdraw the plug at d, blow into the jar for a few seconds so as to displace carbon dioxide through the bottom, and then suck out the air until the liquid again rises to the top of jar, re-insert the plug, and rapidly adjust the surface of the liquid to the zero. This operation should last only a very short time, and does not practically affect the results that are being obtained. The readings may be taken for from, say, two to six hours ; or, if wished, until the action ceases. These directions apply equally to the ordinary use of the apparatus for testing the strength of yeasts. With the alternative displacement apparatus, the earlier part of the procedure is the same. The difference in the mode of collecting and measuring the evolved gas has been already sufficiently explained. 384. Preparation of Yeast Mixture. — It is essential that the substances composing this mixture be thoroughly mixed. The following is the best mode of procedure. First, dry tlie substances at a gentle heat (100° C.). In the laboratory this is done by placing them in a hot-water oven ; then finely powder each in a mortar, and weigh out the right quantities. Then thorouglily mix the first four ingredients ; afterwards add the fifth, and again mix ; then add the sugar little by little, mixing between each addition. In this way an equal composition of the mixture throughout is assured. Coarse crystalline coffee sugar is almost chemically pure ; failing this, the best loaf sugar may be used. The pepsin necessary for the experiments may be obtained from the chemist. The malt wort may be prepared by infusing coarsely ground malt with ten times its weight of water for two hours at 65° C. : it is then filtered and diluted down with w'ater until at the right density. In experiments w ith flour, the flour and part of the water should first TECHNICAL RESEARCHES ON FERMENTATION. 231 be placed in the generating bottle, and thoroughly shaken before the addition of yeast. In experiments with flour, the flour and part of the water should first be placed in the generating bottle, and thoroughly shaken before the addition of yeast. The starch is gelatinised by allowing it to stand in a small beaker, with some water, for about five minutes in the hot water-bath, stirring thoroughly meanwhile. The experiments on flour infusion, in which the sugar is determined before and after the fermentation, are very important, but had better be postponed until the student has proceeded with his studies of analysis. In the temperature experiments the tests at the same temperature should be made on the same day, and the complete series with as little interval as possible between. In addition to the experiments described in this chapter, many others will suggest themselves to the practical baker : these he may arrange for himself, and use the yeast apparatus as a means of measuring the evolution of gas, under any conditions that may be of interest to him. The student will do well, in addition, to perform the following series of tests. 385. Keeping Properties of Different Yeasts. — Procure samples as fresh as possible of different pressed, brewers’, and patent yeasts. Test immedi- ately after procuring them ; then store in a cool cellar, and test each sample on successive days until they are eapable of setting up little or no fermenta- tion. To ensure perfect accuracy it is well to keep each sample of yeast in a weighed vessel ; any loss by evaporation may then in the case of the liquid yeasts be made up each day by the addition of distilled water. The pressed yeast may be kept in a stoppered bottle, or, preferably, the portion for each estimation should be taken from the interior of the mass ; as a check, moisture should then be estimated in the yeast each day. 386. Use of Testing Apparatus without Temperature Regulator. — In the foregoing descriptions given it has been directed that the yeast bottle stand in a water-bath regulated by an automatic temperature regulator. While such an arrangement is extremely useful, it is not absolutely necessary. For actual bakehouse use the following plan answers well. Select a place somewhere near the oven where the temperature is pretty constant, and, if possible, between 70° and 80° F. Arrange on a shelf, clamped to the wall, a saucepan sufficiently large to take the yeast bottles, and fix the trough for the graduated jar in position. The saucepan will have to be raised sufficiently high by means of blocking ; this should be properly done at the outset, as the apparatus should remain there permanently. When about to use the apparatus, first of all fill the saucepan with water at the desired temperature F., and then make the estimation. A warm place being chosen, the water in the saucepan will not fall very much in temperature during the time necessary for carrying out the experiment. This method of using the apparatus applies more particularly to yeast testing than to the more delicate experiments described in the preceding pages. CHAPTER XII. MANUFACTURE OF YEASTS. 387. For baking purposes three commercial varieties of yeast are em- ployed, namely, Brewers’, Distillers’ Compressed, and “ Patent ” yeasts. These latter may again be subdivided into malt and hop yeasts as used in England, and the Scotch flour barms. The superior quality of the dis- tillers’ compressed yeast has led to its now being used to the almost entire exclusion of the other kinds. Still there are districts where distillers’ yeast cannot be obtained, and therefore bakers still have to manufacture their o^vn “ patent ” yeast. Descriptions follow of how these different types of yeast are manufactured. Brewers’ Yeast. 388. In the chapter on Fermentation an account is given of the appear- ance of an actively fermenting tun of brewers’ wort. The brewer first treats his malt with water at a temperature of about 65° C. for about two hours, more or less ; during that time the starch of the malt is converted into dextrin and maltose. The liquor is then allowed to drain from the grains, or husks of malt, and is transferred to a copper in which it is boiled with hops : the hops are removed and the wort rapidly cooled, either- by being exposed to the air in shallow open coolers, or poured over a specially arranged apparatus, consisting of a series of pipes through which cold water is passing, and which is termed a refrigerator. This cooling must be done as rapidly as possible, as a temperature of about 30° C. is particularly suited to the rapid growth and development of disease ferments. On the wort being cooled toTSor 19° C. (65° F.), about one one-hundred and fiftieth part of its weight of yeast from a previous brewing is added. Fermentation sets in, and after a time yeast rises to the surface, and is skimmed off. The flrst is rejected because any lactic ferments or other bacteria that may be present are, from their small size, floated up to the surface with the yeast on its flrst ascent. At the time when the fermentation is most active and vigorous, the best yeast is being produced. As fermentation slackens, cells are thrown to the surface which have been grown in a comparatively exhausted medium. Such yeast is weak, and possesses less vitality. For their own pitching purposes, the brewers reserve the middle yeast. Bakers who use brewers’ yeast should be supplied with that equal in quality to what the brewer himself uses for starting fermentation. The yeast, when skimmed, should be stored in shallow vats, so as to admit of free access of atmospheric oxygen. In some breweries the beer is allowed to finish its fermentation in large casks, arranged so that the bung-hole is very slightly on one side : the yeasty slowly works out of the bung-hole and flows in a shallow stream down the outside of the cask until it reaches the bottom, when it drops in a gutter arranged to receive it. A number of these casks are usually arranged side by side, and connected together by a pipe at the bottom ; they are consequently technically termed “ unions.” The one gutter receives the yeast from the series of unions and conveys it to the proper receptacle. 232 MANUFACTURE OF YEASTS. 233 Tlie yeast from these unions is found to make far better bread than that .skimmed from large fermenting tuns. The reason is that the yeast gets thoroughly aerated during its flow down the side of the cask. For baking purposes, the thorough aeration of yeast is essential. 389. Employment of Brewers’ Yeast. — Brewers' yeast is used in the pro- duction of what is called “ farmhouse " bread : it is supposed to produce a sweeter flavoured loaf than do other varieties. On the other hand, brewers’ yeasts darken the colour of bread. For reasons explained in the preceding chapter, for bakers’ purposes, brewers’ yeast is weak, and if used alone must be employed in considerable quantity. Almost invariably a potato ferment, or some substitute therefore, is employed together with brewers’ yeast. It is apt when freely used to impart a bitter taste to the bread : this may be in part obviated by washing the yeast, but even then it is exceedingly difficult to remove the bitter taste. Particularly in summer time brewer’s yeast is found to be very unreliable and uncertain in its actions. Even those bakers who prefer brewers’ yeast, when they can procure it good, find themselves compelled to resort to compressed yeast during the hot summer months. In selecting a brewers’ yeast for bakers’ purposes, those breweries should be avoided where large quantities of sugar or other malt substitutes are used instead of malt itself. Such brewing mixtures contain a deficiency of appropriate nitrogenous matters, and, although the resultant beer is sounder, and better meets the present requirements of the public, the yeast produced is, from the bakers’ standpoint, weak and impoverished through ill nourishment. 390. Microscopic Examination of Yeast. — This operation requires a fair amount of experience before a trustworthy judgment can be formed. For the examination of yeast under the microscope, it should be diluted with water until so weak as simply to give a milky appearance to the water. A minute drop is then put on a slide, over which a cover is gently placed. In microscopically examining yeast, there are two distinct points to be observed : first, the presence or absence of disease ferments, bacteria, etc. ; second, the appearance of the yeast cells themselves. For satisfactory work, a power of six or eight hundred diameters is necessary : the objective must be a good one, giving not only magnification, but also clear and accurate definition. It is a good plan to use a microscope in which several objectives are fastened to one “ nose-piece,” so that the powers may be changed instantaneously, without the trouble of unscrewing the one objective and then replacing it by another. Working with an instrument the yeast may first be examined with a magnification of about 440 diameters, and then, having seen the aspect of a fairly large field, a few typical ceUs may be observed more closely with a magnifying power of about 1000 diameters. First, with regard to the presence or absence of foreign ferments. The fewer of these the better the yeast. A yeast for bakers’ purposes needs to be judged by a somewhat different standard to that adopted by the brewer. To the latter, the presence of lactic or but3rric ferments or other disease organisms means that, during the period the beer is stored before it is all consumed, there is ample time for changes to go on which will result in either a marked deterioration or spoiling of the beer. But if this change does not make itseK rperceptible until, say two or three weeks have elapsed, it follows, as bread is fermented, baked and eaten within about three days, that under ordinary circumstances such changes cannot take place in bread. This explanation is necessary, because it is well known as a matter of fact that many bakers do succeed in producing very good bread, who use a yeast in which there is frequently an abundance of foreign organisms. It 234 THE TECHNOLOGY OF BREAD-MAKING. will in such cases, however, be found that they take special precautions which serve to prevent an injurious action of these during fermentation. Summing up, yeasts may be used by bakers which could not possibly be employed by the brewer, because the fermenting process of the former is so much shorter ; nevertheless an excess of disease ferments may set up injurious action even during the time of panary fermentation unless special precautions are taken. It is consequently safely laid down that the fewer of these foreign organisms the better. The presence or absence of disease ferments affords a valuable indication as to the previous history of the yeast, apart from their own specific action on the dough. A yeast largely contaminated with foreign organisms has been badly made : unsound malt will very likely have been used for its manufacture, and the whole process of fermentation conducted in dirty vessels. As in a brewer’s yeast the presence of disease ferments tells us this of its previous history, the yeast should be condemned, because, when carelessly produced under such unfavourable conditions, the yeast itself is likely to be unsound, or at least very uncertain in its quality. Secondly, with reference to the yeast cells themselves, the actual shape of the cells will vary with its origin. Ordinary English brewers’ yeast consists of round cells, but Burton yeast is oval ; so also is that in other districts where very hard water is used. With any yeast the cells should be about equal in size ; not irregular, with some very large and others small. The cells should be isolated, or at most only attached in pairs ; where they occur in large colonies, the yeast is too young, and has not had time to thoroughly mature. The cells should appear plump and not shrunken. The cell-walls should be of moderate thickness : if very thin the yeast is too young, and has not attained maturity ; on the other hand, very thick integuments denote an old, worked out yeast. Thin cells-walls may also be due not only to very young yeast, but also to the yeast being over kept long enough for the breaking down of the walls to have com- menced : under these circumstances the protoplasm of the interior of the cells is seen to be broken down and frequently exhibits a “ Brownian ” movement. If in this condition, the yeast is far gone, and will be found weak and exhausted for bread-making. As in this operation yeast does not bud or reproduce, but does its work in virtue of the energy and vitality of the original cells introduced, it is in the highest degree important that these cells should be strong, healthy, and, as far as is possible, in full maturity ; when in this condition, the contents of the cells should show slight granula- tions. Each cell should have one, or at most two, vacuoles ; but when placed in a drop of clear beer wort on the slide, the fluid should rapidly penetrate the cell-walls, causing the contents to become lighter, and the vacuoles to disappear. These changes occur but slowly in old cells that have been worked for a long time. In Plate II., Chapter IX., illustrations have already been given of different varieties of yeast employed by the baker. The drawings of brewers’ yeast for this plate were made in the summer, and represent samples of brewers’ yeast during practically the hottest weather of the year. The specimens marked a and h were taken from two London samples of yeast, | as sold to London bakers by yeast merchants. A considerable number | of disease ferments are present in both, marking them as being in an unhealthy ; condition. It is to be feared that often sufficient care is not taken for the I storage and preservation of yeast, especially during the hot weather, by j those who collect brewers’ yeast for redistribution among bakers. For ; purposes of comparison, some yeast was obtained from a Brighton brewery : this is figured in section c. It was found to be far away purer than either i of the London samples ; one or two bacteria are shown in the sketch, but ! MANUFACTURE OF YEASTS. 235 there were several microscopic fields that contained no foreign ferments whatever. In general aspect, the cells of yeast c were firmer in outline, the walls being thicker while the interior matter showed more distinct and darker granulations. It should be added that in these drawings the estimated magnification is only approximate. In every case w^here it is wished to ascertain exact dimensions, the eye-piece micrometer should be called into requisition. Manufacture of Compressed Yeasts. 391. These yeasts are now^ so w idely and successfully used that an account of their origin and mode of manufacture claims a place in this work. They find their way into this country from Holland and France, and are also largely manufactured in the United Kingdom. They are not, as has been stated, low or bottom yeasts of lager beer fermentation, but are distillers’ yeasts, and are formed as the principal product in the manufacture of spirits from malt and raw grain ; the spirits being used in the manufacture and treatment of liqueurs, perfumes, wine, and brandy. This manufacture can only be successfully conducted on a very large scale, and cannot be imitated by the baker who simply wishes to make yeast for his own con- sumption. Being desirous of giving as accurate an account as possible of the most advanced and scientific methods of manufacturing compressed distillers’ yeast for bakers’ purposes, the authors put themselves in communication with the directors of the Netherlands Yeast and Spirit Manufactory of Delft, Holland. In response they received an invitation to visit the factory and personally inspect the processes of manufacture. The following de- scription is compiled from information thus gained, supplemented by data furnished for the purpose by the directors of the factory. The operations of yeast manufacture resolve themselves into four groups w’hich may be classified under the following heads : — 1. Treatment of the raw grain, including the malting of barley. 2. Mashing and preparation of the wort. 3. Fermentation. 4. Collection and packing of the yeast. (1) Treatment of the raw grain. The grain required is brought by barge and directly discharged by elevators into granaries provided for that pur- pose. For yeast and spirit manufacture, there must be a sufficiency of appropriate protein matter, and also of carbohydrates. Brewing sugars are inadmissible, because by unduly reducing the proportion of protein matter, they w^ould cause the production of an unhealthy and weak yeast. The cereals most commonly used are barley, rye, and maize. Rice is not well fitted for yeast production, because of its comparatively non-nitrogenous character. The grain on arrival is first subjected to such cleaning opera- tions as may be necessary, including gravity separations of lighter and heavier foreign matter, and then a thorough washing. The cleaned grain is next conveyed to the mill, where the rye and maize are reduced to a moderately fine meal by roller mills. The barley is first converted into malt. In order to effect this object, two separate systems are in use. Ordinary Malting System. On this, known also as the old system, the barley is first soaked in water of a suitable temperature in large tanks. When sufficiently moistened, which operation may take from fifty to sixty hours, the grain is transferred to the malting floors and there allowed to germinate or sprout. As previously explained, this treatment destroys the parenchymatous cell-walls, and thus renders the interior of the grain more readily amenable to diastatic action. At the same time diastase itself is developed, and the nitrogenous matter rendered more soluble. 236 THE TECHNOLOGY OF BREAD-MAKING. When germination has proceeded sufficiently far, the malt is dried in kilns. The malt kilns are conical buildings in which the grain is laid on perforated plates. At the base the source of heat is fixed and consists of a species of grate in which the fuel is consumed. By means of a fan placed at the top of the kiln, a current of air is continually drawn through the grain, which is thus effectually dried. Pneumatic Mailings. On this system the malt floors are replaced by revolving drums, which are charged with barley. Air saturated with water is led into the drums and thus moistens the grain. Germination proceeds under efficient control, and when it has proceeded sufficiently far, the malt is conveyed to kiln-drums and there dried by means of heated air. Whether prepared by the old or floor-system, or pneumatically, the finished malt is ground to meal. (2) Mashing and 'preparation of the Wort. The meal of the raw grains, maize and rye, is treated by boiling with water in large boilers by the action of high pressure steam. When thoroughly cooked the mixture of grain and water is cooled and passed into the saccharification tuns, where the malt is added. Mashing then proceeds until the hydrolysis of the whole of the carbohydrates to maltose is as complete as possible. While the brewer finds it advantageous to retain dextrin and some amount of malto- dextrins in his wort, the distiller has practically no use for anything except the maltose, and so pushes the enzymic action to its utmost limit. At the close of the mashing the wort requires to be reduced to the fermenting temperature. It is important that this be effected as rapidly as possible, as the intermediate cooling stage is one at which the wort is most sus- ceptible to disease fermentation. For this purpose, refrigerators are em- ployed, of which there are several patterns. One of the most convenient is that originally devised by Lawrence, in which a copper pipe is bent again and again on itseK so as to form a vertical rack, with connected horizontal pipes in a series one over the other. Cold water passes through the pipe, and the wort is allowed to flow over the outer surface, thus being rapidly cooled and at the same time aerated. The cooled wort is then conveyed to the fermentation vats, where it awaits the next stage in the process of manufacture. (3) Fermentation. Of late years, the necessity of starting fermentation with a pure yeast culture has been more and more fully recognised. As explained in a previous chapter, paragraph 330, certain races of yeast are specially adapted for dough fermentation. For the preparation of these a specially equipped chemical and biological laboratory is provided. By appropriate methods, such yeasts are cultivated from a single cell until an appreciable quantity is obtained. In larger apparatus constructed on the principle of the Pasteur flask, a more abundant growth of the pure yeast is obtained, and this is used in starting the fermentation of the wort. The finished yeast is similarly controlled by tests as to purity and strength made in the laboratory ; and as occasion arises, the pitching yeasts are reinforced by addition or substitution of new pure culture yeast. The firm employs two distinct methods of fermentation, known respectively as the “ Vienna and the “ Aerating systems. Vienna System. The first step in this system is the preparation of what, in the bakers’ phraseology, may be termed a “ ferment,” that is, a pre- liminary fermentation of a relatively small proportion of the grain. Malt and rye are taken together for this purpose, and mashed at a convenient temperature, so as to obtain as complete a transformation as possible of the starch into maltose. The mash thus produced is alloAved to stand in the tubs at a temperature most suitable for the production of lactic acid, that is about 35° C. The lactic acid germs on the skin of the malt rapidly MANUFACTURE OF YEASTS. 237 develop, and a marked acidulation ensues. This is a most interesting step in the fermentation, and while the immediate result is the production of lactic acid, yet its ultimate effect is the prevention of development of the lactic acid ferment. This organism is peculiarly sensitive to the effect of its own product, and as little as 0*15 per cent, of lactic acid added to a mash is sufficient to prevent lactic fermentation taking place, although, on the contrary, if lactic fermentation be once started, it will proceed until something like 1 *5 per cent, of lactic acid has been formed. The reason of this inhibitory effect is that the addition of lactic acid is a deterrent not only to lactic fermentation, but also to the multiplication of lactic acid hacteria, so that, by its addition in the earlier stage, any reproduction of these organisms, and consequently any but the smallest possible produc- tion of lactic acid, is prevented. This first development of lactic acid, then, in what may be for convenience called the “ ferment,'' serves to check undue development of acidity in the main fermentation. It also further serves the useful purpose of peptonising and otherwise breaking down the nitrogenous matter of the grains in the mash, so as to render them available as yeast foods. The unfiltered wort, containing the “ grains " or husks of the malt and the raw grains, is treated at the desired temperature with pitching yeast in the form of the ferment already described. Air is driven through the wort by mechanical means in order to secure thorough aeration, and this operation is repeated from time to time as fermentation proceeds, as found necessary. The grains contained in the mash rise to the surface and there act as a non-conductor of heat. In from three to four hours after pitching, the carbon dioxide forces itseK up in a sort of cauliflower head through the grains and “ breaks." The grains are removed by a skimming operation, and fermentation is allowed to continue for from ten till twelve hours from the commencement, and then the process of skimming off the yeast is commenced. The skimming is effected by means of a long arm which sweeps right round the vat and collects the yeast from the top into an inverted cone, which from its shape is called a parachute. The alcohol from the fermentation remains in the wort, which liquid is distilled, and the alcohol thus obtained in a concentrated form. The residual liquid, together with insoluble matter consisting principally of fibre from the grains, is prepared for, and used as, cattle-food. The fol- lowing figure. No. 23, shows diagrammatically the “ Vienna " method of yeast manufacture. Barge Jlo Rye, Maize Barley Maltings ■Mill- Wort Fermentation I Yeast, Spirit Wash Carbon cleansed, by (cattle- dioxide washed, distillation. food). in air. pressed. Fig. 23. — Vienna System of Yeast Making. 238 THE TECHNOLOGY OF BHEAD-MAKING. Aerating System. By this method, the wort is filtered from the grains before fermentation. The pitching or starting yeast is added to the clear wort, through which a strong current of air is forced. The yeast as pro- duced does not rise to the surface of the fermenting wort, but sinks and forms a deposit on* the bottom of the vats or tuns. At the close of the fermentation, the supernatant clear liquid contains the alcohol, and is removed for purposes of distillation. The residual liquid, together with the filtered grains, is prepared for use as cattle-food. The course of the various operations of the ‘‘ aerated system is shown diagrammatically in Fig. 24. Wort I Filtration Residue Fermentation of filtered wort with supply of air Deposit Clear liquid from Carbon of which through dioxide yeast. distillation in air. \ Alcohol. Clear liquid wash Wash (cattle-food). ^ Fig. 24. — Aerated System of Yeast-Making. (4) Collection of the Yeast. The yeast, whether skimmed on the old system or deposited on the new, has to be cleansed. For this purpose it is mixed with water and passed through a series of sieves (20 holes to the square millimetre). The sieves retain any grains and allow the yeast to pass through. The yeast is then washed by decantation, and allowed to settle. Any minute particles which have passed through with the yeast, being lighter than w^ater, rise to the surface and are thus separated. The deposited yeast, still containing much water, is passed through centrifugal machines by which much of the water is removed. The thick yeasty liquid is next pumped into filtering presses and thus obtained in the familiar dry state. The yeast is now ready to be packed, and for the British market is filled into jute bags, which are mechanically pressed into block shape and finally branded with the name and description of the manufacturers. As thus prepared “ N.G. and S.F.'' yeast consists of pure yeast cells of a specially selected type. It is practically free from foreign or “ wild ” yeast and also from bacteria. The secrets of successful yeast manufacture are raw materials of the highest quality, absolute cleanliness during the whole process of manu- facture, and finally eternal vigilance. This last is the invariable price of excellence in yeast. Cleanliness of vessels is ensured by washing and scalding with live steam. As an additional precaution, all vats and tuns are periodically treated either with sulphurous acid or bisulphite of lime, both of which are absolutely harmless and most efficient antiseptics. All floors are kept clean by continual rinsings with water, the pathways con- sisting of raised planks, under which the Avater passes freely. In the yeast- cleansing rooms, Avhere, being in the quiescent stage, the risk of contamina- tion is greatest, the floors and walls are continually treated with solution of chloride of lime, thus most effectively destroying all disease germs. 8uch is in outline the process of manufacture employed in the production MANUFACTURE OF YEASTS. 239 of one of the most widely used and highest character yeasts imported from the continent into the United Kingdom. 392. Characteristics of Compressed Yeasts. — ^A good sample of com- pressed yeast has the following characteristics — it should be only very slightly moist, not sloppy to the touch ; the colour should be a creamy white ; when broken it should show a fine fracture ; when placed on the tongue it should melt readily in the mouth ; it should have an odour of apples, not like that of cheese ; neither should it have an acid odour or taste. Any cheesy odour shows that the yeast is stale, and that incipient decomposition has set in. Viewed under the microscope, compressed yeast consists of somewhat smaller and more oval cells than those of brewers’ yeast. In the best varieties are found no, or only traces of, foreign ferments ; other brands contain them in large numbers. The yeast cells themselves should possess the same characteristics as have already been described w^hile treating brew'ers’ yeast. A drawing of compressed yeast is given in Plate II. The cells were found, on measurement, to have the following dimensions — Longer diameter . . . . 10 mkms. = 0*0004 inch. Shorter diameter .. .. 7*6 mkms. = 0*0003 ,, Diameter of round cells . . . . 7*6 mkms. = 0*0003 ,, The sample in question was remarkably free from disease ferments, one only being seen in the field sketched, while several fields showed no foreign organisms whatever. The granulations show very distinctly. The yeast in question was a very pure one, and yielded exceedingly good results when subjected to strength tests. In general character, the compressed yeasts are steady and trustw^orthy in their action ; they produce sw^eet, well-flavoured breads, to wdiich, w4ien in good condition, they do not impart any yeasty taste. Their good qualities stand out most distinctly in summer time, w'hen other yeasts so frequently fail entirely to produce a satisfactory loaf of bread. Their being produced in such large quantity causes their manufacture to be entrusted to men who bring the highest skill that practical experience and science can furnish to bear on every detail of manufacturing processes. The many good properties of distillers’ compressed yeast have led to its almost universal employment where obtainable, in place of other kinds of yeast. 393. Admixture of Starch with Yeast. — It is a matter of history that in the earlier production of compressed yeast for commercial purposes starch w^as invariably used. This is simply following a common practice, for frequently in pharmaceutical and other preparations starch is employed as a drying agent : for this purpose it is w^ell adapted, being neutral in its qualities, inert and absolutely harmless. Yeast, containing bacteria, has a peculiar slimy nature and, therefore, cannot be pressed w^ell ; henee the addition of starch permits not only the more rapid, but also the more com- plete removal of water. With improvements in yeast manufaeture, the difficulty of pressing has been diminished, as purer yeasts are “ cleaner ” in the sense of freedom from external sliminess, and so filter more readily. With these improvements the previous difficulties have almost entirely disappeared, and the addition of starch can no longer be regarded as a neeessity in the manufaeture of compressed yeast. Although many, if not most, yeasts are now offered to buyers as consisting of pure yeast cells only, samples containing starch are still on the market. For this there are probably several reasons. It has been stated that eommercial yeast contains quantities of stareh varying from 5 to as much as 75 per cent. ; if this be so, evidently the wdiole of the larger amount is not added for the 240 THE TECHNOLOGY OF BREAD-MAKING. purpose of effecting more rapid filtration, but is an adulterant pure and simple. So far as smaller quantities are concerned, the authors’ opinion is that one and the same yeast, if mixed with a small quantity of starch,, has superior keeping powers to those it possessed when free from this ad- mixture, especially during hot weather. This conclusion is based on the- observation of samples of such yeast in the laboratory, and also on the testimony of bakers in provincial districts whose yeast is comparatively old when it reaches them, and then has to be kept some days. The presence of starch diminishes the moisture present, and this, no doubt, is the reason of its better keeping qualities. On the other hand it may be argued that modern high-class unmixed yeasts possess sufficiently good keeping qualities- to satisfy any ordinary requirements of commercial use. Briant states that “ordinary pressed yeast contains from 70 to 75 per cent, of moisture, and that if starch be introduced, the proportion present is considerably smaller, and, within certain limits, it can be shown that the starch only replaces a proportion of the moisture, and reduces that in the yeast itself, so that it is possible that the percentage of yeast may be even greater instead of smaller. The starch abstracts moisture from tho yeast cells themselves, so that it is possible that the addition of starch may increase the proportion of actual yeast in the ssmple, as shown by the following figures : — Sample. Yeast. starch. Moisture, Ash, etc. No. I 24-60 per cent. None per cent. 75-40 per cent. „ 2 . . 25-10 None ,, 74-90 „ 3 . . 26-15 5-70 68-15 ,, 4 . . 24-08 12-15 „ 63-77 „ 5 . . 20-50 17-20 „ 62-30 It will be seen that the yeasts containing starch are decidedly drier. In No. 3 sample it will be further seen that the percentage of starch intro- duced has actually increased the quantity of real yeast present, so that the purchaser, although buying a proportion of starch for yeast, would nevertheless obtain more yeast than he would have, had the sample been perfectly pure. . . . There is one direction in which the use of starch is really commendable, namely, by the reduction it effects in the percentage of moisture in the sample, and the consequent increased keeping quality imparted thereto. . . . The drier the yeast, the better it will keep, and it is in this sense that the use of starch in yeast may be of service to the baker.” The following determinations were made by one of the authors on two samples of the same manufacturer’s yeast, unmixed and mixed. Unmixed. Mixed. Starch 0*00 per cent. 19-20 per cent. Water 72-88 „ 60-40 The unmixed yeast therefore contained 12-48 per cent, more water tlian the mixed sample, which latter contained 19-20 per cent, of starch Of this starch, therefore, 12-48 per cent, simply replaced water, leaving a surplus of 6-72 per cent, of starch, which had gone to increase the weight. A test was made of the gas-evolving power of the two yeasts, with the result that the unmixed sample yielded 440, and the mixed sample 443 volumes of gas in four hours. Granted that small amounts of starch act beneficially, this is no justifica- tion of the addition of inordinately large quantities. In suggesting a limit, beyond which the presence of starch should be considered by the baker in the light of an adulterant, the maximum of 20 per cent, is suggested, wliich amount will usually, so far as the authors’ experience goes, coincide MANUFACTURE OF YEASTS. 241 with an actual increase of weight of the mixed yeast by about 8 per cent, over the weight of the same yeast if supplied pure. It goes without saying that the sale of a mixed yeast, as unmixed, constitutes a fraud on the pur- chaser. There is no reason in fact why the addition should not be declared, with an explanation that it serves to improve the keeping qualities of the yeast. In the case of James v. Jones, 1894, l.Q. B. 304, it was held that baking powder was not an article of food within the meaning of the Sale of Food and Drugs Act, 1875, and following this decision magistrates have held that it followed that as yeast belongs to the same category as baking powder, it is also excluded from the legal definition of food. No doubt as a result of this decision, the definition of food is extended as follows in section 26 of the Sale of Food and Drugs Act, 1899 : — “ For the purposes of the Sale of Food and Drugs Acts the expression “ food "" shall include every article used for food or drink by man^ other than drugs or water, and any article which ordinarily enters into or is used in the composition or [preparation of human food ; and shall also include flavouring matters and condiments."' Yeast and baking powder are now therefore both clearly articles of food within the meaning of Food and Drugs Acts. “Patent,” or Bakers’ Home-Made Yeasts. 394. As already explained, these are now largely replaced by com- pressed yeast. But there are still districts where this is unobtainable, and where bakers must perforce prepare their own yeast. It is hoped that these will find the following paragraphs of service. Bakers’ home-made yeasts may be divided into two varieties — malt and hop yeasts as used in England, and flour barms as employed in Scotland. 395. Bakers’ Malt and Hop Yeasts. — ^These consist essentially of small mashes of malt and hops, fermented either by the addition of some yeast from a previous brewing, or allowed to ferment spontaneously : the latter is known as “ virgin ” yeast. The hops present tend to prevent disease fermentations, as their bitter principle is inimical to bacterial growth and development. In virgin yeasts, particularly, it is necessary to use hops largely, and also plenty of malt ; as lactic and other foreign ferments flourish far better in a dilute saccharine medium than in a stronger one. The reader will already be familiar with the general outlines of the fermenta- tion of a hopped wort : as an introductory to directions for the preparation of patent yeast a careful study of the following experiment, made by one of the authors, will be of service. The student will do well to repeat the experiment for himself : sufficiently full directions are therefore given to enable him to do so. Take two quarts of water and half an ounce of good hops ; set these to i boil in a large glass flask or other clean vessel ; boil for half an hour, and I then cool down to 65° C. (149° F.). Scald out a large glass beaker, or » failmg this, a vessel of copper or enamelled ware ; wood will not answer I well. Weigh out 12 ounces of ground malt and mix with the hops and i water in the beaker. Maintain the whole at a temperature of from 65° to 70° C. (149° to 158° F.) for two hours ; this may be done by standing the beaker in a hot water-bath. By the end of this time the saccharification ; of the malt should be complete. Have ready another glass vessel perfectly p clean and scalded. Strain the wort, from the grains, through calico into p this second clean vessel ; cool down as rapidly as possible to 25° C. (77° F.). b In the meantime have ready a large water-bath, carefully regulated at a k' temperature of 25° C. by means of an automatic temperature regulator. 242 THE TECHNOLOGY OF BREAD-MAKING. Also thoroughly clean and scald six glass beakers of about 16 ounces capacity, and have ready glass covers for each beaker. Pour the filtered wort into these beakers, placing about an equal quantity in each. Label both beakers and cover with numbers from 1 to 6. Let No. 1 remain in the condition of plain wort ; to No. 2 add 1 gram (15 grains) of good brewers’ yeast ; to No. 3 add 0*7 gram (10 grains) of good compressed yeast. Prepare Nos. 4, 5, and 6 in exactly the same manner, so as to form a corresponding set. Cover each beaker with its glass cover and stand the whole in the water-bath. Let the first series remain undisturbed, but aerate those of the second by, some five or six times a day, pouring the contents of each beaker into a clean empty beaker, and then back again several times. After each aeration replace the covers and stand the beakers again in the bath. After about 24 hours examine each sample under the microscope. In the authors’ experiment. No. 1 at that time contained no yeast ; Fig. 25 represents its appearance after three days. This, and also several figures which follow, are simply facsimiles of rapid sketches made in a laboratory notebook. The most careful examination of field after field revealed not a single Fig. 25. — Malt Wort Allowed to Ferment Spontaneously. Left half of field taken from ferment; right from the same after being sown in warm “yeast mixture ” for about three hours. Magnified about 440 diameters. yeast cell, while the whole liquid was swarming with bacteria ; a slight frothy had formed on the top. The left hand side of the figure shows the wort ^ as taken from the beaker, one or two grains of starch being visible. A portion of this wort was then sown in Pasteur’s Fluid (Yeast Mixture), and again examined at the end of three hours, being maintained for that time at 26*6° C. (80° F.) ; its appearance is shown in the right hand portion of the figure. The student is recommended to employ a fermenting tem- perature of 25° C. This result was obtained not merely once, but also in a complete duplicate series of experiments. The mode of procedure is the same as that employed by those bakers who are in the habit of allowing their yeast to ferment spontaneously — except that chemically clean vessels are employed throughout. Another interesting point is that although yeast was being used in the room at the time, and even beakers, containing actively fermenting worts, were standing side by side in the same water- bath, yet the loosely fitting glass covers were sufficient to prevent the MANUFACTURE OF YEASTS. 243 entrance of yeast cells or spores into beaker No. 1 from external sources. Within twenty-four hours after being pitched, each sample was thus examined under the microsocpe. Nos. 2, 3, 5, and 6 were in a state of vigorous fermentation. Subjoined are sketches made in Nos. 5 and 6 respectively. Fig. 26 shows the yeast to be in an actively budding state. Notice that buds of different sizes, d, are attached to the various cells. The interior of the cells is free from granulations ; a few show, however, as for instance c, a distinct vacuole. In the centre of one group an old or parent cell, a, is seen. The irregular fragment marked 6 is a small piece of cellulose from the malt. r Fig. 26. — Brewers’ Yeast, 24 hours after being sown in Malt Wort. Magnified about 440 diameters. ' Fig. 27. — Compressed Yeast, 24 hours after being in Malt Wort. U Magnified about 440 diameters, " The appearance of Fig. 27 is very similar to that of the preceding one. An example of an old cell is to be seen toward the left, while the field gener- ally is occupied by new cells, perfectly free from granulation, and containing 244 THE TECHNOLOGY OF BREAD-MAKING. no vacuoles. In general aspect the cells are more ovoid in shape, and smaller, than those of the brewers’ yeast. At the end of three days the yeasts were again examined, having been maintained at a temperature of 26*6° C. (80° F.) for this time ; a sketch was then made of No. 2 sample of brewers’ yeast. Fig. 28. — Brewers’ Yeast, three days after being sown in ]\Ialt Wort. Magnified about 440 diameters. After this lapse of time the fermentation had very nearly ceased. Instead of observing a field covered with perfectly new cells, the majority of which were actively budding, the aspect of the yeast is far more quiescent. Here and there an old cell is still to be seen, as at a. The new cells, however, have begun to assume somewhat the same appearance. In some of them vacuoles are to be seen, but only in a few. The sketch does not faithfully represent the appearance of tlie vacuoles, as these really only appear as lighter parts of the cells, and are not circumscribed with a dark line, such as one has to use in sketching them in these figures. All the cells are more or less filled with faint, but distinct, granulations. Fig. 29. — Compressed Yeast, throe days after being sown in Malt Wort. Magnified about 440 diameters. MANUFACTURE OF YEASTS. 245 There is at the end of this time a marked difference in appearance between the pressed as compared with the brew^ers' yeast. The vacuoles show much more distinctly, so also the interiors of the cells are much darker ; the sketch shows several of parent cells, as at a, a. Particular attention is drawn to the fact that whereas samples Nos. 1 and 4, which were allowed to ferment spontaneously, swarmed, after three days, with 'bacteria ; the whole of the other four specimens which had been sown with yeast showed, on observation, no foreign ferments what- ever. It is possible that some may have been discovered by careful and systematic examination, but the main point is that, compared with Nos. 1 and 4, they were to all intents absent. Now, save by the addition of yeast, all the samples were exposed to precisely the same conditions ; the only conclusion to be drawn is that the presence of yeast growth is more or less inimical to that of foreign or disease ferments. The practical lesson to be learned from this is that bakers who prepare their own malt and hop yeasts, by sowing them with small quantities of pure yeast, not only induce a healthy growth of pure yeast ferments, but also retard the growth and development of disease ferments. The most probable explanation of this lies in the fact that, under the conditions of the experiment, there is a more or less acute struggle for existence betv/een the two organisms, and yeast, being the more vigorous and hardy, grows and develops at the expense of the bacteria. (Compare with the views advanced in paragraph 378.) After standing some time the vessels of yeast were covered with a film of Mycoderma cerevisice ; a growth which has been described in Chapter IX., and illustrated in Fig. 15. Nothing has as yet been said about the difference between the series of beakers that were allowed to remain undisturbed, and those which were aerated from time to time. Before doing so it would be well to describe the results of determining the amounts of gas evolved by the respective samples on being tested in the yeast apparatus. At the time these experi- ments were made, the older form of apparatus was employed, in which the gas bubbled up through the water. After standing three days these samples of yeast were tested by being inserted in the testing apparatus. Half an ounce of yeast mixture was taken, to this was added six ounces of the thoroughly stirred yeast. At the end of three hours the following quantities of gas were found to have been evolved from each : — Cubic Inches. No. I. Spontaneous ferment, undisturbed . . . . 3*1 No. 2. Pitched with brewers’ yeast, undisturbed . . 16*8 No. 3. Pitched with pressed yeast, undisturbed . . 35*6 No. 4. Spontaneous ferment, agitated . . . . . . 3*7 No. 5. Pitched with brewers’ yeast, agitated . . . . 18*6 No. 6. Pitched with pressed yeast, agitated . . . . 42*8 The experiment shows very clearly that the agitation has resulted in the yeast being in every instance more vigorous in action. In the ease of the spontaneous ferment there was a distinct, though slow, evolution of gas. The samples pitched with the pressed yeast had, by the bye, more than twice the capacity for causing the evolution of gas than had those which were pitched with brewers’ yeast. It is plain that agitation in some way increases the vigour of yeast. Those students who have earefully read the section of Chapter IX., dealing with the influence of oxygen on fermentation, will clearly understand the eause of such increase in fermenta- tive power. When yeast is being made by bakers from malt and hops, although 246 THE TECHNOLOGY OF BREAD-MAKING. fermentation goes on, it is not the fermentation, as such, that is wanted. The change required is not the production of beer, but the growth and development of yeast ; hence the operation should be so conducted as to induce the greatest yield of yeast in the most active and vigorous form. Aeration, or “ rousing,"" as it is often termed, is, as will now be well under- stood, of considerable service. In brewing large quantities of yeast, it would obviously be difficult to aerate by pouring from vessel to vessel ; the same object may be served by from time to time thoroughly stirring the fermenting yeast. This free access of air not only stimulates the growth of yeast, but in addition is inimical to the development of disease ferments ; so much so, that by careful working with plenty of air a yeast can be made to give moderately good results, that would be absolutely unusable if fer- mentation were conducted in closed vessels. It follows that yeast is better brewed in comparatively shallow and open tubs than in deep and closed ones. The careful performance throughout of this experiment will not only be~an instructive exercise on fermentation, but will also afford good practice with the microscope. 396. Formula for Manufacture of Malt and Hops Patent Yeast. — The following formula for the manufacture of patent yeast is taken from “ The Miller,"" — 40 gallons of water and 2 lbs. of sound hops are boiled together for half an hour in a copper, and then passed over a refrigerator, and thus cooled to a temperature of 71° C. (160°F.). The liquor passes from the refrigerator to a stout tub ; IJ bushels (about 63 lbs.) of crushed malt are then added, and the mixture thoroughly stirred. The mash is allowed to stand at that temperature for IJ hours, filtered from the grains, and then rapidly cooled to 21° C. (70° F.) The passage over the refrigerator serves also to thoroughly aerate the wort. Spontaneous fermentation is then allowed to set in, and the yeast is usually ready for use in 24 hours, but is in better condition at the end of two days. All fermenting tubs, and other vessels and implements used, are kept clean by being from time to time thoroughly scalded out with live steam. The result is the production of a yeast of very high quality. Or fermentation ^may be started by the addition of a small quantity of good yeast. 397. Suggestions on Yeast Brewing ; what to do, and what to avoid.— The quantities given above are larger than those required by many bakers, but the formula may be adopted for smaller brewings by taking a half, or quarter, or some other proportion of each ingredient. In connection with brewing, the first consideration is the room ; this should not be in the same part of the bakehouse as the ovens. Select, if possible, a room having an equable temperature of from 65 to 70° F. Stout tubs of appro- 2 >riate size should be used for brewing ; these should be about the same w'idth as depth. Before commencing, clean all tubs and implements with boiling water. The hops are better boiled in a copper ; iron vessels are apt to discolour them, especially if the vessels are in the slightest degree rusty. Let the hop liquor cool down to the temperature given, before adding the malt, as a temperature much higher than from 65 to 70° C. destroys the diastatic power. On no account boil the malt : some bakers place malt and hops together, and boil the two, under a mistaken idea that 'they get more extract from the malt. The result is that diastasis is arrested long before the whole of the starch is converted into dextrin and maltose. For the same reason, fifteen minutes is too short a time for the mashing to be continued. The baker not only requires to saccharify his malt, but it is also necessary for him to convert as large a proportion as possible of his dextrin into maltose. This is hindered either by using; MANUFACTURE OF YEASTS. 247 too high a temperature, or mashing for too short a time. Starting with a mashing liquor at 65 to 70° C., and mashing for from IJ to 2 hours, gives about the best results. The cooling after removal from the grains, which may be washed or “ sparged "" with a small quantity more water, must be done quickly, so to as have the wort for as short a time as possible at a temperature of from 35 to 40° C., as at that temperature bacterial fer- mentations proceed most vigorously. The wort at 21 *5° C. (70° F.) may either be pitched with a small quantity of yeast reserved from the last brewing, or by the addition of a small quantity of good fresh compressed yeast. If wished, the fermentation may be allowed to set in spontaneously, as suggested in the preceding paragraph, in which case a “ virgin "" yeast is produced. It is doubtful, however, whether this is to be recommended in most cases. The risk of spoiled yeast is greater, and at times alcoholic fermentation does not set in at all, or too late to prevent its being preceded by excessive lactic and other foreign fermentations. The temperature should not be allowed to rise, during fermentation, much above 21 to 22° C. In summer time there is a great tendency for a rapid rise to set in ; this may be controlled by placing an attemperator in the wort, and passing a stream of cold water through. An attemperator consists of a properly arranged series of pipes, through which hot or cold water at will may be passed. Temperatures must in all cases be got right by actual use of the thermometer. From time to time, stir the fermenting wort so as to rouse or aerate it. When the yeast is made, keep it freely exposed to air. In making patent yeast it is very poor economy to stint either malt or hops : a weak wort produces a much less healthy and vigorous yeast than does a strong one, beside being much more subject to disease fermentation, and eonsequent acidity. And, when made, the dilute yeast shows no saving, because so much more of it has to be taken in order to do the same work. 398. Specific Gravity of Worts, and Attenuation. — ^In addition to taking the temperature of his worts, the brewer also tests the density or specific gravity of each sample. This is done as a means of estimating the amount of soluble extract obtained from the malt. The maltose and other soluble carbohydrates, yielded on mashing, increase the specific gravity of the wort. Taking the density of water as 1000, each gram of carbohydrate in 100 C.C., or, what amounts to the same thing, each lb. of carbohydrate in 10 gallons of the wortincreasesthedensity of the solution by 3*85. Thus, suppose that a wort is found at 15*5° C. (60° F.) to have a specific gravity of 1011*5, then 1011*5 - 1000 3*85 = 3 = weight in lbs. of sugar and other solid matter in 10 gallons of the clear wort. As the density of a liquid varies with its temperature, all densities are best taken at the uniform temperature of 15*5° C. The Inland Revenue Act of 1880 assumes that 2 bushels of average malt, weighing 84 lbs., will produce a barrel (36 gallons) of wort having a density of 1057. Accepting this estimate as correct, and assuming that the 40 gallons of water employed in the previously given recipe, together with the small extra quantity used in sparging or washing the grains, yield after loss through evaporation 40 gallons of wort ; then the wort produced ought to have a density of 1038*3, which is equal to almost exactly 10 lbs. of solid extract per 10 gallons of wort. Working with comparatively imperfect methods, and in small quantities, the baker cannot expect his malt to yield the full extract, but as a matter of practice he ought at any rate to get nothing less than a density of 1030. One of the most important sources of loss arises from imperfect sparging of the grains ; these should 248 THE TECHNOLOGY OF BREAD-MAKING be washed once, and may then with economy be put into a small press and squeezed dry. Of course, if with extra washing water the volume of the wort is increased, then the density will naturally fall. Testing the density of his wort is not only of importance to the baker, as a measure of the degree of efficiency with which he is extracting the valuable matters of his malt, but is also a test, of the highest value, of the regularity of his work. If one day a wort of comparatively high density is being attained, and on another one of low density, something is wrong, and must be righted. The baker should always endeavour to have his worts at the same density when ready for pitching : 1030 may be taken as a very good standard to work at. If it is found in practice that the densities fall below this, mash with comparatively less water ; if the densities run too high, dilute the wort with water until of the right density before pitching. The neces- sary quantity of water to add may be easily calculated, on remembering that the volume of the wort is in inverse proportion to the density, less 1000. Thus, supposing that the 40 gallons of wort are found to have a density of 1035, then as 30 : 35 : : 40 : 46 gallons. The wort will have to be made up to 46 gallons, therefore 6 gallons of water must be added. The quantity of wort produced should always be mea- sured ; to do this, determine once for all the capacity of the fermenting tubs in the following manner : — Prepare a staff about an inch square ; pour water into the tub, gallon by gallon, and at each addition put in the staff and mark on it the height of the water. This operation once com- pleted, the quantity of wort made can at any time be determined simply by plunging the staff into the tub and reading off the number of gallons as marked on it. For practical purposes, the density of a wort is best determined by a hydrometer ; this instrument is made either of brass or glass. It has a weighted bulb at the bottom, and a long graduated stem ; accompanying the hydrometer is a tall glass jar, known as a hydrometer jar. Fill this jar with wort at the right temperature, and place in the hydrometer ; as soon as it comes to rest, read off the graduation which coincides with the level of the liquid ; the number gives the density. For the baker, the most convenient hydrometer is one graduated in single degrees, from 1000 to 1040. The hydrometer is also sometimes known as a saccharometer. As fermentation proceeds, the density of the liquid becomes less, and at the same time it loses its sirupy consistency — hence the brewer states it to have become “ attenuated.'' 399. Microscopic Sketches of Patent Yeast. — In Plate II. are given microscopic sketches made of patent yeasts collected in the South of England. The sketches marked respectively a and h were drawn from samples of patent yeast, both obtained in the same town, but from different bakers, during the summer. The sample marked a was evidently prepared in a strong wort ; in fact, at the time of examination the yeast was still sweet through presence of maltose in considerable quantity, and had a high density. The yeast was not free from disease ferments, but still compared remarkably favourably in this respect with all other samples examined. One specially noticeable point about the sample was the elongated shape of the cells ; some were not merely ovoid, but even decidedly pear-shaped. One sketched shows this peculiarity in a very marked manner. This yeast was at the time yielding very good results ; the bread was sweet and of good flavour. One is in doubt with regard to sample h, whether it should be viewed as an example of alcoholic or bacterial fermentation ; certainly the latter ferments are about as plentiful as yeast cells. The yeast con- MANUFACTURE OF YEASTS. 249 tained very little either of maltose or hops ; in fact, it had evidently been brewed with as little as possible of these ingredients employed. Readers will probably not be surprised that yeast a produced a far superior loaf of bread than did yeast h. The sample c is likewise of considerable interest ; it was also taken during the summer. The baker was in the habit of, at the close of his yeast brewing, setting aside a portion for the purpose of pitching his next lot of wort. This pitching yeast was stored in a corked bottle. This also was a yeast brewed in a poor wort, although not so bad as sample h. Notice particularly, in c, the chain of elongated cells ; these are often noticed in yeast grown without sufficient aliment, and the sketch sliows a striking example. Scotch Flour Barms. 400. Flour Barms, Thoms’ Formulae. — The following descriptions of Scotch Flour Barms are from the pen of the late Mr. Thoms of Alyth, a well-known authority on Bread-making. Although WTitten some time ago, they describe very closely the methods still in use in Scotland : — “ There are many kinds of flour barms used in Scotland, in fact all are flour barms ; but for the present I will treat of two of the latest and best. These are ‘ Parisian Barm ’ and ‘ Virgin Barm.’ Virgin differs from Parisian only in being spontaneously or self-fermented. Parisian barm was introduced from Paris to Scotland, by a baker near Edinburgh, about the year 1865. It is essentially a leavening ferment ; a scientiflc modiflcation of the systems of ancient Egypt and present France. After its introduction to Scotland its use spread rapidly, and it alone is used in all the machine bread factories there, and in a number of the best estab- lishments in the north of Ireland. The Parisian is easier to make, but easier to spoil. All that is required is skiU to select the materials, and knowledge, founded on experience, to guide the process of fermentation, which results in inert flour and water, and infusions of malt and hops, being converted into the vital, seff-propagating and carbonic acid producing substance we call barm, which makes fermented bread light and vesiculated.” 401. “ Virgin Barm : Things Required. — ^A 30 or 32 gallon tub ; a small tub or vessel for malt-mashing ; 10 lbs. malt ; 3 oz. hops, and a jar in which to infuse them ; about 40 lbs. flour, of which one-third should be American Spring straight and two-thirds Talavera wheat flour, or sound red Winter ; 2 or 3 oz. salt ; 8 or 12 oz. sugar ; a handful of flour ; and about 18 gallons of boiling water. (The gallon here means the Imperial, holding 10 lbs. water at a temperature of 60° F.) 402. “ How to Use or Manipulate them. — ^Mash the malt for 1 J hours in 3 gallons of water after it has been cooled to 160° F. ; infuse the hops the same time in 1 gallon of water poured over the hops at a boiling tem- perature ; then strain the malt and hop infusions into the barm tub : now sparge or wash the draining malt grains with another gallon of water at a temperature of 190° or 200° F. Note, the malt grains are not pressed in any way, only allowed to drain. When the water has about stopped running from the grains, the liquor in the tub should show a temperature of 140° -146° F., then well and thoroughly mix in the flour with the hands. The next stage is scalding this mixture or thin batter with 7 gallons of boiling water, and stirring sharply with a stick. Begin by pouring in 2 gallons, and stirring it well up and from the bottom and all round, then add another 3 gallons and give more and sharp stirring, and finish with another 2 gallons and more stick work. The scalded batter is then a thick jellyish paste. The water used in malt and hop infusions and sparging is 5 gallons, in 250 THE TECHNOLOGY OF BREAD-MAKING. scalding 7 gallons, making in all 12 gallons. I mentioned 18 gallons because it is desirable to have more boiling water than required. 403. “ Fermentation. — ^The barm tub and contents are left in the brew- house uncovered for 21 hours or so. During that time the mixture under- goes several changes. The scalding water bursts a proportion of the starch granules of the flour, converting them into starch paste : the diastase of the malt inverts or hydrates this paste into a sugar, maltose, and a brown^ gummy body, dextrin. The mixture, after scalding, tastes very sweet ; in half an hour after it is sweeter, and thinner, and browner. These changes continue for several hours, then a distinct acid taste is felt. At the end of 21 hours the mixture is strained from one tub into another, so as to aerate it. When it has cooled down to 84° F., mix in the salt, sugar, and a handful of flour, and keep the tub lightly covered, or uncovered, in a place where the now slightly fermenting mixture will not fall below a tem- perature of 80° F., or rise over 84° F. Supposing this is done 24 hours after brewing, then during the next 24 hours stir up the mixture three times — the number of times depends on the fermentation being free or sluggish — and note the heat, and at the end of the 24 hours again strain gently from one tub to another. In another 12 hours stir up again ; it will then be in vigorous fermentation, and will rise and then fall. When nearly full dowm, or when a lighted match will burn within three or four inches of the surface, remove the tub to a cool place. This will be on the third day after brewing. This barm could be used in a sponge the same day, but it is far better on the fourth and fifth day after brewing. 404. “ Parisian Barm. — ^The materials, and quantities and manipulation, are the same as for Virgin. Only in about 24 or 27 hours after brewing, and when the mixture has cooled dowm to 84°-86° F. in winter, and 76°- 78° F. in summer, instead of putting in salt, sugar, and flour, and letting it self -ferment, it is stored or set aw^ay, with, in winter, about IJ gallons old barm, or Virgin ; in summer, about 1 gallon ; and the tub is best kept uncovered during and after fermentation, wiiere the temperature is be- tween 60° F. and 70° F. In this case active fermentation is about over in 16 to 24 hours, wiien it is better to remove the tub to a cooler place. With this barm, as with Virgin, and every other yeast, it is not advisable to use it in sponge immediately or shortly after it has dropped. They should be left undisturbed in a cool place at a temperature betw^een 40° F. and 60° F. Barm at this stage should be kept in shallow^ tubs, or coolers, where a large surface is exposed to free oxygen.'' 405. Microscopic Character. — ^View^ed under the microscope, Scotch flour barms ahvays show^ a certain proportion of lactic ferments as a nor- mal constituent. Thoms argues that their presence is beneficial, and states, in favour of that view, that when he has taken steps for brewing barm in w'hich lactic ferments are absent, that the bread is of inferior quality. The probable function of lactic ferments during panification will be dealt w'itli in a future cliapter. Scotch bread has always a slight acid flavour, totally distinct from wFat is understood in England as “ sourness " of bread, but more resembling in type the flavour of buttermilk. It should be exj^lained that this peculiarity is not quoted as a fault : in fact, those accustomed to bread of tliis flavour find something lacking if the acidity be absent. 406. Parisian Barm, Montgomerie. — On the occasion of the writing of the present edition of this work Mr. J. Montgomerie, of Glasgow, furnished the authors wdth the follow ing account of the manufacture of Parisian barm as now' conducted in Scotland. MANUFACTURE OF YEASTS. 251 “ Sixteen Scotch pints (of two Imperial quarts each) of water at 164° F. are mashed with 24 lbs. of crushed malt for from to 4 hours, stand- ing in a warm place so as to ensure as little loss of temperature as possible. It is then transferred to a malt press, and the wort drawn off. The wort, with the exception of 3 pints, is put in the tub, and 3 pints of water added at a temperature to bring it up to 120° F. (You have 13 pints of wort and 3 pints of water, making 1 J lbs. malt to the pint of water). Put in 112 lbs. flour. A good barm flour is a blend of flour obtained from spring and winter wheats in about equal proportions. The wort and flour are then stirred into a batter. Forty pints of boiling water are then stirred in, 4 pints at a time. The starch in the flour will gelatinise at the thirty- second pint. The last 8 pints are added when it begins to liquefy. The 3 pints of wort are then added. To take off a scald with a 4 pint mash, the temperature of the wort is 140 degrees F. 6 55 55 55 134 55 8 55 55 55 132 55 10 55 55 55 130 55 12 55 55 55 126 55 14 55 5 5 55 124 55 16 55 55 120 55 20 55 55 55 120 55 24 55 55 55 120 55 30 55 55 55 116 55 35 55 55 5 5 110 55 40 55 55 100 % s The last is the biggest taken off in any factory. “ The scald is then cooled until the temperature drops to between 80 and 90° F. in winter, and 60 and 70° F. in summer. If the Barm Cellar is kept at a constant temperature of, say, 56° F., then 80° F. is a very good temperature to scald at. “ Storing the Scald. Take the temperature of the scald and add 13 pints of matured barm as a store, ^.e., 1 pint of barm to 4 pints of scald. (As may be gathered from the preceding description, the “ store ” is a portion of old barm added for the purpose of pitching, or starting fermentation.) Allow it to lie for 3 or 4 hours, then divide into two or three suitable vessels and remove to the Barm Cellar, which should be large and airy, to ferment. The barm will come up its height in 18 hours, and then gradually settle down with a clear round bell on the top on the second day of fermenting. On the third day it will begin to clear off, and on the fourth will be cleared off. The barm is now ready for using, but most bakers prefer to allow it to mature to the fifth day, as it gives a better flavoured loaf, and the fermentation of the dough is more easily controlled. In the event of the barm showdng signs of hardness, decrease the quantity of malt used at mashing, and if of greenness, increase the quantity of malt. “ To keep barm right, it is essential that everything should be kept scrupulously clean, with a plentiful supply of fresh air, and that the barm be stored and kept at a constant temperature."^ 407. Scottish Barms, Meikle. — ^Mr. J. Meikle, the well-known baker and teacher of bread-making classes in Belfast, has read through the de- scriptions of Scottish methods given on the authority of Thoms in the older edition of this work, and has supplied the following addendum thereto for which the authors express their acknowledgments and thanks. The various data were submitted by Mr. Meikle to a number of bakers in Scotland, and may therefore be taken as thoroughly reliable in every way. 252 THE TECHNOLOGY OF BREAD-MAKING. Compound Barm. 40 lbs. Water. 10 lbs. Malt. 4 lbs. Store. 4 oz. Hops. 2 oz. Salt. Mash 3 hours. “ Compound Barm is not now used to the extent it was at onetime, but many of ithe older bakers agree that it is the barm for flavour in bread. Take 10 lbs. of water and mix in the hops, bring the water to the boil and allow to simmer for a few minutes. Transfer this to a 5 gallon tub and add 30 lbs. of water at 180° F. to make up to 40 lbs. Throw a flour bag over the tub and allow the liquor to cool to 164° F., then stir in the malt, cover up the tub well, and keep it in a warm corner for about three hours. At the end of that time run the ‘ mash " into a barm press and press out all the liquor. Cool this as quickly as possible to 72° F., stir in the store and the salt, then set the whole to ferment for 36 hours. At the end of that time the gas should all be gone ; it should in fact have ceased to hiss : if hissing still goes on the barm must not be used as it is not ready. Some Scotch bakers will not touch this barm until hissing ceases, but a good rousing stir will help matters considerably. “I have used pounds in connection with liquor, and will use this system in what follows for the reason that the Scotch ‘ pint " does not always mean a definite quantity. It generally means half an Imperial gallon, but often it means a real old Scotch pint, which is equal to about 3 Imperial pints or almost 4 lbs. avoirdupois. An Imperial gallon of water weighs 10 lbs. avoirdupois, so that the figures given divided by 5 give the number of Scotch pints (half gallons) as generally in use, and divided by 4 give old Scotch pints. Virgin Barm. 20 lbs. Water at 125° F. 32 lbs. Flour. 45 lbs. Water at 212° F. 10 lbs. Store. “To lie 12 hours before ‘Storing,’ or till it falls to 80° F. ; 60 hours afterwards it will be ready. “ Mix the water at 125° F. with the flour into a stiff paste by hand, making sure that boiling water is immediately afterwards available. Scrape down the batter in the inside of the tub, then add boiling water 2 pints at a- time (a gallon) stirring vigorously between each addition with a stick of the nature of a broom handle. The mixture will be easy to stir at first, but when the starch cells begin to burst it will ‘ grip,’ and care must be taken, first, to keep clear of lumps, second, not to add too much water. Tlie strength of the final barm depends on the solids, not upon the amount of water added. The scald must now lie for about 12 hours, when it will have not only become cool, but also thin, and slightly tart (acid.) Now add the store and a handful of flour, stir well and allow to ferment for 56 liours.. Foaming will start at the sides and will gradually cover the top : if a ring still remains in the centre when the barm is to be used the baker must make up his mind for weak fermentation. Real Virgin Barm is not stored at all, but I have never seen such barm worked. Virgin, so called, has been gradually displaced by Parisian, but I have seen it used many years and have seen much good bread made from it. 253 MANUFACTURE OF YEASTS. Parisian Barm. 15 lbs. Water) , , ^ac\o^ 3f lbs. Malt 22 lbs. Flour. 35 lbs. Water at 212° F. 10 lbs. Store. ‘‘To lie 12 hours before storing or until it reaches 76° F. ; ready 50 hours afterwards. “This is the barm of Scotland to-day and is made as follows. Mash the malt and water as for compound barm ; that is measure the water in a clean tub at a temperature of about 180° F., cover this up and allow the temperature to fall to 162° F., then add the malt. The reason for using water at 180° F. is to ensure the tub being thoroughly warmed up : by well covering up after mashing the proper temperature is kept up for a longer period — the subsequent barm will be no good unless care is exercised at the very start. In two and a half hours wring off the liquor and add sufficient water at 150° F. to bring up the total to 15 lbs. and the temperature to 128° F., stir in the flour by hand, and afterwards add the boiling water, and stir vigorously as already described for Virgin barm. The scald should not be so stiff as for Virgin, and should taste sweet when newly made. It begins to thin almost immediately, and as it lies gets a little sharper in taste; it should not, however, be cooled artificially. When storing stir vigorously and well. Parisian barm while fermenting behaves like a thin ferment made with distillers^ yeast, sugar and a handful of flour, only the bells or gas bubbles are larger and brighter. The barm has the strength, with- out the “ rampness,'" of compound, and the mildness without the weakness of Virgin. Of suitable barm flours more further on. In the making of scalds in large places machinery has been utilised. The stirring machine is used with success in making large scalds in the factories, such scalds being afterwards divided amongst several tubs for fermenting purposes.'* {Personal Communication, October, 1910). CHAPTER XIII. PHYSICAL STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 408. Functions of the Wheat Grain. — ^The wheat grain is that part of the plant on which falls the task of performing the functions of reproduction, hence all its parts are specially adapted to that purpose. The germ, or embryo, of wheat, really the true seed, is that portion of the grain which ultimately develops into the future plant. The main body, composed principally of starchy matter, is termed the “ endosperm '' : its function is to supply the germ with food during the first stages of its growth. Besides these there are the various outer and other coverings, destined for the ade- quate protection of the seed, which together constitute the bran. The physical structure of the wheat grain requires for its systematic study the use of the microscope : the descriptions following therefore include practical directions for microscopic observation. The arrangement adopted is that most easily followed by the student in a course of actual microscopic work. For earlier studies it is well to obtain from the dealer ready-mounted longi- tudinal and vertical sections of a grain of wheat. In every case, practise sketching what is seen : as before stated, the accompanying figures are facsimiles of those which the student should himself make. 409. Longitudinal Section of Whole Grain. — In the first place, examine the longitudinal section of the grain of wheat with the 3-inch objective ; the whole of the grain will then be in the field. Try, in the next place, to make a sketch of it. For this purpose the student should use a camera lucida if he should possess one. Trace in the outline and other principal lines with a hard pencil ; then go over them with a lithographic pen and liquid Indian ink. It will be impossible to get in all the details ; the effort should be rather to show what is essential ; thus the object of the sketch with the low objective is to get an idea of the general shape and arrangement of the diferent constituent parts of the grain. When the drawing is complete, mark underneath the number of diameters to which it has been magnified. In Plate VI. is given a section through the crease of the grain, which is shown in elevation by shading on the left-hand side of the figure. The whole of the figure has been obtained by careful tracing in the authors' laboratory from typical slides, and is throughout a faithful representation of the grain. The germ is seen at the lower end of the figure, and a fair idea of its size, compared with that of the endosperm, which constitutes the remainder of the grain, may be obtained. Enclosing both germ and endo- sperm is the bran. With the low power, which the student has been directed to use, the square cells of the bran lining the interior, and known as aleurone cells, are just visible. The name commonly given to theseis, by the by, a misnomer ; they are not “ gluten " cells, for the reason that they contain no gluten. The more minute examination of the grain is best made by the aid of tlie liiglier powers, and sliows more of the details drawn in Plate VI., to which reference is made in the paragraphs which follow. The various parts of the grain are fully indicated on the plate itself. 254 Plate VI. Tlairs of J5,c^‘cl, CutCcLe, E/tCc/ir;z, Entio^-arfL Epfspjcmv, \ A^jCAzrone. ColLy } Bran. WarcA^Cef l Efllcxi. \uAthy yrrojzfj 7/^*5. e %rerfrJz^m/xtDtLS . 'UitlosG dimdfji^ C7idvs//er/?v/j7tb . Stcu'cTi. cgILs. ConyiresscA ompt^ (rf 'eJ7Ao.3prrm . Tcrmirta/yort' of 'I aZGurono c^7Ms ctZ lcoiiiiTtencent£77f of Germ. iAbsorpZiye ^ sec7'AX*f\ [op/ffr^ZCLi/rG'^ I P(AUTtula> SIviaXiL, I /SxMitellf/jrv, / J^Joi'igaCojdL cxdJs of A ^CAJLtC^UAAJIl^^ ^RcfoLinijCrr/cfrt/ cf JRmoivuXcju, ^ i^sCcz, crcco.CbiA.wu^ l^.nro,(opp enclosfrJjg 1 boTJzEtbclok^peyni \anfl Geonv. TLcuticle', Ttco.tJ Sfteceffb, EucHclCy Cafv E. Endosperm. G. Germ. Longitudimal Section through a Grain of Wheat. Ma^jn/fLcAi ayboLA aC dfxAjrictyCf''S . 256 THE TECHNOLOGY OF BREAD-MAKING. 410. Transverse Section of Wheat Grain. — Examine next a transverse section of a grain of wheat ; the section, below figured, Fig. 30, was cut from a grain of Kubanka wheat, and passes through the germ. Fig. 30. — Transverse Section of Grain of Wheat, magnified ISMiameters. On examining carefully such a section as that shown, the pigment-con- taining cells are seen in a line passing completely round the grain, and forming a thick spot of colour in the crease. Notice that the aleurone ceUs of the bran do not continue round the germ. Observe also as much as possible of the structure of the germ itself, and the relative dimensions and positions of germ and endosperm. Examine the same section in the next place with the 1-inch objective (Fig. 31). The outer skins of the bran are here seen more plainly ; the Fig. 31. — View of Crease in Grain or Wheat, as shown in a transverse section, magnified 110 diameters. square aleurone or cerealin cells are also plainly visible. Notice that near the bottom of the crease, the cells, instead of being in single line, are in double, becoming more numerous and irregularly arranged as the bottom is approached. The crease distinctly bifurcates at the bottom ; the pig- ment layer of the grain becomes considerably enlarged, and its section is seen at the middle of the fork as a dark yellow spot of considerable size. With this power the starch granules also become visible. STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 257 411. Section Cutting and Mounting. — It has been assumed that, for the purposes of making these studies and sketches, the student has had in his possession sections that he has purchased ready mounted. He will probably at this stage of his work wish to prepare and mount sections of his own. Wheat in its ordinary state is too brittle to permit of its being cut in thin sections. In the first place, therefore, soak a few grains in water for about twenty-four hours ; the water may be luke-warm, say at a temperature of 80° to 90° F. When the grains have become moderately soft, sections may be cut from one of them. For this purpose a very sharp razor, which has been ground fiat on one side, is generally used. Take one of the grains between the thumb and finger, cut off one end, and then proceed to slice off sections as thin as possible. Some little practice will be necessary before they can be successfully cut of the requisite thinness. This operation is rendered easier by the use of a section cutting table. This little piece of apparatus consists of a plate of brass, the surface of which has been turned perfectly plane ; in the centre is fixed a tube containing a piston, which may be raised by means of a screw. The object whose section it is wished to procure is first cast into a block of either cocoa butter or solid paraffin. In either case the temperature of these must only just be raised to the melting point. This block of solid paraffin or other substance is next trimmed down so as to go into the tube of the section cutting table. Adjust the screw at the bottom so that the grain is in about the right position, then draw the razor across the top of the tube and cut off the upper part of the grain ; screw up the piston at the bottom of the tube very slightly, and cut off a section by again drawing the razor across the plane surface of the table. In this manner thin sections may be cut with comparative ease. Having thus obtained the sections, wash them in a little spirits of wine and transfer to a slide. If it is only wished to examine them without this being pre- served, they may be mounted in a mixture of water and glycerin in equal volumes, protected with a cover slip, and at once placed under the micro- scope. When, however, it is wished to make a permanent mount, they may be embedded in glycerin jelly (Deane’s medium). Having washed and prepared a section, and also the slip and cover, place a very little of the gly- cerin jelly on the slide, warm very gently, and the jelly becomes liquid. Place the section carefully in the liquid medium, taking care that it is tho- roughly immersed. Remove all air bubbles, place on the cover as carefully as possible, gently squeeze out any superfluous medium, and allow to cool. The jelly will then again become solid. Clean the edge of the cover glass, and coat round with asphalt varnish. 412. The Germ. — The appearance and general characteristics of the germ itself should now be carefully studied ; for this purpose use the 1-inch objective. In Plate VI. the germ is shown very distinctly, and the whole of its parts named and indicated by reference marks. This should be carefully studied. Notice that the aleurone cells of the bran terminate at the junction of the endosperm and germ, and only the “ testa ” or envelope of the true seed encloses the embryo. The “ plumule ” is that part of the young plant which penetrates to the surface during growth, and then constitutes the growing stem and leaves of the plant. It consists of four rudimentary leaves en- closed within the plumule sheath. The radicle, or rootlet, on commencing its growth, forces its way downward into the earth. The germ constitutes about 2-0 per cent, of the whole grain, while its enclosing membrane is stated by Mege Mouries to amount to as much as 3-0 per cent. The nature of the other portions of the germ had best be described when dealing with their functions in connexion with the act of germination (para- graph 418). 258 THE TECHNOLOGY OF BREAD-MAKING. 413. Endosperm and Bran. — ^Attention must next be directed to the structure of the endosperm and the branny coatings by which it is enveloped. For this purpose a very thin section should be selected and then examined under the |-inch objective. The bran of wheat is divided into the outer envelopes of the grain and those of the seed proper. Following these in the order of the letters given in Fig. 32 : — a — is the outer “ epidermis/" or “ cuticle."" According to Mege Mouries this constitutes 0*5 per cent, by weight of the whole grain. h — is the “ epicarp/" and amounts to about 1*0 per cent, of the grain. c — is the last of the outer series of the envelopes of the grain, and is known as the “ endocarp."" It is remarkable for the well-defined round cells of which it is composed. The endocarp amounts to 1*5 per cent, of the grain. d — is the first of the envelopes of the seed proper ; it is that to which reference has already been made as the “ testa ""; it has also received the name of “ episperm."" The colouring matter of the bran occurs principally in the episperm. e — is a thin membrane lying underneath the testa, and enveloping the aleurone cells. This membrane and the testa together form 2 per cent, of the grain. / — is the layer of “ aleurone "" cells, so called from the protein of that name which they contain. As may be seen from the figure, the cells are Fig. 32. — Longitudinal Section through Bran and Portion of Endosperm OF Grain of Wheat, magnified 440 diameters. almost square in outline ; one is at times replaced by two lesser ones, as occurs immediately above the cell /. Notice particularly that this layer does, not envelop the germ, but only encloses the endosperm. g — represents the layer of parenchymatous cellulose by which the in- terior of the endosperm is divided up into a number of cells of comparatively large size, these in turn being filled with starch granules, and embedded in gluten. h — shows the “ hilum "" of an individual starch granule. STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 259 In order to complete the investigations of the appearance, when viewed under the microscope, of the various coatings of the wheat grain, it is not only necessary to examine these skins in section, but also, so far as possible, as seen on the flat. The bran of wheat can be split up with comparative ease into three layers, which can be successively peeled off from the endo- sperm. The first of these consists of the epidermis, or cuticle, and also epicarp. Following these are the endocarp and episperm, which usually peel off together. The inner and last skin consists of that containing the cerealin cells. Take a few grains of soft red wheat and soak them for a few hours in warm water ; when they are sufficiently softened, take one, and mth a fine pair of forceps strip off the outer skin and place it in a watch glass. When the whole of the outer skin has thus been removed, carefully strip off the middle layer in the same manner, and also reserve it for examination. The division of the inner layer from the endosperm is often only accomplished with difficulty ; in case they do not separate well, let the grain soak some time longer. Next proceed to examine these several coatings. Mount each on a slide in a drop of water (or preferably, when wished to examine the mount for some time, in a drop of glycerin), so that it is practically freed from bubbles, and lying flat and without creases. Put on a glass cover and press gently down. Examine with either a quarter or eighth-of-an-inch objective. Fig. 33. — Outer Layer of the Bran of Wheat, magnified 250 diameters. Observe in the outer layer that it consists of a series of cells, some four to six times long as broad, and arranged longitudinally in the direction of the length of the grain. A portion of the outer layer is shown in Fig. 33. Notice at the one end (of the actual section, not the figure) the beard of the grain, and note particularly the attachment of each hair to the skin (the root). Observe also the canal extending about half the length of the hair. Fig. 34 is a drawing of such hairs. Fig. 34. — Beard of Grain of Wheat. 260 THE TECHNOLOGY OF BREAD-MAKING. Next observe the appearance of the second layer of skin that has been detached ; this is shown in Fig. 35. Fig. 35. — Middle Layer of the Bran of Wheat, magnified 250 diameters. In this will be seen two layers of cells that are not both in focus^at the same time, the one layer being, in fact, underneath the other. There are in the first place a series of long cells arranged transversely to the longitudinal section of bran shown in Fig. 32, where they are marked c. Because Ahey are thus arranged around the grain of wheat they are frequently termed “ girdle '' cells. The great difference between looking at the same thing in one direction and then in another is strongly exemplified in this study of these particular cells in plan and in section. An instructive lesson may be gained by comparing the section illustrated in Fig. 32 with a similar section cut transversely instead of longitudinally. Such a section is given latter in the series. The colour-containing cells underlie those to which reference has just been made. In the next place examine the inner, or aleurone cell, layer of the bran. Fig. 3G.— Inner or Aleurone Layer of the Bran of Wheat, magnified 440 diameters. STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 261 The aleurone or cerealin cells of the bran are often referred to as being cubical ; that this, however, is not the fact is well shown in Fig. 36. They certainly have a square or rectangular outline when seen in section, whether longitudinal or transverse, but the skin, viewed on the flat surface, shows that the cells are irregular in outline, each accommodating its contour to that of those surrounding. There follows a sketch of the transverse section through the bran of wheat ; this should be carefully compared with the longitudinal section. Fig. 32. Fig. 37. — Transverse Section through Bran of Wheat, magnified 250 diameters. The actual section from which this drawing has been made is not so good a one as the longitudinal section, from which Fig. 32 was drawn. Viewed with a moderately high power it is difficult to get very much of the thickness of the section in focus at the same time ; still sufficient is noticed, on careful observation, to show the general structure of the bran. The outline of the aleurone cells is more irregular than was the case in the longitudinal section ; they are also noticed to be, in several instances, overlapping each other. Looking at the cells of the middle skin of the bran, they are seen to be of considerable length, justifying the remarks made about them when studying their appearance as seen on the flat. While, however, these middle cells are seen lengthwise, it follows of necessity that the ends of the cells of the outer skin must be presented to the eye. This sketch, taken with the others, gives a tolerably complete idea of the microscopical structure of a grain of wheat. A careful study of these sections of the wheat grain and of the various layers into which the bran can be divided should give the miller in particular a clearer and more real idea than he can otherwise have of the nature of these outer integuments of the wheat grain, which it should be his object to remove. The study should not merely be confined to the drawings given in this work, but should extend to the actual slides themselves under the microscope. 414. Bran Cellulose. — ^The bran of wheat consists largely, as is well- known, of cellulose or woody fibre, together with a considerable proportion of soluble albuminous matter. Cellulose may be obtained in a fairly pure state by alternate treatment with hot dilute solutions of acid and alkali. The actual structure of the cellulose of the different layers of the bran pos- sesses considerable interest, and may be studied in the following manner : Strip off the different layers of skin as before directed, put pieces of each in a separate test-tube, and first digest for an hour with dilute sulphuric acid ; pour ofl the acid, and digest with caustic soda solution for another hour. -Make up solutions of 1 part respectively of acid and£alkali, and 20 parts of 262 THE TECHNOLOGY OF BREAD-MAKING. water. Wash the resulting cellulose, and mount carefully on a glass slide ; examine under the microscope. Fig. 38. — Cellulose of Outer Skin of Bran, magnified 250 diameters. This is rendered almost transparent, and presents no striking differences in structure from the original skin. Fig. 39. — Cellulose of Middle Skin of Bran, magnified 250 diameters. In this again the resemblance to the skin before treatment is very notice- able. One special point of interest occurs in this drawing ; the two layers, of cells to which reference was made when previously speaking of the appear- ance of this layer have become separated. The upper cells extend over the whole field, wliile the lower or pigment layer is stripped from the one portion Tlie result is that the distinction between the two is seen very clearly. As tlie aleurone layer or inner skin of the bran contains so large a quan- titv of protein matter, it will readily be imagined that treatment with alkali will cause considerable difference in its appearance. STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 263 Fig. 40. — Cellulose of Aleueone Layer of Bean, with portion of protein] remaining, magnified 440 diameters. In Fig. 40 such a specimen is shown ; it will be noticed that a portion only of the protein remains, the greater part having been removed by the action of the caustic soda. Fig. 41. — Cellulose of Aleueone Layer of Bran, with only the slightest trace of protein still remaining in some of the cells, magnified 440 diameters. This figure shows in most striking fashion how small a proportion of the interior layer consists actually of cellulose. Reviewing the whole three layers, one finds that the outer one is largely composed of cellulose, and consequently is condemned as an article of human food. The middle layer contains less cellulose, but contains a higher proportion of colouring matter. The proportion of cellulose in the inner layer is still less, but the amount of protein is high. This protein body is injurious to the flour, inasmuch as it exerts considerable action on broken starch granules. There are therefore cogent reasons for the non-admission of any part of the bran into the flour. 415. Cellulose of Endosperm. — On taking a grain of wheat and carefully cutting off the bran so as bo have a piece of the endosperm only, and treating 264 THE TECHNOLOGY OF BREAD-MAKING. this interior portion of the grain with acid and alkali, a trace of cellulose is obtained which shows no distinctive organisation under the microscope. The student will do well to verify this fact for himself. Let him also treat small quantities of different varieties of flour in a similar fashion, and exam- ine the remaining cellulose. Such an inspection is calculated to teach much concerning the success of the operation of milling. He will be able to see whether or not the number of small particles of bran in the flour is large. He will also learn whether or not the bran itself is intact, or whether portions of one or other of the surfaces have been removed and ground up into the flour. Physiology of Grain Life. 416. Protoplasm. — In explaining the nature of yeast, Chapter IX., reference has already been made to the fact that the interior of the cells is filled with “ protoplasm,"' and that this material is the “ ultimate form of organic matter of which the cells of plants and animals are composed."’ Protoplasm has also been defined as the “ physical basis of life,"" and for that reason merits in this place some little examination. Yeast may be viewed as an unicellular plant, whereas wheat and the higher plants generally are multicellular in nature, so that yeast serves as an introduction to their study. From what has been already described of the life-history of yeast, the following conclusions as to the nature of its protoplasm may be drawn : First, that protoplasm is the seat of those chemical changes which are in- separable from the life of the organism. Such chemical changes, collectively, are termed the metabolism of the organism. Those processes which go to the building up of more complex chemical compounds are termed constructive metabolic processes, while those in which complex compounds are broken down into simpler compounds or elements are termed destructive metabolic processes In the most recent nomenclature, the term metabolism is sometimes re- stricted to the constructive processes, while the changes of destruction or degeneration are referred to as processes of katabolism. Vines classifies the fundamental properties of the protoplasm of the yeast plant as follows : — “I. It is absorptive, in that it is capable of taking up into itseK the substances which constitute its food. “2. It is metabolic, in that it is capable of building up from the relatively simple chemical molecules of its food the complex chemical mole- cules of the organic substances present in the cell ; and in that it is capable of decomposing the complex molecules of these substances into others of simpler composition. “3. It is excretory, in that it gives off certain of the products of its des- tructive metabolism. “4. It is reproductive, in that portions of it can become separate from the remainder, and lead an independent existence as distinct individuals."" The protoplasm of certain more highly organised unicellular plants have, in addition, other distinct properties, such as contractibility , irritability, etc. In the lower multicellular plants all the cells appear to be exactly alike, but in most the constituent cells vary and have special functions allotted to them : such groups or arrangements of cells constitute what is known as an organ. Thus, certain cells are absorptive in their nature, while others are excretory : others, again, are charged with the functions of reproduction, and these are known as the reproductory organs. The seed or grain of wheat is one of the most important among these latter, and it is only such other functions of the plant as are directly associated with seed life that can be touched on in this place. Like other parts of plants, the seed is built up of parenchymatous cells STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 265 containing modified protoplasm, wiiich consists of a series of meshes or network enclosing within them, in the ripe seed, grains of starch. The network portion is composed of proteins, and of these an exhaustive descrip- tion has already been given. The insoluble proteins constitute what Reinke named the plastin of the cell, while the more soluble portions are the globulins and peptones ; of which latter, seeds usually contain considerable quantities. The plastin is probably the organised protoplasm of the cell, while the globu- lins and peptones are unorganised or dead protoplasm. The higher plants, such as the cereals, contain in certain of their cells differentiated proto- plasmic bodies, which may contain colouring matter, in which case they are knovTi as chlorophyll- or etiolin-corpuscles ; or they may be colourless, in which case they are starch-forming corpuscles or amyloplasts. 417. Constructive Metabolism of Plants. — ^The roots serve as the absorb- ing medium through which the plant obtains water and substances which may be in solution in water. From the atmosphere plants absorb carbon dioxide. Much of the oxygen of this carbon dioxide is returned to the atmo- sphere in the free state, the carbon being used in the constructive metabolism of the plant. In addition to the carbon dioxide and water, the plant has at its disposal for metabolic purposes salts containing nitrogen and sulphur. A most important point in the study of metabolism is that the assimila- tion of carbon from carbon dioxide is eonfined to those portions of plants which contain green colouring matter (or closely allied matter to be subse- quently described). Further, the decomposition of carbon dioxide can only take place in the presence of light. On treating green leaves of plants with alcohol, the green colouring matter is dissolved out, and has received the name of chlorophyll. Within the leaves this ehlorophyll exists in cells or corpuscles known as chlorophyll-corpuscles, the chlorophyll itself having apparently a similar composition to other protoplasm. Etiolated plants — that is, plants grown in the absence of light — contain corpuscles in which the colouring matter is yellow, not green ; this matter has received the name of eiiolin, and is doubtless closely allied to chlorophyll in properties. On exposure to light, the etiolin corpuscles absorb carbon dioxide and exhale oxygen, the etiolin being converted into chlorophyll. Investigation of a most eareful and exhaustive nature demonstrates that the absorption of carbon dioxide aned exhalation of oxygen, with the formation de novo of organic matter in plants, is ssentially a function of chlorophyll (including etiolin), and cannot occur in its absence. But little can be stated positively as to the exact nature of the chemical changes induced by chlorophyll, but they may be summed up in the state- ment that it produces, by synthesis, protein matter. The first step is pro- bably the formation, from carbon, hydrogen, and oxygen, of comparatively simple substances, such, perhaps, as formic aldehyde, CH2O (the simplest possible carbohydrate), and its polymers. (Glucose and other of the higher carbohydrates may be viewed as polymers of formic aldehyde, thus 6CH2O =C6 Hi 206, glucose.) The next upward step might be the production of nitrogenous substances of the amide type (asparagin, etc.), and finally, by further synthesis, the still more complex protein. Differences of opinions exist as to the manner in which starch is formed by the plant — there is first the observed fact that the chlorophyll-corpuscles of a growing plant exposed to fight contain starch grains, and that these disappear during darkness. Vines is of opinion that “ the starch which makes its appearance in the chlorophyll-corpuscles, when constructive metabolism is in active operation, is not the first product of the synthetic processes, but only an indirect pro- duct : protoplasm is the substance which is formed in the chlorophyll- corpuscles, and it is only in consequence of the decomposition of the proto- 266 THE TECHNOLOGY OF BREAD-MAKING. plasm formed that starch is produced.” In a paper contributed to the Journal of the Chemical Society, in 1893, by Brown and Morris, these chemist advance the view that cane sugar is first formed as an up-grade product of constructive metabolism, and that the starch is formed within the chlorc- phyll-corpuscles from this compound. There is proof that protein matter is capable of being so decomposed as to result in the splitting off of a carbo- liydrate molecule from its substance, as in the production, for example, of the cellulose cell-wall of yeast from its protoplasm.^ On the other hand, Brown and Morris have shown that the chloroplasts of the leaf can form starch when fed directly with cane-sugar solution, and claim that “ both under the natural conditions of assimilation and the artificial conditions of nutrition with sugar solutions, the chloro-plasts form their included starch from antecedent sugar.” However, in whatever manner formed, chlorophyll causes, in the presence of light, the production both of proteins and carbo- liydrates, including starch, within the leaf. The final process of constructive metabolism is the conversion of dead protein matter into living organised protoplasm ; but our knowledge of the difference between these is very slight. Vines points out “ that the primordial utricle of dead cells readily allows of the passage into it and through it of substances which could not enter or pass through it in life. This is in accordance with the well-known fact that it is impossible to stain living protoplasm ; it is when protoplasm is dead that colouring matters can penetrate into it.” Having traced the synthesis of protoplasm and other organic matter in the leaf, the next problem is the mode of their translocation or transference to other parts of the plant. Brown and Morris have proved the existence in leaves of a diastase, which they term leaf diastase, or “ translocation diastase,” from its functions as an agent in the translocation of the chloro- phyll products. They show that by the agency of this diastase the starch (which during darkness disappears from the chlorophyll corpuscles of the leaves) is converted into maltose. They further are of opinion that the cane-sugar which the leaves may contain is converted into dextrose and Isevulose. Probably also the proteins are changed by analogous processes into peptones, and from these into amides, in which form the nitrogenous organic substances are most likely distributed through the plant. The diastase and proteolytic enzymes, then, pour into the various vessels of the plant a solution of maltose, dextrose, laevulose, and peptones and amides. These are carried to the new parts of plants for the purpose of forming buds, roots, etc., and to the seed portion, there to be stored u]d as provision for the young plant during its first stages of growth, and before able to obtain nutriment by the action of its own chlorophyll. The physical structure of the wheat seed or grain has been already de- scribed, the embryo of the plant being at the lower end, near where the seed is attached to the ear, and the upper portion being the endosperm, the whole })eing enclosed witliin the cuticle known as bran. Of the formation of the seed as the plant grows, we cannot here speak ; but assuming the seed to have formed its outer envelope, it before ripening is found, on examination, to be full of a milky looking fluid, which consists of the sap which is being supplied by the vessels of the plant. Within the seed a synthetical process proceeds, by which is caused the formation of protein matter from the sugar and amides supplied by the sap. From this is derived the starch of starchy seeds, while the residuum of the ])rotein forms what are known as aleurone-grains. Vines points out that comparatively little is known of the manner in which starch is formed in ^ Pavy, in some investigations of the chemical pathology of diabetes, shows that glucose may be formed from proteins during human digestion. STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 267 seeds, but it is assumed that it is produced in the same way as in other parts of the plant. Schimper has observed that in the parts of the plant not exposed to light, the formation of starch is effected by certain specialised portions of the protoplasm, which are termed starch- forming corpuscles or amyloplasts. These amyloplasts resemble in nature the chlorophyll cor- puscles or chloroplasts, and act by conversion of protoplasm, from which the starch-molecule is cleaved off by decom- position. They differ, in that amyloplasts act in the absence of light, and can only commence the production of starch from comparatively complex substances, whereas chlorophyll cor- puscles synthesise this body from simple inorganic compounds. The grains of starch as at first formed are very minute, but' grow by deposition of further starchy matter, such growth continuing either within the amyloplast, or frequently outside it, the latter being the case in the wheat grain. The mark on the starch corpuscle known as the hilum indicates the point of first growth in an externally formed starch grain, and is gradually separated from the amyloplast by the deposit of more starch in stratified layers, finally leaving the hilum at the far end of the longer axis of the ovoid starch corpuscle. After the separation of the starch, there remains behind in the seed a small proportion of sugar ; part of which consists of sucrose, and is probably an up-grade sugar, and the remainder of glucose or allied sugar produced by the subsequent degradation of the cane sugar. In some seeds the non- nitrogenous matter is stored up as oil instead of starch — comparatively little fatty matter is present, however, in wheat, except in the embryo itself. Fig. 42. — Group of Amylo- plasts. The residual matter of the protoplasm, after the separation of starch, is stored up in the form of small granules, known as aleurone-grains. These form the matrix in which the starch grains are imbedded, and constitute the protein matter of the endosperm. The series of cuboidal cells forming the interior layer of the bran are also filled with aleurone, and have the name aleurone-layer. During the growth of the seed from the milky stage before referred to, the sap continues to bring supplies of maltose and nitrogenous matters, which undergo the constructive metabolic process just described ; while under the influence of a ripening sun the water is evaporated. Gradually the contents of the seed acquire a firmer consistency, until at last the solid ripened grain of wheat is produced. In this condition the seed is in a resting stage, and may without injury be subjected to desiccation and extremes of temperature, which would be fatal were it in its active state. Under the influence of moisture and warmth, active changes are set up in the resting seed, and the development of the new plant commences. 418. Germination of Wheat and Barley. — In order to understand the phenomena of germination, reference should at this stage be made to the section of the wheat germ given in Plate VI. Although in the resting stage the wheat germ contains no starch, yet within twenty-four hours of the seed being kept in a moist state, starch is found in abundance within the germ, although no alteration has occurred in the endosperm, being doubtless produced by dissociation of the protoplasm of the embryo. This is followed by an elongation of the radicle, which at this stage contains starch, as do also the leaves of the plumule. The plumule, with its further growth, first bursts through the envelope, and finds itself in contact with the “ pericarp,’ 268 THE TECHNOLOGY OF BREAD-MAKING. or outer skin of the grain (enveloping the testa). The pericarp is next ruptured, and the growth of the plumule proceeds outside the grain. On looking at the figure of the germ (or, still better, an actual section under the microscope), there viU be noticed a series of elongated cells, constituting what is known as the scutellum : between this and the endosperm is a series of cells of another type, arranged with their longest diameters directed toward the endosperm ; these latter form what is called the absorptive and secretive epithelium. At the time when the radicle breaks through its sheath, the cells of the scutellum lying next the epithelium begin to show starch granules, which gradually pervade the tissue of the germ : these may be taken as the first indication of the passage of reserve material from the endosperm to the germ, while the epithelium is regarded as the absorptive contrivance by which the germ thus derives sustenance from the endosperm. The first visible effect on the endosperm is the breaking down of the paren- chymatous cell-walls, and following on this we have the starch corpuscles attacked. There are, in the first place, minute pittings on the surface of the grains of starch, which increase both in size and number until the whole granule is completely dissolved, with the formation of maltose. The disso- lution and assimilation of the starch of the endosperm proceeds gradually, the more remote parts being last to suffer attack. The protein matter of the endosperm is at the same time converted into peptone, and probably amides, by a proteolytic enzyme. By means of the epithelium, these are transferred to the growing plant. The aleurone cells of the bran show no signs of change until the reserve starch is nearly exhausted, when they begin to suffer attack, the cell-walls undergoing dissolution. Doubtless the function of the aleurone cells is to provide protein nutriment for the plant at a comparatively late stage of its growth, hence the highly resistant cell- walls. In their researches on the Germination of the Gramince, Brown and Morris demonstrate that the epithelium of the germ secretes diastase during germination, and this is the agent of transformation of the contents of the endosperm. They also, as has been previously mentioned, have shown that the diastase of germinating grain is cyto-hydrolytic (cellulose dissolving) as well as amylo-hydrolytic. They consider the former action to be due to a distinct and separate enzyme from diastase proper, and that it also is secreted by the epithelium. Two varieties of diastase have been described in the chapter on Enzymes, that from raw grain, and ordinary or malt diastase — the former is probably identical with the diastase of translocation, by which the starch of the chloroplasts is converted into sugar ; while the latter is essentially a diastase of germination, and is only secreted by the epithelium of the scutellum. Tlie power to liquefy starch-paste and to erode starch -granules always accompany each other, and, in fact, are never separable, being in each case functions of germination diastase, or diastase of secretion. Raw grain dias- tase is produced during the production of the embryo in the growing and unripe seed, and probably then acts as translocation diastase for the purpose of preparing nutritive matter for the developing embryo. The i3ortion of such diastase remaining unused in the ripe seed constitutes the diastase of raw or ungerminated grain. The changes just described are those which wheat undergoes during germination, and occur in an incipient form in sprouted or “ growy '' wheat, in wliich tlie diastase of secretion, together with cytase, will have more or less broken down the parenchymatous cell-walls, and also possibly have eroded some of the starch. A useful test for growy wheat is to examine tlie germ for starch ; if any such granules are found within a section when viewed under the microscope, it may safely be concluded that the wheat is unsound. The changes to which malt owes its properties are practically STRUCTURE AND PHYSIOLOGY OF THE WHEAT GRAIN. 269 the same ; when germination has proceeded sufficiently far, its further course is arrested in malting by kiln-drying the grain. Experimental Work. 419. The experimental work undertaken in connexion with the subject- matter of this chapter should consist in following its detailed directions for microscopic examination of wheat. CHAPTER XIV. CHEMICAL COMPOSITION OF WHEAT. 420. Principal Constituents of Cereals. — ^Proximate analysis of tne cereal grains shows that they contain as their principal constituents — fat, starch, cellulose, dextrin, sucrose, raffinose, and possibly other sugars ; soluble protein bodies, consisting of albumin, globulin, and proteose ; in- soluble protein bodies, consisting of glutenin and gliadin, which together constitute gluten ; mineral matters, consisting principally of potassium phosphate and water. The following, according to Bell, is the average composition of the differ- ent members of the cereal family : — • Wheat. Long- eared Carolina Constituents. English Maize. Eye. Eice Oats. without Winter. Spring. Barley. Husk. Fat 1-48 1*56 1*03 5*14 3*58 1*43 0*19 Starch 63*71 65*86 63*51 49*78 64*66 61*87 77*66 Cellulose 3*03 2*93 7*28 13*53 1*86 3*23 Traces Sugar (as Cane) 2*57 2*24 1*34 2*36 1*94 4*30 0*38 Albumin, etc., insolu- 1 ble in alcohol . . J Other nitrogenous 1 1 10*70 7*19 8*18 10*62 9*67 9*78 7*94 matter, soluble , in alcohol . . . . 1 4*83 4*40 3*28 4*05 4*60 5*09 1*40 Mineral matter 1*60 1*74 2*32 2*66 1*35 1*85 0*28 Moisture 12*08 14*08 13*06 11*86 12*34 12*45 12*15 Total 100*00 100-00 1 100*00 100*00 j 100*00 100*00 100*00 The following is a series of later analyses by Clifford Ricliardson of the various cereals. It will be noticed that the water runs very considerably lower than in Bell’s analyses, a result due probably to the greater dryness of the American climate. 270 CHEMICAL COMPOSITION OF WHEAT. Averages of Detailed Analyses of Cereals. 271 Wheat. ' Barley. i Oats. Maize. Eye. No. of Analyses—. 27 14 18 21 17 Fat 2-30 2-67 7-87 5-54 1-83 Starch . . 67-88 62-09 56-91 66-91 61-87 Cellulose. . 1-90 3-81 1-29 1-41 1-47 Sugar, etc. Dextrin and Soluble 3-50 7-02 6-07 2-18 7-57 Starch. . 1 Proteins insoluble in 80 ^ 230 7-45 3 55 7-86 3-47 13-43 2-18 i 4-96 4-75 9-07 per cent, alcohol . . j Proteins soluble in 80] per cent, alcohol . . j 3-58 3-66 1-82 5-84 1 2-53 Mineral matter . . 1-84 2-87 2-22 1-54 2-06 Moisture . . 9-25 6-47 6-92 9-34' ' 8-85 100-00 100-00 100-00 100-00 100-00 Ratio of Proteins to Car- bohydrates . . 6-9 6-5 4-8 7-6 6-5 In a later table compiled by Hutchison, the general composition of the cereals is given as follows : — Constituents. Wheat. Barley. Oats, Hulled. Maize. Eye. Bice, no Husk. Millet. Buck- wheat. Fat . . 1-7 1-9 8-1 5-4 2-3 2-0 3-9 2-2 Carbohydrates 71-2 69-5 68-6 68-9 72-3 76-8 68-3 61-3 Cellulose 2-2 3-8 1-3 2-0 2-1 1-0 2-9 IM Proteins 11-0 10-1 13-0 9-7 10-2 7-2 10-4 10-2 Mineral matter 1-9 2-4 2-1 1-5 2-1 1-0 2-2 2-2 Water 12-0 12-3 6-9 12-5 11-0 12-0 12-3 13-0 421. Banana and .Bread-fruit Flours. — Attempts have been made to introduce for bread-making purposes, flours prepared from the banana and bread-fruit. Ballard gives the following as their mode of preparation and composition : — Banana flour is prepared from the unripe fruit of Musa saj)ientium (banana), before any sugar has been formed therein. The peeled fruit is cut transversely in round slices, dried, powdered and sifted. It is much used in certain parts of the tropics in the form of porridge, damper, or cake. Bread-fruit flour is obtained from the dried unripe fruit of Artocarpus incisa, which on being powdered and sifted, yields an insipid non-saccharine substance used as food by the Tahitians. The whole fruit, while unripe, and still hard through its starch not having yet been converted into sugar, is also cooked and eaten as bread. 272 THE TECHNOLOGY OF BREAD-MAKING. Composition. Banana Flour. Cape Verde Bread-fruit Four. Tahiti Bread-fruit Flour. Water . . 1L90 13-80 14-30 Proteins 3-68 2-61 1-10 Fat 0-55 0-85 0-20 Starch . . 79-82 80-64 83-85 Cellulose 1-95 0-10 0-15 Ash 2-10 2-00 0-40 422. Analyses of English and Foreign Wheats. — ^The analyses embodied in the following tables are selected from those of a number of wheats analysed by one of the authors. Nos. 1-18 inclusive w^ere analysed in April, 1884 ; they are, except where otherwise mentioned, 1883 wheats. Nos. 19-27 inclusive were analysed in September, 1884, and are all 1883^ wheats. Nos. 28-38 inclusive were analysed in November, 1884, and are all 1884 wheats. Reviewing Nos. 1-18 as a whole it may be remarked that the moisture- is high ; as might be expected No. 18 heads the list. The soluble extracts and proteins average a somewhat high figure. Taking the glutens through- out these are lower than in foreign wdieats, the highest figure being only 8*21. As might be expected the Revitts are exceedingly low ; the trace of gluten was so small that it was practically impossible to recover it from the bran. Of the other wheats. Nos. 6 and 18 contain the lowest quantities of gluten. Samples Nos. 19-27 call for no special remark, representing as they do the class of wdieats largely used, particularly in the south of England, in the manufacture of flour. It is interesting to note the variations in the charac- ter of the same variety of wheat when grown in different localities, and under different conditions. Nos. 19 and 20 were considered by sender, a miller whose flours are familiar in the London market, to be exceptionally fine samples of their kind. No. 21 is of interest as showing the composition of a wlieat damaged during growdh. The English wheats of the harvest of 1884 were of exceptionally fine quality. The samples given were selected from the South and Western Counties. Compared with the series of English and Scotch wdieats of 1883 liar vest the moistures run much lower, the average being 13*55 against 14*82 in the 1883 wheats. The same remark applies to the soluble extract and soluble proteins. The average of the glutens is also somewhat lower, being 6*40 against 6*87. The lowest gluten of the 1883 series was 5*00 in a Scotch West Country wheat ; this had also the highest moisture ; like the Scotch sample. No. 38 in the new series is grown in a damp climate, S. Devon, and yields the same percentage of gluten. The highest gluten, 8*61, is yielded by a sample of white wheat, the highest of the 1883 wheat being a saipple of rough chaff grown at Didcot, and containing 8*21 of gluten. Although made some time ago, the foregoing analyses are still fairly representative of tlie general composition and character of English wheats. Many new varieties of wheat have now been introduced and have dis- placed older kinds to a very great extent. “ Tiverson’s ” and “ Webb’s Stand-up ” are two kinds largely grown in England at present. English and Scotch Wheats. CHEMICAL COMPOSITION OF WHEAT, 273 oS .22 o ^-1 22 .jo ^ ® ce ^ w -5 g g &c® +3 ^ c*^ t- .2 k O ..:S O ^ a. bC fl|=b ^ pC 0 © O ^ C =3 S III 15 O Ph bD . fl ■S g.22 ® 2^ 3 © S bc 5^ ' S wh 33 >■ § s “ -g 3 ^ 43 o 3 n; ^ 3 ^ “ 3 - 3 V 43 bc ® ^-3 o3 bC tH _ ® ® 3 ^ T3 •'■' 3 §33 S.^O Mg O ^ 43 B 6 oM 3 r-i 43 S O O 3 a g § o %t ^.3 o SI'S I g g ® ® o ® S ^ M o ^ ^ a bio ® 3 T3 .s ^ ® g ;a 3 s 'S .rt ,3 © P^3 bC P S 3 'n .B o3 o ^ tc ^"30 I a o ^ 3 © ® 3 33 § ^ )8 ® © cc s.s cS 03 CC 43 02 ® ’^2 T3 © 3 “ § 3 2 © .3 43 bC fB IB bC 43 CC 3 3 ; oc .^Po Mg lyT ^ 33 33 O SC 3 £ 02 > .3 33 ® © _c 3 3 o3 ...33 O - 3.:: 3 3 . 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CHEMICAL COMPOSITION OF WHEAT. 27 ’ » o o3 O « CO © ^ O tH cc c 5 .2 r< O tio © cS G c 3 S G So © .. g ©mm ^.S © Gh c 3 •_S rG ^ k r& 1^0 «4— I ^ 5 o o pc -p ^ 0 cS M p s £“5 0 ® G 3 -G .§ II b g: M 9 ^ © tiC-G > -p G P © S .G $ © p -p ^ G _M bO '0 G 2 .9 .2 ■GJ ^ ^ -2 - 2 cs o MS M ^'rG ^ §-2 to oS Ph ’o s © © bD TJ .2 G § ^ G -§ ^ ^ ' bCt 3 3 3 i I I I I I I PP .G m G ' p -P - 2.5 S •G > t: t: ^ © 2 -§2^8 » I s J © "" 9 g3 ^ M '::^ bo P ^ bc O G G g3 ^ g-g G > ^ 9 'bb^ ‘ o • M P P ® G G P G p .2 O 'G 9 © -P TO rP G-I G ^ ri 2 ^2.2 ^ § ■p 2 ^ p 2 © -5 .9 c2 H •ja^jauiojTi8jy r JO jTjSpH I I I I I I I I I I I I I I I I I I I I I l-^Jd OJ I ^ laAV JO ^ • I on-en I ^ 1:0 l>- ^ G 1 t^O 00 »OQ 0 00 t;*C 5 ':^t^ 00 Q 01 > 0100 i 0 t^C 5 G^COCqC^CNC^G^G^G^C^G^GqOJGqC^G^CNC^ ••^jcr CD 10 O l-H lO t- tP CD 00 OOO'— iCCi— I»0(M-^000>OOIOOCD(NO CD'^OcpcOOOCD-^CqcOCJCOOJi— i-^oOCMO C 5 d 50 cbcil:^ClOCDobiOlP« 01 >i-PC 5 C>d 5 0 1 •JOAV 21-5 14-7 190 18-0 22-5 26 0 300 OOOOOOOOOOOOOJ© »DOt;*t;'P10pDJD50l>-QOoOCOCqOOpO 666r-it^666666rp6>-H69i66 G— iDqrHD1r-iG (M 0 CO (M Dq CO ^ CD CD CD 0 CO >— • 05 (M p p p p p 9 cq ^ l-H p P 0JTl^STOJ\[ 0 05 6 6 6 6 6 6 6 6 rH pP 6 6 l-H l-H l-H rH rP I-H i-H I-H I-H I-H I-H l-H l-H ^ Ip P 0 00 TtH CO j— 1 0 0 CD 0 0 qaqsng; jod 10 i-H 0 pi CD 1 1 1 »D 1 pj 1 1 p 9 1 3 00 6 t+h 6 G-i 6 1 1 1 6 6 1 0 1 1 6 ID 1 CD 10 CD CD ID CD CO CO CO CD CD CD CD c3 P ^ G 2 W w .-t^ G 5 3 o 5 CB M • p • ® I 33 p G n 2 ©f^ "G 'G ^ ©35 pH^h^ G 2 . ^ 2 : cs G G 2 ^ G rG 'G! 2 g © .2 ’p M © bO G 1 ^ M bD ^ G ©'§, o S Ph Average Composition of American Wheats, 278 THE TECHNOLOGY OF BREAD-MAKING. •gio lO lo lO lO lO lO o lO >0 CO o C000100100Q00510 •SUp^OJJ §9 ^ i-H 1— 1 O hJH 00 rH tJH o: OO rH1005rHl000l0CDrHO Ci o O 00 05 05 05 o 05 GO 05 C5OrHOOOcbOrHG0 p-i rH 1 — 1 rH pHrHrHrHrHrHrHrH •^lO 00 (TO lO ir^ o 00 CO o O CO lO G0C0C0C0O1010C0t* Oi a tr^ CD CD o d CD CD CD Ippppp-^ppp ^ib lb lo ^ CO ^ lb --4 •4^ ^ H^cocococococoibib | "S rH rH 1:- H^H d CD lO 05 05 (' dt^OOCDCOQOOCOt^ •U9§0J';TJ^ SOi 00 05 O CO ir- p p p p p r- O500i-H0000t>’'— IrHCO 0) 1^ Ph rH rH Cl rH rH rH i-HrHddrHdrHddrH •gio CO lO CD o GO lO rH GO CO CD dt-10rH^DCD10'4^rHO OCDrHlOlOCDrHrHCOCD •SUP^OJJ CO rH CD GO CO CD t-- I-- CO 5r! rH (N GO O d rH rH drHcbdrHdrHCOCOGO p^-— 1 rH nH rH ! r-H r-H ^H ^H rH rH rH rH rH rH r-H rH rH rH 550 - 1— tr t-. fl CO t- rH Cl 00 05 lO 05 rH O lO --H ,CDl:-O05C0G0rHG0G0 •no O r— 1 rH p d p d p o d p d d ppppppppp febq Ph Cl d d d d d d Cl Cl Cl Cl drHdCldrHdCld I lo CD 05 CD lO o CD 05 CO C0'4^1OO5drH'4^rHrHTt^ •qsv S 00 1>- p p IQ P p P P pppppt^ooodoo P^ rH rH rH r-H rH rH r-H rH r-H r-H d rHrHrHr-HrHrHrHi— Idr-H : -(i r— d l-H d d t*h o CO ■4^ Q0rHC005OOOC0I>*-4l ! dl>*00rH00CDQ0OlOI>* ! lO o p p p p p p 1 "o 6 6 6 05 05 6 6 6 6 6 6 1— ioood50'-Hob5bi ’ p^^ rH r-H rH rH rH i—H rH rH rH rH r-H rH rH r-H •suiBaS 001 mOO CD TtH lO CO CO CD tH 05•4^0dT^l'4^^-d'4l S^ CD o O ^ d 05 4H 05 I-' rH |CDlOlCOlOOT^^GOT^^ JO jil8i9AV 2 p P P CO CO lO CO lO p CO 1 p^rnppdGOCDO oco CO CO CO lb CO CO CO CO CO CO CO cococbcococod'T^ib cS ce m O • ..H • a sf o i 3 O • pH • -S Ph CO c» o t/3 5 S t ^ c3 ( ' t; 1 ^ 1 1 i-* Atlantic and Gull The Middle West West of the Missi The Pacific Coast Canada . . Pennsylvania . . Maryland Virginia. . Georgia . . North Carolina Alabama Michigan (Kedzie Michigan Kentucky Tennessee Missouri Minnesota Kansas Texas . . Colorado Oregon . . •S98X1BUV R iHcb ^ 1— IpHi— li-Hi-Hi-Hi-Hi-Hi-Hi-H pH i-Hi— (pHi-HCl>'ppp-^p fc.GbobdsCOO'^COcbd5C^l>d5GO?005'X>I:^i-Ht>OrHrH(NC^rHGbi— lO ^ ^ ^ ^ i-H i-H pH nH ^ rH p-i erHGbot^O'^OOOC^i-HC^'— i6:i-HOOI> ^ 1 — I I— li— I Ii— Ir-Hi — 1 I-H p 2 l C CO O O (M 00 g^p^'^p01pC^C^p-prHi-Hi-HrHi-Hpp»t^l>-coi>-t^t^t^l>»i>»t^t'»lr^t^cot^t^t'*t^t^l7-coco ®1> pppooooooooo 0 0 fi ^ C>.‘^(M(MeOCOC ■Sim -t^C0C0 f S 1 '1 1 ' ' ' ' ' ' ' ' 4 ii » -i f I -9 '3 § -r! ’-I IS ' — ' — — ' — 'r^;O0f3?c5?f3c3c6^ . C C . C . ^ ^ . .Sh . g .03 .43 . *42 . c 3 O 03 o^OgO pJ O PhO AO ^Q^Q^Q--3P §>0 §Q |P^Q §P gP SP gP gP gP 280 THE TECHNOLOGY OF BREAD-MAKING. 425. Composition of Wheats, Fleurent.— Fleurent gives the following as the composition of certain hard wheats examined by him, viz., Russian, Algerian, and Canadian wheat. (The last, however, contained from 25 to 30 per cent, of soft wheat.) The relative weight of endosperm, embryo, and husk, is of interest : — Russian Algerian Wheat. Wheat. Average weight of a grain in grams 0*030 .. 0*048 Constitution, per cent. : — Endosperm . . . . . . 84*95 . . 84*99 Embryo 2*00 . . 1*50 Husk 13*05 . . 13*51 Composition of the Entire Wheat. Water Nitrogenous matters : — Gluten Soluble (Diastases, etc.) Ligneous, of husk Starch Fatty Matters Soluble Carbohydrates .* — Sugars Galactose . . Of husk . . Cellulose Mineral Matters Undetermined and loss . . 11*42 . . 11*34 . . 14*76 . . 11*00 . . 2*25 1*82 . . 1*92 1*90 . . 50*15 . . 55*05 . . 1*18 1*93 . . 2*14 2*68 . . 0*65 . . 0*46 1*76 2*19 . . 9*73 . . 9*40 1*56 1*42 . . 2*48 . . 0*81 Canadian Goose Wheat. . 0*037 . 84*94 2*05 . 13*01 11*36 10*88 1*67 1*91 54*55 2*70 2*18 0*75 1*90 9*21 1*35 1*54 100*00 . . 100*00 100*00 The gluten of the Russian wheat was found to contain : gliadin, 46*45 ; glutenin, 37*89 ; congluten, 15*66 per cent. To the congluten, Fleurent ascribes the tenacity and want of elasticity of the flour of these hard wheats, w^hich make inferior bread (Com'ptes Rend. 133, 944). 426. Durum Wheat, Norton. — ^This variety of wheat, Triticum durum, is largely grown near the Mediterranean, and in Southern Russia, for the manufacture of macaroni. Of recent years it has been somewhat exten- sively grown in America, and used in the manufacture of bread flours. In consequence, durum wheat has attracted considerable attention, not only in America, but also from European importers of American flours. An extensive investigation of its properties was carried out at the South Dakota Agricultural Experiment Station, U.S.A., by Norton, with the following results. Samples of the wheat were grown at the station and compared with European durum wheat, and also other American varieties of wheat. The Grain. The durum wheats have a very large kernel, being nearly twice as large as that of ordinary bread wheats. The grains are hard, of an amber colour, and appear almost translucent. Composition of the Wheat. In order to compare the general composition of durum Avheats with the bread wheats, a proximate analysis of Kubanka, one of the best Russian durum wheats, and one of the best American bread w'heats (Blue Stem, Minnesota), was made. The results of these analyses, together with the mean of American wheats as published by the Bureau of Chemistry of the Department of Agriculture, U.S.A., are given in the follow- ing table. CHEMICAL COMPOSITION OF WHEAT. 281 1 Constituents, Kubanka Durum Wheat. Minnesota Bread Wheat. Mean of American Wheats, ; Water . . . . . . . . . . i 9-32 6-00 10-62 f 1 Mineral Matter 1-71 2-46 1-82 1 Fat 2-34 2-49 1-77 Crude Fibre . . 2-52 3-35 2-36 Crude Protein, N x 5-7 14-46 13-21 12-23 Carbohydrates other than Crude Fibre 69-65 72-49 71-18 Sugar . . I 3-26 1-42 — Dextrin j 1-25 — — Invert Sugar, Soluble Starch Nil Nil This wheat was found to be remarkably sweet, and hence the sugar was determined with as shown, a very high percentage. The dextrin is also extremely high as compared with quoted analyses by Stone, in which 0*27 and 0*41 per cent, respectively of dextrin were found in whole wheats. In the case of the flours, as a result of indirect indications, macaroni or durum flours are estimated to contain from 1 to 2 per cent, of sucrose as against 0*18 and 0*20 per cent, in two samples analysed by Stone. Protein Content of American Crops. In American durum wheat crops, there is an increase in protein matter as against original imported seed. The following are some results calculated to the water-free basis : — Number of Analyses. Protein, N x 5-7 per cent. Imported seed .. 7 15-73 Crop of 1901 . . 31 18-13 „ 1902 . . 32 14-57 „ 1903 . . 45 17-34 The year 1902 was a very unfavourable one for durum wheat. Durum Flour. A straight flour was prepared from durum wheats, apparently of the 1903 crop, and various determinations made thereon. Colour. The durum wheats possess a yeUow colouring principle which is also found in the flour, which is in consequence of a deep yellow tint expressed on the Lovibond tintometer scale by 0*25 yellow + 0*17 orange. This colouring matter is soluble in alcohol and ether, but is insoluble in distilled water. It is somewhat readily soluble in dilute alkalies, and is 'discharged from solution by acids. (It is probably as a result of a similar reaction that flour is stained yellow by the addition of sodium carbonate.) Protein . — The following are the means of a number of determinations made on durum flours : — Crude Protein . . Wet Gluten Dry Gliadin . . „ of total Protein 15-00 per cent. 53-77 17-68 7-87 47-17 The gliadin determinations are calculated on a water-free basis. The durum flours have a large gluten content, but the quality is not good, usually showing very poor adhesive qualities, and but little elasticity. These are properties commonly ascribed to lack of ghadin. Though all the durum flours have high glutens and sugar contents, yet the bread from many of the poorer durum wheat flours neither rises during the fermentation nor in the oven. 282 THE TECHNOLOGY OF BREAD-MAKING. Bakers' Tests. On being subjected to a baker’s sponging test in which the flour is made into a sponge, allowed to ferment, and the volume read off, the volume of the best durum flours was as high as that of the bread wheat flours. In baking tests, durum flour becomes more sticky than bread wheat flours ; also if the doughs are a little too stiff they do not rise properly, and the bread is heavy and of poor texture. With a sufficiency of water, the volume, weight, and texture of the best durum wheat breads compare favourably with those from the best bread wheats, and the flavour is decidedly pleasing {Jour. Amer. Chem. Soc., 1905, 922). 427. Voller on Wheats. — The tables on pages 234-9, headed “Dictionary of Wheat,” are taken from Voller ’s excellent work on “ Modern Flour Mil- ling.” They are particularly valuable as a succinct record of the milling and baking characteristics of the most important wheats and their flours to be found on the British market. Mr. Voller has very kindly made specially for this work a number of corrections and additions to these tables, thus bringing them down to actual date. Voller also gives some useful rules as to selection of wheats for different characters, and also a table of mixtures equivalent to certain single wheats, which may be used to replace the latter on their becoming exhausted. Thus — For largest loaf, use good Minnesota or Manitoba, run very close by fine Saxonska, Azima or Ghirka. For whitest flour, use good White English, Oregon, Australian, or Ros Fe Plate, with choice for the latter. For sweetest bread, use good English and Manitoban in about equal parts. The following are examples of replacing mixtures, but are not intended as exact equivalents in any sense : — * Single VV’^heats. 2 American Spring | 2 Red Winter American . . . | 3 Manitoban | 1 Manitoban 2 Australian | 2 California (or Walla) . . . . | 2 Red Winter American . . . | 2 Californian or Australian | 2 Mixed Indian | 2 Bar-Russo Plate | May be replaced by 1 Manitoban. 1 Red Winter Kansas. 1 Bahia Plate. 1 Ros Fe Plate. 2 Saxonska. 1 Ghirka. 1 Ghirka, Azima, or Ulka. 1 Californian or Walla. 1 C.W. Kurrachee 1 Australian. 1 Chilian. 1 Plate. 1 Canadian (Soft). 1 White Bombay. 1 Walla. 1 Australian. 1 Bahia. 1 Manitoban 1 Calcutta,No. 2,or Red Kurrachee. 428. Chemical Changes during the Formation and Ripening of the Wheat Grain, Teller. — ^The following experiments were made in Arkansas, U.S.A., 1897. Half an acre of growing grain was purchased early in May, and on the 22nd instant, when the wheat was past blossoming, and the grain was set, a portion was cut. A further portion was cut on each successive day, * The best substitutes for English sorts are the following : — Soft Canadians, and Winter Americans, Dantzic, German, French and Mild Plates. CHEMICAL COMPOSITION OF WHEAT. 283 till forty-two portions in all were obtained. The portions ranged in weight from 80-90 pounds at the commencement to about 50 pounds at the close of the series. Immediately on cutting they were carefully air-dried, and then stored in bundles till threshing time. The summer was unusually dry. The wheat was threshed and cleaned at the end of September. Analyses were then made on samples which were hand-picked to free them from all foreign matter. For various reasons the forty-two samples were arranged in fourteen groups of three each. The following table shows the — Stage of Development of Wheat when Cut. Koman numerals indicate number of the group of three cuttings each. Figures in parenthesis indicate numbers of the cuttings. I. (1, 2, 3) A little past blossom. Grain set. II. (4, 5 , 6) Berries one-half to full length of ripe grain. III. (7, 8, 9) Crushed berries exude a thin milky liquid. Lower leaves beginning to die. IV. (10, 11, 12) Grain well in milk. V. (13, 14, 15) Heads and kernels well developed. Interior of the grain a thin dough. VI. (16, 17, 18) Grain in dough. VII. (19, 20, 21) Grain in stiff dough. Straw becoming yellow at butt. Grain shells a little with rough handling. VIII. (22, 23, 24) Straw in field much yellowed but still decidedly green. IX. (25, 26, 27) Grain oozes a thin liquid when crushed betAveen the thumb nails. Contents still slightly viscid. .StraAv still a little green. X. (28, 29, 30) Wheat fit to cut at beginning of this period. Straw has lost all its green colour and is dark purple immediately below the heads. Berry nearly dry. May be crushed between the thumb nails but without contents adhering to them. XI. (31, 32, 33) More than ripe. Straw bright and stands up well. XII. (34,35,36) XIII. (37,38,39) XIV. (40,41,42) The wheat was of the variety known as the Fulcaster. It is a red, bearded, wheat which is extensively grown in Arkansas. 284 THE TECHNOLOGY OF BREAD-MAKING. DICTIONARY OF WHEAT (FOREIGN Wheat. Quality of Bread. Yield ! Weight of Sort. 1 i Colour. Structure. Taste. Strength. Colour. of i Flour. Wheat per Bushel. AMERICA (UNITED STATES). i Michgan . . White Soft or mild Sweet Moderate Good 68-72 60-63 Oregon White Mild Dry insipid Low Fine 70-74 ' 1 61-63 Blue Stem . . White Mild, dry 70-74 61-63 Walla Walla White Dry to brittle Poor, insipid Fair to good 68-71 60-62 Californian . . White >> 99 Good to fine 68-72 60-63 Goose or Durum Yellow Very hard Dry, coarse Low to fair 62-66 60-62 Wheat CANADIAN (Soft) White Mild, soft Sweet Fair Good to fine 68-72 60-63 CHILIAN . . . . W or M Dry to hard Insipid Low 68-73 60-64 ARGENTINE. Plate — Candeal . . Yellow Hard, flinty Coarse Fair to good Poor to fair 62-66 60-64 „ Saldome . . Yellow „ 62-66 60-64 OCEANIA. Australian — V ict or - White Soft to dry Sweet Fair Good to flne 70-74 61-64 ian & New S. Wales South and West White ,, ,, 99 70-74 61-64 Australian New Zealand White Soft, mild 99 Low to fair Fine 70-73 61-64 INDIA. Bombay (Soft) White Mild, dry, or brittle Strong Fair to good Good to flne 70-73 62-64 Delhi White „ „ 70-73 62-64 Kurrachee . . W or M 1 Fair to good 66-70 60-64 Calcutta W or M 66-70 60-64 GERMANY. Dantzic White Soft, mild Sweet Fair Good to flne , 68-71 60-63 Konigsberg . . White 68-71 60-63 Rostock White 68-71 60-63 RUSSIA. Taganrog Cones . . Yellow Hard, flinty Dry, coarse Low Low to fair 62-66 60-63 Kubanka Cones . . Yellow Good or sweet Good Fair to good 64-70 60-63 EGYPTIAN . . . . White or mixed Mild to hard Dry, coarse Low Low to fair 64-72 68-62 ENGLAND. Talavera White Mild, soft Sweet Low to fair Good to flne 68-72 60-64 Chidham White ■ 99 68-72 60-64 Rough Chaff.. White 99 99 „ 68-71 i 60-64 Webb’s Challenge W’hite 99 68-71 60-64 Hallett’s Victoria White „ 68-71 I 60-64 Salvator White ,, 67-70 , 60-63 Essex WTiite . . WTiite 1 ” 68-71 1 1 60-64 CHEMICAL COMPOSITION OF WHEAT. 285 raiTES AND ENGLISH). Impurities Present. 1 Regular. Occasional. Pro- bable 0 /o General Remarks. Chaff, screening, Dirt, oats, barley 1-3 Clean, good wheat. Satisfactory substitute for seeds, maize English. Chaff, oats, barley. Smut, stone 1-3 Fine handsome grain. Low cleaning loss. High seeds flour yield. „ „ „ Smut, dirt, stone 1-3 ,, ,, ,, ,, ,, Chaff, smut, oats, j Dirt, stone 1-4 Yellow tint to flour. Fair quality as 2nd class barley, seeds white wheat. Short straws, smut. Oats, barley, stone. 1-5 Invaluable mixing sort. Useful all-round white. seeds, screenings scented seeds Maize, chaff, screen- Peas, oats, barley. 1-4 Low flour yield. Washing alone can tone its ings dirt hardness. Difficult to flnish. 1-5 A good coloury wheat of mild character . Stone, dirt, seeds. Oats and barley 2-6 Variable quality. Well worked mills a dead white chaff flour. Very fine in grain. Oats, barley, seeds Dirt, smut 2-6 Needs careful washing and milling. Not good flouring wheat. 2-6 i » 1 Chaff, screenings Oats, barley, seeds 1-3 Choice colour wheat. Valuable with reds as mixing. 99 99 1-3 1 „ „ „ 1-3 : Stones, dirt, gram. Oats, barley 3-6 Variable. Often fine quality, but purchases need seeds close watching. Indians all need washing. 99 99 99 ,, ,, 3-6 99 99 99 99 99 99 99 99 ,, ,, 3-6 Useful blending sorts. Absorb water freely. Fair colour. „ ! 3-6 Chaff, screenings. i Oats, barley, smut 2-5 Excellent mild w’orking colour wheat. dirt 99 99 99 ,, ,, ,, 2-5 ,. .. ,, ! » - „ 2-5 Oats, barley, seeds. 1 Smut, dirt, stone 2-6 Very hard to mill. ' Low in flour yield. rye : „ 1-5 Strong hard grain. Washes to advantage. Dirt, stone, seeds. 1 Peas, beans 3-8 Washing absolutely needed. Colour of flour dead barley white. Chaff, screenings Seeds, garlic, smut. 1-2 Large good wheat of top quality. dirt, vetches ,, ,, 1 ,, ,, 1-2 Brilliant handsome quality. Highest colour form. 1-2 1 9 Very reliable and a general favourite. 1-2 Unexcelled for colour when well grown. ,, ,, ,, 1-2 Large, but hardly fine quality. Too coarse. ” ” 1 » , 1-2 i Fine medium grain, clear skinned and white. 286 THE TECHNOLOGY OF BREAD-MAKING. DICTIONARY OF WHEAT (FOREIGN) Wheat. Quality of Bread. Yield of Flour. Weight : of Wheat per Bushel. 1 Sort. Colour. Structure. Taste. Strength. Colour. ENGLAND — contd. Red Lammas Red Mild, soft Sweet • Low to fair Good to fine 67-70 60-64 Nursery Red 67-70 1 60-64 Riddle’s Imperial . . Red - ! 67-70 1 60-64 Browick Red Good 67-70 60-63 Square Head Red ,, 5 , 67-70 60-63 Square Head’s Mas- Red ,, 5 , 67-70 60-63 ter April Red ,, 5 , Fair to good 65-68 60-62 Blue Cones . . Red Dry to hard 5 , 66-69 60-63 Rivetts Cones Red ” 66-70 60-63 Golden Drop Red Mild, soft 66-68 60-63 Prolific Red Good 67-70 60-64 Windsor Forest . . Red - 67-70 60-64 FIFE (new type). Red Firm to Hard Good „ 68-72 1 60-66 SCOTCH . . . . R or W ” i „ 67-70 1 60-63 IRISH .. R or W 1 ” 67-70 60-63 DICTIONARY OF WHEAT Wheat. Quality of Bread. Yield of Flour. Weight! of 1 Sort. Colour. Structure. Taste. Strength. Colour. Wheat per Bushel ! AMERICA (UNITED STATES). No. 1 Hard Spring Red Hard Sweet Full Good 70-72 60-65 No. 1 Northern ,, Red ,, ,, „ ,, 68-71 58-64 j 2 Red Good to full 67-70 57-63 No. 2 Chicago ,, Red Good 67-70 57-62 No. 3 Spring ,, Red Fair to good Fair 62-66 56-60 No. 1 Red Winter Red Mild, dry Fair Good to 70-73 60-64 (Choice) choice No. 2 Red Winter Red Good 68-72 58-62 Kansas Winter Red Hard Fair to good 67-71 58-62 (Hard) Western Winter . . Red Mild or hard 66-70 57-61 1 , ! 1 ' CANADIAN. No. 1 MANITOBAN Red Hard Good to full Good 70-73 60-65 No. 2 Red Good >> 68-71 58-64 No. 3 1 >> 68-70 58-62 CHEMICAL COMPOSITION OF WHEAT. 287 WHITES AND ENGLISH)— Impupjties Present. General Remarks. Pegular. Occasional. Pro- bable o/ /O Chaff, screenings. Smut, garlic, seeds. 1-3 Safe old-fashioned sort. Works very white. i vetches dirt 1-3 Small regular grain. Excellent quality. 1-3 „ ■ „ 1-3 Large bright red wheat. Average working sort. ,, ,, j ” 1-3 „ ,, ,, „ „ 1-3 1-3 Thin grain. Not of highest milling quality. » >» ^ ,, ,, ,, 1-3 In good repute for fine taste and colour. ,, ;> t 5» J> 1-3 Makes weak, coarse grained flour of dead white ’’ ” ” 1-3 colour. Rather a low class among the native reds. f 9 9 9 9 9 1-3 Good standard quality. Liked by millers. „ 1-3 » \ 1 ! „ „ „ i Seeds and dirt 1-2 Valuable type grown from Manitoban seed. 1-3 Like much of the English, rather too soft and weak. ” ” ” t 1-3 (FOREIGN REDS). Impurities Present. General Remarks, Regular. Occasional. Pro- bable % Cockle, seeds, spelt. Peas, barley smut. 1-3 The premier strong wheat. Reliable for grade and white oats, chaff. stone working quality. maize 1-3 Nearly equal to No. I. Hard for strength. In good 2-5 repute amongst millers. Less reliable than No. 1 of same class. Thinner, 2-5 with more waste. A safe grade of moderate strength. Small bright 3-8 wheat. Must be handled with caution as being distinctly Cockle, grass seeds, Peas, seeds, garlic. 1-3 a risky grade Should be long berried of brilliant quality. Works oats, maize stone, barley mild and white. „ „ „ Stone, garlic, peas. 2-4 A safe and favourite grade. Dry and mild, with- barley Stone, peas, barley 2-4 out great strength. Usually clean and regular. Of hard ricey struc- i „ Smut, peas, barley 2-5 ture. Moderate strength. | An off grade — not invariably regular in quality, j Cockle & seeds,spelt. Peas, dirt, stone. 1-3 Fine handsome as grain. Larger, but hardly as white oats, maize barley strong as Duluth I. » 2-4 Good as a substitute for I. Northern Spring, though 2-4 a trifle weaker. Useful as a cheaper substitute for No. 2 grade. 288 THE TECHNOLOGY OF BREAD-MAKING. DICTIONARY OF WHEAT Wheat. Quality of Bread. i ■ Yield of i Weight of Wheat per Bushel. Sort. 1 Colour. Structure. Taste. Strength. 1 Colour. Flour. P CANADIAN.— co»f(Z. 1 ! No. 4 MANITOBAN Red Hard Variable Low to fair Fair 62-65 ! 56-60 (SometimesFrosted) Canadian (Soft) . . Red Soft or mild,dry Sweet Fair Good 70-72 : 60-62 RUSSIAN. 1 Choice Azima Red Hard or med. hard Dry, strong Good to full Good 68-72 i 60-65 ,, Ghirka Red 99 ^9 Good ,, 68-72 ^ 60-65 Azima, 2nd quality Red „ Fair to good Fair to good 64-68 ; 58-62 Ghirka ,, „ Red 64-68 ; 58-62 Azima or Ghirka, third quality Red Soft or med. hard Fair Low, uncer- tain 60-65 1 1 55-60 Saxonska Red Dry, hard Good Good to full Good 68-72 60-66 Norfh Russian Red 68-72 1 60-66 Polish Red Med., hard, or mild Sweet Fair to good 66-71 i i 60-62 Siberian Red Medium Dry, strong ,, „ Fair 65-70 56-60 Ulka TURKEY. Red Mild to Hard Good Good Good 66-72 1 60-64 Danubian, first quality Red Hard or flinty Dry Low, fair to good Fair to good 68-72 60-64 Danubian, second quality Red Med. hard to flinty Low to fair 66-70 59-63 Salonica Red Dry to hard 1 Fair to good 66-70 60-63 Dede Agatch Red » 1 ” 66-70 60-63 HUNGARIAN (Hard) Red 1 Dry hard to flinty 1 Dry, sweet ! Good to full Good 68-72 60-64 ARGENTINE. Choice Plate, No. 1 j Red Mild to dry hard Sweet Fair to good Choice 67-70 62-64 Barletta (Ros Fe) 59-63 F.A.Q. Plate, No. 2 Barletta i Red Mild to med. hard : Good to choice 65-68 Bar-Russu (Barisco) Red Hard Sweet Fair to good Bright 66-72 60-65 Bahia 1 Red Mild to dry hard Sweet Fair to good Good to choice 67-70 60-64 CALIFORNIAN . . Red Brittle to dry hard Dry, rough Low I Fair to good ' 68-72 60-63 DANTZIC . . . . Red Soft, mild, to dry Sweet 1 Fair Good 68-71 60-63 KONIGSBERG . . Red ,, „ ,, 68-71 60-63 INDIAN, No. l(Hard Red Hard to flinty Dry, ricey Fair to good Fair to good , 68-72 62-66 Delhi) 61-64 „ No. 1 (Soft) Red Mild to dry hard Dry ,, „ 66-70 „ No. 2 (Mixed) Red - ” 66-70 60-63 SAMSOON (Asia Red Dry to brittle Low to fair Low to fair 66-70 60-63 Minor) 65-70 60-63 PERSIAN . . . . Red Brittle to hard MANCHURIAN . . Red Medium, hard ” Fair 65-70 56-62 MOLDAVIAN Red Dry to hard Dry or sweet i Fair to good Fair to good 68-7 2 60-64 Weight per bushel is for Imperial measure, and wheat supposed uncleaned as imported unless grossly mixed with coarse light refuse — then after a light screening only. The weights, flour yields, and losses in cleaning, as also the ordinary refuse contained in the different sorts, arc all to be taken as the fair average range. Russian samples admit of CHEMICAL COMPOSITION OF WHEAT. 289 FOREIGN REDS) — continued. IMPURITIE3 Present. General Remarks. Pro- Regular. Occasional. bable O' O Smut, seeds, oats. Peas, dirt, stone 3-6 The presence of frosted grain should induce cau- barley tion. Low yields. White maize, oats, Dirt, stone, smut 2-4 Excellent substitute for English. Decidedly weak seeds, peas in baking. Rye, seeds, dirt, Smut, barley, oats 2-3 The best all the year round wheats to fill place of screenings 2 3 American Springs. >> M 3-8 More waste than in No. 1 grades, and a lower flour 3-8 yield to be expected always. Rye,smut,dirt,seeds Barley, oats, stone 5-12 99 99 99 99 99 Excess of rye, smut, and seeds demands great care in working. Cockle, screenings, Smut, rye, oats. 2-6 When available a useful change for best Ghirkas. dirt barley 2-6 3-8 Cockle, rye, dirt, Smut, oats, barley Somewhat softer than Azimas and Ghirkas. Often seeds a better colour. Rye, seeds, dirt ,, ,, ,, 3-8 inferior to standard grades of Russian. 99 99 99 3-8 Now largely used to replace Azima and Ghirka. Tares, seeds, screen- Smut, oats, barley 2-4 Clean bright grain. Hard usually, and requires ings plenty of water. Tares, rye, smut. Dirt, oats, barley 3-8 Often difficult to clean satisfactorily owing to seeds large tares and other seeds. Screenings, barley. Stones, rye 3-8 Not a high grade, though useful cheap mixing sort. smut, dirt 99 99 3-8 Seeds and screen- Rye , oats, barley 1-4 Bright regular grain. Should be of maximum ings, dirt strength. , Black oats, barley. Smut, dirt 2-4 Long berried and fairly clean. Will produce very seeds white flour. Blach oats, barley. Dirt, stone 3-6 Variable as to waste and growm grain. Well 1 smut, seeds cleaned will work white. Oats, Barley Smut, seeds 2-6 Dry brittle variety very useful for replacing Ameri- can Winters or Ros Fe Plates. Black oats, barley. Smut, maize, dirt 2-5 Nearly as good quality as good Plate Barlettas seeds Short straws, oats. Dirt, stone, scented ; 2-5 1 Yields a characteristic yellow flour. As a rule barley seeds seeds very weak. Seeds, barley, oats Dirt, smut, rye 2-5 More akin to English in work than any other. I White flour. »» >> ,, ,, ,, 2-5 Generally as the Dantzic grades. Mild coloury wheat. Dirt, stone, seeds. Gram, oats, spice 3-6 Often large and good grain. Requires great care barley, peas 3-6 5-12 in cleaning and milling. » » " 99 99 99 Being under top grade, will call for greater care in 1 working. Dirt, stone, barley, ; Oats, peas, beans 4-12 I Variable as a rule ; needs extreme care in cleaning. seeds ,, ,, ,, >> »» >> 4-10 i Must be washed well to get full value from these hard wheats. Rye, seeds Barley, oats 3-8 Useful to replace any secondary reds of fair 2-6 ! strength. Tares, seeds, rye. Barley, oats, dirt At times will mill and bake very well. Heavy smut I 1 sound wheats. almost endless classification under names of ports — Berdianski, Novorrossisk, Ghenighesk, Marianople, Nicolaieff, Odessa, and many others. The general types are in all these instances Aziinas and Ghirkas, and the above analysis will therefore apply unless a new grade is specified. u 290 THE TECHNOLOGY OF BREAD -MAKING. The composition of the wheat at each stage is given in the following table : — Table showing the Proximate Composition of Wheat, in Per Cent. OF THE Total Dry Matter, at Fourteen Different Periods of Three Days each from the Setting of the Grain to Past Ripe- ness, THE Wheat being Gathered and Dried on the Straw. Groups. I. II. HI. IV. V. VI. VII. Ash * 4-81 4-16 3-24 2-52 2-16 2-07 1-82 Proteins 17-80 17-30 15-36 14-30 13-75 13-15 13-64 Amides 2-83 1-40 1-01 0-91 0-78 0-56 0-51 Fats 4-32 3-09 2-64 2-51 2-31 2-38 2-45 Crude Fibre . . 8-69 6-96 5-50 4-56 3-72 3-30 3-10 Pentosans ' 13-54 12-84 12-28 11-10 9-73 9-66 9-32 Dextrins 2-00 3-07 2-86 2-66 2-26 2-11 1-94 Sucrose. . 2-95 2-80 2-26 1-94 1-42 1-45 1-45 Glucose 1-55 0-64 0-17 0-08 007 0-05 0-05 Starch and Un- termined 41-51 47-74 54-68 59-42 63-80 65-27 65-72 Groups. VIII. IX. X. XI. XII. XIII. XIV. Ash 1-80 1-68 1-79 1-77 1-59 1-87 1-67 Proteins 14-55 15-40 16-24 14-96 16-59 16-56 17-26 Amides. . 0-50 0-44 0-50 0-44 0-61 0-62 0-56 Fats 2-59 2-60 2-44 2-50 2-37 2-46 2-52 Crude Fibre . . 3-11 3-01 3-03 3-04 2-98 3-00 2-96 Pentosans 8-82 8-50 8-41 8-08 8-16 8-33 8-63 Dextrins 1-75 1-72 1-83 2-46 1-77 1-79 1-75 Sucrose. . 1-43 1-28 1-44 1-52 1-51 1-53 1-50 Glucose Trace 0-01 Trace Trace Trace Trace Trace Starch and Un- determined . . 65-45 65-36 64-32 65-23 64-42 63-84 63-15 (Bull, 53, 1898, Arkansas Agric. Expt. Stn.) 429. Effect of Shade on Wheat Composition, Thatcher and Watkins. — As a result of comparative experiments made on the same wheat grown and ripened in sunshine and in shade respectively, Thatcher and Watkins find that the shaded wheat gives grains wRich are darker in colour. The protein is slightly higher and the starch lower than in the unshaded samples {Jour. Amer. Chem. Soc., 1907, 764). 430. Frosted Wheat, Shutt. — ^Shutt finds on analysis that the protein content of frosted wheat is considerably higher than that in the unfrosted mature grain. The effect of frost is a premature ripening, or rather drying- out of the grain, with as a consequence, a kernel high in protein, but low in starch (Jour. Amer. Chem. Soc., 1905, 368). CHAPTER XV. THE STRENGTH OF FLOUR. 431. Physical Properties of Flour. — In addition to its purely chemical composition, flour possesses certain physical properties which are of the highest importance to the baker, and consequently to the miller. These are “ Strength and “ Colour.” Flavour may also be mentioned, but this is essentially rather a matter of the palate than of chemical analysis, hence a judgment of the flavour of flour is best made by the actual con- sumer. These three properties of Strength, Colour, and Flavour, together with certain side issues connected with them, largely, if not entirely, deter- mine the commercial value of a sample of flour. 432. Nature of Strength. — There are certain desirable qualities in a bread-making flour which commonly go together. Among these are a large relative yield of bread due to a high water-absorbing capacity, the power of producing a large loaf, that of producing a bold loaf, and a well- piled loaf. In consequence of these usually, but not invariably, accom- panying each other, strength has been variously defined as the property of causing one or other of these effects. In the 1895 edition of this work the following occurs : — “ Strength. — This particular term is sometimes employed with different meanings by various handlers of flour. In former works by the author on this subject, he used it as meaning a measure of the water-absorbing power of the flour, and explained that the term ‘ Strength is also some- times used as the measure of the capacity of the flour for producing a well-risen loaf." In deference to the fact that its employment in this latter sense is the more general, the author also adopts the same defini- tion, especially as the term ‘ water-absorbing power " is very con- venient, and in itself explanatory. Strength, then, is defined as the measure of the capacity of the flour for producing a bold, large-volumed, well-risen, loaf. It is in this sense that the word is throughout used in the present work. Unfortunately at present there is no very satisfactory method of numerically registering strength except through a baking test, when the actual volume or girth of the loaf may be measured. Inferentially, the strength of a flour may be deduced from the character and quality of the gluten."" 433. Home-grown Wheat Committee’s Definition. — Humphries and Biffen, in a paper on “ The Improvement of English Wheat,” define their view of “ strength."" They dismiss those estimates which are based on measurements of water- absorbing power to produce a dough of standard consistency, remarking that bakers do not make the various kinds of flour up to one and the same consistency in the doughs. To give the best pos- sible loaves, some require to be made into “ tight,"" others into slack doughs, and the baker simply learns by experience what particular degree of con- sistency is the most suitable for the flour in hand. Number of loaves per sack is another common method (being a variant of water-absorbing power) . But some Russian and most Indian wheats give a large number of loaves 291 292 THE TECHNOLOGY OF BREAD-MAKING. but small and close of texture. This also is regarded as unsatisfactory. “ A third view, apparently largely adopted by the bakers, is to judge strength by the way a flour behaves in the doughs, by its toughness, elasticity, freedom from stickiness, etc. ; in other words, by the facility with which large masses of dough can be handled in the bakehouse. It seems more satisfactory to regard them as separate characteristics, for though of un* doubted importance to the baker, they are not necessarily associated with the production of satisfactory loaves. The fact that some of the Russian wheats from St. Petersburg or Reval are esteemed strong, but w^ork very badly in the doughs, will show' the necessity for this distinction.’' “ The deflnition finally adopted by the Committee [Home-growm Wheat Committee of the National Association of British and Irish Millers] is, that a strong wheat is one which yields flour capable of making large well-piled loaves, the latter qualification thus excludes those wheats pro- ducing large loaves w'hich do not rise satisfactorily. To estimate the strength of any particular sample of' wlieat then it is necessary to grind it and make the final tests in the bakehouse.” The baking tests w'ere carried out in the following manner : — “ In the first place the baking trials are made with sufficient flour to yield a batch of about half-a-dozen loaves — the ‘ cottage ’ shape being considered the most satisfactory. With each set to be tried, loaves are baked from flour whose quality has been accurately ascertained. To these standard loaves- a certain number of marks are assigned, and by comparison the baker records in marks his opinion of the strength of the flour under test. On this arbitrary scale the strongest wlieats in commerce mark about 100, ‘ London Households ’ 80 to 85, and average Engfish 60 to 65. The tests are always carried out by a man wlio devotes the whole of his time to this kind of w'ork, and repeated trials have shown that they may be rehed upon to express the strength with substantial accuracy ” (Jour. Agric. Science^ 1907, IL, 1). This definition of strength is in close agreement with that of one of the authors, previously quoted. In the one there is the expression “ well- risen,” and in the other “ w'ell-piled ” ; the latter term being employed to exclude large loaves which do not rise satisfactorily. A large loaf of coarse and ragged texture, and full of big holes, would not be regarded as either w'ell-risen or w'ell-piled. 434. Definition of Pile. — ^An explanation of the meaning attached to the w'ord “ pile ” may here be of service. It is stated on the authority of a w'ell-knowTi Scottish baker, that the baker’s use of the word originated in Scotland. Their very high close-packed loaves are smeared on the sides with melted lard before being placed in the oven. They are then easily pulled asunder, and the surface of the separated sides should have a smooth silky texture, a texture in fact recalling the “ pile ” of velvet. Such loaves are said to have a good pile, or to be w'ell-piled. A good pile is associated with the same fine evenness of texture throughout the interior of the loaf, and hence the term has acquired the secondary meaning of an even, finely vesiculated, and silky texture of the substance of the loaf. 435. Value of Baking Tests. — Any carefully devised method of making baking tests can scarcely fail to differentiate strong from w'eak flours. The difficulty is with those of intermediate and approximating character and quality, and here much must depend on the suitability of the method of working to the particular flour. To give an example of what is m.eant, suppose a baker of one district adopts a four hours’ system of fermentation, and another a six hours’ system. A flour wliich is just exactly ripe at the end of four hours would appear much stronger to the four hours’ baker THE STRENGTH OF FLOUR. 293 than to the latter. Conversely a six hours' flour would be relatively strong to the six hours' baker and weaker to the four hours' workman. An alter- native method would be to allow the fermentation to proceed to the best possible point for each particular flour and then bake it. This, however, introduces another element, in which there would almost certainly be con- siderable variations in judgment. As a result of variations such as these, it is probable that out of six baking experts no two would arrange a series of flours in quite the same order. Therefore, though Humphries' and Bif- fens' baking tests may be regarded as comparative among themselves, the reservation must always be borne in mind that there is no absolute and unvarying standard of strength. That flour is strongest which under the particular conditions of fermentation employed or required by any particu- lar baker or district best conforms to the definition previously given of strength. 436. Conditions requisite for Strength. — A loaf of bread consists of a baked aerated mass of elastic dough. The first requisite of a strong flour is that there must be a sufficiency of sugar or other material available for fermentation and consequent production of gas in the dough. As dough fermentation involves a series of changes in Avhich the distention by gas is but one, the source of gas must be sufficient for its continuous produc- tion, not only at the earher stages, but throughout the whole process, and essentially during that period in which the loaf is acquiring its final shape and volume ; that is to say, some little time before and after it is placed in the oven. Then next there must be some substance present in the flour which shall be capable of retaining a sufficiency of the gas generated in the dough, and elastic enough to be evenly distended by such gas. According to the kind of loaves to be made, the requirements for strength somewhat vary. If the bread is to be baked in a tin, it is supported on all its four sides, the top only being open ; the same holds good, though to a slightly lesser degree, in close-packed oven-bottom bread, where the loaves support each other. For bread of this kind, the dough may be very soft and even “ runny," provided it is elastic and of good gas-retaining capacity. But when the bread is baked into crusty loaves, whether of the cottage or Coburg type, the dough must not only be elastic and gas-retaining, but it must also possess sufficient rigidity to maintain its shape when standing alone and independently. Otherwise it may make a large but flat loaf, and not a bold well-risen one. The requisites necessary for strength under one of these sets of conditions are not precisely the same as in the other. It is generally recognized that the constituent of wiieaten flour in virtue of which its dough possesses these qualities of gas-retaining power and elasticity, is that known as gluten, that curious body largely composed of gliadin and glutenin. There must be sufficient gluten present to ade- quately retain gas and confer elasticity. Too much may be injurious, inasmuch as it may offer too great a resistance to the action of the distend- ing gas ; the consequence of this is the production of small and what are sometimes called “ gluten-bound " loaves. Further the gluten must be of the right quality, it must be sufficiently impermeable to gas ; it must be highly elastic, yielding readily to distention wdthout breaking, and yet it must be sufficiently rigid, particularly in the case of crusty loaves, to maintain a well-upstanding bold shape. Quantity and character of gluten may to a certain extent compensate each other. If the gluten is excep- tionally good, a little less of it may suffice, while slight deficiency in quality may be made up by a little extra in amount. Added to all this, important changes are going on in the gluten during the whole of the time of its fer- 294 THE TECHNOLOGY OF BREAD-MAKING. mentation. Normally, it is softening as fermentation proceeds, and becomes more yielding and gas-retaining during that operation. There comes a time, however, when the gas-retaining power is at its best, and further change s im ply injures and diminishes its tenacity. The art of the baker in part consists in so balancing all these various factors as to get the best possible result out of the flour with which he is working. 437. Research on Strength. — In view of the importance of this problem of strength, it has always received the keenest attention from those who have in any way made a study of bread-making. In particular, there has been an immense amount of work done in this direction during the past fifteen years, and especially since Osborne and Voorhees established de- finitely the composition and properties of the proteins of flour. The investi- gations referred to have been made by eminent scientists in conjunction vdth advanced manufacturers in both America and Europe including this country. There seems no adequate method of presenting the results to the students of bread-making other than by giving a resume of the work that has been done, followed by a summary of the conclusions which may at this stage be formed. Probably the best and simplest way will be to arrange the abstracts of such research work in chronological order. 438. Knowledge in 1895. — As a starting point, the following paragraphs on the effect of each leading constituent of wheat are quoted from the 1895 edition of this work. When originally prepared they were intended as a summary of the general knowledge at that time. “ Fat. — As far as is at present known, the quantity of fat in wheat is not a very important element in determining its value.^ Fat is of course an important food stuff, and as such is of service. The germ of flour contains a very high percentage of fat, and when removed must necessarily lessen the percentage of this body present. Starch. — This makes up the principal part of the grain, and in the analyses given varies from 63*71 to 67*88 in the different wheats. In these analyses the starch was probably determined by difference ; that is, the percentage of the other constituents was subtracted from 100, and the remainder considered to be starch : the quantity of starch will therefore naturally be the complement of the other bodies rising when they fall and falling when they rise. Starch is of course of great importance as being the principal food-stuff of bread : in sound wheat the starch granules are whole, while in wheat which has sprouted, or heated unduly through damp, the starch granules are pitted, and often fissured. The result is that their contents become more or less changed into dextrin and sugar. Cellulose. — This substance is of considerable service to the plant ; but to the miller it has no value, as being useless as an article of food, he endeavours to keep it out of the flour. As the cellulose is found principally in the bran, the thinner skmned wheats will yield, on analysis, less cellulose. Judgmg the cellulose alone, the less quantity present the better is the wheat. Dextrin and Sugar. — Dextrin exists in sound wheat in but small quantity ; but when hydrolysis of the starch has set in, the percentage may considerably increase : in wheats or flours the presence of large^ quantities of dextrin would be decidedly objectionable. Sugar is. always present to a slight extent in wheat. Bell states that the sugar- ^ See Fatty Matters and Acidity of Flour, paragraph 498. THE STRENGTH OF FLOUR. 295 “ corresponds in properties to cane sugar, as it does not reduce Fehling’s solution, but may be readily inverted by sulphuric acid. Bell extracts the sugar vitli 70 per cent, alcohol, and so prevents any action on the sugar by the proteins. The author finds that on extraction with water the sugar invariably produces more or less precipitate with Fehling’s solution ; the amount of precipitate being increased by treatment vith sulphuric or hydrochloric acid. Paragraph 370, chapter XI., gives some results of sugar determinations in the aqueous extract of flour. The explanation of these results seems to be that, in perfectly sound wheat or flour, small quantities of cane sugar, only, exist. In ansound wheats or flour, in which the starch has been subjected to diastasis, maltose may also be detected. Wanklyn makes the useful suggestion that estimations of sugar should be made in both aqueous and alcoholic extracts : unsoundness in flour would be indicated by the presence of an increased amount of maltose in the alcoholic extract. Assuming the correctness of Bell's statement that sound wheat sugar does not reduce Fehling's solution, an alcoholic extract of sound wheat should give no precipitate with that reagent. Any maltose therefore in an alcoholic extract is the measure of diastasis of the starch of the grain that had occurred previous to analysis. If the flour be then mixed with water, and allowed to stand for a definite time, and then the maltose estimated in the aqueous extract, the difference be- tween the amount obtained in this estimation and the former one would be a measure of the quantity of soluble starch, arising from fissured granules, present in the flour. A series of comparative estimations of this kind would be of service. As the sugar of a flour affords the saccharine body necessary in fer- mentation, the presence of this compound in small quantity may be tolerated, but as before pointed out, it should consist principally of cane sugar, the presence of much maltose being evidence of unsoundness. Soluble Proteins. — In technical wheat analysis no attempt is made to separate the albumin from the globulin. In the following analyses these bodies are estimated in a portion of the aqueous extract of the flour, by either what is known as the albuminoid ammonia process, or by Kjeldahl's process ; of which latter, in common with other analytic methods, a description is given hereafter. As has been already stated, these bodies have a serious action on starch, and also on gluten ; under the influence of yeast, during fermentation, they act on the starch and convert that body into dextrin and maltose. In the para- graph on artificial diastase. No. 267, this action is somewhat fully de- scribed. A relatively low percentage of soluble proteins is usually to be preferred as indicating soundness both in flours and wheats. In the case of wheat it is somewhat difficult to form a judgment, because the bran and germ contain considerable quantities of soluble proteins ; as these are removed in the operation of milling the proportion differs somewhat in the wheat from that in the dressed flour. It is in damp years and wet climates that inferior wheats are grown ; the excess of moisture, and lack of warm, dry sunshine, leave the grain damp, and also leave the proteins in the soluble condition, instead of thoroughly ripening the grain, and thus causing them to assume the insoluble form. From time to time attention has been directed to the problem of artificially drying wheats. With some samples of wheat this is prac- tically a necessity, as otherwise they are absolutely unfitted for flour producing purposes. A gentle kiln-drying at a temperature of from 100° to 120° F., by driving off the excess of water, arrests its degrading 296 THE TECHNOLOGY OF BREAD-MAKING. “ action on the gluten, and causes the wheat to yield a sounder and stronger flour. The drying is necessarily accompanied by loss of weight ; against this must, however, be set the improved quahty of the flour. In connection Avith this, attention is directed to the para- graph on artificially drying wheats and flours, in the next chapter. Soluble Extract. — In the following analyses by the author the percentage of ‘ soluble extract ' is in most cases given. This repre- sents the proportion of the wheat or flour soluble in cold water. The sample is continuously shaken up with water for five minutes, allowed to settle for the remainder of half an hour, then filtered from the sohd matter, the clear liquid evaporated, dried at 100° C. (212° F.) and weighed. This extract consists of soluble proteins, sugar and dex- trin, and potassium phosphate. Considerable importance attaches to the amount of soluble extract, as being the measure of the amount of degradation of the gluten and starch of the wheat or flour ; conse- quently an excess of soluble extract indicates unsoundness. On the other hand, a very low percentage of sugar in a flour or wheat is accom- panied by an absence of that sweetness characteristic of the best flavoured wheats and flours. Insoluble Proteins, Gluten. — The insoluble proteins are, for practical purposes, estimated by doughing the flour, and washing away the starch, leaving behind the tough and elastic gluten. The gluten of wheat is of great importance, as being that constituent which imparts to wheaten flour its remarkable property of rising into a light and spongy loaf. The gluten is usually weighed both in the moist or wet state, and also when dry ; it weighs from 2*7 to 3 times as much when moist as dry. As the gluten of wheat is that constituent which causes the flour to be a strong flour, wheats to be of high quality should con- tain a high percentage of gluten. This, how^ever, is not of itself suffi- cient ; the glutens of different wheats vary not only in quantity but in quahty — some glutens are tough and elastic, others are soft and ‘ rotten." These latter yield weak flours, and consequently bread which is not well risen ; further, the quantity of water they are capable of retaining is but small. They as a result produce a comparative low number of loaves from a sack of the flour. The gluten then should not only be present in considerable quantity, but should also be highly elastic. Between the amount of gluten and of soluble proteins in a wheat a close relation exists. With an increase of total proteins, both the soluble and insoluble varieties will simultaneously rise in amount. In interpreting analytical results, high soluble proteins should not be considered alone — they are the natural concomitants of high total proteins and gluten. But where the soluble proteins are high, and the gluten low, then distinct evidence of a low grade or unsound wheat is afforded. The aleurometer is an instrument designed for the purpose of estimat- ing the elasticity of gluten ; the higher the figures obtained by its use, the more elastic the gluten is supposed to be. ‘ True Gluten.’ — It is difficult, and in many cases impossible, to wash away the whole of the starch from flour or wheat meal without also washing away some of the more soluble parts of the gluten itself. In consequence, gluten determinations will vary according to the thor- oughness of the washing, and this differs in different hands. As a clieck, therefore, on gluten determinations in cases of importance. THE STRENGTH OF FLOUR. 297 “ the author advises the making of a nitrogen estimation on the dried gluten, and deducing therefrom the amount of protein it contains ; this latter, being calculated as a percentage on the whole wheat or flour, is denominated percentage of ‘ true " gluten. The amount should be at least 80 per cent, of the crude dry gluten. With even considerable differences between percentages of crude gluten, the amounts of true gluten agree very closely. In the further chapters on flour, data of various estimations are given. Gliadin. — ^The estimations of proteins soluble in 80 per cent, alcohol are practically, in the case of wheat and wheaten flour, estimations of gliadin. As affording evidence of the quality of gluten, gliadin estimations may possibly prove of value. It is probable that soft, ductile, tenacious glutens may contain a high percentage of gliadin, but a sufficient number of estimations has not as yet been made to permit the drawing of any deflnite conclusions. Ash. — This gives the quantity of mineral matter present in a wheat or flour ; the ash consists principally of potassium phosphate, a sub- stance of considerable value from a nutritive point of view ; the mineral matter of wheat is contained principally in the bran. Water. — ^The water of wheat is found to be mostly associated with the starch of the grain ; that body is extremely hygroscopic, and can only be obtained actually free from water by prolonged and careful drying. The quantity of water in flour and wheat does not vary vdthin very wide limits, the highest percentage being about 15, and the lowest about 8 per cent. The question of importance is the influence of the water on the quahty of the grain or flour, and the interpretation to be placed on such results as are here given. As may readily be supposed, a wheat that is grown either in a naturally damp climate, or during an unusually wet season, contains more water than one grown under the opposite conditions. Taken into consideration without reference to the other constituents of the grain, a large proportion of water is to be deprecated, for the very simple reason that water is scarcely worth purchasing at the price given for wheat or flour. This, however, is not the only objection to the presence of a large percentage of water ; a much more serious objection is based on the fact that such high propor- tions show that the wheat is unsound, and that in all probabihty the other constituents will not be of the most promising character. In the first place, damp wheats and flours favour the development of those organisms which produce mustiness and acidity. In the presence of excess of moisture, too, the gluten of flour is rendered soluble in part, and also loses its elasticity. Further, more or less of the starch will be found to have been degraded into dextrin and maltose by diastasis. Valuation of Gluten — A number of attempts have been made to satisfactorily determine the quality of gluten, as considered apart from its actual percentage ; it must be confessed, however, that the results obtained have been, from the standpoint of commercial testing, some- what disappointing. As a result of experience in gluten testing, a judgment can be formed from the feel and appearance of the gluten when wet. Some glutens are soft and sticky, possessing at the same time but little or no toughness. Others, again, are highly elastic, and firm and springy to the touch ; these latter are special qualities which render a flour of value for bread-making purposes. The Aleurometer . — The instrument knowm as the aleurometer is the result of one attempt to measure these qualities of gluten. The 298 THE TECHNOLOGY OF BREAD-MAKING. “ principle is that of measuring the degree of expansion of the wet gluten on being maintained for som^e time at a temperature of 150° C. A small cylinder is provided, to which is attached by bayonet catches a bottom and top ; through the latter of these passes a graduated piston rod, fixed in its turn to a piston sliding within the cylinder. A weighed quantity of gluten is placed in the cylinder, and the whole apparatus put in a hot oil or glycerin bath, maintained at 150° C. The gluten expands with the heat, and raises the piston, its maximum expansion being read on the piston rod. This instrument certainly divides the glutens of flour and wheat into strong and weak classes, but no very fine lines of distinction can with accuracy be drawn. True Gluten . — The value of estimations of true gluten as a check on those of crude gluten has already been indicated ; but they have also an additional importance. Suppose, for example, two flours each yield 35*0 per cent, of wet gluten. One is hard, elastic and springy, while the other is soft and flabby, and causes the washing water to become ‘ lathery.' It will at once be said that the former is the higher quality gluten of the two, and quite correctly : but, further, the results would be entered that each yielded the same quantity of gluten. This latter deduction is not all the truth, for in the former case hardness of the gluten will have permitted most of the starch to be entirely eliminated with the least possible loss of real gluten constituents. In the second instance the gluten will have begun to wash away while yet there is a considerable quantity of starch remaining. Therefore the 35*0 per cent, in the first case will contain more real gluten and less foreign matter than in the second. The estimation of ‘ true gluten ' by a nitrogen determination will show that in No. I there is a higher per- centage of actual gluten protein matter than in No. 2, and that there- fore the weaker character of the second flour is due not only to inferior quality of gluten, but also in part at least to a lower percentage of true gluten. Gliadin Determinations . — It has already been sliovn that gluten consists of two protein bodies knowui as gliadin and glutenin, and that the former of these, which is soluble in 80 per cent, alcohol, acts as the binding and toughening agent in gluten. In a following chapter an account is given of percentages of protein in alcoholic extracts of flours ; as the protein thus extracted consists almost entirely of gliadin, some light is thrown on its effect on the particular character and quality of the flours discussed. Viscometric Gluten Valuations . — It being an accepted fact that the characteristic elasticity of wheaten flour is due to the quantity and quality of gluten, we are confronted with the following problem : — If a spring American flour be taken which yields 46*25 per cent, of 'wet gluten, and has a viscometer value of 67 quarts per sack, it may be compared with a winter American flour containing 27*93 per cent, of wet gluten, and having a viscometer value of 54*5 quarts per sack. Is the difference in absorptive power as registered by the viscometer due entirely to the different quantity of gluten present or partly to the quality of that gluten ? As an attempt to solve this question, various flours "were taken, and their gluten and viscometer readings determined. The dry flours were then mixed with different quantities of pure wheat starch until they all yielded the same percentages of gluten ; visco- metric determinations were then made on these mixtures. The folio 'sw- ing table gives the results of such tests : — THE STRENGTH OF FLOUR. 299 “ Viscometer Determinations on Mixtures of Flour and Starch. 1. Spring Ameri- can Patent. II. Winter Ameri- can Patent. III. Second Class Winter Ameri- can Bakers. IV. Hun- garian Patent. V. English Wheat Patent. VI. British MUled First Patent. VII. British MiUed Second Patent. Original Percentage of Wet Gluten 39-2 1 28-2 i 1 320 350 27-75! 31-9 38-4 Water-absorbing Power by Viscometer . , . . ■ 68-6 i 54-8 690 76-0 61-0 60-5 64-0 Viscometer Readings, on Gluten being reduced by admixture of Starch to 35 per cent. 65-0 30 „ 62-7 1 1 7’l’3 60-0 63-0 25 „ 620 : 55-5 66*0 70-7 59-5 20 „ Weight of Starch added to 100 parts of Flour to reduce Gluten to 20 per cent. 61-4 55-4 620 66-0 57-5 5*7-5 58*5 960 41-0 600 75-0 38-75 59-5 92-0 It will be seen that in the case of the flours with high water-absorbing capacity, they still retain that property on being diluted with starch to an uniform wet gluten-percentage level. Therefore, so far as wet gluten is concerned, it is evident that not merely quantity but also quahty has a direct influence on the water-absorbing capacity of the flour. The calculation of how much starch has to be added is a very simple one, and is best illustrated by an actual example : thus, taking the first flour in the table, we And it yielded 39*2 per cent, of wet gluten. If 100 parts yield 39*2 per cent., how much starch must be added to reduce the percentage to 20 on the mixture ? As 20 : 39*2 : : 100 = 1 : 39*2 : : 5 = 39*2 X 5 = 196*0, weight of mixture. 196 — 100 = 96, weight of starch to be added. This calculation resolves itself into the simple one : (Weight of wet gluten X 5) — 100 = weight of starch to be added. In connection with the stronger flours, an interesting point is the bearing these experiments have on their capacity for mixing purposes. Such flours are largely employed in connection with weaker flours Avhich, while used for colour and flavour, are more allied to starch in strength properties. Evidence is here given of the comparative capacity these various flours have of bearing such admixture. In view of the importance of true gluten estimations as a control on those of wet gluten, a series of determinations made on flours diluted with starch to an uniform true gluten basis would be of interest. Estimation of Proteins Soluble in Alcohol. — The albumins and globulins of flour are soluble in water and insoluble in alcohol ; gliadin is insoluble in water, but soluble in 80 per cent, spirit ; while glutenin is insoluble in both reagents : it is therefore possible to make a proxi- mate analysis of the proteins of flour by determining proteins soluble in water, proteins soluble in 80 per cent, alcohol, and total proteins. Proteins soluble in alcohol may be determined in the follovung manner : 300 THE TECHNOLOGY OF BREAD-MAKING. “ To 10 grams of the flour in a flask add 100 c.c. of 80 per cent, alcohol, and shake up thoroughly : weigh the flask and contents on the balance, and then raise the alcohol to boiling point by immersion of the flask in a hot-water bath. Take out, re-weigh, and if necessary make up, loss of weight by adding a few drops more alcohol. Cork up and shake vigorously several times while warm. Let the flask stand over night, shake again in the morning, allow to settle and Alter. Take 20 c.c. of the flltrate in an acid flask, evaporate to dryness, and determine proteins in the usual manner. Twenty c.c will contain the proteins soluble in alcohol of 2 grams of the flour. The following table contains the result of a number of estimations made in this manner, except that the alcoholic solution was Altered hot. The results are compara- tive among themselves, but subsequent investigation shows that more than the gliadin proper is held in solution by the hot alcohol : — Proximate Analysis of Proteins in Flour. Flour. Proteins. Dry Gluten. Total. Soluble in Water, Globulin, etc. Soluble in Alcohol, Gliadin. Insoluble. Glutenin, 1 . Spring Patent 2. Spring Bakers . . . . 3. Winter Patent . . . . 4. Winter Bakers . . . . 5. English Wheat Patent 6. Hungarian Patent . . . . ! 12-64 14-95 8-77 10-86 8-78 11-53 2-60 1-58 1-45 1-31 1-38 1-47 i 4-81 6-08 3- 63 4- 43 4- 33 5- 27 5-23 7-29 3-69 5-12 3- 07 i 4- 79 13- 05 14- 99 8- 89 11-00 9- 15 11-45 The above table gives the percentage of albumin and globulin, and also the gliadin : the glutenin may be obtained by difference, and is given in the fourth column. The few analyses made do not afford suffi- cient evidence on which to generalise : as might be expected from its soft, tenacious gluten, the Hungarian Patent contains a very high pro- portion of gliadin. But the Spring Bakers , which is as different a flour as one can well conceive, contains still more gliadin. On the other hand, the English Wheat Patent, also a totally different flour, contains more gliadin in proportion to its glutenin than does the Hungarian flour. So far as percentages of gliadin and glutenin are concerned, the Hungarian flour can be reduced to the same condition as the English by dilu- tion with starch ; but as shovn above (page 298, Viscometric Gluten Valuations), such diluted Hungarian flour behaves altogether differently to English flour. Further experiments on this point are necessary before absolute conclusions can be drawn. More analytic data must first be accumulated, and then an interesting research should be made on the lines of adding gliadin and glutenin respectively to different flours, and studying how far such additions modified their characteristics. It would be necessary at first, of course, to determine whether or not the processes themselves, employed for the extraction of these proteins from flour, altered their essential properties.’’ 439. Gliadin and Glutenin Estimations, Guthrie.— In June, 1896, Guthrie made a communication on the above subject to the Royal Society of N.S. Wales. He therein adopts the power of absorbing water as his definition of strength and uses the term in that sense. His strength results are ex- pressed in quarts of water absorbed by a sack of 200 lbs. The gluten was THE STRENGTH OF FLOUR, 301 O o Ol CO CO p p p 00 CO o CO 'tH G (6 CO 0 1 (N O 1 CO o (N o . 1 o 1 o CO o 1 CO 0 1 o o o o o o 0 0 i-H I-H c "c .£ S (M 3^ 1 t;- 1 p op 1 (M 1 uo r-H 1 o lO UO 1 G 1 G f^-£o 2 (M (M Th (M CO (M (M CO g oil GO CO p p 1 00 1 LO c: 1 6 4l 1 1 (Cl 1 « ^^3 c o o !>• CO _g o lO o UO o CO 0 1 1 Ol tH 1 00 CO p 1 CO 1 p O CO o (N 3h CO 1 CO 1 CO C CO Tt^ 1— t (Cl I-H ■2 1 1 Ci (M 1 Cl 1 CO o 1 00 1 p :3 GO o Ci cb GO Cl 1 op 1 10 o CO o uo o (M o 1— lO 1— 1 Cl 10 (Cl o (M . 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S 13 " ffi ^ ’S 0 § © '4H 0 m ^ tL ci lO Tt( o o TtH o CO Tt( CO CO Tf( UO ^ .S 1 o S i CO 1 o C5 o o Gi C: c: Cl Cl Cl Cl (Cl Cl Cl GO 00 GO GO 00 cc 00 GO 00 00 00 00 00 00 o r— 1 4-H ,-H I-H P Pj ;4i © ^ 1 s :: 'S 'o - - o p^ © c >s 1:3 P c .2 J, ■*2i - > ■i p :; '0 ;h © Ch 02 P2 p '' g *C G o 0 c3 H < H ffi pq 302 THE TECHNOLOGY OF BREAD-MAKING. extracted, by careful and thorough washing, from a number of flours, and then determinations of the glutenin and gliadin in the gluten were made according to the method adopted by Osborne and Voorhees. Fifty grams of flour were made into a dough with water, and allowed to stand for one hour, the gluten was then extracted and weighed. The still moist gluten was then cut up into very small pieces and introduced into a flask contain- ing 300 c.c. of 70 per cent, alcohol. The extraction of the gliadin was con- tinued for four and a half days, the alcohol being replaced by fresh and measured quantities at stated times, so that all the glutens should undergo exactly the same treatment. The alcoholic solutions of the gliadin were evaporated to dryness and the gliadin dried at 100° to constant weight. The insoluble glutenin was introduced into a weighed dish, washed once with alcohol and three times with ether, and dried at 100° to constant weight. The foregoing table shows the results obtained : — Guthrie draws the following conclusions from these experiments : — The strength or water- absorbing capacity of a flour depends directly upon the relative proportion in which the two proteins are present in the gluten. If the gluten contents of two flours be nearly the same, that will be the stronger flour which contains the larger proportion of glutenin. Flours in wLich glutenin preponderates yield strong, tough, elastic, non- adhesive glutens. Increased gliadin content produces a weak, sticky, and inelastic gluten (Agricultural Gazette, N.S. Wales, September, 1896). 44-0. Gliadin and Glutenin Estimations, Fleurent. — In August, 1896, a paper by Fleurent was published, in which he stated that he regards the differences in properties of different flours as being clearly marked by corre- sponding variations in the relative proportions of glutenin and gliadin present in the flour, and suggests the following method of examination. Gluten is washed out in the usual manner from 33*33 grams of flour. The mass is cut into small pieces, and treated in a stoppered bottle vdth 80 c.c. of alcoholic potash (3 grams of KHO per litre of 70 per cent, alcohol). In order to aid the solution, a quantity of glass beads is also added, and the whole shaken at intervals until complete solution has been effected, which usually takes from 36-48 hours. A current of carbon dioxide is next passed through the liquid until complete saturation is effected, the potash being by this means converted into the carbonate or acid carbonate. The liquid is next transferred to a graduated flask and made up to 110 c.c. by the addition of water. The liquid is briskly mixed and 20 c.c. drawn off, before the solid matters have had time to settle, and transferred to a tared dish. On drying and weighing the residue, the quantity found, less the K2CO3 pre- sent, represents the total gluten. Another portion of the liquid is Altered to remove the insoluble glutenin, and 20 c.c. of the flltrate evaporated, dried and weighed, in order to determine the gliadin. The difference between the gluten and gliadin represents the glutenin. In case of flours containing 9 per cent, of gluten or over, it is recommended to use 150 c.c. of alcoholic potash and make up the treated solution to 200 c.c. On subjecting a num- ber of flours to this mode of examination, Fleurent arrived at the following conclusions : — I. Ignoring the actual percentage of gluten, the proportions of glutenin and gliadin wliich are found in flours giving the best bread-making results are glutenin, 25 per cent. ; gliadin, 75 per cent, (ratio, 1:3). II. Flour in which the ratio of glutenin to gliadin is 1 : 4, develops well during fermentation ; but the dough again collapses and becomes compact during baking. With such flour, the proportion of water normally em- ployed must be reduced. THE STRENGTH OF FLOUR. 303 III. When the ratio of glutenin to gliadin rises to 1 : 2, the flour becomes almost unworkable ; the dough does not develop either during fermenta- tion or baking, and the bread remains solid and indigestible. IV. A comparison between bread baked from flour conforming to the standard laid down under I, and that produced from flour varying 2 per cent, either way from the typical value, reveals differences that are readily perceived by an expert {Comptes Rend., 1896, 123, 755). The method adopted consisted in first dissolving the whole of the gluten, and then removing the potash by its conversion into carbonate, potassium carbonate being insoluble in strong alcohol. On repeating FleurenUs method, one of the authors finds that with alcohol of only 70 per cent, strength, the potassium carbonate is not entirely insoluble. In consequence it would be expected that the glutenin would partly remain in solution. In fact, Fleurent's proportions of gliadin are considerably higher than those of most other chemists. 441. Identity of Proteose and Gliadin, Teller. — ^Por some time there had been discussion between Teller and Osborne as to the nature of pro- teose. A reference to paragraph 218 will show Osborne’s method of extract- ing proteose. Teller sums up his conclusions as follows : The properties of gliadin are such that we would expect to find, in the very situation in which they found their “ Proteose,” small quantities of a body having proteose reactions, and that no distinguishing characteristic or reactions between that “ Proteose ” and gliadin is known. The proteins of wheat are, then, four : Edestin, Leucosin, Gliadin, Glutenin. Of these edestin and leucosin are readily soluble in dilute solutions of common salt, but are insoluble in dilute alcohol ; gliadin is slightly soluble in dilute salt solutions and is readily soluble in hot dilute alcohol, while glutenin is insoluble in both of these liquids. Teller further investigated the extent to which the degree of solubility of gliadin is affected by the strength of the alcohol used as a solvent. For this purpose, extracts were made on the same wheat meal with alcohols ranging from 40 to 95 per cent, in strength, there being a difference of 5 per cent, of alcohol between each solvent and the next stronger. The results were as given, the nitrogen in the extracts being computed to per cent, on the one gram of wheat used. strength of Alcohol in Per Cent. Per Cent. Nitrogen in Extract. strength of Alcohol 1 in Per Cent. Per Cent. Nitrogen in Extract. 95 0-21 65 1-30 90 0-31 60 1-38 85 0-61 55 1-40 80 0-89 50 140 75 1-08 45 1 40 70 1 M8 1 40 1 40 i Accordingly alcohol of the specific gravity of 0*90 strength, 57*05 per cent, of alcohol by weight, has been adopted by him for this solvent {Agric. Expt. Station, Arkansas, Bull., No. 53, September, 1898). 442. Gliadin and Glutenin Estimations, Guess. — In 1600, Guess made a number of estimations of these bodies in flour, and reported the results. He determined gliadin and glutenin, and assumed there were present in the samples ghadin, glutenin, edestin, leucosin and amides. 304 THE TECHNOLOGY OF BREAD-MAKING. Amides were determined separately by extraction of 5 grams \\dth one per cent, salt solution in 250 c.c. flask, salt solution was added to mark, shaken at intervals for an hour, allowed to stand for two hours, filtered. In 100 c.c. of filtrate, the proteins were separated by a few c.c. of 10 per cent, solu- tion of phospho- tungstic acid, filtrated, 50 c.c. of the filtrate evaporated with sulphuric acid, and the amide nitrogen determined. Gliadin . — One gram of the sample w^as digested with 100 c.c. of alcohol of 0*90 sp. gr. (57*0 per cent.), maintained just below alcohol boiling point for one hour, being shaken at intervals of ten minutes. Allowed to settle for one hour and decanted into a flask, avoiding carrying over any turbidity. The residue was washed three times with 25 c.c. hot alcohol, allowing to settle for twenty minutes between each operation, and the washings added to the main portion of solution. The alcohol is distilled off and nitrogen determined in residue, the amide nitrogen is substracted and the remainder calculated as gliadin (N X 5*7). Glutenin . — The residue of the flour from the gliadin extraction is after cooling treated with 250 c.c. by 1 per cent, salt solution, shaken, allowed to settle for an hour, and filtered ; 250 c.c. more salt solution are added, again shaken at intervals during one hour, allowed to settle for two hours, and filtered through the same Alter. The Alter and residue in the flask are together evaporated to dryness, nitrogen determined and calculated as glutenin. Guess finds that the elastic quality of the gluten was improved as the ratio of gliadin to glutenin increased, and reached no limit beyond wLich an increase in gliadin w-as harmful. He suggests as a valuing factor the percentage of gluten X ratio of gliadin to glutenin. The following are a few' of his results : — Flour. Grade. Gliadin Per Cent. Glutenin Per Cent. Ratio of Gliadin to Glutenin. Gluten X Ratio, j Keew'atin Patent 813 2-24 3-62 37-54 Bakers’ 8-47 3-90 217 26-84 Portage Patent 8-4 21 4-0 42-00 Bakers’ 8-65 2-6 3-32 37-25 Ogilvie’s Patent 8*04 2-92 2-76 30-24 5 ? • • Bakers’ 74 3-6 2*05 22-55 Hungarian Best . . 9-38 2-80 3*35 40-80 The wiiole of these flours except the last w^ere of Canadian manufacture. It will be noticed that the percentage of gliadin runs from 2*17 to 4*0 times as much as that of glutenin {Jour. Amer. Chem. Soc., 1900, 263). Amides are first determined in order to make the necessary corrections on gliadin, as they also are soluble in alcohol of the strength employed. It will be noticed that the gliadin is filtered and washed out hot. After extracting the residual flour with salt solution, the remaining protein is assumed to be glutenin. Contrary to Fleurent, Guess found without any limit that the more gliadin there w'as present the more elastic and better was the gluten. His valuing factor is based on the view that a flour is improved both by the amount of gluten and also the height of the ratio of gliadin. His factor therefore embraces the both of these. Examination of his results show's that they run fairly closely to those of Fleurent, not- withstanding that their methods of analysis w'ere very different. 443. Rapid Gliadin Estimations, Fleurent. — In HOI, Fleurent suggested or the purpose of rapidly determining with approximate correctness the THE STRENGTH OF FLOUR. 305 proportion of gliadin present in a flour the use of a specially graduated densimeter (hydrometer). The instrument is furnished with two scales reckoned from the same zero. The upper is for the purpose of measuring the density of alcohol, so as to have it of a density corresponding to 74 per cent, strength. The low'er is for measuring the density of the gliadin solution obtained from the flour by means of this 74 per cent, alcohol. The dry gluten of the flour must be previously determined, and then a quantity is taken wiiicli contains 5 grams of dry gluten. To this is added 150 c.c. of the 74 per cent, alcohol, and the mixture shaken and allow^ed to stand for some time. The density is then observed and is read off into amount or percentage of gliadin by means of a table of densities compiled from those of flours in wLich the gliadin has been directly determined. Fleurent states that variations in the gliadin from different flours, in the amount of other substances dissolved, and in the humidity of the flours, do not affect the results to an extent appreciable for the purposes of the baker {Comptes Rend., 1901, 122, 1421). It wall be observed that these determinations are to be made direct on the flour, and in the cold. The principle is that of estimating gliadin by the density of its solution. 444. Effect of .Varying Proportions of Starch on Fiour, Snyder. — In 1901, Snyder published the results of some experiments on the quality of bread as affected by increasing and diminishing the proportion of starch in the flour. Quantities of starch, equal to 10 and 20 per cent, respectively, w^ere added to a strong flour containing 12 per cent, of protein. Baking tests (tin loaves) w^ere made on the mixtures, and as a result the WTiter arrived at the conclusion that wheat starch may be added to a flour of this kind to the extent of 20 per cent, without materially diminishing the expansion of the dough, and consequently decreasing the size of the loaf. The effect of increasing the proportion of starch was to lessen the water- absorbing capacity of the flouf.'^ Converse experiments were made in which the pro- portion of gluten w^as increased, or more strictly that of starch w^as diminished by removing some of the starch from the flour. The bread made from the flour, having a low starch content and a correspondingly high gluten content, w^as, in appearance, in every respect hke normal bread. The size of the loaf was not materially affected. Therefore it is the character rather than the quantity of the gluten content w4iich govern the quality of the bread {U.S. Dept, of Agric. Bull., 101, 56). These results agree with the conclusions derived from the viscometer determinations on mixtures of flour and starch, page 298. 445. Gluten Determination, Arpin. — The abstract of a description of Arpin's method of determining gluten is prefaced by the somewhat curious remark that “ although there are numerous sources of error in the separa- tion of the gluten, the valuation of a flour on the basis of its content in moist gluten has not yet been suppressed.’" Arpin uses a somewhat large quantity of flour for his determinations, 33*33 grams, and apparently w ashes out the gluten immediately on making the dough. After w'eighing, he then dries for ten minutes at 120°-130° C., cuts it up and dries for ten hours at 105° C., to constant w^eight. He points out that the yield of gluten is increased with an increase in the temperature of the w^ater used ; presum- ably for washing). With the same flour he obtained the following results : — • Temperature of w'ater .. .. .. 5° C. 15° C. 25° C. Moist Gluten, per cent. . . . . . . 23*98 25*26 26*42 Dry Gluten „ 7*83 8*08 9*24 In a subsequent communication, Arpin refers to Balland’s statement that the yield of moist gluten increases with the time the dough is allowed X f 306 THE TECHNOLOGY OF BREAD-MAKING. to stand before kneading. This is confirmed by an experiment of his in which as a result of allowing the dough to stand for four hours the yield of moist gluten was increased by 1*66 per cent., that of the dry gluten remain- ing unaltered. The increase is simply due to the water- absorbing power of the gluten having become higher by standing. Another interesting point is that the yield of gluten increases with the hardness of the water used, this increase in certain experiments amounting to 4*7 per cent, of the amount of dry gluten {Jour. Soc. Chem. Ind., 1902, 1417 and 1560, abstracted from Chem. Centr., 1902, 2, 1019 and 1347). The connection between an increased yield of gluten and hardness of water has an intimate relation to the solubility of ghadin in pure water, and also may be borne in mind when subsequently studying the results of Wood’s researches. 445. Fermentation of Dough, Parenti. — This chemist made analyses of flour, and of dough prepared therefrom, both before and after fermentation. The quantity of starch and of dextrin was found to have suffered no altera- tion by fermentation, but the reducing sugar was reduced to a trace or to nil (from 2*31 to 0*13 per cent, was the average reduction in four experi- ments). The amount of the substances precipitable by alcohol increased, however, from 2*86 to 4*15 per cent, on an average. Parenti found him- self unable to obtain any gluten by washing the fermented dough. He regards his results as confirming those of Boutroux, whose view is that panary fermentation consists chiefly in the alcoholic fermentation of the sugar in the flour by the yeast added, and in a conversion of the gluten, which, in breaking up, produces soluble proteins. The origin of this con- version he finds, not in the yeast, but in an enzyme contained in the flour {Boll. Chim. farmae., 1903, 42, 353). Parenti’s results and conclusions should be compared with those given in paragraph 466, in which the fermented dough was kneaded until free from gas before washing out the gluten. Under those circumstances a consider- able amount of gluten is recoverable from the dough even after excessive fermentation. 446. Polarimetric Estimation of Gliadin, Snyder. — Snyder quotes the following method of Osborne and Voorhees for the determination of gliadin direct on flour. Five grams of the flour are w^eighed into a flask, and 250 c.c. of 70 per cent, alcohol added ; the flask is shaken at half-hour intervals for three hours. After twelve to eighteen hours the alcohol is filtered off, and 100 c.c. of the filtrate transferred to a Kjeldahl digestion flask, 3 c.c. of sulphuric acid added, and the contents evaporated on a water bath, and then the nitrogen determined in the usual w^ay. While recognising the accuracy of this method, Snyder recommends polarimetric determinations as being preferable in point of speed and of sufficient accuracy for technical purposes. The combined alcohol-soluble carbohydrates and non-gliadin proteins affect prolarisation to so slight an extent as to be negligible for practical purposes. The following is his proposed method. Weigh 15*97 grams of flour into a flask and add 100 c.c. of 70 per cent, alcohol. Shake moderately at intervals of a half-hour for two or three hours. Leave the alcohol in contact with the flour for from twelve to eighteen hours, at a temperature of about 20° C. Filter, and determine the opticity of the solution in a 220 m.m. tube. Read off on the sugar scale, and multiply by 0*2, w’liich gives approximately the per cent, of gliadin. The following are comparative results obtained by the two methods : — THE STRENGTH OF FLOUR. 307 Flours. Giiadin Nitrogen. By Kjeldahl. By Polarimeter. Spring Wheat Flour M2 MO Winter ,, ,, 1-02 1-04 1 ,, Wlieat, Patent Flour 1 1-28 1-31 {Jour. Amer. Chem. Soc., 1904, 263). 448. Commercial Wheat Testing, Snyder. — In 1905, Snyder communi- cated a paper on this subject to the American Chemical Society in which he first points out that the percentage of proteins in a flour is not necessarily a measure of its value for bread-making purposes. The following are some examples taken from the work of the Minnesota Agricultural Experiment Station : — Grade of Flour. Protein per cent. Commercial Bank of Loaf. First Patent 13-19 1 1 14-47 2 Second ,, 14-15 5 » ” 15-32 9 The following determinations are recommended as having given the best satisfaction in flour-testing : Moisture, ash, total nitrogen, giiadin nitrogen, granulation, absorptive capacity, and colour. Moisture . — Especially helpful, as an excessive moisture content, above 13, has a tendency to induce fermentative changes. Ash . — The determination is exceedingly useful in establishing the com- mercial grade of flour. First and second grades of patent flour invariably contain less than 0*48 per cent, of ash ; in case a flour contains 0*5 per cent, of ash it would not be entitled to rank with the patent grades. Straight grade flour rarely contains more than 0*55 percent, of ash, while the first and second clear grades contain higher amounts, 0*8 and 1*75 per cent, respectively. Nitrogen content . — The best bread-making flours have a total nitrogen content of from 1*8 to 2*1 per cent. A lower figure than 1*5 per cent, indi- cates deficiency in gluten, and poorer bread. Flours containing an excess over 2*1 do not as a rule have improved bread-making values, as a very high gluten is not beneficial for bread-making purposes. Giiadin Nitrogen . — The principal proteins of flour being giiadin and glutenin, it has been believed that their ratio determines largely the value of the glutinous material for bread-making purposes. Snyder finds, how- ever, that “ during some years as high as 70 per cent, of the total nitrogenous material of wheat jis soluble in 70 per cent, alcohol, while in other years flour from wheat grown under similar conditions contains as low as 45 per cent, of its proteins soluble in 70 per cent, alcohol, and that these differences have been associated with only minor variations in the size of the loaf or general bread-making value of the flour.’' Snyder believes that the percentage of giiadin in a flour is of more im- portance than the gliadin-glutenin ratio. In flours from the sam.e wheat, 308 THE TECHNOLOGY OF BREAD-MAKING. the lower’grades contain more total protein, but proportionately less gliadin than the higher ones. He also finds that any slight increase of acidity of the grain materially influences the gliadin percentage, which factjs shown in the following table ; — Constituents, etc. First Patent. Flour. Second Patent. 1 Clear Grade. Ash . . per cent. 0-39 0-47 0.84 Protein • • 9 ? 13-56 14-70 7-27 Gliadin, of total Protein . . • • 99 59-07 56-25 54-21 Acidity • • 99 0-07 0-08 0-12 Commercial rank of loaf I II 1 III Snyder does not find gliadin to be of uniform com^position, there being as great a difference as one or more per cent, in the nitrogen content of ghadin from different wiieats milled under similar conditions. This sug- gests that gliadin is lacking in definite chemical composition, possibly as a result of wheat containing m^ore than one protein soluble in 70 per cent, alcohol. He concludes that wheat gliadin is not as constant in chemical composition or physical properties as would be expected of a definite chemi- cal compound. Granulation . — This should be of mmdium fineness as such insures m-ore complete digestion and absorption of the nutrients of flour by the body. Colour . — This is one of the m.ain factors in determining flour value, as each type of wheat has a tendency to produce flour of a distinct shade. Bread-making Tests . — As yet chemical tests are not capable of accurately determining the bread-making value of a flour. They often indicate, how- ever, why a flour is deficient in desirable bread-making characteristics, and from the chemical tests ways are suggested for improving the flour, but the actual bread-making value can be determined only by comparative bread- n:aking tests. These give accurate data, including absorptive capacity and consequent yield {Jour. Amer. Chem. Soc., 1905, 1068). With an excess of nitrogen the gluten-bound condition before referred to comes into operation. The abstract of this paper is purposely introduced here because of the strong expression of opinion as to effect of the ratio of gliadin to glutenin on the quality of a flour. Snyder’s authoritative state- mient as to variations in the composition of ghadin also deserves careful attention. It] should be compared with those following of Osborne and Wood, paragraphs 449 and 453. Snyder ultimately falls back on the baking test as most accurately determining the bread-making value of a flour. 449. Gliadin, Osborne and Harris. — In reply to Kutscher’s statement that the protein matter of wheat, soluble in 70 per cent, alcohol, consists of two separate proteins, the authors have fractionally precipitated the protein matter and find all the fractions yield practically the same amount of glutamic acid. They therefore come to the conclusion that taking into consideration the composition and the physical and chemical properties of the protein, that only one such substance is present in gluten, and this, substance, gliadin, does not consist of two separate proteins {Z. Anal. Chem. 1905, 44, 516). This is not a specific reply to Snyder’s statement as to variations in the composition of gliadin from various sources. THE STRENGTH OF FLOUR. 309 450. Crude Gluten, Norton. — Norton has made a very full analysis of crude gluten as obtained from durum flour. The gluten was washed out, partly dried, flnely ground and again dried until it ceased to lose weight at 100° C. On analysis it then gave the following results : — Fats or ether extract . . Carbohydrates other than flbre Fibre Mineral Matter . . Gliadin Glutenin . . Globulin, 10 per cent. NaCl extract 4.20 per cent. 9-44 2-02 2*48 39-09 35-07 ’ 6-75 99-05 The gliadin was first removed from the gluten by alcohol, the residue was then extracted with 10 per cent, sodium chloride solution for globulin, and the residue Anally extracted with 0-2 per cent, potassium hydroxide. Nitrogen was determined in each extract and multiplied by 5-7 for protein. From the above analysis, crude gluten may be regarded as consisting of about 75 per cent, of true gluten (gliadin and glutenin) together with other matters as indicated, and which include approximately 7 per cent, of non- gluten protein matter. In summarising his results, Norton points out that the crude gluten of flours is very close in amount to that of total protein (N X 5-7), the varia- tion being in a number of samples from an excess of crude gluten of 2-31, to a deficit of 1 *30. As a rule the crude gluten is the higher for straight and low grade flours, nearly the same for patents, and less for wLole wheat meal. It follows that crude gluten is a body in which there has been a loss of non gluten proteins, more or less balanced by the retention of non-protein matters. Crude gluten is a very rough expression of the gluten content of a flour or wheat, and the determination has but little worth in the valuation of flours. The determination of total nitrogen and gliadin-nitrogen with expression of the ratio of ghadin to total protein (N X 5-7) seems to be the best simple method at hand for estimating the gluten content and ascer- taining the character of the gluten in the valuation of wheats or flours (Jour. Amer. Chem. Soc., 1906, 8). Any review of opinions as to the value of gluten determinations is best postponed until a later stage. Meantime, the results of a very complete analysis of crude gluten is here placed on record. The most noticeable feature is the retention of 6-75 per cent, of globulin, a non-gluten protein. The comparative purity of crude gluten must depend somewhat on the thoroughness of the washing treatment ; it will be observed that in the 1895 edition of this work about 80 per cent, of crude gluten is assumed to be true gluten. This was determined by a direct nitrogen estimation and substantially agrees with the sum of gliadin, glutenin, and globulin found by Norton. 451. Polarimetric Estimation of Gliadin, Matthewson. — In view of the fact that it has been proposed to estimate ghadin both by polarimetric readings and also by density determinations of its alcoholic solution, Matthew- «on has investigated the extent to which the degree of accuracy of these methods is affected by the variations which may occur in practice. He arrives at the following conclusions ; The specific rotation of ghadin in 70 to 75 per cent, alcohol is practically independent of the ghadin concen- tration. With 70 to 80 per cent, alcohol it decreases with increase in the alcohol concentration. Increase in temperature between the limits 20-45° C. produces a shght increase in the specific rotation. The change in 310 THE TECHNOLOGY OF BREAD -MAKING. density in gliadin solutions for such differences as would be met with in flour analysis would allow rather a narrow margin for experimental error. Thus solutions of gliadin in 70 per cent, alcohol had the following densities : — Grams of Gliadin per cent. Density. 0-000000 0-8686 0-004795 ■ 0-8702 0-05390 0-8865 Matthewson therefore concludes that if density of the solution be rehed on, there are disturbing causes which could easily vitiate the results (Jour, Amer. Chem. Soc., 1906, 624). Matthewson confirms the accuracy of the polarimetric method of gliadin estimation, but condemns that based on the density of its solutions. The following is an abstract of an important paper on wheat proteins. 452. Properties of Wheat Proteins, Chamberlain. — Chamberlain has invertigated various methods of making gliadin and other protein determinations in wheat and flour, and gives the following results : — Action of hot alcohol. — Experiments on the direct extraction of flour were made with 70 per cent, alcohol in order to see if hot alcohol would dissolve out more protein than cold, with the following results : — Cold Alcohol on Air-dry Flour Hot Cold „ ,, Dry Flour Protein Protein per cent. per cent, of of Flour. Total Proteins. 7*47 . . 56-80 7*32 . . 54-43 4-58 . . 34-82 The use of hot alcohol, and also the practice of drying the flour before extraction, both result in lessening the amount extracted — an effect pro- bably due to the coagulating effect of heat. Effect of different proportions of flour and extracting liquid . — Tw^o series of extractions were made. In the first, 1,000 grams of flour were extracted with 4,000 c.c. of 70 per cent, alcohol, followed by subsequent extractions using 2,000 c.c. of alcohol each time, until a total amount of 10,000 c.c. had been used. (Total equals 10 c.c. of alcohol to 1 gram of flour). In the next place 2 to 4 grams of flour were extracted, once with 100 c.c. of alcohol (25 to 50 c.c. of alcohol to 1 gram of flour). With the larger quantity of flour, the alcohol extracted 43-56 per cent, of the total proteins, and with the smaller proportion of flour, 47*15 per cent. In some further experiments flour was extracted by 70 per cent, alcohol and 10 per cent, salt solution in the ways and wdth the results given in the following table : — Modes of Extraction. Protein per cent, of Flour. Protein per cent, of Total Proteins. Direct extraction w ith Alcohol Extraction with Salt Solution after pre- ceding Extraction with Alcohol Direct Extraction with Salt Solution Extraction with Alcohol after preceding Extraction with Salt Solution . . . . j 1 1 7*47) 8-04 0-57j 2-18) 7*68 5-50 J 56-80) [61-13 4-33 j 16-57) [55-83 39-26 j When flour is acted on direct with salt solution, the albumin, globulin, and proteose are extracted. The salt remaining in the flour affects the THE STRENGTH OF FLOUR. 311 solubility of the other proteins, and consequently there is not such a high degree of extraction by alcohol as where that reagent is employed direct. But when alcohol is first employed and the flour is carefully freed from it before the subsequent extraction with salt solution, it would be expected that the yield to the salt solution would be the same as with a direct extrac- tion. Such, however, is not the case, for whereas salt solution direct ex- tracted 16*57 per cent, of the proteins, it only extracted 4*33 per cent, when used after alcohol. ‘‘This can mean only one thing, viz. that alcohol dis- solves, with the gliadin, a large part of the albumin, globulin, and proteose, which are soluble in salt solutions.'' It is probable that of these it dissolves the albumin and proteose and leaves the globulin. Chamberlain arrives at tlie following conclusions : — 1. For the proper extraction of the proteins of wheat by means of of alcohol, cold 70 per cent, alcohol should be used directly upon the air-dry wheat or flour. Relatively large amounts of solvent, in proportion to the flour, should be taken, viz. 2 to 4 grams flour per 100 c.c. alcohol, and the extraction continued for twenty-four hours with frequent or continuous shaking. Either hot alcohol or dry flour gives abnormal results. 2. The same conditions of extraction should be observed in using the salt solution, 4 to 6 grams being taken to the 100 c.c. of solvent. Five per cent, potassium sulphate solution extracts practically the same as 10 per cent, sodium chloride and is better in practice, because it avoids the evolu- tion of hydrochloric acid gas when digested in the Kjeldahl operation. 3. Alcohol extracts together vdth gliadin a large part of the salt-soluble proteins. Chamberlain agrees vdth the conclusions arrived at by Norton, para- graph 450, and confirms them by an examination of the protein material lost in the washing out of gluten, and contained in the wash-water there- from. From the results of this investigation, he comes to the following conclusions : — 1. Dry gluten is about 75 per cent, proteins and 25 per cent, non-pro- teins. 2. Of the total proteins present in wheat about 60 to 65 per cent, are present in the gluten, and about 35 to 40 per cent, are lost in the washings. 3. The balance between non-proteins present in gluten and the loss of proteins in washing, makes gluten estimations agree roughly with total proteins calculated from total nitrogen, but they wall usually fall below with whole wheat and above with flours. 4. The amount of total proteins present in gluten is about 15 per cent, less than the sum of the gliadin and glutenin determined by extraction of the wheat, and the loss of proteins in washing out gluten is more than equal to the salt solution-soluble proteins. Therefore the loss of proteins, in the determination of gluten, is at the expense of gliadin or glutenin, the true gluten proteins of wheat. 5. On account of these losses and errors it would seem that the deter- mination of gluten is not able to yield any information that cannot be gained either from the determination of total proteins or that of the alcohol-soluble and insoluble proteins {Jour. Amer. Chem. Soc., 1906, 1657). Chamberlain's conclusions are principally of value as throwing light on methods of analysis. They go also to show that the alcohol extract of flour is not pure gliadin. 453. The Chemistry of Strength of Wheat Flour, Wood. — There comes next in chronological order the account of Wood's researches. This subject has been dealt with in papers pubhshed by Wood in the Journal of Agri- cultural Science, of which the following are abstracts. The authors are 312 THE TECHNOLOGY OF BHEAH-MAKING. indebted to the courtesy of Professor Wood for copies of these and other valuable papers. The earlier paper commences vdth a discussion of the definition of Strength, and finally the writer adopts that given by one of the authors as above quoted, and also chosen by Humphries and Biffen in their paper quoted supra. Reference is made to the connection between strength and gluten, and especially to the effect caused by the presence of a proper proportion of ghadin to glutenin. It is held as proven that neither the absolute percentage of gliadin in the flour, nor the ratio of gliadin to total protein gives satisfactory indications of strength. It was therefore thought possible that gliadin might be a mixture of different proteins, or at any rate the ghadin of strong flours might differ from that of weak flours. Accord- ingly Wood made a series of determinations on the gliadins of strong and weak flour by Osborne and Harris" method of hydrolysis by hydrochloric acid, and proved the ghadin of both to be the same in chemical composition. Among others examined three flours gave results as under : — Source of Gluten. Bakers’ Percentage in Flour. Percentage Gliadin Percentage of Nitrogen Reference Letter of Flour. Marks of Flour. Total Nitrogen. Gliadin Nitrogen. Nitrogen of total Nitrogen. found in Gluten Samples. D 95 1-69 1-01 60 130 E 80 2-44 1-23 50 121 C 40 1 1-86 101 54 12-2 Examination of this table shows that neither the percentage of total nitrogen, nor of ghadin, nor the ratio of ghadin in glutenin, can be taken as a measure of the strength of flour. Thus T> and E, which are at the extreme ends of the scale of strength, are strikingly similar in nitrogen and protein composition. Attention was next directed to the water-soluble constituents of different flours. Acidities were first determined and found to have no relation to strength. Estimations were then made of total soluble matter, soluble ash, potash, and phosphoric acid. The results of such tests are set out in the following table : — Reference Letter of Flour. 1 Bakers’ Marks. Total per cent. Nitrogen in Flour. ^ Percentages of Soluble Constituents in Flour. Total Solids. Ash. Nitrogen. Alkali as K2O. Phosphoric Acid, P2O5. j Nitrogen and Ash- 1 free Extract. K 95 1-88 7-18 0-194 0-506 0-067 0-048 4-11 G (75) 2*32 4-67 0-261 0-378 0-113 0-079 2-26 I 70 L62 616 0-360 0-370 0-137 0-091 i 3-70 J 66 1-32 5-82 0-241 0-308 0-109 0-075 j 3-82 1 C . 40 1-88 4-23 0-243 0-353 0-087 0-074 i 1 1-98 The ratios of soluble ash, alkali, phosphoric acid, and nitrogen and ash- free extract, to nitrogen are set out as follows : — THE STRENGTH OF FLOUR. 313 Kefer<"nce Letter of Flour. 1 1 1 Bakers’ Marks. | 1 Ratios to Nitrogen of Soluble Ash. Alkali as K 2 O. Phosphoric 1 Aci.1, P 2 O 5 . ! Nitrogen and Ash- free Extract. K 95 9-7 1 39 39 0-45 G (75) 8-8 * 28 29 102 I 70 j 4-5 16 18 j 0-44 J 66 5-5 16 18 j 0-34 C i 1 40 7-7 29 I 25 0*91 In these ratios, the figure, 9*7 for example, means that there is 9*7 times as much nitrogen present in the flour as there is of ash. Examination of these data shows that the higher the nitrogen or proteins in the flour is in proportion to the soluble ash, the greater is the strength of flour. But to this C is an exception, since the ratio is very high, though the strength is low. If instead, the nitrogen and ash-free extract, which may be re- garded as carbohydrate matter, sugars and dextrin, be taken both G and C are exceptions. [For convenience the soluble carbohydrates may be termed “ sugars,” since these are doubtless the effective constituents. The authors.] In these flours the nitrogen and “ sugars ” are practically equal, while in the others there are between two and three times as much sugars as nitrogen. Wood remarks that “ the stronger flours contain more total nitrogen in proportion to their soluble salt content than the w^eaker ones, but to this regularity G and C are exceptions.” [It is difficult to see how the position of G agrees with this statement, since it seems to fall fairly regularly into line. G is in fact marked by a high percentage of nitrogen (and protein) coupled with a low percentage of “ sugars,” and C also pos- sesses the same characteristics ; and one is a strong and the other a weak flour.] Dealing with this flour G, Wood remarks of its baking properties that it will not make large loaves when baked by itself, but when blended with certain other flours it behaves as if it possessed great strength. This he regards as an indication of two distinct factors, one probably governing the shape of the loaf, the other its volume. The first would be the ratio of soluble salts to total protein, or at any rate some factor which modifies the physical properties of the protein. This is governed by the amount of nitrogen and ash-free extract, “sugars,” present in the flour. K contains high protein and high “ sugars,” the former being subjected to suitable conditions. I and J are weaker as they contain less protein, and a higher proportion of ash, while the sugars are also lower. In G the conditions of good shape are fulfilled, since the protein is high, and its condition of environment probably good, but it cannot make large loaves because of the low percentage of “ sugars ” present. C has high protein, but low “ sugars ” ; and an ash figure which lies betw^een those of K and G. Having separated strength into at least two independent factors, those of shape and volume. Wood further investigated the volume factor. For this purpose G was compared with L, a flour from the same kind of wheat grovm in the following year. The nitrogen of the two flours closely approxi- mated, so also did the ratio of soluble ash to proteins, but L contains more than twice as much “sugars.” The latter flour yielded large loaves of good shape. Wood next proceeds to explain that some form or forms of sugar are the active ingredient of his nitrogen and ash-free extract, and proceeded 314: THE TECHNOLOGY OF BREAD-MAKING. to make an indirect determination of the amount in a number of flours by fermentation tests. He took 20 grams each of flour and water, and 0-5 gram of yeast and fermented at 35° C. in an apparatus similar to that described in paragraph 364 of this book. The fermentation was allowed to proceed for 24 hours and the volume of gas was then observed. The actual amount of gas evolved ranged from 131 to 345 c.c. The results are set out in the follovung table : — Eeference i Letter of ' Flour. 1 Bakers’ Marks. Volume of CO 2 evolved (S = 100). Percentage total Sugar in Flour calculated as Glucose. Increase in Sugar after incubating three hours with Water at 40° C. Volume of | Loaf made 1 from 100 grams ^ Flour fS = ioo). : s 85 ICO 2-3 2-7 ICO p 90 1 94 2-6 0-6 85 0 96 ! 90 ■ — * — 80 i 1 L 85 88 2-5 — 88 1 T (20) 83 1-8 0-4 81 ' M 73 79 2-0 0-6 78 - ■ ! N (96) 77 2-2 0-4 — Q 68 66 2-5 0-5 — G2 (85) 64 — ' — 76 G3 (85) 62 1 — — 76 R 65 60 ! 1-9 0-3 70 i J 63 59 — ■ — 60 1 C 40 48 ; — — V 45 45 1 1-7 01 — j U2 60 45 — — 67 G (75) 44 I 1-6 1 — — ! U 36 37 1-6 1 04 The figures in this table are self-explanatory, except that it may be pointed out that the highest volunie of carbon dioxide evolved has been taken as 100, and the others calculated in proportion. The same thing has been done with the volum^e of the loaf. The fifth column giving increase of sugar is apparently the result of independent experiments. Generally speaking, there is a general relation between the strength of the flour as shown by bakers' marks, and the volume of carbon dioxide evolved during fermentation. But to this general rule, flours T, N, and G are exceptions. An investigation of these showed that G was deficient in sugar, and that Avhen sugar was added it was found to give a large loaf. N had had malt extract added to it when baked, and thus also its deficiency in sugar had been made up. T had been kept some time after baking, and in the interval had probably developed sugar or sugar- producing bodies. A subsequent baking showed a marked improvement in strength. From these experiments Wood reasons that they “ seem to justify the conclusion that the capacity of a flour for giving off gas when incubated with yeast and water is the factor which in the first instance determines the size of the loaf." Particular attention should however be paid to the rate of gas evolution in the later stages of fermentation, as this is shown to be more directly connected with the size of the loaf. {Wood, Journ. Agric. Science, 1907, 2, 139). The suggestion in this paper that strength runs parallel with percentage of sugar is somewhat contrary to the hitherto generally accepted views. Thus the descriptions “ a weak sweet flour," and “ a strong, harsh, dry THE STRENGTH OF FLOUR. 315 flour are very familiar. A reference to the 1895 edition of the present work shows (page 291) that No. 2 Calcutta yields 8*34 per cent, of soluble extract, and (page 339) that the loaf is small and runny, devoid of texture, and foxy. On the other hand reference (page 292) shows that a sample of No. 1 American Hard Fyfe Wheat, yielded 4*35 per cent, of soluble extract, while the corresponding Spring American patent flour (page 338) yielded a loaf which was very bold and of good texture, but with a ten- dency to become somewhat rapidly harsh and dry, and comparatively flavour- less. (The following are the corresponding references in the present edition — 291, 276 ; 339, 373 ; 292, 277 ; 338, 372. No determinations were made of sugars, but it is practically certain that they rise and fall with the total soluble extract. In paragraph 450 an account is given of some investigations of durum wheat by Norton. He there remarks that though all the durum flours have high gluten and sugar contents, yet the bread from many of the poorer durum wheat flours neither rises during the fermentation nor in the oven. 454. Effect of Sugar on Flour — An interesting side-light is thrown on the effect of the presence of sugar in flour by the following experiments. In sweet biscuit doughs it is well-known that the physical condition of the dough is materially affected by the presence of the sugar. Thus a dough made from 100 grams of flour and 50 grams of water is much stifler than one made from 100 grams of flour, 20 grams of sugar, and 50 grams of water, the latter being soft and sticky. For example, with such doughs, when tested with the viscometer, the following results were obtained. In order that the sugar dough should register equally the water had to be reduced to shghtly less than 40 grams thus : — I. Flour 100, water 50 . . II. Flour 100, sugar 20, water 50 III. Flour 100, sugar 20, water 48 IV. Flour 100, sugar 20, water 46 V. Flour 100, sugar 20, water 44 VI. Flour 100, sugar 20, water 42 VII. Flour 100, sugar 20, water 40 VIII. Flour 100, sugar 20, water 38 for the half descent of the viscometer piston. Viscometer Time. 106 seconds. 9 16 „ 28 „ 50 „ 64 „ 86 „ 364 In view of these facts, tests were made on behalf of a firm of biscuit manufactureis, and communicated to them by one of the authors in 1902. Particulars of the flours are given. The sugar was supplied by the firm in question and gave the following results on analysis : — Cane Sugar from opticity . . . . . . 98*45 per cent. Reducing Sugar as Glucose . . . . . . 0*80 ,, ,, Water . . . . . . . . . . . . 0*10 ,, ,, Mineral matter . . . . . . . . . . 0*04 I. Doughs were made with flour A and B. The wet and dry gluten were determined by washing and drying ; the true gluten by a Kjeldahl estimation on dry gluten ; gliadin by dissolving the wet gluten with 70 per cent, alcohol, filtering and Kjeldahl estimation on the filtrate ; glutenin by subtracting gliadin from the true gluten. II. Doughs were made from 100 parts of flour and 20 parts of sugar (sugar-dough). The gluten was washed out with water, and weighed wet and dry. True gluten was determined as before. Gliadin was deter- mined by dissolving wet gluten with 70 per cent, alcohol, containing to 100 parts of alcohol, 20 parts of sugar (sugar-spirit), filtering, and a Kjeldahl 316 THE TECHNOLOGY OF BREAD-MAKING. estimation in the filtrate; glutenin, by subtracting gliadin from true gluten. Constituents. A. B. Ordinary, Sugar-dough. i Ordinary. Sugar-dough. 1 i Gluten, wet . . . . 37*2 35-9 26-7 23-9 ! „ dry 11-3 11-7 8-2 7-7 ,, true 10-4 100 7-5 7-2 Gliadin ex Gluten . . ' 3-6 7-2 30 5-6 Glutenin . . 6-8 2-8 4-5 1-6 In all cases the sugar caused a diminution of the quantity of gluten recovered, except in the case of the dry gluten of flour A. When extracted with, alcohol, much more of the gluten was dissolved by the sugar-spirit, than the ordinary alcohol, showing that sugar has a marked solvent action on wet gluten. (As all these gliadin determinations were made in the pre- sence of excess of carefully washed precipitated chalk, CaCOg, there could have been no free acid present.) In the next place, the total protein of the flours w^as directly estimated by Kjeldahl’s method. The proteins soluble in water were determined by directly treating the flour, filtering and Kjeldahl’s process on the filtrate. The proteins extracted by a 20 per cent, aqueous sugar solution were simi- larly determined. The proteins soluble in 70 per cent, alcohol were estimated by direct treatment of the flours, and a Kjeldahl estimation on the filtrate. The proteins similarly dissolved by 20 per cent, of sugar in 70 per cent, alcohol (sugar-spirit) were also determined. The following are the results in percentages obtained on the same two flours : — Constituents. A. B. Total Proteins 11-6 11-6 9-9 9-9 Proteins soluble in Water ,, ,, Sugar- water 10 1-5 0-5 ; i 2-5 Gliadin and Glutenin 10-6 101 9-4 7-4 Soluble in Alcohol, Gliadin ,, ,, “ Sugar-spirit ” 6-4 7-5 4-6 5-7 Insoluble, Glutenin 4-2 2-6 4-8 1-7 It is assumed here that water and sugar-water respectively do not dissolve the same proteins as are dissolved by alcohol and sugar-spirit ; probably however there is some overlapping. As the experiments are com- parative this does not affect the point under consideration. It will be noticed that in eveiy case there is an increased solvent power exerted when sugar is present. These tests were confirmed by others on four other samples of flour. In all cases, sugar-spirit dissolved considerably more protein than did plain alcohol. Sugar diminishes rather than increases the water absorptive power of the flour. In small quantities it is very THE STRENGTH OF FLOUR. 317 possible that its solvent action on the gluten may effect sufficient softening to increase the gas-retaining power of the dough and thus indirectly increase the strength of the flour. 455. The Shape of the Loaf, Wood. — ^Following up his previous paper, Wood made a subsequent communication on what he regards as the second factor of strength, viz. that which decides the shape of the loaf, and this was tentatively ascribed to the soluble salts present in the flour. A further investigation was made of this hypothesis, and first acidity and soluble salts were determined in a number of wddely differing flours. But bakers' marks were found to exhibit no relationship to either acidity or soluble ash, though there appeared to be some relation between bakers' marks and the ratio of soluble ash to total nitrogen. Further investigation confirmed this relationship, and led to a study of the effects produced on wet gluten by its immersion in various solutions. Apparatus used . — A quantity of gluten was prepared from ordinary flour. A large number of small beakers was each marked at 80 c.c. Nor- mal hydrochloric acid was then run into each in such quantity as to pro- duce the desired strength when water had been added to the 80 c.c. mark. Pieces of V-shaped glass rod were prepared which would rest on the edge of the beaker and with the lower point in the solution. A piece of gluten was taken for each experiment about two inches long and as thick as a pencil : this was hung by its middle point on the V-shaped glass support, the gluten being thus immiersed in the solution. With mineral acids, no antiseptic was necessary, but in all other cases the solutions were made up with water which had been shaken with toluene. With distilled water, the gluten retained its coherence until changed by bacterial action, or with frequent changes of the w^ater until all acids and salts had disappeared. Effect of Acids . — Very dilute hydrochloric acid, N / 1000 caused rapid disin- tegration and loss of coherence in the submerged gluten. This change w^as accelerated by an increase of the strength of the acid up to N/20. Further concentration slow^ed down the rate of charge until at A /1 2 the gluten became permanently coherent and much harder and more elastic, and less sticky than in its original condition. [Compare this with the effects of w^eak and somewhat stronger acids on the diastatic capacity of flour, par. 137, 1895.] Experim^ents with sulphuric, phosphoric, and oxahc acids, show^ed them to behave similarly to hydrochloric acid, but with different limits of con- centration for permanent coherence. Working upwards from a very dilute solution, the following are such limits ; — Hydrochloric Acid . . . . . . . . . . A/12 Sulphuric ,, . . . . . . . . . . A/25 Phosphoric ,, .. .. .. .. .. 1*75 N Oxalic . . , , . . . . . . . . . . A/4 Experiments with acetic, lactic, citric, and tartaric acids, show'ed these to behave differently. Dilute solutions caused disintegration, and this becam.e more rapid with greater concentration. At no point did coherence reappear. Mixtures of Acids and Salts . — An extensive series of experim^ents w^as next made with gluten and mixtures of acids and salts. The proportion of each was varied, and the results noted. In the first place hydrochloric acid and sodium chloride (common salt) were employed. Using A/50 acid (which was a disintegrating strength) it was found that salt was required up to a degree of concentration of N/12 in order to secure coherence of the immersed gluten. With either more or less acid, less salt was required. The action generally of the salt was a binding one, and in certain quantity it overcame the disintegrating effect of the acid. In conj unction with acids. 318 THE TECHNOLOGY OF BREAD-MAKING. three sodium salts were made the subject of experiment, the chloride, sulphate, and phosphate. The chloride and phosphate were about equal in power of producing coherence, the sulphate being much more active than either of the others. On making similar tests with the sulphates of sodium, magnesium, and aluminium, their activity 'increased in the order given, the ratios being roughly expressed by 1:2:4. As lactic acid disintegrates gluten at all strengths it shows a different behaviour with salts. As the concentration of the acid is increased, so must also that of the salt in order to preserve coherence. The amount of soluble salt required to produce a certain degree of co- herence with such an acid as hydrochloric acid at first increases with the acidity up to a maximum and then falls off again. During the period in which the acid is acting as a disintegration agent, the more that action increases, the greater the amount of the binding salt is necessary in order to counteract that effect. But as the acid action diminishes with a further increase in concentration, less of the binding salt becomes necessary. The connection between the two is therefore not so obvious as it otherwise might be. [In passing it may be stated that no mention is made of experi- ments with neutral salts only in the absence of acids.] On immersion of pieces of gluten for forty-eight hours in mixtures of acid and salt in which the proportions are such as just to maintain coherence, they are found to be far inferior in coherence, toughness, and elasticity to samples of fresh gluten from the same flours. On weighing such gluten both in the wet and dry state, the ratios were found to be approximately 5:1. With an increase in the degree of concentration of the salt, the gluten gets drier, and the ratio more nearly approaching that of freshly washed gluten. This property seems to offer an explanation of the well-knovTi difference in water-absorbing capacity found in certain flours, and since the tough- ness of the gluten increases as the water content falls, to connect both water absorption and toughness of gluten with acidity and content of soluble salt. Conclusions . — Wood sums up his conclusions as follows : — “ The experi- ments above described suggest that the variations in coherence, elasticity, and water content, observed in gluten extracted from different flours, are due rather to varying concentrations of acid and soluble salts in the natural surroundings of the gluten than to any intrinsic difference in the composition of the glutens themselves. These properties must undoubtedly have a direct bearing on the power which some flours possess of making shapely loaves. I suggest therefore that the factor of strength on which the shape of the loaf depends is the relation between the concentrations of acid and soluble salts in the flour.'' Confirmatory Tests . — One possible method suggested is that of determin- ing acidity and soluble salt content of a flour, and then modifying them by the addition of acid, alkali, or salt. This would be followed by baking tests in order to discover if the treatment had altered the water-absorbing capacity or the shape of the loaf. But the author of the paper foresees an objection, inasmuch as the small piece of gluten taken for a test requires forty-eight hours in order to become permeated with the solution in which it has been immersed. Obviously, dough cannot be allowed to stand forty-eight hours before baking. An alternative method suggested is that determining the acidity and soluble salt content of a number of flours and comparing them with the baking properties. But these figures will require to be considered in relation to the nature of the acids and salts, and their degree of concentration The degree of concentration of the acid and salts must be changing during the whole period of formation of the grain, and the question arises as to Avhat stage of growth it is at which they imprint upon THE STRENGTH OF FLOUR. 319 the gluten those physical properties which decide the character of the flour. Wood regards this time as being that when the endosperm is being formed and is in a comparatively milky stage. The author of the paper realises th? t his “ results are at present only in what may be called a suggestive state.’' {Wood, Jour. Agric. Science, 1907, 2, 267.) 456. Solubility of Gluten on Ionisation Hypothesis, Wood and Hardy. — These chemists have contributed a paper to the Royal Society in which they deal with the solution of gluten in weak acids on the hypothesis of ionisation. They point out that the colloidal solutions of characteristically insoluble bodies are distinguished by the fact that round each particle of the solute (substance dissolved) there is an electric double layer, and on the potential difference between wiiich the stability of the solution de- pends. “ On this view the formation of the hydrosol (aqueous solution) of gluten is due to the development of electric charges round the particles of the protein owing to chemical interaction between the protein, the acid or alkali, and the water : and the tenacity, ductility, and w^ater content of a solid mass of moist gluten depends upon the total or partial disap- pearance of these electric double layers, and the reappearance of wLat is otherwise obscured by them, namely, the adhesion or ‘ idio attraction ’ as Graham called it, of the colloid particles for each other, wiiich makes them cohere when they come together.” This form of solution being due to ionisation, when the concentration of acid rises above a certain value, there is a decrease and finally a disappearance of the potential difference, due to the suppression of the feeble ionisation by the excess of acid. (Wood and Hardy, Proc. Roy. Soc. 1909, B 81, 38.) This is interesting as a step toward bringing the phenomena of the solubility of gluten into harmony with the ionisation theory. 457. An Analysis of the Factors contributing to Strength in Wheaten Flour, Hardy. — Hardy further elaborated and explained his view s on the relation of strength to electric potential in a paper read by him at the meet- ing of the British Association for the Advancement of Science, 1909. He compares dough to rubber loaded with solid particles, the gluten being the analogue of the rubber, and the starch contributing the solid particles. He goes on to say : — There has, so far as I know, been no exact work upon the influence of the size and number of the starch grains upon the mechanical properties of dough ; in the absence of such information it is idle to pursue the point further. This may, how^ever, be said : judging by what is knowm of the influence of embedded small particles in other cases, the power of the dough to retain its shape may be due in some cases primarily to the nature and number of the starch grains. But the essential active agent is the protein-complex gluten. Now gluten, even though it be prepared from the best Fife flour, has of itself neither ductility nor tenacity. In presence of ordinary distilled water it partly dissolves, the residue — the larger portion — forming a semi-fluid sediment destitute of tenacity. Why ? Because tenacity and ductility are properties impressed on gluten by something else — namely, by salts, by electrolytes, that is, which may be organic and may therefore be unrepre- sented in an ash analysis. This being the case, it is obvious that any attempt to correlate strength with the physical properties of gluten washed out in the ordinary way must end in failure, since the properties of washed gluten depend upon the elec- trolytes which happen to be left in after the w-ashing is concluded. Electrolytes — that is to say salts, acids and alkahs — intervene in tw o absolutely distinct ways. They control the physical properties of the gluten in the dough, and they must also profoundly modify the temperature rela- 320 THE TECHNOLOGY OF BREAD-MAKING. tions and the rapidity of the change undergone by the gluten and other con- stituents of the dough in the process of baking — a change which, so far as the proteins are concerned is, broadly speaking, a lowering of solubility. We know something of the way in which they act on gluten in the dough, but of the more complicated action during temperature changes we know nothing ; it is possible that the same electrolyte may increase the mechani- cal stability of the loaf in the dough and yet diminish it in the oven. The writer next summarises the results of Wood’s experiments before described, in which it is shown that certain very dilute acids disperse gluten in fine particles, which are so changed that they actually repel one another, such repulsion being overcome and cohesion restored by the neutralisation of the acid or the addition of any salt such as common table salt. The cohesion of gluten is due to the salts naturally present ; and their removal, as by washing with distilled water, causes the breaking down of the gluten. When gluten is thoroughly extracted with distilled water it loses cohesion and disperses as a cloud, not owing to the action of the water, but because of the faint acidity due to the carbonic acid dissolved from the air. In the absence of salts, this is sufficiently strong to destroy cohesion. In cases v'here the quantity of salt is insufficient to counteract that of the acid, the gluten is in a state of colloidal solution, containing exceedingly fine particles of gluten. With an increase of salt the particles become continually coarser, until finally they run together into a coherent mass of gluten. As the salts present still further increase, there is still further separation of water, and as the water-holding power of the protein diminishes, so also does its duc- tility, while at the same time there is an increase in the tenacity. Electrolytes, therefore, do more than confer on gluten its mechanical properties ; they determine also its power of holding water. They also determine the water-holding power of any other colloid matter present in the dough. Acids and alkalis destroy cohesion and disperse the particles of gluten just as they produce and stabilise non-settling suspensions in many types of colloidal solution — namely, by the development of a difference of electric potential between the particles and the water. The curve which connects the potential difference with the concentration of acid has the same form as that which represents the region of gluten non-cohesion. The foregoing analysis of the factors which control the physical pro- perties of gluten in moist dough lead us to a brief analysis of the source of “ strength ” in flour. It must be borne in mind that loaf -making includes two distinct operations, the making and incubation of the dough and the fixation of the incubated dough by heat. Every factor which contributes to the rising of the dough — that is, to the size of the loaf — and to the power of the dough to preserve its shape (saving only the vital activities of the yeast plants) intervenes also in the fixation of the dough, where it may undo what it has already done. Successful incubation depends upon : (1) The suitability of the dough for the active growth and production of car- bonic acid by the yeast plant, which again depends upon the concentration of sugar, the intrinsic diastatic power of the dough and the concentration and nature of the electrolytes. (2) The physical character of the dough, wliich depends upon the size, shape, and number of starch grains, the nature and concentration of the electrolytes, since these determine the physical properties of colloids present, notably the gluten. The electrolytes will also direct tiiose molecular rearrangements which occur during the baking process and which give fixity and stability to the entire structure. (Supple- ment, June, 4, 1910, p. 52, Jour. Board of Agric.) Snyder had previously dealt with the effect of variations in the quan- tity of starch on the character of dough, and concluded that they were THE STRENGTH OF FLOUR. 321 without any marked effect (paragraph 444). One of the authors had pre- viously showTi that with flours having different quality glutens, such glutens maintained their individual character through a long range of variations produced by the addition of starch (paragraph 438). Hardy advances the paradox that gluten, even of the strongest flour, “ has of itself neither ductility nor tenacity.'’ The correctness of this dictum depends on the deflnition of the word “ gluten." In the primary sense in which that word is almost universally employed, gluten is the name of that elastic, ductile, and tenacious mass, whatever may he its composition, which is obtained by washing dough in the recognised manner. Gluten has hitherto been sup- posed to consist essentially of protein matter, but Wood’s researches go to show that certain salts exercise a profound influence on its character. The presence of these may in fact be regarded as a necessity, and if they be removed the remaining body or bodies is no longer gluten in the generally accepted sense of the word. Putting it another way, the proteins of gluten, in the absence of electrolytes, are collectively neither ductile nor tenacious. But from this it does not folloAV that no relation exists between the strength of a flour and the physical properties of its washed-out gluten. It is gener- ally agreed that the physical strength of dough, i.e., its ductility and ten- acity, depends on the quantity and quality of the gluten it contains, using that word in its evident sense as including proteins, electrolytes, and all that goes to give that body its essential characters. As a matter of fact, the general rule is that a properly washed-out gluten correctly reflects by its quantity or quality, or both, the strength of the flour from which it was obtained. To this the exceptions are remarkably few, and interesting evidence of the value of this test was given by Saunders in the course of a paper read by him at the same meeting, and quoted at the close of this chapter. When gluten washing is done with suitable water, sufficient electrolytes remain in the gluten to conserve its characteristic properties, and enable a judgment to be based thereon. The writer’s speculations as to the effect of electrolytes through the v'hole process of baking, as well as of fermentation, are of interest, and may very probably indicate the direction in which the future solution of many problems may be found. The relationship of cohesion of gluten to electric potential is clearly indicated, but the question remains whether any part of the operations of baking falls vlthin, or even approaches, the region of non- cohesion of gluten. Taking the figures given in the writer’s paper, about 22 grains of common salt per 1,000 litres is sufficient to neutralise the maxi- mum disintegrating effect of sulphuric acid. The word grain may possibly be a misprint for gram, and if so the figure is 22 grams per 1,000 litres. As- suming this latter to be correct, then the degree of concentration is 22 grams per 1,000 litres = 22 grams per 1,000,000 grams of water. In bread-making salt is always used, and to an extent of about 3 lbs. to the sack of 280 lbs. of flour. To the water, salt is taken in the approximate proportion of 2 lbs. of salt per 100 lbs. of water, which equaU2,000 grams of salt to 1,000,000 grams of water, or about ninety times the concentration for the critical point in Hardy’s curve. The question of the influence of sugar upon strength has been already discussed, and vitli it much of the importance or otherwise of the diastase of dough is closely connected. Snyder’s work already referred to goes to minimise the effect of starch grains. 458. Size of Starch Grains, Armstrong. — The size of wheat starch grains was also referred to by Armstrong in a paper read at the same meeting. He states that microscopic examination shows flour to consist of starch granules of three different sizes. The smallest granules which preponderate in amount are from 3 to 5 /x in diameter, the largest granules are about 30 to 35 /X, and there are also granules of intermediate size. The microscopic Y 322 THE TECHNOLOGY OF BREAD-MAKING. examination of a large number of flours of different origin has shown that the large granules vary in number from 6 to 1 J per cent, of the total number of granules. In other words, in one flour as much as 30 to 40 per cent, of the total weight of starch is in the form of large grains, whilst in another only 7 to 10 per cent, is in this condition. Before a starch grain can be converted into sugar the cellular envelope has first to be destroyed. Obviously, when the envelope of the large granule is destroyed a much larger proportion of starch is rendered available than when the contents of a small granule are liberated. Whymper has recently made a microscopic study of the changes occur- ring during the germination of wheat. He finds that the larger and more mature granules are the most readily attacked by the enzymes of the planta- let. Though there is no general relation between the size of starch granules of different origin and the ease with which they are attacked by diastase and other agents, it appears that the larger granules of any particular starch are affected sooner than the smaller granules. {Supplement, June 4, 1910, p. 49, Jour. Board of Agric.) Armstrong’s examination of starch is evidently the result of his con- clusions that flour does not contain sufficient sugar for bread-fermentation, and that the requisite sugar is always provided by the hydrolysis of starch. With the object of further investigating the effect of different sizes of starch granules, the authors made the following experiments. A strong American flour was taken, being No. 6 in the Table of Flours and Wheats, described in Chapter XXVIII,. To 80 parts of this flour there were added and thoroughly mixed 20 parts of potato, wheat, and maize starches respectively. The potato starch granules are considerably larger than those of wheat, while those of maize starch are very much smaller. [Compare with dimensions given in Plate I and accompanying description in letterpress.] In these three mixed flours the average size of the starch granules was therefore increased in the first, unaltered in the second, and diminished in the third. The original flour yielded 15-02 per cent, of dry gluten, which gives the mixed flours an amount of 12-01 per cent, m each case. Viscometer determinations of water absorption gave the folloving results in quarts per sack ; — 1 Flour only. ; Flour and Potato Starch. Flour and Wheat Starch. Flour and Maize Starch. Quarts. Seconds, i Quarts. 1 Seconds, j Quarts. Seconds. Quarts. Seconds. 65 315 65 90 — — — 66 81 66 102 I 66*5 60 — — — — 67-0 60 — — 68 227 1 68 42 68 i 48 68 54 70 52 70 27 70 28 70 37 72 43 1 ~ j The figures in heavier type are those which practically agree with the sixty seconds standard. The whole of the starched flours have fallen off in water-absorbing power. Throughout the series of tests, this falling off has been greatest with the potato starch and least with that of maize. The difference may probably be accounted for by the greater surface offered by the smaller starches in proportion to their weight. Baking tests were next made with the flours with the special object of THE STRENGTH OF FLOUR. 323 observing their strength behaviour both in the dough and the loaf. A stiff dough was made from each for crusty Coburg loaves. The water taken was in the same proportions as in the viscometer tests. Those from the three mixed flours fermented much more rapidly than did the unmixed flour, which latter made a bold sweet loaf, while the former on falling in the dough was unable to rise again either during fermentation or in the oven. The starch-mixed loaves were all distinctly over-worked and sour to the nose. A second test was made in which the three mixed flours were fer- mented for a shorter time, as nearly as possible three-quarters of that required by the unmixed flour only. In this case much better results were obtained, but all the doughs fell off in the latter stages of fermentation, and had comparatively little “ spring "" in the oven. The differences in behaviour were very slight ; but if anything the potato starch loaf was least tough and “ springy "" (elastic) in the dough, and rose least in the oven. The wheat starch loaf came next, and the maize starch gave the best results of the three. 459. Water-soluble Phosphates in Wheat, Wood. — Professor Wood has kindly forwarded to the authors in 1910 an advance note of experiments recently performed by him, of which the following is a summary : — Wood made a number of analyses of the water extract of different flours. The method used was to shake up 200 grams of flour with 2,000 c.c. of water containing a few drops of toluene to delay ferm^entation. The shaking was continued for one hour, and the mixture then filtered. Ahquot portions of the clear solution were then evaporated to dryness, and their content of phosphoric acid, lime, magnesia, chloride, and sulphate determined. He finds that in all the flours made from Fife wheat, the water soluble phos- phate is high — over OT percent, of the flour, and the chlorides and sulphates very low. They also contain more magnesia than lime. Wood has ex- amined about half a dozen samples of Fife, som.e grown in Canada and some grown in various parts of England, and they all agree in these respects. Weak wheats of the Square Head’s Master type, and in fact all the wheats he has examined, except the Fifes, and one which cam^e from Japan, contain from 0*08 per cent, to as low as 0’04 per cent, of water-soluble phosphoric acid, and correspondingly higher amounts of sulphate and chloride, and as a general rule m.ore lime than magnesia. Wood has little doubt that the peculiar properties of the gluten of the Fife wheats is due to their high content of water-soluble phosphate, and believes that the determination of the water-soluble phosphate gives a gi'eat deal of information as to the character of the gluten content in a flour. {Personal Communication, May, 1910.) As Wood’s papers form a connected series, it was thought preferable not to separate them. Reverting now to somewhat earlier researches, the record is resumed by the following abstracts : — 460. Can Glutenin absorb Gliadin ? Matthev/son. — In 1908 there were published the reults of some experiments made by Matthewson in order to investigate the point as to whether or not glutenin possesses any absorj)- tive power for gliadin in an alcoholic solution. A sample of flour was freed from gliadin by cold extraction with alcohol, washing with concentrated alcohol and drying. This flour was added to a solution of pure gliadin in alcohol, shaken repeatedly for three hours, allowed to stand over night, and filtered. The filtrate had suffered no change in gliadin content by its con- tact vuth the gliadin-free flour. In a second experiment dry glutenin was used, having been prepared in the following manner : — Thoroughly washed gluten was cut into small pieces and extracted with successive portions of 324 THE TECHNOLOGY OF BREAD-MAKING. dilute alcohol, washed with strong alcohol, dried at room temperature* ground to a fine powder, extracted with ether and with absolute alcohoh again extracted repeatedly with dilute alcohol, rinsed with strong alcohol, and dried at room temperature. The glutenin w^as added to the ghadin solution, in which it sw'elled up. On filtering, the ghadin solution w^as found to have become more concentrated, showing that instead of the glutenin having removed gliadin from the solution, it had evidently absorbed either w'ater or dilute alcohol. The obvious conclusion is that glutenin ha« no tendency to remove gliadin from its alcoholic solution. {Jour. Amer.Chem. Soc., 1908, 74.) The above is a somewhat interesting investigation, and should be com- pared with the experiment of Osborne and Voorhees described on page 115, in which additional gluten is obtained by adding ghadin to flour, and then washing out the gluten in the usual manner. Compare also with the experiments on adsorption by chalk and kieselguhr, given in the descrip- tion of ghadin determinations in Chapter XXVIII. 461. Amylolytic and Proteolytic Ferments of Wheat, Ford and Guthrie. — This investigation was undertaken with the view of examining the action of diastase and like bodies on the starchy and protein m-atters of wiieat. In measuring the amylolytic powder of the ferments present in wEeaten flour, the wTiters employed soluble starch of R. 1*0 as the hydrolyte, and expressed their results in terms of grams of maltose produced by the filtered extract of I gram of the substance acting on excess of soluble starch for one hour at 40° C. Duration of Extraction . — In the following experiments 20 gram-S of flour were added to 500 c.c. of w^ater at 18° C.,and shaken up by a shaking machine for the times given in the table, after wiiich they were filtered and tested : — 1 ^ Grams of Maltose per 1 Gram of Flou’'. Time of Extraction. Minutes. ' ! Xo. 1. i No. 2. 1 1 10 1 8*88 12*88 30 ! 8*03 13*58 60 , 5*38 13*65 90 3*48 11*41 120 3*00 9*31 It is obvious from these results that destruction of the enzyme occurs with varying rapidity after the addition of the w ater to the flour. Sample No. 1 was acid in reaction, and sample No. 2 very faintly alkaline to rosolic acid, and as it seemed probable that the acidity w'as the cause of the loss of ferment activity, an attempt w^as made to adjust the “ neutrality ” of the aqueous extraction by the addition of 2 grams of potassium di-hydrogen pliosphate plus 0*2 gram of di-sodium hydrogen phosphate per 500 c.c. of water. When flour No. 1 w'as thus extracted for thirty minutes, it gave 14*28 grams of maltose as against 8*03 in the preceding table. The addition of certain neutral salts to the w^ater was also found to have a protective effect. Taking potassium chloride as an example of these, the addition of 40 grams per litre to the extraction w^ater, and then digestion of the flour for eighteen hours at 30° C., resulted in a maltose yield of 18 '90 grams as against 4*06 grams with the flour above. Toluene w^as used as an antiseptic in these experiments. THE STRENGTH OF FLOUR. 325 Protective action of Proteolysts. — It is found that flours contain large amounts of amylase [diastase] which may be extracted in an active condition by the use of a suitable proteolyst. For this purpose active papain was found the most suitable, and vdth the flour used in the experiment vdth potassium chloride (Hungarian) a figure of 27*4 grams of maltose was ob- tained from the 1 gram of the flour, while vuth a high grade Canadian flour as much as 48 grams of maltose were produced. The amylase thus obtained is for convenience called “ total amylase,'' and is determmed in the following manner : 2 grams of the flour are digested with 50 c.c. oi a 1 per cent, solu- tion of active papain for eighteen hours at 30° C., the solution is then fil- tered, and J c.c. of this is added to 70 c.c. of starch solution (containing 2 grams of starch) at 40° C., after thirty minutes the action is stopped by the addition of 5 c.c. of soda solution (10 grams per litre). These conditions give concordant results, but it is preferable to dilute 25 c.c. of the filtered solution to 100 c.c., and then to use 1 c.c. of this and allow the action to proceed for one hour. The same values are obtained by either manner of working, but departure from the general conditions is not admissible. As amylolytic action requires for its full development the presence of neutral salts, it is advisable to make an addition of same as those naturally present in wheat flour vary considerably. It is, therefore, recommended to add to the papain 0*5 grams, and to the soluble starch 0*25 grams respectively per 100 c.c. “ Autodigestion " of Flours. — An experiment was made vflth the two flours previously used. Nos. 1 and 2, in which they were digested with water alone for a stated time at 30° C. As before, 20 grams of flour were taken to 500 c.c. of water : — Time. Grams of Maltose per 1 Gram, of Flour. No. 1. No. 2. After 1 hour 2*87 11*83 ,, 3 hours 2*87 11*90 „ 4 „ 2*80 11*69 „ 5 ,, 2*66 11*34 „ 26 „ 2*52 12*74 It will be noticed that sample No. 1 falls in value, whereas No. 2 shows an increase at the end of five hours. The writers regarded this as an indi- cation that the second flour contained a proteolytic enzyme, a surmise which subsequent investigation proved to be correct. It was thought that this method might prove of service as a differential test, but as Avhatever results are obtained are the product of a number of factors, the authors discarded it as not applicable for general employment. [It is interesting to note here that digestion for one hour at 30° reduced the amylolytic power of No. 1 flour to a greater extent than two hours at 18° C. (2*87 and 3°00 respectively). On the other hand. No. 2 flour has a greater capacity of resistance to heat, since one hour at 30° gives a maltose result of 11*83 as against 9*31 for two hours at 18° C.]. Carbon Dioxide yield of Flour. — Humphries regards the capacity of flour for carbon dioxide gas formation as one important factor in its strength {Brit. Assoc. Rep., 1907). The writers point out the greater part of the carbon dioxide liberated in panary fermentation must be derived from the starch of the flour by the intervention of diastatic action, and therefore it 326 THE TECHNOLOGY OF BREAD-MAKING. seemed likely that flours wdth the greatest amount of amylase would, other things being equal, stand highest in baking value. A slight calculation shows that the pre-existent sugar in wheaten flour can only account for a small proportion of the carbon dioxide formed. Taking as an example, a N. Manitoba flour, which when fermented in the usual way with yeast yielded some 350 c.c. of gas per 20 grams : this corresponds roughly with the fermentation of 1*3 gram of sugar or 6*5 per cent, on the flour. In this flour the amylase was destroyed by first boiling the flour with 95 per cent, by volume alcohol for one hour, filtering, and air drying. (In determining the strength of the alcohol, allowance must be made for the water present in the flour. Analyst, 1904, 277). A subsequent determination of sugars gave 0*82 per cent, of sucrose and 0*1 per cent, of a reducing sugar. Mani- festly then, amylolytic action plays a prominent part in providing sugar for the fermentation. Total amylase was determined in a number of flours which had been previously subjected to baking tests by Humphries, by whom “ bakers’ strength marks ” had been awarded (maximum 100). The following table shows the comparative results : — Sample Flour. ! Strength, Bakers’ Marks. Value, Total Amylase. Arrangement by Baking. Amylase. A 68 26-8 1 c F B 70 29*2 I J C C 96 43-2 1 K J D 40 34-3 1 F E E 76 to 86 35-8 i H H F 88 46*8 I I G 68 25-4 E K H 85 32-3 : B B I 85 31-7 i G A J 92 38-8 A G K 90 29*6 D D L 35 221 L L 1 Flours D and L were found to contain an active proteolytic enzyme, which enzyme was found to have an extremely detrimental influence on the tenacity of the gluten, and hence on the property of gas-retention. The results of the examination of this series of samples show, not greatly to the surprise of the writers of the paper, that potential gas-producing power, as measured by the total amylase of the flours, quahfied by the presence or absence of an active proteolyst,is not sufficient to assess their baking value. It, however, indicates that in developing a method of valuation the total amylase is one important factor, also that the presence of a proteolytic ferment is another, and possibly more valuable, consideration. In con- nection \vith sample F the writers made a slightly extended examination. The baking test showed that this flour “ gives an extraordinary amount of gas, but the dough does not hold it.” This sample did not contain any active proteolyst, but resembled sample D in respect of its soluble nitro- genous constituents. Its salts and soluble matters were also high, and it is therefore probable that in the original grain the metabolism of the endo- sperm had not attained such full maturity as that from which sample C was milled. Detection of active Proteolyst, Protease . — This enzyme may readily be detected by a modification of the usual gelatin test. For this purpose, 5 THE STRENGTH OF FLOUR. 327 grams of the flour are added to 50 c.c. of 1*5 per cent, gelatin (pure) solution saturated with nitrobenzene, and the mixture digested at 35° C. for at least forty-eight hours. By this test samples such as “ D and “ L show obvious hquefaction. As a control, a check test should be made with a flour known to be free from a proteolyst. In order further to demonstrate the detrimental action of this active proteolyst, the authors supplied Hum- phries with a preparation of protease equal in activity to about five times that present in “ D.'" On making a baking test with this preparation against a control, within a quarter of an hour of making the dough, it was seen that something very abnormal w^as taking place. The final loaf was quite useless ; it had practically failed to “ rise ” at all, and the crumb Avas devoid of tenacity. Humphries proved to his satisfaction that it was gas retention and not gas making w hich this proteolytic enzyme had affected. The above experiments suggest a reason why certain preparations of malt extract prove unsuitable for use as baking adjuncts, and also provide one explanation for the cause of wdiat is known as “ rotten "" gluten. The WTiters suggest that the problem of how far the presence of a proteolyst in wheaten flours is due to racial, climatic, or soil influences is a fit subject for future investigation. [Jour. Soc. Chem. Ind., 1908, 389.) That there are both amylolytic and proteolytic enzymes in flour was w ell recognised at the time of WTiting this paper, the principal importance of w hich hes in the data obtained under certain conditions of exact measure- ment. Dealing first wdth the starch converting body, it is shown that the activity of the enzyme extracted diminishes wdth the length of time of extraction, though much more rapidly with one flour than wdth another. It is further found that proteolysts when present in flour assist in the main- tenance of the activity of its amylase. The extraction of amylase in the presence of papain (a proteolytic enzyme) results in obtaining a very active preparation of amylase, which the writers have provisionally termed “ total amylase.'" The action of this amylase on the flour itself is shown in the “ autodigestion " experiments described, and has an important bearing on the carbon dioxide yield of flours. To both subjects a more extended reference is subsequently made. After examining a number of samples of flour for total amylase, the wHters arrive at the conclusion that this factor is not sufficient to assess the baking value of a flour, although it is of considerable importance. Having regard to the protective influence of proteolysts, they deem the presence of these bodies as being valuable. Con- sidering the sample F, it is pointed out that although gas is generated in its dough in large quantity, yet the dough has no gas-retaining power ; and this was found to be associated wdth the absence of any active proteolyst. Evidently such absence Avas no obstacle to active amylolytic action, and if it had any effect it must have been due to the absence of proteolytic action proper and not to any protection afforded to amylase. It is interesting to note that D, a very Av^eak flour, had a high proportion of salts, a result Avhich may be compared Avith Wood's experiments on the relation of salts to strength. That certain flours contain a proteolytic enzyme is proved by the gelatin test described, but the action of this active proteolyst is regarded by the AVTiters as detrimental, and possibly one of the causes of rotten gluten. 462. Strength of Wheat Flours, Baker and Hulton. — Simultaneously Avith the foregoing research by Ford and Guthrie, Baker and Hulton inves- tigated the problem of the strength of flour. The Avriters do not regard it as possible that the estimation of one constituent or the determination of one physical property AviU enable the chemist to affix a baking value to a flour, when this value is the resultant of more than one factor. They attach considerable importance to Wood's observations bearing on the effect of 328 THE TECHNOLOGY OF BREAD-MAKING. acids and salts on the physical character of glutens. Although his results cannot be correlated Avith Bakers’ marks, they feel sure it is in this direction that further light will be thrown on that gluten-character which, in their opinion, forms one of the two or three essentials concerned in “ strength.” In view of the negative results so far obtained by many investigators, they regarded a study of the enzymic activities of flour as likely to furnish results of interest. Gluten in the grain of wheat, apart from its interest to the baker, exists primarily as a reserve of nitrogenous food material for the young embryo, and proteolytic enzymes are consequently secreted to render this reserve available on germination. They have pointed out that the appearance of white of egg when treated in presence of toluene wdth an aqueous extract of flour was considerably altered, the albumen being dis- integrated and the solution becoming milky, but that there was no increase of soluble nitrogen in aqueous flour extract after digestion for four hours at 30° C. in the presence of white of egg. Wlien flour extract was allow^ed to act on its separated gluten for eighteen hours at 37° C., there was practically no evidence of solutiona nd no alteration in the appearance of the gluten. These and other experiments demonstrated the absence of a soluble proteo- lytic enzyme capable of degrading albumen or gluten. This led them to a consideration of the role played by the enzymes of the yeast which is used in bread-making. That gluten is attacked by yeast enzymes is shown by the following experiments : A quantity of flour was made into a dough with its own w'eight of water containing 5 per cent, of bakers’ yeast. The dough was left for four hours at 37° C., and the soluble nitrogen expressed as protein was found to be 2*7 per cent., calculated on the flour after corrections for pos- sible autodigestion of the yeast had been made. The same flour treated as above but without yeast w as found to yield only I *9 per cent, of soluble nitrogen as protein. This increase of nearly I per cent, must obviously be due to an enzyme other than erepsin since the latter, although present in yeast, is without action on gluten. It is probable that the physical char- acter of the gluten may be much modifled during the early stages of enzyme action without the production in large quantity of soluble decomposition products. In this connection may be noted the profound change in the viscosity of a starch paste under the influence of a trace of liquefying dias- tase before any maltose is produced. In common with other observers they regard the carbon dioxide con- cerned in the rise of bread, especially in the later stages of doughing and the early period of baking, as being formed from the fermentation of the maltose produced by the action of the diastase on the flour starch. That such sugar is maltose, they proved by the osazone test and the production of maltosazone. They have also observed that the diastase of some flours contains a liquefying enzyme; in others this is either absent or is unable to exert its influence. It might be supposed that the flour having the higher diastatic capacity w'ould be able to produce more maltose and therefore more carbon dioxide in a given time, and wwld be the stronger, but no such direct relation can be traced (see upper table, next page), another proof that gas retention rather than gas production is the more important factor. During the fermentation of dough the wTiters remark that the total volume of gas increases roughly as the strength, but a w'eak flour may have a diastatic power as- high as or even higher than a strong flour. Thus it appears that gas production is not a function of diastase ; but, as the following figures show, (second table, next page) there is a connection betw^een the gas volume and the additional matter rendered soluble during the process of dougliing. The cold w'ater soluble extract in a series of flours w^as estimated and also tlie soluble matter in their doughs, wLich had been kept at 40° C. for three THE STRENGTH OF FLOUR. 329 Flour. Amylolytic Power, Degrees Lintner. Bakers’ Marks. 14 57-0 90 z 40-0 90 X 34-0 40 2 32-0 78 3 30-0 80 V 27*0 90 U 26-0 91 Y 25-5 95 T 25-5 80 W 25*5 76 1 25-0 45 hours. Both sets of estimations were corrected for soluble nitrogenous substances present. The increase, measured by subtracting one from the other, can only be due to maltose formed by the action of diastase. Flour, j Per cent, of Matter soluble in Water at 15-5° C. 1 Per cent, of [ Matter soluble 1 in Dough when i kept at 40° C. for 3 hours. 1 Difference = Maltose formed during Doughing. Volume of Gas obtained from Dough in 3 hours. Bakers’ Marks. 1 212 3-60 1-48 78 45 X 203 4-41 1-38 84 40 w 2-83 5-38 2-53 145 76 3 2-49 5-53 3-04 155 80 Y 2-69 6.57 3-88 164 95 2 3-19 6-66 3-45 175 78 4 4-19 10-95 6-75 193 90 V ‘ 2-83 8-26 5-42 217 90 T 2-84 7-66 4-82 220 80 U 2-65 7-68 5-02 230 91 Z 3-54 11-65 8-11 270 90 It should not be forgotten that diastase, estimated in degrees Lintner, is solely saccharifying diastase, since soluble starch is the material acted upon, and the figure so obtained provides no measure of any liquefying enzyme. [Compare with experiments by one of the authors, given on page, 136.] It is well known that malt extract is frequently employed by bakers, presumably with the object of increasing the amount of sugar available for gas production. This, in our opinion, it does by providing a starch liquefying enzyme, the flours’ ovui diastase being adequate for saccharifica- tion. This view was supported by certain recorded experiments, and accordingly the writers considered that they might establish a connection between strength and the relative amount of a starch liquefying enzyme in a flour. If the gas production from weak flours (which is usually smaller than in strong ones) were relatively increased in a greater proportion by the addition of a trace of liquefying diastase, than in the case of flours vdth large gas productions, then they would have established the point that 1 The wheat of Flour 4 in this series was damped and dried before grinding. 330 THE TECHNOLOGY OF BREAD-MAKING. gas diastase ratio, total volume of gas, and incidentally therefore, to^ some extent strength, were functions of this Hquefying enzyme. The folio v'- ing results, in their opinion, justify this conclusion : — Flour. strength in Bakers’ Marks. Diastatic Power. Gas : Diastase Ratio. Gas Production in 3 hours, c.c. of Carbon Dioxide. Gas Production in 3 hours in presence of 0'25 per cent. Malt, c.c. of Carbon Dioxide. Percentage increase due to added Malt. X 1 40 34*0 ! 1 : 2-4 84 158 88-0 1 I 45 25-0 1 : 31 78 145 86-0 W i 76 25-5 1 : 5-6 145 194 340 2 78 320 ' 1 : 5-4 175 207 18-0 T ' 80 25-5 1 : 8-6 220 230 4-5 Z 90 40-0 i 1 : 6-7 270 250 nil. u 91 26-0 1 1 : 8-9 230 248 8-0 Y 1 95 25-5 i 1 : 6-4 164 235 490 This table shows that the percentage increase in gas volume due to the presence of liquefying diastase follows inversely the amount of gas originally liberated by the dough per se. The percentage increase is also inversely proportional to the bakers' marks, with the exception of Y. This flour, although highly marked, yields little gas, and it is of especial interest to note that, as might have been expected, its capacity for increase in presence of malt is considerable, thereby bringing it into line wflth other flours yield- ing small volumes of gas. In the case of Z, a flour giving the largest gas production of all, there is no increase in the volume of gas obtained by the addition of malt, and presumably, therefore, there is already present lique- fying enzyme in such quantity as not to be capable of serious augmentation by such a trace of malt as was used. The wTiters regard it as obvious that the strength of a flour must be closely connected with the gluten, although, no doubt, the presence of enzymes, soluble carbohydrates, and mineral constituents all play a part. They are further of opinion that there is strong presumptive evidence that the glutenin portion of the gluten molecule is that which possesses enzymic activity. (Jour. Soc. Chem. lud., 1908, 368.) Baker and Hulton's paper is marked by their recognition of the fact that the strength of flour depends on more than one factor. In connection with the enzymic activities of flour, they examined the effect of the proteo- lytic enzymes both of the flour itself and of yeast on gluten. It is of special interest to note the recognition they give to the possibilities of “ profound change " in physical character of substances such as gluten without any corresponding chemical changes in the ordinary use of that term. They also consider that the gas concerned in the rise of bread, especially in the latter stages of doughing and the early part of baking, is derived from the starch of the flour. Gas retention is recognised by the writers as more important than gas production. Careful attention was given to the amylo- lytic enzymes of flour, and especially to the presence or absence of a lique- fying enzyme. This they regard as having an important bearing on strength, and produce results in support of their conclusion. The difference in activity of flour diastase to soluble starch and starch paste respectively was made the subject of experiments by one of the authors, and recorded in the 1895 edition of this work. In summarising their conclusions, the writers emphasise the fact of its close connection with gluten. THE STRENGTH OF FLOUR. 331 463. Flour Composition, Shutt. — In a bulletin issued by the Government of Canada, Shutt gives his conclusions based on the results of analyses of forty-two samples of flour, as to the bearing which the gliadin and other constituents have upon the baking value of flour. The results obtained show that whilst there is a distinct relationship between the protein, gliadin, and wet and dry gluten, there is no evidence of a definite or absolute ratio. The gliadin value is not definitely related either to the nitrogenous com- pounds or to the “ baking strength.'" The determinations of the nitro- genous compounds are nevertheless of great importance in judging the value of a flour for bread-making purposes, especially when the physical character of the gluten is taken into account. There is no apparent rela- tion between the ratio of total ash to protein and “ baking-strength," nor between the ratio of ash in gluten to protein and “ baking-strength." [Canadian Dept. Agric. Bull., 1907 [57] 37.) Shutt is unable to find any definite ratio between ghadin and other nitrogenous compounds or strength. He also emphasises the importance of taking into account the physical properties of the gluten. Further, he is unable to discover any relation between total ash and strength or ash in gluten and strength. 464. Sugar in Wheat Flour, Liebig— Liebig states that the sugars in wheat flour are glucose and sucrose, the respective quantities being 0*1- 0*4 and 1-1*5 per cent, calculated on the dry substance. By means of a diastatic enzyme, maltose is formed on digesting the flour with water, and also in the dough. On maintaining dough at a temperature of 30-40° C. for fourteen hours, 4*6 per cent, of reducing sugar (reckoned as glucose) were formed. The sucrose content on the other hand remains fairly con- stant. The diastatic power (Lintner) of a wheat flour was in the case of dark coarse flours about one-third of that of an average malt, and about one-seventh in the case of fine flours. These are values with soluble starch ; the starch-liquefying power is insignificant compared with that of malt diastase (Lander, Jahrhh., 1909, 38, 251.) Liebig also recognizes the lack of starch-liquefying enzyme in flour as compared vdth malt. 465. Present-day Conclusions.— In paragraph 436, in the early part of this chapter, it is laid down that there must be a sufficiency of sugar or other material available for fermentation in the dough. In what may be referred to as the summary of views current in 1895, it is suggested that the presence of much maltose is evidence of unsoundness, and reference has already been made to the fact that certain very strong flours contain com- paratively little sugar, while in others which are weak sugar is present in comparatively large quantity. Flours from sprouted wheats are com- paratively weak and with high maltose contents ; in such cases there is probably practical agreement Avith the view that the high sugar is’asso- ciated Avith low strength. If wheat is gathered and milled in an unripe condition, there is again a lack of strength, and yet there is a relatively high percentage of sugar. Thus in the account given in paragraph 427 of Teller’s researches on the composition of wheat at different stages of ripe- ness, it is shown unripe wheat contains more sucrose, 2*95 to 1*43 per cent., than ripe wheat at I *44 per cent. (There is one rather anomalous figure, viz. 1*28 per cent, for the third day immediately preceding ripeness). Parenti states (paragraph 446) that the reducing sugar of flours is reduced during fermentation from 2*31 to 0*13 per cent., that is a consumption of 2*18 per cent. In Wood’s paper, paragraph 453, he lays great stress on the importance of sugar as a factor of strength, and remarks of one flour, G that it cannot make large loaves because of the low percentage of sugar 332 THE TECHNOLOGY OF BREAD-MAKING. present. He accordingly tested the flours by a fermentation test, and 20 grams of flour and 20 grams of water (112 quarts to the sack) and 0*5 grams of yeast (7 lbs. to the sack) were taken and fermented at 35° C. (95° F.) for twenty- four hours, at the end of which time the volume of gas was observed. In the case of the lowest flours, G and L^, there was a gas equivalent of 1*6 per cent, of sugar, while the highest amounted to 2*6 per cent, of sugar. The flour G is that before referred to as being deficient in sugar. Armstrong states yet more deflnitely that the amount of sugar actually present in flour is not sufficient to give the necessary volume of gas required in bread-making. Again, Ford and Guthrie are of opinion that the greater part of the carbon dioxide liberated in panary fermentation must be derived from the starch of the flour. They quote an experiment in which on fermenting a flour in the usual way with yeast they obtained 350 c.c. of gas from 20 grams of flour, which corresponds roughly wuth the fermentation of 1*3 gram of sugar or 6*5 per cent, of the flour. Direct estimations gave respec- tively 0*82 per cent, of sucrose and 0*1 per cent, of reducing sugar in the flour, special precautions being taken to eliminate all diastase from the flour before the determination. Baker and Hulton also express the opinion that the carbon dioxide concerned in the rise of bread during the later doughing and the early period of baking has as its source the starch of the flour. 466. Fermentation Experiments by Authors. — In view of these opinions it was thought advisable by the authors to make some fermentation experi- ments which should be as nearly as possible conducted under precisely the same conditions as occur in actual practice. A baker was asked for samples of respectively the strongest and weakest flours he then had in stock, and supplied the following : — A. A strong Spring American Patent Flour. B. A very weak French Flour. Doughs were made from each of these in the follovdng manner : — A Flour, 200 grams at 17° C. Salt, 2 grams. Yeast, 1 gram. Water, 100 grams at 31° C. B 203 grams at 17*5° C. 2 grams. 1 gram. 100 grams at 31° C. Dough, 303 grams at 26° C. 303 grams at 26*5° C. The following are the proportions of each ingredient per sack — salt, 2 lbs. 13 oz. ; yeast, 1 lb. 6f oz. ; and water, 56 quarts. After being made, the doughs were transferred to enamelled steel beakers and weighed ; after fermentation they were ing results : — again weighed with the follow- A B Weight of unfermented dough .. 301-6 298-7 ,, ,, fermented dough . . . . 299-8 296-6 Loss in weight during fermentation . . 1-8 2-1 Immediately after being weighed, each beaker was placed in a contain- ing vessel of convenient size, and the lid fastened down so as to make an air-tight joint. This vessel was in turn submerged in a water-bath main- tained at a constant temperature of 25° C. (77° F.) and fermentation was allowed to proceed for six hours. To the containing vessel was attached a leading tube through which the generated gas passed, and was collected THE STRENGTH OF FLOUR. 333 over brine and measured in the usual way. (The whole apparatus is described in paragraph 612, Figure 43.) The times and temperatures vere practically copied from those in actual use, and covered the whole period to the arrestment of fermentation in the oven, they were in fact the same as those which the baker employed when working with flours of this stronger type. The volume of gas was read at the expiration of one and a half-hours and every half-hour until the six hours had elapsed. The results are recorded in the following table. The gas was collected at a temperature of 18*0° C. and 760 m.m. of pressure. Time. A. Strong Flour. Gas Evolved. B. Weak Flour. Gas Evolved. Total. Per IlalMiour. Total. Per Half-hour. Start . . 0-0 0-0 IJ hours 40 - 0 ') 35 - 0 , 1 23 I 36 ■2 „ 63 - 0 ) 1 71 - o | j 47 1 ( i 54 2i „ llO-Ot 125-0 1 47 1 I 70 3 „ 157 - 0 . 195-0 1 59 1 ^ ' 82 3 ^ 5 , 216-0 277-0 1 1 r 80 ^ 100 4 „ i 296-0 1 377-0 1 1 1 1 1 r 87 1 1 ; ' 105 ,, 383-0 482-0 1 1 117 1 1 t ^ 125 5 „ 500 -C 607 - 0 ^ 1 1 j 92 140 5i „ 592-0 1 747 - 0 ; j 1. j 113 136 6 „ 705-0 ' 883-0 1 From the volume of gas evolved, its weight, and that of the sugar re- quired for its production, are easily calculated. The results of such calcula- tions are given in the upper table on the folio wdng page. In each pair of columns the first contains the various data as calculated on the dough as used ; in the second column they are reckoned as percentages of the dried or water-free solids of the dough. In view of the very small loss of weight by the dough during fermentation, it must be assumed that very nearly all the alcohol remains in the dough and is weighed therewith. A number of analytical determinations were also made on the flours and doughs at the close of fermentation respectively, the results of which appear in the lower table on page 334. For soluble matters 10 per cent, solutions of the flours were prepared, allowed to stand for half-an-hour in the cold, and filtered bright. No attempt was made to discriminate between previously existing sugars and those produced from the starch during this period of stand- ing, as sugars from the both sources are in practice equally available for gas production from the start of the fermentation. With the fermented doughs, these were kneaded until as much as possible of the gas had been forced out ; 50 grams were then taken, and washed for gluten in successive smafl 334 THE TECHNOLOGY OF BREAD-MAKING. Doughs. Particulars. A. Strong Flour. B. Weak Flour. 1 1 As Used. Dried Solids. 1 As Used. Dried Solids. Total volume of gas evolved in c.c 705 883 Weight of gas evolved (CO 2 ), in grams Approximate weight of sugar required for 1-30 — 1-63 — the production of the gas, in grams Approximate weight of alcohol produced, 2-82 — 3-53 in grams Weight of sugar required per 100 grams of 141 i 1-76 dough, i.e. per cent. . . Weight of alcohol produced per 100 grams 0-93 1-58 M8 2-05 of dough, i.e. per cent. Loss of weight during fermentation, per 046 0*79 0-59 1-02 cent. Sum of the two preceding quantities, which practically agrees with sugar 0-59 1-00 0-70 1-22 1 required 1-05 ‘ 1-79 L29 2-24 A. Strong Flour. Constituents. j i Flour. Fermented Dough. As Used. ! Diisd Solids. As Used. Dried Solids. Moisture 11-29 1 41-11 _ Total Solids 88-71 ’ 100-00 58-89 100-00 Gluten, Wet j 40-5 * 45-64 29-90 50-77 „ Dry 1 13-5 ! 15-21 9-54 16-20 ,, Ratio of Wet to Dry 3-0 3-0 3-1 3-1 „ True 10-23 11-53 7-32 12-43 ,, ,, Percentage of Dry . . 75-57 75-57 76-67 76-67 Soluble extract 6-12 6-90 4-12 6-99 Reducing Sugars as Maltose 1-48 1-67 1-00 1-70 Non-reducing Sugars as Sucrose . . j 0-93 1-05 Nil Nil Added Salt — 1 0-66 1-12 B. Weak Flour. Moisture . . . . . . . . 13-50 1 42-58 Total Solids . . . . . . 86-50 100-00 57-42 100-00 Gluten, Wet 30-5 35-26 22-22 38-68 ,, Rry 11-1 12-83 7-10 12-36 ,, Ratio of Wet to Dry 2-7 2-7 3-1 3-1 n . True 8-74 10-10 5-89 10-25 ,, ,, Percentage of Dry Soluble Extract 78-74 78-74 83-04 83-04 5-76 : 6-66 5-44 9-47 Reducing Sugars as Maltose 1-17 1-35 1-30 2-26 Non-reducing Sugars as Sucrose. . 0-21 0-24 , 0-10 0-17 Added Salt — 0-66 1-15 THE STRENGTH OF FLOUR. 335 quantities of tap water (from deep wells in the chalk). The washings were added together and made up to 500 c. c.,mcluding the starch, for the presence of which no correction was made. This solution was filtered bright and soluble matters estimated in the filtrate. It is interesting to place on record that on washing the dough with distilled water, at the end of the second wash- ing the gluten, which at first separated out very well, became completely disintegrated. There was no tendency in this direction when tap water was employed. Baking tests were also made on the flours with the following results : — In each case 24 oz. of flour were taken. With A, 13 J oz. of water were required to make the dough, and with B, 12 oz. of water. With these quan- tities the consistency of the two doughs was the same. They were worked with the same quantities of yeast and salt, and at the same temperature. The dough from A was springy, tough, and wiry ; that from B was dead and putty-like. The A dough was ready for the oven in five hours, and B in four hours. They were baked into crusty loaves, and awarded bakers" marks for strength, on the scale of maximum 100, minimum 50. The awards were A, 95, B, 60 marks. If there was any error it was in the direction of undue generosity to B. The difference in water-absorbing capacity is equivalent to 17*5 lbs. or 7 quarts to the sack 'of 280 lbs., and this figure agrees with the vendor baker’s estimate of the water-absorbing power of the two flours in practice. 467. Consideration of Results. — In examining the results, the first subject is naturally that of the gas evolved. The quantity obtained from the strong flour must be regarded as amply sufficient to ensure the production of a bold well -risen loaf. The evolution increased until the end of the fifth hour, when for one reading there Avas a diminution. The slight irregu- larities were apparently due to the sudden liberation of gas by the “ drop- ping ” of the dough. The sugars obtained by direct extraction of the flour by cold water, 2*72 per cent. Avere considerably in excess of the amount required in order to produce the evolved gas, viz. 1*58 per cent. In each case, and throughout these comparisons, the percentages on the dried solids are taken. Turning next to the Aveak flour, there is considerably more gas evolved over the Avhole process of fermentation, and even to the end the evolution is more rapid than A\Ith the strong flour. The gas Avas evolved much more regularly, because, no doubt, of the less retaining poAA'er (greater porosity) of the Aveak dough. The total sugars of this flour amounted to 1*59 per cent, and are less than those required for the fermentation, viz. 2*05 per cent., by 0*46 per cent. Against this it must be remembered that AAuth such a very weak flour a much shorter period of fermentation AA’ould be essential to the production of a moderately passable loaf, than AA^ould be employed Avith the stronger flour. A baker Avould probably give it no more than from tAA^o-thirds to four-fifths of the amount of fermentation that Avould be employed for the strong flour. If the dough AA^ere got into the oven at the end of the fifth hour, 607 c.c. of gas AA^ould have been evolved, as against 588 c.c., which amount is tAvo-thirds of the 883 c.c. produced in six hours. This latter amount of gas requires for its production 1*37 per cent, of sugar as expressed on the dried solids of the dough, leaving a margin of 0*22 per cent, surplus of sugars in the flour. Taking these as extreme types of strong and Aveak flours, the pre-existent sugars of flour, together with those readily-formed in the cold on the addition of water, are in themselves sufficient for the production of all gases necessary in the normal fermentation of dough. Comparing the above conclusion AAuth those previously cited, Parenti notes a consumption of 2*18 per cent, of the flour, amounting to about 2*45 per cent, of the dried solids, AA'hile in the case of the authors’ very strong flour, 1*58 per cent, only of sugars Avere required. Judging by recognised 336 THE TECHNOLOGY OF BREAD-MAKING. English methods, Parenti's doughs were considerably over-fermented. In Wood’s fermentation tests, volumes of gas ranging from 131 to 345 c.c. were obtained from 20 grams of flour. Multiplying these numbers by 10 in order to compare the results with those obtained by the authors from 200 grams of flour, there is a minimum of 1,310 c.c. as against a working re- quirement of 705 c.c. with a strong and about 600 c.c. with a weak flour. Similarly, when Ford and Guthrie produced 350 c.c. from 20 grams of flour (or 3,500 c.c. from 200 grams), they obtained about five times as much gas as is evolved in the normal fermentation of dough. If in flours of ordinary type, whether weak or strong, there are always sufficient pre-existent and readily-formed sugars for the usual require- ments of fermentation, it is not very apparent that any excess of amylolytic enzymes over those necessary for the production of such readily formed sugars, has any direct bearing on the strength of the flour. (And the enzy- mic activity of all flours seems sufficient for this particular purpose.) But so far as these recent experiments go, the following calculations are of interest : — A. Strong Flour. B. Weak Flour. Soluble Extract in Fermented Dough 6-99 9-47 Subtract added Salt . . 0-66 0-66 6-33 8-81 Add Sugar consumed in Fermentation 1-58 2-05 7-91 1086 Substract Soluble Extract of the Flour . . 6-90 G66 Soluble Matters produced during Fermentation . . I-OI 4.20 In these particular instances there is, during ordinary fermentation,. over four times as much diastatic action with the weak than there is with the strong flour. This result seems to be borne out by general experience for strong flours are liable to produce dry flavourless bread, while that from the weaker varieties is more usually moist and sweet. Humphries informs the authors that with the flours of some very hard, ricy wheats, there are insufficient pre-existent and readily -formed sugars to yield the quantity of gas produced in even the limited fermen- tation here described. It is suggested that such flours are, however, scarcely commercial varieties in their separate state. 468. Gas-retaining Power. — Comparatively recently the opinion has been expressed that the strength of flour depends not upon its gas-producing but on its gas-retaining power. This is only another way of formulating the old view that strength depends on the gluten of the flour. 469. Relation between Gluten and Proteins of Flour. — The foregoing researches serve to throw considerable light on the actual composition of gluten and its relation to the total proteins of the flour. Norton made a very complete analysis of crude gluten, which he found to contain about 74 per cent, of gliadin and glutenin, and about 7 per cent, of a non-gluten protein. • The remaining 19 per cent, was made up of fat, carbohydrates, fibre, and mineral matter. These figures confirm the opinion in the 1895- edition that crude gluten contains about 80 per cent, of proteins as deter- mined by nitrogen estimation. Norton points out that the percentage of crude gluten from flour roughly approximates to that of total protein present, there being a loss of non-gluten proteins, more or less balanced THE STRENGTH OF FLOUR. 337 by the retention of non-protein matters ; in his view evidently the pro- portions of the two are regarded as being fairly constant. In consequence he regards crude gluten as but a very rough expression of the protein con- tent, and the determination as of but little worth in the valuation of flours. Chamberlain goes over much the same ground, and substantially agrees with Norton. He flnds about 75 per cent, of proteins, and 25 per cent, of non-proteins in crude gluten. Of all the proteins present in wheat 60 to 65 per cent, are found in the gluten, and 35 to 40 per cent, are lost in the washings. Evidently all the bran proteins must of necessity be thus lost. He agrees that the balance of losses of proteins and retention of non-proteins make the gluten estimations agree roughly with the total proteins calculated from total nitrogen. A further and more important conclusion is that gluten contains less total protein than the sum of the ghadin and glutenin present in the wheat by about 15 per cent. ; and con- sequently that the loss of proteins in the determination of gluten is at the expense of gliadin or glutenin, the true gluten proteins of wheat. He - therefore regards gluten determinations as not being able to yield any information that cannot be obtained from determinations of total pro- teins and alcohol-soluble and insoluble proteins. If Norton's and Cham- berlain's results both be regarded as accurate, Chamberlain's 15 per cent, loss would have to be increased by the 7 per cent, of globuhn contained in the gluten, which is included in the total proteins, but is neither gliadin nor glutenin. Dealing however with the 15 per cent, loss only, in the case of a flour yielding 39 per cent, of wet gluten, and 13 per cent, of crude dry gluten, such weights ought to have been, had there been no loss, 44*85 per cent, of wet, and 14*95 per cent, of dry gluten. The question suggests itself, to what is such loss due ? Is it caused by an actual failure to recover some 6 per cent, of wet gluten that was present in the dough and necessarily lost in the washing ; or at the time of washing was this gluten, or its com- ponents gliadin and glutenin, in a non-elastic and non-adhesive condition, and therefore not gluten at all in the sense of possessing the physical pro- perties of wet gluten ? To the authors, the latter alternative seems the more probable, and consequently there may be present in dough, gliadin and glutenin constituents Avhich at the time of making the estimation are not fulfilling the physical functions of gluten proper in the usually accepted sense of the term. Some light is thrown on this point by the gluten deter- minations made on the flours used for the fermentation experiments just described. That of the strong flour. A, was when washed at the end of an hour’s standing, and dried, 15*21 per cent, of the dried solids. The corresponding fermented dough yielded 16*20 per cent. In the case of the weak flour, however, there was a » slight diminution in the dry gluten of the fermented dough. Nitrogen determinations were accordingly made on the whole four dry glutens, and the results calculated into “ true gluten.” These figures are included in the foregoing table on page 334. The true gluten obtained from the fermented dough of the strong flour is 12*43 as against 11*53 per cent, on the flour. There is also an increase with the weak flour, the figures being 10*25 on the dough as against 10*10 per cent, on the flour. During fermentation therefore the quantity of proteins which possess the physical character of gluten show an increase. Recent research must therefore be regarded as confirming the veiw that crude gluten contains from 20 to 25 per cent, of non-proteins. Further, it goes to show that about 7 per cent, of the proteins present may be non-gluten protein, and that of the gluten proteins (gliadin and glutenin) some 15 per cent, of the total in the wheat or flour are not obtained in the gluten. Obviously, a dry gluten determination must not be regarded as an estimation of the proteins of the wheat or flour. 338 THE TECHNOLOGY OF BREAD-MAKING. The above limitation being accepted, the question naturally arises as to what a gluten determination really is. The best answer seems to be that a gluten determination is an estimation of the amount of those bodies which are in such a physical condition as to impart elasticity and gas-retaining power to the dough at the time when the determination is made. The exact nature of its constituents is of secondary importance, and whether gluten consists of protein matter only, or of 75 to 80 per cent, of proteins together with a complement of non-proteins, does not affect the value for the purposes of comparison of the results obtained. A point worthy of consideration about gluten estimations is wliether they might not be advantageously made on the dough at a stage of its fermentation when its strength is of the greatest importance. That stage by general consent w^ould be when the dough is ready to go into the oven. This end might be attained by making the flour to be used for this estimation into a dough with yeast, salt, and water, in the proportions and at the temperatures employed in actual bread-making. The doughs w^ould then be kept in a fermenting vessel at a constant temperature, such as that employed in the recently described experiments, for a time similar to that taken in the bakehouse for the completion of the fermentation of the dough. In order to prevent drying, the atmosphere of such a vessel should be kept saturated with mois- ture. If the gas evolution were simultaneously observed a still more com- plete record of the behaviour and properties of the flour w^ould be obtained. 470. Mechanical Disintegration of Gluten. — It is a fact well-known in the experience of bakers that mechanical over-kneading kills, or “ fells,” a dough. The consequence is that a dough, which w^ould ordinarily pro- duce a bold w^eU-risen loaf, becomes soft and putty-like, and yields small sodden bread, just as through a very weak flour had been used in its pre- paration. In practice, any serious injury from this cause is avoided by careful watching ; further, the dough has wLile standing the pow'er of recovery in some degree of its strength. It is not so well-known that such over-kneading materially alters the physical character of the gluten. In order to investigate the point, the following experiments were made w ith a very strong American wheat flour. No. 1. The flour was made into a dough by hand-kneading, and the various determinations carried out on the gluten from this dough. The total soluble matter and proteins soluble in water w^ere determined direct on the flour. The w^ater absorption by viscometer was determined on hand-made doughs, and amounted to 70 quarts per sack. Nos. 2 and 3 w'ere machine-made in the manner described. No. 2. Water w'as taken in the proportion of 66 quarts to the sack. The machine w^as turned until the flour and water w ere incorporated : 30 additional revolutions were then given. The dough stood an hour, and was then passed through the viscometer. The time is given below. For gluten and other determinations 31*8 grams of dough w^ere taken at tlie close of the hour, being equivalent to 20 gram-S of flour. The water used for w'ashing gluten was reserved and made up to 1,000 c.c. On this solution, the soluble proteins and other soluble matter were determined. No. 3. Water w^as again taken in the proportion of 66 quarts to the sack. After incorporation, 250 revolutions were given to the machine. The dough stood one hour, and w'as then passed through the viscometer. It W’as then returned to the machine, and received another 250 revolutions. The dough w'as now" very sticky to handle, and w’as once more tested by the viscometer. It was again returned to the machine and subjected to another 250 revolutions. By this time it w as much more sticky, presenting THE STRENGTH OF FLOUR. 339 in fact the appearance of bird-lime. The dough could be drawn out into long threads, was very moist, and in fact appeared as though it contained much more water. The following are the viscometer results : — No. 2. No. 3. After one hour After another 250 revolutions After a further 250 revolutions 873 seconds. 520 seconds. 16 7 In No. 3, compared with No. 2, there is a marked diminution in water- absorbing power. But with the further kneading, No. 3 dough became altogether altered in properties, and had in fact entirely lost the charac- teristics of a bread-making dough. Effect of Mechanical Treatment on Doughs. No. 1. 1 No. 2. No. 3. Wet Gluten 42-30 37-10 35-45 Ratio of Wet to Dry Gluten 2-8 2-9 3-1 Dry Gluten 15-02 12-70 11-44 Non-protein Matter in Dry Gluten. . 4-25 1-40 0-92 True Gluten . . 10-77 11-30 10-52 Gliadin ex Gluten . . . . . . 7-36 7-19 i 6-24 Glutenin ex Gluten, by difference . . 3-41 4-11 4-28 Percentages on Dry Gluten. Non-protein Matter in Dry Gluten 28-29 11-02 8-04 Gliadin 49-00 56-61 54-54 Glutenin 22-71 32-37 37-42 Total Proteins . . • . . 12-95 12-95 12-95 Proteins soluble in Water . . 1-49 1-26 1-56 ,, recovered as True Gluten 10-77 11-30 10-52 ,, lost in washing Gluten 0-69 0-39 0-87 Gliadin ex Flour 6-43 6-43 6-43 Glutenin ex Flour, by difference 5-03 — — - Percentages on Total Proteins. Proteins soluble in Water. . 11-50 9-73 12-04 ,, recovered as True Gluten 83-16 87-26 81-23 ,, lost in washing Gluten. . 5-34 3-01 6-73 Gliadin ex Flour . . 49-65 49-65 49-65 Glutenin ex Flour, by difference ! 38-85 — — Non-protein Matter soluble in Water 3-35 5-82 6-00 On making gluten tests. No. 2 yielded less wet and dry gluten than No. 1, but washed quite normally. The true gluten was slightly the higher, showing that the loss in washing was almost entirely non-protein matter. On proceeding to wash gluten from No. 3, the whole dough broke down into a flocculent and non-coherent mass. It was only by pouring this on to a sieve, and collecting by pressing the particles together, that any gluten was recovered. When thus obtained the gluten was soft and flabby and possessed scarcely any coherence or elasticity, whereas those of Nos. I and 2 were tough and resilient. Although so profoundly altered in physical character, the chemical composition of the gluten does not show corre- spondingly great changes, the principal being a diminution in the gliadin, 340 THE TECHNOLOGY OF BREAD-MAKING. which was estimated by the “ starch method.’' (See Chapter XXVIII). Determinations were made on the collected washing water, but these can- not be regarded as perfectly accurate, since some loss is inevitable. They may however be taken as comparative between Nos. 2 and 3. A decidedly greater amount of protein was soluble in water in No. 3 than No. 2. The total loss of protein in washing was also higher, though in none of the experi- ments was the loss very great. The whole of the results are set out in detail in the following table. They go to show that not only is the gluten phy- sically altered, but there is some change also in solubility in various media. In addition to the alteration in the gluten, there is a considerable increase in the amount of soluble non-protein Kiatter. The interesting point of these experiments is that by simple m-echanical attrition of the dough, profound changes are made in the character of the gluten and apparently in the same direction as those which result from treatment mth dilute acids as carried out by Wood. The authors are conducting a systematic investigation of the effects produced on dough and gluten by mechanical treatment and hope at an early date to make a communication on the subject. 471. Relation of Gliadin Ratio to Strength of Flour. — With Osborne and Voorhees’ demonstrations of the insoluble proteins of flour consisting of gliadin and glutenin, a very natural development of inquiry was along the lines foreshadowed in the 1895 edition of this work, and consisting of determinations of the total amount of each of these present in a flour, and the ratio such amounts bore to each other. Guthrie, Fleurent, Snyder, and others have contributed to this research, and each has employed methods of determination mmre or less original. A consequence is that different proportions of the total protein is returned as gliadin or glutenin according to the process adopted, and as a result differing conclusions have been formed as to the m.ost desirable ratio between these bodies. Guthrie ob- tained from about 59 to 78 per cent, of gluten as glutenin (which figure also includes the non-proteins). He concludes that a preponderance of glutenin is preferable, and that increased gliadin produces a weak, sticky, and in- elastic gluten. With a totally different m_ethod of extraction, Fleurent found his best results with 25 per cent, of glutenin to 75 per cent, of gliadin, and a deterioration with a departure in either direction. Guess extracted his gliadin direct from the flour, and without any limitation found that the more gliadin present, the more elastic and better was the gluten. Snyder places on record that the alcohol-soluble portion of flour protein (gliadin) may vary from as high as 70 to as low as 45 per cent. Avith only minor varia- tions in the size of the loaf or the bread-making value of the flour. Further lie regards gliadin as not being of uniform composition. In Chamberlain’s opinion, so-called gliadin contains also albumin and globulin. Wood finds that flours which are at the extreme ends of the scale of strength may have substantially the sam_e proportions of gliadin to total nitrogen. Snyder in fact shows that widely different gliadin contents may occur in practically identical flours : Wood supplements this by showing that widely different flours may be practically identical in their gliadin contents. In other words, glutens containing the same proportions of gliadin and glutenin may be either weak or strong. The natural conclusion is that strength or weakness is independent of the ratio of gliadin to glutenin in the gluten. As gluten is not subjected to the solvent action of 70 per cent, alcohol in the process of bread-making, it does not seem that it would necessarily follow that a connection must as of course exist between the degree of solu- bility in that reagent and the strength of the flour. Gluten is probably a loose compound of gliadin and glutenin in varying THE STRENGTH OF FLOUR. 341 proportions, and its qualities as a whole, from the bread-making stand- point, are apparently not closely related to its protein composition. For its marked differences in properties, the most likely explanation is that they are based on variations in physical rather than chemical character. This fact has been recognised by Baker and Hulton, who in discussing emzyme action on gluten remark that “ the physical character of the gluten may be much modified during the early stages of emzyme action without the production in large quantity of soluble decomposition products. In this connection may be noted the, profound change in the viscosity of a starch paste under the influence of a trace of liquefying diastase before any maltose is produced.'’ Strength, then, must he regarded as depending on the quantity and physical character of the gluten of the flour. 472. Conditions affecting the Quantity and Physical Character of Gluten. — These naturally constitute the subject of the next line of inquiry. As to quantity, that is largely a question of selection of seed and circumstances of cultivation, and therefore mostly lies outside the scope of the p 4 ;esent work. Much careful and successful research has, however, been devoted to such questions as the choice of seed, and effect of soil, climate, and man- uring, on the development of the gluten content of wheat. But the miller and baker (in those capacities) have only to manipulate and do their best with wheats and flour as they find them. Turning next to the ques- tion of physical character and how it may be modified, that also is a pro- blem which largely lies within the domain of the agriculturalist and his advisers rather than the miller and baker. Again, the choice of seed and other factors previously mentioned have a most important bearing on the subject. In particular, the researches of Wood have evidently been conducted with the object of assisting the farmer in gromng strong wheats, and with a full realisation of limits and possibilities which do not so much concern the subsequent handlers of wheat and flour. Among the factors w^hich have been suggested as modifying agents on gluten are sugar, pro- teolytic enzymes, acidity, and certain mineral salts of the wheat or flour. Sugar has already been discussed, and reference has been made to its power of increasing the proportion of gluten which is soluble in 70 per cent, alcohol. Ford and Guthrie point out that certain flours contain a proteolytic enzyme which has an extremely detrimental effect on the tenacity of the gluten, and described methods by which this body can be detected. Baker and Hulton have also investigated the matter of the presence of proteolysts in flour. They, however, came to the conclusion as far as concerned the flours examined by them, that there was no soluble proteolytic enzyme in flour capable of degrading albumin or gluten with the production of soluble nitrogenous bodies. They And, on the other hand, that the gluten in dough is attacked by yeast enzymes, with an increase in the amount of soluble proteins. It is in this connection that they make the remark before quoted as to the possibility of profound physical changes in gluten, with no (or but little) chemical change. Fermentation, as already shown, may increase the quantity of protein recoverable as gluten ; it also possesses the property of materially, softening that body, and at the same time in- creasing the amount of protein which while insoluble in water is soluble in 70 per cent, alcohol. The following results were obtained on a flour by the authors. The percentage of constituents is calculated on the dried sohds of the flour, and the fermented dough respectively : — Dry Gluten Flour. . . 12-14 Fermented Dough. .. 11-08 True ,, (Proteins) . . 10-33 . . 10-14 Ghadin ex Gluten . . 2-80 3-20 Glutenin . . 7-53 6-94 Ratio of Gluten to Gliadin . . 2-7 2-2 342 THE TECHNOLOGY OF BREAD-MAKING. Any reagent or action by which this change is assited is therefore aiding in the development of the strength of the dough, provided such changes are not thereby carried too far, since the weakness of an over- worked dough is probably due to the same causes as those which are bene- ficial in a lesser degree. Although strength seems independent of the original proportions in which ghadin and glutenin exist in a flour, yet those changes during fermentation which result in increased elasticity of the dough are usually accompanied by an increase in the alcohol-soluble content of the gluten. Both sugar and proteolysts may therefore in this manner exert a beneficial influence on the dough. Snyder finds that any shght increase of acidity in the grain diminishes the percentage of gliadin (paragraph 448). On the other hand, Wood (paragraph 455), finds acidity to have no relation to strength. Wood states that certain acids in small quantity have a marked disintegrating action on gluten, which effect increases with the degree of acidity, until vith further concentration a reverse action occurs, and at a certain point the effect of the acid is to harden the gluten and render it more elastic and coherent than was its original condition. Other acids show no such reverse action, but up to any hmit of concentration effect a disintegration which becomes more rapid as the acidity increases. These results are de- scribed in detail in paragraph 455. It is difficult to say whether in actual dough fermentation the effect of acid on gluten is in its earher stages capable of inducing beneficial changes thereon. At the later and overworked stages, the acid developed is probably one of the factors in carrying the changes in gluten to a condition of less gas-retaining power. 473. Effect of Mineral Salts on Gluten. — Wood has made a series of most important investigations as to the effect of certain mineral salts on gluten. For a description of these in detail, the preceding abstract of his paper must be referred to (paragraph 455). His most recent conclu- sions are embodied in a personal communication from Professor Wood, kindly made for the purposes of this book, and contained in paragraph 459. One point may be mentioned in connection with these experiments. As Wood immersed his gluten in solutions of acids and salts in pieces about the thickness of a pencil, it took forty-eight hours for such pieces to become permeated with the solutions. He therefore expresses the opinion that it would be impossible to check them by experiments on dough, since the latter could not possibly be allowed to stand that length of time before baking. But this objection would probably not be so serious as Wood antici- pates. The reason why forty-eight hours are required for the gluten is the extreme slowness with which solutions can diffuse through a mass of gluten. In making corresponding tests with flour, it is not necessary to immerse the dough in the solutions, as the salts can be mixed in the finely powdered form with the flour itself before doughing. Or still better, they could be dissolved in the requisite proportions in the water used for doughing pur- poses. Fermentation could then be allowed to proceed in the ordinary manner, and observations made during the progress, and on the baked loaf. In determining wLether a wheat shall be weak or strong. Wood is of the opinion that the effective action of beneficial salts occurs during the growth of the grain, while the endosperm is being formed and is in a comparatively milky stage. In order to improve wheat at this stage, the SE^lts must evidently be obtained from the soil. Experiments made by Chitty and one of the authors go to show that wheats may be improved in this direction, when in the hands of the miller, by treat- ment of the grain itself (paragraph 652). Additions to the flour as flour, or at the time of doughing, are also capable of effecting material improvements. Interesting examples of this are the at one time prevalent THE STRENGTH OF FLOUR. 343 addition of alum when flours were exceedingly weak, and the baker’s well- knoAMi expedient of using an extra quantity of salt with a very weak flour. Though the former addition is condemned on other grounds, its undoubtedly considerably improved the strength of the flour. So, too, salt has a decided ” binding ” effect on a weak and runny dough. The problem cannot at present be regarded as completely worked out, but the results already obtained, confirmed as they are by practical experience, go to show that the presence or absence of certain mineral salts is a most important factor in deter- mining the strength or weakness of gluten and consequently of flour. Bearing in mind that flour of itself is toxic to some varieties of yeast, and that certain mineral salts act as an antidote to the poisonous action, it is of interest to note that some mineral salts increase the strength of gluten. Indirectly they may further benefit the working properties of a flour by nullifying its toxic action to yeast. 474. Gluten Determinations. — ^From the foregoing expressions of opinion, it vlll be gathered that the authors continue to attach importance to properly conducted gluten determinations. The estimation of wet gluten is a mea- sure of the amount of that constituent of flour, which by its physical char- acter determines the quality and nature of the resultant dough and bread. It further determines this in a way which is comparatively easy of per- formance and affords results which are readily understood by all concerned. In the hands of an expert flour valuer, not only the quantity of gluten, but its appearance and general characters give most valuable indications as to the tjrpe and quality of a flour, even though they cannot be expressed in percentages or other forms of figures. The following remark of Saunders is an interesting confirmation of the practical value of the gluten test : — “ In addition to the final baking tests I have used for several years a simple chewing test (taking only a few kernels of wheat) as a valuable guide to gluten strength and probable baking strength in the earlier stages of selec- tion. This test was advocated as an essential aid in the selection of cross- bred varieties of wheat in the Bulletin on Quahty in Wheat, pubhshed at Ottawa, October, 1907.” {Supplement 4, June, 1910, p. 29, Jour. Board of Agriculture.) CHAPTER XVI. CHEMICAL COMPOSITION OF FLOUR AND OTHER MILLING PRODUCTS. 475. Properties. — Among the general properties of flour, that of Strength has been deemed of suflicient importance to warrant its treatment in a separate chapter. Flour also possesses certain other physical characters of which some explanation must be given. These include Colour and Water- absorbing power. For scientific purposes it is necessary to have not only means of judging and comparing these, but also some method of registering for future reference, and for the institution of comparisons between the results obtained by one observer and those of another. In order to do this, these properties must in some way be expressed numeri- cally. The whole subject of these various measurements is exhaustively dis- cussed in a subsequent chapter on Flour-Testing, but as in this section a number of analyses are quoted, in which estimations of colour, etc., are inserted, a brief mention is here made of the principle of the method by Avhich these have been judged. 476. Colour. — Every miller and baker will be acquainted with the ordinary method, devised by Pekar, of determining the colour of a sample of flour by compressing a small quantity into a thin cake or slab, which is wetted and allowed to dry. The depth and character of the colour are then observed. This test has been in use for some time, and answers admir- ably the purpose of comparing the relative colour of two or more samples. In some of the earher tests here quoted, one of the authors employed graduated scales of colour prepared by himself ; the one of a yellow tint, for com- parison with high-class flours ; the other grey, for estimations on flours of the lower grades. The nearer the colour approaches white, the less the number assigned to it on the scale. Thus the Grey Scale starts with a very light tint, marked “ I,"' and finishes with a dark tint, marked “ 16."" The whole of the tints have an intensity proportional to their number ; thus No. 2 is exactly twice as dark as No. 1, while No. 8 is four times as dark as No. 2. The Yellow Scale, being intended for patent flours only, is not extended so far as the Grey Scale. It is difficult to compare the two scales with each other, because the colours are dissimilar ; but, in intensity. No. I yellow is about equal to IJ grey ; No. 10 yellow is three times as dark as 1 yellow, and about equal in intensity to 4J grey. The colours deepen in intensity by regular intervals from No. I to No. 10 yellow. In using these scales for testing purposes, it was found that in some samples the colour was intermediate in character between the two scales ; thus, some flours were grey, with just a tint of yellow ; others were very nearly like the Yellow Scale, but rather grey beside it ; these properties were indicated by the use of two letters, thus “7*5 G.y."" This means that the flour approached 7*5, on the Grey Scale, in depth of tint, but that it was rather yellower than the scale, but stiU nearer the grey than 344 COMPOSITION OF FLOUR AND MILLING PRODUCTS. 345 the yellow series of tints. On the other hand, 6 Y.g. means that the colour was matched and numbered on the Yellow Scale, but that it was somewhat grey in character. 477. Water-Absorbing Power. — The water-absorbing power of a sample of flour is one of the most important properties it possesses, and its deter- mination is of great value to both miller and baker. It not only governs the yield in bread of the sample, but also affords evidence of its other qualities. Hence, water-absorbing determinations are valuable in several respects. Although not always applied in precisely the same sense, for our present purpose. Water-absorbing power may be defined as the measure of the water-absorbing and retaining power of the fiour,or of the water absorbed by the fiour in order to produce a dough of definite consistency : it always being understood that the dough shall be eapable of yielding a well-risen and properly cooked loaf without clamminess. The water-absorbing power of the flour from any particular wheat is in practice governed by the way . in which it has been treated during milling. Thus an excess of water used in the conditioning process will reveal itself in a deficiency in the water- absorbing capacity of the flour. When in the following analyses the water-absorbing power is- quoted, the figures give the number of quarts of water per sack (280 lbs.) of flour required to produce a dough of a standard stiffness. The standard em- ployed is an arbitrary one, based on results obtained with the author’s “ viscometer ” (see Flour Testing, Chapter XXVI), and practically cor- responds in stiffness with a very slack cottage ” dough. 478. Composition of Roller Milling Products. — As milling is an art in which the wheat is ehanged into flour and offal, not by one but by many operations, it is a matter, not only of interest, but of importance, that it should be known where the constituents of the wheat go as eaeh successive step in gradual reduction is taken, and as the resulting products are gradually purified and separated into flours of different qualities and offals. One of the authors, some time ago, personally collected thirty-four samples of such products from a large roller mill, of which he made fairly complete analyses. The subjoined table gives the moisture, soluble extract, soluble proteins, wet and dry gluten, fat, cellulose, ash, and phosphoric acid of each sample, and also the colour of the flours, according to the scale, already described. The wheat mixture in use was composed of three parts Winter Ameri- can, one part Spring American, and two parts of Californian ; it weighed 64 lbs. per bushel. Each “ break ” or step in the reduetion of the grain results in the pro- duction of “ tailings,” which are the largest particles remaining ; semolina, consisting of smaller partieles ; and flour. The tailings of the one break constitute the feed of the next. 479. Tailings. — Studying first the tailings from each break, the moisture contained is somewhat less than that of the wheat ; this is doubtless the result of the heat evolved during the milling. The soluble extraet, soluble proteins, ash, phosphoric acid, fat, and cellulose gradually increase ; this follows from the fact that more and more of the endosperm is being removed at each break, the tailings being gradually reduced to simple bran. The gluten at first somewhat increases ; this is due to the semolina and flour of the earlier breaks being made chiefly from the heart of the grain. The portion of endosperm nearest the bran contains the most gluten, and so that eonstituent rises, until at the fifth break there is a slight fall ; but from the tailings of the sixth and seventh break no gluten is recoverable. COMPOSITION OF ROLLER MILLING PRODUCTS. 346 THE TECHNOLOGY OF BREAD-MAKING. d c/2 CO O COTtHOOfMOOOO oi oq CO 00 1 ' O I-H lOT^HCNCNlr-COCOiO r-- to CO (N oq ^ i cb cbi coTj^4^lblAo^cb cb r^\ bq I-H I-H o r-H o 1 1 1 1 1 il 1 1 1 1 1 1 1 o ! o 1 1 1 1 1 1 1 1 1 1 1 1 1 6 1*H (M coocooooqcoocM o 00 oq oq o 00 OOOOOOOOOqCvliO CO r- 00 oq CO lo IQOOCOIOOOCNCOIO (N 0^ o cq ryl pH 1 ^ r— ( r-H r-H r-H 0^ CO i~l r-H I-H r-H , o 00 ooot^ocooqt^t^ oq 00 oq CO to o 2^ COt^t^COOCOO^lO oq o CO r-H AhC,^ 6 OOOO^r^CNO c5 6 O 6 <5 b I CO oooor-ooooco o 00 •CO CO I io COCOThC^OOt^CU cp o to J i-Hi-Hi-Hoqcbcb»Orq t-H <6 1— H 6 6 ^ i .6 Ci CO CO lO CO 00 to r;- 00 CO 'a P3 Cw (N bq bq bq bq c'q a o 02 02 oq • tH loooqoo > >1:- 00 o 3 o G^Cpr^r^O O go 1>- CO 1-H o o P CO cocbiAiAcb 02 02 10 to 12^ CO do CO CO ; fH ^ O o OOOOO <1^ 020 o o o O o o o Ot-OlOO P pio to to to CO oq to I Ir^l^coobco,®^^^ i-H 1 — 1 r— 1 i-H i-H r-H to 05 cb 00 CO r— ( r-H CM w5 .3 00 OTt^(^qlOOO(^^COO TtH TJH CO CO O TtH "§ *o 4^ CO T^COiOr-HOCNCOO 05 05 i o CD (N "o CO o p ^-( p-Hp^i-HC^G^c^bqnH 6 I-H 1— H -2 2 00 OOOOOOCO-TtHOTj^ o CO oq to CO [§ cS r— 1 -^C^(NCOC21O00CO o r^ 05. o 0^ oq 'o ai t? H i6 lo'”^ ^ to lo O cb bq cb cb o o CiCOOOOOlOOt^ o oq o oq 3 o COtO'-HCN'^COCOOO CO to CN to 05 CD (01 r-H i“H i“H 1 — H r-H i“H i— H r-H bq bq bq r-H 15 1— i r-H r-H i-H i— H i-H r-H r-H r-H I-H r— H I-H r— 1 r-H • a • o 2 « O go o nn ? -'I § H cc O fH a> w Ph a ! a • G • o o • M di 02 rrt • * '^ P (f (f CO (D , pq ’Ti o o 73 03 H 03 T2 CO ^ cO ^Z2 cO ^ cO P P P $pq gw gfq ^ ^ ;h cO cO cO O O O O O O * * * 03 Jh B ^ p 00 6 ^ ?3 O ^ X H • ^ ^ P3 cO .P o o ^ p 03 fM iD ^ a f-l S After being dusted and before going to Grader, COMPOSITION OF ROLLER MILLING PRODUCTS— Cora/tnitcrf. COMPOSITION OF FLOUR AND MILLING PRODUCTS. 347 Cellulose. tH <0 CO T^^ fo 606 0-96 (GOT^^cooqTtlcocoT^^oo ooq C^CO^ROCOT^^r;-i-H icoco 66666666G 166 GO 6 4 Colour. odd 0 10 0 Th CO 1 1 1 34G. 4- 5G. 3-6G. 5- 9G. 1 CO (X) CO (Oq 0 oq Tt^•Tt^coooqrt^oqoOT^^Tt^co 0 0 Tt^ 0 TjH tH oqcocooR:)COi-HoqrHTt—1 locooocooqcoir-or-ooco lol oq (N CO oq 10 CO C^r^lC-i-Hi-HOqr-HC0^<^00^ oq 6 0 <6 000 666666666666 6 0 C 5 0 0 0 oq GOrHGOOoqoqoqt^TiHcoi:^!^* GO CO Tt^ 00 ^ 0 Tin TtH<^OC^oqcocOpHOir^i:^r-( • < 6 6 6 01—16 66666666 CO 666 6 i ’ Ci OTt^^OOTH > > > CO 0 00 GO CO 6 8 U6 8 t‘ 9 * 9 '^ 6 ^ 8 0 0 0 ■§ fl 6 6 10 02 66 02666666 02 02 02 6 :3 P-i Ph ^ J_| ?-i 0 000 0 0 02 00 02 OOOOOR 0 02 02 02 0 ■s r- 0^ 10 OOP ORO POOOOOCO P P P 0 6 6 6 6 6 ^5 66^56666661^^815 6 1 — 1 oq oq oq ^ ;zi oqoql^Hoqoqoqoqi— 1 « 2 CO CO tH oq oqcoocoococococooqoco TtH 2 i 10 »-H GO CO 0 1— iGOOt^cocococooooqi:^ CO .2-P5 0 0 rln 6 rH 1— ( 6 r— i666i— li— Ir— li— 1661— li-H i-H «2j5 C) 4^ oq 0 0 CO CO Tt^ cc O -rl 02 S p o ^ O ^ 5P 2 ^ zn <* ■— ■ * ^ w -_i cj— I o fHo'P^nSO'IP P ^ ^c3t4_^!>2'TjP ^ 't^Oa2n4^-yo2 ... .. 52 .. go-g°sg-giS • • - g • •-§ • -TS • ;&S>a = rl® r % “ -S t& o 2 M a .S ^ rl'i r-2^ *2^ Il-l ^ * * *' ^ <12 • • a;) § Ills 3^-T3T32l3'C2'^|o°§^e'&So3® T3|^T3TiTi ^TJTS h "Ml'S fi** S'S-SSoco o ^ ^ § P S ^ P P •t— t The two t, t> refer the one to the other. 348 THE TECHNOLOGY OF BREAD-MAKING. That, in the sixth break tailings, gluten is nevertheless present is shown by the quantity which is obtained from the bran flour. 480. Break Flours. — Glancing at the break flours, that from the first break contains very little gluten, but high quantities of cellulose and ash. The first break is really a splitting break, having as its object the removal of the so-called “ crease-dirt.^’ The second and third break flour is richer in gluten, but is very low in colour. The fourth and fifth break flour is low in gluten, but much better in colour. The sixth break flour falls off in colour, but is higher in gluten. The seventh break or bran flour is high in gluten and fat, low in soluble extract, and specially so in colour. 481. Middlings and Semolinas. — The middlings from the first break contain a fair amount of gluten, but the fat and cellulose are very high. The first break middlings and flour are treated as offal, and are at this stage finally separated from the other products of reduction. The granular products of the second and third breaks are separated into “ coarse semo- lina ” and coarse middlings, the latter being the finer of the two. These consist of fragments of the endosperm mixed with small pieces of offal, composed principally of broken bran. The products of the fourth and fifth breaks are also similarly divided. The coarse semolinas from the whole four breaks then go together to a set of wind or gravity purifiers, and are separated into three products according to their density. The densest of these three is the nearly pure broken endosperm ; the middle is a mixture of endosperm and branny matter ; while the back spouts yield- only very fine branny offal. The coarse middlings from the whole four breaks are likewise similarly treated over another set of purifiers. Considering first the coarse semolinas, that from the second and third breaks is lower in gluten than that from the fourth and fifth. It is also lower in fat, but higher in cellulose. The bran fragments are found more plentifully in the second and third break semolina, while the germ finds its way into that of the fourth and fifth breaks. The coarse middlings, in each case, are richer in Hour-forming constituents, consisting of more nearly pure fragments of endosperm ; those from the latter pair of breaks being the richer of the two. The next point is the nature of the respective products of the separation effected by the gravity purifiers on the coarse semolinas. Passing reference has already been made to those bodies. The densest bodies, which consequently find their way into the front spouts, contain a good proportion of gluten, the fat and cellulose being high. The material of the middle spouts also contains a considerable quantity of flour forming compounds, but no gluten was recoverable from the yield of the back spouts. The series of purifiers treating coarse middlings yields from the front spouts purified middlings, containing very little matter foreign to flour — the gluten is high, while ash and fat are low — the cellulose is some- what high. The arrangements of the mill permitted of the taking of a sample of flour that was being made from these purified middlings only ; its analysis is given in the table. This flour is lower in gluten than the straight grade, but is better coloured than even the patent. The middle spouts give a material low in ash, but higher in cellulose, than the corre- sponding yield of the purifiers treating coarse semolinas. The back spouts product yields no gluten, but a high proportion of fat, and particularly of cellulose! 482. Flours. — The whole of the flour from the various breaks, and the reductions of the semolinas (excepting those of the first break), go to form the straight grade flour : this constitutes the whole of the marketable flour produced by the grain. The water of the straight grade flour is almost COMPOSITION OF FLOUR AND MILLING PRODUCTS. 349 identical with that of the clean wheat : the soluble extract is lower, but the soluble proteins run slightly higher. The gluten is much higher, amount- ing to 8*54 against 6*04 per cent. The ash and phosphoric acid, have decreased considerably ; falling from L53 and 0*78 to 0*22 and 0*12. The ( 3 06 0,^0 (duplicates) to 0 *252 and 0 *34. The colour is 4*5 G., being exceedingly good for a straight grade flour. This straight grade was divided into a small percentage of “ Patent,'' and a “ Households " or “ Bakers’ " flour. The patent flour contains rather less water than the straight grade ; also less gluten and fat. The cellulose of the patent flour is slightly higher than that of the straight grade. The households flour is considerably richer in gluten, but in other chemical constituents closely resembles the patent. The quantities of fat, ash, phosphoric acid, and cellulose, are in each exceedingly small, so that but little difference is , observed between any of the three flours. The cellulose of flour is in so finely divided a condition that the difference in texture of two Alter papers might make a perceptible difference in two cellulose estimations in the same sample. There is not the marked difference in quality between the patent and households flours observable sometimes : the households has, in fact, not been impoverished in order to produce a quantity of a very high-class patent flour. In colour the patent stands at 3*6 G., the straight grade at 4*5 G., and the households at 5-9 G. 483. Offals : Fine Sharps. — This material, also sometimes termed “ seconds," looks as good as what one sometimes sees sold as flour. It contains a considerable quantity of gluten, 7*0, more in fact than some of the flours : but as might be expected, the fat, ash, and cellulose are high. The soluble extract is also very high. 484. Coarse Sharps, or Thirds. — These also contain gluten, but only a very small amount, 2*64. The soluble extract and proteins are very high, so also are the fat and cellulose. 485. Rolled Sharps. — The soluble extract and proteins are even higher than in the preceding ; ash, phosphoric acid, and fat are also high. 486. Bran. — The bran presents several very interesting matters for observation : as might be expected, gluten is absent, and cellulose is very high, amounting to over 18*30 of the whole substance. The bran also yields more ash and phosphoric acid than any other portion of the grain. With regard to bran, it was thought worth while to make an additional estimation of the amount of ash actually present in the soluble extract ; the result of this analysis gave 2*61 per cent. It does not follow that if the burned ash were treated with water that a larger percentage would not be dissolved. The explanation is that the physical condition of the bran, in broad flakes, is such that, whatever soluble matter are locked up within it, they do not yield themselves to treatment with water. This is exemplified in the case of the soluble extract and proteins : compared with the rolled sharps the bran yields but 9 *33 and 1 *20 respectively, against 14*95 and 3*92 in the sharps. Another sample of the bran was treated with water for 24 hours, and then the soluble extract and proteins deter- mined — the results were 13*1 and 2*2 per cent., still being less than in the sharps. These figures afford additional proof of the fact that whatever soluble constituents the bran may possess, they do not readily yield them- selves to water as a solvent : that this is due to the physical condition is shown by the sharps, which also consist of the integument of the grain, yielding so much more soluble matter, the principal difference simply 350 THE TECHNOLOGY OF BHEAD-MAKING. being that the latter is much more finely broken. The protein matter of the bran consists largely of cerealin, with which the large cuboidal cells of the inner bran are filled. This body is actively diastatic, but is altogether devoid of gluten-like properties. 487. Fluff. — A sample of this was collected from the pockets in Smith’s purifiers ; the cellulose is higher than that of flour, to which the fluff is somewhat smilar in appearance. It contains a fair amount of gluten, and also of fat. In appearance this substance looks as though it contained a good deal of the parenchymatous cellulose of the endosperm of the grain. On consulting figure 32, page 258, it will be seen that the starch granules are held together in larger cells by walls of cellulose ; these walls most probably find their way into the fluff and stive dust. 488. The Germ. — This most interesting body differs remarkably in composition from the other parts of the grain. The percentage of con- tained water is somewhat low, but the soluble extract is remarkably high, amounting to just one third of the whole of the body as removed in the modern processes of roller milling. Of the soluble extract, 15*51 per cent, consists of proteins. There is no gluten recoverable. The ash and phos- phoric acid are high ; the fat also is much higher than in any other part of the grain,'amounting to from 12 to 15’6 per cent. The cellulose is moder- ately liigh. Detailed analyses of germ have been made from time to time ; there follow results of such analyses made respectively by Richardson, Teller, and one of the authors : — Analysis Richardson. OF Germ. Teller. Jago. Per cent. Per cent. Per cent. Per cent. Water . . . . . , — 8*75 6*80 . . 13*23 Ash — 5*45 4*65 4*94 Oil — 15*61 14*38 . . 12*03 Soluble in 80 per cent, alcohol 26*45 — — — Insoluble in water . . — 1*98 — . . Dextrin 124 Soluble in water 25*47 — — . . Maltose, 5*54 Sugar or Dextrin . . — 18*85 — — Non-reducing substance — 2*94 — — Proteins . . . . — 3*65 — — Soluble in water . . 4*44 — — — Dextrin . . . . . . — 1*44 — — Proteins . . . . . . — 3*00 — — Starch, etc., undetermined — 9*95 1*60 33*78 Cellulose . . . . , . — 1*75 . , Proteins 39’ 62 Sol. proteins 15*51 Insoluble Proteins . . — 26*60 Carbo-hydrates 32*95 Insol. proteins 13*73 100*00 100*00 100*00 Osborne and Campbell find that germ contains a nucleic acid in con- siderable quantity, and having the following composition Carbon . . Hydrogen Nitrogen Pliosphorus Oxygen . . 36*48 4*48 16*17 8*96 33*91 100-00 Tliere are also present the following proteins — leucosin, a globulin, (contains only two kinds of the sulphur of edestin) and a proteose. {Jour. Amer. Chem. Soc., 1900, 379.) As one of the objects of modern milling is to thoroughly remove tlie COMPOSITION OF FLOUR AND^.MILLING PRODUCTS. 351 germ from flour, the actual effect produced by germ, when present, is a subject of great importance. An account of some experiments on mixtures of germ and flour is given later in this chapter. 489. Analyses of Products of Roller Milling, Richardson. — Clifford Richardson, Chemist to the Department of Agriculture of the United States Government, has made a most important and exhaustive series of analyses of products of roller milling. Richardson selected samples from three mills ; the first being from Messrs. Pillsbury’s mill at Minneapolis, where a straight run of spring American wheat is used ; the second, Messrs. Herr and Cissehs mill, who employ soft winter wheat ; and the third from the mill of Messrs. Warder and Barnett, of Ohio, who use all red winter wheat. These analyses, the results of which are tabulated on pages 354, 355, 356, 357, are of such great value as to warrant their quotation, together with the remarks thereon, in full. So far as the authors are aware, these are still the most exhaustive authentic series of analyses of wheat products which have been made. 490. “ Interpretation of the Analyses. — The wheat as it enters the mill is subjected to a series of operations which removes dirt, foreign seed, the fuzz (beard) at end of the berry, and a certain portion of the outer coats, through the agency of a run of stones and brushes. The result of this operation is to lower the amount of inorganic matter or ash, and to increase or decrease the other constituents but slightly, the proteins being a few tenths of a per cent, greater in amount. The point from which a con- venient start may be made is at the first break. “ The chop from the first rolls is very marked in its difference in com- jDosition from the original wheat. It, of course, has less fibre (cellulose), and also it is seen, less ash, oil, and proteins ; in fact, it is starchy. It contains more water, owing to the fact that its comminution has allowed it to absorb the moisture from the air, and in general it will be observed that the coarser or more fibrous a specimen is, the less water it contains, while the finer material holds more. For example, the percentage of water in several portions of grain are as follows : — Per cent. Original grain . . . . . . . . . . , . . . 9*66 Ready for the break . . . . . . . . . . 8*23 Chop from first break. . . . . . , . . . . . 12*52 Fifth break . . . . . . . , . . . . . . 7*62 Bran 10*91 “ The heat caused by the friction of the process, of course, is an active agent ; as may be seen on comparing the original grain and that ready for the break. The question of the relation of the various products to humidity is, however, considered in greater detail in another portion of these remarks. The “ starchy chop from the first break is carried off to the various puri- fying and grading machines, but for the present it will be left, as it is desirable to follow the breaks to the end. “ The tailings from the first scalper, consisting of the wheat grain split open along the crease, which serve to feed the second break after the cleaning which they undergo, vary but little from the wheat which goes to the first break. There are slight differences which must be attributed to the diffi- culty of selecting and preparing for analyses samples of the product of the different breaks, the finer chop having a tendency to sift out from the lighter bran ; but they are not great enough to vitiate the conclusions. In the first break so little is done, except -to crack open the wheat and clean it for the following rolls, that only a small change should be expected. 352 THE TECHNOLOGY OF BREAD-MAKING. “ Tlie chop from the second break is more from the centre of the wheat gram. It contains less ash, fat, and proteins than any of the break pro- ducts, and includes as was shown by our preliminary investigation, the greater portion of the endosperm. “ The tailings supplying the third break already show, owing to the greater amount of chop produced on the second break, a marked increase in those constituents which are peculiar to the outer portions of the grain mat IS to say, there has been a marked increase in ash, fibre and proteins! I his increase becomes still more apparent from break to break, until the bran alone is left, which contains more ash and fibre than any other pro- duct of the wheat. The several chops increase in a like manner, the last or sixth break chop holding more proteins than the bran, and even anv ^ resulting material. This is probably due to the comminution ot the bran m the last break, and consequently, as will be seen, the middlings from this chop are richer in nitrogen than any other, although not the richest m gluten, ovdng to the proportion of bran and germ which thev contain. f followed the grain through the breaks to the bran, the products 01 the purification of the chop remain to be studied. ®l^orts or branny particles removed from the chop, or from the middmgs, by aspirators, contain 'much less fibre and ash than the bran although they are of similar origin, that is to say, from the outer coats ot the gram. The analyses point to their origin from those portions of the coat which contain less ash and fibre. The middlings are graded into five classes, and in their original cleaned state they differ chemically in the fact that from No. 1 to No. 5 there IS a regular decrease in ash, fibre, and fat, while No. 5 is richer in proteins than any other. This would be expected from our preliminary examination, which showed a decrease in bran from beginning to end, and that No. 5 was the purest endosperm. After cleaning, the same relations hold good, but owing to the removal of the branny particles there is in all cases a loss of ash constituents and fibre. Ihe effect of cleaning is more apparent in" Nos. 1 and 2 where more bran IS removed. The reduction of the middlings on smooth rolls changes the com- pdsition but slightly, and the flours which originate from this process are very similar to the middlings from which they were produced. That from the fourth reduction is richer in nitrogen, as would also be the case with the fifth, although want of a specimen prevented analysis. ‘ Tlie tailings from the middlings purifiers present the usual char- acteristics of bye products, which owe their existence to the outer part of the grain, with its high percentages of ash and fibre, and, in this case, also ot nitrogen. It is remarkable, however, that the tailings marked No. 6 contain only one-third as much ash as the others ; but this is explained by the fact that they are largely composed of endosperm. ‘ Tlie tailings from the different reductions are nearly alike in com- position, with two exceptions. Those from the fourth contain little of ash, fibre, and nitrogen. Like No. 6 of the purifier tailings they consist largely of endosperm. Those from the second reduction contain much germ, and are, therefore, richer in nitrogen than the rest. Tlie repurified middlings, as might be expected, contain much more ash, oil, and fibre, than the original, and there is also an increase in nitrogen but^ not in gluten, owing to the large amount of bran they contain. Analyses of three grades of flour as furnished to the market follow. Irom a cursory glance it might be said that the low-grade flour was the best, as it contains the most proteins, but its weakness is discovered in COMPOSITION OF FLOUR AND MILLING PRODUCTS. 353 the fact that it has only 4 per cent, of gluten. The bakers’ flour contains more ash, oil, fibre, proteins, and gluten, than the patent ; but owing to the increased amount of the first three constituents mentioned, it is pro- portionately lacking in whiteness and lightness. The two flours each have their advantageous points. “ Several other grades of flour, break flour, stone flour, and flours from the first, second, and third tailings, are all very similar, and as far as chemical analyse? is concerned, good. The preliminary examination has, however, shovTi certain defects in each. The break flour is richer in proteins and gluten than any other, and if it were pure and its physical condition were good, it would be of value. “ The roller process is distinguished for the completeness with which it removes the germ of the grain during the manufacture of flour by flattening and sifting it out. This furnishes the three bye-products which are known as first, second, and third germ. They consist of the germ of the wheat, mixed with varying proportions of branny and starchy matter, the second being the purest. They all contain much ash, oil, and nitrogen ; and if allowed to be ground with the flour, blacken it by the presence of the oil, and render it very liable to fermentation, owing to the peculiar nitrogenous bodies which it carries. “ The flour from the bran dusters is much like that from the tailings, and like the stone stock, from a chemical point of view. This merely shows that chemical evidence should not alone be taken into considera- tion, for the bran-duster flour is a dirty, lumpy bye-product, while the stone stocks are valuable middlings. Analyses of various tailings are next in the series, and need no comment. Those of the dust from middlings and dust-catchers are rather surprising, in that they both contain much gluten, and the first one much fibre ; but this is due to their containing both bran and endosperm. “ To follow the gluten through the process it is necessary to go back to the breaks. The amount in the various chops does not vary greatly. There is an apparent anomaly, however, in the fifth and sixth breaks, where no gluten was found in the feed, but much in the chop. This is owing to the fact that the feed has become at this point in the process so branny that by the usual method of washing to obtain the gluten it does not allow of its uniting in a coherent mass, and separating from the bran. “ Among the middlings, both uncleaned and clean, the fourth is the richest in gluten, and the result of the process of cleaning is to increase the amount, although slightly diminishing the nitrogen, which is due to the removal of the branny matter, which, though rich in nitrogen, is poor in gluten. “ In the products of the reduction on smooth rolls, the chops from the higher middlings are the richest, and if the analyses of the flours were complete. No. 4 would probably contain more than the lower numbers. “ The tailings are, as has been already said, remarkable, not so much that No. 1 has no gluten, but that Nos. 2, 3, 4, have 7*62 per cent., and No. 6 as much as 14*37 per cent. The regular increase shows that the highest number must contain a large portion of endosperm. “ That this is the case the microscopic examination of the different tailings has shown. No. I is found to consist almost entirely of the outer coating of the grain; Nos. 2, 3, and 4, of the same, mixed with a large proportion of endosperm, which is attached thereto, while in No. 6 it is difficult to discover any large amount of anything but flouring material, and the small percentage of ash shows also that it can not contain much bran. “ In a like manner No. 4 tailings from the reductions has 13*34 per cent, of gluten, which is owing to the large proportion of endosperm which Analyses of the Products of Roller Milling, by Richardson. 354 THE TECHNOLOGY OF BREAD-MAKING. GO CSt-OCDOOTtH'^ O? 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CO CO CO I-H CO I-H I-H CO ©1 ©1 - 4 ' CO Cl u© CO CO CO -it CO - 4 ^ k© CO 00 Cl ^ CO Cl Cl X Cl ©IkOCCClCCCOkO-HiHt'- 0 kO Cl k© k© CO ■s -X^CC (M '-H . 9 CO 9 9 HtH 9009 -l:>'';t<-r 4 H-'# 9 r-H Tf 9 CO I-H 00 00 00 G^l ©1 CO CO 1 © - 4 ^ I-H CO CO CO CO I-H i Cl (M Ol 00 00 I-H GO Hfl >©OO»©^Cll© 00 G 0 k© hH Hf ©1 1© CO i OJ - oO 9 ty I-H ’ly 0 0 k©k©©) 9 it;- 999 r;- 9 0 9 -H^ 0 CO 0 c5 "Ol <01 ^ CO I-H CO CO CO ©1 ^ ©1 00 CO I-^ CO CO 9 I-H fH I-H I-H j ’ 1 I-H r-H 1— j I-H I-H I-H I-H I-H I g ^ • ■-£ © • • s: ^2 f I I .I||| .'S •• o g ^ 2 X :=fcU. i SSt^JCOM ofc.<^-EH § § ,1 |:i H tn O O piH (/} H K CO H H Q Analyses of the Products of Roller Milling, by Richardson — Continued. COMPOSITION OF FLOUR AND MILLING PRODUCTS. 357 o voo fO (Ni Ci1 I 1 f— li-H^r-H^r-H i-HrHr— 1 i— Hr— 1 O O ^ Ci 1 1 1 _3 3 •*^ .ss lO -.09 or- 01 ^00 Lo ooot-io-^o Oi-HOOIOt- |C:tJOiipoOCO'i^O''Ht-00 CD Tt< O 05 00 05 CD O CO CD CD 05 CO < I-^COOIOICOCO^’ ‘ ’A' "i-HGOCOO OI ’ ’ ’ 9 CD * q3 eo 01COt"O^OOOOOOOOt"OOOOOCO’H^ Or-HTHt^Oi-HCOOOOOOGOOOirOi— IIOOI )0 OI 00 CD 05 ri^ 05 O CO 05 CO ^ t- to ooboobcf5t^o9i9oo^M^i-Hdbob 05 OI 9 OI do 1" CO o .2 ^ 2 d I ° “ I » 1 I ::::::::: ;2 ::: :f : | S ^ ® c3 ex bfl fH p CO §© ^ M pls> sla>| i ^ ^ ^ t ^ ^ -S S o ^ S -S ^'^Ii.So-^0^.2-^O-^*^c5c50O©£H ^ M ^ Pq 02 Eh 02 02 H pti Ph ffl O W > S m TS 0 o ^ § o “ . X g • o r§ rS M ' o qH ^ bO qq -§ -g 2 bc;§ -g © © S S § ^ ^ ^ np c3 ^ c3 c3 o vp c5 ^^fq^P^PPpH 358 THE TECHNOLOGY OF BREAD-MAKING. it'^cohtains, and in this case, too, the fact of the presence of so much of the interior of the berry is presaged by the low percentage of ash. The remaining tailings of this class have little or no gluten, with the exception of No. 1, as they contain very little endosperm. “ In connection with the remaining specimens, the gluten has been already mentioned, and the results as a whole warrant the conclusion that less of it is wasted in the bye-products than would be imagined. For a complete discussion of this point, data, which are not at hand in regard to the per cent, of each material produced, are necessary. “ The products from Virginia wheat, similar to those which have just been described, present the same but not as wide variations in the breaks and in the flours ; the low grade, instead of containing less gluten, has more than the bakers’ or patent. This may be due to the greater softness of the wheat in consequence of which it is less suited to the process, a fact which is confirmed to a certain degree by the specimens of flour from Ohio wheat, among which the low grade, although not exceeding the other brands in the amount of gluten, approaches very nearly to them, and it is there- fore only reasonable to conclude that the spring wheats are particularly suited for roller milling. “ One of the characteristic features of the roller milling process, as has been mentioned, is the removal of the germ of the grain, thus pre- venting its injuring the quality of the flour. Among the bye-products of the Pillsbury mill are included three separations of germs, known as first, second, and third. They are all rich in oil and proteins, which to- gether form one half of the substance. The second germ seems to be freer from contamination, and was selected for a more detailed examination [of which the results are given, together with those of other analyses, in a preceding paragraph]. “ It has been found that the water extract, if left in contact with the residue of the germ, would soon be the cause of a pecuhar fermentation. This shows the bad effect the presence of this soluble protein would have in flour, causing a fermentation or putrefaction which would injure and discolour it. The oil in the germ is also an additional source of trouble, in that it is readily oxidized under certain circumstances and tends to blacken the flour.” 491. Further Examination of Flours Produced during Gradual Reductions. — The great importance which attaches to these led the authors to make a further series of examinations of the flours produced at the various breaks and during the reductions of the middlings, together with the finished flours, straight grade, bakers’, and patent. For the series of samples in illustra- tion of this point, the authors have to thank an important firm of Liver- pool millers, whose mill is arranged on Simon’s system. As being of more immediate importance to the miller and baker, the tests have been confined to estimations of moisture, gluten, water-absorbing power, and colour. The wheat mixture consisted of — 2 Parts Australian. 2 ,, Californian. 1 ,, White Kurrachee. 2 ,, Canadian White. 2 ,, Chicago Spring. 2 ,, Saxonska. 1 ,, Hard Duluth. 1 ,, Polish Red. 4 ,, Oregon. 1 ,, English. 18 COMPOSITION OF FLOUR AND MILLING PRODUCTS. 359 In addition to these, samples of flour from American Spring and Winter Wheats respectively are also included. Flours Yielded by Gradual Reduction. Xo. De-criptiox. Mois- Crude Gluten. Colour. Water- Absorb- ing Power. ture. Wet. Dry. j Ratio. Quarts per Sack. Lbs. per- 100 lbs. Flour. Wheat ! 13*50 25*0 9*15 2*7 1 I.Break Flour 13*18 21*0 8*57 2*4 20. G 60 53*58 2 ( II- ) ; III. r Breaks Flour 13*40 27*0 9*80 ‘ 2*7 2.G 61 54*47 3 liv. j V. Break Flour 12*80 43*0 14*6 1 i 2*9 16G.Y. 77 68*76 4 1 I. Reduction 13*24 22*0 7*7 2*8 3 G. 60 53*58 5 j II. Reduction 12*45 25*0 9*2 2*6 7 Y. 71 63*40 6 [ 1 ly ■ 1 Reduction 13*52 26*0 9*3 2*7 2 Y. 66 58*94 7 1 1 y 1 Reduction 13*04 29*0 10*1 2*8 10 Y. 70 62*51 8 VI. Reduction 13*40 27*0 9*5 2*8 9 Y. 71 63*40 9 VII. Reduction 12*30 32*0 10*5 3*0 12 Y. 75 66*97 10 Straight Grade Flour 12*94 25*0 9*5 2*6 6G. 67 59*83 11 Patent Flour 12*94 22*0 8*1 2.7 5 Y. 65*5 58*49 12 Bakers’ Flour 13*30 26*0 9*7 2*6 6G.y. 67 59*83 13 III. Flour 12*94 32*0 12*1 2*6 20 G. 81*5 72*78 14 Spring American: Weakest Break Flour 13*50 34*0 j 12*0 2*8 8G. 71*0 63*40 15 Strongest Break Flour 13*40 40*0 13*9 2*8 16G.Y. 72*0 64*29 16 Strong Flour from last Re- duction of Middlings 11*61 33*0 11*3 2*9 18G.Y. 98*0 87*51 17 Winter American : Weakest Break Flour 12*75 15*0 i 5*3 2*8 1*5 G. 64*0 57*15 18 Strongest Break Wheat . . 12*51 30*0 10*4 2*8 10*0 Y. 67*5 60*27 19 Strong Flour from last Re- duction of Middlings 11-30 29-0 10:2 2-8 15-0 Y. 91-0 81-26 On examining the results of these analyses, it will be seen that No. 1, the first break flour, is low in water-absorbing power ; 60 quarts:, contains about the average gluten of the series, and is low in colour. No 2 consists of the flour from the second, third, and fourth breaks ; this shows but little improvement in water-absorbing power, rather more in gluten, but a decided improvement in colour. No. 3, the fifth break flour, absorbs much more water, while the gluten is the highest of the series : this is accompanied by a considerable falling off in colour. There are next the flours produced by the' reduction of the semolinas ; that of the first reduction is low in water-absorbing power and gluten, but of good colour. The second reduc- tion produces a flour of improved water-absorbing powder and gluten, with but little variation in colour. The joint product of the third, and part of the fourth reduction, yields a flour which shows a falling off in water-absorb- ing power, with a slight increase in gluten. The remainder of the flour from the fourth reduction, together with that of the fifth, shows an increase in both water-absorbing powder and gluten, while the colour somewhat falls off. The sixth reduction flour absorbs rather more water, while the gluten is once more rather less in quantity. The flour from the seventh reduction, No. 9, shows an increase in both water-absorbing power and gluten, while 360 THE TECHNOLOGY OF BREAD-MAKING. the colour becomes slightly darker. Following these is the straight grade flour, No. 10 ; comparing this with the patent, No. 11, and bakers’ flour, No. 12, the straight grade runs intermediate between the other two in water- absorbing powder, gluten, and colour. No. 13, termed “ thirds flour,” is obtained by again rolling the tailings from the last reduction of middlings ; this flour, it will be noticed, is highest in water-absorbing power, and next to the highest in gluten, while the colour is very Ioav. Turning next to the series of flours obtained from American winter wheats, the gluten in the weakest break flour is only 5*3 per cent., while the colour is very good, and the Avater-absorbing poAA er low. The strongest break flour shows a slight increase in water-absorbing power, and a con- siderable increase in gluten : as might be expected the colour is slightly loAver. Taking next the flour from the last reduction of middlings, the Avater-absorbing poAver in this reaches the remarkably high figure of 91 quarts per sack ; the gluten, hoAvever, is absolutely less than that in the preceding ; the colour has slightly fallen off. In these three flours the moisture diminishes slightly AA'ith the increase in quantity of water absorbed. SomeAvhat similar lessons may be learned from the series of flours from American spring wheats. Again, the Aveakest break flour absorbs comparatively little water, 71 quarts, AA’hile the gluten amounts to 12*0 per cent. ; the colour is high. The strongest break flour shoAAS an increase in gluten, and a very slight increase in aa ater absorbed ; the colour has fallen off. The flour from the last reduction of middlings registers the enormous Avater-absorbing poAver of 98 quarts per sack. A dough test, AA'ith 88 quarts per sack, Avas mixed Avith the greatest difficulty, and took 257 seconds to run through the viscometer ; the 98 quarts test ran through in 64 seconds. The gluten of this flour was only 11*3 per cent., being less than in the Aveakest break flour ; the colour again descends. In this series, as in those from AA'inter AA'heats, the moisture diminishes Avith the increase of strength. 492. Damping Wheats. — It is the custom of millers to add to some of the harder and more flinty AA'heats, particularly those of India, more or less Avater as a preliminary to milling. The addition of such water is gener- ally supposed to have tAA'o effects, the first being a softening of the bran, and the second an increased yield of flour. The softening of the bran renders it less brittle, and so less gets broken up, and thus into the flour. It is essentially a question for the miller, rather than the chemist, to decide Avhether the damping of Indian AALeats renders them more AA'orkable and amenable to milling processes generally. It is quite conceivable that a “ melloAv ” AA'heat is more easily converted into flour than one AALich is hard and brittle ; but, against any consideration of ease in milling must be set the effect, if any, of damping on the after quality of the flour produced. In connection AA'ith this subject the authors have analysed a number of samples of Indian and other hard AA'heats, dry and damped, and also the flours produced therefrom. The folloAAung are the general conclusions derived from an extended and exhaustive series of experiments : — In artificially damping wheats, but a small proportion of the water finds its way into the flour. The actual amount varied from 3*8 to 17*1 per cent, of the total quantity added. This depends on the length of time allowed to elapse before grind- ing. The water penetrates evenly through hard Indian wheats in about forty-eight hours. The addition of water to wheats already containing an average quantity of water (in experiment cited, 13-2 per cent.) is decidedly deleterious ; strength and colour are both injuriously affected. But this will depend somewhat on the nature of the COMPOSITION OF FLOUR AND .MILLING PRODUCTS. 361 wheats. Thus some Indians may be damped to contain 15 per cent, of moisture, while Russian wheats should be restricted to a limit of 13 per cent. With wheats in a dry state (11-0 to 11*5 per cent, of water) damping in a slight degree does not seriously affect the colour or strength of the flour. On making baking tests with the flours from such slightly damped wheats com- pared with those of the wheats milled dry ; the damped wheat flours fall off less during fermentation, yield bread of better colour and flavour, and in practically the same quantity. The slight damping of the very dry wheats enables the miller to produce a better quality of flour. 493. Washing Wheats. — In view of the growing importance attached by millers to rigidly clean flours, and the consequent necessity for the re- moval of the dirt and other impurities often associated with wheat ; the grain, and especially the more dirty varieties, is now thoroughly washed before being milled. Although Indian and the more flinty types of wheat bear a prolonged submergence in water, the softer kinds of grain are injured by any but the shortest washing process. The modern washing machines are therefore not intended to soak wheat, but to wash it clean from extrane- ous dirt as rapidly as possible. The grain is then dried by treatment in a centrifugal machine, or “ whizzer.’^ This operation not only frees the wheat from ordinary dirt, but also largely removes bacteriological impurities which may be of an objectionable nature. The question frequently arises, what kind of water is fit for wheat wash- ing purposes ? The quantity used is large, amounting sometimes to as much as 20 gallons per bushel of grain washed per hour. Thus to wash 100 bushels of wheat hourly, in extreme cases, 2,000 gallons of water per hour may be required. The purchase of water of drinking quality for this purpose is very expensive, and may even in some places be prohibitive. Millers^are consequently compelled to seek some other source of washing water if possible. Among these, sea-water, if free from contamination, is employed, or river water is frequently used. The latter may of course be of almost any degree of purity. There is little doubt that the standard of purity for this purpose need not necessarily be so high as that required in water for drinking purposes. But taking a filtered river water which yields on analysis — Nitrogen as Free Ammonia . . . . . . 14 parts per 100,000 Nitrogen as Albuminoid Ammonia . . . . 5 ,, ,, ,, may it be used or not for wheat washing ? It need scarcely be pointed out that these data entirely condemn the water for drinking purposes. But in rapid washing as distinct from soaking, the exposure to the water is only for a very short period of time. In some experiments made, in which wheat was subjected to more prolonged treat- ment with water than occurs in the mill, it was found that the resultant flour had its moisture raised from 13*2 to 13*7 per cent., being an absorption of 0*5 per cent, of the weight of the flour. In washing, therefore, but very little water is absorbed by the grain, and of that little by far the greater part does not penetrate beyond the bran and into the flour. Corroboration of this is afforded by washing with sea-water ; the flour is not perceptibly rendered salt, and the br an is eaten and keenly relished by animals. In event of the washing water containing bacteria, there may be some appre- hension of these finding their way into the flour. But although they may possibly find a lodgment on the outer skin of the bran, in practice there is no contamination of any of the flour, except possibly the very last reduc- tions from the bran. Unwashed wheats will usually contain more bacteria than any water used for washing, and consequently are rendered bacterio- 362 THE TECHNOLOGY OF BREAD-MAKING. logically cleaner by washing with any ordinary water. Further, washing with an abundance of a slightly impure water will produce a cleaner wheat than is obtained by the use of a purer water in stinted quantity. Natur- ally the washing water should be as clean as practicable, and of a good quality ; but it is not necessary that it be judged by the same standard of purity as is required of a drinking water. Where the washing water is of the ordinary river type, a good plan is to use an abundance of this to remove the bulk of the dirt and then to give a final rinsing with a small quantity of clean water. 494. Artificial Drying of Wheats and Flours. — By means of a series of experiments on flour, Graham very clearly showed the advantages derived from gently kiln-drying excessively damp wheats. An inferior flour was taken, and one portion heated for some six hours to a temperature of 140° F. The dried and undried flours were then shaken up with water in the manner previously described for the purpose of obtaining the soluble extract, except that separate portions of the flour and water were allowed to stand for four and eight hours respectively before filtration. At the end of four hours the percentage of soluble extract, yielded by the undried flour, amounted to 10*49 per cent., while the dried sample gave only 8*7. The difference between the two at the end of eight hours was still greater ; the undried flour gave 16*11 per cent, of extract, while the dried sample yielded only 10*64 per cent. Evidently, then, this treatment, by partly destroying the diastatic power of the proteins degraded by moisture, prevents exces- sive diastasis of the starch, on the flour being treated with water. The soluble proteins, maltose, and dextrin all show a decrease, as may readily be seen on consulting the following table : — Artificial Drying OF Flour (Graham). Undried Flour, on Standing. 1 1 Dried Flour, on Standing. Maltose . . Dextrin . . i Soluble Proteins 4 hours. 6-82 0-43 3-19 8 hours. 11-14 1-23 3-74 4 hours. 4-44 1- 78 2- 48 8 hours. 4-44 2- 91 3- 29 Total Soluble Extract . . 10-44 16-11 8-70 10-64 As a result of these experiments, Graham recommended the kiln-drying of damp wheat, suggesting that the initial temperature might be 100° F., increasing slowly to 140° F., at the same time submitting it to a current of air, and taking care that the thickness on the kiln floor is not too great. {Cantor Lectures, Jour. Soc. Arts, pp. 116-7, Jan. 9, 1880.) Unfortunately, Graham seems not to have 'made any gluten determinations in these flours. The temperature he recommends (140° F. = 60° C.), is identical with that at which flour, on being heated for several hours, according to Weyl and Bischoff, appears to lose the faculty of forming gluten. {Jour. Chem. Soc., 1882, p. 537.) The authors can confirm this statement, having repeated their experiment with the same results. If the kiln-drying should destroy, or even materially impair, the gluten-forming powers of the flour, this would tend to seriously counterbalance the great benefit derived from the retarda- tion of diastasis as the result of the application of heat. The following are the results of a series of experiments on a sample of seconds flour of low quality, stone-milled from English wheats. Imme- COMPOSITION OF FLOUR AND MILLING PRODUCTS. 363 diately on receiving the sample, its strength, moisture, and colour were estimated in the usual manner. A strength determination was also made on the dough after standing 24 hours (stability test). The weather was intensely cold at the time of making these experiments ; the doughs were probably very little above the freezing point during the time they were standing. This is mentioned, because the amount of falling off in strength was so much less than that in some other samples, the results of which are recorded in the paragraph on Stability Tests in Chapter XXVI, and which were tested during a hot July. The flour was next placed above a heating furnace, and allowed to remain there for some days ; the temperature was taken from time to time, by plunging a thermometer in the flour, and was found to range between 27° and 30° C. (80*6°-86° F.). After two days’ drying a fresh series of determinations were made in the flour, and again after sixteen days. The results of the various tests are given in the follow- ing table : — Artificial Drying of Flour. Descriptio>'. Mois- ture, Crude Gluten. Colour. ! W ater-Absorbing Power. Wet. i Dry. 1 Ratio. 1 1 i Quarts per Sack. Lbs. per 100 lbs. Flour. Same after 24 hours. 'Quarts per Sack. Lbs. per 100 lbs. Flour. Undried Flour . , 1.3-4 29-0 10-3 2-8 12-0 G. 67-0 59-8 65-0 58-0 Flour after 2 days drying 10-3 31-0 10-7 2-9 12-0 G. 74-5 66-5 — — Flour after 16 days drying 6-5 32-0 11-6 2-8 12-0 G. 86-0 76-7 82-0 73-2 As might be expected, the natural result of drying is to lessen the mois- ture ; this falls in two days from 134 to 10*3 per cent. ; simultaneously the water-absorbing power rises 7*5 quarts. A diminution of moisture of 2*1 per cent, corresponds to an evaporation of 2*3 quarts per sack ; but the flour shows, as the result of actual trial, that its water-absorbing power had increased to a far greater extent. During the sixteen days the furnace was not kept continually alight, so that proportionately the moisture has not so much diminished as during the first two 'days. With a total diminu- tion of moisture of from 134 to 6*5 per cent., which equals 6*9, the water- absorbing power had increased by 19 quarts. A diminution in moisture of 6*9 per cent, is equivalent to loss by evaporation of 7*6 quarts per sack, but, as before, the water-absorbing power of the flour has increased by a much greater quantity. The next point for consideration was whether this increase in power of absorbing water might not be apparent rather than real ; and that while the flour would require more water to first convert it into dough, it would fall off to a correspondingly greater extent during fermentation. In order to obtain information on this point the 24 hours absorption tests were made ; they show that the original flour fell off during that time 2 quarts, while the dried flour lost 4 quarts in water- absorbing power. Compared with the undried flour, that which had been dried until 6*9 per cent., or 7 *6 quarts per sack of water had been evaporated, maintained, after being 24 hours in dough, the advantage in water-absorbing power to the extent of 17 quarts. In gluten the flours show a slight increase as the result of being dried. The three samples were exactly ahke in colour. These experiments confirm the baker’s view that, as a result of storing flour, its water-absorbing power materially increases -without any corre- sponding diminution in weight. It may therefore be concluded that gentle artificial drying of flour increases its water-absorbing capacity to a considerably 364 THE TECHNOLOGY OF BREAD-MAKING. greater extent than that of the water lost ly evaporation. In all prolahility, similar drying of damp wheats would have a like effect. 495. Tabulated Results of Flour Analyses. — The following tables contain analyses of flour selected from among those made by one of the authors during 1885-6. Flours were selected which are of interest for one of the following reasons — 1st, their having been produced from single wheats ; 2nd, their being well-known brands. The results may also possess some additional value as placing on record the composition of flours at the time of transition from stone to roller milling. Nos. 1-11 are the results of examination of a number of flours used in some viscometer experiments described in Chapter XXVI. The wheats in Nos. 1-4 were specially ground on stones, and the flour produced dressed through No. 9 silks. The upper gluten figures in No. 1 Avere obtained by allowing the flour to remain in dough for two hours before washing out the gluten. The flours 2, 3, 4 and 28 are marked by their very high percentage of gluten ; notwithstanding this, their absorptive capacity does not rank- so high as that of other flours whose percentage of gluten is less ; they are respectively flours from Odessa, Saxonska, Australian and Taganrog wheats. Nos. 8 and 9 are high in gluten, but still not quite so high as the group just referred to ; their water-absorbing power is, however, somewhat more. Like most of the Hungarian flours. No. 10 is high in water-absorb- ing capacity, but with only a medium quantity of gluten. The English Avheat, No. 11, flour has a high moisture content, with low gluten and water-absorbing capacity. On page 366 are given the results of analysis of a number of single wheat flours. Flours Nos. 12-16 were milled purely for the ordinary purposes of sale, as were also Nos. 19-27, and 35-36. The others were specially ground on stones as experimental tests on the respective wheats. Nos. 19-22 were milled in Glasgow, and Nos. 23-27 in Liverpool. Nos. 28-33 were all pre- pared in precisely the same manner as No. 28, hence the comparison be- tween them is very instructive. Nos. 29 and 30 show strikingly the ill effects on a flour of “ heating ’’ in the wheat ; the moisture increases, while the water-absorbing power rapidly falls off. In Nos. 14^16, and 19-22, the glutens were estimated immediately on doughing the flours : in the other analyses, unless specially stated otherwise, the doughs were first allowed to stand one hour. Among the whole of the flours examined. No. 35, from Canadian Hard Fyfe wheat, stands pre-eminent in the matter of water-absorbing power. The wheat from which this sample was made grew in Manitoba, to the north-west of Winnipeg, and was forwarded by the Canadian Pacific Railway Company. One of the authors personally visited this district in 1893, and collected samples of flour which are among those included in Chapter XXVI on Flour Testing. The results of examination of a number of well-known brands and varieties of flour are given on pages 367 and 368. The Hungarian flour. No. 37, is of the same brand as is No. 10. In the first five flours the glutens were estimated immediately, while in those following, the doughs were first allowed to stand an hour. The flours Nos. 42-44 were made from Hard Fyfe wheat. No. 79 in the preceding chapter. Nos. 39-50 are a number of well- known brands of American flour. Nos. 52-62 are various Hungarian samples ; Nos. 52-56 are different grades of flour supplied by the one mer- chant ; so are Nos. 57-59 ; and again. Nos. 60-62. No. 64 is registered as a weak flour ; it is, however, scarcely a bread flour, being used chiefly as a high-class biscuit flour. Nos. 65-67 are flours supplied by one of the largest and best known London millers. Flours used in Viscometer Experiments, Chapter XXVI. COMPOSITION OF FLOUR AND MILLING PRODUCTS. 365 CO O .S ^ O Eej c8 a> o r P.C3 O’ «2 lO i-H »o (M 05 o 05 lO CO »o Ci t;- lo 04 CO 04 CO C^l (N o cPi 4* CO lO 05 cb CO CO CO CO CO CO CO CO CO o o o lo o o o o o p p rl| o 6 GO 6 CO 00 CO ir- CO !>• !>• CO o 0^4 o "ci o p 05 p 1 1 1 I 1 1 o 1 1 1 CO JO i5 04 p 1 1 1 1 1 1 t 6 6 6 1 1 ! 1 1 1 1 Ratic f We 0 Drj 05 p (N CN 30 cb p cb 2-6 I-H CO 2-9 2-8 3-0 2-9 O 1 00 lo 00 o o o 05 (M JO p r-l I-H (N (04 I-H P p p p op Q 05 cb cb G cb cb cb p G a:) - ! 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COMPOSITION OF FLOUR AND MILLING PRODUCTS. 367 CO CO lo 05 CO 1 1 1 I 1 1 1 1 1 1 1 1 ^ 1 [ ir^ p rH p 1 1 1 1 1 1 1 1 1 1 1 1 1 1 GO 00 CO lO CO CO CO CO CO CO CO 1 1 I 1 1 1 I 1 ] f t 1 1 p p p p p 1 1 1 1 1 1 1 1 1 1 1 1 ^ 1 i4 G CO 4< !>• t- t- !>• t- o a> 3 O' I I I | 0 , 0 |d, I |o|o|o| loooop I— I •2 ^ ^ Is fl o ° (M CO (M (M QOt;-Q0 05ppQOppQOlOOOOpp c^-Hi-H(Nd5obd5Gbo so O lO CO lO 05 lO rH (N (M CO -H f-H COtHCO(MCOOOOCO CO C<1 O 5 i.2 oS cS c>otiD2 fl 2^3 0 0 0 _oj3 ^_q sh 00 3 i; .N waars slrla ir-ooc50--H c<^coTt^ocol:^ooc50l— loqcoTjHioco COCOCOtJ^tH T^^T^^''^T^^T^^TtlTt^'^lO»O^O^OlOlOlO Well-known Brands and Varieties of Flour — Continued. 868 THE TECHNOLOGY OF BREAD-MAKING. p . 0 Sj cc S . t- O'. 0 CO CO 0 0 CO CO d >H >H !>| 5 3 3 3 3 3 3 'o 0 »o 0 0 0 0 p P P P P p p 0 p p p p 0 _| i-H 00 CO <6 id id cd 00 cd 60 G G t>. G G r-l 1—4 oq i-H pH i-H r-l Cq Cl 00 t;- p p p p p p p p 9 9 p p p p t;- j.- f^'S3 1 di 1 di di CO cd cd dq dq dq cd cd G G G G G G G O) _S 00 10 CO 10 CO 0 CO 0 CO 0 10 10 3 , t;' 01 0 ^ 9 9 p p p p p p p p i> p p p 6 Cl Cl 0 Cl Cl cd 'd G dq cd 6 G 0 G G ^ G 1 ' ! ^ l-H ,— 1 ^ ,— 1 1—1 1— I pH f— 1 i-H rH 1— 1 ! poo p p 9 P P P P 9 9 p P p P P a;» 6 G ud di 6 <6 G G id G 0 G G 0 G G G G CO (M (M CO CO CO CO CO CO CO CO CO CO CO CO CO 1 I ^ t- 0 S.2 1 1 9 1 1 1 1 1 1 1 1 1 1 1 1 "3 2 1 1 ' ' 0 6 6 1 1 1 I 1 1 1 1 1 1 1 1 ^Ph ^ "o i 1 , 0 oq 0 j 2 i 9 9 9 1 1 1 1 1 1 1 1 1 1 1 1 '0 y . 1 ' ' cd 9 1 1 1 1 1 1 I 1 1 1 1 cos ■ O 54 ^ ^ ® J fl g 02 Ph c S .S ’3 ^ hfil^ • I'^l Nielli tHim-b c^^o3 M 0 O O O O CO O O O CO o Cl o CO !>• I— I (N CO '+1 t-* Ir- t- Ir- COMPOSITION OF FLOUR AND MILLING PRODUCTS. 369 Nos. 68-70 were milled at the same time as Nos. 28-33. Nos. 71-73 were obtained from Glasgow, and are representative samples of home-milled flours from American wheats. No. 74 is a sample of Pillsbury's well-known flour, imported into London by Messrs. Klein & Sons. The results of some more recent tests on flours is given in Chapter XXVI on The Commercial Testing of Wheats and Flours. 496. General Relationship existing between Water-Absorbing Power, Gluten, Moisture, and Colour of Flours. — Reviewing the whole series, the highest water-absorbing powers are not associated with highest glutens, neither are they with lowest moistures ; while the low strengths are in some instances found with low, and in others with high glutens. Compar- ing water absorption with moisture, the dryness of a flour does not necessarily correspond with its water-absorbing power, although in many instances a connection may be observed between them. With one and the same flour, increase or decrease of moisture influences the water-absorbing capacity to a very marked degree. The colour does not bear a very close relation- ship to the other properties referred to, because it is so largely governed by the methods employed in milling. With flours produced at different stages of the same milling process from one wheat or wheat mixture, the colour almost always falls off with increase in water-absorbing power and gluten. In judging the value of a flour from the analytic data given, the water-absorbing capacity may in the first place be taken as the measure of the water required by the flour to produce dough ; it also is the principal factor in determining the bread-yielding capacity of the flour. Water-absorption tests after standing, or their equivalents, as briefly referred to in another part of this work, indicate the degree which the dough will fall off during fermentation. The gluten is in the first place an approxi- mate measure of the flesh-forming constituents of the flour, and thus partly of its nutritive value. The quantity and quality of gluten will determine the capacity of the flour for retaining the water used in doughing ; and also, whether or not the loaf will be well risen and of good pile. For in- stance, although flour No. 16, Gradual Reduction Table, will greedily absorb water, yet it would not produce so well risen a loaf as No. 15 : this is partly due to its containing less gluten, but also to its gluten being of inferior quality. The dryness of the flour shows the actual percentage of solid food- stuffs which it contains ; and also, as has previously been explained, affords indications of its soundness. The colour of the flour, when wetted, is an approximate measure of the colour of the bread made therefrom ; but discrepancies between the colours of the flour and that of the bread are frequently observed, which in some instances are probably due to irregular- ities in the bread-making process. The same flour will produce bread of many shades of difference in colour, according to whether it be properly or improperly manipulated. 497. Effect of the Germ on Flour. — One of the questions which for a considerable time has occupied the attention of the milling world, is whether or not the removal of the germ affects the flour injuriously or otherwise. Among the various authorities on this point, Graham, Richardson, and others, are unanimous in expressing a strong opinion in favour of its removal. Briefly stated, the reasons that render this course advisable are that the presence of the germ discolours the flour, and also, as a result of its high percentage of fat, gives it a decided tendency to become rancid. In ad- dition, the germ exerts a marked diastatic action on the imperfectly matured starch of slightly unsound flours. On the other hand, the advocates for the retention of the germ assert that it renders the flour sweeter, and also B B 370 THE TECHNOLOGY OF BREAD-MAKING. causes the bread to have a pleasant moistness on the palate. Under any circumstances these results are not likely to be attained except by using the flour immediately it is milled ; this is frequently impossible, and even then the baker must be prepared to face all those difficulties caused by the presence of an undue quantity of active diastatic agents in the sponge and dough. Milling experiments on a large scale have been made on the germy semolina produced during gradual reduction. Such semolina, on being reduced on stones, yields a dark coloured unsatisfactory flour, which pro- duces a low quality bread. On rolling and repurifying these semolinas, the resulting flour is of good colour, and yields bread of high quality. So far, these experiments afford evidence directly in favour of the removal of the germ. An extensive series of experiments made by one of the authors, and previously published, prove most conclusively the ill effects resulting from the admixture of germ with flour. 498. Fatty Matters and Acidity of Flours. — Balland has made a series of determinations of these with the following results : — ■ Wheat germs mixed with bran from a recent milling. — .The fatty matter extracted; by ether contained about 83*34 per cent, of a fluid oil, and 16*66 per cent, of solid fatty acids. The original substance also contained other acids insoluble in ether. Flour from soft wheat, for army rations, from an old milling. — ^The fatty matters contained about 18 per cent, of a very fluid oil, and 82 per cent, of mixed fatty acids. The acidity of the flour was due to several acids, some soluble in water, alcohol, and ether, and others insoluble in water and in ether. Flour from hard wheat, for army rations, from an old milling. — .The fatty matters were composed entirely of free fatty acids, which hindered the hydration and extraction of the gluten. Balland deduces the following general conclusions : — The fatty matters of freshly milled flour consist of a very fluid oil and solid fatty acids of different melting points. In course of time the oil, which is very abundant at first, gradually diminishes and disappears, with a corresponding increase of the fatty acids, so that the ratio of oil to fatty acids is a measure of the age of the flour. The fatty acids themselves disappear in time and are not found in very old flours. The conversion of the oil into fatty acids is not limited to the flour only, it takes place also in the products isolated by ether. The acidity, which is the first indication of alteration of the flour, is not connected with the bac- terial decomposition of the gluten, but is derived directly from the fat. The gluten is not attacked until the fatty acids produced from the oil begin to disappear. The richer the flour is in oil, the more liable it is to alteration — as, for instance, flour from hard wheat. In order to have a flour which will keep well, it is advisable to select a soft wheat with a low percentage of fat. {Comptes rend., 1903, 137, 724). 499. Distribution of Gluten in Wheat. — Considerable interest attaches to the relative ^proportions of gluten in the flours produced during the dif- ferent operations of gradual reduction. Closely connected with this ques- tion is that of the distribution of gluten in the wheat grain. A number of writers on wheat make the statement that gluten is found almost, if not quite,* exclusively in the inner layer of the bran ; and that it constitutes the contents of those cuboidal cells seen so prominently in the inner layer of bran when microscopically examined. These cells are even now fre- quently termed “ gluten cells ” from this supposed property. The bran of wheat contains, however, no gluten whatever, the whole of that body being derived from the contents of the endosperm. Hence it follows that flour contains more gluten than does whole wheat meal. The following COMPOSITION OF FLOUR AND MILLING PRODUCTS. 371 methods, suggested by Randolph of Philadelphia, may be adopted in order to j^rove the presence of gluten in the endosperm of wheat. If whole wheat grains be allowed to soak in water, to which a few drops of ether have been added to prevent germination, they will in a few days become thoroughly softened, and the contents of such a grain may then be squeezed out as a white tenacious mass. Examination of the remaining bran shows the “ gluten cells ” undisturbed, closely adhering to the cortical protective layers. By now carefully washing the white extruded mass, the major part of its starch may be removed ; and upon the addition of a drop of iodine solution microscopic examination shows numerous networks of fine yellow fibrils, still holding entangled in their meshes many starch gran- ules, coloured blue by the iodine. In carefully washed specimens these sj^ongelike networks are seen to retain the outline of the central starch- filled cells, and evidently constitute the protoplasmic matrix in which the starch granules lay. Upon gently tearing such a specimen under a moderate amplification, the fibrils will be seen to become longer and thinner, in a manner possible only to viscid and tenacious substances — a class repre- sented in wheat by gluten alone. An eminently satisfactory proof of the protein nature of these central networks may be obtained by heating the specimen in the solution of acid nitrate of mercury (Millon’s reagent), when the fibrils will assume the bright pink tint characteristic of proteins under this treatment. Another most satisfactory method of studying the distribution of gluten in sections of wheat, is that of removing the starch by diastasis effected by malt infusion. If a thin section of a wheat grain be momentarily placed in water at 100° C., so as to gelatinise the starch, then transferred when cool to filtered malt infusion, and maintained from half-an-hour to an hour at a temperature of about 60° C., all the starch will be digested away, while the insoluble protein and other constituents will remain entirely unaltered. A section of wheat grain thus treated will exhibit throughout its entire central portion close-meshed gluten networks, which become slightly denser towards the cortex of the grain. The protein character of these reticuli is here, as in the first method, susceptible of micro -chemical demonstration by Millon’s reagent. A relatively very faint colouration, indicating the presence of proteins, is noticeable in the “ gluten cells,” while the gradual condensation of the gluten of the endosperm as the cortex is approached is evidenced by a vivid colouration of the fibrils. 500. Baking Characteristics of Typical Flours. — The tables on pages 372 and 373 record not only the gluten and other determinations in certain typical flours, but also contain a statement of their general baking characteristics . 501. Seasonal Variations in Flours. — Balland arrived at the following conclusions from the analysis of 2,500 samples of flour analysed in the Laboratory of the French War Department between September, 1891, and June, 1894. He finds the water to vary from 9*40 to 16*20, being at a maximum in February and a minimum in August. The lowest percentage of acid found by him was 0*013 per cent, in January, while samples ex- amined in August contained as much as 0*037. From this he draws the conclusion that flours for long storage should be made and packed in dry cold weather. The moisture present in wet glutens is found to vary from 52 to 71*3 per cent. ; that in the best flours for bread-making being about 70 as against 62 to 65 in those of medium quality. As the acidity of the flour increases the percentage of water in the wet gluten diminishes. None of these flours contained either foreign mineral matter or farinaceous substances as adulterants. {Comptes Rend., 119, 565.) Typical Flours and their Characters. 372 THE TECHNOLOGY OF BREAD-MAKING. * Typical Flours and their Characters — Continued. COMPOSITION OP FLOUR AND MILLING PRODUCTS. 373 5 .S S o O w ^ § o cS '-CJ bO ^ rj T ' I -U O S- S g ■.;3 ^ O o c 6 O ^ V o 3 o TO c 3 © Cl . o © ^ S «3 uJ S-I ^ g ® w fS . 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'-' ^ > bD ^. © 99 ^ S-i o P be © ^ P +3 9 g§ 9 j^ 9 pg. p >9 §9 09 abc> MW P P 9 -■ ■ ■ 'd 9 i 4 :, •- bC P 43 CO © p CO O O § Seg S O CO P 4 ^ 1— 1 O O ._ ^•S 11 “ “-i >?ni bc>,§©M ^'d o » = ^-““®S«-"'cS«o l.a? a-S-f &is« g ® “b ' °P»>o?J*??8“goSS - S S 2 fl ‘<- 0 - 1.5 b © p OM -a ^-■ag o s I .ill i 3 © 'T3 p O 'd o M S ^ > P £ o o pO 9 9 _ © xn P > o ©pa p Water absorbed. Quarts per Sack. 1 iO t- 76-0 74-5 71-5 1 62-0 0 CO CO 0*19 c CO 0 00 CO GO (M r-H >>§ 0 D- '-H (M CO GO 05 CO 0.3 CO 01 6 05 <35 <35 b- 6 0 I — 1 Oi 0 CO OI 00 0 0 0 •49 05 CO GO <35 CO 0 (50 1 CO 6 bi 6 <6 CO I 1 r-H +3 49 bc © 9 P .2 'p p bO P P M .1 -2 p © § a M bO P p 9 9 P o p bl o xn 374 THE TECHNOLOGY OF BREAD-MAKING. 502. Preservation of Flour by Cold. — Balland finds that flour stored for three years in a vessel maintained at a temperature ranging between — 2 and + 2° C. underwent very little change. The sample was somewhat tasteless, a result probably of moisture in the apparatus. The amount of gluten had slightly increased, as compared with a test on the new flour ; it was homogeneous, sweet, and contained 71 per cent, of water. The fatty matters and acids were present in the same quantities as in the original flour. {Comptes Rend., 1904, 139, 473.) 503 “ Strengthening ” Flours. — Balland states that certain forms of flour have been introduced into France from Russia for the purpose of improving and increasing the yield of bread from flours poor in gluten. Three such brands of flour yielded the following figures on analysis : — “ Champion.” “ Hercules.” “ Samson.” Water 9-90 10-70 11-00 Nitrogenous matters 29-48 22-11 16-43 Fatty matters 1-60 1-45 1-20 Starchy matters 58-22 64-94 70-65 Cellulose 0-20 0-25 0-27 Ash 0-60 0-55 0-45 Gluten, moist 82-80 64-50 46-40 ,, dried 29-10 22-00 16-00 Total Nitrogen 4-717 3-537 2-628 Acidity 0-073 0-065 0-065 These flours were apparently mixtures of wheat flour with gluten flour (made by the careful desiccation and grinding of gluten). The addition of such flours to an over-bolted flour will make good its deficiency in nitro- genous matters. {Comptes Rend., 131 [13], 545). It may be doubted whether any milling operation in the way of bolting can really remove the gluten from a sample of flour. There is less gluten in the flour derived from the centre of the grain than from the outer parts of the endosperm, but the difference is not very great. The central flour from a very strong wheat may contain more gluten than the outer flour from a very weak wheat. Starting with a fine flour, it seems scarcely probable that any milling process of bolting will effect a marked separa- tion of the starch from the gluten. In all probability the very weak French flours are manufactured from correspondingly weak wheats. The simplest remedy would be to add strong Russian or other wheats to the weaker wheat ; or naturally strong flour to the weaker variety. Very pos- sibly these “ strengthening flours have their raison d'etre in an import duty which renders it more economical to use these artificially prepared flours, rather than the untreated product of the wheat. CHAPTER XVIL THE BLEACHING OF FLOUR. 504. Early Investigations. — The subject of flour bleaching came first before one of the authors in a practical form in the shape of an inquiry from one of the most widely known flour merchants of Liverpool. That gentleman submitted samples of Californian and Oregon flours and pointed out that in most properties the two were identical, and yet that as a result of the Californian being a white, and the Oregon a very yellow flour, the former commanded a considerably higher price. The question asked was can the colour of the Oregon flour be removed so as to make it similar in colour as well as in other properties to Californian flour ? In consequence a number of experiments were made in order to remove the colour if pos- sible, ozone being employed for that purpose. The experiments were re- linquished because, although the flour was bleached, it also acquired an unpleasant flavour or taint, rendering it unfit for use. This occurred a number of years ago, and subsequently Frichot in 1898 recommended and patented the employment of electrically produced ozone for the purpose of bleaching flour, but for the same reason, the production of this taint, the process was not commercially successful. Attention was, however, thus directed to the possibility of removing more or less of its natural colour from flour, and this problem became the subject of much attention. 505. Sources of Colour in Flour. — The following may be taken as a classification of the nature and sources of the colouring matter present in flour. 1. Bran. — The outer envelope of the wheat grain is from a pale yellow to a reddish-brown tint, and contains large quantities of colouring matter. If finely ground bran finds its way into flour, the particles impart their own tint to the flour, and when made into bread this colour is intensified by being dissolved and permeating the whole of the substance of the bread. 2. Crmse and other Dirt. — ^Outside dirt, especially that of the crease of the grain, may be ground up into the flour, and will thus give it a sad, bluish-grey tint. 3. Colouring Matter of Endosperm. — ^In some wheats the whole endo- sperm is more or less coloured yellow. A notable instance of these is Walla Walla wheat of Oregon (before referred to), which yields a flour sometimes as yellow as a primrose. Removal of Colour. 1. Bran. — This is now removed by careful milling and purification from all small bran particles. 2. Crease Dirt. — -To get rid of this and other outside dirt, the grain is thoroughly scoured and pohshed in the dry state, or washed and dried. Further, the grains are in the first operations of milling carefully spht longi- tudinally along the crease, and the dust lodged therein got rid of before any further reduction of the broken grain into flour. Note. — Regarding the flour as consisting only of the endosperm of the grain (or, as it is sometimes called, the kernel or the berry), ground into a fine powder, the removal of bran and crease dirt is only a removal of foreign substances, and a consequent purification of the flour. 375 376 THE TECHNOLOGY OF BREAD-MAKING. 3. Colouring Matter of Endosperm. — ^This evidently stands in a different category, because it is the colour of the flour itself, and not that of any foreign matter, even from other parts of the grain. This colouring matter is somewhat unstable in character, as it dimin- ishes very noticeably on keeping flour some two or three months, and also varies considerably in different flours. 506. Nature of Bleaching Agents. — Since the suggestion of ozone other bleaching agents have been proposed and commercially used ; among those which are practicable being nitrogen peroxide, NO 2 , and chlorine. It will be noticed that these together with ozone, are all of them direct or indirect oxidising agents. The bleaching action is not necessarily one of oxidation, because flour may also be bleached by sulphur dioxide, a powerful reducing agent. I; - But among all the various bleaching agents that are now used to the practical exclusion of the others, is nitrogen peroxide, which may be evolved either by chemical means, as the action of ferrous sulphate on nitric acid, or by the passage of an electric discharge through air. While a silent electric discharge produces ozone in proportionately large quantities, a dis- ruptive or flaming discharge causes the production of nitrogen peroxide. With intermediate forms of discharge, the resultant gas will contain a mix- ture of ozone and nitrogen peroxide, one or other predominating according to the nature of the discharge. But so arranging the spark discharge as to get an effective bleach and no taint, the active, or at any rate, predomin- ating agent, is nitrogen peroxide. 507. Andrew’s Patent. — In January, ISOl, Letters Patent (No. 1,661 of 1901) were granted to John and Sydney Andrews for certain improve- ments in the conditioning of flour, which in effect consisted in treatment with nitrogen peroxide gas. The specification states that : — “ The inven- tion consists essentially in subjecting the flour to the action of a suitable gaseous oxidising agent, whereby nascent oxygen or its equivalent is pro- duced or comes in contact with the flour. A very small quantity of the oxidising agent suffices, so little indeed that the actual composition of the flour as shown by analysis is hardly perceptibly altered. The plan we prefer is to pass the flour through various conveyors whereby it is brought in contact with the gaseous oxidising agent, and the drawings we herewith append show the apparatus which from long experiments we have found to act best with air carrying a small quantity of gaseous nitric acid or per- oxide of nitrogen. We do not, however, limit ourselves to the use of nitric acid or nitrogen peroxide, as we have found that chlorine, bromine, and other gaseous compounds capable of liberating oxygen will act with more or less efficiency. . . . The difficulty, too, of generating it [ozone] in a mill where electric sparking is especially dangerous, puts it beyond the range of ordinary practice, and, therefore, in speaking of suitable oxidising agents we do not recommend it but exclude its use. . . . By the above- mentioned treatment the colour of the flour is made whiter, its baking qualities are improved, and it is attacked by mites and other organisms to a far smaller extent. No deleterious action on the flour is caused by the above-mentioned treatment.” The Patentees claimed : — “ (1) In the process of conditioning flour and the like, passing the same with full exposure through an atmosphere containing a gaseous oxide of nitrogen or chlorine or bromine oxidising agent in the gaseous or vapourised state. (2) The apparatus for the purposes described consisting of a device for impregnat- ing air with a gaseous oxidising agent, a rotating conveyor receiving the oxidising atmosphere and through which the material to be treated is passed in a regulated stream.” ... THE BLEACHING OF FLOUR. 377 508. Alsop’s Patent. — In June, 1S03, Letters Patent (No. 14,006 of 1903) were granted to J. N. Alsop for an improved process of treating flour to purify the same and increase the nutritive qualities thereof. The speci- fication states that : — “ This invention relates to a novel process of treating flour to purify the same and increase the nutritive qualities thereof, and to this end resides broadly in subjecting the flour to the action of a gaseous medium which will operate to bleach or purify the flour and cause a reduc- tion of the quantity of the carbohydrate contents, and an increase in the quantity of the protein contents thereof. The gaseous medium which I employ is atmospheric air which has been subjected to the action of an arc, or flaming discharge, of electricity. . . . I am at this time unable to explain the reason for the change, which is produced in the flour by treating it according to my process, but in lieu of such explanation, I will give the result of the chemical analysis before and after its treatment by my process. . . . Two samples of flour were submitted for analysis to a professor of chemistry in Columbian College, Washington, D.C. : — Water Before treatment. 9*84 After treatment. 10*13 Starch, etc. 74*11 62*24 Proteins, etc. 14*99 26*71 Ash 0*44 0*30 Fat 0*62 0*62 “ It will thus be seen that the flour which had been treated showed an increase of 11*72 parts of proteins, and a decrease of 0*14 parts of ash, and of 11*87 parts of starch. ... As an incidental result of treating the flour by my process it is as above stated, highly purifled and whitened."’ Based on this description were claims for : — “ (1) The process of treating flour which consists in subjecting the same to the action of air which has previ- ously been subjected to the action of an arc or flame of electricity, sub- stantially as described. ... (6) The process of treating flour, which con- sists in subjecting it to the action of a gaseous medium capable of bleaching the flour and of simultaneously producing a decrease in the quantity of the carbohydrate contents, and an increase in the quantity of the protein con- tents thereof, substantially as described.” Subsequent investigation showed that the patentee was mistaken in supposing that his treatment increased the protein content of the flour, and accordingly in December, 1906, the Comptroller General of the Patent Offlce allowed the specification to be amended by cancelling those claims which claimed the increase of proteins as a part of the invention (of which No. 6 above is an example). The patent then became one for the subjec- tion of flour to air treated electrically in the manner described, and without any specific claim to bleaching action. 509. Author’s Investigation. — The treatment of flour by Andrew’s Patent was investigated by one of the authors and the results published in 1903. Altogether seventeen samples of flour were taken personally, of which the following is a description : — No. Description. I. Patent from Walla Wheat. Untreated. II- 5 , ,, ,, ,, ^ Once treated in model machine. 5 , ,, „ ^ Thrice „ ,, ,, ,, ^ This was treatment in a small model machine to the extent considered by the patentees as representing a full commercial bleach. ^ This was treatment to fully three times the extent of that in the preceding test, and is far in excess of any possible commercial treatment. 378 THE TECHNOLOGY OF BREAD-MAKING. No. Description, continued. ' IV. Spring American Patent. Untreated. V. „ „ ,, Once treated in model machine. VI. „ „ „ Thrice „ VII. Winter American Patent. Untreated. VIII. ,, ,, ,, 'Once treated in model machine. IX. ,, ,, ,, Thrice ,, ,, ,, ,, X. Kansas Patent. Untreated. XI. ,, ,, Once treated in model machine. XII. Low Grade from Walla Wheat. Untreated. XIII. ,, ,, ,, ,, ,, Once treated in model ma^chine. XIV. Patent from Walla Wheat. Untreated. XV. ,, ,, ,, ^ Treated in mill. XVI. Low Grade from Walla Wheat. Untreated. XVII. ,, „ ,, ,, ^ Treated in mill. The following are the results of analysis : — I. II. III. IV. V. VI. Proteins soluble in Water . . 1-82 2-07 2-55 Gliadin ex Gluten . . — . — — 715 9-35 10-25 Glutenin ,, ,, — — — 5-66 3-18 1-95 Total Proteins — — — 14-63 14-60 14-75 Gluten, Wet 331 33-3 30-1 44-0 44-6 45-0 „ Dry 10-2 9-3 8-64 ! 14-84 15-11 15-58 ,, True — — — 12-81 12-53 12-20 Water Absorption . . 640 63-5 61-0 75-5 75-0 73-5 i VII. VIII. IX. X. XI. XII. Proteins soluble in Water . . 1-61 1-59 Gliadin ex Gluten . . 6-52 6-07 — — — — Glutenin ,, ,, 3-12 3-50 — — — — Total Proteins 11-25 11-16 — — — — Gluten, Wet . . . . 37-3 37-0 35-9 52-2 52-3 37-1 „ Dry .. .. 11-15 10-66 11-26 i 16-45 16-45 12-59 „ True 9-64 9-57 — — — — Water Absorption . . . . 61-0 60-5 62-0 65-0 65-5 XIII. XIV. XV. XVI. XVII. 1 Proteins soluble in Water . . 1-20 1-20 i Gliadin ex Gluten . . — 5-59 5-44 — — Glutenin ,, ,, — 2-60 2-66 — — Total Proteins — 9-39 9-30 — — Gluten,- Wet 35-5 32-6 35-0 34-8 33.8 „ Dry 11-65 10-0 11-23 11-55 11-70 ,, True — 8-19 8-10 — — Water Absorption . . 61-0 63-0 56-0 58-5 * These were samples treated on the large scale in the ordinary way of manufacture.. THE BLEACHING OF FLOUR. 379 The whole of the above results are expressed in per centages, except those of water absorption, which were determined by the viscometer and the results expressed in quarts per sack. Pekar Colour Tests, Results of : — No. I. — Characteristic Full Yellow Tint. No. II. — Colour almost entirely discharged. No. III. — Practically identical with No. II. No. IV. — Greyish Tint of Spring American Flours. No. V. — Colour very much lighter. No. VI. — Very slightly lighter than No. V. No. VII. — Usual tint of winter patents. No. VIII. — Colour almost entirely discharged. No. IX. — Practically identical with No. VIII. . No. X. — Good colour Kansas Flour. No. XI. — Colour very much lighter. No. XII. — Very dark and sad grey tint. No. XIII. — Colour improved, but still very dark. No. XIV. — Characteristic Full Yellow Tint. No. XV. — Colour almost entirely discharged. No. XVI. — Very dark colour. No. XVII. — Colour improved, but still dark. Baking Tests were made on small quantities of flour with the follovung results : — Nos. I., II. and III. — ^Very little difference in quantity of water taken or general behaviour during fermentation. Crumb of No. I. loaf full yellow colour. No. II. much whiter, difference very striking. No. III. very slightly whiter than No. II. No perceptible difference in odour or taste of Nos. I. and II. No. III. possessed the unpleasant odour of over- treatment. (See subsequent reference.) This flour was too weak to bake properly by itself by the method of testing that was employed. Nos. IV., V. and VI. — The same quantity of water was used with all three samples. No. VI. worked the best. No. V. the next, and No. IV. the last. Being a very strong flour. No. IV. was “ gluten-bound,"" but Nos. V. and VI. worked much freer, yielding a bolder and better shaped loaf. In colour. No. V. was a marked improvement on No. IV., and No. VI. was again slightly lighter. Nos. IV. and V. showed no differences in flavour or odour, but No. VI. had the same unpleasant smell of over- treatment. Nos. VII., VIII. and IX. — In these flours No. IX. took rather less water than the other two at the start, but worked better and held up better. Same improvement in colour, again slight improvement in thrice treated sample. In this case No. IX. was devoid of smell of over-treatment. Nos. X. and XI. — The latter worked slightly the better ; the improve- ment in colour was very marked, but not quite so striking as with the very yellow flours. No difference in odour or flavour. Nos. XII. and XIII. — The very low grades show an improvement in colour, but as would be expected, the bleaching cannot confer a bloom which is not present in the original flour itself. So far as the colour of the low grade is due to crease dirt, and other external dirty matter, such matter is of a description which is only slightly if at all amenable to bleaching processes. Nos. XIV. and XV. — These flours are practically the same as Nos. I. and II., except that the bleaching treatment has been carried out on the manufacturing scale in the mill, instead of in the small model machine. The results are practically identical ; and, if anything. No. XV. showed a greater improvement over No. XIV. than No. II. did over No. I. There 380 THE TECHNOLOGY OF BREAD-MAKINGo was not the slightest sign of any deterioration in odour or flavour of No. XV. compared with XIV. Nos. XVI. and XVII. are practically repetitions of Nos. XII. and XIII., except that the treatment was carried out on the manufacturing scale. Presence of Foreign Matters in the treated flour. It must first be remembered that nothing is added to the flour but minute quantities of the oxides of nitrogen, produced from nitric acid in the cold, and therefore under conditions in which the vapours of nitric acid are not likely to be formed. The following is a brief explanation of the probable theory of the process. The nitrogen of nitric acid exists in the form of an oxide consisting of two atoms of nitrogen and five atoms of oxygen, which may be rendered by the chemical formula, N2O5. By the action of the ferrous sulphate this body is reduced to N2O4 by the abstraction of an atom of oxygen. N2O4 is a ruddy coloured gas, which immediately escapes. This gas on coming in contact with flour imparts oxygen to its colouring matter, which it so oxidises to colourless products. In effecting this change the N2O4 is changed into a colourless gas, N2O2. This latter possesses the remark- able property of at once combining with the oxygen of the air, and again becoming N2O4, which in its turn oxidises more flour and is again reduced to N2O2. In theory this series of changes may go on indefinitely and thus a very small quantity of the nitrous fumes may act many times over as a carrier of oxygen from the air to the colouring matter of the flour, and so may be sufficient to bleach large quantities of flour. (It is some- times asserted that this bleaching action is one of nitration, but flour is also bleached when dipped into hydrogen peroxide, and no question in that case arises as to the action being anything but that of oxidation.) The question arises whether any nitric acid, as such, is conveyed into the flour. From d 'priori reasoning, the answer must be in the negative. The chemical reaction by which the gas is first liberated is one in which the nitrogen oxide of nitric acid (N2O5) is reduced to N2O4, and therefore it is not nitric acid which passes over at all. In the next place, as the action on the flour is one of oxidation, that on the N2O4 must be one of reduction of the N2O4 to N2O2, which is still further away from nitric acid. Conse- quently one would expect to find no nitric acid in the flour. What most probably occurs is that the main part of the action is the conveyance of oxygen only to the flour, and that most of the nitrogen oxides pass away with the air at the close of the bleaching operation. The following experiments have been made in order to investigate this particular point. A sample of No. VI. flour (three times treated Spring American Patent) was placed in a vessel and air forced continuously through the mass of flour for an hour. This air was next passed into a solution of potassium iodide and starch, in order to determine whether any oxides of nitrogen were thus taken out of the flour by the continuous current of air. The potassium iodide and starch solution remained absolutely colour- less, whereas the merest trace of nitrogen oxides will thus develop a deep blue colour. The conclusion arrived at is therefore that no free nitrous fumes are prese 7 it in the flour. Estimation of Oxides of Nitrogen. — The next step in the inquiry was to determine whether any, and if so, what quantity of lower oxides of nitro- gen were present in the flour in a fixed condition. For this purpose a modi- fication of the meta-phenylene-diamine test was devised. On the proper application of this test, the absence of these oxides of nitrogen is shown by the absence of any colouration, while their presence develops a brown tint in the liquid under examination (which in this case consisted of mixtures of flour and water). This test was applied to the following flours, with the results appended : — THE BLEACHING OF FLOUR. 381 IV. — No colouration. V. — Very slight colouration. VI. — Decided colouration. XI\^. — No colouration. XV. — Slight colouration. Similar mixtures of flour and water were next prepared, to which were added known quantities of a standard solution of lower oxides of nitrogen. These tests were continued until the colours of the solutions of the flours under examination had been matched. In this way it is possible to make an approximate estimation of the quantity of oxides of nitrogen present in the flour. The following were the results : — No. IV. — Untreated Spring American Patent. Free from lower oxides of nitrogen. No. V. — Contained about 0*0003 per cent., or 3*0 parts per million, and certainly less than 0*0004 per cent., or 4 parts per million. No. VI. — Contained about 0*0046 per cent., or 46 parts per million, and certainly less than 0*005 per cent., or 50 parts per million. No. XIV. — Untreated Walla Patent. Free. No. XV. — Ditto, mill treated, contained about 0*00085 per cent., or 8*5 parts per million, and certainly less than 0*001 per cent., or 10 parts per million. It will be seen that minute, but measurable traces of lower oxides of nitrogen are present in the treated flours. Having regard to the exceed- ingly small quantity present, and the harmless nature of these fixed nitrogen bodies generally, it is probable that the minute traces thus introduced into the flour are absolutely harmless. These fixed nitrogen bodies are probably nitrites, which substances are closely akin to nitrates, of which bodies salt- petre or nitre is a familiar example. Ageing Effect on Flour. — A study of the general changes induced in flour by this oxidising process leads one to the conclusion that in many ways the changes are very similar to those caused by ageing. The general improve- ments caused by proper treatment are very similar to those resulting from age ; while excessive treatment causes results not unlike those caused by excess of age on a flour. The authors are informed that flour treated by this oxidising process continues to improve for some time during storage. It is possible that the minute trace of oxides of nitrogen retained in the flour may continue to exert a beneficial influence. General Effect on Flour Constituents. — Neither starch nor other carbo- hydrate matter is probably altered by this treatment, but certain changes are induced in the gluten. In the soft flours. Nos. I., II. and III., and VII., VIII. and IX., the amount of gluten is diminished. In the harder flours there is not so great a difference, thus in Nos. IV., V. and VI. there is a slight increase, while Nos. X. and XI, are practically alike. The soft low grades, XII. and XIII., show a slight diminution. Rather curiously, in the mill treated samples there is a slight increase as the result of treatment. In order to investigate this point somewhat more closely, chemical deter- minations of albumin, gliadin, and glutenin were made on some of the more typical flours. In Nos. IV., V. and VI. the albumin shows an increase, so also does the gliadin, with necessarily a corresponding decrease in the glutenin. The amount of change observed is more than was expected, but the direction in which it goes is that corresponding with an improvement in the quality of the gluten for baking purposes in a very strong flour. The test as made is based on the well-known estimation of the amount of protein soluble in alcohol, but at present it cannot be said with certainty whether 382 THE TECHNOLOGY OF BREAD-MAKING. the substance thus dissolved from the treated flour is identical with that named gliadin. In the case of the very soft flours there is not the same production of gliadin. It is not safe to generalise on so few experiments, but so far as they have gone they point to a possible softening and mellowing of very hard flours, without a coresponding softening of flours which are already sufficiently soft. Effect on the Working Properties of the Flours. — Turning again to the table of results, there is in Nos. I., II. and III. a slight diminution in water- absorbing power ; the same also holds with Nos. IV., V. and VI. There is very little difference in Nos. VII., VIII. and IX., nor in Nos.-X. and XI. In the mill-treated samples, there is an increase in water- absorbing power as the result of oxidation. In making baking tests, the water-absorbing power of most flours seems to be slightly increased. With the very soft flours there is no very great difference observable in their behaviour during fermentation, which rather bears out the view that their gluten is not further softened by the process. But in the case of the hard flours, they are found to work more freely and to make a larger and bolder, and at the same time better shaped loaf. They do not show the same evidences of being “ gluten bound.'' While the resultant bread is improved in colour, there is, in the case of the normally treated flour, no perceptible alteration in either odour or flavour. The harder flours when treated make a rather moister and less harsh loaf. The following is a description of other flour-bleaching investigations in their chronological order. 510. Flour Bleiching by Electricity, Balland. — On comparison of samples of the same flour, unbleached and bleached by treatment with electrified air, Balland finds the latter to be distinctly whiter, but with a less agreeable odour and flavour. The only alterations that could be detected by analysis were those of the fatty matters and acidity. The fats became slightly rancid, less fluid and paler in colour. The yellow oil of the wheat had been oxidised and partially converted into white fatty acids, soluble in absolute alcohol. The acidity of the flour had increased from 0*0147 per cent, before treatment to 0*0196 per cent, after treatment. The examination of the gluten and experiments on the bread-making properties of the flour showed that the electrical treatment had not only bleached the flour but had also “ aged " it, with loss of flavour. {Comptes Rend., 1904, 139, 822.) No particulars are given as to the amount of bleaching employed by Balland, but it is suggested that an excess of the bleaching agent had been used. 511. Bleaching Flour, Shaw. — In view of the fact that oxides of nitrogen are the active agents in most bleaching processes, Shaw recommends the following method of examination — About 1 kilo of flour is boiled for four hours with 95 per cent, alcohol under a reflux condenser. The mixture is cooled and Altered, and the flour washed once with alcohol. The filtrate is evaporated nearly to dryness, and the residue extracted with a mixture of equal parts of alcohol and ether. This extract is filtered and evaporated to a syrup in a 4-inch porcelain dish. The sirupy mass is then caused to spread in a film over the inside of the dish, and a drop of a solution of diphenyl- amine in sulphuric acid is allowed to trail over the film. With artificially bleached flours, the drop of reagent used in this manner left a blue path, whereas no colour was perceptible in cases of unbleached flour. {Jour. Arner. Chem. Soc., 1906, 28, 687.) 512. Bleaching, Fleurent. — ^Fleurent calculates that from 15 to 40 c.c. THE BLEACHING OF FLOUR. 383 of nitrogen peroxide are required to bleach 1 kilogram of flour. No differ- ence in chemical composition can be detected between the bleached and the original flour. In his view the action is confined to the oil of the wheat, but this action is not a destruction of the colour by oxidation. The bleaching action coincides with a decrease in the iodine value of the oil, e.g. iodine values — Before bleaching of .. .. .. .. 86*44, 81*70, 86*10 Became after bleaching . . . . . . . . 80*79, 65*20, 56*70 By combination with the nitrogen peroxide the film of oil covering each granule of starch becomes transparent, and enables the whiteness of the starch to show through. Bleaching by age alone, on the other hand, in- volves an oxidation of the oil and the precipitation of white, fixed, fatty acids. The action of ozone results in an increase in the iodine value, the formation of volatile acids, and the constancy of the total acidity on keeping. The following is a test for bleached flours, based on the fixation of the nitro- gen peroxide by the oil : 50 grams of flour are extracted by petroleum spirit, the extract is evaporated at a low temperature, and the oil is re- dissolved in 3 c.c. of amyl alcohol. The solution is treated in a test-tube wdth 1 c.c. of alcohol containing 10 grams of caustic potash per litre. With normal flours there is no change in colouration, but with bleached flours the colour changes to orange-red, proportioned in intensity to the quantity of nitrogen fixed. The test will reveal the presence of 5 per cent, of bleached flour in a sample. Bleaching has no action on the enzymes of the flour, but the oil shows less tendency to become rancid on keeping in proportion to the quantity of nitrogen peroxide fixed. In this sense the keeping properties of the flour are enchanced by bleaching. {Comptes Rend., 1906, 142, 180.) It will be seen that Fleurent is of oj^inion that bleaching is an act of nitration rather than of oxidation. 513. Injurious Effects of the Bleaching of Flour, Ladd. — In Bulletin No. 72 issued by the Experiment Station of North Dakota, U.S.A., and published by the U.S. Government, and also in a paper read by Ladd before the Convention of Food Commissioners at Jamestown, a very positive stand is taken against the practice of bleaching, which is denounced as unessen- tial, undesirable, dangerous, and a fraud. Ladd enunciates the principle that “ the addition of any unnecessary chemicals to a food or beverage shall not be deemed as justifiable or law'ful in any product until it has been clearly and satisfactorily proven that the chemical or drug as found in the food, should it there remain, is entirely harmless, that it does not injure or in any w’ay lessen the food value, and that fraud in its use is not thereby abetted. Thus the burden of proof falls as it should upon those w4io w'ould add foreign and unessential chemicals of whatsoever kind to any article of food or beverage intended for the general consumption of the people at large, and not upon those whose duty it is to see that the law's are enforced.” Ladd contends that an injurious substance in the form of nitrites is left in the flour. He further finds that oil from w'ell-bleached flours, on being stored for several months, had a peculiar pungent rancid odour, and w'as stringy and glue-like, whereas oil from a similar unbleached flour w^as whole- some and not rancid. Ladd also expresses the opinion that the bleaching of the flour has a marked injurious effect upon the gluten, and quotes some experiments to show that from flour over-bleached to a marked degree, he w^as unable to obtain as much gluten as from the same flour unbleached. On testing the water-absorbing capacity of flours, Ladd finds that the same flour when unbleached absorbed 69*5 per cent., when bleached 64 per cent., and w4ien over-bleached 60 per cent. The following is a summary of the more important of his general conclusions : — 384 THE TECHNOLOGY OF BREAD-MAKING. 1. No one lias a right to treat a product like flour, which forms the basis- of our food products, by a chemical process unknown to the consuming public. 2. Bleaching is not an improved milling process, but is the introduction of chemical agents for the purpose of treating the flour, which is analogous to bleaching of fruit and other food products. 3. There is employed in this process of bleaching a chemical agent physiologically very active. 6. Nitrous anydride, or the salts resulting therefrom, remains in the flour after bleaching. 7. The quality of gluten is injured by bleaching. 9. Bleaching permits of using low grade flours. [Bulletin No. 72, Experi- mental Station of N. Dakota, U.S.A.) 514. Bleaching of Flour, Wesener and Teller. — This article is a reply to the Bulletin No. 72 by Ladd, abstracted in the previous paragraph. The writers first examined a number of flours and other food-stuffs for nitrogen trioxide. The following are a few of their results : — « Per cent. Unbleached Spring Patent Flour . . . . . . . . 0*00001 Bleached ,, ,, ,, . . . . . . . . 0*00005 Unbleached Durum Flour . . . . . . . . . . 0*000017 Bleached ,, ,, . . . . . . . . . . 0*00002 Bread from Bleached Spring Patent . . . . . . None „ „ „ „ „ 0*0000025 Corned Beef bought in the open market . . . . . . 0*00054 Ham ,, ,, ,, . . . . . 0*0013 Rain Water . . . . . . . . . . . . . . 0*000171 The highest quantity in bread from bleached flour is that given above, which amounts to 0*025 part per million, while ham contains about five hundred times as much. The U.S. Dispensatory (pharmacopoeia) gives the maximum safe dose of sodium nitrite as 3 grains, equal 0*19 gram, which is equivalent to 0*1 gram of nitrogen trioxide. In order to consume this quantity of nitrogen trioxide by eating the bread from bleached flour, 10,000 one pound loaves would have to be eaten. At the average rate of bread consumption, an individual who commenced the day he was born, would be 55 years old before he would thus have taken a single medicinal dose of nitrogen trioxide. The writers do not find the oil or the gluten of flour to be injured by bleaching, nor is there even the slightest change in any of the other proximate principles of flour. Neither they nor any of the bakers of whom they have asked an opinion w'ere able to detect by the senses of taste or smell any difference between bread baked from bleached and un- bleached flour. The writers recognise that the public demand a very white loaf. Tiiey point out that dark flours have a higher food value, and yet sell for less in the market because of their dark colour. Among such flours they cite that of durum wheat, the colour of which is a strong yellow. By bleach- ing sucli flours, they are made more acceptable to the public, and thus the food-producing area and capacity of the country is enlarged. Flour bleach- ing does not permit the substitution of an inferior article for a superior one, but on the contrary, makes more suitable for use articles which otherwise are in a measure objectionable. They disagree entirely with Ladd's general conclusions. [American Food J ournal, Sept., 1907.) 515. Chemistry of the Bleaching of Flour, Avery. — In touching on the history of flour bleaching, Avery instances Bean’s patent, 2502, 1879, as the first to mention chlorine as a bleaching agent. Frichot’s patent 21971, 1898, discloses the use of nascent oxygen, and recommends ozone. Andrews’ THE BLEACHING OF FLOUR. 385 patent 1661, 1901, recommends the use of nitrogen peroxide. Alsop’sU.S. patent, 759651, 1904, discloses the use of air treated by electricity. The general use of bleaching in America dates from the last named patent. A commercially bleached flour gave on comparison with the untreated the following results on analysis : — • Treated. Untreated. Water 10-88 .. 10-76 Mineral Matter . . . . . . . . . . 0-42 . . 0-42 Ether Extract . . . . . . . . . . 1-03 . . 1 -04 Nitrogen . . . . . . . . . . . . 1-82 . . 1-82 Crude Fibre 0-32 . . 0-31 The treated flour contained 0-78 part per million of nitrite, calculated as sodium nitrite. Reducing Efficiency of Various Agents : — Carefully 'purified oxygen. — ^No bleaching effect. The bleaching effect ascribed to oxygen is to be attributed to traces of chlorine, usually present if not most carefully purified. Ozone does not bleach flour. Electrically prepared ozone contains nitrogen peroxide, by which the bleaching is effected. Carbon dioxide is without effect on the colour of flour. Bromine bleaches effectively ; 4 c.c. of bromine vapour mixed with 3 litres of air will bleach a kilo of flour. Excess causes the flour to darken. Chlorine behaves similarly to bromine. Sulphur dioxide bleaches very slowly "and requires a large excess. Its odour is very pronounced in flour bleached by its use. Nitrogen peroxide bleaches in proportion to weight used a far greater quantity of flour than any of the other reagents. If 3 c.c. of nitric oxide gas be taken to 3 litres of air, it will efficiently bleach a kilo of flour. The maximum bleaching effect is obtained by 40 c.c. Excess injures the colour of the flour. {Jour. Amer. Chem. Soc., 1907, 571.) This paper is interesting as giving particulars of the bleaching effect of a number of bodies the use of which has been proposed for the treatment of flour. 516. Detection of Bleached Flour, Alway and Gortner. — Ahvay and Gortner have devoted considerable attention to this problem, and And that the changes produced in flour by bleaching with nitrogen peroxide are three in number, viz. : — • 1. The addition of a small amount of nitrates. 2. The addition of a small amount of nitrites. 3. The change of the colouring matter of the fat or the change in the fat itself. Fleurent proposes a test based on the change in the fat, but the writers were unable to distinguish bleached from unbleached flours by this test. Shaw’s test, described in paragraph 511, was found to be tedious and unreliable. Griess-Ilosvay Test. — ^This was a test for nitrites, devised originally by Griess, and improved by Ilosvay. The test is so delicate that one part of nitrous anhydride, N2O3, in a thousand millions parts of water may be detected by its means. The Griess-Ilosvay Reagent is prepared in the following manner : For solution No. I., 0-5 gram of sulphanilic acid is dissolved by heat in 150 c.c. of dilute (20 per cent.) acetic acid. Solution No. II., 0-1 gram of a-naphthyl- amine is heated with 20 c.c. of strong acetic acid, the colourless solution is poured off and mixed with 130 c.c. of dilute acetic acid. The two solu- tions are kept separate, and when required for use are mixed in equal pro- 386 THE TECHNOLOGY OF BREAD-MAKING. portions. The mixture is not affected by light, but should be protected from the air. This reagent produces a more or less intense pink colouration in the presence of nitrous acid and nitrites. Mode of Testing . — 'The writers found no unbleached flour to respond to this test when made with the necessary safeguards ; but they regard the precautions necessary as being extraordinary. The nitrous acid present in the air of laboratories is sufficient to give a pink colouration with un- bleached flours. The following method of working is therefore recom- mended. A laboratory table should be fitted up in the open air. The water to be used must be tested by the Griess-Ilosvay reagent in order to ensure the absence of nitrites. All apparatus, and especially the filter papers placed in funnels, are to be washed with nitrite-free water, and in the case of the latter until the washings give no reaction when tested for nitrites. Twenty grams of the flour to be tested, and 200 c.c. of water, are to be placed in a stoppered bottle and shaken at intervals for half-an-hour. The mixture is allowed to settle, and a portion of the supernatant liquid filtered through a washed filter. Ten c.c. of this filtrate are diluted with 50 c.c. of water, 2 c.c. of the Griess-Ilosvay reagent added, and heated in a water-bath to 80° C. for 15 minutes. In the absence of a pink colouration, there are no nitrites in the flour. In the presence of a pink colour, a comparison is made in Nessler glasses with a solution of a known quantity of nitrite tested in the same way. Tested in this manner, twenty-one samples of flour from mills without bleaching plant gave no reaction for nitrites. Of samples sent as bleached flours fifty-six reacted, while two gave no reaction. These two were probably sent by mistake, as their colour gave no signs of bleaching. From experiments made the writers satisfied themselves that bleached samples of flour lying side by side with unbleached ones do not impart any nitrous fumes or nitrites to the latter. The average amount of nitrite, expressed as sodium nitrite, in all the bleached samples was 6*3 parts per million. In a graduated series of tests, nitric oxide with excess of air was added to flour in measured quantity. There was a gradual increase in whiteness up to the addition of 125 c.c. of gas to a kilogram of flour (37*5 of nitrites per million) after which larger quantities of gas produced a less white flour. With even the maximum bleaching effect, the odour of the flour remained perfectly agreeable. Action of Chlorine and Bromine . — ^The maximum bleaching effect on flour is produced by 0*7 gram of chlorine and 1 *6 gram of bromine respectively. The following test serves to detect bleaching by these reagents, with quan- tities not exceeding 0*035 gram of chlorine, and 0*08 gram of bromine re- spectively. Thirty grams of the flour are extracted with benzene and the latter evaporated. A small quantity of oil remains. A piece of copper wire is heated in a bunsen flame until it no longer colours the flame green. The hot end of the wire is dipped into the oil and again brought into the flame. If chlorine or bromine has been used as a bleaching agent, a green or blue colouration will be produced. It is evident from the above test that chlorine and bromine are largely absorbed by the oil of the flour. {Jour. Amer. Chem. Soc., 1907, 1503.) The present recognised tests for the detection of bleaching agents in flour are very fully described in this paper. 517. Bleaching and Acidity, Allway and Pinckney. — ^These chemists find, as the result of a number of tests, that commercial bleaching does not increase the acidity of flours. The injurious effects attributed to the use of nitrogen peroxide are the result not of ordinary but of over-treatment. As THE BLEACHING OF FLOUR. 387 such over-treatment at the same time unfavourably affects the colour it is not met with commercially. {Jour. Amer. Chem. Soc., 1908, 81.) 518. Flour Bleaching, Snyder. — very systematic exposition of the whole subject of flour bleaching is contained in a bulletin issued by the University of Minnesota in 1908. The writer, Snyder, regards the bleaching of flour as a natural process, and introduces his subject by a reference to — The Colouring Material of Flour. — ^The composition of the colouring matter of wheat has never been determined, because it cannot be separated in a pure state from the fat and gluten with which it is mechanically associ- ated. It is soluble in ether, and in flour analyses it forms one of the well known impurities of the “ ether extract or “ crude fat.'" When the gluten is obtained mechanically, by washing the dough, it is tinged yellow with the natural colouring matter of the flour. Avery has suggested that the colouring matter of flour is a nitrogenous compound containing an amhno radical. In Bulletin No. 85 of this station it was suggested that the colouring matter was a nitrogenous compound. Other investigators believe it is a non-nitrogenous body akin to xanthophyll and carotin, the natural yellow pigments of plants. It has certain char- acteristics of carotin as capability of being decolourised by heat, light and chemical reagents. Whatever the composition of the colouring matter of wheat may prove to be, it is not a stable compound. After flour has undergone natural bleaching various tints and shades of colour are developed, particularly of grey and light yellow. These various shades and tints may serve as an index of bread-making value, but it is not possible from the colour alone of either freshly milled or cured flour to determine bread-making value. Flours that are pure white, or tinged slightly yellow, have the highest bread-making value. A dark grey or slaty colour is usually an index of poor bread-making qualities. Flours of poor colour when milled, often develop even more undesirable tints by storage. If the flours are not well milled the branny particles become discoloured through oxidation of the cellulose and the flours then show black specks. Hence it is that only well-milled flours from sound wheat are capable of being improved by storage. Bleaching Agents. — Of the various methods proposed for the bleaching of flour practically the only one that has survived the experimental stage is the nitrogen peroxide process, in which the bleaching reagent is produced directly from the union of the nitrogen and oxygen of the air by electrical action. In the bleaching of flour the unstable yellow colouring matter is acted upon by the nitrogen peroxide, and from a study of the properties of nitrogen peroxide it would appear to be an oxidation change. As will be shown later, this change, if it be oxidation, does not extend to the other constituents of the flour as fat and gluten, inasmuch as flour bleaching as now practised leaves these and other constituents unaltered as far as chemical tests are capable of determining. As a result of the nitrogen peroxide treatment, some nitrogen trioxide reacting material is left in the flour. For convenience it is assumed to be a nitrite, but cannot be a mineral nitrite like that of potassium or sodium, as it has entirely different properties. That the material is present largely in physical form can be shown by heating bleached flour to a temperature of 95® C. The flour will then be found free from nitrite reacting material provided it has been heated out of contact with a gas flame or combustion products that yield nitrites, or the flour was made from wheat free from mineral nitrates or nitrites. Fat of Bleached and Unbleached Flour. — ^When the fat of flour is obtained 388 THE TECHNOLOGY OF BREAD-MAKING. by the official method of analysis, the colouring matter, lecithin, chlorophyll residue products and other substances are recovered as mechanical im- purities mixed with the fat. The chemist uses the term ‘‘ crude fat "" or “ ether extract because of these known impurities. Some of the impurities are nitrogenous and some are non-nitrogenous compounds. Hence any change produced by bleaching, in the colour of the fat cannot be said to denote change in the composition, when it is known that the colour is one of the impurities of the fat. In the bleaching of flour it has been suggested that a slight oxidation of the fat is one of the possible chemical changes which may occur, since nitrogen peroxide, a carrier of atmospheric oxygen, is employed. Should any appreciable oxidation of the fat take place during bleaching, the fat of the bleached flour would have different properties from that of the un- bleached flour. Any such change in the fat would necessarily affect such determinations as those of the iodine absorption number and the heat of combustion. Four typical samples of flour (two bleached and two un- bleached) were selected for the purpose of extracting the fat in quantity. The flours were dried in such a way as to prevent oxidation, and the iodine number was determined. The following results were obtained : — Iodine Absorption Number Patent flour, unbleached. No. 1 . . . . . . . . . . 102*9 Same flour, bleached, No. 2 . . . . . . . . . . 103*7 Patent flour, unbleached . . . . . . . . . . . . 101*1 Same flour, bleached . . . . . . . . . . . . 102*6 Practically no greater differences were observed between the fat of the bleached and unbleached flours than between duplicate analyses of the same sample. As far as the iodine number of the fat is concerned no appreciable difference was observed between’thosebf the bleached and unbleached flours. It has been suggested that the nitrogen peroxide chemically unites with the fat, resulting in the production of nitrogenous compounds. Should any such change occur it would affect the nitrogen content of the product, and the fat from the bleached flour should show a higher nitrogen content. A number of investigators have shown that lecithin, a nitrogenous com- pound soluble in ether, is present as an impurity in the ether extract or crude fat obtained in the analysis of flour. Hence it is, wheat fat as ordin- arily obtained contains nitrogenous compounds, rendering it exceedingly difficult if not impossible to separate from that naturally present any new nitrogenous compound that may possibly be formed during the process- of bleaching. The ether extract or crude fat of three samples of unbleached flour was obtained in quantity by extraction with one of the best grades- of commercial ether. Also the ether was purified as directed in the official method of analysis and the nitrogen content of the crude fat extracted with tlie purified ether by the official method was determined. Nitrogen Content of Fat of Unbleached Flours. Commercial Purified Saini)le. Ether. Ether. 1 0*887 0*873 2 0*919 0*901 3 .' . . 0*931 0*942 It is to be noted that approximately 0*9 per cent, of nitrogen was found present as a natural constituent of wheat fat. There was no difference in the results wliether the ordinary or the modified Kjeldahl method was used for determining tlie nitrogen content of tlie fat. In determinations (qualitative or quantitative) of the nitrogen content of the fat of bleached THE BLEACHING OF FLOUR. 389 flour, the nitrogen that is naturally present must be recognised, and the presence of nitrogenous compounds in the fat cannot be ascribed to bleach- ing. The nitrogen content of the fat of three samples of flour before and after bleaching was determined with the following results : — • Nitrogen of Fat. Bleached. Unbleached. Flour A 0-866 0-887 Flour B 0-930 0-919 Flour C 0-927 0-931 Duplicate determinations w^ere made and no greater differences in the nitrogen content of the fats from bleached and unbleached flours were found than between duplicate analyses of the same sample. The quantitative determinations of nitrogen showed the bleaching of the flour did not increase the nitrogen content of the fat. The heat of combustion of the fats was also determined in a Berthelot calorimeter and practically the same caloric value was obtained for the fat from the bleached as from the unbleached flour. The differences in the heats of combustion were no greater than in the case of duplicate determina- tions on the same sample. If any oxidation or nitration had taken place during the process of electrical bleaching, it would have manifested itself in lowering the heat of combustion. Neither the iodine number, nitrogen content, nor heat of combustion shows any change to have occurred, or that the fats from bleached and unbleached flours differ. The Qlutens of Bleached and Unbleached Flours. — Snyder finds the gluten of flour to be unchanged by the act of bleaching, except in the direction of colour. He further finds that the quantity and composition of the gliadin is unaffected by the bleaching process. It would not be possible for nitro- or nitrosyl-compounds to be formed during bleaching, because not enough nitrite or nitrate reacting materials are present to permit such reactions taking place. Furthermore nitrous and nitric acids, if present in sufficient amounts to cause a reaction, would produce yellow coloured products in accord with the well known xantho- protein reaction of Fourcroy and Vanquelin, and consequently the flour would have a yellow tint. Such a procedure would be directly opposite to bleaching, and in that event the nitrogen peroxide would act as a stain and not as a decolourising reagent. The trace of nitrogen peroxide em- ployed in the bleaching of flour cannot be regarded in any way as a dye or stain, as it does not unite chemically with either the fat or the gluten, or form a coating over the surface of the flour particles. Its action upon the colouring matter of flour is similar to the change that takes place natur- ally when flour is cured and bleached by storage. Physical Absorption of Gas by Flour. — Since analyses of the fat and gluten of bleached flour indicated that no chemical combination had taken place with the trace of nitrogen peroxide used in the bleaching mixture, experiments were undertaken to determine whether the nitrite reacting material in the bleaching gas could all be accounted for as absorbed in the flour. From these experiments Snyder arrived at the following con- clusion. The nitrite reacting material in flour appears to be in physical rather than chemical combination. When the flour is heated, the nitrite reacting material imparted by bleaching is expelled. All of the nitrite reacting material in the gas employed for bleaching can be accounted for as soluble and volatile nitrites in the flour and in the air surrounding the flour, leaving no nitrite reacting material to chemically combine with the fat or gluten. When the bleaching gas w^as brought in contact with pure sand, with which it cannot unite chemically, the same amounts of nitrites were absorbed as in the case of flour. 390 THE TECHNOLOGY OF BREAD-MAKING. Loss of Nitrites in Bread-Making . — Bread made from bleached flours containing 0*00004 per cent, nitrogen as nitrites and baked out of contact with combustion of gases gives no reaction for nitrites. Bread made from unbleached flour and baked in a gas oven in which there is direct connection between the combustion chamber and the oven shows appreciable amounts of nitrites formed from combustion of the gas. When the bread was pro- perly made and baked in an electric oven there was no reaction for nitrites from either the bleached or unbleached flours, that is provided the flour itself was free from nitrite and nitrate reacting material except that imparted by the bleaching gas. Snyder regards the nitrite of bleached flour as being more probably ammonium nitrite than that of either sodium or potassium. Influence of Bleaching of Flour upon the Digestibility of Bread . — In order to determine the influence which commercially bleached flour may exert upon the digestibility of bread a series of digestion experiments was under- taken to determine the digestibility of bread made from bleached and un- bleached flour milled from the same wheat. In all, fifteen digestion experi- ments with men were made. The ration consisted of bread and milk and the general plan of the experiments was as follows. Samples of bleached and un- bleached flours and of the wheat from which the flours were made were drawn from a large commercial mill. Digestion experiments were made with bread baked from the bleached and the unbleached flours. Some of the wheat was then milled in the experimental mill of the Minnesota Experiment Station. One-half of the flour was bleached, and digestion experiments were made with bread from this bleached and unbleached flour prepared under chemical control. The results of these five series of digestion experiments are given in the table on page 391. In one of the trials or series, the nutrients of the bread made from the unbleached flour was found to have a slightly higher digestibility than the bread made from the same flour that had been bleached, while in another series the bread from the bleached flour was somewhat more completely digested. The difference in digestibility of the nutrients of the bread made from the bleached and unbleached flours was too small to be attributed to the treatment the flour had received. The average of the two series shows the bread made from both the bleached and the unbleached flours to have the same degree of digestibility, and that the process of bleaching had no influence upon the digestibility or nutritive quality of the flour. The bread for these experiments was baked in an ordinary cook stove heated by coal, and all the products of combustion of the fuel were excluded from the baking chamber. The bread both from the bleached and unbleached flour gave no reaction for nitrites, the nitrous acid products formed during the bleaching of the flour, and present to the extent of 0 *00004 gram of nitrogen determined as nitrites per 100 grams of flour, being entirely dis- pelled during the process of baking. Digestion Experiments with Pepsin Solution . — Digestion trials were made with bleached and unbleached flours in acid pepsin solution. The flours- used contained 2*04 per cent, nitrogen. The insoluble nitrogen obtained after digestion with pepsin was found to be as follows : — Trial No. Bleached Flour. Per cent. Unbleached Flour., Per cent. 1 . . 0*392 0*378 2 .t 0*343 0*356 Average • • 0*367 0*367 It is to be noted that the differences between the duplicate trials of the; same sample are as great as between the two samples of flour tested. THE BLEACHING OF FLOUR. 391 Digestibility of Nutrients. Protein per cent. Carbo- hydrates per cent. Available I Calories. Trial I. Bread from Bleached Flour. Man 1 85-74 96-96 91-67 Man 2 84-53 97-52 90-62 i\Ian 3 84-96 97-28 90-35 Average 85-08 97-25 90-88 Trial 11. Bread from Unbleached Flour. Man 1 86-97 98-47 91-46 Man 2 87-93 98-14 90-89 .Alan 3 . . 87-63 98-28 91-35 Average 87-51 98-29 91-23 Trial III. Bread from Unbleached Flour. Alan 1 91-76 99-02 93-87 Alan 2 92-14 98-08 94-97 Alan 3 91-67 99-08 95-09 Average 91-86 98-73 94-64 Trial IV. Bread made from Bleached Flour. Alan 1 92-04 99-07 94-41 Man 2 93-24 98-89 95-49 Alan 3 93-00 98-88 95-66 Average . . 92-76 98-95 95-19 Trial V. Bread from Unbleached Flour with Nitrites. Alan 1 93-56 99-14 95-21 Man 2 93-98 99-19 95-76 Alan 3 95-96 99.18 — Average 94-50 99-17 95*43 As far as digestibility in the acid pepsin solution was concerned no difference whatever was found in the digestibility of the bleached and the unbleached flours. Are Flours Bleached with Minute Amounts of Nitrogen Peroxide Injurious to Health ? — This is a question that can well be raised, because if the bleach- ing leaves any material in the bread that is injurious to health the practice should be discontinued and condemned. The form in which the flour is consumed as food, or the flnished food product, is what should be considered in answering this question. Flour is never eaten in the raw state, but in the process of bread-making, cake-making, and indeed in aU the various ways it is prepared for food it is always subjected to the action of heat. As previously stated, when flour is warmed out of contact with combustion gases the nitrite reacting material imparted during bleaching is removed, and the bread and other articles made from the flour give no reaction for nitritciS imparted by the bleaching gas. Since the material used in the bleaching of flour is expelled in the preparation of the food, there remains no question for physiological consideration. But since breads made from 392 THE TECHNOLOGY OF BREAD-MAKING. bleached and unbleached flour give practically like amounts of nitrite react- ing material when baked in gas, gasoline or kerosene ovens, it would seem that the broader question could well be raised : is the use of gas and liquid fuels for the preparation of foods, where the food comes in direct contact with the products of combustion, injurious to health 1 This broader ques- tion lies outside the province of the chemist, and also the scope of the present work. Snyder, however, points out that when breathing the air of a room it not infrequently happens that a person inhales during a day more nitrogen trioxide than is present in a pound of bleached flour in the raw state. He further points out that various other articles of food contain nitrites in considerably greater quantity than does bleached flour. If the presence of nitrites generally in these minute traces is to be regarded as injurious to health, then the national food menu must be materially curtailed. Use of Chemicals in Preparation of Foods . — The principle of the use of chemical reagents in the manufacture and refining of foods is recognised in the rules and regulations for the enforcement of the National Food and Drugs Act. Circular No. 21, U.S. Department of Agriculture, Office of the Secretary, Regulation No. II, states : “ Substances properly used in the preparation of food products for clarifying or refining and eliminated in further process of manufacture are exempt. There is no substance or material used in the manufacture of food products that is as completely eliminated from the finished product (bread) as is the nitrogen peroxide and its products, used in the bleaching or refining of flour. In the manu- facture of sugar, sulphur in the form of sulphur dioxide gas is used for bleach- ing purposes. Lime is employed later in the process for neutralising the sulphurous and sulphuric acids formed and for producing insoluble pro- ducts which are later removed by filtration. The last traces of the sulphur, however, are not entirely removed, and careful analysis of commercial samples of granulated sugar after combustion in a calorimeter have shown •0098 per cent, of total sulphur. On a percentage basis this is nearly fifty times more than the total nitrate and nitrite products retained in flour, bleached by the use of nitrogen peroxide. Furthermore sugar is used directly as food without any of the sulphur being volatilised. Notwith- standing the presence of this trace of sulphur, granulated sugar is practi- cally pure, as it is unacted upon by the sulphur. The sulphur acts only upon the colouring matter and not upon the sugar. However, a much larger amount of it is used than of nitrogen peroxide in the bleaching of flour. With large amounts of sulphurous and sulphuric acid, chemical reaction takes place with sugar, but the little used as a bleaching reagent fails to produce such a change. In the same way the small amount of nitrogen peroxide used in flour bleaching acts upon the colouring matter of the flour without uniting with any of its constituents. A large amount of gas, however, would produce chemical changes, as would a large amount of sulphur dioxide acting upon granulated sugar. Sugar is a food consist- ing of only one nutrient. In order to refine and improve it the colouring matter is removed by bleaching. This bleaching is done Avithout affecting the composition. Flour is a food consisting of several nutrients, and the colouring material is bleached by a trace of nitrogen peroxide, without otherwise affecting the composition. Snyder concludes his paper by the statement that in bread-making tests of commercially bleached flours no difference whatever was observed between the breads produced from the bleached and tlie unbleached flours milled from the same wheats, except that the bleached flours produced a whiter bread and also shoAved a tendency to produce larger sized loaves. Bleaching of the flour did not impart any odour or taste to tlie bread or leave in it any residue. The bleaching of flour enables the miller to manufacture a more uniform THE BLEACHING OF FLOUR. 393 product and to place his flour directly on the market without necessitating its undergoing bleaching and curing in storage. No difference whatever was observed between the naturally bleached flours and those bleached by the electrical process except that the latter contained traces of nitrite react- ing materials which were expelled during bread-making. (University of Minnesota Agric. Expt. Station. Bull., No. 111). 519. Bleached Flour, U.S. Board of Food Inspection Decision. — By their decision, No. 100, the United States Board of Food Inspection has given it as their unanimous opinion that flour bleached with nitrogen peroxide is an adulterated product under the Food and Drugs Act, 1906 ; and also that no statement on the label can bring such bleached flour within the law, and that such flour cannot legally be made or sold in the District of Columbia or in the Territories, or be transported or sold in interstate com- merce. (Jour. Soc. Chem. Ind., 1909, 157). This decision has since been upheld in American law-courts of first instance. At the moment of writing, the matter is being carried to the higher courts by way of appeal. 520. Bleached Flour, Additional Test for, Weil. — Weil finds that on subjecting flours to the action of the Griess-Ilosvay reagent, there are certain unbleached flours which give a colouration with the reagent. For instance, flour from some Russian wheat gave a colouration at once ; La Plata and Kansas flours reacted after standing for 5 minutes, Swedish flour after 9 minutes, and German flour after 20 minutes. These flours, therefore, contain normally a small quantity of nitrous acid or some other substance which gives rise to the action. Weil recommends the following test for ascertaining whether a flour has been bleached. A quan- tity of the flour is placed in a closed vessel through which a current of hydro- gen sulphide is passed for an hour ; the colour of the flour thus treated is then compared with that of the original sample. Unbleached flour exhibits no difference in colour after treatment with hydrogen sulphide, but bleached flour becomes darker, acquiring the original colour it possessed before bleach- ing. (Chew,. Zeit., 1909, 33, 29.) 521. Action at Law by Flour Oxidising Co., Ltd. v, J. and R. Hutchinson. — This was an action brought in March, 1909, in the Chancery Division of the High Court of Justice, England, before Mr. Justice Warrington. The plaintiffs are the owners of Andrews’ Patent, 1661 of 1901, before referred to, paragraph 507, and the action was one for infringement of the Patent by the defendants. It was alleged by the defendants that the Patent was not useful for the purpose specified, in that the baking qualities of bread made from bleached flour were not improved, that such bread was less digestible, and that the treated flour was deteriorated by the introduction or formation therein of a toxic poisonous substance. In support of this allegation, evidence was given by Ladd, who stated that he was Professor of Chemistry in the N. Dakota Agricultural College, and Food and Drug Commissioner of the State of N. Dakota, U.S.A., and deposed as follows : The sodium nitrite in commercial samples of bleached flour varied from 1 to 15 parts per million. Deterioration in gluten was found in the majority of such samples. Germ oil contained nitrogenous ingredients. There were small amounts of other oils in the flour. The oil extracted from well-made patent flour was free from nitrogen. After treatment the oil was less absorptive of iodine, and its refractive index was changed — ^the oil when tested for nitrogen showed it had been nitrated. The nitration of the oil injured the quality of the flour. It became less digestible and contained an ingredient foreign to flour. The witness then 394 THE TECHNOLOGY OF BREAD-MAKING. gave details of experiments which were described in the Chemical News of March 5, 12 and 19, 1909, from which the following are extracts: there were several kinds of experiments made, first experiments with bleached flour to determine the amount of nitrous acid or nitrites present therein ; second, experiments to determine the amount of nitrites calculated as sodium nitrite, present in bread produced from commercially bleached flour ; third, experiments as to the effect of bleaching on digestion ; fourth, experiments as to the effect of bleaching on digestion of gluten and bread. From these experiments the following conclusions were derived : I. That nitrous and nitric acid are two of the constituents formed from the bleaching of flour with nitrogen peroxide. II. The nitrites and nitrates, or nitrite and nitrate reacting material, are among the products formed in the flour. III. That bread as baked in the home by the domestic method will contain from one- third to one-half of the nitrite reacting material found in the flour. IV. Oil properly extracted and purified from unbleached patent flour contains no nitrogen. V. Oil extracted from bleached flour and purified by the same methods gives a strong reaction for nitrogen, thus confirming the statement made by Lewkowitsch. VI. Oils from unbleached flours have an iodine absorption number of 101 or more, while the iodine absorption number for oils from bleached flours, when properly purified, will have a lower iodine number in proportion to the amount of bleaching. Vll. The difference in the iodine number and the difference in the nitrogen contents of the oils show that the bleaching agent has acted upon the fat of the flour. VIII. Flours aged for nine months showed no reduction in iodine number, while the same flour bleached and aged for the same length of time showed a reduction of 17*1 points, indicating that the artificial bleach- ing is not the same as the natural ageing of flours. IX. The proportion of nitrates in the bread increases as the nitrites decrease. X. The method of baking will determine to what extent the nitrates are changed or elimin- ated in the bread. XI. Artificial digestion experiments with pepsin solu- tions show that the gluten from unbleached flour was digested in 4 hours and 57 minutes ; while, under the same conditions, the gluten from the bleached flour was digested in 8 hours and 40 minutes. XII. The baked gluten from the bleached and unbleached flours showed similar variations but not so wide, the time of digestion being much less ; the same is true for the bread made from such flours. XIH. In pancreatic digestion the gluten digested in 3*19 hours from bleached flour, and in 2*31 hours from unbleached flour. The time of digestion in pancreatic solutions of the baked gluten and of the bread was in favour of the unbleached pro- duct. XIV. The experiments made with the keeping quality of bread made from bleached and unbleached flour demonstrated the antiseptic effect of the bleaching agent. XV. It has been demonstrated that when the diazo or like action took place, the acid acted upon the gluten of the flour, changing its composition so that nitrogen gas was given off when the flour was treated with an acid. XVI. The fact that the xanthoproteic reaction takes place demonstrates further that the bleaching agent has acted upon the gluten or the protein of the flour. There were further experiments as to the effect of bleached flour on rabbits. Alcoholic extracts of unbleached and commercially bleached flours were prepared and administered to rabbits ; and as a check, physio logical salt solutions containing alcohol, ranging from 7 to 16 per cent., were administered to other rabbits. The following is a summary of the results obtained. I. There is produced in flour, as the result of artificial bleaching, toxic bodies. H. Experiments previously reported indicate the possibility of a diazo reaction where flour has been subjected to bleach- ing, especially when the bleaching has been carried to a considerable extent. THE BLEACHING OF FLOUR. 395 III. The fact that the xanthoprotein reaction takes place demonstrates that the bleaching agent has acted upon the gluten or the protein of the flour. IV. Alcoholic extracts prepared from unbleached flour and fed to rabbits did not affect them. V. Alcoholic extracts prepared in the same manner from commercially bleached flour and fed to rabbits in the same way caused their death within a few hours. VI. Alcoholic extracts pre- pared from over-bleached flour in the same manner and fed in the same way to rabbits caused their immediate collapse and death. VII. Aqueous extracts prepared from over-bleached flours when fed to rabbits caused their immediate collapse and death. VIII. Alcohol and aqueous extracts from over-bleached flour, when neutralized with sodium bicarbonate and fed to rabbits, cause the death of the rabbits in a short time, demonstrating that it was not the acidity that produced the death of the rabbits. IX. In preparing aqueous extracts, all nitrite reacting material disappeared ; hence the death of the rabbits in this case must have been due to the presence of other toxic material than that of nitrites. Shepard agreed with Ladd’s evidence. Halliburton generally confirmed Ladd’s evidence. The ordinary white bread of to-day was more indigestible than the old-fashioned home-made bread ; the fact that nitrous acid was used seemed a probable explanation. The gluten was rendered less digestible by the treatment. The formation of diazo compounds was a possible result of the action of nitrous acid on proteins generally. That possibly accounted for the effect on rabbits observed by Ladd. Hehner had tested a number of samples that had been sent him. By treatment with nitrogen peroxide diazo bodies might be formed. The nitrite present in flour was no measure of the damage that had been done by treatment with nitrogen peroxide. The xanthoproteic reaction showed the presence of a body resulting from the action of nitric acid upon pro- teins. Proteins had an enormous molecular weight and a most complicated structure. Nitrous acid, which had a very small molecular weight, might have a tremendous effect on the large protein molecule. In digestion ex- periments on bread, he found in every case that the balance was in favour of unbleached flour. He had no knowledge of any diazo body having been discovered or searched for in bleached flour. As against the allegation of injury to flour by treatment with nitrogen peroxide, the following evidence was given. Ballantyne said that the baking qualities and colour of the flour were in all cases improved by the treatment. There was not the same tendency for the production of rancidity, and the action of the rope-producing organ- isms, B. mesentericus fuscus and vulgatus, was retarded. Flour was not tainted or harmed by reasonable treatment. As a result of experiments on the digestion of bread from bleached and unbleached flour he had found no difference between the two. Dewar deposed that he agreed with Ballantyne’ s evidence. He had made pepsin digestion experiments on washed gluten from bleached and un- bleached flour, and had observed no essential difference between the two. He had never heard of any case in which ill effects could be attributed to the use of treated flours. In the commercial use of Andrews’ process there was proof of the formation of nitrates and nitrites, and undoubtedly there was some distribution of nitrogen in other ways. The amount was so small that it was ludicrous to think there was any danger in the use of it. Willcox and Lu^ had repeated Ladd’s experiments on rabbits. Alcoholic extracts from bread and flour had been administered to rabbits. Both witnesses agreed that neither extracts from bleached nor unbleached flour had injured the rabbits in any way. 396 THE TECHNOLOGY OF BREAD-MAKING. 522. Judgment. — In giving judgment, Mr. Justice Warrington upheld the Patent, and decided that the allegation of injury had not been proved. The following remarks were made by the judge in the course of his review of the foregoing evidence : “I think ... on the whole of the evidence before me, that as far as baking qualities are concerned — ^that is to say, the size of the loaf, the texture of the loaf, the colour of the loaf, and the water absorption — •! am bound to hold on the whole that the Plaintiffs have estab- lished that by this process the baking qualities of the newly-ground flour are improved. . . . The Defendants have sought to establish that [in addi- tion to the introduction of sodium nitrite or its equivalent] the effect of exposing the flour to the peroxide of nitrogen is to bring about certain other deleterious chemical changes in some of the very large number of the con- stituent parts of the flour, flour being an extremely complex body. In sup- port of that theory the Defendants have called as their principal witness. Dr. L%dd, a chemist of eminence and experience in the United States, and they called him because he, as a Public Officer in the State of North Dakota, has devoted considerable attention to this question of bleaching flour, in reference to the adulteration laws of that State and of the United States. His experiments, I think, must be looked at with this qualification ; in one sense of course it renders them perhaps more valuable for this purpose ; in another sense its consideration may affect them the other way ; but I think one must bear in mind in considering these experiments, that his object was to ascertain whether the result of this treatment of the flour was or was not to render the flour an adulterated product in reference to the laws of North Dakota and of the United States, because it arose under United States law as well as under that of North Dakota. Under that law, as I understand it, a minute change in the chemical constituents of the body, and the most minute amount of antiseptic introduced into the constitution of the body, would render the product an adulterated food product within the meaning of that law. That is a consideration which one must not forget in considering these experiments. Dr. Ladd's experiments were of two kinds. They were first directed to the comparative digestibility of the flour, and of the bread made from the flour, and in his view the flour, as the result of these experiments, after treatment was digested more slowly than the corresponding flour before treatment. ... So far as even Dr. Ladd’s experiments were concerned, the difference in the time of digestion in the case of the bread made from the treated flour and the bread made from the untreated flour is so small that I think it is impossible for me to say that it establishes that, so far as digestibility is concerned, the process has a deleterions effect upon the flour. But fortunately I have not only the experiments made by Dr. Ladd, but I have experiments made by Mr. Bal- laniyne and others on the Plaintiffs’ part — I mean as to digestibility — and I have experiments made by Dr. Halliburton in England on the Defendants’ part. The result, in my opinion, of those experiments, taking them as a whole, is that, so far as the bread made from the flour is concerned, which is the important part, there is no substantial difference in point of digesti- bility between the bread made from the untreated flour and the bread made from the treated flour. . . . But the Defendants Avent further, and at- tempted to establish, not only that the digestibility of the flour was not improved, but that the flour had imparted to it certain toxic qualities Avhich made it positively injurious, and, in support of that, they relied upon the evidence of Dr. Ladd, who spoke to certain experiments performed in America on rabbits with fatal results. Those experiments were of this nature. Certain highly concentrated extracts of, first, what they called over-bleached flour, which had been purposely over-bleached for the purpose of magnifying the results — over-bleached in the sense that it was saturated THE BLEACHING OF FLOUR. 397 with oxide of nitrogen — and certain concentrated extracts of what was called commercially bleached flour, although it is difficult to say exactly what that meant, were administered to rabbits. I think each dose of those concentrated extracts administered to a rabbit contained about as much of the substance, which it was desired to administer, as would be found in 200 grams of flour, but at any rate it was very highly concentrated. The result of the administration of the extract from the over-bleached flour was that the unfortunate animals died of strong corrosive poisoning. . . . Those to which the commercially bleached flour was administered also died . . . and it would appear that they had died from some irritant poison. What it was does not appear. Those experiments, taken by themselves, were somewhat striking, but the Plaintiffs have performed experiments in Eng- land, which they were led to by the experiments spoken to by Hr. Laddy with very different results. Hr. Willcox and Hr. Luff, who are two of the most eminent men in their branch of the medical profession, have made experiments on rabbits with concentrated extracts of flour bleached under the Plaintiffs' process, and they have made these extracts, following minutely the directions given by Hr. Ladd, and they have administered them to a large number of rabbits, have kept those rabbits under observation for many days after the administration, and have observed no effect on the rabbits beyond a temporary intoxication caused by the fact that the extract was alcoholic. Now in that state of things how is it possible for me to come judicially to the conclusion — ^the onus of proof being on the Hefendants — that the bread baked from this bleached flour contains some toxic qualities which would not be contained in the bread made from the untreated flour ? It seems to me quite impossible. But I do not like to let it rest there. I think it would be extremely dangerous, from the results of the experiments made in America with the American bleached flour, bleached according to the American processes, to infer the result, which the Hefendants would ask one to infer, in reference to flour bleached by the Andrews’ process. I think that I must come to the conclusion, on the balance of the evidence, that the Plaintiffs have established that, so far as that part of the attack is concerned, no deleterious action on the flour is caused. I have not quite done with that, because I must not leave it without referring to another matter also referred to by Hr. Ladd. He said that the effect of the treat- ment, in his opinion, is that the nutritive qualities of the flour are deleteriously affected. So far as that is concerned I think that is pure theory, and I do not And any positive fact or anything which 1 can take hold of to support hat. It seems to me, therefore, that, whether you regard it from the point of view of digestion, whether you regard it from the point of view of nutri- tion, or w^iether you regard it from the point of view of positive harm, I must come to the conclusion that the Plaintiffs have established the truth of the statement in Andrews’ specification that no deleterious action on the flour is caused by the above-mentioned treatment." {Reports of Patent Cases, XXVI, 1909, 597.) The only point occurring in the judgment quoted on which perhaps comment should be made is the distinction drawn by the learned judge between American and English bleached flours. Both are bleached by nitrogen peroxide, produced in the former case under Alsop's Patent by a flaming discharge of electricity through air, and in the latter by the action of ferrous sulphate on nitric acid. Chemists in general will agree that the Alsop process is no more likely to be injurious to flour than that of Andrews. 523. Flour Bleaching, its Relation to Bread Production and Nutrition, Wesener and Teller. — This paper is very largely of the nature of a reply to Ladd, and necessarily to a great extent deals with matters already re- 398 THE TECHNOLOGY OF BREAD-MAKING. f erred to. In opposition to the view that bleaching introduces an anti- septic into the flour, experiments are quoted 1)0 show that the presence of even considerable amounts of nitrite-reacting nitrogen in flour acts favourably to the development of yeast in dough, and therefore such nitro- gen oxide is not a preservative. The writers fed rats on biscuits and bread made from bleached flour for some months, and found that they suffered no injury. They also repeated Ladd’s experiments with rabbits and found no injury was done to the animals by the extract from bleached flour. The vTiters regard it as impossible that the acid in Ladd’s flour could have done any injury to the rabbits, because of its infinitesimal amount. They calculate that the total amount of nitrous and nitric acid which might be present in one of the hours which was used by Ladd for his test, based upon double the amount of nitrite-reacting nitrogen found (3 parts per million) and all calculated to nitric acid, would be equivalent to only 5*4 milligrams (xV drop) of nitric acid. This amount of nitric acid is prac- tically (x^Vo medicinal dose of nitric acid as given in the U.S. Dispen- satory, and according to Ladd’s testimony the liquid administered to the rabbits was much greater in amount than necessary to produce the dilution specified in that work for internal doses of nitric acid. Under the circum- stances we could not expect any corrosive action from this amount of acid, even assuming that it could have been separated out of the hour as free acid without in any manner combining with the organic matter of the hour and alcohol. Diazo Test . — In view of the fact that poisonous diazo compounds are alleged to be formed by the nitrogen peroxide bleaching of flour, the vHters made the following experiment. One hundred grams of unbleached flour were introduced into a flask of about one litre capacity, and carbon dioxide passed into it for IJ hours with frequent vigorous agitation. Dilute hydro- chloric acid which had been recently boiled was added warm and the mix- ture agitated. The evolved gas was then swept by a stream of carbon dioxide into a Schiff azotometer containing the usual solution of caustic soda. A small amount of gas passed to the top which could not be absorbed by repeated agitation. The volume of this gas was 1*4 c.c. It was tested w’ith a lighted paper. It did not burn, nor did it support combustion when tested as indicated by Prof. Ladd. The above experiment, carried on in co-operation with Prof. Haines, was carried out as detailed by Ladd and used by him as testimony in North Dakota to show the presence of diazo compounds of the nature of tyrotoxicon resulting in bleached flour from the action of the bleaching gases upon the constituents of the same. The amount of gas which he obtained from the bleached flour is substantially the same as we obtained in the above experiment from unbleached flour, and is undoubtedly air which adheres to the particles of flour and which cannot be removed even by the most careful and persistent treatment with carbon dioxide. That the experiments tend to show the presence of tyro- toxicon, or that such tyrotoxicon would be formed by the action of bleaching gases on flour is not probable when we remember that this material, as found in cheese and other milk products, is wholly the result of bacterial growth, and that it is of an exceedingly unstable nature. In conclusion, Wesener and Teller emphasise their view that any improve- ment in quality brought about by removing an unusually large amount of colour present in a flour which was inferior because of the presence of such excess of colour certainly cannot be looked upon as in any way injuring or deceiving the consumer, as has been contended by some, for the cause which produced the inferiority now no longer exists. The purpose of the bleaching is to remove and not to conceal the inferiority. The prohibition of the bleaching of flour will curtail the use and cut down the price of durum THE BLEACHING OF FLOUR. 399 wheat and all wheats \\'hich have an intense yellow colour in spite of the fact that aside from this some of these wheats produce flour of the very highest quality. The effect of this is naturally felt more by the producer of wheat and the consumer of flour than by the miller whose prices are regulated by market values and competition. {Journal of Industrial and Engineering Chemistry, I., Oct., 1909.) 524. Bleaching and Flavour and Texture. — Although bleaching may materially improve the colour of a flour, it does not thereby change a lower grade flour into a higher grade one. There may be some conditioning, but the essentials of the lower grade flour still remain unchanged. Flour of the highest grade possesses a delicacy of flavour, and in the resultant bread or biscuits, a silkiness of texture, which are not present in inferior grades. Even if bleaching causes the lower grade to simulate the highest in colour, it is not simultaneously converted into flour of the flavour and texture of the highest grade. This line of argument must not, however, be pushed too far. During the whole development of milling processes, there has been a steady increase in the amount of patent flour obtainable from the wheat. At first, only a very small quantity of patent flour of the very best colour was produced. The remainder contained the rest of the flour, darkened by the presence of milling impurities. The patent flour was not only of good colour, but it vas also distinguished from the residual flour by the greater delicacy of flavour and fine texture before referred to. With improvements in milling, more of this residual flour was freed from its impurities, and obtained of equal colour to the so-called patent flour. The yield of patent flour of the standard colour was thereby increased ; but save in colour, the better puri- fication of the former residual flour did not alter the inherent qualities of the flour itself. Yet no one has regarded this transference of such flour to the patent portion as being in any way illegitimate. By parity of reasoning, an increase of the amount of flour of patent colour standard, by harmless bleaching processes, cannot be regarded as an adulteration, nor is such flour misbranded when called “ patent flour.” 525. Nutritive Value of Bleached Flours. — There are certain advocates of the general use of flour of lower grades, who have recently condemned the use of bleaching. It is difficult, however, to follow their argument. The very foundation of their position is that the darker flours are more nutritious and wholesome than those which are lighter in colour. Only, unfortunately, say they, the public is so blind to its own interests, that in the pursuit of mere whiteness it overlooks all the other solid and real advantages possessed by darker flours. But if the darker flour is unchanged in any other particular, and loses none of its food value by bleaching, then surely any process by which it is rendered more attractive to the eye should find favour with those who wish to see the naturally darker flours more widely and extensively used. Note ; Local Government Board Reports. — Two reports on the joint sub- jects of Flour Bleaching and Flour “ Improvers,” by Drs. Hamill and Monier-Williams, have just been published by the Local Government Board . A summary of their experimental results and conclusions are given in Chapter XX, paragraphs 629 and 630. CHAPTER XVIII. BREAD-MAKING. 526. Salt, Sodium Chloride, NaCl. — Havingfully^dealt with flour and yeasty there now remain only salt and water as es sential constituents of bread ; some brief reference must be made to these compounds. Salt is a white crystalline body, about equally soluble in either hot or cold water, and having a charac- teristic saline taste. Salt is used in the making of bread for two reasons — first, to give the necessary flavour, without which bread would be tasteless and insipid. In addition to its owm saline flavour, experiments have shown that the presence of salt stimulates the capacity of the palate for recognis- ing flavours of other substances. Thus, minute quantities of sugar are recognised in the presence of salt which in its absence would be unnoticed. This doubtless is one of the reasons for the importance of salt as a flavouring agent. In the second place, salt actively controls some of the chemical changes which proceed during fermentation ; thus, salt, in the quantities employed in bread-making, produces a decidedly binding effect on the gluten of the dough. It further checks diastasis, and so retards the conversion of the starch of the flour into dextrin and maltose. Salt also checks alcoholic fermentation ; the results of careful measurement of this action are given in Chapter XI., paragraph 371. The retarding influence of salt also extends to the other ferments, as lactic, viscous or ropy ferments, and so tends to prevent injurious fermentation going on in the dough. 527. Water. — In considering the quality of water for dietetic purposes,, the chemist, first and foremost, addresses himself to the task of determining whether or not the water shows evidences of previous sewage contamination. He next ascertains the hardness and also the amount of saline matters present. The methods he adopts for this purpose vary, but the conclusion at which he seeks to arrive is practically the same. It may be safely laid down as a rule for the baker that a water which would be rejected, on analysis, as unfit for drinking purposes, should also without hesitation be rejected by him. Water containing living organisms should in particular be carefully avoided, as these might very possibly set up putrefactive fermentation during panification. Among the waters which would be passed by the chemist for drinking purposes, there exist, however, considerable differences. Thus, some are hard, others are extremely soft ; salt may be present in certain waters, while in others it may be almost absent. The difference between hard and soft waters is that the former contain carbonates and sulphates of lime or magnesia in solution ; the act of boiling precipitates the carbonates as a fur on the vessel used, and so hardness due to the carbonates is termed tem- porary hardness, in distinction from that of the sulphates which, not^being removed by boiling, constitutes permanent hardness. / ]\Iuch speculation exists as to whether or not the hardness or otherwise of a water exerts any practical influence on bread-making. In brewing it is recognised that a soft water obtains more extract from the malt than a hard one, but the comparison with the case of bread is scarcely fair, because 400 BREAD-MAKING. 401 in the wort the liquid is filtered off from the “ grains/" while in bread the whole mass, whether soluble or insoluble, goes into the oven together. The general tendencies of hard water would be to dissolve less of the pro- teins than would a soft water, and consequently the dough in the former case would be, to the extent of the action of the hard water, tighter and tougher than that produced when the water is soft. (It will be remembered that gliadin is soluble in distilled water, but that the salts of the flour itself are sufficient to prevent its going into solution.) The use of very soft water is very nearly equivalent to the result produced by using softer flours. Thus, hard water will tend to make whiter bread, because, not only is the quantity of proteins dissolved smaller, but with the same quantity in solu- tion their action would be checked by the presence of the soluble lime salts. At the same time the bread would eat somewhat harsher and drier than that made with soft water. Speaking generally the changes which go on during panification proceed more rapidly with soft than with hard water. Working in a similar manner, ^.c., with the same times and temperatures, hard water is not likely to produce as good results as soft water at its best. In order to obtain the same results, the various steps in the process of fer- mentation should be somewhat modified ; thus, the bread would probably require to lie somewhat longer in the sponge and dough stages, or the tem- perature employed might be somewhat higher. Both colour and flavour of bread depend on fermentation being allowed to proceed to exactly the right point and no further — hence hard water, by altering the length of the fermenting process, will affect both these when fermentation is carried out under precisely the same conditions with hard water as with soft. Further, as the keeping moist of bread depends largely on the degree of change pro- duced in the gluten and other constituents, it is quite possible that the rate of drying may be affected by the use of hard water. Some years ago one of the authors made a series of experiments on the manufacturing scale on the comparative advantages of hard and soft water for bread-making purposes. The use of a water- softening plant was afforded him by the inventors, and over some weeks the character of bread made with the very hard water of the district compared with that made from the softened water. The general conclusion was that no very great difference was caused, or at least no difference that could not be produced by other modifications under the control of the baker, such as slight alterations of the blend of the flour, or mode of fermentation. So far as it went the action of soft water was considered, everything else being equal, an improvement on the hard. 528. Objects of Bread-making. — The miller’s art is directed to the task of separating that part of wheat most suitable for human food from the bran and other substances whose presence is deemed undesirable. The flour thus produced requires to be submitted to some cooking operation before it is fitted for ordinary consumption. Given the flour, it is the baker’s object to cook it so that the result may be an article pleasing to the sight, agreeable to the taste, nutritious, and easy of digestion. It is universally admitted that these ends are best accomplished by mixing the flour with water, so as to form a dough ; which dough is charged, in some way, with gas, so as to distend it, and then baked. The result is a loaf whose interior has a delicate, spongy structure, which causes good bread to be, of all wheat foods, the one most readily and easily digested when eaten. This charging with gas is most commonly effected by fermentation, but other methods are also to a limited extent adopted : these will be described in turn. Fer- mentation has one great advantage over other bread-making processes, ]n that it not only produces gas, but also effects other important changes in certain of the constituents of flour. D D 402 THE TECHNOLOGY OF BREAD-MAKING. 529. Definitions of various Stages of Bread-making.— The methods employed in the manufacture of bread differ in various parts of the country : it will be well to first give a few definitions, and then proceed to describe and discuss the principal methods and their underlying principles. 530. The Ferment. — ^Among the older bakers the first step in bread- making was the preparation of a “ ferment.'' This most commonly con- sisted of potatoes, boiled and mashed with water into a moderately thin liquor, to which a little raw fiour was generally added. The yeast was next introduced, and fermentation allowed to proceed until the whole of the fermentable matter was exhausted, and a quiescent stage reached. The essential point about a ferment is that it shall contain saccharine matters and yeast stimulants in such a form as to favour growth and reproduction of yeast, and growth and reproduction in a particularly vigorous condition. For this purpose it is necessary that the ferment be not too concentrated, because no yeast reproduction occurs with too great a degree of concentra- tion. On Briant's authority the following table is given in the Quarterly Trade Review {Bakers’ Q.T.R.) : — 6 10 14 19 25 36 Concentration of the Medium in which Yeast was grown. per cent, of solid matter Extent of Yeast Reproduction. 6*60 times. 7-37 „ 14-20 10-10 „ 12-50 „ No reproduction, of solid matter is here indicated Independently of this, too, the A medium containing about 14 per cent as being most favourable for reproduction, actual quantity of ferment, as compared with quantity of yeast, is of im- portance ; for on referring to Adrian Brown on fermentation (Chapter IX.), it is seen that too great a crowding of yeast cells, independently of the com- position of the liquid, may permit fermentation, while absolutely inhibiting reproduction. The introduction of raw flour possesses some interest in view of the light thrown on the toxic nature of flour toward yeast in paragraph 378. Such raw flour cannot act as a stimulant to the yeast in the ferment, but may possibl;^ serve to inure the yeast to the effects produced thereon by flour. Various substitutes for potatoes may be used in the ferment ; among these are raw and scalded flour, malt, malt extracts, and other preparations. 531. The Sponge. — This consists of a portion only of the flour that it is intended to convert into bread, taken and made into a comparatively slack dough, with a portion or the whole of the water to be used in making all the flour into bread. The yeast or the “ ferment " (together with usually a small proportion of salt) is incorporated into the sponge. Sponges con- taining the whole of the water are termed “ batter " or “ flying " sponges. Because of its greater slackness, compared with dough, fermentative changes proceed more rapidly in the sponge. One of the authors made a series of observations on small fermenting sponges made in the laboratory with distillers' yeast ; these were very slack, and the number of yeast cells was counted by means of the haematimeter immediately on mixing, and again subsequently at intervals of about two hours. Not only was there no repro- duction, but the cells present gradually lessened in number, doubtless as a result of disintegration of those deficient in life and vigour. From this, and the reproduction table given under the heading of Ferment, the con- clusion is drawn that no reproduction whatever of yeast {Saccharomyces cere- visice) occurs in the sponge. BREAD-MAKING. 403 532. The Dough. — This consists of the whole of the flour to be used, together with the whole of the water and other constituents of the bread, whether mixed straight off or with intermediate stages of ferment and sponge. 533. Various Methods of Bread-Making. — Among these may be included the following : — Dough made right off — Off-hand or Straight Doughs. Ferment and Dough. Sponge and Dough. Ferment, Sponge, and Dough. Flour Barm, Sponge, and Dough — Scotch System. A useful classification of bread-making processes on this principle is given in an article on “ The Best System of Bread-Making,"" contributed to the National Association Review (late Q.T.R.), by W. T. Callard. The following arrangement has been suggested by Callard"s paper : — 534. Off-hand Doughs. — In this system the dough is made direct, with- any preceding stages of ferment or sponge. Types of Bread made hy Method. — Sometimes employed in making tin bread (^.e., bread baked in tins), but also at times for making crusty bread. , Flours Used. — Strong patent flours, mixed very slack for tin bread. Strong London households for crusty cottage bread. Dough- Making. — Generally from IJ lbs. to 2 lbs. of distillers" yeast taken to the sack (280 lbs.), with sometimes a little brew^ers" yeast in addition. Formerly from 10 to 14 lbs. of boiled potatoes were also added, but this 'appears to be no longer the rule. Salt from 3 to 3J lbs. per sack. The slack tin-bread doughs, containing 70 quarts w'ater per sack, are frequently made by hand, and fermented at a temperature of about 76-80° F. wdien mixed : they lie for about ten hours, and yield about 104 loaves per sack. For cottage bread the dough is made much stiff er, about 60 quarts of w^ater per sack, and usually allowed to ferment at a higher temperature, so as to be ready in about six hours. These tight doughs are generally made by machinery, or else the dough is made at first somewhat slack, and then “ cut back "" and dusted up at intervals. Economic Advantages and Disadvantages. — All labour of sponging and extra manipulation saved, bread produced in less time, only one blend of flour and one doughing operation. An increased cost results from the large quantity of yeast required ; also number of troughs and consequent space necessary is considerable. Character of Bread — Appearance. — Very red and fiery in crust, not clear in the partings of the crust, volume fair. When used for cottage bread, a small and rough-looking loaf is the result. Yield. — Large, the high proportion of yeast enabling the Hour to carry considerable quantities of water. Flavour. — Sw^eet, but somewLat neutral at times, and even harsh, when fermentation has been pressed to the utmost extent. In cottage bread when forced, to get a big loaf, there is often a tendency to sourness. Texture. — Poor, loaf devoid of silkiness or pile, holes of aeration unequal, and cottages small and close. Colour. — Dull, and devoid of sheen. Moisture. — High, even to clamminess in some loaves. Summary. — A system in which colour and appearance are sacrificed to moisture and convenience of w^orking. 535. Ferment and Dough. — ^As the term implies, this bread-making system is one in wfiiich a ferment and dough are employed. Types of Bread made hy Method. — Used very largely in London and 404 THE TECHNOLOGY OF BREAD-MAKING the South of England in the manufacture, of crusty bread, and also well adapted for tin bread. Flours Used. — These should be fairly soft, and spring Americans should not exceed 40 per cent, of the whole mixture. Of hard wheat flours, Rus- sians seem to suit this method of bread-making better than the spring American, owing to their glutens mellowing down more rapidly. Some bakers who work by this method claim to use English wheat flours to the exclusion of all other varieties. Winter American patents and also Hun- garian flours answer well in this type of bread. The Ferment. — This most frequently consists of from 10 to 14 lbs. of potatoes to the sack, boiled or steamed, and then mashed with water so as to yield about 3 gallons of liquor. Brewers’ yeast is frequently used in ferments, although recently distillers’ yeasts have been similarly worked. The ferment is “ ready ” in about six hours. Various substances are em- ployed as substitutes for potatoes in ferments. Dough-Making. — The ferment is taken, together with about to 3 lbs. salt to the sack, w^ater over all to the extent of about 56 quarts to the sack, and allow^ed to wwk fairly warm, say 80-84° F. The dough is allow'ed to lie for various times, from two to about five hours. This will depend on the w^orking temperature, character of flour, and strength or quantity of ferment used. Economic Advantages and Disadvantages. — After the labour of preparing the ferment, all that of making and breaking down the sponge is avoided ; there is but one blend of flour required ; and altogether the cost of manipula- tion is very little more than that of off-hand doughs subsequent to the ferment. It has the advantage that comparatively few troughs are neces- sary, because in most cases each can be used several times over during the day’s wwk. The yeast required is not high in amount, but the potatoes used sensibly increase the cost of production, and from their dirty character are a nuisance in the bakery. Character of Bread — Appearance. — Loaf is usually well risen, bearing in mind the class of flours employed. The crust is rough, inclined to break, and usually “ short ” and crisp in texture. Is bright and clear, except when too strong dark flours are used. Yield. — Small, because soft flours are generally employed, say about 90 loaves to the sack. Flavour. — Good, and particularly suited to the London palate, there being considerable sw^eetness. As in all cases where ferments are used, there is danger of “ yeastiness,” unless care is taken that the ferment is not allowed to stand sufficiently long for lactic or other foreign fermenta- tion to proceed unduly at the close of the alcoholic fermentation. Texture. — Close and even {i.e., holes of aeration regular), but not silky. Colour. — Good, with nice bloom ; crust tendency to browmness, but should be free from any foxy tint, the result of absence of very hard flours. Crumbs clear and bright, but comparatively devoid of sheen. Moisture. — Fair, w hen bread is first made ; but all bread of this kind has seen its best twelve hours after leaving the oven Summary. — A very useful system of bread-making, w^ell adapted to districts where bread is eaten very fresh. 536. Sponge and Dough. — This is probably the most wddely used of all l)read-making methods, and evidently therefore adapts itself w^ell to diversi- fied requirements. Types of Bread made hy Method. — Almost every kind of bread, from the tightest crusty bread dough to that for the slackest tin bread, may be made in this manner. BREAD-MAKING. 405 Flours Used. — Practically every variety of bread-flour offered to the baker can be utilised in this method ; the great advantage is that hard flours can be used in the sponge, thus giving them the advantage of long fermentation, while softer flours are appropriately worked in at the dough stage. Sponge- Making or “ Setting.” — A blend of hard flour is used for this purpose, and a quantity taken equal to from a quarter to a half the whole of the flour to be used. A frequent plan is to take a bag (140 lbs.) of spring American patents for the sponge, and a sack of home-milled softer flour for the dough. Sufflcient water must be taken to make the sponge-dough very slack, say from to 8 gallons of water to the 100 lbs. of flour. Distillers" yeast is now most frequently employed, and a quantity may be taken of from 6 to 10 ounces to the sack of flour (over sponge and dough) ; if wished brewers" yeast may be employed instead, but the quantity must considerably vary according to the strength of the yeast. A little salt is usually added to the sponge, say about J lb. to the sack. Formerly potatoes were occa- sionally added direct to the sponge : this custom seems now, however, almost obsolete. On being set, the sponge is allowed to ferment for from six to ten hours, according to the temperature, quantity of yeast, character of flour, and other considerations. In machine-bakeries sponges are usually set somewhat stiffer than where sponges and doughs are made by hand. The Dough. — The sponge, when ready, is taken, mixed with the remainder of the flour, the water, and the salt. Soft, flavoury flours are introduced at this stage, and the dough allowed to lie about two hours. The tempera- ture both of sponges and doughs is governed by how soon either may be wanted, the atmospheric temperature, and other considerations. Economic Advantages and Disadavntages — The adaptability of this method is one of its great advantages, and also the readiness with which it lends itself to the selection and use of any variety of flour. There is somewhat greater expense in working, because of the double handling in- volved in working the sponge as well as the dough. It is doubtful, how- ever, whether this is appreciable in the hand-made bread bakery, as it amounts simply to making the dough in two instalments in the same trough — there is, in fact, an advantage, as the sponge flour will have had time to soften, and get to work more kindly before the full quantity is worked in in the dough. Character of Bread — Appearance — Almost any shape of loaf is well made in this manner, the bread is bold, and, generally speaking, of good appearance. Yield. — With the great elasticity of the system, as a whole, the yield varies considerably according to the character of flours used. Taking a general average, 93 to 96 loaves per sack is a good proportion. If an excess of hard, strong flour is used in order to get more bread than this, the flavour is likely to suffer. Flavour. — One of the essential characters of this type of bread is that, if well made, it embodies to perfection the natural flavour of the flours, without any adventitious characters introduced with foreign flavouring ingredients. If the flours are well selected, both for sponge and dough, there should be, on the one hand, an absence of that “ rawness "" characteristic of under fermentation, and of any harshness resulting from destruction of all moisture and sweetness-conferring constituents by over fermentation. Texture. — The bread should have a good pile, crumb even, white and silky, with full sheen on the fibre of the bread. Colour. — The crust should be golden brown, without foxiness or abnormal paleness. In the crumb the colour advantage of the class of flour used should be fully developed. 406 THE TECHNOLOGY OF BREAD-MAKING. Moisture . — Bread made in this manner is free from any clamminess, and may easily pass over the line into harsh dryness — this, however, is a fault that should not occur, rather than a necessity of the method. From the very even sponginess of the bread, although when fresh cut it may be very moist, yet it tends to rapidly dry out when cut slices are allowed to lie about. But when properly made, this bread retains its moisture in the uncut loaf remarkably well. Summary . — An interesting point about the sponge and dough method is its comparison with that of ferment and dough ; both have their advan- tages, but that just described for most purposes has the preference. Com- paring breads made by the two methods, ferment and dough made bread is at its best when quite fresh ; wLile suitably made sponge and dough bread retains its eating properties considerably longer. 537. Ferment, Sponge, and Dough. — This is essentially a combination of the tw^o immediately preceding methods, and is frequently chosen where brewers’ yeast is used, as the ferment exerts a specific and valuable action on yeast of that description. A ferment being employed, instead of adding yeast to the sponge direct, a description of the sponge and dough method applies also to this process. One of its advantages is that it permits more individuality in character of the bread than where a compressed yeast is used, which can be freely purchased by any baker. When by means of a “ ferment ” the baker practically makes his own yeast, he becomes liable to the risks as well as the advantages accruing from being his own yeast manufacturer. This method is frequently associated with the manufacture of patent yeast by the baker himself. The whole of the various methods previously described are susceptible of the same modifications, except perhaps tight, off-hand, crusty bread doughs which would rise with diffi- culty under the action of this usually comparatively weak yeast. 538. Present Review of Bread-making Methods, Callard. — ^Mr Callard has kindly furnished the authors with the following note on his paper herein quoted : — “ In the intervening sixteen years since writing the paper referred to,, considerable changes have taken place in the general practice of bread- making. In the main these changes are due to two causes : (1) the great improvement in the preparation of compressed yeasts, and (2) the advance of English milling. (1) Compressed yeasts to-day are of a much higher quality and lower price than when that paper was written. They are much less susceptible to atmospheric changes, and consequently are less damaged in transit. They are stronger, or ,to be more correct, they mature quicker in the dough than did yeasts of years ago. This has enabled bakers to dispense with ferments or sponges, and the system of straight doughs has become almost universal. Where the sponge and dough system survives to-day, it is on account of attachment to old methods and not because of the necessity of so treating the yeast. (2) The English miller has for many years aimed at producing a flour of an all-round quality, avoiding harshness on the one extreme and soft- ness on the other. He has tried to produce a flour capable of being used alone. ‘ In this he has succeeded, with the result that the flours of to-day are more mellow than in the past and require less softening during the process of fermentation. The straight dough system (off-hand) with IJ lbs. to IJ lbs. of yeast, taking about 5 hours to the oven, is general. This occupies the same rela- tive place at present as the sponge and dough did when the paper was published. Here and there a modified ferment is used in conjunction with BREAD-MAKING. 407 it to give the yeast a start. When the desire is to shorten the time the yeast is increased, in fact with automatic plants 6 lbs. of yeast is used to the sack, and the dough passes from the mixer to the divider without delay.'' {Personal Communication, October, 1910.) 539. Flour Barm, Sponge, and Dough — Scotch System. — The flour barm is practically a combination of the making a baker's malt and hop yeast with a slow, scalded flour ferment. The preparation of the flour barm has been fully described in the earlier part of this work, page 249. Type of Bread made hy Method. — This is the well-known close-packed Scotch brick," being a high and comparatively narrow loaf, prepared from tough, hard flour of the highest class. Flours Used. — In sponges, strong patents or straight grades from Duluth or Russian wheats. In doughs, winter Americans and softer, but still tough, home-milled flours. Sponges. — These are known as “ half " or “ quarter " sponges, and consist of either the half or quarter of the w4iole liquor employed to the sack of flour. The requisite quantity of flour barm is taken, for which, how- ever, distillers' yeast may be substituted without materially altering the character of the bread. About 6 lbs. of salt are used to the sack, one-sixth of which goes into the sponge. Doughs. — These are made in the usual way, but it is customary to give the dough a very thorough working after it has laid some time. One of the most suitable ways of doing this is by passing the dough repeatedly through a dough-brake. Economic Advantages and Disadvantages. — The cost of production is, according to the views of the Scotch baker, very low, as he views the yeast as costing him very little, the flour used coming back into the bread. This is not quite correct, because a certain portion must have been changed into alcohol and carbon dioxide during fermentation ; and, again, the labour of preparation must cost something. Character of Bread — Appearance. — The appearance is attractive, the loaves are high, and the sides, where they have been separated from each other, have a very smooth, silky appearance. Yield. — Large, the character of the flours used permitting this, and also the fact of most of the bread being close packed. An average yield in a large factory has for some months been as much as 10 1 quarterns per sack. Flavour. — Characteristic, and marked by the presence of a decided acidity of pure and pleasant taste, due largely, if not entirely, to the pre- sence of lactic acid. The large quantity of salt used gives a saline char- acter to the taste, immediately recognised by the English palate, which also usually misses the sweetness generally found in the best qualities of bread made in the south. Texture. — Scotch bread has the perfection of texture, being silky with large bulk and pile, and small regular holes of aeration. Colour. — The long system of baking employed gives the crust a dark brown colour, and hence the bloom of crust is not such an important char- acteristic as in south country crusty bread. The crumb is exceedingly white, but has comparatively rarely the creamy, yellow bloom seen in some of the bread made in other localities. The sheen of the bread is remarkably distinct, the holes having a rich, full glaze. Moisture. — Good, and the bread keeps remarkably well. 540. Modern Bread-making Practice. — It has been the wish of the authors to give as representative an account as practicable of the modes of bread- making at present generally adopted. With this object in view they wrote 408 THE TECHNOLOGY OF BREAD-MAKING. personally to a large number of representatives of the baking trade, and have been favoured with the following replies. Their best thanks are due, and are here tendered, to those gentlemen who have so kindly assisted them. The following printed list of particulars required was forwarded and answers requested ; which should as well as possible give the general practice of the district rather than the methods of individuals. It was also pointed out that no information was wished that would be in the nature of trade secrets : — General Bread-making Processes. Employed in (town or district) : — I. Flours used, how selected and blended, and in what proportions. (Varieties or types of flour, and not names of millers, are desired.) II. Nature and type of yeast used. III. Bread improvers (if any), including malt extract, sugars, fat, milk, mineral salts. IV. Bread-making processes, including quantities of ingredients, flour, yeast, salt, bread improvers, milk, water, etc. Length of time of fermenta- tion, system, and temperatures. How doughs, etc., are handled. V. Nature and type of bread produced. VI. Remarks. Replies. 541. Birmingham, hy Mr. Thomas Fletcher. — I. Comparatively little foreign flour is now used, but almost exclusively English milled flour, and mostly from Birmingham and surrounding dis- trict. The large port millers have a good share of business here, however. The varieties of flour used are first and second patents and seconds flour. Not much blending is necessary. II. Most of the prominent types of yeast are used here. III. Bread improvers (chiefly malt flour) are extensively used. Fat of some kind is being added by some bakers to the best quality bread, malt extract, milk, etc., being now limited to varieties of brown or whole-meal bread. IV. The system of straight doughs is almost exclusively adopted now. The average time occupied from start to finish extends from four to seven or eight hours, and the quantity of yeast used is varied accordingly. V. Crusty cottages, and split batch, form the major proportion of bread sold. Pan loaves, round and oblong in shape, are produced in lesser quantity. 542. Brighton, by Clark’s Bread Co., Ltd. — I. Mostly English milled flour, comparatively little foreign compared with twenty years ago, during which time there has been a marked general improvement in the standard of quality. Information as to other Arms’ exact mixtures and methods of blending not readily obtainable. The principle adopted by the writers lias been the careful selection of flours for absolute purity and maximum nutritive value. In pursuance of this policy they select flours which are unbleached and free from all mineral additions. II. Distillers’ compressed yeast. III. Improvers not very largely used, the principal ones being malt extract, and to a lesser degree malt flour. IV. Straight and fairly tight doughs are now almost universal in this district. Salt about 3J lbs. to the sack. Short system of fermentation, from 4 to 6 hours ; yeast from 2 lbs. to I lb. The writers make it their endeavour to arrange the fermentation so as to get thorough ripening of BREAD-MAKING. 409 the gluten of the flour and consequent digestibility without any approach to acidit}^ or overworking. The doughs are hand-made in the smaller bakeries, while in the larger more or less complete machinery installations have been made. These include kneading, dough-dividing, and automatic moulding machinery. Ovens used are of various types, principally side- flue, and steam drawplate ovens. V. Mostly crusty cottage and coburg 2-lb. loaves. Usually well baked. 543. Crewe and District, by Mr. W. J. Wilding. — I. Practically all flours used are made from blended w4ieats, chiefly Plate and Russian (various types), English, Canadian, Australian and American, winter wheats. But it largely depends on the world’s harvest. We are fortunately situated near to Liverpool, which gives to the miller a better advantage than one situated farther inland, and then we have the large Liverpool mills turning out first-class blended flours ready to use without further mixtures. II. All bread produced in the district is made with distillers’ yeast. III. I do not think there are much “ improvers ” used besides sugar and, in some cases, a little malt extract, except milk and lard to fancy breads. IV. We have several systems in use, each firm using the one best adapted to his class of business and convenience of working. For instance, one large firm works on the sponge principle, both long and short ones, the former being set in the afternoon ready for night w^ork, and the latter later to follow on. Others make all straight doughs, including the writer, who uses from 1| lbs. to 2 lbs. yeast. Tin Bread. — 1 lb. sugar (beet preferred), SJ lbs. salt, 16 gallons water or more, 280 lbs. (flour first patents). Dough when made to be 80-84° F., according to the weather. Let stand 1 J hours w'ell handed up, and should be ready to tin up 2J to 3 hours after making into dough, baked in oven at 400° F. after well proving. Cottage. — 2 lbs. yeast, SJ lbs. salt, 1 lb. sugar (beet), 280 lbs. flour (best patents). Dough when made to be 80-82° F. Cut back twice and should be ready to scale off in hours after mixing. Scaled and handed up in boxes, proved and moulded, proved again and set in oven at 480° F. or near. V. Varies from the well proved tin to the close-set crumby loaf. About equal quantities of tin and cottage are made, but the majority of the bread produced is seconds quality. 544. Eastbourne, by Mr. G. B. Soddy. — I. Principally town-milled flour, average quality, “ whites,” though in some cases, a higher grade is used. II. Distillers’ compressed yeast. III. Malt and sugar. IV. Straight doughs, usually fairly tight (about 14 gallons of water per sack). Salt, about 3 lbs. to the sack. Short process of fermentation gener- ally in use. Doughs are invariably well-finished, i.e., carefully handed up and moulded. Dough is well baked. V. Crusty bread, well finished, of good appearance, and quality generally very good. VI. The above generally represents the methods and results achieved in this towm. There are a few cases where a low grade flour is used and where the workmanship is not good, but these are the exception, not the rule. 545. Leeds and District, by Mr. C. H. Slack. — I. The flours used are principally those supplied by the port millers, 410 THE TECHNOLOGY OF BREAD-MAKING. both on the east and west coasts, the baker buying the particular grade that happens to suit his requirements. In some cases more than one grade of a particular miller’s flour may be used and the two blended, or the flours from two or more mills may be treated in the same manner, more often than not without any regard to definite proportions, the flour being bought more through some monetary consideration than for any specific purpose. The varieties of flours are both of the medium strength and soft. Home baking being largely carried on, and flour for this purpose being almost entirely retailed by the grocer to the housewife, the bulk of the flour used is supplied with that particular object in view, viz., to satisfy the demand for whiteness which the housewife usually considers to be the criterion of quality ; consequently, the baker, more to meet this demand of the home baker than from any other reason, deals principally with the miller who may supply this type of flour. Since many of the millers have migrated coastwards, and with increased areas to distribute their products over,^ there has been more uniformity in the supply, and the general quality has improved. A few years ago parcels of American spring and winter flour were to be bought, and were used prin- cipally by wholesale bakers, who blended with the products of local mills, in varying proportions, with the idea of strengthening the mixture, but to-day one rarely meets with any samples being offered. Parcels of Aus- tralian, Russian, Argentine, and French are sometimes to be met with, which are offered by importers or agents ; bakers, however, usually do not care to touch them unless there happens to be some special advantage in price. The J ewish bakers as a rule use lower grades than the average baker, quality not being of as much matter as price. II. The yeast used is principally distillers’, both pure and mixed ; though pure is mostly in use, and is both of the quick and slow working type. III. With regard to bread improvers those in most general use are some kind of malt extract, sugars, glucose, fats, cooking oils, milk, fresh and in the form of powder ; and though not extensively used, there are cases on record of the use of calcium phosphate, calcium sulphate, cream of tartar, and bi-carbonate of soda. IV. The methods employed are much the same as in other parts of the country. Among most bakers in anything like a large way of business, the doughs, whether made by hand or machine, are in sack batches or multiples of the same, and extends over periods varying from 1 to 12 hours with quantities of yeast varying from lb. to 7 lbs. per sack. Yeast at the rate of 5 lbs. per sack is quite in common use among smaller bakers, while in small breads the rate per sack is much higher. The off-hand process is the one most generally followed, sponge and dough, and ferment and dough processes are rarely heard of except in the case of small bread and rolls. The use of the thermometer in bread-making operations is not so fre- quent as is commonly supposed. The average journeyman baker is not sufficiently versed in the line he should take in the event of his doughs being warmer or colder than he may have calculated, and therefore the use of the thermometer is more or less ignored. But it is invariably found that where the baker has had the advantage of technical instruction, the thermometer is much more appreciated, and the resultant bread is of a more regular and uniform character. While machinery is being more generally adopted, there are few bakeries where anything like an automatic bread-making plant is in use ; all types of mixers are employed, but the rotary type preponderates. Gas engines. BREAD-MAKING. 411 have given place to the more convenient electric motor, especially where room is of the first consideration. The following are actual processes in general use : — 1. 280 lbs. flour, lbs. yeast, 3Jlbs. salt, 8 to 16 oz. malt extract, 56 to 60 quarts of water. Dough 80° to 84° F. ; 4 hours from making to oven ; cut back at 1 hour, tabled at 2 to 2J hours. 2. 280 lbs. flour, 4 lbs. yeast, 2J lbs. salt, 8 oz. malt extract, 60 quarts water. Dought 90° F. ; 2 hours from making to oven, including one good kneading. 3. 280 lbs. flour, 60 quarts water, 1 J lbs. yeast, 1 lb. malt extract, 3J lbs. salt. Dough 90° F. ; 5 hours to oven ; cut back at 2i hours. 4. 280 lbs. flour, 64 quarts water, 2J lbs. yeast, 3| lbs. salt, | lb. malt extract. Dough 86° F. ; 4J hours to oven, including one cut back at 2 hours. 5. 280 lbs. flour, 56 quarts water, 2J lbs. yeast, 2J lbs. salt, | lbs. malt extract. Dough 80-82° F. ; 4 hours to oven, including two cuts back. All the above were made both by hand and machine and produced fine flavoured commercial bread. The types of flour used were first and second patents. Among small bakers the following are fair samples : — 1. 14 lbs. flour, 3 quarts water, 2 oz. yeast, 2 oz. salt, J oz. malt. Dough 80-86° F. ; 4 hours from finished making to oven. Hand made, and pro- duced bread of beautiful texture and flavour. 2. 14 lbs. flour, 3 quarts water, 3 oz. salt, 1 oz. malt, 3 oz. yeast. Dough 82° F. ; 3 hours 50 minutes from making to oven, including two cuts back. 3. 28 lbs. flour, 6 quarts water, 8 oz. yeast, 6 oz. salt, 2 oz. malt. Dough 80° F. ; 3 hours to oven. Samples of bread made by this method have often been in my hands, and from the appearance of the bread only it was perfect in texture and extraordinary in colour. Investigation by means of carefully made comparative tests showed the use of milk powder, both skim and full cream. V. The type of bread made is mostly of the tin variety, but cottages, coburgs, cakes, whole-meal, wheatmeal, malt and the bulk of the proprietary breads are also made in varying quantities, and in an extraordinary number of weights and sizes, from 12 oz. to 8 lbs. 546. Leicester, by Mr. W. T. Callard. — I. A very small proportion of foreign made flour is used. Supplies are principally from the port millers ; midland millers supply about one- tiiird of flour used in good seasons. II. Compressed yeast entireh^ III. Sugar, general ; malt extract to a limited extent. IV. Almost entirely straight dough ; IJ to 1 J lbs. yeast to sack ; 3 Jibs salt. ]\Iilk not at all except for bona-fide milk bread. Water 14 gallons to sack of English local milled flour ,,15 ,, ,, port milled flour „ 16 ,, ,, ,, ,, ,, for tin bread. Doughs are usually machine made. The drum type is very general for hand and power. Dividers are not in general use, moulding machinery is employed by one firm only. V. Mainly cottage and tin bread. VI. Three qualities are usual with the larger bakers. The quality has much improved in recent years. 547. Liverpool, by Messrs. Geo. Lunt, Sons & Co., Ltd. — I. English, American, Continental, and also Colonial flours used. Se- lection, according to requirements and prices ruling. Should foreign flour be relatively cheap then special efforts are made to use same, blending strong Americans with weaker English or Colonial. 412 THE TECHNOLOGY OF BREAD-MAKING. II. Distillers’ yeast. III. Bread improvers not generally used. IV. Straight doughs, 4 to 6 hours. Salt generally 3 lbs. per sack, varying quantities of yeast and water according to variety of bread, tem- perature various, doughs cut back either by hand or aerating machine. V. Tin and oven bottom (upset), two or three grades. Report by another Liverpool firm . — I. Principally Liverpool milled flour, which as a rule requires no bleaching. II. Practically all distillers’ yeast, with the exception of a few small bakers who still use brewers’ barm. III. Malt extract and dry malt flour. Sugar, fat, and milk are rarely used in ordinary household quality bread but are largely used in best or milk bread. Mineral salts are coming into use under various names as bread improvers. IV. Bread is principally made on a straight dough process allowing from 5 to 6 hours in dough. Quantities taken are : — 280 lbs. flour. 150 lbs. water for tin or pan bread. 130 lbs. water for oven-bottom or crumby bread IJ lbs. yeast. 3J lbs. salt. 1 lb. malt extract. The resultant dough to be of a temperature of 78-80° F. The dough is left to prove for 3 hours, then cut back, let prove for another hour, turned over and scaled in another hour. It is scaled by machinery, allowed to prove for 20 minutes, then moulded in its required shapes, allowed to stand 15 minutes, and then put into the oven and baked at a tem- perature of 500° F. for tin heat, and 450° F. for crumby. V. Liverpool bread has for many years been divided into two main types of tin bread and oven-bottom bread. The proportion of tin bread gradually increases. There has been a decided tendency during recent years on the part of the public to buy smaller loaves than formerly. At one time 6 and 8-lb. loaves were greatly in demand ; now there are very few made. Latterly, also, a light crumby loaf seems to be coming into favour. 548. London, West End, by Messrs. Bouthron & Co. — I. Flours, 2 parts town whites, 1 part London top-price patents, I part country supers. II. Compressed distillers’ yeast. III. Malt flour. IV. Ferment and dough. Ferment set at 85° F., adding 1 lb. (per sack) of scalded malt flour. Yeast, I lb. per sack. Dough — 1 sack flour, water making total liquor up to 14 gallons, temperature 110°, salt, 3 lbs. Tem- perature of dough, 84°. Dough cut back at 4 hours, scaled at 5J hours, in oven at 6J hours. Start to finish, 9 hours. V. Crumby bread and crusty cottage. VI. With the large variety of breads made, the various doughs neces- sarily differ in detail. The above must be taken as an outline of the general system followed. 549. Macclesfield, by Mr. G. B. Gee. — I. English milled flours. II. Almost universally compressed Continental and British yeasts. IV. Ferment and dough ; water about 17 gallons per sack for tin bread, and about 13 gallons per sack for oven-bottom bread. BREAD-MAKING. 413 V. Largely tin bread of light consistency. A small proportion of cottage and other shapes. 550. Malvern, by Mr. T. Percy Lewis. — I. Good grade millers’ blend, very little imported flour. II. Distillers’ compressed yeast, Dutch and British. III. Malt extracts and malt flour only. IV. All small bakers use half sponge ; larger bakers, off-hand. to 4 lbs. of salt per sack, and usually 1 lb. malt extract. Most ovens are still side-flue, but steam patents are coming into favour. V. Mostly 2-lb. coburgs (locally termed “ gullies ”). VI. The class of bread is much above the average households of larger towns, very little plain tie or households flour being used. 551. Manchester and Salford, by^Mr. A. Worsley. — I. Flour milled in England from foreign wheat (Australia, Manitoba, Karachi, Russia, River Plate), selected for their strength and bloom. Most bakers would use about three parts of this with one part of English milled flour made from half foreign and half best English wheat, and used for the purpose of giving sweetness, flavour, and moisture to the bread. II. Distillers’ yeast. III. Any bread improver, but mostly malt extracts, used for the purpose of assisting fermentation and making the dough work more quickly and regularly. IV. Nearly all the Manchester and Salford ^bakers use a dough mixer 1 J or 2 sack capacity. They make a straight dough as follows : — 280 lbs. flour. IJ lbs. yeast (IJ or If lbs. for first round) lbs. salt. J to 1 lb. bread improver 16 J to 18 gallons of water. Usually the dough making is done first thing for the day, say four, six,, or eight batches of bread. Temperature of water for first round about 95° and reduced to 85° for the later batches. The quantity of yeast used is also reduced. Length of time about 4 hours. Dough knocked down once. V. Probably 85 per cent., or even more, of the bread made in Manchester and Salford is tin bread, the remaining 10 or 15 per cent, being cottages, cobs and brunswicks. The bread is of good quality and volume. 552. Nottingham, by Mr. L. E. Turner. — I. Eighty per cent, of the flour used here is port milled, and comes from Hull, York, Grimsby on east coast, and Liverpool and Bristol on the west. The remaining 20 per cent, is divided between the smaller country mills and the larger inland ditto. II. Dutch yeast is used principally and has by far the largest sale. No brewers’ or patent yeast is now used. III. Only knows of malt extract being used, and that not in large quan- tities. Milk and fats are used in fancy breads. IV. The great bulk of bread is now made on the short process — straight doughs, etc. 280 lbs. flour, IJ lbs. yeast, 3J to 4 lbs. salt, 16 J gallons of water at 95° F. Dough is made and after 2J hours is cut over, left another hour, and is then scaled off into tins and proved about 20 minutes and is then baked. For cottage bread only 134 gallons of water are used, and after the dough is scaled, the pieces lie for 20 minutes in boxes to prove before being moulded up for the oven. V. Two- thirds of the bread made here is tin bread in 2-lb. loaves, one. 414 THE TECHNOLOGY OE BREAD-MAKING. third oven-bottom, also 2 lbs., in cottage and coburg shapes, three-quarters of them the latter. VI. All the larger bakeries use machinery, and most of the smaller ones have small plants also, hence the popularity of the straight dough system. The great competition among bakers causes them to use more water than is good for obtaining the best results from a quality standpoint. 553. Plymouth, by Mr. Henry J. R. Matthews. — I. One-fourth American spring wheat patent, three-fourths English milled patent. II. Dutch compressed yeast. III. Malt extract. Dried milk powder. IV. Four hours' sponge, 2 lbs. yeast, 3 lbs. salt, J lb. malt to the sack of flour. Dough made and allowed to lie IJ hours. Temperature for sponge, 90° ; for dough, from 80 to 90° F. ; the usual temperature of flour being from 75 to 80° F. V. Superflne bread, principally 2-lb. loaves of various shapes. VI. Steam drawplate ovens are principally used. Bread in oven 50 minutes, temperature 480° F. 554. Belfast, by Mr. Geo. Inglis. — I. American springs and winters, and United Kingdom blends, mostly top patents. Bought from samples, or mill’s brands, and blended by mixers, sifters, and conveyers according to requirements. II. Distillers’ compressed yeast (local manufacture). III. Great diversity of practice, many Arms only using these in fancy bread. IV. Principally sponge and dough, but straight doughs increasing. Six to ten hour sponges. Mixers, dividers, moulding machines, provers, and several automatic plants in use. V. Mainly 2-lb. square batch loaves, also cottage and pan loaves, and a large variety of small kinds. ' ' 555. The West of Scotland, by Messrs. Montgomerie & Co., Ltd., Glasgow. — •' The Quarter Sponge System . — The first part of the process is the doughing of the quarter. Portions of flour, water and salt are doughed up with the total quantity of barm. The usual time for fermentation is from 10 to 1 5 hours at this stage. The temperature of the water is regulated to suit the time the quarter has to be on the road. The following is an example : — If the temperature of the flour is 64°, the bakery 74°, the barm 60°, to lift the quarter in 15 hours the water should be 80°. For every hour less than 15 hours that the quarter has to be on the road, it is usual to raise the temperature of the water by 4°. The temperature of the quarter when lifted should be about 84°. The next part of the process is the stirring. In the stirring more flour, water and salt are stirred into the quarter. The temperature of the water varies according to the time in which the sponge has to be lifted. If in tlie stirring the flour is 66° and the quarter 84°, the temperature of the water, if the sponge has to be lifted in 1 hour, would be 90°. The temperature of the water should be decreased by 10° for every \ hour longer in the sponge. It is usual to raise tlie temperature of the water by 2° for every degree the quarter is below 84°, and vice versa. When it has turned about one inch, the sponge is doughed with the rest of the flour, salt and water. The temperature of the dough should be about 80°. Tlie water used in the dough will be about 74° if the flour is 66® and the sponge 84°. The dough is allowed to lie for about 1 J to 1| hours. It BREAD-MAKING. 415 is then weighed off and laid into cases, where it is allowed to lie for about 15 minutes. The loaves are then moulded and placed in cases or setting racks, according to the style of the oven in use ; in cases for Scotch ovens and setting racks for drawplate ovens. The loaves are baked at a temperature of from 400° to 450° Fahrenheit. The time occupied in baking varies from IJ to 2 hours, according to the heat of the oven and the condition of the dough. (Further reference is made to Scotch bread-making methods in a sub- sequent part of this chapter. 556. Cardiff and District, by Mr. W. J. Travers. — I. Mostly English milled. Demand for American Patents greatly decreasing. English flour is now blended in the process of milling to suit local requirements. II. Distillers’ yeast. III. Malt extract and malt flour generally used, some using sugars and fat. IV. Dough generally consists of 280 lbs. of flour, 14 gallons water, 1 J lbs. yeast ; according to time and general conditions, 3J to 4 lbs. salt ; about 1 lb. malt extract or malt flour. Fermentation, generally short process, from 3 to 6 hours. Dough generally made by machinery. V. All shapes of bread manufactured, mostly 2 lbs. in weight ; not too much proof, as the public like a fairly firm and close loaf. 557. Toronto, Ont., Canada, by The Nasmyth Co., Ltd. — I. Hard flour milled from Manitoba and North-West wheats. Soft flour chiefly from Ontario fall wheat. Used in proportion of two parts hard to one part soft, and four strong to one soft. II. Vegetable compressed yeasts used almost entirely, though there are instances of malt and hops yeasts being used also. III. The first four are largely used ; the fifth not to any extent. IV. Straight doughs taking from 6 to 8 hours to the table ; 12 to 14 hour sponges are also used. The following are quantities for two types of bread — Real Home Made. — Flour, 784 lbs. ; water, 420 lbs. ; salt, 14 lbs. ; cottolene, 17J lbs. ; yeast, 6 lbs. ; malt extract, 5J lbs. Temperatures : Flour, 70° ; bakehouse, 80° ; water, 84° ; dough, 82° F. G. Crust . — Flour, 972 lbs. ; water, 520 lbs. ; salt, 18 lbs. ; cottolene, 131 lbs. ; yeast, 7J lbs. ; condensed milk, 13 lbs.; malt extract, 5 lbs. Temperatures : Flour, 70° ; bakehouse, 80° ; water, 86° ; dough, 83 °F. Machinery is extensively used. Mixers, dividers, moulding machines and rounding-up machines are used in the larger shops, and automatic provers are being introduced. The quantity of hand-made bread is small and decreasing. V. Tin bread almost entirely. Our output of hearth baked bread is less than three per cent, of the total, and would probably represent the average. 558. Cincinnati, Ohio, U.S.A., by The Banner Grocers’ Baking Co. — I. Three parts Minnesota patent to one part Kansas hard wheat. II. Compressed yeast. III. Malt extract, sugar, lard, milk, cornflour. IV. Quantities : 850 lbs. flour, 525 lbs. w^ater, 6J lbs. yeast, I2|- salt, 20 lbs. sugar, 17 lbs. lard, 5 lbs. milk powder, 5 lbs. malt extract and 25 lbs. cornflour. A short time ferment is made with the yeast, malt extract, part of the water, and the cornflour. This is added to the dough after the flour is in. 416 THE TECHNOLOGY OF BREAD-MAKING. The temperature of the dough is 84° F., and the time from mixer to bench is 5J hours. V. “ Buster Brown Bread.'' 559. Nappanee, Indiana, U.S.A., hy Mr. A. F. Hartman. — I. Minnesota spring wheat flour. II. Compressed yeast III. Sugar and cotton-seed oil. IV. Straight dough from the following quantities : 100 lbs. flour. 60 lbs. water, 2 of sugar, 1 J of oil, and 1 J of salt. Allowed to ferment until the dough drops in centre, is then cut over, stands one hour, again cut over, and after 1 J hours, to bench and baked in pans. Dough is made at 80°, being 240°, less the heat of the bakehouse and that of the flour, ta get the temperature of the water. The fermented dough when it comes to the bench is at 80-82° F. V. String or pan bread. VI. This system makes a very fine bread, but the sponge system is. more used in Indiana than is that of straight doughs. 560. Further American Recipes. — The following are additional American bread-making recipes kindly furnished by the Malt-Diastase Company of New York. New England Bread, Straight Dough. Eight lbs. corn flour or cereline (flakes) placed in mixer with 4 gallons warm water ; run it for a few minutes, adding 5 lbs. (2 quarts) malt extract. Then add — 34 gallons water (90° to 98°). 2 gallons milk. 3J to 4 lbs. compressed yeast. 4 lbs. sugar. 6 to 8 lbs. lard. 9J lbs. salt. 540 to 550 lbs. flour (3 parts Minnesota spring patent, 1 part winter wheat or Kansas). Dough should have temperature of about 82° to 84°. Make soft dough. Push down when well raised (3 to 3J hours) ; after another half-hour before going to bench cut dough over and let rest a half-hour more, if time allows it. If mush is preferred to meal or flakes, take 40 to 50 lbs. Treat dough same as above. In place of milk you can use dry milk powder and suffi- cient extra water. Don't let the dough get too ripe the first time, so that it falls by simply pushing your hand into it. It must still have sufficient resistance, that is, lias to be cut down. Never use water too hot ; it would be better to warm tlie flour in winter, and chill the liquid used, by running through a colander with broken ice in hot weather. A little more yeast is better than setting dougli too warm. With Sponge. Same as above. Use 17 gallons of the water for the sponge, the remainder for the dough. Be sure and mix mush or flakes in mixer first before mixing dough, and use only 3 lbs. of compressed yeast. Note . — The substance spoken of as cereline consists of cereal matter, gelatinised, rolled into flakes, and dried. Analogous substances are known in this country as flaked rice, flaked tapioca, etc. Mush consists of corn flour, gelatinised into a paste by hot water (3 lbs. of the flour to a gallon of water. ) BREAD-MAKING. 417 Home-Made Bread, for Sponge. 5 gallons water. 14 ozs. yeast (in summer 12 ozs. are sufficient), 70 lbs. flour. Water can have 98° to 100° according to flour. Sponge mixed should be at least 84°. For Dough. 22 quarts water. J quart malt extract. J lb. sugar. 20 lbs. mush (or equivalent in water and flakes). 1 to IJ lbs. lard. 70 lbs. flour. 3 lbs. salt. When mixed, add about J lb. oil, so dough will come out of mixer smooth. Domestic Bread, with Ferment. Make sponge with 5 gallons ferment, J lb. salt and sufficient flour. When it falls the first time add — 10 quarts water. IJ lbs. salt. 1 lb. malt extract. IJ lbs. lard. Take ferment for sponge at 85° ; water for the dough at 82° to 84°. Let dough come twice. This dough can stand a strong flour, but use some winter patent with it. If you wish bread to be a little sweeter, add 1 J to 2 lbs. brown sugar. Ferment , — To one peck washed potatoes (with skin) add sufficient water to cover them well. When boiled soft put in tub, and mash with 3 lbs. flour ; add gradually the potato water and more plain water to make 5 gallons. When cooled to 80° add f pint stock yeast or 3 ozs. of com- pressed yeast. Set away and let rest undisturbed for about 10 hours until it falls. Cottage Bread, for Fine Retail Trade. Set soft sponge with J lb. compressed yeast, 2J gallons water (82° to 84^^ when mixed) and sufficient flour. When raised the second time (about 3 hours) add — 2 gallons milk. 6 quarts water at the same temperature. 21 to 24 ozs. salt. 1 lb. lard. 4 ozs. butter. I lb. malt extract. J lb. sugar. Sufficient flour. A mixture of two barrels strong Minnesota patent and half barrel rich winter patent gives best results. Milk Bread. 9 gallons water. 1 gallon milk. 1 lb. yeast. 16 lbs. mush (or 2 gallons extra water and 10 lbs. maize flakes). 2 lbs. lard. ' EE 418 THE TECHNOLOGY OF BREAD-MAKING. 1 lb. malt extract. 2 lbs. sugar (or more malt extract and no sugar). 3 lbs. salt. 140 to 145 lbs. flour (same quality as for New England). Quaker Bread. 10 gallons water (75° to 80°). 12 to 14 ozs. compressed yeast. 2J to 2J lbs. salt. 1 lb. lard. 12 ozs. malt "extract (or J lb. malt extract and 2 lbs. sugar). 10 -12 lbs. of mush, corn flour or cereline flakes (with extra water) can be added to reduce cost wdthout affecting quahty. Mix into slack dough ; use rather strong mixture of flour, say three parts spring patent, one part winter patent ; part Kansas wheat may be added. Let dough rest first for 3 J to 4 hours. Push down once, let come up again. Don't give too much proof after moulded up. Bake in double loaves in tins — square tins. In winter this dough must be set from 5° to 10° warmer, and a little more yeast may be taken. In many bakeries the Quaker Bread dough is forced to be ready in 3 to 3J hours. The preceding includes not only English, Irish, and Welsh methods, but also a few examples from Canada and the United States, sent by various firms on the American side. 561. Scotch Practice. — This in 'its turn differs considerably from English modes of making bread. For the earlier portion of the following descrip- tion the authors are indebted to an article on Scotch Sponging in the Ameri- can Miller, by the late Mr. Thoms, of Alyth. In Scotland, flour barms are largely used : the preparation of these barms has already been described. The barm constitutes the ferment, and is mixed direct into the sponge. Scotch bakers work on either the half or quarter sponge system. The following directions for sponging are quoted from Thoms’ article. 562. “ Half Sponge. — ^Sponging with either Virgin or Parisian barms is identical, whether the sponges are half or quarter. A 280 lbs. sack of flour requires over all stages of fermentation from 16 to 18 gallons of liquor. I assume here that the reader knows all about stirring a sponge. Half sponge means half of the total liquor in sponge. For every five or six parts, whether pints or gallons of liquor in half sponge, we give one ]3art of either of these barms. The temperature of the sponge liquor, of course, varies with the seasons, ranging from, in summer, 76° F. to 84° F. ; in winter, from 90° F. to 98° F. ; the sponge to rise twice, and be on the second turn within 12 hours. Also, to every gallon of liquor in sponge, when using water of ordinary softness, 2 oz. of salt, and the rest of the salt considered necessary at doughing stage. The best flour we find for sponging with these barms is American North-West ‘ Spring ’ and Russian ‘ Straight ’ grades. Observe, not ‘ Bakers,’ which means ‘ straight,’ or one-run flour, with the cream, in the shape of patent, taken out. The less winter wheat flour used in these sponges the better ; it should be used at the dough stage. Few varieties of winter wheat flour will rise twice in the sponge and produce good bread. Many of them, when sponged without admix- ture, particularly ‘ patents,’ will not rise twice with the purest barm or pressed yeast. Limited to winter wheat flour and half -sponging with tliese barms, I would sponge stiff almost half the total flour, and take the sponge on the first turn. Sponging with strong glutinous flours, such as BREAD-MAKING. 419 Hard Spring and Russian, I would use only about one-third of the total flour required in all stages ; that is, the half sponge here referred to is only a fair working stiffness/" 563. “ Quarter Sponge. — This system is found most convenient where machinery is used (the half sponging where hand labour is employed for sponging and doughing), and means J of the total liquor for a known quan- tity of flour in the first stage, instead of J as in half-sponging. Quarter- sponging is done in tubs. Sponge for one sack of flour requires a tub of 50 gallons capacity. Say we wish quarter- sponge ready for doughing at 4 a.m. to-morrow, then at 2 p.m. to-day we take — for making about one sack of flour into bread — 3 gallons water, IJ or IJ gallons barm, and 6 oz. salt, and mix these with the necessary flour into a sponge as stiff as batch dough. In 12 hours, or 2 a.m. to-morrow, the sponge will be turned, the flrst time J-inch, then we break in or up with machine or hands, the quarter with 12 gallons more water, IJ lbs. or IJ lbs. more salt, and add enough flour to form a very weak sponge. This will rise again in the tub and be on the turn in about 2 hours, or 4 a.m., when the remainder of the salt necessary is dissolved in J gallon water, and dough made. Many, and especially in cold weather, do not dissolve the salt in water, but simply sprinkle the salt over the sponge in the machine or trough. It will be observed that in neither the half nor quarter sponges is there ferment or potatoes used. The barm is the ferment, and is added direct to the sponge. For regulating fermentation in warm weather, in addition to colder water, it is advisable to reduce the quantity of barm or yeast, and in cold weather to increase it."" 564. Doughing and Baking. — In a personal communication to one of the authors, Mr. Thoms states : “ My article in the American Miller on ‘ Flour Barms and Sponging " leaves off with the sponges ready at 4 a.m. Let us suppose the sponges ‘ broken in " — the technical term — with the neces- sary salt and water, we then mix in the flour. Yes ; but what flour ? Spring American is supposed to be used in sponges, and what we will use in dough will depend on the price for the flour, the price for bread, and whether our bread is to be crusty as in England, or close packed, high volumed, and silky skinned as in Scotland. In England I might use all Winter American flour in dough, here not more than half Winter — sound red. What home grist we have goes into the dough, together with part Spring flour. Indian wheat is going largely into English grist, but I would pre- fer the Indian in sponge. I doubt the dough stage being long enough to allow the hard gluten of Indian wheat time to sufflciently hydrate and soften (peptonise) ; without which the bread would be harsh, low, dry soon, etc., etc. “ The doughs, of whatever flours composed, will be made by 4.30 or 4.40 a.m., and are allowed to lie for | hour, then turned, dry dusted, and kneaded from one end of the trough to the other and back again ; and in another | hour or so, or about 6 a.m., they are thrown out and scaled off. Wliere kneading machines are employed, the dough should have more mixing, in order to knock out proof before throwing or turning out. How do you know when it is ready to throw out and scale off ? We judge only by feel and smell. The dough should feel tight, lively, and resistant, tear easily ; and the rent, on the head being held down and a deep inspira- tion taken through the nose, should show carbon dioxide in volume nearly suffocating, accompanied by a slightly vinous odour. “ If scaling off begins at 6.0 a.m., moulding the loaves may begin at about 6.30 or 6.45. This refers to medium slack doughs for close packed bread x stiff doughs require longer. After moulding, the medium slack 420 THE TECHNOLOGY OF BREAD-MAKING. loaves are allowed from 15 to 30 minutes to prove in the boxes, and then run into the oven. Stiff dough, again, requires longer proof ; and, except in summer, the boxes holding the moulded loaves are slightly heated. “ The time in oven for 4 lb. close-packed, square loaves is 2 hours, and the best baking temperature 400° F., while the bread is baking. For 2 lb. square loaves, the same temperature, time, IJ hours ; these data refer to both steam and Glasgow ovens coke heated inside. A higher tem- perature and shorter time we find carbonises the top and bottom crusts,, while the crumb in the heart of the loaf is more or less raw. Crusty loaves, 4 lbs., slightly packed, temperature about the same or a little less, 380° to 400° F., and time, IJ hours ; 2 lb. crusty loaves, same temperature, time, 1 hour. These are not the shortest times in which the various breads can be baked, only what experience has shown me to be the best. Tho baking heats refer to the time while the breads are in the oven. If the fires are lighted at 4.0 a.m., it will, of course, be necessary to heat the ovens higher than that ; how much higher will depend on the heat of the ovens before lighting the fires. On Mondays we go higher than on other days ; the steam ovens we heat up to 480° F. ; the ovens heated with coke or coal inside we heat up to 550° F. By the time the batches are ready to go in they will have cooled down to 420-30° F., and by the time the batches are actually in they will show a temperature of 410-15° F.’' 565. Scotch Bread-making Processes, Meikle. — ^Mr. J. Meikle, of Belfast, has favoured the author with the following specially obtained information. The various data have been submitted to several experienced Scottish bakers, and therefore may be regarded as perfectly trustworthy. Scottish systems of bread-making differ a good deal from the pro- cesses that obtain in England. Sponging is almost as popular to-day as it was two decades ago ; all serious operations indeed being carried through under some kind of sponging system. The two leading processes, however, are the “ quarter ’’ and the “ half '' sponge. Quarter Sponge, for IJ Sacks of Bread. 28 lbs. Water. 10 lbs. Barm. 70 lbs. Flour. 10 oz. Salt. 80° F. Temperature. Time — 13 hours. Sponge. 160 lbs. Water. 2J lbs. Salt. 126 lbs. Flour. 78° F. Temperature. Time — 1^ hours. Dough. £0 lbs. Water. lbs. Salt. 224 lbs. Flour. 78° F. Temperature. Scale in 1 J hours : the temperatures given are those of sponge, etc., when made. The quarter system is a three process system. The quarter is made up at nigiit generally and lies about 13 hours ; it should then be up and dropped an inch, and is turned into a “ sponge tub — a tub of a capacity of 48 gallons — then water is added, the quarter is well broken, then salt and Hour are put in to make a thin sponge. The sponge lies about 75 minutes and is doughed as soon as it shows signs of setthng down : this is of course for square batched bread, and nothing can touch this system for appearance : nearly all the bread of Glasgow and the West is made in this way. BREAD-MAKING. Half Sponge, IJ Sacks. 421 100 lbs. Water. 20 lbs. Barm. 185 lbs. Flour. IJ lbs. Salt. 80° Temperature. Ready 13 hours time. Dough. 105 lbs. Water. 6J lbs. Salt. 235 lbs. Flour. 78° F. Temperature. Scale in If hours. Both this and the previous system dough want at least one turn or cut back while lying in dough. This system does not make such picture bread as the quarter, but it eats better, particularly so wFen distiller's yeast is used. This is the kind of system worked in the North of Ireland ; but the length of time the sponge lies is being consider- ably curtailed in these days. Short System. Short systems of fermentation are making some little headway in Scot- land, but probably as a novelty ; the following turns out a passable loaf when suitable flours are used. Short Process Sponge. 70 lbs. Water. 1 lb. Salt. 74 lbs. Flour. 3 lbs. Yeast. 86° F. Temperature. Time — 1 hour. Dough. 145 lbs. Water. 7 lbs. Salt. 346 lbs. Flour. 82° F. Temperature. Lie 3 hours before scaling. This process does not give the “ pile " of sponge bread, but it makes a much better square loaf than a short straight dough system does. Flour used in Scotland. The flour trade in Scotland has undergone great changes during the last fifteen years, for whereas at that time American flour was the only flour that mattered, the imports from the United States are now almost a neghgible quantity. But Scotch bakers need strong flours, or what is the same thing practically, they think they need them, and the home millers supply them. Minnesota spring wheat of good quality is of course as scarce as Min- nesota flour, and millers use strong Russians and Manitoban wheats instead. Flours from those wheats are used for sponging. For doughing a propor- tion of American Winters was at one time a favourite, and even now American Winters, or home-milled flours from Australian and Argentine wheats, blended to work like Winters, are much used, with say a proportion of Kansas flour, and some flours of the “ Millennium ” and ‘‘As You Like It ” type of English milled flours. There is a wider range of doughing flours, for the kind of flour wanted for this purpose depends upon what has been used in the sponge. The wheats of Manitoba, Kansas, Australia, Argentine, and so on, all come in useful. For barm flour fine Russian and Manitoban wheats are favourites. This flour is very often a straight run flour ; straights suit barm-making best. By the way, about the best virgin barm the writer ever saw made for a length of time was made from Scotch kiln-dried wheat milled on stones. Hungarian flour, once a prime favourite for good class bread, is now almost unknown in Scotland. (Personal Communication, October, 1910.) 422 THE TECHNOLOGY OF BREAD-MAKING. Review of Pan ary Fermentation. 566. It is proposed in the succeeding paragraphs to consider the nature of the chemical changes which occur during bread or panary (from panis^ bread) fermentation. Suggestions will also be made as to possible improve- ments in methods of carrying out the various processes, with the hope that they may lead to the avoidance of those causes which result in the pro- duction of bad or inferior bread 567. The Ferment.— Potatoes, termed by the baker “ fruit,” constitute the principal ingredient of the ferment ; their composition is indicated in the following analyses. No. 1 was grown with mineral manure. No. 2 with a rich nitrogenous manure : — No. 1. No. 2. 7640 75-20 14-91 15-58 2-17 3-60 2-34 1-29 0-15 1-11 0- 29 0-31 1- 70 1-99 0- 99 1-03 1- 00 0-90 Water Starch Proteins . . Dextrin Sugar Fat Extractive Matter Cellulose . . Ash Roughly speaking, a potato contains three quarters of its weight of water and about 15 per cent, of starch ; the remainder being made up of small percentages of proteins, dextrin, • sugar, and other substances. On being boiled, the starch is gelatinised, and on mashing the potatoes, together with the liquor in which they have been boiled, a starch paste is formed, containing also considerable quantities of dextrin and sugar, and what is of great importance, soluble nitrogenous compounds. Yeast on being sown in this medium sets up an active fermentation, ^largely due to the sugar already present, together with the strong nitrogenous stimulant. In Chapter XI it has been demonstrated that the fermen- tation is almost as active in the filtered potato water as in the mash. It must also not be forgotten that yeast alone is incapable of inducing dias- tasis in starch paste. Consequently any unaltered starch suffers little change in a ferment containing only boiled potatoes and yeast. But raw flour being also commonly added, the yeast induces a change in the flour proteins, in virtue of which they become somewhat active hydrolysing agents, and so the potato starch is indirectly converted in part into sugar. The yeast, when sown in a ferment, multiplies by growth, and thus a rela- tively smaller quantity of yeast is enabled to do the after work. A large proportion of the starch of the potato still remains unchanged at the close of the fermentation of the ferment ; so also, the nitrogenous matter of the potato in great part remains. When the ferment is added to the sponge, the smaller quantity of yeast not only does more work because of its having liad the opportunity of growth and reproduction in the ferment, but also because the nitrogenous matter of the potato still acts as a yeast stimulant in the sponge. The active effect of potato water alone shows that this stimulating action of the ferment on yeast must not be entirely ascribed to the starch present. From the active stimulating nature of the nitro- genous matter of potatoes on yeast, it seems probable that that matter consists of nitrogen in some other form than albuminous compounds. Sum- ming up these changes into one sentence, in the ferment the yeast acts on the soluble proteins of the flour and enables them to effect, to a limited extent, diastasis of the starch ; this results in the production of a saccharine medium in which the BREAD-MAKING. 423 yeast grows anil reproduces ; further, the soluble nitrogenous matter of the potato acts as an energetic yeast stimulant. It is essential that the potatoes used in the ferment be sound : they should first of all be washed absolutely clean. A common practice is to place them in a pail or tub, with water, and scrub them with an ordinary bass broom ; this treatment is inefficient, as potatoes served in this way still retain a considerable amount of dirt. The potatoes are then boiled in their jackets, and afterwards rubbed through a sieve in order to separate the skins. By far the best plan to clean potatoes is by means of a machine, of which the following type answers well for all practical purposes. The machine consists essentially of an outer tub, in which is fixed a vertical revolving brush : the potatoes are put in, and about two minutes turning the brush cleans them most effectually. The dirt is removed and also a good deal of the outer skin, while the interior of the potato remains intact. Treated in this manner the potatoes have only just the slightest film of skin to be removed, after boiling, by means of the sieve. In the next place, the pan, or other vessel used for boiling the potatoes, should be kept clean ; this is only done by its being washed, drained, and wiped dry every day. Not only the potatoes, but the water in which they are boiled, should be quite clean enough, if need be, to go into the bread. At present, many bakers steam their potatoes in preference to boiling : this modification is cleanly and convenient. The potatoes are placed in a metal work cage, which in its turn is placed in a box arrangement, through which steam is conducted from a boiler : when sufficiently cooked, the cage, together with the potatoes, is lifted out, and its contents poured on to a sieve. The ferment should be rapidly cooled to the pitching temperature of about 80° F. in summer, and 85° in winter : in summer it is very important that the baker should throughout conduct his fermentation at as low a temperature as possible. During the time that a ferment is working the temperature should be kept even : for this purpose select a place in the bake-house free from draughts or excessive heats. At present, flour, together with malt extract and a number of other materials, are being used as substitutes for potatoes in ferments, the use of which is now the exception rather than the rule. 568. Panary Fermentation. — The consideration of the division of this process into sponging and doughing may be postponed until after a study of the nature of the changes occurring during panification as a whole. Yeast flour, and water, at a suitable temperature, on being mixed so as to form a dough, immediately begin to react on each other. The flour, it must be remembered, contains sugar, starch, and both soluble and insoluble proteins. The yeast consists essentially of saccharomyces ; but bacterial life is also present in greater or less quantity, not only in the yeast but also in the flour. The yeast rapidly sets up alcoholic fermentation, thus causing the decomposition of the sugar into alcohol and carbon dioxide gas ; the latter is retained within the dough and causes its distension. Functioning in dough, no reproduction of the yeast occurs ; after a time the yeast cells disappear through the degradation and rupture of their walls. In addition, the yeast attacks the proteins present, effecting changes in them which are similar to, if not identical with, the earlier processes of digestion. Albumin and its congeners are, in fact, more or less peptonised. The gluten, from being hard and india-rubber like, becomes softer, and within certain limits more elastic ; but if fermentation be allowed to pro- ceed too far, the gluten softens still further, and its peculiar elasticity in great part disappears. It is uncertain to what extent these changes in the gluten are due to the specific action of yeast, as they also occur, 424 THE TECHNOLOGY OF BREAD-MAKING. although more slowly, in flour which has simply been mixed with water. It has been already explained that under the action of yeast the albu- minous bodies of flour acquire the power of effecting the diastasis of starch ; this compound is consequently to some extent converted into dextrin and maltose during panification. The amount of starch so hydrolysed depends largely on the soundness of the flour. In addition, the diastase of the flour itself will probably have some action in inducing starch con- version. The lower the grade of the flour, the more raw grain diastase it usually contains. When potatoes are used, whether as a ferment or as a direct addition to the flour, they furnish soluble starch, and also act as a nitrogenous yeast stimulant. While the yeast effects important changes in the albuminous compounds of flour, experiments made and described in Chapter XI show that little or no gas is evolved as a consequence of such changes. The gas produced in dough during bread-making is the result of normal alcoholic fermentation of sugar by the yeast. Summing up the changes produced in panification — they are alcoholic fermentation of the sugar, softening and proteolytic action on the proteins, and a limited diastasis of the starch by the proteins so changed. So much for the action of yeast on dough. The next point of import- ance is the effect produced by such other organisms as may be present. The principal one of these is the lactic haciUus ; under its influence the sugar of the dough is converted into lactic acid. Either the organism itself, or the acid produced by its action on sugar, has a softening and dissolving effect upon gluten. Opinions differ as to the desirability, or otherwise, of the presence of lactic ferments in yeasts used for bread-making. It has already been explained that their being found in any but the smallest quantity in brewers’ or compressed yeasts is an unfavourable sign, as they show that due care has not been taken in the manufacture of the yeast ; for that reason their presence is deemed unfavourable. In Scotch flour barms th^ presence of lactic ferments in not too great amount is deliberately encouraged ; experience having shown that if the barms be brewed so as to exclude these organisms such good bread is not produced. In Scotch bread-making very hard and stable flours are used ; the lactic ferment does good service in softening the gluten. It is possible also that during the long period of sponging and doughing, the changes induced by the lactic ferment may cause slight evolution of gas ; but so far as actual aeration of the dough is concerned this may be viewed as a negligible quantity. It must be remembered that the soupQon of slight buttermilk flavour of a valued characteristic of Scotch bread. In bread-making, as conducted by most English processes, particularly with soft flours having but little stability, there seems no useful function which the lactic ferment can per- form ; its absence is therefore rather to be desired than its presence. A yeast may contain other organisms in addition to those just mentioned ; these are capable of inducing changes of a far more serious nature than does the lactic ferment. Among these there are the organisms which cause butyric and putrefactive fermentation. That bane of the baker, sour bread, is commonly ascribed to the action of either lactic or acetic fermen- tation ; it is, however, far more probable that this unwelcome change is due to incipient putrefactive and butyric fermentation ; since the odour of a sour loaf is very different from that of either the vinegar-like smell of acetic acid or the buttermilk odour accompanying lactic acid in altered milk. The souring takes place more usually in the bread rather than in the dough. In order to produce a healthy fermentation in dough, healthy yeast is of vital importance : purity from foreign organisms is desirable (saving, perhaps, a small proportion of lactic ferment in flour barms), but above BREAD-MAKING. 425 all the yeast itself must be active and in good condition. Given a yeast, which contains a certain percentage of foreign ferments, those ferments Avill be held in abeyance while the yeast itself is energetic and healthy. Bakers are often puzzled by microscopic observations of yeast ; they find that, of two yeasts, one produces sour and the other a good bread, and yet that the two contain about the same quantities of disease ferments. They are consequently very apt to despise any conclusions they may have drawn from microscopic observations ; but the difference in such cases lies in the yeast itself : the one will be healthy the other weak and languid. Quoting again from previously described experiments, in the same sample of wort, divided into two portions, the one only of which was sown with yeast, and both equally exposed to the air, it was found that in the presence of yeast life, bacteria refused to develop, while in its absence they repro- duced with enormous rapidity. In the same way the healthy yeast sus- pends the developments of bacteria in dough, while the yeast being weak and almost inactive, bacterial life flourishes apace. Examination would reveal that in most cases of unhealthy panary fermentation the fault is as much due to the yeast itself as to the abnormal presence of foreign ferments. 569. Sponging and Doughing. — This division of the process of panary fermentation into two distinct steps is of extreme interest. The origin, and reasons which led to the adoption, of this mode of procedure are prob- ably due to the exigencies of dough-kneading by hand. For even when using flour from the lot which has been placed in his trough, the baker usually elects to work a part of it into a sponge first. The reason, or at least one reason, is that the dough softens on standing, and therefore there is less work involved in mixing in the flour in two instalments than in one, as the first lot will have got considerably softer. Further, very little experi- mental work in this direction will have shown the baker that he required to use less yeast, and got better results when working in this way. Hence, doubtless, for original reasons such as these, the division of bread-making into sponge and dough. Independently of this, they have for other reasons a most important scientific justification. The reader will by this time be familiar with the division of flours into strong and weak varieties. The various tests given in a preceding chapter show not merely that one flour absorbs more water than another to form a dough of standard stiffness, but also that some flours fall off far more rapidly in stiffness than do others when kept in the condition of dough. There are therefore two distinct properties here to be considered in relation to flour, the absolute quantity of water it absorbs, and also the rate at which slackening goes on during panification. Remembering the previous definition of water-absorbing power, the relative capacity of resistance of flours, to a falling off in water-retaining power during fermentation, may appropriately be termed their “ Stability.” As a rule, the strong flours are also the more stable, but this does not necessarily hold good in all cases. It has been already explained that, for the pro- duction of the best bread, fermentation should be allowed to proceed suffi- ciently far to soften and mellow the gluten, but no further. At stages either earlier or later than this, the bread will lack both in appearance and flavour. It is therefore necessary to so regulate fermentation as to stop at precisely this point ; unfortunately no exact means are at present known whereby it can be determined with precision. The more stable a flour is, the longer it requires to be fermented before this point is reached, hence where flours of different qualities are being used, the more stable should be set fermenting earlier than the others. In this lies the reason for using some flours at the sponge and others at the dough stage. Flours from hard wheats, such as Spring American or Russian, should be used 426 THE TECHNOLOGY OF BREAD-MAKING. in the sponge ; and American Winter or English wheaten flours in the dough. Working with stable flours in the sponge, experience has shown according at least to the London practice, that the best results are ob- tained by allowing the sponge to rise and fall once, and then to rise again. The time taken for this rising and falling is found to agree with that neces- sary for the sufficient mellowing of the gluten. This empirical test, which is the result of careful watching and experience, is at present the baker’s principal guide in determining the progress of fermentation. It affords evidence of the degree of rapidity with which gas is being evolved, and indirectly of the extent to which the other chemical changes have proceeded. Reference has already been made to the great change which has during the past few years come on baker’s practice. For various reasons, among which those cited by Callard are some of the leading ones, the sponge and dough methods have largely given place to straight or off-hand doughs. Possibly the exigencies of hand kneading, referred to at the commence- ment of this paragraph, have so completely disappeared, with the greater adoption of machinery, by which a stiff straight dough is readily made, that any division of the dough-making process is no longer found or deemed necessary. 570. Variety and Quantity of Yeast used. — The variety of yeast employed produces a marked effect on the charaeter of the resultant bread. Good brewers’ yeast is almost universally admitted to induce a characteristic- sweet or “ nutty ” flavour, hence it has been largely used in the manufacture of so-called farmhouse bread. Colour in this variety of bread is seeondary to sweetness of flavour. While brewers’ yeast has a somewhat energetic diastatic action on the proteins and starch of dough, its fermentative power is comparatively low in that medium. Undoubtedly, one of the reasons which has led to the comparatively extensive use of potatoes in bread- making is their stimulant action on the gas-producing power of brewers’ yeast in dough. Continental compressed yeasts, on the other hand, are marked by their rapid power of inducing alcoholic fermentation in dough : experience indicates that neither potato nor flour ferments are necessary, at least as stimulants, when working with these yeasts. Motives of economy on the part of the bakers, and competition on the side of the yeast merchants, both lead to a certain rivalry among the latter as to whose yeast is able, weight for weight, to adequately ferment the greatest quantity of flour. Now, while it is important that the baker should know with accuracy the relative strengths of different brands of yeast, it is nevertheless not wise to be too sparing in the quantity employed to a sack of flour. First, select the strongest and purest yeast you can get for the money, and then don’t be afraid to use sufficient of it. This advice should have especial weight where soft, weak flours, having comparatively little stability, are so largely employed. Flours of this kind will not bear being kept so long in the sponge and dough stage as is necessary to ferment them with a very small quantity of yeast ; they, if so treated, produce sodden, heavy, and sometimes sour loaves ; when any saving in yeast is more than compensated by a less yield of bread. 571. Management of Sponging and Doughing. — In order to insure success in the manufacture of bread, sound materials are the first requisite : after that the most important in this, like all other operations in which fermenta- tion employs an important part, is the proper regulation of temperature. Tiie yeast should always be stored where it will get neither too hot nor too cold ; for extremes of temperature in either direction weaken the action of yeast. Brewers’ yeast in particular suffers from this in summer weather ; BREAD-MAKING. 427 and so, many bakers who use it in the winter change over to compressed yeast in the summer. In summer time the compressed yeasts are when fresh more active than in winter : in the latter season, the strength of the yeast may be increased by allowing it to stand for a time in water at 85° F. before being used. A still better plan is to stir a small quantity of sugar or malt extract into a bowl of water and then add the yeast ; let this stand for about an hour, gently stirring now and then in order to aerate the liquor. Such treatment refreshes and invigorates the yeast, and so enables it to afterwards work more actively. Both sponge and dough, or straight dough, should be so managed as to keep the temperature as nearly constant as possible during the whole of the fermentation. Good yeast works well at from 80° to 85° F., and at that temperature lactic and butyric fermentation proceed but slowly, even in the presence of the special organisms which induce these types of fermentation. Sudden cold should also be avoided, as a chill to working yeast is most detrimental, causing fermentation to entirely cease, or at the best to proceed most sluggishly. Such a sudden lowering of temperature may indirectly be the means of producing a sour loaf. 572. Use of Salt. — ^A great deal has been written as to the use of salt as a guiding agent in fermentation ; so far as the yeast is concerned, salt is generally viewed as having a retarding influence ; although the opinion has been expressed that quantities of salt under 3 per cent, of the water used stimulates the action of yeast. This opinion is based on certain obser- vations of Liebig. The author's own experiments {vide Chapter XI., para- graph 371) lead him to conclude that salt, in all proportions from 1*4 per cent, upwards, retards alcoholic fermentation, and diminishes the speed of gas evolution. Salt acts still more powerfully as a retarding agent on lactic and other foreign ferments, and so aids in the prevention of unhealthy fer- mentation. In addition, salt also checks diastasis, and thereby prevents undue hydrolysis of the starch of the flour. In summer time, or when any suspicion of instability attaches to the flour, it is well to add some portion of the salt to the sponge ; but when the flour is good, and the yeast pure and healthy, the whole of the salt may be deferred to the dough stage. In the Scotch methods of bread-making, flours of a very strong and stable character are used in the sponge, which altogether is allowed to stand about 12 hours. A slight amount of lactic acidity is developed in this, and is viewed as normal ; it has an important function in softening and mellowing the gluten. It will be noticed that a small proportion of salt is, in the Scotch process, added to the sponge. 573. Loss during Fermentation. — This has been variously estimated, among the highest figures being that of Dauglish, who expressed the opinion that this loss amounted to from 3 to 6 per cent. In order to determine the maximum amount of loss possible, the authors made a direct experi- ment — 100 parts by weight of soft flour from English wheats were made into a dough with distilled water, two parts of pressed yeast being added ; no salt being used. This dough was allowed to stand for from 8 to 9 hours at a temperature of about 85° to 90° F. ; fermentation proceeded violently, but towards the end of the time had apparently ceased. The dough was then placed in a hot-water oven, and maintained at a constant temperature of 212° F. for 10 days ; the same weight of flour and yeast, but no water, was also placed in the oven. At the end of that time the fermented dough was found to have lost 2*5 per cent, compared with the flour. Now in this extreme case a soft flour was used with distilled water and no salt, and about six times the normal amount of yeast ; the temperature was pur- 428 THE TECHNOLOGY OF BREAD-MAKING. posely maintained at a high point, and the fermentation carried on so long as any decided evolution of gas occurred. Yet, under these conditions, which far and away exceed in severity any such as are met with in practice, the loss was less than Dauglish’s minimum estimate. In the fermentation experiments described in Chapter XV., paragraph 466, the total loss in weight of the dough during fermentation was only 0*59 per cent with a strong flour, and 0 *70 per cent, with a weak flour. In both cases the extent of fermentation was as nearly as possible that normally employed in modern bread-making processes. 574. Baking. — For baking, the oven should be at a temperature of 450- 500° F. Most modern ovens are now fitted wath a pyrometer, by means of which the temperature may be read off. If depending on this instru- ment, care must be taken that it is in efficient working order. In the oven the dough rapidly swells from the expansion of the gases within the loaf by the heat. Its outside is converted into a crust ; the starch being changed into gum and sugar : these are at the high temperature slightly caramel- ised, and so give the crust its characteristic colour. The effect of the heat on the interior of each loaf is to evaporate a portion of the water present in the dough : the carbon dioxide, and a portion of the alcohol produced by fermentation, escape with the steam^ and may be recovered from the gases within the oven. While any water is present in the bread, the tem- perature of its interior can never rise above the boiling point of that liquid. Owing to the pressure caused by the confining action of the crust, that boiling point may, however, be somew'hat higher than under normal atmos- pheric pressure. The increase due from this cause is probably not more than some two or three degrees. As baked bread still contains some 35 to 40 per cent, of moisture, it may be safely stated that the inside of the loaf never rises to a higher temperature than 215° F. It is commonly stated that, in the act of baking, the starch of flour is gelatinised. This, however, is only partly the case. The temperature of a baked loaf rises considerably above that requisite for gelatinisation, but there is also another condition necessary. Gelatinisation is essentially an act of union with w^ater, and a loaf does not contain sufficient moisture to anything like gelatinise the whole of the starch. At the moment of writing, a fragment of bread has just been examined microscopically, and field after field is seen of unbroken and apparently unaltered starch corpuscles. One of the largest present w^as measured and found to be 0*057 m.m. in diameter, showing that the starch had not even materially swollen. Doubtless under the influence of heat the starch has become softened, but the larger proportion of the granules still remain intact. (Compare paragraph 171, page 81.) At the temperature of I the interior of the loaf, the coagulable proteins Avill have been coagulated, and their diastatic power entirely destroyed. The com- position of bread, compared with that of flour, is dealt with subsequently. 575. Time necessary for Baking. — ^The time during wLich bread is kept in the oven varies considerably in different parts of the country ; much must depend on the temperature — whether the oven be quick or slack. For 4 lb. crusty loaves an hour to an hour and a quarter seems to be an average time. The half-quartern or 2 lb. loaf is a much commoner size in England, and loaves of this description can readily be baked in from 40 to 50 minutes in any w-ell constructed oven. 576. Glazing. — ^The admission of steam to an oven, w hen properly man- aged, has the effect of producing a glazed surface on the outside of the crust : this operation is familiar to bakers as that by which Vienna rolls are glazed. In order that the operation shall be effective, the bread or rolls should be BREAD-MAKING. 429 as cool as possible. The steam should be simply at atmospheric pressure, and saturated with moisture. At the instant of the cool loaf entering the steam atmosphere of the oven, a momentary condensation of steam occurs over the whole surface, which is thus covered with a film of water at the boiling point. This renders the starch of the outside surface soluble, and as the w ater dries off leaves a glaze of soluble starch, part of w hich possibly has been converted into dextrin. The injection of steam into the oven not only helps to dextrinise and glaze the crust, but also serves the purpose of keeping the interior of the loaf moist by preventing too rapid evapora- tion. 577. “ Solid ” and “ Flash ” Heats. — These terms are frequently used fey the baker in speaking of the character of the heat of different ovens. The former is applied to heat which is continuous, the latter to heat which is very temporary, but frequently for the moment intense. It wull be found that the so-called “ solid "" heat is usually evolved from the walls of a w^ell heated oven. A good oven should have plenty of material about it ; this gets hot through, and afterw^ards radiates heat slowdy but continuously. If the oven walls be too thin they cool too quickly ; in consequence they have to be heated very intensely at the start ; the result is that the oven at first burns the bread, and towards the end has not heat enough to com- plete the baking of the batch. With thicker walls the initial temperature of the oven need not be so high ; the fall in temperature taking place more slowdy, the oven still retains a good heat at the close of the baking. The heat which reaches the bread from the w^alls of the oven is largely in the form knowm as “ radiant heat ; it is continuous, and need not be of abnormally high temperature in order to thoroughly and efficiently bake bread. The consequence is that the interior of the bread is w ell baked, while the crust is not burned. A “ flash "" heat, on the other hand, is produced by the contact of highly heated gases with the bread. Certain varieties of ovens are fired by the introduction of flame into the oven itself. Such introduction of flame should be employed to previously raise the temperature of the oven, not, if used at all, to bake the bread itself. The reason is obvious ; it is exceed- ingly difficult to regulate the temperature of a current of hot air from a flame with great exactitude. The temperature is sufficiently high at one time to burn the crust ; at another so low as to prevent, during the time the bread is in the oven, its inside being sufficiently cooked. Further, if the bread is to be heated by the hot air resulting from the direct admission of flame into the oven, there must necessarily be also some means of exit for the gases from the flame. The hot air from a furnace cannot, in fact, be drawn into the oven without some means for their after escape. The result is that these gases carry with them the steam evolved from the baking loaves, and so subject the bread to a dry, instead of a steam saturated, atmosphere. 578. Cooling of Bread. — The loaves on being taken from the oven should be cooled as rapidly as possible in a pure atmosphere ; for this purpose, wiiere practicable, open-air cooling sheds should be provided. Failing these, the cooling-room must be w'ell ventilated. It goes without saying that the cooling loaves must be adequately protected from rain. 579. Summary of Conditions affecting Speed of Fermentation. — Where fermentation starts with the first addition of yeast to the other materials, it does not conclude till the bread has been for some time in the oven, and possibly not even then. At this stage of w^ork, with both principles and details of methods of working explained, a bird's-eye view of the whole course of fermentation should be of service. 430 THE TECHNOLOGY OF BREAD-MAKING. A ferment, when used, is a means of making yeast by a process of repro- duction from that originally added. Steps are taken at the same time to ensure vigour in the new yeast formed. The speed of fermentation of the ferment is hastened by increase of temperature, but beyond a certain point that of acid-producing organisms is also more than proportionately stimulated. Aeration during fermentation tends to increase the vigour of the produced yeast. (Compare Adrian Brown on the action of oxygen on fermentation, page 162). Assuming a start has been made with either sponge or off-hand dough, the same laws govern fermentation. First, let us see what conditions accelerate fermentation. With regard to yeast, the greater the quantity, the more quickly it pro- ceeds : with sound yeast there is no fear of imparting a yeasty taste to bread with many times more than necessary for ordinary bread- making. The strength of the yeast will also directly tend to increase the rate at which fer- mentation proceeds. Flour. — Soft flours tend to hasten fermentation ; they contain more sugar and more starch in a condition susceptible to diastasis. Their pro- tein matter is more likely to act as a yeast stimulant, while the softness of the gluten lessens a physical obstacle to rapid action of yeast. Potatoes, Saccharine Extracts. — These act as stimulants, and tend to increase the speed of fermentation. Water. — The principal way in which this acts is in virtue of the propor- tionate quantity used. When doughs are slack, fermentation proceeds much more rapidly. Aeration. — Flour well aerated is likely to work more rapidly, especially in slack sponges. Notice how in Vienna bread and batter sponge is beaten and worked, and how much more vigorous and “ lively ” it is in consequence. Temperature. — This governs all ; with low temperatures yeast works very slowly, if at all, and with higher temperatures fermentation is accelerated. Next, as to conditions retarding fermentation : these may be summed up as the opposite of the accelerating agents — yeast, weak or in small quan- tities ; hard, dry flours ; stiff, unaerated doughs ; low temperature ; and finally, the addition of salt, which has a very marked retarding effect. By modifying one or more of these conditions, the baker is able to regu- late the speed of his fermentation ; and, where certain of them are altered by causes beyond his control, is able to more or less compensate the disturb- ance by introducing changes in one or more of the others. Suppose, for example, the working of a sponge is unduly hastened by having to use a softer flour than usual, this may be modified by making it tighter, or working with less yeast, or at a lower temperature. A good deal of the art of the baker consists in properly adjusting these variable factors so that they shall properly balance each other, and all conduce to the production of a good loaf of bread. 580. Quick versus Slow Fermentation. — This is probably a convenient place to make some reference to the relative merits of quick as against slow fermentation processes. One fact revealed by the record of modern methods given in paragraph 539 is that as a whole the various operations of baking have been materially shortened during the past few years. Reference is made in a subsequent paragraph, No. 584, to some experiments on the com- parative effect on acidity production of working at comparatively high and low temperatures. The lesson taught by these experiments is that for the same amount of alcoholic fermentation a comparatively high temperature is at least not more productive of acidity than a much lower one. These BREAD-MAKING. 431 tests were taken as the starting point of an investigation by one of the authors into the broader question of the effect of speed on bread-making processes generally. The results, of which the following is a resume, were published in 1897. The various baking tests were made by Mr. Ellis, an experienced baker, who was then a student in the authors’ laboratory. A London “ whites ” flour was taken and worked throughout by means of ferment and dough method. All the water and sufflcient of the flour were taken to form a batter ferment, the remainder of the flour being used in the dough. Quantities in Grams. 1 . 2 . 3 . 4 Flour . 560 . . 560 . , . 560 560 Water . 320 . . 320 . . 320 . . 320 Yeast 5 5 . 5 15 Salt 6 6 . 6 6 Temperature of water . .70° F. 00 o o .85° F. . .115° F. Time taken to oven .13 hrs. . .lOJ hrs.. . 10 hrs. . . 3 hrs, (Note, 560 grams are about equal to 20 ounces. If these quantities throughout be halved they give in every case lbs. to the sack of 280 lbs.) Remarks on Working. No. 1. Ferment started at 8.0 a.m., well risen by 12.35, dropped 4.20 p.m., dough made 4.35, ripest at 7.10, handed up 8.5, least spring. When baked was closer in pile, good colour crumb, few small holes, not quite equal in sheen to No. 4 ; crust thin, rather dull in colour. No. 2. Ferment started at 10.20 a.m., dropped 5.0 p.m., doughed 5.5, handed up 8.20, fairly springy. When baked, was best loaf of those slow worked. Good pile and colour, crumb better texture than others. Nice coloured crust, good appearance, and best shaped. No. 3. Ferment started 10.35, dropped 4.15, doughed 4.30, handed up 8.10, moulded well, fairly springy, good colour crumb, fair sheen, very sweet to smell and taste, not quite so good a texture or appearance in crust as others. No. 4. Ferment started at 10.0 a.m., dropped at 11.30, made up 11.37, skin just cracking 12.32 when handed up, moulded 12.50. Much the boldest and best when baked, good pile, good crumb, few small holes, rather best sheen, not quite so sweet to smell, but nicer flavour to palate than No. 1. Crust thin and good colour, although well baked. In the table on page 432 the working character and keeping qualities are summarised. Percentages are also given of acid reckoned as lactic acid, sugar reckoned as maltose, and soluble matter in the breads. The general conclusions to be drawn from this series of experiments is in favour of the quick fermentation method. It is somewhat curious to And that the long fermentation loaf dried off the quicker, especially as there is a somewhat widespread opinion that short fermentation bread loses its moisture the more rapidly. In the next place experiments were made with larger quantities ; straight doughs being employed, in order to determine the minimum of time in which they could be satisfactorily fermented. The following are particulars of quantities and temperatures : — 1 . 2 . 3 . 4 . 280 lbs. of flour at 72° F. 70° F. 68° F. 70° F Water at 85° F. 95° F. 112° F 105 F. Yeast 20 oz. 19 oz. 18 oz. 22 oz. Salt 3 lbs. 3 lbs. 3 lbs. 3 lbs, Temperature of dough when made 91° F. 432 THE TECHNOLOGY OF BHEAD-MAKING. No. Character in Working. Keeping Quality and Flavour. I Sweetness. Acidity. Maltose Soluble Matter. 1 Very little spring, dead to handle all the way through. 1st. day — Slightly drier than No. 4. Not so good flavour. 4th. day — Considerably the driest when cut. 6th. day — Much the driest. ! " ! Smells sweet. 0-18 0-32 6-04 2 1 1 i F airly springy, moulded well. 1 1st. day — Rather moister than 1 or 4, and better flavour. 4th. day — Keeps its moist- ness. 6th, day — Has not kept its moistness as well as No. 4 for the longer time. Sweetest to smell and taste. 0-20 0-35 4-28 3 Rather more springy than No. 2, but not so good as No. 4, handled well. 1st. day — The moistest. 4th. day — Kept much moister. 6th. day — About as moist as No. 4. Sweeter in flavour. Very sweet, 0-18 0-28 5-68 4 Handled well ; full of spring. 1st. day — Rather moister than No. 1. 4th. day — Much the moistest. 6th. day — Moistest and good flavour. The 'pleasantest flavour of all. Does not smell so sweet. 019 OdO 5-28 Remarks on Working. No. 1 was taken 5 hours after being made, and set in oven in another 50 minutes. Loaf of good appearance and very sweet. Dough might have been taken half-an-hour sooner without injury. No. 2. Taken 3J hours after making, and set in oven in another 50 minutes. Good bold loaf, no foxiness, very sweet. No. 3. Made 2 quarts of water slacker than No. 2. Fifteen pounds of flour were reserved and dusted in when the dough was cut back at the end of 2 hours. Taken 3 hours after making. Loaf small and runny, pro- bably rather more time required. No. 4. Taken at end of 3 hours, in oven in 3| hours. Bread small and rather flat. A repeat was next made of No. 2, with the result that the loaf was in every way satisfactory and compared favourably with bread made from tlie same flour by a long system of fermentation. The whole of these were fairly stiff doughs for crusty cottage bread, probably the same degree of stiffness as is employed in London for bread of this kind. It was found that a working time of 3J to 3| hours was the best to employ, as when an effort was made to get down to 3 hours the bread fell off in quality. Endeavours were made to shorten the time, both by raising the temperature and increasing the yeast, but the results in neither case could be considered encouraging. No doubt with slacker doughs such as are made for tinned bread, the time might still further be shortened. The BREAD-MAKING. 433 flour used was a bard mixture and required to be fermented sufficiently to be free working, and not yield a pinched loaf. Softer flour again would work through in less time. The conclusions drawn were that in appearance and general character at least as good a loaf can be obtained by quick as by slow fermentation processes. The subsequent adoption of quick processes by so large a proportion of bakers is an ample justification of the forecast of 1887. 581. Summary of Course of Fermentation. — A very useful lesson may be learned by making a batch, say of 20 lbs. of flour, into a slack dough, with a full allowance of distillers' yeast, say 3 ounces ; salt and water in pro- portion, and working the batch fairly warm. Let a piece be cut off and moulded into a loaf immediately the dough is made, and at once baked — the result vill be a close, small, very moist loaf, not much bigger than the piece of dough cut off. Next bake a similar loaf from the same piece of dough at the end of every hour from the time of starting, keeping the main mass covered, and in a warm place. An instructive series of changes will be ob- served in the successive loaves. In boldness the bread improves for some hours, then remains stationary, and finally becomes “ runny " and flat. The colour of the crust is at first “ foxy,” then of a golden yellow or brown tint, and finally abnormally pale. The crumb during the first three or four loaves of the series gradually improves, and becomes more bloomy, then changes to a greyish white, losing the bloom, and then “ saddens ” and darkens, becoming a dull, cold grey, merging ultimately into a brown. At the same time it becomes ragged on the outside edges, and dark where a soft crust has been produced by two loaves being in contact with each other in the oven. In flavour, the first loaf will be sweet, but “ raw ” and “ wheaty,” characters which will be lost as fermentation proceeds ; at its best the raw taste mil have gone, leaving only a sweet clean-palate flavour. This will be succeeded by a gradual disappearance of the sweetness, the bread being neutral and tasteless : at the same time the loaf will have lost its moisture, and will be harsh and crumbly. As fermentation is pushed still further, the bread commences to be “ yeasty ” (to taste of the yeast) ; but this depends somewhat on the original soundness or otherwise of the yeast. This condition merges into one of slight sourness, first of pure lactic acid flavour, accompanied by buttermilk odour ; but gradually becoming worse, until, finally, not only is the taste offensive, but so also is the smell, partaking not only of sourness in character, but also of incipient putrefaction and decomposition. During these latter stages the bread again becomes soft and clammy. The first drying off, until the bread reaches the harsh stage, is due to the disappearance of soluble starch and dextrin by diastasis into sugar, and then fermentation : the subsequent clamminess is the result of degradation, not only of a portion of the starch, but also the insoluble proteins of the dough. Such are, in brief, the changes observable in dough under ordinary conditions of working, from the first start of fermentation to the com- mencement actually of putrefaction. These may be slightly modified by character of the flour and other constituents of the dough ; but if the con- ditions of fermentation be healthy and normal, the whole series of changes substantially follows the order given here. Changes in temperature, degree of stiffness of doughs, etc., within recognised and approved limits, may accelerate or retard fermentation as a whole, but they do not alter its character and general course. Sour Bread. 582. Souring of Bread. — ^When dough has been allowed to overwork a 434 THE TECHNOLOGY OF BREAD-MAKING. frequent consequence is that the resultant bread is sour. Among the earlier views of the causes of such sourness was that which regarded it as being due to the oxidation of alcohol. A fully worked sponge or dough contains considerable quantities of that substance, and it was argued that the well- known change of alcohol into acetic acid by oxidation, C2H5HO + 02=: HC2H3O2 + H2O, Alcohol. Oxygen. Acetic Acid. Water. was the cause of the acidity of sour bread, especially from overwrought sponges or doughs. It will be convenient at this early stage to differentiate between ‘‘ acid- ity "" and “ sour bread,"" using each of these terms in their generally accepted sense. “ Acidity "" is a chemists" term and is caused by the presence of free acid ; the measure of acidity is the amount of alkali of definite strength required to produce neutrality. “ Sour bread "’ is a baker "s term, and is applied to bread which has a sour odour and flavour to the organs of smell and taste respectively. Experiments show that acidity, as measured by chemical means, and sourness, as judged in bread by the nose and palate, are not necessarily alike in intensity or entirely dependent on each other : for this reason the limitation of the sense in which the authors personally use each term is here indicated. As opposed to what may be called the acetic acid hypothesis, it must be remembered that yeast has a great avidity for oxygen, and according to Pasteur"s view alcoholic fermentation was a starvation phenomenon in the absence of oxygen. This theory is no longer tenable, but in any case the fact remains that yeast readily absorbs oxygen from any fluid in which it is actively at work. As the acidity of a sponge or dough is the effect of acid fermentation following the normal alcoholic, there cannot be within the mass of dough any oxygen by which the alcohol disseminated through it can be oxidised to acetic acid. For this reason, therefore, it is only on the surface of the dough exposed to air that such action is possible. And even here it must be exceedingly superficial, for in the presence of the possibly slow, but continuous, exhalation of gas from the sponge, it is very improbable that any perceptible absorption of oxygen is occurring. Even when quiescent, it must be remembered that a sponge contains an abun- dance of yeast ready to start again in active fermentation as soon as supplied with food. There will therefore be on the surface of such a sponge yeast in far greater plenty than acetic acid germs, and with the greater vigour of the former organism, it is a fair assumption that of the very limited amount of surface assimilation of oxygen, the lion"s share will be taken by the yeast and converted into carbon dioxide. As both lactic and butyric acids are products of anaerobic ferments, and are the result of chemical changes which are absolutely independent of external free oxygen, the same objec- tions do not apply to these as sources of acidity. For these very cogent a 'priori reasons, the authors have viewed the presence of acetic acid as being (under any normal conditions such as are commonly found in a bakery) an exceedingly limited and practically negligible cause of acidity. 583. Sour Bread, Briant.— Briant has contributed a number of impor- tant papers to this subject and gives the following results of analysis of samples of dough by Duclaux"s method of fractional distillation : — “ I should mention that the yeast used w^as in each that of the Delft Com- pany, a brand which may be regarded as practically free from bacteria. This point is one of much importance, as will be seen when in the second section of this paper w^e consider the causes of the production of these acids. “It is well also to bear in mind that lactic acid does not, weight for weight, correspond to the same acidity as acetic acid. Three parts by BREAD-MAKING. 435 weight of acid. ‘A.’ lactic acid have the same acidity as two parts by weight of acetic (Fresh dough )- Lactic Acid Acetic Acid Butyric Acid B.^— C.’ ‘D.' ‘F.^- G.^ Lactic Acid Acetic Acid Butyric Acid (Very acid dough)- Lactic Acid Acetic Acid Butyric Acid (Same dough kept Lactic Acid Acetic Acid Butyric Acid Lactic Acid Acetic Acid Butyric Acid Lactic Acid Acetic Acid (The same dough Lactic Acid Acetic Acid Butyric Acid (about) another day)- •024 per cent. •038 None. •405 per cent. •150 •06 •622 per cent. •245 Trace. •742 per cent. •249 „ Distinct trace. •493 per cent. •175 „ Trace. •460 per cent. . . -197 kept three days longer, then extremely acid)- D08 per cent. . . -231 „ Heavy trace. “ The above results clearly show that the bulk of the acidity in acid bread is due to lactic acid, but that a certain proportion, varying from one- third to one-fifth, consists of acetic acid, and that in most of the samples the amount of butyric acid is very small. The samples in which I have found butyric acid have been made in most cases from inferio flour and bad yeast, and the connection between these and butyric acid is very close, as I shall be able to show in my next article on the subject. I believe, on the strength of the above figures, that I may claim to have proved what are the acids present in flour, for I have separated the acids by recognised methods in a fair number of samples. It is the acetic acid which, together with butyric acid (if present), gives the smell to sour dough — lactic itself being non-volatile has no smell — therefore, were dough acid with lactic acid alone, it would have no sour smell, although, of course, it would taste acid.’" Briant then remarks that “ practical experience has shown that sour bread is obtained most readily with bad yeast, common^ flour, and when high temperatures are employed, whilst the same result is favoured by over-fermentation, a slack dough, dirty yeast troughs, and over-exposure to the air during the doughing stages. Any satisfactory solution should be able to explain why it is in practice that the conditions which I have named favour the production of sour bread.” By systematic bacteriological investigation, Briant found micro-organ- isms ; and in sour dough identified lactic and acetic ferments, and in some cases, also the butyric ferment. Oh inhibiting bacterial action by the addition of chloroform, dough is absolutely prevented going acid. The conclusion is therefore drawn that acidity is due to bacterial action. The 436 THE TECHNOLOGY OF BREAD-MAKING. next point for consideration was the source of these bacteria, which were searched for among the following — water, air, yeast, dirty vessels, and flour. Practically, the results were negative with w^ater and air. It was found just as easy to get sour bread with sterilised water as with an ordinary town supply. So, too, exposure to ordinary air containing micro-organisms did not produce any appreciable difference in the acidity of dough from that produced by sterihsed air. Many modern yeasts are practically bacteria-free, and while an impure yeast may cause sour bread, yet Briant produced sour dough with a pure yeast-culture from a single cell. Whilst yeast therefore may cause sour bread, it is at any rate not the only cause for it. Dirty vessels, it almost goes without saying, are a most fruitful source of acidity. Briant found flour itself to be a most potent factor in producing acidity. Thus, he remarks that “ until I had examined a considerable number of flours, I did not realise fully how important an influence they must have upon the soundness of bread. But having made bacteriological examina- tions of a large number of samples, I am led to the conclusion that it is here that we meet with a very decided cause of sourness in bread. The differ- ences between flours in this respect are very great, indeed some are com- paratively — although none are absolutely — free from bacteria, but others contain very large quantities, and amongst them it is possible to very readily separate the lactic and the acetic ferment. In every case of sour dough, I have found the flour to contain acid-producing ferments. In a low-class flour, which in practice was found to very readily yield sour bread, unless worked with much care, we And in the flour itself precisely those ferments which are afterwards found in the dough and act as acid producers, and here we have the real cause of the acidity. Where the flour used by a baker contains any but a very small proportion of bacteria, there will always be a certain risk of acidity. By careful working the baker may reduce this risk, and particularly if he uses a commercially pure yeast and observes scrupulous cleanliness. He may find it perfectly pos- sible to produce bread which is quite sound, despite the fact that the flour contains many bacteria. For several considerations bear upon the growth of these bacteria. First is that of temperature. The activity of the lactic ferment, according to De Bary, increases as the temperature rises, up to a certain point. It grows and produces acidity comparatively slowly at a temperature of 60°, but at temperatures exceeding 70° it becomes extremely active. It reaches its maximum of activity at about 108°, above which temperature it rapidly declines in power. The acetic ferment reaches its maximum at a temperature between 85° and 93°, at which latter tem- perature its power of reproduction and acidification is enormously rapid. From these considerations it is therefore at once apparent that whilst high temperatures for panary fermentation are in all cases undesirable^ yet in cases where low-class flours are used, they are almost fatal. In low- class flours also there is almost invariably present a large excess of objec- tionable nitrogenous bodies. These bodies are particularly suitable as a nidus upon which the bacteria caja^eed, so that in low-class flour we have ^hese additional causes of risk, regain, another very important circum- stance which contributes to sour oread is over-fermentation, and the cause of this is very simple. So long as the yeast is vigorously working,, so long are the bacteria kept in check, and just as in the fermentation of wort in a brewery, we find that though bacteria are present, yet the wort itself remains free from acid until the yeast has ceased its work, so in baking the bacteria are held in check whilst the fermentation is vigorous. Imme- diately, however, the fermentation flags, the bacteria commence to act, and this is particularly the case with the acetiC' ferment, which at this BREAD-MAKING. 437 stage is supplied with the alcohol which it converts through aldehyde into acetic acid. , In fact, whilst it is possible for some small quantity of "lactic acid to be produced concurrently with the procedure of fermentation by the yeast, this is practically impossible in the case of the acetic ferment, which will only commence to act after the yeast has finished its work. But in order that the acetic ferment may convert the alcohol into acetic acid, it requires the presence of some oxygen. Therefore it is, that the more a dough is kept free from exposure to air, the less chance of production of acetic acid there is, and the practical experience of the baker has led him to adopt what is ^practically accurate from a scientific point of view, viz., the exclusion of air so far as is possible during the fermentation pro- cess. Again, the production of acidity is far more rapid if the dough is slack. When this is the case, the bacteria are able to thrive far more rapidly and vigorously than is the case with a stiff dough, and in some experiments which I have made as to the speed of souring of a stiff versus slack dough, I have found a remarkably increased rapidity of souring with the latter, and there can be no question but that, from the point of view of soundness of bread, the dough should be kept as stiff as is practicable. “ Finally, therefore, I may summarise my conclusions as follows : — “I. The acids of sour bread are acetic and lactic acids, with occasional small quantities of butyric acid. Lactic acid in most cases is present to the extent of two or three times that of the acetic acid. “ 2. The acid is produced by bacteria to be found in the dough. 3. These bacteria may be introduced by the yeast, by the use of dirty vessels, and by the flour, but their presence in the flour is the most general cause of acidity. Some high-class flours contain very few bacteria ; low- class flours are often simply teeming Avith them. “ 4. The use of high temperatures facilitates the activity of the bacteria which may be present, and is therefore objectionable. “ 5. The bacteria are present, but do not to any large extent become active until the alcoholic fermentation commences to flag. Hence, over- proved dough is specially liable to acidity. “ 6. Slackness of dough contributes to the activity of bacteria, and therefore is undesirable. 7.. Exposure to air, by supplying the acetic ferment with oxygen, favours its activity, and therefore fermenting dough should be kept as much out of contact with air as is possible.” Briant’s papers represented a most important piece of work on the Subject of sour bread, and embodied some most valuable conclusions, the principal among these being the establishment of the connection between bacteria present in dough and its acidity, and the further emphasising of the fact that a most fruitful source of acidity is the presence of bactleria in flour. (Compare with the paragraph on the comparative bacterioogical ; purity of flours in Chapter XXI.) It had long been known to bakers that, Avorking under precisely the same conditions, sourness is far more likely to occur in “ seconds ” than in “ best ” bread, but this particular reason — the greater prevalence of bacteria in low-grade flours — had here for the first time its due importance ascribed to it. 584. Personal Researches. — The authors have devoted much attention, both in the bakery and also the laboratory, to this problem of sour bread. As a result, they find themselves unable to agree Avith some of the foregoing opinions, and in the folloAving paragraphs endeavour to explain the reasons for their inability to agree Avith the same. The first point is the promulgation of the vieAV that acetic acid is so largely found in sour dough. As already explained, there are very cogent 438 THE TECHNOLOGY OF BREAD-MAKING. a priori reasons for the improbability of any great amount of acetic acid being found in panary fermentation ; and Briant recognises that acetous fermentation must be an after fermentation, “ which will only commence to act after the yeast has finished its work.'’ On examination of Briant's analytic results, one is at once confronted with the fact that in fresh dough, sample A, there is a higher proportion of acetic acid than in any of the others. Analyses C and D are of the same sample, made at an interval of a day : during this time the lactic acid has materially increased, while the acetic acid remains stationary.' Analyses F and G are also made on the same dough, but with a three days" interval ; the lactic acid has increased from 0*464 to 1*08, or to 2*35 times its original quantity. The acetic acid has similarly risen from 0*197 to 0*231, and is 1*17 times its original quantity. Although acetic acid is undoubtedly the result of an after fermentation, yet a relatively higher proportion is found in fresh than in stale doughs ; in these experiments almost the whole of the after developed acidity is due to lactic, and not acetic, acid. Following is an account of an independent series of experiments, made with the view of investigating the causes of souring of bread. Some of this w^ork was done prior to the publication of Briant’s researches, and a portion of the remainder was suggested by the results of his researches. The determinations of the different acids were made by various processes described in Chapter XXVIII., including the application of the method of Duclaux. As a preliminary to the analyses, various tests were made on the methods themselves. It is obvious that the separation of lactic from acetic and butyric acids by the process of distillation is only trustwwthy on the assump- tion that, under the conditions of the estimation, lactic acid is non-volatile. But in Miller’s Elements of Chemistry [Armstrong A; Groves), it is stated that “ on distilling an aqueous solution of lactic acid, a certain amount of acid volatilises with the steam." In order to investigate this point, the following experiments were made : — A sample of lactic acid w^as taken, which had been sold as chemically pure ; this was tested for acetic and butyric acids, but gave no indication whatever of a trace of them being present. This was diluted with pure distilled w^ater, free from carbon dioxide, and abso- lutely neutral to phenolphthalein, until of a strength equivalent to'y^o of that of centinormal acid. In a distilling apparatus, consisting of a Wurtz flask and glass (Liebig’s) condenser, 110 c.c. of this dilute acid w^as sub- jected to distillation until 100 c.c. had come over : the distillate on titra- tion possessed an acidity equal to 2*1 c.c. of centinormal acid. The residuum in the flask when titrated was found to require 63*3 c.c. of centinormal soda. In another experiment the original acidity was equivalent to 45 C.C., that of the 100 c.c. of distillate to 3*7, and that of the residual 10 c.c. to 35*1 c.c. of centinormal acid. In the one case about a thirty-seventh, and in the other a tw'elfth, of the total lactic acid had come over with the distil- late. It may be taken as a general result that, working with very dilute acids, the quantity of lactic acid found in the distillate is not very large, but it is to be feared that it is liable to obscure conclusions based on Du- claux’s system of fractionation. It Avill be noticed that in these experi- ments there is a considerable loss of acid, as the sum of the acidity of the distillate and the residuum does not agree with that of the quantity of acid originally taken. In order to determine whether there was any loss by a portion of the acid escaping condensation, the apparatus was fitted with nitrogen bulbs containing centinormal soda, as shown in Fig. 116. In a number of experiments higher and more regular results' were thus obtained, showing that some of the acid escaped as steam. This was particularly noticeable when the distillation was accompanied by “ bumping.” Still BREAD-MAKING. 439 the amount of loss thus accounted for was nothing like sufficient to cover the whole of the deficiency. A further investigation was made as to the reaction to acids of the flasks themselves, and it was found that the alkalinity of a number of flasks was more than sufficient to entirely vitiate the result of experiments made with them. Thus, for the purpose of testing, 110 c.c. of distilled water, free from carbon dioxide and neutral to phenolphthalein, were distilled in a Wurtz flask until reduced to 10 c.c. This residuum was titrated, and re- quired 13*6 c.c. of centinormal acid. Another 110 c.c. of the same water was boiled down in a platinum basin, and the remaining 10 c.c. titrated : 0*1 c.c. of N/lOO acid produced distinct acid reaction. New flasks are found to yield a much larger quantity of alkali to water than old, and no doubt the glass of some flasks is far more soluble than that of others. Thus affiew 400 c.c. Wurtz flask was washed thoroughly, rinsed in dilute sulphuric acid, then washed with distilled water, and attached to a “ return condenser (see fat determination. Fig. 113, Chapter xxvii.). In the flask were placed 250 c.c. of distilled water, 3 drops phenolphthalein, and 1 c.c. of decinormal acid. The leading tube of the flask was closed, and the water caused to boil until a pink colouration appeared. Another c.c. of decinormal acid was then added and the boiling continued, this operation being several times repeated. The following are the results : — 1st. c.c. of acid was neutralised by alkali dissolved from flask in . . . . . . . . . . 35 minutes. 2nd. c.c. of acid ,, ,, ,, 28 ,, 3rd. c.c. of acid ,, ,, ,, 37 ,, 4th. c.c. of acid ,, ,, ,, 45 ,, 5th. c.c. of acid ,, ,, ,, 40 In the next place a flask of “ Jena Utensil Glass was similarly tested. One c.c. of decinormal acid was added to water, as before, and the boiling continued for 2 J hours ; at the end of which the contents of the flask w^ere titrated, and found to possess an acidity of 0*5 c.c., showing that only 0*5 c.c. of decinormal acid had been neutralised in that time. The following experiment may now be described : — A mixture of one part “ Red Dog '' flour with four of baker's grade spring American flour was made. There were taken 3 lbs. of this mixture, | oz. distillers' yeast, J oz. salt, and very warm water. A sponge was first made, which had a temperature of 109° F., afterwards a dough which stood at 84° F. The sponge and dough stood altogether 24 hours in a warm place, and then smelt sour and incipiently putrescent. During the time of standing it was freely exposed to the air, and several times was “ handed up " so as to work the outer skin into the mass of the dough. At the end of this time a portion of the dough was reserved for direct tests, and the remainder baked slowly in a slack oven. (The object of the whole of the treatment was, of course, to get as sour a sample as was well possible.) Dough . — To determine total acidity 10 grams of the dough were taken, broken down with neutral distilled water and titrated with N/IO soda and phenolphthalein (this indicator was used throughout) : — required, 10*9 c.c. = 0*981 per cent, of total acidity, reckoned as lactic acid. For the subsequent tests 50 grams of dough were taken and made up to 400 c.c. with distilled water, 1 c.c. of chloroform having been added. This was thoroughly mixed by repeated shakings, and allowed to stand over night : of the clear supernatant liquid, 230 c.c. were pipetted off the next morning. In 10 c.c. of this the acidity was determined, being equiva- lent to 11*8 c.c. of centinormal acid. Of this liquid, 110 c.c. were taken 440 THE TECHNOLOGY OF BREAD-MAKING. and subjected to distillation by Duclaux's method in a “ Jena ” flask : the liquid frothed so that distillation could only be conducted with extreme slowness, occupying altogether about 2 hours. The following are the results : — 1st. 10 c.c. distillate, 0*35 c.c. Y/lOO acid = 3-6% of total distillate. 2ud. 045 = 4-7 5 ? 5 j 3rd. „ 0-55 = 5-7 5 J 5 5 4th. „ 0-55 = 5-7 ? ? ? ? 5 th. ,, 0*60 = 6-2 ?? ? J 6 th. „ 0-60 = 6-2 ? ? ? J 7th. . „ 1-05 = 10-9 8th. „ 1-70 = 17-7 ’ > ? ? 9th. 55 L7o ,, = 18-2 55 53 10th. 55 2 -00 =29-8 5 5 5 3 1 1th. in flask 115 4 Total acidity of 110 c.c. = 129-8 ; total acidity of distillate = 9 -6 ; acidity of residuum = 115 -4 ; loss, 129 ‘8— 125-0 = 4*8 c.c. (The same flask evolved, in the blank experiment, alkali equivalent to 5*0 c.c. of Y/lOO acid in 2J hours.) These results not only afford no evidence of the presence of butyric acid, but are even lower in the early stages than those of pure acetic acid. It seems probable that with the very slow rate of distillation absolutely neces- sary, the acid in the earlier stages recondenses in the upper parts of the flask, and so the proportion distilled over does not conform to Duclaux's table. Another 110 c.c. of the same 230 c.c. of liquid was evaporated to dryness in a platinum basin over a water bath, re-diluted with 50 c.c. of water, and again evaporated to dryness : the residual acidity was equi- valent to 113*5 Y/lOO acid. The division of acid in this liquid into fixed and volatile agrees closely in both tests. Taking that in the platinum basin as being the more correct, we have out of 129*8 of total acidity, 113*5 of fixed, and 16*3 c.c. of volatile acidity. Reckoning these as percentages on the whole dough, we have in solution 0*74 of fixed acid (lactic) and 0*07 per cent, of volatile (acetic) acid. In strictness, it must also be remembered that any carbon dioxide present in the dough is also estimated as acetic acid, making this result too high rather than too low. Bearing in mind Balland’s investigations. Chapter XXVIII., in which he shows that a con- siderable quantity of the acid of flour is retained by the solid matter, and not given up to a filtered solution, the acidity of the remaining 170 c.c. of mixed liquid and residual flour solids was also determined. This was found to contain acid equivalent to 275 c.c. Y/lOO acid. As dough contains approximately 42 to 45 per cent, of water, the 50 grams taken will contain about 50 — 22 = 28 grams of solid matter. Therefore the residual 170 c.c. will consist of about 170 — 28 =: 142 c.c. of liquid and 28 grams of sohd residue : and the total 400 C.C., of 372 c.c. of liquid and 28 grams of solid. But as the residual 170 c.c. contains 142 c.c. of liquid, the acidity of which is 1*18 per c.c. (by direct determination), then 142 X 1*18 = 167*5 c.c. acidity due to the liquid portions. Its total acidity, 275—167*5 = 107*5 acidity remaining in the solid matter. Calculating this as lactic acid, 107*5 X 0*0009 X 2 =0*193 per cent, of acid remaining in solid matter. The 372 c.c. of solution must contain, as by estimations on 110 c.c., the following quantities of fixed and volatile acid : — 1 13 5 X 0009 X 2 _ 0.^02 per cent, fixed acid reckoned as lactic. 16 3 X 372 X 0 0006 x 2 _ 0.000 00 nt. volatile acid reckoned as acetic 110 ^ BREAD-MAKING. 441 Summing up these results we have — Dissolved fixed acid (lactic) . . 0-792 ,, volatile (acetic) . . 0-066 Undissolved acid, remaining in solids . . . . 0-193 Total acidity by c irect determination . . 1-051 . . 0-981 Difference .. 0-070 Bread . — In common with the dough, the bread smelt not only sour, hut of putrefactive products. The first estimation made was of mois- ture, of which there was 40*4 per cent., leaving 59*6 per cent, of dry bread solids. The percentages of acid are given on both the moist and dry bread. The total acidity was determined on 10 grams, and amounted to 10*1 c.c. of N/IO acid = 0*912 per cent, of acid reckoned as lactic acid on the moist bread. It may be of interest here to point out that 10 grams of dough = 10*9 c.c. of N/10 acid, and that approximately 10*6 grams of dough are required to make 10 grams of bread. 10-6 grams of dough have an acidity = 11-55 c.c. N/IO acid. 10-0 ,, bread ,, = 10-10 ,, Acidity lost during baking = 1-45 ,, 1-45 X 0-006 = 0-0087 grams acetic acid. By this estimation, therefore, the bread has lost of acidity, reckoned as acetic, 0*08 per cent. As the bread still contains volatile acidity, and this amount is slightly less than the volatile acidity of the dough, the assump- tion is that a slight amount of lactic acid has been volatilised in the oven. An aqueous extract of the bread was made in precisely the same manner as with the dough, 50 grams being taken and made up to 400 c.c. with the addition of 1 c.c. of chloroform. The following data were obtained on the elear supernatant liquid, of which 220 c.c. were removed : — Total acidity of 10 c.c. = 9*3 N/lOO acid. 110 c.c. were subjected to distillation by Duclaux’s method, and boiled regularly and speedily. The following are the results : — 1st. 10 c.c. distillate, 0-80 c.c. N/lOO acid 6-5% of total distillate. 2ad. 0-85 = 6-9 5 > 5 > 3rd. 0-85 ? ? = 6-9 5 5 4th. 0-95 ?? = 7-7 5 5 5 5 5th. ,, 1-10 ?? = 9-0 5 5 55 ' 6th. ,, 1-10 ?? = 9-0 5 5 55 7th. 1-25 5 ) = 10-2 5 5 5 5 8th. 1-45 ?? = 11-7 5 5 5 5 9 th. 1-65 ? ? = 13-5 5 5 5 5 10th. 2-20 ?? = 17-2 5 5 5 5 11th. in flask Total acidity of 90-7 110 c.c. = 102*3 ; total acidity of distillate = 12*2 ; acidity of residuum = 90*7 ; gain, 102-9 — 102*3 = 0*6 c.c. of N/lOO acid. These results are not very far apart from acetic acid, but are slightly on the formic rather than the butyric acid side. 100 c.c. were evaporated in a platinum basin, and gave 79*0 c.c. A'/lOO acidity, equal to 86*9 on 110 c.c. 102*3 — 86*9 = 15*4 c.c. of volatile acid. Working these out as percentages of lactic and acetic acids, we have 0*626 of lactic and 0*075 of acetic acid on the whole bread. 442 THE TECHNOLOGY OF BREAD-MAKING. The residual liquid together with bread solids was next examined : the total volume was 400 — 220 = 180 c.c. As 50 grams of bread were taken, the bread solids were 30 grams. Therefore the residual 180 c.c. consisted of 180 — 30 = 150 c.c. of liquid and 30 grams of solids, and the total 400' consisted of 370 c.c. of liquid and 30 grams of solid. The total acidity of the residual liquid and solids together is 306-0 c.c. Y/lOO acid. But as this contained 150 c.c. of liquid, the acidity of which is 0*93 per c.c., then 150 X 0-93 = 139-5 c.c. acidity due to the liquid portion. The total acidity, 306-0 — 139-5 = 166-5 acidity remaining in the solid matter. Calculating this as lactic acid, 166-5 X 0-0009 X 2 = 0-299 per cent, of acid remaining in solid matter. The 370 c.c. of solution must contain, as by estimation on 110 c.c., the following quantities of fixed and volatile acid : — 86-9 X 370 X 0-0009 x 2 no r~ 15-4 X 370 X 0-0006 x 2 no — 0-526 per cent, fixed acid reckoned as lactic. = 0-062 per cent, volatile acid reckoned as acetic. Summing up these results, we have — Dissolved fixed acid (lactic) . . . . . . 0-526 per cent. ,, volatile acid (acetic) . . . . . . 0-062 ,, Undissolved acid remaining in solids . . . . 0-299 ,, 0-887 Total acidity by direct determination . . .. 0-912 Difference . . . . . . . . . . 0-025 Distillation in Vacuo . — In the next place, 500 grams of the bread were taken and distilled in vacuo by the method described in Chapter XXVIII. ; the bread being raised to a temperature of 120-125° C. The amount of distillate was 220 c.c., of which 10 c.c. were taken for determination of total acidity, and were found to possess acidity equal to 11*4 c.c. Y/lOO acid. Ten grams of the residual dry bread had an acidity equal to 16-0 Y/IO acid. Calculated as percentages on the whole bread, these are equivalent to 0-30 per cent, of volatile (acetic) acid, and 0*864 per cent, of fixed (lactic) acid. Of the distillate, 100 c.c. were evaporated to dryness in a platinum basin and taken up with distilled water ; the addition of one drop of Y/lOO soda gave an alkaline reaction with phenolphthalein, showing that the distillate was to this extent free from fixed acid. The remaining 110 c.c. were distilled by Duclaux’s method in a “ Jena flask, with the following results : — 1st. 10 c.c distillate . . X/lOO acid = 5-80 c.c. A. Per cent, of = total distillate. 6-4 B. Per cent, total acid in 1 4*6 2nd. ? 5 6-60 „ 7-3 5-3 3rd. ? 9 7-70 „ 8-5 6-2 4th. 99 8-30 „ 9-2 6-6 5 th. 9 9 8-40 „ 9-3 6-7 6 th. 8-80 „ 9-8 7-1 7th. 9 9 9-65 „ 10-7 7-7 8th. 9 9 9-80 „ 10-9 7-9 9th. 9 9 11-35 „ 12-6 9-1 10th. 9 9 13-50 „ 15-0 11-0 11th. in flask 34-35 „ — 27-9 BREAD-MAKING. 443 Total acidity of 110 c.c. = 125*4; total acidity of distillate = 89*9; acidity of residual 10 c.c. = 34*35 ; loss, 125*4 — 124*25 = 1*15 c.c. of iV/lOO acid. On referring to the table of distillation of mixtures of acetic and butyric acids, Chapter XXVIII., and comparing column A with that for a mixture of 20 parts acetic to 1 part of but 5 rric acid, the figures closely agree, being distinctly on the butyric acid side of pure acetic acid. It may be con- sidered proved that a trace of butyric acid is present, equal to approximately of the amount of acetic acid.i Calculating into percentages, we have of the total acidity, 125-4 x20 = 119-4 c.c A/lOO acid due to acetic acid ; 6-0 c.c. ,, butyric acid. 21 125-4 Then as 110 c.c. of distillate were obtained from 250 grams of bread, 119-4 X 0-0006 X 2 a aoo 4 . f ^ 1 • 1 , 11 , i — = 0-028 per cent, of butjrric acid m whole bread, 5 and ^ ^ ^ 0-00 08 8 x 2 ^ 0-002 per cent, of butyric acid in whole bread. 5 Summing up, we have the following as the general results of the different analyses, expressed in percentages, those on bread being calculated on both the whole bread and dry residue : — Bread. Dough. Whole. Dried. Total acidity by direct determination 0-981 0-912 1-521 Dissolved fixed acid (lactic) 0-792 0-526 0-876 ,, volatile acid (acetic) 0-066 0 -C 68 0-103 Undissolved acid, remaining in solids. . Distillation in Vacuo — 0-193 0-299 0-498 Fixed acid (lactic) . . 0-864 1-440 Volatile acid (acetic) Fractional Redistillation of Vacuum Distillate , — 0-030 0-050 Acetic acid . . 0-028 0-047 Butyric acid 0-002 0-003 Comparing the results of the two different methods of analysis employed, we find that with aqueous distillation about yh of the total acid in both dough and bread was found to be volatile. Employing the dry distillation method on bread, yy of the total acid was volatile at 120° C. in vacuo. As to the relative accuracy of the two processes, the former presents the initial difficulty that the whole of the acid is not obtained in the aqueous extract ; and, further, that a portion at least of the lactic acid distils over with the steam. It may, on the other hand, be objected that the whole of the acetic acid is not volatilised by the treatment in vacuo. Weigert, however, has shown that by distilling wines in a vacuum, the whole of the acetic 'acid can be obtained {Zeitsch, filr Analyt. Chemie., 1879, 207). A number of other comparative determinations were made, but in all cases the aqueous extract method gave considerably higher volatile acids than distillation in vacuo. ^ Duclaux points out that with the use of a larger distilling flask a higher proportion of acid remains in the residual 10 c.c., that is, that with a greater proportion of return condensation, more acid escapes distillation. As slow distillation also means more return condensation, the same result follows. The use of charged trap-bulbs, E, F, Fig. 116, with the distilling apparatus, necessitated slow working ; hence the general error of experiment is in the direction of lessening the apparent quantity of butyric acid. 444 THE TECHNOLOGY OF BREAD-MAKING. The following experiments were conducted with the view of studying the progress of sourness with the prolongation of fermentation : — A. Series . — Quantities taken — 15 lbs. spring American 1st patent flour, 9 lbs. water at 40° C. (104° F.), 4 oz. compressed distillers’ yeast, and 2 oz. salt. A ferment was first set with all the water and a portion of the flour : in 40 minutes the dough was made, and had a temperature of 27° C. (80° F.). It was maintained at this temperature for 20 hours, and then allowed to stand at the temperature of the room for another 24 hours. At intervals, as given in the following table, the dough was “ knocked down,” re-kneaded, and a portion of 2 lbs. 3 oz. taken and baked into a loaf. B. Series . — Quantities taken — 12 lbs. spring American bakers’ grade and 3 lbs. low grade (red dog) flour, other ingredients as in A. Treatment precisely as in A. The following are the times at which loaves from both series were baked : — No. 1. Put in oven 3J hours after setting ferment. „ 2. „ 6 „ 3. „ 9 „ 4. „ 12 ,, 5. „ 15 ,, 6. ,, 20 „ 7. „ 44 _ The following were the- characteristics of the respective loaves : — A. Series. No. 1. Sweet in smell and taste. ,, 2. If anything, slightly darker in colour ; slightly maAvkish smell and taste, not sour or yeasty, crust paler. ,, 3. Colour darker, mawkish flavour disappeared, incipient sour smell, but no sour taste. ,, 4. Colour darker, loaf heavy and close, somewhat yeasty smell, but no decided sour flavour. ,, 5. Small and close, colour about same as 4, sour smell ; taste, acid and disagreeable. ” I Sour and putrescent. B. Series. No. 1. Characteristic odour of bread from low grade flours, but perfectly sweet in taste and smell . ,, 2. Colour very dark, sour smell, taste slightly sour. ,, 3. Colour changed from yellowish to dark reddish brovn. Less sour smell than 2. Unpleasant taste, rather of decomposition than acidity. ,, 4. Reddish brown colour much intensified. Slightly sour smell. Taste similar to 3, but more marked. ,, 5. Colour as 4. Smell and taste intensified. ,, 6. Sour and putrescent ,, 7. Sour and putrid. None of these had the characteristic sour smell of hakers* sour bread^ The following are the results of determinations of acidity, the total being determined on the whole bread ; the volatile by distillation in vacuo ; and the fixed or non-volatile, in the dried residue from this distillation.^ 1 The whole of these distillates were subjected to fractional distillation by Duclaux’s method. Owing, however, to subsequently finding that the flasks used gave a strong alkaline reaction, the authors do not feel justified in quoting the results as trustworthy, and therefore have not inserted them. The same remark applies to a large number of other Duclaux estimations. BREAD-MAKING. 445 As the moisture in the different samples varied, the results are throughout calculated on the dry solids. These can be approximately converted into tliose on the whole bread by multiplying by 0*6. Percentages of Acidity in Sour Bread. No. A. Series. B. Series. Total. Volatile. Fixed, i Ratio of Volatile to Total. Total. Volatile. Fixed, i Ratio of Volatile to Total. 1 0-477 0-003 1 1 () O' 1-140 1-125 2 0-407 0-015 0-4C5 1 2 7 1-041 0-042 0-972 1 2 o 3 0-491 0-030 0-441 1 T(T 1-3C0 0-102 1-143 12 4 0-671 0-090 0-549 _] 1-647 0-252 1-269 1 5 1 1-108 0-123 0-720 i 2-289 0-123 1-314 1 1 7 6 1-110 0-087 0-747 i 2-6C0 0-113 1-746 1 2 3 7 1-457 0-059 0-9C0 1 2 4 2-823 0-131 1-980 I 2 1 Curiously in both series the total acidity is less in the second than in the first loaf : with this exception the total acidity steadily rises throughout the two series. The volatile acidity (reckoned as acetic) attains its maxi- mum in Series A. in 12 hours, and in series B. in 15 hours, after which it diminishes. The ratio of volatile to total acidity is in both cases highest with the No. 4 loaf. Apparently after that time the production of volatileacid does not keep pace with its evaporation from the dough. (It should also be mentioned that, as the loaves were analysed in the order made, the latter ones had become somewhat drier when subjected to analysis.) In conse- quence of the dark colour of the dried bread, the determination of fixed acid was difficult owing to uncertainty as to the exact point of neutrality as shown by the indicator. In these breads No. 2’s are worked more than the baker would work them in actual practice ; while No. 3 of each series is far sourer than even a 'baker’s very sour loaf. The others, of course, represent extreme results altogether outside those of actual practice. Note that in No. 3 A. the volatile acidity is only yV of the total, and in No. 3 B. yV of total acidity. In the next place are given the results of an experiment with a potato ferment, purposely allowed to proceed to extreme sourness. A potato fer- ment was made from 30 grams of potato, ICO grams of water in which the potato was boiled, 5 grams raw flour, and 10 gTams of yeast. This was fer- mented at 95° E., and maintained at that temperature over night in an uncovered shallow basin. The next morning the ferment was made up to 300 C.C., with water at 120° F., and sufficient flour added to make a slack sponge, which had a temperature of 95° F. The total acid reckoned as lactic was determined in 10 grams of the whole sponge, and the volatile and fixed acids in the filtered chloroformed aqueous extract in the manner previously described. The following were the results : — Total acidity as lactic acid .. .. 1*197 per cent. Dissolved fixed acid (lactic) . . . . 0*248 ,, ,, volatile acid (acetic) . . . . 0*053 ,, Ratio of volatile to total acid . . . . The sponge was allowed to work for 6 hours and then doughed up with more flour, allowed to work I J hours and baked. The following are 446 THE TECHNOLOGY OF BREAD-MAKING. the results of determinations on the bread. The total acidity was deter- mined on the whole bread, and volatile and fixed acids by distillation in vacuo. Total acidity as lactic acid Whole Bread. 1-158 Dried. 1-935 Fixed acid by distillation in vacuo (lactic) 1-015 1-692 Volatile ,, ,, (acetic) 0-038 0-064 Ratio of volatile to total acid 1 3 0 1 30 The principal feature is that again neither in sponge nor in dough is there more than a very small proportion of volatile acid. Following on these were some experiments made on bakers’ breads. One firm in the south of England, and another in Glasgow, were kind enough to reserve a loaf of one batch baked in the usual manner (No. 1), and also to set aside dough for two other loaves, one of which (No. 2) was baked in each case when at the utmost limit of sourness ever found in practice, and the other (No. 3) several hours after. The following are the results of analysis made as before by vacuum distillations, and in filtered, chloro- formed, acqueous extract : — English. Scotch. Whole Bread. Dried. Whole Bread. Dried. No. 1. Total acidity as lactic acid 0-362 0-604 0-258 0-431 Fixed acid by distillation in vacuo (lactic) . . Volatile acid by distillation in 0-351 0-585 0-243 0-406 vacuo (acetic) 0-0006 0-001 0-005 0-008 Ratio of volatile to total acid Dissolved fixed acid (lactic) by — 1 6 04 • — ■ aqueous distillation 0-184 0-307 — ■ — Dissolved volatile acid (acetic) 0-009 0-016 — — Ratio of volatile to total acid . . 1 19 1 1 9 — — No. 2. Total acidity of lactic acid 0-535 0-891 0-342 0-570 Fixed acid by distillation in vacuo (lactic) 0-491 0-819 0-324 0-540 Volatile acid by distillation in vacuo (acetic) 0-025 0-042 0-008 0-013 Ratio of volatile to total acid . . 1 91 ' 1 2 \ 1 4 4 1 44 No. 3. Total acidity as lactic acid 0-759 1-265 0-342 0-570 Fixed acid by distillation in vacuo (lactic) Volatile acid by distillation in 0-696 1-161 0-318 0-531 vacuo (acetic) 0-036 0-060 0-017 0-028 Ratio of volatile to total acid 1 2 1 1 2 0 1 2 0 Throughout this series also the proportion of volatile acid is very low. Excluding those examples in which acidity was pushed far beyond any instance ever occurring in practice, the volatile acids found by distilla- tion amounted to from to jjV the total acid of the dough. In the instance quoted of a loaf in the last stage of sourness, an amount of butyric acid was found approximately equal to about vV the total volatile acid. The acidity of bread may be divided among the following acids in approximately the following proportions : — Lactic acid . . . . . . . . about 95 per cent. Acetie ,, . . . . . . . . ,, 5 ,, Butyric ,, . . . . from 0*0 to about 0*5 ,, BREAD-MAKING. 447 The question has been already raised as to how far the bakers* sourness is dependent on the chemists* acidity of bread : this problem merits further examination. The particulars of the progressive series of tests given on page 444 should be studied in this connection. Taking first the A. series on patent flour, No. 4 loaf had no decided sour flavour, while No. 5 tasted acid. No. 4 had a total acidity of 0*671, while that of No. 5 was 1*108 per cent., so that a marked increase flad occurred. Comparing the B. series, No. 2 was slightly sour with an acidity of 1 *041, although No. 1 with a slightly higher acidity was sweet to the taste. It must be remembered that in the B. series the naturally strong coarse flavour of the flour used made it difficult to detect shades of acidity with the palate. Dealing with the smell. No. 3 A. Avas found to have incipient sour smell, with volatile acidity of 0*030 : turn- ing to the B. series. No. 2 has a sour smell with a volatile acidity of 0*042. On studying the higher number of each series there is a steady increase of total acid, but in both A. and B. the volatile acid is lower in these higher numbers. So that 7 A., with an exceedingly sour smell, has less volatile acid than No. 4, which it far transcends in odour. The same applies to the B. series where No. 6 contains practically the same amount of volatile acid as does No. 3, although No. 3 smells less sour than 2, while No. 6 smelt sour and putrescent. Speaking in a general way, sourness and acidity go together, and bread with a total acidity of about 0*5 per cent, and a volatile acidity of about 0*025 begins, especially in the highest class breads, to both taste and smell sour. But lower grade breads can carry a much higher propor- tion of total acidity, and have its taste masked with the natural strong flavour of the flour. But although sourness and acidity are closely associated, yet the bakers’ sourness comprehends more than is expressed by acidity, as is shown by the increasing “ sourness ” to the nose of Nos. 5, 6, and 7 of both series, and the simultaneously decreasing volatile acidity. As indi- eated in the description of the various breads, bakers’ sourness also includes and takes cognisance of incipient putrefactive changes. If this be the case, sourness ” should be accompanied by evidence of other chemical changes : as proteins break down in putrefaction into compound and simple ammonias, the following determinations were made on bread. Five grams of the bread were taken, broken down in water, and large excess of caustic soda added : the mixture was then distilled in a current of steam and the distillate col- lected in 50 c.c. of A/10 acid. Determinations were made on the three samples of English bread, particulars of which are given on page 446. The following are the percentages of ammonia (reckoned as NH3), calculated on the AAhole bread : — English Bread, No. 1 . . . . . . . . 0*39 per cent. „ „ No. 2 0*40 „ „ No. 3 0*42 The amount of increase is not very great, but as a similar increase of ammonia has been noted in other breads tested, evidence is afforded that bakers’ sourness is accompanied by other changes in the constituents of the bread in addition to the development of acidity. This question of sourness is of vast importance to the baker, and is also the baking problem on which chemistry has the most direct bearing ; it therefore merits most careful attention in all its details. Among Briant’s observations is that lactic and acetic ferments flourish best at a high tem- perature, and therefore that “ high temperatures for panary fermentation are in all cases undesirable.” The assumption that high temperatures are more usually accompanied by the production of sour bread than lower ones is so directly the opposite of many bakers’ practical experience that it requires most careful examination. Among breads which are normally 448 THE TECHNOLOGY OF BREAD-MAKING. worked at a high temperature, the following are well-kno^vn examples : — Nevilhs bread, made in London from straight grades of comparatively weak flour ; and Hovis bread, made from a meal containing 25 per cent, of germ. The temperature of the dough for the latter is about 90°-95° F., and yet these two varieties of bread are remarkably free from sourness. In preced- ing paragraphs a summary of the course of fermentation has been given, while high temperatures have been mentioned as accelerating the whole of that course ; consequently, at a high temperature, everything else being equal, the sour stage is reached in less time from the commencement of setting a ferment, sponge, or dough, than if a lower temperature be adopted. But if fermentation be arrested at the same stage of its progress, there is no more danger of bread worked warm becoming sour than that which is worked cold. The crucial point as to temperature is whether, for the same amount of carbon dioxide gas evolved during alcoholic fermentation, more acid is produced at a high temperature than a low one. In order to eluci- date this point the following experiments were made : — Mixtures were pre- pared of 50 grams flour, 200 c.c. water, and 2*5 grams distillers’ yeast, and 10 grams brewers’ yeast respectively. These were placed in the yeast- testing apparatus. Fig. 21, and fermented at the respective temperatures of 75° and 95° F., which m each case were maintained constant until 350 c.c. of gas had been evolved. The original acidity of the mixtures was deter- mined in duplicates made up for the purpose. As soon as the 350 c.c. of gas had been obtained, 2 c.c. of chloroform were added to the contents of the bottle, which was shaken up and allowed to stand until all were ready for titration, when the acidity was once more determined. Two complete series of estimations were made on successive days. In another similar experiment with distillers’ yeast the fermenting mixture was first main- tained at 95° F. until 175 c.c. of gas had been evolved : it was then cooled to 75° F., and kept at that temperature until 90 c.c. more had come over. The temperature was then again raised, and maintained at 95° until the vhole 350 c.c. of gas had been evolved. The following table gives the time required for the evolution of 350 c.c. of gas, the original acidity, the final acidity, and the amount produced during fermentation, reckoned in each case as lactic acid Time taken. Hours. Original Acidity. Final Acidity. Produced during Fermentation. Distillers’ yeast at 75° F 104 0175 0-394 0-219 95° F 31 0175 0-290 0.115 Brewers’ ,, 75° F 11 0-228 0-424 0-196 ? ? ? 5 95° F 6 0-228 0-442 0-214 Repeats — Distillers’ yeast at 75° F lU 0-315 0-540 0-225 95° F 4i 0-315 0-495 0-180 Brewers’ ,, 75° F 11 0-157 0-679 0-522 5 5* 95 95° F 5i 0-157 0-670 0-513 Distillers’ veast, partly at 75° F. and partly at 95° F. 7i 0-315 0-495 0-180 With the distillers’ yeast, in both instances there is for the same amount of alcoholic fermentation a greater development of acidity at the lower temperature ; while with the brewers’ yeast there is in the one case slightly more acid at 75° F., and in the other a slightly greater quantity at the higher temperature. In passing, attention is directed to the much higher acid- producing power of the brewers’ yeast on the second day (with a different sample) than the first. Both the practical experience of the bakery and tliese tests go to show that for the same amount of alcoholic fermentation a BREAD-MAKING. 449 comparatively high temperature is at least not more productive of acidity than a much lower one. Further confirmation of this is afforded by the advent of short systems of fermentation in which the dough is worked at high tem- peratures, and with great freedom from sourness. The last experiment was made with the object of determining whether a sudden lowering of temperature during fermentation had a tendency to increase acidity. The results show that no such increase was caused in this instance. Slackness of dough is only a cause of acidity in the same sense as high temperature, in that it accelerates the whole course of fermentation. Among breads made from very slack doughs are Manchester tin bread and Vienna bread, but neither of these are specially liable to sourness. Holding the view that much of the acidity of bread is due to acetic acid, and that the production of this acid is stimulated by the presence of oxygen, Briant advises that “ therefore fermenting dough should be kept as much out of contact with air as is possible.’" If the quantity of acetic acid present in doughs which are most intensely sour in character is but trifling, then this reason for exclusion of air no longer exists. To refer again to Vienna bread, the ferments and dough for this are beaten and exposed to air almost as much as an egg in the act of whisking, and these are rarely, if ever, sour. If a baker finds a sponge working too rapidly, and in such a condition as his experience tells him means that fermentation is likely to have overshot the mark by the time he wishes to take it, then, in order to lessen risk of sourness, he very commonly throws off the trough lid and freely exposes it to air. He finds practically that this treatment, instead of causing sourness by oxidation of alcohol, obviates it by lowering the temperature, and so retard- ing the whole course of fermentation. The following may be taken as a summary of the authors’ viev s on sour bread. (It will be noticed that it endorses several of Bri ant’s conclusions) : — 1. “ Sour bread,” as understood by the baker, is the result of a combination of bacterial fermentations. Principal among these is that producing lactic acid, which constitutes about 95 per cent, of the total acidity. The remainder is due to acetic acid, with, in very bad cases, traces of butyric acid. In addition to the development of acidity, sour, as distinct from acid bread, shows signs of putrefactive decomposition. 2. The acid and putrefactive fermentations are produced by bacteria to be found in the dough. 3. These bacteria may be introduced by the yeast, by the use of dirty vessels, and by the flour ; but their presence in the flour is the most general cause of “ sourness,” and the lower the grade of the flour, the greater is the risk of sour bread. 4. The activity of these bacteria is dependent on that of the yeast : while the latter is active, the bacteria are comparatively quiescent. With the exhaustion of the yeast, or cessation of active fermentation through the assimilation of all ferment- able material, a stage is attained in bread fermentation when bacteria are excessively active, and sourness rapidly develops. 5. Temperature and slackness of dough have but little effect on sourness, except in that indirectly they affect the speed of the whole course of fermentation, and so hasten or retard the arrival of the bacterial fermentation stage. This stage being reached, the production of sourness is accelerated both by high temperature and slackness of dough. 6. Exposure to air has no appreciable effect on sourness, and may even through its cooling action be beneflcial. 7. The two principal causes of sourness are — Allowing , the fermentation to proceed beyond the normal into the souring stage ; and the use of materials or vessels containing abnornially high proportions of bacteria, especially when employed with weak and inactive yeasts. i ... - 585. Effect of Baking on Bacterial Life. — Differences of opinion exist G G 450 THE TECHNOLOGY OF BREAD-MAKING. as to whether the act of baking destroys the life of all organisms that may be present in the dough. Unless the baking is most inefficiently conducted the temperature within the loaf should be sufficiently high to kill the yeast. The doubt is whether or not the germs or spores of other organisms are also destroyed — thus, the spores of some of the bacilli can withstand a quarter of an hour’s boiling, while a sensible proportion outlive an hour’s subjection to a boiling heat. These experiments afford grounds for supposing that such germs might continue to exist even during an hour’s baking. The observed facts of the souring of bread also point in the same direction. Two loaves may be taken, each of which is sweet when removed from the oven, and kept under precisely the same conditions ; the one after a few hours becomes sour, the other retains its sweetness. Here there is a difference in behaviour which is not due to external conditions, but to some inherent quality of the two loaves. The undestroyed germs of acid fermentation have, in the bread in which they are present, induced sourness. The only other explanation of souring is that the germs of the specific bacilli have found their way from the atmosphere into the baked loaf. Walsh and Waldo subjected this matter to exhaustive investigation. Using the accustomed precautions in bacteriological work, they procured a number of loaves of bread, and sowed portions of the interior crumb in sterilised gelatin and glucose mixture, and made plate cultivations. A few of the loaves were found to be practically sterile, while others contained a large number of organisms, including bacillus subtilis and other bacilli, also sarciua and micrococcus. Many of these organisms were unidentified by Walsh and Waldo, but it may fairly be assumed that, with lactic and butyric ferments present in the dough, they may be among those organisms which have lived through the baking. Hence they may set up their char- acteristic fermentations in the baked bread. It should be mentioned in passing that Walsh and Waldo base a very powerful argument for sanitation in bakehouses on this fact, that baking does not necessarily sterilise bread. Their view is that if non-pathogenic organisms may thus survive, so may also the pathogenic forms ; and so bread, if contaminated during manufacture, may afterwards become a source of infection. Goodfellow finds that, provided the bread be allowed to stand for three hours in a germ-free atmosphere after being baked, the loaf is absolutely sterile. That is, the act of baking, coupled with the continua- ance of the baking heat on the loaf, for the period of time mentioned, is sufficient to destroy the life of all micro-organisms. If Goodfellow’s view be correct, then the position assumed by Walsh and Waldo is no longer tenable. The conditions of keeping make a considerable difference in the after- sweetness of baked bread. Where bread is kept in a close, warm, moist atmosphere, from the time of baking or when new, it is far more likely to develop sourness and mould than if stored where it may rapidly cool and lose an}'- excess of moisture. 586. Remedies for Sour Bread. — These are to a large extent indicated in the preceding paragraphs, but as one possible cause of sour bread is a want of absolute cleanliness, it should be seen that all the precautions to insure the same are rigidly adopted. Supposing, as is sometimes the case, that batch after batch of bread is sour, or rapidly becomes so ; then see that the flour is sound and discard any very low grades ; next examine the yeast ; see more especially whether disease ferments are plentiful, and whether the yeast-cells themselves look healthy and vigorous. The baker who is not able to do this for himself should place himself in the hands of an analyst to do it for him. If any suspicion whatever attaches to the BREAD-MAKING. 451 yeast or the flour, change to some other variety which is known to be doing good work. In the next place, thoroughly clean the bakehouse from floor to ceihng. Procure some solution of bisulphite of lime, and with a brush wash floor, walls, and ceiling with it. Clean out all troughs and boards, and also wash them with the bisulphite, letting it remain in the troughs for some time. Then either scald or steam them out, and dry as rapidly as possible. These steps should succeed in freeing the bakehouse from any •disease ferments which may be present. In conducting fermentation, use a sufficient quantity of good yeast, and work at such a temperature as to get sponging and doughing over quickly. As souring is largely produced by some cause unduly accelerating fer- mentation, investigate the whole of these, and modify one or more, accord- ing to which seems faulty, so as to retard to the normal rate. Or, if deemed preferable, set later or take sooner so as to use sponges or doughs at the right stage of fermentation. Use regular brands of yeast and flour, watch- ing and adjusting these as may be necessary. Souring, if due to sudden atmospheric changes, is to a certain extent beyond control ; but it may be checked somewhat by cooling, if the too quickly working material can be caught in time. The addition of salt to a too rapidly working sponge retards the whole rate of fermentation, and particularly that of bacteria. In exceptional cases, through the presence in undue quantities of bacteria, and the use of weak yeasts, the fermentation may become abnormal, and sour fermentation accompany, or even precede, the full development of normal alcoholic fermentation. Give the bread a good baking, as bread which leaves the oven in a damp sodden condition is specially liable to become sour. When baked, cool rapidly in a pure atmosphere. Weak, unstable flours used with excess of water very frequently turn sour ; the reason is that the gluten breaks down, and much of the starchy interior of the loaf is dextrinised : the damp, clammy mass resulting constitutes a favourable nidus, or home, for after-fermentation. 587. Ropiness, Watkins. — One of the most valuable contributions to the bibliography of this subject is a paper on “ Ropiness in Flour and Bread, and its Detection and Prevention,’’ read by E. J. Watkins before the Society of Chemical Industry, on April 2, 1906, and published in the Journal of the Society for 1906, p. 350. The following is an abstract of this important paper : — Occurrence. — During hot weather bread is liable to an outbreak of the disease called “ rope.” Its first manifestations usually occur in from 12 to 48 hours after the bread leaves the oven. Nature and Symptoms . — The bread acquires a faint sickly odour, and the crumb is infected with brovmish spots, which are larger the nearer the centre of the loaf. With the progress of the disease, the spots spread and the interior of the loaf becomes moist and sticky. The infected portions may be drawn out into long threads, and hence the name of rope. With the continuation of the disease, the crumb of the bread breaks down into a molasses-like mass, and emits an exceedingly disagreeable valerian- like odour. Susceptibility. — Breads containing bran and germ, such as whole-meal, certain patent breads, and rye bread, are all particularly susceptible. Of those made from white flour, the grades composed of the heart of the endo- sperm, i.e., the best patent flours, are less likely to produce rope than the lower grade flours, which are more or less contaminated with dust and bran fragments. Origin. — All modern vTiters agree in ascribing rope to bacterial activity. 452 THE TECHNOLOGY OF BREAD-MAKING. In the case of liquids, such as beer, the condition of ropiness has been ex- haustively examined, and various organisms identified as the active agents. Morris and Moritz have traced ropiness in beer to Pediococcus Cerevisice, while Pasteur has associated it with a small globular organism 0*0012 to 0*0014 mm. in size. Ropy bread has been comprehensively investigated in Germany by Vogel, who isolated two species of bacteria which he identi- fied as belonging to the potato bacilli group, and which he named B. Panis Viscosus I. and B. Panis Viscosus II. respectively. Other workers also agree in finding potato bacilli in bread. Watkins’ Personal Researches. Cultivation of Organism. — The sticky material from the centre of a ropy brown loaf w^as removed with a sterile platinum needle and mixed with sterilised water. Nutrient gelatin, agar-agar, sterilised bread, and pep- tonised wort respectively were inoculated with this solution, and cultivated at 26° C. in the incubator. Growth occurred in all cases, and microscopic examination showed the organism to be a short motile bacillus. This was regrowTi several times in peptone wort, until a practically pure culture was obtained. Experiments on Sound Bread. — Sound loaves, two days old, were taken and cut in two with a sterilised knife. On one half .three loopsful of the wort culture of the organism were sown, and the bfead placed in a moist incubator at a temperature of 28° C. The companion was as a check placed by its side. In four such tests at various temperatures ropiness was found to have developed in the inoculated bread within 12 hours. The tempera- tures ranged from 28° to 35° C. and the growth of rope was much accelerated by the higher temperatures. In no case did the uninfected portion develop ropiness, though the test was continued until moulds had made their appear- ance. Baking Tests. — These were made with a sound patent flour, the materials being mixed in a porcelain trough, and the proportions similar to those in daily use for “ straight doughs,” viz., 280 grams of flour, 150 grams of dis- tilled water, 5 grams of yeast, 1 gram of sugar, 3*5 grams of salt, thus mak- ing a miniature sack batch with a yield of one loaf of about 400 grams. [In passing, it may be pointed out that the yeast is in higher proportion than is used in a sack batch, but no higher than is customary and advisable in making small trial loaves.] The temperature of the dough was about 31° C. ; fermentation was allowed to proceed for 2 hours ; the dough was then moulded, proved, and baked for 40 minutes at an oven temperature of 204° C. (400° F.). A series of seven such tests was made. In five tests a quantity of water, increasing from 1 to 5 c.c., was taken from the 150 c.c. of doughing water, and replaced by a corresponding quantity of the peptone wort culture of the organism. The fermentation and baking of these loaves proceeded normally, and the resultant bread was light, with a sweet normal odour, flavour and appearance on leaving the oven. The loaves were cut in two with a sterilised knife, and one half of each was placed in the incu- bator at a constant temperature and in moist air. The check halves were kept at room temperature (14°-18° C.) in a dry atmosphere for seven days, and then for another four days at the same temperature in a damp atmos- pliere. In every case where the temperature of the loaf was kept below 18° G., and whether in the presence or absence of excessive moisture, there was no development of ropiness. On the other hand, every portion to which any quantity of the culture had been added became ropy at tem- peratures between 25° and 30° C. in a moist atmosphere. The presence of the disease could be detected by the characteristic smell long before any other obvious changes in the bread had made the.’r appearance. BREAD-MAKING. 453 Further Temperature Test. — A sound^loaf was cut in two and each por- tion inoculated with 1 c.c. of a wort culture. One portion was placed in the moist chamber at 28° C. and the other in a dry cupboard at 16° C., the crumb being kept moist by the addition of sterilised water. The portion at the higher temperature became ropy in 24 hours, while that at 16° C. showed no signs of the disease at the end of 28 days though still quite moist. Conclusions. — Elevated temperature appears to be absolutely necessary to the development of ropiness in bread. Even when the bacillus is present in large numbers, moisture alone, when the temperature] is low, is incap- able of causing its appearance. Effects of Acidity. — In making wort cultures, it was found that the presence of 0*1 per cent, of acetic acid prevented the growth of the organism. Lactic acid has a similar effect. The author of the paper was therefore led to try the effect of the presence of small quantities of acid in the dough. A number of tests were made and the results recorded in which acetic acid in quantities varying from 0*3 to 1*06 lbs. to the sack were used, and large amounts of wort culture added. The general result was that acetic acid in quantities of from 0*3 to 0*7 lbs. to the sack inhibited the development of rope. The minimum quantity would appear to be 0 *3 lbs. , while any excess over 0*7 lbs. injuriously affected the gluten. The smaller quantity of acetic acid is not prejudicial to the general qualities of the bread. Lactic acid may be employed instead of acetic acid, but the action is somewhat uncertain with quantities below 0 *6 lbs. per sack. Resistance of Organism to Heat. — The bacillus of rope or its spores is exceedingly resistant to heat. Thus an active wort culture was immersed in a boiling water bath for 30 minutes on three successive days. Cultures were made from the wort after each boiling, and yielded vigorous growths. The repeatedly boiled culture was then used in the dough of a trial loaf, and baked for 40 minutes. Notwithstanding the severity of this treat- ment, the organism was still extremely active and rapidly developed ropi- ness in the bread. The author of the paper draws the conclusion that it is hopeless to recommend the baker to give bread liable to rope an extra long baking in order to prevent the appearance of the disease. Morphology and Identity of Organism. — The following are the character- istic details of this organism : A short rod with rounded ends, frequently united in pairs, seldom in chains of more than three. It readily forms ovoid spores which almost entirely fill the cell. In length, it is from 1-1 *25 P ; in breadth, 0*75 y. When cultivated in hanging drop, the organism is sluggishly motile, and is surrounded by a translucent capsule. It stains well by Gram, fuchsin and methylene blue. Spore staining very difficult, usually only successful by Muller’s method. The growth is best at temperatures between 25-40° C., stagnates at 15° C. On agar-agar, smeary white growth, brownish on looking through the medium, edges of growth irregular. On gelatin, shining, barely visible, filmy growth, very slowly liquefying the medium. On wort gelatin, white crinkled growth, slowly liquefying medium. On peptonised wort, rapid growth, rendering liquid turbid, and forming a slimy gelatinous film on the sides of flask and surface of liquid. The wort acquires a faintly urinous odour. On sterilised bread the bread becomes brownish as if saturated with syrup, and is gradually converted into a moist viscous mass, emitting a strong valerian-like odour. In milk, causes coagulation, and subsequent partial re-solution of clot. On potato, rapid white crinkling growth ensues, which turns brown with age. A peculiar burnt musty odour is observed. 454 THE TECHNOLOGY OF BREAD-MAKING. The foregoing characteristics point to the organism as being identical’ with Bacillus mesentericus fuscus (Fliigge, Lehmann and Neumann^ Atlas of Bacteriology, p. 326, Plate 43). Habitat. — The bacillus is a frequent inhabitant of soils, vegetables, including potato, and doubtless also the cereals. Infection of Doughs. — The most important question to the practical baker is how his doughs become infected. Methods generally advocated for prevention and cure of rope hold bakers almost entirely to blame for its appearance in the bakery. For example, it has been ascribed to damp- ness, accumulation of dirt in false bottoms and crevices of troughs, etc. The suggested remedies have consisted of directions for purification and sterilisa- tion of the bakehouse and all its appliances. These have frequently proved totally inadequate. Flour. — A complete change of fiour has in more than one case resulted in the complete disappearance of the disease. The experience was cited of one large firm of bakers who found that this discarding of their old flours and their replacement by flours from another source resulted in an imme- diate disappearance of the trouble. Baking tests were then made on each brand of flour in the old stock, taken separately, and all but one were found to be perfectly sound. Every blend used into which this flour had entered was found to yield ropy bread. The evidence was conclusive that this flour had been the means of introducing rope into the bakery. The author of the paper made a series of bacteriological tests with this flour. One gram of the flour was mixed with 100 c.c. of sterile distilled water, and 1 loopful of the mixture added to various culture media. The growths obtained were identical with those previously isolated from ropy bread. Sterilised bread was successfully inoculated by the addition of 1 loopful of the flour mixture, blank check tests remaining unchanged. Repeat cultures of the organism were made in peptone wort, and these in turn, when added to the dough, induced rope in loaves made from sound flour. On making loaves from the suspected flour alone, portions maintained at 26°-30° C. in a moist atmosphere developed rope, while the check portions, preserved at a temperature of 14°-16° C. remained sound for as long as 14 days. These tests show that the bacillus was undoubtedly present in this sample of flour. Effect of Yeast. — In order to determine whether the yeast played any active part in the development of rope, some loaves were made with this flour and a commercial baking powder. On being tested, rope developed in the same way and at the same rate as in the yeast-made bread, showing that ropiness is independent of the presence of yeast. Modern Practice. — In modern practice, the author of the paper regards the flour as the only material responsible for the appearance of this disease. Occasionally in the past, the bacillus may have been introduced by the use of potato ferments ; but the employment of potatoes is now almost obsolete, and the fact that the rope bacillus is known to commonly exist in potatoes should furnish a strong additional reason for their abandonment in bread- making. Practical Test for Rope in Flour. — The following test is intended for the use of practical bakers and millers. It is so delicate that a positive result is obtained from 0*02 gram of a ropy flour, while there is no fear that a genu- inely sound flour will be condemned by its employment. Ten test tubes (6 in. by I in.) are washed, thoroughly boiled in water for I hour, rinsed* and drained. When drained, they are baked at 232° C. (450° F.) for 3 liours in order to completely sterilise them. [A baker’s oven at full bread- making heat sufficiently answers the purpose.] When cool, place in each tube a finger of bread 3 inches by \ inch by J inch, cut from the centre of the BREAD-MAKING. 455 same 2-day old loaf. (The average weight of each piece is 5 grams.) Moisten each piece with 5 c.c. of recently boiled distilled water, then plug all tubes ^vith cotton-wool [previously sterihsed by baking to a very light brown tint]. Sterilise the tubes and their contents by immersion in boihng water for 1 hour on three successive days. These tubes are conveniently pre- pared in batches a few days previous to being required. In order to test a flour, 2 grams are taken from the sample and well mixed with 100 c.c. of distilled water. The beaker containing the mixture is placed in a boiling water bath for 30 niinutes, in order to destroy all organ- isms except spore formers like the rope bacillus, etc. To seven of the series of ten prepared tubes add successively 1 to 7 c.c. of the boiled flour mixture, leaving the three remaining tubes to serve as checks. Immediately the tubes have been inoculated, the wool plugs are replaced and the whole ten tubes put into an incubator of 28° C. In the bakery, they may be put in a prover, or in a position near the oven where that temperature is attained and where they will be free from dust. The tubes must be examined at the end of 24 hours, both for the appearance of the bread, and for the smell of ropiness. If the rope bacillus is present, the whole of the inoculated tubes will usually show signs of it. Should only a portion of them, it is well before condemning the flour to repeat the test. In any case the check tubes must remain perfectly sound, or the experiment must be rejected. The experiment should be continued for another 24 hours, and the tubes again examined at intervals. If there is no indication of ropiness in 48 hours, the flour may be passed as sound. Beyond that time the development of moulds and other organisms interferes with the success of the test. Summary . — Ropiness in bread is produced by varieties of B. Mesen- tericus (Fliigge), introduced into the dough through the flour, in which it sometimes occurs in large numbers, possibly coming from the bran coatings. Breads containing bran and low grade white flours are most prone to develop ropiness. The bacillus is a proliflc spore former, the spores being capable of resisting high temperatures for prolonged periods. Once present in the dough, development of the bacillus, after bread has been made, depends partly upon the reaction of the bread and partly upon atmospheric conditions. Bread is only faintly acid in reaction and always insufficiently so to naturally prevent the development and spread of ropiness, but if the acidity be increased by addition of small quantities of acetic acid to the dough,, development can be prevented. Low temperature and dryness of the bread store tend to suppress develop- ment, but the maximum temperature of 18° C. (65° E.) cannot be exceeded without great risk. When a batch of bread is found to be ropy, all flour in stock should be at once tested, so as to locate the infected stock, and in the meantime fresh supplies of flour from a different source should be laid in. When the infected batch of flour has been discovered, it should be iso- lated, so that it can be worked up under those conditions which are most unfavourable to the development of the bacillus, Le., the doughs being made slightly acid and the bread being quickly cooled and kept at low temperature during storage. Such flour might advantageously be kept ’ until the colder months, when the prospects of development are at a mini- mum. During the summer months, the danger of purchasing ropy flour may be entirely obviated by the apphcation of the bread tube test before buying. (Jour. Soc. Chem. Ind., 1906, 350.) 456 THE TECHNOLOGY OF BREAD-MAKING. Watkins’ experiments would have been more complete had they included investigations as to how far the development of ropiness was affected by the comparative moisture of bread at temperatures slightly higher than the lower limit of activity of the rope bacillus. He has made it perfectly clear that with a temperature below 18° C. the presence of moisture does not cause the development of ropiness. At 20° C., there would probably be a much more rapid development in a moist loaf than in a very dry one. Some measurements of this stimulating effect of moisture would have added to the value of a very valuable paper. Previously published recommendations to the baker to give his bread an extra long baking, in case of his being troubled with rope, were not probably based on any hope thus to kill the rope organism, but rather to make the bread drier, and thus a less favour- able medium for the spread of this disease. There can be little doubt that Watkins has traced the source of many if not most of the cases of ropiness which trouble the baker. But granted that the flour is the channel of introduction ; when once the rope bacillus has permeated the troughs and other utensils, the whole of the advocated precautions for cleaning and sterilising these have all the force and neces- sity which has been attributed to them. The rope bacillus is a very ready spore-forming bacillus, and a bakery is from its nature and character a place where spores are readily liberated and disseminated through the atmosphere. There are frequently cases of rope which it is almost impossible to explain otherwise than by aerial infec- tion. Such cases are those in which a complete ehange of flour has not cured the disease, and where one miller’s flour is producing ropy bread in one bakery, while the same flour is yielding perfectly sound bread in another. The cleansing and sterilising of a whole bakery is not necessarily therefore a useless proceeding, but may be an absolute necessity, should the entire building become infected with the rope bacillus. These references are made not with the view of discounting the conclusions arrived at by Watkins, but rather with the object of indicating some possible additional sources of infection and the precautions to be in those cases taken. The reading of the paper was followed by an interesting discussion, the more important points of which are here given. The chairman, Sala- mon, drew attention to the strong smell of acetic acid exhibited by a speci- men loaf, and inquired as to what would be the effect of traces of nitrogen peroxide on this bacillus in flour, in the manner used for bleaching purposes. Jago asked whether the author had tried using the odourless mineral acids as sulphuric or phosphoric acid, and expressed a doubt as to whether the baker would regard the substitution of sourness for ropiness as an advan- tage. He pointed out that the presence of dextrinous or gummy bodies in bread, caused it to become ropy much more readily than did the drier types of bread. Hooper insisted on the necessity of flour being kept dry and not allowed to get damp, remarking that many possibly mischievous organisms were more widely spread than was commonly supposed, and were held in check by avoiding the conditions necessary for their develop- ment. Humphries found that the addition of 0*25 per cent, of lactic acid was quite sufficient absolutely to spoil bread for commercial purposes. Briant found ropiness to be generally associated with excessive moisture in bread, and also regarded the addition of acid as causing bread to become chaffy in character. Rideal recommended the use of bisulphite of soda in the place of free acids for the inhibition of ropiness. Several other speakers dealt with the question of the identity of the organism. Watkins briefly replied on the whole discussion. He did not regard bleaching as having a sterilising effect on flour, since one of the flours which yielded ropy bread had as a matter of fact been bleached. Mineral acids should not, he thought, BREAD-MAKING. 457 be used in an article of diet. Calculation showed that 0*3 lbs. of acetic acid to the sack only increased the percentage of acid by 0*0708 per cent., and that quantity did not interfere with the production of a good sweet loaf. {Jour. Soc. Chem. Ind., 1906, 350.) 588. Chalk Disease in Bread. — Lindner describes a new fermentation fungus, Endomyces fibuliger, which produces the so-called chalk disease of bread. The result of the action of this organism is to form white chalky spots on bread. It closely resembles Monilia verhialis, from which it differs however by its ability to liquefy wort gelatin. The organism ferments sucrose vigorously, and also glucose, though somewhat more slowly. The original article contains a large number of illustrations of the organism. {Z. Spiritusind, 1908, 31, 162.) Faults in Bread. 589. Holes in Bread. — Instead of the even sponginess which should characterise the crumb of good bread, one is occasionally confronted with loaves in which large holes occupy considerable spaces in the interior of the loaf. For their occurrence various explanations have been offered, many of which are ingenious, while others are impossible. An interesting object lesson in their production may be gained by taking a basin of strong solution of soap in water, and blowing into it through a glass tube. A mass of bubbles is formed on the surface of the solution, which fills the whole vessel. Let it rest, and watch the gradual disappearance of the bubbles- — careful inspection will show in the interior of the mass some of the bubble walls getting thinner and thinner, until at last they collapse, and several small bubbles coalesce to form one of large size. Practical^ the same thing occurs in dough ; if allowed to get over-proved, it will be seen, on being cut, to contain a number of large holes. Good firm moulding will remove the gas from these, and make a piece of homogeneous dough for the loaf, thus remedying one cause of holeyness ; for if a loaf containing these large holes be placed in the oven, they will expand there, and thus give still more irregular aeration. The same process of a number of small holes breaking down into one big one may occur during baking in a piece of dough, which, if cut prior to its going into the oven, would show no signs of large holes. Here the cause must be lack of tenacity in the dough which forms the hole- walls, and the cause of such holes must be found in the constituents of the dough. The elasticity of dough at this stage is principally due to the gluten present, and when fermentation has been carried sufficiently far to destroy the tenacity of the gluten, breaking down into holes is a normal result : holeyness, therefore, for this reason may be an accompaniment of over- worked dough. If a series of loaves be made as suggested in paragraph 581, it is very rarely that holes are found in the earlier and under-fermented loaves. Another cause of this irregularity is the insufficient breaking down and mixing of the sponge with the water and flour of the dough. The latter is frequently made from a comparatively soft, weak flour, and if not thor- oughly incorporated wdth the sponge, leaves portions of inferior tenacity which may readily break into holes. The production of holes by dusting flour being folded up in the interior of the loaf during moulding, and then not thoroughly worked in, thus leaving blebs, which expand into holes on baking, is so absolutely a result of carelessness as to need no further refer- ence. A curious problem about holes is the liability of cottage loaves to this fault. If some of the same dough be made into “ cakes ” or “ Coburg loaves, while the remainder is made into cottages, the latter are far more 458 THE TECHNOLOGY OF BREAD-MAKING. likely to contain holes than the former. One cause of this is possibly the inefficient “ bashing down of the tops of the cottages. A more likely reason is, however, the actual shape of the loaf itself. The top, being smaller, acquires a rigid crust before the lower part of the loaf, and therefore forms a sort of protecting cap over the centre. As expansion goes on in the interior during baking, there is a line of comparatively little resistance immediately underneath the top, and greater expansion takes place in this direction. Evidence of this is afforded by the species of risen waist one sometimes sees in a cottage loaf, consisting of what looks like a third or middle piece in the loaf. This development occurs after the rest of the loaf has set ; and, as probably the interior dough has also lost much of its elas- ticity, there is the formation of a large hole rather than even expansion. Of course the occurrence of such holes means a predisposition of the dough to breaking down into irregular aeration. The causes of holes in bread may be summed up as being — careless moulding, especially of over-proved dough ; lack of tenacity and elasticity of the dough itself, due to soft and irregular flours ; insufficient mixing of sponge and dough. Cottage loaves are prone to holes because of the physical effect of their shape on expansion during baking. 590. Protruding Crusts. — On crusty bread being packed a little too close in the oven, the loaves, on expanding, touch their neighbours, and a soft crust is formed when they are in contact. Occasionally, when the dough is weak and inclined to “ run,"" it may be observed that the loaves definitely grow toward one another, forming a distinct protuberance on the side of each, as though an endeavour was being made on the part of the loaves to effect actual contact. This apparent attraction is due to the mutual cooling effect of the loaves retarding the formation of a rigid crust on the contiguous parts : expansion continues there after the other parts of the loaves are set, and hence the “ kissing "" growth toward each other. 591. Crumbliness. — ^The crumbling away, instead of cutting cleanly, exhibited by some bread, may be due to the use of harsh, dry flours, not sufficiently fermented ; or may also be caused by over-working and proof, making the loaf bigger than the gluten of the dough, at the stage of fermen- tation when baked, is able to stand and still hold the bread well together. A deficiency of dextrin and soluble starch in the bread also contributes to crumbliness. 592. Dark Line in Cottages. — At times, on cutting a cottage loaf, a dark line is seen across the contact surface between the top and bottom of the loaf. Generally when this is the case, if the loaf has any soft crust, that too is seen to be discoloured. The bread is under these circumstances fre- quently either sour, or approaching it. The primary cause of this dark line is the darkening by oxidation of some of the constituents of the flour ; this darkening goes on more rapidly in doughs made from low grade flour or which have been over worked. Proof of this darkening of dough is afforded by pressing a piece of dough down into contact with colourless glass, and letting it stand a time. The air- exposed surface rapidly becomes the darker of the two. This darkening has been found to be the result of the action of an enzyme to which the name of oxydase has been given. In making sample loaves, especially from dark flours, a streakiness is often observed. The proportionately large external surface darkens, and each time the dough is moulded, the dark portion is worked into the interior, and hence the streaky-baked bread. In any loaf which has been allowed to stand there is more or less darkening of the exterior by oxidation — on baking, this colouration is altogether masked by the caramelisation of BREAD-MAKING. 459' the crust. But where the two exteriors have been placed together, as in the surface of contact of the two parts of a cottage, the darkening effect of oxidation is preserved, and may be noticed in the baked loaf. 593. Working with Unsound or very Low Grade Flours. — In the older literature of bread-making it is interesting to read the directions given under this head ; when, through a bad harvest, wheat has either not ripened properly, or has after the reaping been badly wetted, great care is necessary in order to make a passable loaf of bread from the flour produced. But the United Kingdom can now command the markets of the world, and without any difficulty secure sound wholesome wheats at a fair price. In the present day there is practically no excuse for a baker having a sack of unsound flour in his flour room. In composition the unsound flours have a low percentage of gluten, and that badly matured ; while the soluble proteins are high, and in a com- paratively active diastatic condition. The starch granules have their walls softened dovm and often fissured. The moisture is high, so also, owing to the degradation of starch and proteins, is the soluble extract. These flours are found on testing to be weak and unstable. So far as their treatment is concerned, that commences with the wheats rather than with the Hours. A wheat harvested damp is not necessarily unsound ; these chemical changes are to a great extent an after-consequence of the dampness. Such wheats should immediately on being harvested be kiln dried at a gentle heat of about 38° C. (100° F.), until the moisture present is reduced to 10 per cent, of the whole grain. While the flour produced from the wheat thus treated may be weak, it will be fairly stable and not unsound. The gluten will be higher, and the soluble extract and proteins comparatively low. The experiments described in paragraph 494 show that even weak, damp flours may be considerably improved by gentle kiln-drying of the flour itself. Such treatment is also by far the best that can be adopted with unsound flours ; those flours which are not amenable to it should be entirely rejected for bread-making purposes. Having by preliminary treatment made the best of an unsound flour, it should be used in the dough, which should be got into the oven as speedily as possible. Or, the whole of the flour may be worked with a straight dough on a very short system, using yeast in good quantity. A little com- pressed yeast added at the dough stage will often be found of service by hastening the fermentation. As unsound flours are particularly liable to produce sour bread, special attention should be paid to the suggestions made in paragraph 584 on Sour Bread. Further reference to unsound flours will be found in the paragraphs describing other methods of aerating bread. The low grade flours of gradual reduction processes are, if from a sound wheat, perfectly sound in themselves ; yet they require some care in mani- pulation, because they contain the active diastatic constituent of the bran, cerealin, in considerable quantity. Where these flours are employed, a sponge should be prepared from a strong flour and the low grade used in the dough, or the low grade flour worked by a short straight dough system. 594. Use of Alum, Copper Sulphate, and Lime. — ^Alum, the double sul- phate of aluminium and potassium, Al2K2(S04)424H20, was formerly largely used as an adulterant of bread. This, and the other substances mentioned, behave as retarding agents to diastasis ; with unsound flours they prevent or lessen the degradation of the gluten and starch during fermentation, and so cause a loaf made from a bad flour to be larger, less sodden, and whiter, giving it the appearance of bread made from far better flour. So far, and considered from this aspect alone, the action of alum 460 THE TECHNOLOGY OF BREAD-MAKING. is remedial ; it prevents undesirable changes occurring in the flour during fermentation. There is no doubt that by the use of alum, flour, so bad as to render bread-making in the ordinary manner impossible with it, can be converted into eatable loaves ; but if necessity arises for recourse to such flours for bread-making, other processes are now known which achieve the same object by methods that are absolutely unobjectionable. The con- tinued use of alum, even in small quantity, is, according to medical evidence, injurious to health : in particular, the alum remaining, as it does, unchanged in the bread, retards the digestive action of the secretions of the mouth and stomach. As alum is injurious, and as it is used with the object of enabling inferior flour to be substituted for that of good quality, to the prejudice of the con- sumer, it is rightly considered as an adulterant, and its use made penal. Minute quantities of copper sulphate, CuSOi, have also been employed : its action is very similar to that of alum ; but as all copper salts are very poisonous, its use is even more reprehensible than that of the former adulterant. Liebig suggested the employment of lime in solution, lime-water, CaH 202 , as a means of preventing excessive diastasis during panary fermen- tation. This substance is quite as effective as alum so far as the effect on diastasis is concerned, but unlike alum it exerts very little retardation on the alcoholic fermentation caused by the yeast. Lime is soluble in about 780 parts of cold water : its solution, or what is commonly called lime- water, may be prepared by adding about 2 ozs. of recently burned quicklime to 10 gallons of water, and stirring up. A better plan is to add the lime in considerable excess, stir thoroughly, and then allow the super- fluous lime to settle. In a few hours the upper liquid becomes clear, and may be dipped off without disturbing the sediment. Some more water may then be added and the mixture again stirred ; another quantity of lime-water is thus made. This operation may be repeated several times if sufficient lime has been taken in the first place. Any vessels containing lime-water have to be kept covered, as carbon dioxide is rapidly absorbed from the air, with the formation of calcium carbonate. Richardson states that Liebig’s directions were that the flour and lime-water should be used in the ratio of 19 of flour to 5 of lime-water, and then goes on to say that that quantity of liquid not being sufficient to convert the flour into dough, the requisite quantity of ordinary water was added. He then proceeds to quote an experiment in which 19 lbs. of flour were made into bread with ordinary water, and yielded 24 lbs. 8 oz. of bread. A like quantity of the same flour, kneaded with 5 quarts of lime-’water, produced 26 lbs. 6 oz. of bread. There is evidently a mistake here somewhere : 5 quarts of water to 19 lbs. of flour means 73 quarts of water to the sack ; this quantity, so far from not being sufficient to convert the flour into dough, is something like 10 quarts more w^ater than is ordinarily used by the London baker. As on the continent the metric system of weights and nieasures is that commonly used, Liebig’s ratio was in all probability 19 kilograms of flour to 5 litres of water, the exact equivalent of which would be 19 lbs. of flour to 5 lbs. or 2 quarts of water ; this equals 29 quarts of lime-water to the sack. The deficiency is then made up by the addition of ordinary water. The baker desiring to use lime-water may make it and employ it in the proportion just stated, or he may add not more than 1 J ounces of lime to the water per sack of flour. In this latter case he must stir the water thoroughly so as to ensure the complete solution of the lime : a milkiness throughout the whole of the water would not hurt, but any lumps must be avoided. The safest method is to prepare the lime-water as a previous operation. Lime- water is used by some of the Glasgow bakers, who advertise bread contain- ing it as a speciality. The bread made with lime-water is more spongy in texture, pleasant to taste, and quite free from sourness. In the finished BREAD-MAKING. 461 bread the lime no longer exists as free alkali, because the carbon dioxide gas generated during fermentation will have completely changed it intn calcium carbonate — CaHsO^ + COo = CaCOa -f H^O. Lime. Carbon Dioxide. Calcium Water. Carbonate. Calcium carbonate, which is identical in composition with chalk, has in small quantities no deleterious action when taken into the system, and may very possibly add to the nutritive value by remedying the natural deficiency of wheat in lime salts. See paragraphs, 648-651. So far as Richardson's quotation of experiment may be depended on, it indicates an increased yield of bread by the use of lime-water : he ascribes this increase to the loss caused by fermentation when working in the ordinary manner ; but his views on this subject have already been shown to be fal- lacious. Tlie true explanation is a very simple one : the lime-water, by preventing the degradation of the gluten and the diastasis of the starch, increases the water-retaining power of the flour, and so enables the same weight to yield a greater quantity of bread. 595. Special Methods of Bread-making. — There are certain special pro- cesses employed for bread-making which must next be described. 596. “ Vienna Bread.” — This is the name applied to rolls and other light fancy bread. Vienna bread is made with patent flour and compressed yeast. No potatoes or ferment is used. Instead of water, the bread is sometimes made with milk or a mixture of milk and water. The following recipe is quoted from The Miller : — Proportions. — 8 lbs. of flour, 3 quarts of milk and water in equal pro- portions, 3J ounces of compressed yeast, and I ounce of salt. The warm water is first mixed with the milk, so as to give a temperature of from 80 to 85° F. Sufficient flour is then added to make a weak sponge, not much thicker than a batter. The yeast is crumbled, mixed well in, and the sponge allowed to stand for about 45 minutes. The rest of the flour is next added slowly, together with the salt ; the dough is then thoroughly kneaded and set to ferment for 2 J hours. All Hungarian flour may be used through- out, or the finest English milled flour may be substituted therefor. The bread is glazed during baking by the introduction of a jet of steam into the oven. 597. Leavened Bread. — In France and other parts of the continent bread is made from leaven, which consists of a portion of dough held over from the previous baking. The following description is given on the authority of Watt's Dictionary of Chemistry. A lump of dough from the preceding batch of bread is preserved ; this weighs about 12 lbs., made up of 8 lbs. of flour to 4 lbs. of water, and is the fresh leaven {levain de chef). This fresh leaven, after remaining for about 10 hours, is kneaded in with an equal quantity of fresh flour and water, and thus produces the levain de premiere ; again, this is allowed to stand for some hours (about eight), and is kneaded in with more flour and water. After another interval of 3 hours, 100 lbs. of flour, 52 of water, and about lb. of beer yeast are added ; this produces the finished leaven {levain de tout point). The finished leaven weighs about 200 lbs., and is mixed, after standing 2 hours, with 132 lbs. of flour, 68 lbs. of water, J lb. yeast, and 2 lbs. of salt. The dough thus formed is divided into two moieties ; the one is cut into loaves, which are kept for a time at a moderate temperature (77° F. and then baked). The bread thus produced is sour in taste and dark in colour. The remain- ing half of the dough is kneaded with more flour, water, yeast, and salt 462 THE TECHNOLOGY OF BREAD-MAKING. and divided into halves ; the one quantity is made into loaves, which are •allowed to ferment and then baked ; the other is subjected again to opera- tion of mixing with more flour, etc., and working as before. The sub- division is repeated three times ; the bread improving at each stage, and the finest and whitest loaves being produced in the last batch. In the more important towns this mode of bread- making is now largely supplanted by the use of distillers’ yeast, and seems now to have largely given place to methods more nearly allied to Viennese and English processes. 598. Theory of Leaven Fermentation. — In May, 1883, Chicandard com- municated to the Academy of Sciences, Paris, a theory of panification adopted by him as the result of recent researches. He first expressly states that his conclusions do not apply to fermentation as conducted in England, but to bread made on the leaven system. English bread is excepted be- cause of its being customary to add potatoes to the ferment, the gelatinised starch of which he admits may be susceptible of alcoholic fermentation. But as many English bakers make their bread from flour, yeast, salt, and water only, any alcoholic fermentation which occurs cannot be explained by the general statement that English bakers use fruit. Briefly summing up Chicandard’s conclusions, they are — “ The fermentation of bread does not consist in the hydrolysis of starch, followed by alcoholic fermentation, and is not determined by Saccharomyces, but is a result of the solution and after peptonisation of the gluten, this effect being caused by a bacterium which develops itself normally in the dough, yeast merely accelerating such de- velopment.” In proof that the gas evolved during panification is not the result of alcoholic fermentation, Chicandard states that the presence of alcohol has never been proved : in this he is contradicted by Moussette, who detected alcohol in the gases of an oven in use in France so early as 1854, and at a time when the bread was undoubtedly being made by the leaven process. In a further communication Chicandard states that he made a dough with flour, glucose, yeast and water, testing it immediately on being made, and again after standing three and seven days respectively ; he found in each case that 10 grams of the dough contained 0 *55 grams of glucose. Girard has since pointed out in the Comptes Rendus, that he has exam- ined the gas contained in dough at various stages of preparation, and finds it to consist mainly of carbon dioxide, mixed with the air originally con- tained in the flour. In some cases part of the oxygen had been absorbed, most probably, Girard thinks, as a consequence of the secondary formation of acetic acid. [The authors’ opinion is that this absorption is due to the direct action of the yeast ; which organism, as has been already demonstrated, exhibits a remarkable avidity for oxygen.] On mixing the dough vdth water and distilling, the distillate was found to contain alcohol in quantity amounting to 3*15 c.c. or 2*5 grams per kilogram of dough. The same results were obtained whether the dough was mixed with leaven or with. yeast, thus affording additional evidence that the rising of dough is due to alcoholic fermentation Boutroux, also in Comptes Rendus (113, 203-206), states the results of investigations on this point. He states, in leavens to which no yeast had ever been added since time immemorial, that he always found yeasts, and isolated five distinct species, two of which are very active in producing alcoholic fermentation. From the flour he isolated three distinct species of bacteria : a, which secretes a diastase that dissolves cooked gluten and saccharifies stareh paste, but does not attack sugar ; 6, which produces fermentation with evolution of gas, in a mixture of flour and water sterilised by heat ; and c, obtained from the bran, which produces a fermentation, BREAD-MAKING. 463 with evolution of gas in a mixture of bran and water. Bacillus a, followed by yeast, produces alcoholic fermentation. Direct experiment showed that the yeasts active in producing alcoholic fermentation can readily be cultivated in paste, but this is not the case with yeasts little active in alco- holic fermentation, nor with the bacteria, a, b, c. The yeasts can be culti- vated in paste containing 0*3 per cent, of tartaric acid, but this quantity of acid completely prevents the rising of paste to which no leaven has been added, a result which shows that the yeast is the essential agent in bread fermentation, and if the bacteria play any useful part, it is only in the pro- duction of the sugar. Flour charged with its natural microbes, mixed with salt and water and pure yeast, and allowed to rise, contains practically the same proportions of gluten as the original flour, and hence the fermenta- tion of the gluten is not essential, but is a perturbation. Starch also is not affected to any great fextent during the process. An aqueous extract of bran, freed from bacteria, saccharifies starch paste, but not crude starch, and this is true also of the amylose secreted by the bacillus a. No other fermentable material remains but the soluble part of the flour containing the preformed sugar, dextrin, and salts. Boutroux concludes that bread fermentation consists essentially of the alcoholic fermentation of the sugar pre-existing in the flour. The yeast not only produces the gas which aerates the bread, but it also prevents the development of bacteria. The difficulty of detecting the yeast in the paste arises from the intimate manner in which it is mixed up with the dough, but the presence of the yeast cells is more readily recognised than the presence of bacteria. Laurent regarded leaven fermentation as being due to the so-called Bacillus panificans. Peters found a number of yeasts in leaven, and several species of bacteria, none however of which agreed with Laurent’s Baccilus panificans, but rather shared the properties of this so-called organism between them. Laurent most probably was dealing with an impure culti- vation. Peters found that these bacteria gave no alcoholic fermentation, and no appreciable evolution of gas in sterilised dough. 599. Alcohol in Bread, Proof of Presence of. — Pohl determined the quan- tity of alcohol in bread in the following manner : — A Papin’s digester of about 8 litres capacity was fitted to a Liebig condenser. Into this was placed a charge of 2 litres of water and 990 grams of bread cut up into small cubes. On distillation there was obtained about 500 c.c. of distillate, having a strong odour of new bread. The liquid had an acid reaction and required 1*15 c.c. of normal potassium hydroxide solution for neutralisa- tion. The united distillates from four charges of the apparatus amounted to about 2 litres, and represented 4,419 grams of bread. The distillate was saturated with sodium chloride and re-distilled in a flask fitted with a fractionating (Hempel) still-head, until half the volume had come over. The re-distillate was again saturated with sodium chloride and re-distilled until again half its volume had come over. This operation was repeated until a distillate having a volume of 120 c.c. was obtained. This was then saturated with calcium chloride and distilled until 50 c.c. had come over. The specific gravity of this final distillate was 0 *9885, and corresponded to 6*66 grams of alcohol in 100 c.c., so that 100 grams of bread contained 0 0753 gram of alcohol. (Z. angew, Chem,, 1906, 19, 668.) 600. Methods of Aerating Bread other than by Yeast. — Carbon dioxide is not only produced by alcoholic fermentation, but may also be generated within dough by purely chemical means, or may be mechanically intro- duced by first effecting its solution in water. The following description applies to aerating agents used for confectionery as well as bread-making purposes. 464 THE TECHNOLOGY OF BREAD-MAKING. 601. Aerating Agents.— These essentially con«iist of (1) substances con- taining carbon dioxide in a loosely combined condition, as in certain car- bonates, and ( 2 ) of acids or acid-containing bodies which liberate the carbon dioxide from the members of the first group. The following is a description of the more important of these bodies. Sodium bicarbonate, NaHCOa.— This body evolves carbon dioxide gas on the application of heat alone, thus : — 2NaHC03 = CO 2 + Na^COs -f- H 2 O. Sodium Bicarbonate. Carbon Dioxide. Sodium Carbonate. Water. The reaction leaves a residue of normal sodium carbonate, which has a very marked and disagreeable alkaline taste. A very slight excess causes a yellowness in fiour and an objectionable smell. These qualities are em- phasised where there are lumps of the bicarbonate not properly broken down, or when there is imperfect mixing. On treatment with acids, the bicarbonate evolves double the quantity of carbon dioxide gas : — NaHCOs + HCl = CO2 + NaCl + H2O. Sodium Hydrochloric Carbon Sodium Water. Bicarbonate. Acid. Dioxide. Chloride. With the use of hj^drochloric acid as in this case the residual body is sodium chloride or common salt. These bodies are at times used in the aeration of whole-meal bread. The salt produced takes the place in whole or in part of that always added for flavouring purposes. Ammonium carbonate (“ Volatile ”). — Under the name of “ Volatile,'’ the commercial ammonium carbonate is also sometimes used as a source of carbon dioxide gas. This body is really a mixture of ammonium carbonate and carbamate, and may be represented by the formula 2(NH4)2C03.C02, and contains in 100 parts, NH3, 28*81 ; CO2, 55*93 ; and H2O, 15 * 26 . On being dissolved in water and heated, the normal carbonate is first formed with the liberation of carbon dioxide, after which the whole of the carbonate completely volatilises, being converted into gaseous ammonia and carbon dioxide : — 2(NH4)2C03.C02 Commercial Ammonium Carbonate. 2(NH4)2C03 + COj. Xormal Ammonium. Carbon Dioxide. Carbonate. 2(NH4)2C03 = 4NH3 + 2H2O + 2CO2. Ammonium Carbonate. Ammonia. Water. Carbon Dioxide. On being heated, therefore, the whole of the carbonate is converted into gaseous products. This residue is therefore entirely gaseous, and consists of carbon dioxide and ammonia. Until the latter gas leaves the goods in which “ volatile " has been used, they have the disagreeable odour and flavour of ammonia. This substance is mostly used for aerating small porous articles which readily permit its escape. It is obviously not suited for the aeration of bread. Tartaric Acid, H2C4H4O6. — This acid, of which a description has already been given, is very soluble in water, hot or cold, and acts immediately on sodium bicarbonate in the cold, liberating carbon dioxide : — H 2 C 4 H 4 O 6 + 2NaHC03 - 2 CO 2 + Na2C4H406' + 2 H 2 O. Tartaric Sodium Carbon Sodium Water. Acid. Bicarbonate. Dioxide. Tartrate. The residual body is sodium tartrate ; it is soluble and has a bland and faintly saline taste, which is practically imperceptible in the baked goods. Commercial tartaric acid may now be obtained almost chemically pure. Cream of Tartar, KHC4H4O6. — This body, known also as hydrogen BREAD-MAKING. 465 potassium tartrate, is tartaric acid with half its acid properties neutralised by combination with potassium Consequently it has only half the strength of tartaric acid. Cream of tartar differs remarkably from tartaric acid in that it is only very slightly soluble in cold water, whereas it is readily soluble in hot water. The result of this is that when cream of tartar is used vlth sodium bicarbonate very little action goes on in the cold. But when the goods get hot in the oven a very rapid and energetic evolution of gas occurs just at the time when it is wanted. For this reason cream of tartar is an exceedingly useful bndy to the baker and confectioner. Its chemical action is shoAvn by the following equation : — KHC4H4O6 + NaHCOs = CO2 -1- KNaC4H406 + H2O. Cream of Sodium Carbon Potassium Water. Tartar. Bicarbonate. Dioxide. Sodium Tartrate. The residual body is potassium sodium tartrate, known commercially as “ Rochelle Salts,’" which like sodium tartrate is possessed of very little taste. Both sodium tartrate and Rochelle salts are aperient bodies, the latter being the active ingredient in the well-knowm Seidlitz powders. For the same amount of gas evolved, cream of tartar leaves double the resi- due in the goods that is left with tartaric acid. Commercial cream of tartar differs very much in its degree of purity. It can, however, be bought with a guarantee of containing 98 per cent, of the pure substance ; and this no doubt is the best form in which to buy the salt for aerating purposes. Acid Calcium Phosphate, CaH4(P04)2. — This salt is used to a consider- able extent for aerating purposes. It is soluble in cold water, and therefore behaves somewhat similarly to tartaric acid. In view of the fact that there is a number of possible phosphates, several reactions may occur be- tween this body and sodium bicarbonate. The following are among the most important: — CaH4(P04)2 + 2NaHC03 - 2 CO 2 + CaNa2H2(P04)2 + 2 H 2 O. Acid Calcuim Sodium Carbon Calcuim Di-sodium Water. Phosphate. Bicarbonate. Dioxide. Di-hydrogen Phosphate. CaH4(P04)2 + NaHCOs = CO2 + CaNaHsiPO.ia + HjO. Acid Calcium Sodium Carbon Calcium Sodium Water. Phosphate. Bicarbonate. Dioxide. Trihydrogen Phosphate. In the former of the above equations, one molecule of acid calcium phosphate has reacted with two molecules of bicarbonate, and has liberated two molecules of carbon dioxide. Mixed in these proportions the resultant phosphate, though still containing acid hydrogen, is neutral to litmus. Notwithstanding this, the alkali is still in excess so far as the taste is con- cerned, and if the acid salt and the bicarbonate be used in these propor- tionate quantities, the bread or other goods will have an objectionable soda taste. One molecule of the acid salt to two molecules of bicarbonate is equivalent to a proportion by weight of 13*9 parts of acid salt to 10 parts of bicarbonate. If used according to the second equation, that is, one mole- cule each of acid salt and bicarbonate, there is one molecule only of carbon- dioxide evolved, and the residual phosphate is acid both to litmus and the taste. They are then in the proportions by weight of 27 *8 parts of acid salt to 10 parts of bicarbonate, and the acid salt is in considerable excess. On making a series of tests with the acid phosphate and bicarbonate in varying proportions in bread doughs, it was found necessary to use 22*5 parts of the acid phosphate to 10 parts of the bicarbonate in order to obtain bread which was free from the objectionable taste of soda. To the 10 parts of bicarbonate, 13*9 parts of acid calcium phosphate suffice to liberate all the carbon dioxide present : it is necessary to use the excess up to about 22*5 parts in order to neutralise the soda taste. These proportions do not agree with any simple number of molecules of the two bodies. Much of H H 466 THE TECHNOLOGY OF BREAD-MAKING. the acid calcium phosphate on the market is exceedingly impure, some samples containing as much as 50 per cent, of calcium sulphate. It can, however, be bought from the best makers with a guarantee of 98 per cent, pure phosphate. Acid Potassium Phosphate, KH2PO4. — The potassium salt has been, and still is at times, employed instead of that of calcium. The reaction between it and sodium bicarbonate is as follows : — KH2PO4 + NaHCOa =- CO2 + KNaHP04 + H2O. Acid Potassium Sodium Carbon Potassium Sodium Water. Phosphate. Bicarbonate. Dioxide. Hydrogen Phosphate. The resultant potassium sodium hydrogen phosphate is neutral to lit- mus but alkaline to taste, and in practice about three molecules of acid potassium phosphate to two molecules of sodium bicarbonate are found necessary. There seems to be no advantage in having a residue of potassium phosphate rather than calcium phosphate in the goods, provided that the, calcium phosphate used is commercially pure. Acid Potassium Sulphate, KHSO4. — This salt is soluble in cold water and acts similarly to tartaric acid when used as an aerating agent. It is much the cheaper of the two and produces the following change with sodium bicarbonate : — KHSO4 + NaHCOs = CO2 + KNaS04 + H2O. , Acid Potassium Sodium Carbon Potassium Sodium Water. Sulphate. Bicarbonate. Dioxide. Sulphate. The residual potassium sodium sulphate is a comparatively tasteless body Avith aperient properties. “ Cream Substitutes.”' — These substances are lower in price than cream of tartar, and mostly consist of acid phosphates or sulphates, or mixtures of the two. The acid strength is let down to that of cream of tartar by the addition of starch, usually in the form of rice or cornflour. Strictly, these bodies are not substitutes for cream of tartar as they do not possess the same property of insolubility in cold water, and ready solubility in hot water. By careful selection and admixture, their rate of cold Avater solu- bility is considerably sloAA^ed doAvn, and AAuthin limits they can be used instead of cream of tartar. Their true analogue is not, however, cream of tartar, but rather tartaric acid. Alum, Al2K2(S04)4, 24H2O. — The alums liberate carbon dioxide from sodium bicarbonate according to the folloAA'ing equation : — AI2K2 (804)4, 24HO2 + ANaHCOa = 6 CO 2 + Al2(HO)6 + Potash Alum. Sodium Bicarbonate. Carbon Dioxide. Aluminium Hydroxide. K2SO4 + SNa^SOi + 24H2O. Potassium Sodium AA’’ater. Sulphate. Sulphate. The employment of alum in the preparation of food is regarded as an adulteration. Equivalent Weights. — The folloAving table gives the AA^eight of each sub- stance required by 10 parts by AA eight of sodium bicarbonate : — Name. Tartaric j Acid Weight. 8-93 Cream of Tartar . . . . 22-38 Acid Calcium Phosphate, about . . 22*50 Acid Potassium Sulpliate . . 16*19 Comparative Evolution of Gas. — The comparative volume of gas, mea- sured at 100° C., evolved by one part by AA^eight (1 gram) of various aerating mixtures, is given in cubic centimetres in the folio AAing table : — BREAD-MAKING. 467 NAME OF AERATING AGENT. VOLUME. Ammonium carbonate (volatile), on being heated yields — ammonia gas, 516; carbon dioxide gas, 387 .. .. .. .. .. 903 Sodium bicarbonate by action of heat alone . . . . . . . . 181 Mixture in proportion of 10 parts sodium bicarbonate to 8-93 parts tartaric acid . . . . . . . . . . . . . . . . 191 Mixture in proportion of 10 parts sodium bicarbonate to 22 *38 parts cream of tartar . . . . . . . . . . . . . . 112 Mixture in proportion of 10 parts sodium bicarbonate to 22*5 parts acid calcipm phosphate . . . . . . . . . . . . . . 112 Mixture in proportion of 10 parts sodium bicarbonate to 16*19 parts acid potassium sulphate . . . . . . . . . . . . . . 138 In summing up the general behaviour of these, and deciding as to their suitability for aerating purposes, the first consideration is whether rapidity of action is objectionable or otherwise. If the goods can be baked at once before the action of the acid and soda on each other is over, then tartaric acid and soda answer well. But it must be remembered that this action commences immediately the ingredients are wetted. On the other hand, if it be desired that no action shall occur before the goods are heated in the oven, then cream of tartar and soda are preferable, as this mixture remains quiescent until the temperature is raised. Where immediate action is no detriment, acid and soda are indicated, and this mixture possesses the advantage of leaving only about half the residue left by cream of tartar and soda. Ammonium carbonate has also a deferred action, but there is the unpleasant ammoniacal odour left in the hot baked goods. Provided this is allowed to escape, and the goods are odourless, then no residue whatever remains in them. 602. Baking Powders. — These consist of bicarbonate of soda put up with one or more of the acid bodies previously described. Baking powders are used more extensively in America than this country for bread-making^ purposes, and their composition has been made the subject of investigation by one of the State departments. They are classified according to the nature of the acid constituent they contain into three groups. Tartrate. Phosphate, and Alum powders. In the manufacture of baking powders, the acid ingredient, together with the proportionate quantity of bicarbonate of soda, is mixed with air- dried starch. This latter component increases the weight of the baking powder ; it also, owing to the hygroscopic nature of starch, helps to keep the active ingredients free from moisture. 603. Effect of Alum on Bread. — The action of alum in bread on its artificial digestion was demonstrated by a number of experiments made by Knights, and communicated to the Society of Public Analysts in 1880. Hehner has since (in November, 1892) published the results of researches on the effect on artificial digestion of alumed baking powders. The baking powMer used had the composition : — Crystallised Alum . . . . . . . . .. 45*80 Sodium Bicarbonate . . . . . . . . . . 18*71 Starch 33*40 Moisture, and not determined.. .. .. .. 2*06 100*00 Using the directions given with the wrapper, this powder, if employed for bread-making, would yield a 4-lb. loaf containing 210 grains of alum. On treating hard-boiled white of egg with pepsin solution, the addition of the 468 THE TECHNOLOGY OE BREAD-MAKING. alum baking powder, and also pure alum to the same extent as the baking powder contained, both equally retarded digestion. There were next some experiments made on flour ; and with this, while alum has a most injurious influence upon the digestion, that of alumed baking powder is but slight. With bread a series of experiments was made, in which pure bread was digested with pepsin solution and alumed baking powder and alum respectively ; with amounts of baking powder recom- mended to be taken by the manufacturer, the influence of alum and of alumed baking powder is about equal, both producing very marked retard- ing action. A physiological experiment, in which four persons took each a dose of baking powder dissolved in water and then sweetened, was made. The amount so taken was 2 grams, equal to that contained in 4 ounces of bread made according to manufacturers" directions — the resultant symp- toms were those resembling an attack of indigestion, being slight difficulty in breathing, headache, and ultimately slight diarrhoea, which symptoms lasted for several days. Subsequently to this, in 1893, a case of prosecution for the sale of alumed baking powder came before the Glamorganshire Quarter Sessions. Among other evidence given there was that of the scientific witnesses, of wLich the following is a summary : — Morgan, Public Analyst, stated that a 4-lb. loaf made according to direc- tions given would contain 360 grains of baking powMer, of which 144 grains w'ere alum. On addition of water to the baking powder a reaction occurs, in wiiich potash-alum and sodium-bicarbonate produce aluminium hydroxide sodium sulphate, potassium sulphate, carbon dioxide gas, and water. The quantity of aluminium hydroxide might be taken as one-sixth of the alum, or 24 grains to the 4-lb. loaf. On being eaten, the hydrochloric acid and pepsin of the gastric juice dissolved the aluminium hydroxide with formation of soluble aluminium chloride, which latter body was noxious to the stomach. Aluminium hydroxide was prepared from this baking powMer, mixed with w^ater, and taken with a mid-day meal. At the same meal another person drank nothing. Artificial vomiting was shortly afterwards in both cases induced, and hydroxide of alumina added to the contents of the stomach in the case of the subject wflio had drunk nothing. Both vomits w^ere then dialysed, and aluminium chloride found in each, thus showing that the hydroxide of alumina had been converted to the soluble form. Dunstan stated that aluminium hydroxide dried at 212° F. w^as soluble in the diluted gastric juice of a dog ; and, further, that such gastric juice dissolved aluminium hydroxide from bread baked with the powder. Fur- ther, aluminium hydroxide dried at 212°F. was soluble in a dilute solution of sodium carbonate of 0*3 per cent, strength, the strength of the alkali in intestinal juice. He consequently found that this alumed baking powder interfered with the digestion of starch by ptyalin, and also with peptic and pancreatic digestion. Hehner, Lauder Brunton, and others gave corrobora- tive evidence. The line of defence w^as that the preceding evidence had not shown that the baking powMer w'as injurious to health, but only that it might be. Among witnesses called for the defence was Sutton, wiio described an experiment lie had made, in which a coachman ate a pound of bread made with the- baking powder, and about two hours after had the contents of his stomach removed ; these w^ere subjected to dialysis, and found to contain no alu- minium chloride. Luff and Wynter Blyth, wiio were also present at this experiment, concurred with Sutton ; they all considered aluminium hydroxide to be insoluble under the conditions of bread digestion in the human stom- ach, and viewed Morgan"s experiments as valueless, because feebly precipita- ted aluminium hydroxide w'as much more soluble than alumin.'um hydroxide BREAD-MAKING. 469 baked in a state of actual dissemination through a loaf of bread. B, Ward Richardson followed on the same side, and was of opinion that the use of alumed baking powder was not injurious to health. Wynter Blyth con- sidered that Morgan’s aluminium hydroxide was not in the same condition as that of aluminium hydroxide baked in bread ; and, further, that alumed baking powder was not injurious to health. The decision of the Court was that the baking powder was mixed with a certain ingredient, to wit, alum, which is injurious to health, and therefore file conviction of the person selling the same was upheld. Very considerable difference of opinion was expressed during the giving of the above cited evidence as to the condition of the aluminium hydroxide and its behaviour in the stomach. Of all experiments that of Sutton was far the most conclusive, because of being made on bread manufactured with the powder. The separate addition of alum or alumed baking powder to pure bread undergoing artificial digestion, or to the contents of the stomach, involves conditions so distinct from those which hold in the actual use of alumed baking powder that comparatively little importance can be attached to the results, whatever they may be. , The obvious course would be to arti- ficially digest bread prepared from alumed baking powder against breads prepared with and without admixture of alum ; and in case of human digestion, to also experiment in the same manner as Sutton with the pre- pared bread. To throw additional light on this matter, the authors made the following series of experiments : — Three loaves of bread were prepared from, in each case 2 lbs. 3 oz. of flour, 1 lb. 8 oz. of water, 1 oz. of yeast, and | oz. of salt. At the time of mixing there was also added to No. 1, 9*35 grams of alum ; and to No. 2, 9*35 grams of alum and 4*80 grams of sodium bicarbonate ; No. 3 was left plain. The total proteins in each were determined, and a portion of the bread subjected to artificial digestion mth pepsin, the follow- ing being the method adopted : — 5 grams of the bread were taken and rubbed down in a mortar with 25 c.c. of 0*01 per cent, solution of pepsin in 0*2 per cent, hydrochloric acid, then made up to 100 c.c. with water, and digested 1 J hours at 43*5° C. The solution was filtered, and the amount of digested protein determined in the filtrate. The comparative starch digestion was estimated by rubbing do^vn 5 grams of bread in a solution of malt diastase, making up to 100 c.c., and digesting at 21° C. for one hour. Maltose was then determined in the filtrate from each. The following are the results of analysis in percentages : — 1. Alum. 2. Alum and Bicarbonate. 3. Plain. Total Proteins before digestion 8T5 7*95 8*20 Proteins digested . . Maltose found, being evidence of diges- 1*99 1*95 3*83 tion of starch . . 36*36 41*34 43*6 Other series of experiments were made, in which the same general results were obtained. The quantity of alum present, under the conditions of the experiment, retarded protein digestion to about half the rate in its absence. Practically no difference was made in this retarding action by the presence of sodium bicarbonate : in other words, the alumed baking powder was equally injurious with alum used alone. The difference in amount of starch digestion was not so marked as probably it would have been had a diastase solution of less strength been used. There is a marked difference between the alumed and the plain loaf, but in this case the retarding action of alum is largely overcome by the presence of bicarbonate in No. 2, a result, doubt- less, of the neutralising effect of the alkaline salt on the alum. 470 THE TECHNOLOGY OF BREAD-MAKING. 604. Self-Raising Flour. — The articles sold under this name consist of flour, mixed with acid tartrates or phosphates, and the bicarbonate of soda : as with baking powder, the addition of water causes the evolution of gas. Self-raising flours may be viewed as being flours sold with baking powder already mixed with them. It is claimed for the use of phosphates in this manner that it replaces these important salts which are removed from the wheat in the bran. 605. Use of Hydrochloric Acid. — In the manufacture of wholemeal bread the method is sometimes adopted of employing hydrochloric acid and so- dium carbonate in the exact proportions in which they neutralise each other : they then not only evolve carbon dioxide gas, but also yield sodium chloride, or common salt, thus ; — NaHCOa + HCl = NaCl + H 2 O + CO^. Sodium Hydrochloric Sodium Water. Carbon Bicarbonate. Acid. Chloride. Dioxide. The salt thus formed lessens the quantity which otherwise would have to be added to the bread. Great care is requisite in the proper mixing of the acid and the carbonate with the meal : it is also important that ex- actly the right proportions should be taken. A rough measurement of the strength of the acid may be made by taking a weighed quantity, say an ounce, of the bicarbonate of soda, dissolving it in boiling water in a beaker, and then adding a few drops of methyl orange solution. The hydrochloric acid should be measured, or else a quantity placed in a beaker, and weighed in it : then add the acid little by little until one drop changes the colour of the bicarbonate of soda solution from yellow to red. Then again weigh the acid containing beaker ; the loss in weight gives the quantity of the hydrochloric acid, equivalent to an ounce of the bicarbonate. Commerial hydrochloric acid is usually sold with a guaranteed density of 1*15 ; this is equivalent to about 30 per cent, of the anhydrous acid. As 84 parts of sodium bicarbonate are exactly neutralised by 36*5 of anhydrous hydro- chloric acid, and as this amount is contained in 122 parts of the commercial acid, the bicarbonate of soda and hydrochloric acid of this density should be used in the proportions of 84 of the bicarbonate to 122 of the acid, or practically in the proportions of 2 to 3 by weight. It has been recommended that 3 lbs. each of the acid and bicarbonate be used to the sack of flour : these proportions leave, however, a considerable excess of the carbonate in the bread. The great objection to the hydrochloric acid method is that the commerical acid frequently contains traces of arsenic, and thus a minute quantity finds its way into the loaf. 606. Whole-Meal Bread. — It is principally in making whole-meal bread that the hydrochloric .acid and bicarbonate method is employed. The rea- son is that, with the presence of the bran, cerealin is introduced into the dough in such quantity that, if ordinary fermentation processes be em- ployed, diastasis proceeds to a very serious extent. The excess of dextrin thus produced causes the dough to become soft and clammy, and so to offer a matrix in which sour and other unhealthy fermentations are apt to proceed rapidly. The brown colour is due to the excess of dextrinous matter contained in the bread. The rapidity of the acid treatment en- ables the bread to be got into the oven before diastatic action can have proceeded to any extent. When the fermentation method is employed for making whole-meal bread, it is customary to make a sponge with a small quantity of very strong flour, and only add the whole meal at the dough stage. How^ever made, wLole-meal bread has a great tendency to become sodden ; in order to drive off excess of moisture it has to be baked for a considerable time, consequently the loaf has often a very thick BREAD-MAKING. 471 crust, wliile the interior is still unduly moist. In summer time particularly the making of whole-meal bread is an unsatisfactory operation, as great difficulty is often experienced in producing a sound and well-risen loaf. In all the operations just described, carbon dioxide is formed in dough, and thus raises it. The chemical action which under these circumstances takes place is not, however, a complete representative of that which occurs with yeast. One of the functions of this body during the fermentation of bread is to act on the protein, and also to a certain extent on the starch ; the result of such action, when normal, is to impart to the bread a charac- teristic flavour that can be obtained by no other means at present known. 607. The Aeration Process. — One other method of aerating bread remains for consideration, and that is the system associated with the name of Dr. Dauglish. The carbon dioxide is in this method prepared apart from the bread and forced into water under pressure ; this water, which is akin to the aerated water sold as a beverage, is then used for converting the flour into dough, the whole operation of kneading being performed in a specially prepared vessel in which the pressure is maintained. The kneading being completed, the dough is allowed to emerge from the kneading vessel, and immediately rises, from the expansion within it of the dissolved carbon dioxide. Such. was the nature of the method originally employed by Daug- lish ; but now the following modification is used : — A weak wort is made by mashing malt and flour ; this is allowed to ferment until through the agency of bacteria it has become sour, in all likelihood through the presence of lactic acid. The w ater to be aerated is first mixed with a portion of this w-eak acid liquid : it is then found to absorb the carbon dioxide gas much more readily. The acid also softens the gluten. So far as the actual aeration process is concerned, this method is mechanical rather than chemical. The great objection is that those more subtle changes by which flavour is pro- duced do not occur here more than in the other purely chemical methods of bread- making before described. A common experience in eating aerated bread for some time is that it after a wliile gives the impression of rawmess. This is doubtless due to there being no such enzymic action on the proteins as results from fermentation. It is partly to meet this want that the fer- mented w ort is now added as a part of the process. On the other hand, as a compensation for this lack of flavour-producing changes, the operation* is one in which there is no danger of those injurious actions occurring of wliich much has already been said. .^Working with flours that are w^eak and damp, or even bordering on the verge of unsoundness, it is still possible to produce a loaf that should be wholesome and palatable, certainly superior to many sodden and sour loaves made from low quality flours fermented in the ordinary manner. In thus stating that it is possible to treat flours of inferior quality by this aerating method, the authors wish specially to carefully avoid giving the impression that it is the habit of those companies wliich w ork Dauglish's method to make use of only the lower qualities of flour ; they have never had any reason wliatever for supposing such to be the case. Their object in the present remarks is simply to point out the advantages possessed by this method, should circumstances unfortunately arise rendering it necessary to have recourse to inferior flours for bread- making purposes. Richardson claims for the aeration process that it is eminently suited for the manufacture of whole-meal bread. Of this there is not the slighest doubt : wffiole-meal is not w^ell fitted for fermentation methods, and the* aeration process distends the dough with gas, without the addition of any foreign substance whatever. It is also claimed for the aeration process that it enables the cerealin 472 THE TECHNOLOGY OF BREAD-MAKING. to be retained within the bread ; and that this is “ a most powerful agent in promoting the easy and healthy digestion of food.’' It is stated that this agent is retained uninjured by the aerated bread process. The author of this statement apparently overlooks the fact that diastatic action is destroyed by the subjection of proteins to a temperature approaching 212° F. However active, therefore, cerealin may be in effecting diastasis of starch during panary fermentation, its power is destroyed by efficient baking, and the bread contains no active disatatic principle. This remark applies with equal force to bread containing malt ; it is so well known that malt infusion converts starch into dextrin and maltose, that from time to time it has been introduced into bread. It must here, too, be remembered that the baking entirely destroys its diastatic action, and so causes the malt to be inert as a digestive substance. 608. Gluten Bread. — It is important that the diet of diabetic patients should contain no sugar, starch, or other compounds capable of being con- verted into sugar. For their use bread is prepared containing the gluten only of the flour. A strong flour should be selected and made into a stiff dough with water only ; this is allowed to stand for almost "an hour, and then carefully kneaded in small pieces at a time in a vessel of water ; the starch escapes and the gluten remains behind. Care is necessary in per- forming this operation, as otherwise the lump of dough does not hold to- gether. Should there be any difficulty, the dough may be enclosed in muslin prior to being kneaded. The gluten must be washed in successive waters until it no longer contains starch ; at this point the gluten ceases to render the washing water milky. When properly washed the gluten is ready for the oven, and is usually baked in small rolls or buns. As it swells enormously during baking, a very small piece is sufficient for each roll. 609. Rye Bread. — On the Continent, bread is made to a considerable extent from rye. The following are the results of analyses of samples of two such breads : — Proteins Starch, etc. Sugar Fat . . Cellulose Mineral matters Water Pumpernickel. Black Bread. 8-90 39-74 3-28 2-09 1-79 1*29 42-90 Vienna Bye Bread. 8-30 55-14 1-46 0-33 0- 97 1- 90 31-91 Pumpernickel is the well-known black bread of Northern Germany, and is regarded rather as a delicacy, being almost invariably served wdth cheese in the hotels of Berlin and other German cities. The Vienna sample is of a whiter type, containing considerably less of the bran. 610. Unsuitability of Barley Meal, etc., for Bread-making. — Questions often arise as to why barley and other cereals do not make such good bread as does wheaten flour. One reason has already been given : wffieat is dis- tinguished from the other somewhat similar food stuffs by its containing gluten ; it is the presence of this peculiar albuminous body that confers on 'wheat flour its characteristic bread-making qualities. The proteins of the other cereals, and also of peas and the other leguminous seeds, possess more active diastatic properties — consequently during fermentation they yield much dextrin, and produce dark coloured, sodden, and often sour breads. The diastase of rye is particularly active. In addition to the colour produced by diastasis, peas have naturally a dark colour of their BREAD-MAKING. 473 ■own, so that their introduction into bread would very materially affect the ■colour. In comparing barley and rye flours against that of wheat, the differences in the respective milling processes must not be ignored. The bran and germ of wheat are separated from the flour by most refined methods, while barley and rye are ground, and the meal purified, by the crudest appliances. This must of necessity make a difference in the character of the flour. 611’. Wheat and Flour Blending. — The consideration of the whole pro- blem of blending flours and wheats has been purposely postponed until this stage, in order that the reader may have before him an account of the various changes which flour undergoes during the operations of panary fermentation. These changes, in short, consist in more or less conversion of starch into dextrin and maltose, and in the gradual softening and other- wise altering the gluten of the flour. As has been previously insisted on, the gluten must have had during fermentation sufficient opportunity to hydrate and soften sufficiently ; but must not have been allowed to further change, as if so it will have lost its tenacity, and vill produce an inferior loaf. A great deal of the success of a skilled baker depends on his having acquired the experience which enables him to take his dough and place it in the oven just at this right point when fermentation has proceeded sufficiently far to get the gluten of the flour in its best possible condition. The problem is further complicated by the fact that different flours require, in order to arrive at this stage of maturity, different lengths of time in fermentation ; hence, as already explained, flours from hard wheats are commonly used in the sponge, while those from soft wheats are employed in the dough. There can be no doubt whatever that by this arrangement far better bread is produced than if the flours be used in the reverse order. It is, then, perfectly safe to state that the length of time flours require to stand in fermentation is in proportion to their hardness or stability. This being the case, the question arises as to how this end may best be secured. Probably the most keenly contested question on this whole problem of blending is whether it shall be done by the miller or the baker. Of prior importance, however, to this matter oi by whom the blending shall be per- formed is that of the baker’s actual requirements in flour. Evidently the baker who works either with a ferment and dough, or an off-ljand dough, needs but one flour for each quality of bread, and may therefore either buy a flour which suits his requirements, ready mixed by the miller, or may purchase individual flours and mix them together. With the increased adoption of straight dough systems, there is naturally a larger demand for ready blended flours. But even those who employ tliis method may often find a blend of their own more suited to their particular requirements than a single miller’s flour. On the other hand, the baker who employs the sponge and dough system yvill, in the great majority of cases, find it advan- tageous to use flours of a different class for his sponges and doughs respec- tively. As already explained, for the former he almost invariably selects a hard, strong flour, which is best made from either Spring American or the harder Russian wheats. For some methods of working, an admixture of a small proportion of softer flour is an improvement, as the proteins of the latter exercise a distinct mellowing and ripening effect on the glutens of the hard flours. For doughing purposes the wheat or flour mixture is more varied ; thus the soft, sweet, “ coloury ” flours are used at this stage ; so also is usually a certain proportion of hard flour, which, if not too much, is sufficiently softened by the diastatic action of the softer flours by which it is accompanied. 474 THE TECHNOLOGY OF BREAD-MAKING. A very interesting paper on Flour Blending was read before the Bakers’ National Association, at Belfast, by W. T. Hibbard, of Gloucester, who discussed the question of whether millers or bakers should do the blending, arguing that this should be the duty of the miller. This view was princi- pally based on the assumption that the miller’s education and training best fitted him for making accurately the necessary selections of wheat and then blending them. So long as the miller possesses this knowledge, and the baker does not, the argument is unanswerable ; but there is no real reason why the baker should not himself acquire this information and experience, and then the argument no longer applies. Dealing with the question of blending, apart from by whom performed, Mr. Hibbard’s paper contained some most useful information conveyed on somewhat the same lines as laid down in the wheat and flour dictionaries given earlier in this work. The ideal mixture recommended for'making a loaf that shall be sweet and nutty flavoured, of good size and appearance, of fine bloom, and which shall keep nice and moist for days, in fact perfection, is the follow- ing For Sponging — Per cent. High-grade Spring American Patent . . 20 High-grade firm white Dantzic . . 10 For Doughing — High-grade Cones flour . . 25 Talavera straight -grade . . 25 Fine Winter American or Polish Patent. . . . 10 Fine Hungarian . . 10 100 There is always a demand by the more advanced Bakers for flours milled from single wheats, a demand evidently based on the greater individuality which such flours naturally possess. Among these are hard Spring Ameri- cans, which can be differentiated into Manitoban wheat flours, Northern Minnesota flours, and Southern Minnesota flours, all of which have their special characteristics. Prime hard Russian wheat flours would also find a market were they obtainable. Winter American flours, both from soft wheats and also the hard Kansas wheats, may also be included in this group. So, too, may best English wheat flours, and also those from Hungarian wheats. The following are among the advantages which accrue to the baker by working on the principle of blending flours : — (1) There are frequently offering parcels of flour which possess -in a marked degree some one quality, but are deficient in others. Because they cannot well be used alone, they may be purchased at a lower figure, and the blender, by mixing, can utilise such flour to advantage. In other words, given the requisite knowledge, it is often cheaper to prepare the quality and character of flour required for use from a mixture of different qualities obtainable on the market, than to buy the actually wanted quality mixed ready for use. (2) The baker who blends flours has a greater control over the quality and character of the flour he uses in his work. Thus, he can readily either improve or diminish the value of his sponging flours by the addition of a bag or a sack of a better or worse flour : so, too, colour, flavour, and other characteristics of his flours can be readily modified at will, and much more effectively than if he simply obtains one ready-made flour from the miller. He can similarly modify a flour used for straight doughs. ' BREAD-MAKING. 475 (3) The baker can introduce each particular variety of flour at that stage of fermentation which best suits its particular characteristics. Blending affords greater chances of successful work with flour, but at the same time entails greater risks, because accurate knowledge of the pro- perties and the characters of the various flours blended is requisite, and also of their effect on each other when blended. The baker who blends should lay himself out to select flours for their predominant quality ; for example, one brand for strength, another for colour, another for flavour, and so on. By appropriate means he will judge the exact character of each of these flours in the separate state, and then can readily, with a little care, prepare whatever blends best suit his work. The modern baker will have no difflculty in finding his requirements in this direction met by the modern miller. Millers, in blending, usually first mix their wheats, and let them lie a time before sending to the rolls — if hard and soft wheats are thus blended, each exerts a favourable influence on the other in the way of rendering it more amenable to milling. Thus, a very hard wheat, and also a very soft one, are each more difficult to mill successfully than a mixture of inter- mediate character ; and consequently a miller’s argument is this — if the two flours are to be mixed after being milled, why not have the wheats first mixed, as the resultant flour is of better quality, everything else being equal, than if the two separate flours are mixed after milling ? On the other hand, certain millers have distinct and separate plants, the one for hard wheats and the other for soft, and mill and treat each separately, after- wards mixing the flours. The evidence, therefore, of even millers themselves is undecided on this point of blending before or after milling. Whether blending be done by the miller or the baker, an undoubted advantage arises from the latter having a clear idea of his exact require- ments in flour, and how they may best be met. With clear and full know- ledge on these points, whether the baker blends himself or gets that service performed for him by the miller, the result is the more economic production of a better and higher class loaf. 612. Changes in Flour resulting from -Fermentation. — A series of experi- ments has been made by the authors with the following objects : — I. Determination of the amount of gas evolved during fermentation under the described conditions. II. Investigation of the changes produced by fermentation in the com- position of the flour. III. Eflect produced by the addition of various substances to the flour on the quantity of gas evolved, and on the changes therein resulting from fermentation. Outline of Experimental Method . — In each test, 200 grams of flour were taken, and 100 grams of water at 30° C. ; these with 2 grams of salt, and 4 grams of fresh distillers’ compressed yeast formed the basis of the dough. Various additions were made as subsequently described. The doughs were carefully mixed with a spatula in a basin, and finally made by hand, but with as little handling as possible. They were then transferred to a weighed enamelled steel beaker and the weight ascertained. Waste and loss in making were thus determined. A small portion of the dough was then taken for estimation of water and solids. The remainder was carefully weighed, and the beaker, a, at once inserted in the fermenting apparatus. This consisted of a gun-metal vessel, h, Fig. 43, fitted with a glass lid, c, and an outlet tubulure, d. The vessel, h, was fixed in a water bath, e, maintained at a constant temperature by means of an automatic gas regulator, /. The tubulure, d, was connected with a gas measuring apparatus, g, similar to that 476 THE TECHNOLOGY OF BREAH-MAKING. described on page 199. The joint between h and c was made with rubber solution, and the two fastened together by means of four screw clamps, h, applied round the edges. The doughs when made had a temperature of 26° C., and the water bath was kept at that temperature throughout the whole series of experiments. The volume of gas evolved was read off at intervals, usually of one hour, and the readings continued for 6 hours, with the exception of No. IV., in which they were taken for 20 hours. The beaker of fermented dough was then removed from the apparatus and weighed. An analysis was subsequently made on the fermented dough. The following table gives the numbers of the experiments, and the sub- stances used in each. As already mentioned, the four principal ingredients were always taken in the same proportions, viz., flour, 200 grams ; water, 100 grams ; salt, 2 grams ; and yeast, 4 grams. The yeast throughout was the same brand, and that employed was selected each day from the centre of a fresh and previously unopened bag. No. I. Flour, water, salt, no yeast. ,, II. Flour, water, salt, malt flour 1 gram, no yeast. ,, III. Flour, water, salt, yeast. ,, IV. Flour, water, salt, yeast (2nd experiment). ,, V. Flour, water, salt, yeast, sugar 2 grams. „ VI. Flour, water, salt, yeast, starch 2 grams, gelatinised in portion of the water. ,, VII. Flour, water, salt, yeast, malt flour 1 gram. „ VIII. Flour, water, salt, yeast, starch 2 grams, gelatinised in portion of the water, malt flour 1 gram. BREAD-MAKING. - 477 Gas Evolved. No evolution of gas occurred in Nos. I. and II . Time. Xo. III. Xo. IV. Xo. V. Xo. VI. Xo. VII. Xo. VIII. 0 245 245 0. [350 350 '170: t250 1 ^343 1 Il87 1 hour 170 1 1 1 '240 256 { 1 1 [316 343 1 1 ^440 187 1 1 1 l293 365 610 384 734 2 hours 410 1 572 1490 783 480 1 440 1,050 [416 1 l360 1 1 ^536 1 l342 3 „ 1,150 209 1,359 770 1 1 l380 1,062 1 1 [400 1,319| 1 k75 822 1 1 [360 330 1,380 165 4 „ 1,150| 1 1,462 1 1,794| 1 1,182| [l98 1 ^340 [l85 1 t258 1 [344 5 1,545 1,557 1,490 ^ 1 1,647; 2,052 1 1 1,526 1 125 104 1,661 [330 [l80 1 [268 1 [310 6 ,, 1,670^ 1,820^ 1 1,827' ) 2,320^ 1 1,836^ 1 [ 96 7 „ 1,757 92 8 „ 1,849 176 10 „ 2,025 [l56 12 „ 2,181 109 2,290 14 „ 1 109 16 „ 2,399 106 2,505 ! 104 1 18 „ i 20 „ 2,609^ ! Numbers I. and II. were made up in order to make subsequent tests on the doughs after standing. As would be expected, there was no evolution of gas in either case. No. III. may be compared with a somewhat similar experiment described in paragraph 466. There the conditions were as nearly as possible those of actual practice : it may be taken therefore that the fermentation in this latter case was more than double that which occurs in normal bread-making, being represented by 1,670 c.c. as against 705 c.c. of gas. Nos. III. and IV. are duplicates for the first 6 hours, but in IV., gas was evolved much more vigorously at the start, a result which must be regarded as due to greater initial fermentative power in fresh yeast of another day’s supply. At the end of 6 hours the quantity evolved was practically alike in both cases, 1,670 as against 1,661 c.c. But right up to the close of No. IV. there was a considerable and steady evolution of gas. Nos. V. and VI., respectively containing added sugar and gelatinised starch, gave about the same amount of gas, 1,820 and 1,827 c.c., the maximum production of gas being greater, however, in No. VI. In No. VII., to which malt flour had been added, there was considerably more gas than in any of the other tests, 2,320 c.c. This amount is equivalent to that evolved in No. IV. in about 14 J hours. In No. VIII., which contained both malt 478 THE TECHNOLOGY OF BREAD-MAKING. flour and gelatinised starch, the gas evolved was only about the same as gelatinised starch only, 1,836 as against 1,827 c.c. Analyses of Flour and Dough . — In the flour, the gluten was determined in the usual manner, and dried. The true gluten was estimated by the Kjeldahl process on the dry gluten. The gliadin is that yielded by direct extraction of the w^et gluten from 10 grams of flour, being 2*8 grams. A measured quantity of 100 c.c. of 70 per cent, alcohol was employed. The w’et gluten and 20 grams of w'ashed and dried precipitated chalk w ere placed in a mortar and triturated with a sufficiency of the alcohol to produce a slack dough. The trituration was continued until the whole of the gluten was disintegrated, no visible particles being present. This dough, together w ith the remainder of the alcohol, w as transferred to a flask and vigorously shaken. In every case the sediment w'as carefully examined in order to see that all the gluten had been thoroughly comminuted. The contents of the flask w^ere then raised to the boiling point, and again thoroughly shaken. The flask was then allow'ed to stand over night, shaken up once more in the morning, allow'ed to settle for a few minutes, and filtered. A direct estimation by weight w^as then made by evaporating 50 c.c. of the filtrate and drying off in a tared glass dish. True gluten, less gliadin, w^as then reckoned as glutenin. The soluble extract was obtained by the addition of 500 c.c. of distilled w^ater to 50 grams of the flour, shaking vigorously at intervals during 30 minutes in the cold and then filtering after 5 minutes" subsidence. A sufficient quantity of a turbid filtrate was almost immedi- ately obtained, and this w^as filtered bright on a separate filter. Aliquot parts of this solution w ere taken for the estimation of reducing and non- reducing sugars and soluble proteins. The doughs w^ere first thoroughly mixed and re-kneaded ; 50 grams w'ere then taken, and washed in successive small quantities of tap water (deep w^ell from the chalk), wdth separation of gluten. As 50 grams of dough contain about 21 grams of starch, having a specific gravity of 1*5, the starch present w^as assumed to occupy 14 c.c. The w^ashing w^ater w'as therefore made up to 514 c.c., allowing 500 c.c. of liquid. To this solu- tion, 10 grams of thoroughly washed and dried kieselguhr w'ere then added, and the solution filtered bright. Total soluble matters, sugars, and pro- tein, w ere then determined in the filtrate. The gluten w as weighed in the w et and dry states, and true gluten and gliadin and glutenin estimated as before. The moisture w^as determined direct on a portion of the dough, and the acidity on another portion direct. The dough w^as triturated with distilled w^ater in a mortar and titrated Avith phenolphthalein and A/10 soda, the acidity being calculated as lactic acid. The results of the analyses are given in the following table, both on the flour and dough as examined and as calculated on the w^ater-free solids. The numbers attached to the doughs are the same as before ; the flour is designated No. 0. The moisture in the doughs cannot be regarded as absolutely exact, since there is a difficulty in obtaining a perfectly fair sample : there must also be a slight loss through continued fermentation in the hot-water oven. An examination of these results show^s that a greater quantity of wet gluten was obtained from all the doughs, except No. IV., than was obtained from the flour. In No. IV. there is a very marked diminution. Speaking gener- ally the dry glutens are slightly low^er than in the flour, thus showing that as a result of fermentation the w^ater-retaining powder of the gluten is in- creased. As might be expected, the dry gluten also of No. IV. is much less. The ratios of wet to dry gluten of Nos. 0., I., III., and IV., are as follow’s : 2-70, 3*22, 3*24, 2*85. It will be seen that the w’ater-retaining pOAver of the gluten has receded under the long fermentation of No. IV. to practically BREAD-MAKING. 479 the same as that of the flour. In all the doughs there is a diminution of true gluten. The proportion of protein dissolved from the wet gluten by treatment with 70 per cent, alcohol in the manner described is much less than that obtained by extraction of the flour direct by the methods usually Composition of Flour and Doughs. Constituents. Xo. 0. No. I. No. II. As Exd. Water Free. As Exd. 1 Water Free. As Exd. Water Free. Moisture 14-27 42-11 i 41-99 Gluten, Wet.. 28-05 32 72 20-40 35-29 20-70 35-40 „ Dry 10-50 12-14 6-34 10-97 6-50 IMl „ True 8-87 10-33 5-31 9-19 5-84 9-99 Gliadin ex gluten . . 2-20 2:80 2-28 3-91 2-07 3-54 ,, per cent, of True Gluten . . — 27-04 — 42-54 — 35-43 Glutenin ex gluten . . 6-67 7-53 3-05 5-28 3-77 6-45 Soluble Extract 4-04 4-71 4-07 7-04 5-91 10-11 ,, Protein 1-24 1-45 0-34 0-59 0-40 0-69 Reducing Sugars 1-09 1-27 0-63 1-15 0-47 0-80 Non-reducing Sugars 0-16 0-19 1-54 2-67 2-56 4-38 Acidity as Lactic Acid — — — — 0-084 0-144 - No. III. No. IV. No. V. Moisture '43-65 44-49 1 44-55 Gluten, Wet.. 20-3 35-93 13-78 24-80 19-92 35-86 ,, Dry ' 6-28 11-08 4-84 8-71 6-10 10-98 ,, True 5-73 10-14 4-29 7-72 5-25 9-45 Gliadin ex gluten . . 1-81 3-20 M7 2-10 1-74 3-13 ,, per cent, of True Gluten . . — 31-55 — 27-21 — 33-12 Glutenin ex gluten . . . . 3-92 6-94 3-11 5-60 3-51 6-32 Soluble Extract . . . . i 3-81 6-73 3-97 7-14 3-50 6-30 ,, Protein 0-50 0-88 0-55 0-98 0-40 0-72 Reducing Sugars 0-04 0-07 0-40 0-72 0-20 0-36 Non-reducing Sugars 0-58 1-02 0-33 0-60 0-35 0-63 Acidity as Lactic Acid 0-09 0-159 0-09 0-162 0-09 0-162 No. VI. No. VII. No. VIII. Moisture 43-68 — 44-35 — 43-28 Gluten, Wet.. .. ' 19-16 33-91 19-20 34-56 19-88 34-99 ,, I)ry 6-02 10-97 5-91 10-64 6-01 10-58 ,, True . . . . 5-40 9-56 5-34 9-61 5-41 9-52 Gliadin ex gluten . . 1-94 3-43 1-96 3-53 2-14 3-77 ,, per cent, of True ; Gluten . . . . — 35-87 — 36-73 . — . 39-60 Glutenin ex gluten . . . . 3-46 6-12 3-38 6-08 3-27 5-75 Soluble Extract . . . . 4-28 7-57 4-63 8-33 4-94 8-69 ,, Protein . . . . 0-40 0-71 0-34 0-61 0-40 0-70 Reducing Sugars . . 0-35 0-62 0-86 1-55 0-51 0-90 Non-reducing Sugars 0-54 0-95 0-74 1-33 0-67 1-18 Acidity as Lactic Aci \ 0-09 0-159 0-09 0-162 0-09 0-158 1 4e0 THE TECHNOLOGY OF BREAD-MAKING. r.dopted. These results are therefore not comparable with those of ghadin\ ex flour, but may be compared among themselves. The most instructive comparison is probably that of the various percentages of gliadin in true gluten with each other. Of the flour true gluten, 27*04 per cent, was thus dissolved. In the dough treated with salt. No. II., this figure had increased to 42*54, while in No. III. it was also high. In No. III. there is an increase of the soluble gluten over that in the flour, while with the over-fermentation of No. IV. the soluble portion of the gluten has diminished. A possible explanation of this is that in washing this long-acted-on gluten some of the gliadin is lost by washing away. In all the glutens from the more normally fermented doughs, there is an increase in the proportion which is soluble. (It is shown in paragraph 851, that chalk removes some of the gliadin from solution by adsorption. These gliadin results are therefore too- low, but are nevertheless comparable among themselves.) In the soluble extracts, that of the flour is 4*71, a figure materially increased in the- salt made dough : it is very probable this would have been more in a dough made from flour and water only. The addition of malt flour, as might be expected, caused a still further increase in the amount of soluble matter present. The malt flour used had a diastatic capacity of 48*6° Lintner, and 31*93° when tested with ordinary starch solution instead of that of soluble starch. Although in all the fermentation tests there was a destruction of some of the soluble matter by the yeast, yet that remaining is more than the soluble matter of the flour itself. In every case there is much less soluble protein obtained from the doughs than from the original flour. The reducing sugars are calculated as maltose from the cupric reducing power of the solutions in each case. It is difficult to see why this should have been less in Nos. II. and III., but still the fact remains. In the fermented doughs, hydrolysis of starch and fermentation of sugar are proceeding together, and except in No. VII., the combined causes have caused a diminution in the reducing sugars. The solutions were in eAl cases inverted in the ordinary manner by the addition of hydrochloric acid and heating to 68° C. The consequent increased cupric reducing power was ascribed to the presence of cane sugar and calculated as such. Here again there are some anomalies, as the flour yielded only 0*19 per cent, of non-reducing sugar. Under the influence of salt, No. I., and salt and malt. No. II., this figure increased in these doughs to 2*67 and 4*38- respectively. This treatment can scarcely be expected to have actually resulted in the production of cane sugar. It is suggested as a possible- explanation that the soluble extract may have consisted in part of soluble starch or some of the higher and unstable dextrins, and that these were converted into maltose by the hydrochloric acid, and hence the considerable- increase in cupric reducing power. In the case of all the fermented doughs, there is an increase in the non-reducing sugars, determined in the same man- ner. The acidity results are rather surprising, as in all, including the very long fermentation. No. IV., the quantity obtained is practically the same. Further Data on Doughs . — With the aid of the preceding tables some further data may now be given of these doughs. These follow and are mostly self-explanatory. The weighs of raw materials are given, and also that of the dough, showing the loss incurred in making. The loss in fer- mentation is that obtained by direct weighing before and after. The vol- ume of gas was that read off in c.c. in each experiment. This was converted into grams by multiplying by the factor, 0*00185. As 100 grams of sugar are required for the production of 46*4 grams of carbon dioxide, the number of c.c. of gas, multiplied by the factor 0*004, gives the weight of sugar re- quired for its production. The alcohol produced may be taken as about one-half the sugar required. The figures obtained in this manner must be Various Data of Doughs. BREAD-MAKING. 481 o o 7 CO o o X 7 CM c:: »o 7 7 I-H CO lo X CM Hh CO CM C5 o CO CO CO CO CO CM X O 7 9 9 9 9 7 7 fiH > i3- c^ 00 CO a lo CX) CO I:- CO r-l 9 cb CM 6 7 cb P COl cb eo O tH lO 7 C5 (M lO o CO 7 o iM uo ©O CM CO CO X lO I-H O I-H -H 00 o CO lo Ci 7 ex 7 o 9 9 X 7 CM CM 9 CM CO CM 9 9 t2 0^1 CO CO lO 7 X 7 p-i 9 cb cb 6 7 A 9 A 7 ob d O Tin lo 7 CTi cm" CM o o o O o X UO CM C3i uo CO X CM eo lO I-H CO o ©O 1-- CM CM CC^ CO CO CO CM o CM 7 I-H CM 9 X 7 ex 9 P CM r^ CM (M 1^ CO cb p cb P rd CM CM 6 7 cb O CM COl 7 lo 'd lO 7 O CM 1 o o o O o o X 7 7 X CM X 7 O cc> CO X X eo CO lO CO 7 i-H 00 (M ao^ X CM CO CM COl 9 7 O 9 op CO 7 9 1-- 1:2 Ol ,-H CO CO cb CO 1— 1 rd 1 p COl p-H c:^! 6 6 6 6 6 6 6 6 6 CO 7 cb o o 6 P O 7 lO 7 C05 CM -(d ■7 • d d d • © ccT 7 © © © © 0 © • s s • g s S cj S-. &£) C C ^ O • fl O CD .3 — I m CD ^ W o B u g 03 ® s bc bCTJ •g| '3 §11 © 3d _ ©j • 9 S •t-t • 2 3D d eg 9 0 O r— I H P 0 g cc ^ 2 0 "o ’ ©H P ' o ^ ©3 2 9 .3 ^ '-M 'S) 0 r2 ^ ^ 73 "o ►> 'o _ 'Mr^ oO M > O 0 XTl M ^ CS 0 ^ ^ 0 .2" bC bC^ 73 ^ O O S tfH ^ 2 M ;_, O 1 -S O H ^ o 1 8| §5ls^ ^ Q h:] > ^ 3-40 6-39 ( )ther Soluble Matters 6-15 11-80 12-22 23-06 20-03 29-81 1-78 3-35 Phosphoric Acid . . 0-43 0-83 0-56 1 02 0-41 0-61 0-39 0-74 Other Mineral Matter 0-60 1-13 0-72 1-31 0-59 0-87 0-53 0-99 j Acidity as LacticAcid 0-43i 0-82 0-40 0-72 0-51 0-75 0-50 0-95 Fat 1 -30l 2-49 1-20 2-00 0-25 0-37 0-60 1-13 Energv in Calories 1 214-7 i i — 239-0 ■ — “ i 304-3 — 215-3 1 CHAPTER XX WHEAT, FLOUR, AND BREAD IMPROVERS. 624. Agricultural Improvement of Wheat. — Among the various endea- vours made to improve the quality of bread as a food, the first in order of natural sequence are those directed to the improvement of the wheat itself. Conspicuous among these is the work of the Home-grown Wheat Com- mittee of the National Association of British and Irish Millers, which for some years has devoted itself to the improvement of English wheat. Credit for such patriotic work is largely due to Humphries, Biffen, and Wood, by whom most of the requisite extensive researches have been conducted. English wheats had been deteriorating in strength, and to remedy this defect experi- ments were made in the direction of selection of seed, and hybridisation, in order to secure stronger varieties. As necessary factors in strength a sufficiency of gluten, and of gluten of good quality, are required. Wood's most recent investigations go to show that strength is associated with the presence of certain mineral salts in the grain, the principal of which is a relatively high percentage of water-soluble phosphates. If this should be completely demonstrated, the obvious course will be first to secure a suffi- ciency of soluble phosphates in the soil ; and then to use as seed wheats those which have a natural selective preference for such phosphates. By cross-breeding and careful selection it may also be possible to induce their absorption by other varieties of the grain. 625. Treatment of Wheat by Water-soluble Phosphates, Chitty and Jago. — This subject has been approached by the above-named investigators, who have been granted a patent. No. 22,434, 1909, for a process of treating wheat by soaking the grain in a solution of phosphoric acid or other soluble phos- phates. In their specification, the patentees state that a very marked improvement is thus effected in certain wheats mentioned. Such treat- ment specially increases the strength of the wheats. It would seem, there- fore, that not only are wheats favourably affected by a naturally high water- soluble phosphate content, but they are also similarly improved by the addition of such phosphates in appropriate form to the grain. 626. Application of Moist Heat to Grain and Flour, Simon. — In 1908, a patent was granted to Henry Simon, Ltd., No. 9,946, for improvements in conditioning flour by treatment with moisture-laden air. One of the objects of the invention is the replacement of such natural moisture of the wheat as is removed during the operations of milling. Air is raised in temperature by passage through heated pipes and then conducted into a chamber in which water is being sprayed. The hot air is thus charged with moisture, and is next led into the fully milled flour as it passes through an apparatus in which it is kept in a state of agitation. The proportion of water in the flour is thus increased by OT per cent, or more according to requirements. It is claimed that at the same time the flour is conditioned, that is, is improved in its baking qualities. As flour may easily vary in moisture content within a range of as much as I -0 per cent, as the result of the relative dryness or humidity of the atmosphere, it is difficult to see 498 THE TECHNOLOGY OF BREAD-MAKING. where an increase of OT per cent, of moisture, qua moisture, can effect any material improvement in the flour. Investigation by the authors has shown, however, that with certain flours improvement in baking qualities does, as a matter of fact, follow the treatment. The suggestion is made that it is the heat, together with the moisture, by which the improvement is effected. 627. Spraying Treatment of Wheaten Stock and Flour, Humphries. — In June, 1908, an application. No. 13,135, was made for a patent by Hum- phries for an invention essentially consisting of the introduction of various ingredients into flour in the form of a very finely divided spray. The patentee prefers, however to apply his spray to stock, as during the subse- quent stages of milling it is then more thoroughly mixed with the flour. When the stock is thus sprayed, even with water alone, there is stated to be an improvement in the colour of the flour. During the spraying opera- tion the flour or stock require to be kept in motion by some suitable appliance. Not only may water be thus introduced, but other beneficial ingredients either dissolved or finely suspended in the water may be added. Among the substances thus capable of introduction, the patentee suggests the following : — (а) Yeast foods. — For example an aqueous solution of diastase, contain- ing diastase equal to about 0-02 per cent, of the flour, or solutions of maltose and dextrin, or of nitrogenous yeast foods. (б) Substances affecting 'physical characteristics of the flour. — These im- prove the dough, and may consist of solutions of appropriate mineral salts u,s those of potassium, calcium or magnesium, or an acid such as phosphoric u^cid. (c) Retarding agents. — These may be used for checking fermentation ■or excessive effect of enzymes, so as to improve stability. Examples are a dilute solution of potassium carbonate, or a solution of common salt, or the like. Formulae are given of quantities, and best mode of applying these various reagents. The application for this patent was the result of a prolonged investiga- tion of the conditions affecting the quality of wheaten flour. The starting- point was the discovery that the soluble matters of bran were found capable ■of improving such flour. A water extract of bran contains mineral salts, among which are phosphates of lime, magnesia, and potash, and in smaller quantities sulphates and chlorides. In addition there are sugar and pro- teins, the latter possessing considerable diastatic activity. With the wide variations in the characteristics of different wheats, it was found that a selection from among these was necessary in order to obtain the greatest improvement possible with each variety. Thus with those deficient in sugar, an addition of saccharine constituents is obviously indicated. In Humphries’ opinion, some wheats are not only deficient in ready-formed sugars, but also in sufficient diastase to produce such sugar as is necessary during fermentation ; here the introduction of some diastatic body is ■desirable. With certain peculiarly hard and intractable glutens, he regards the addition of suitable enzymes as being of considerable service. Where, on the other ‘hand, these enzymes are naturally in excess, with a tendency of the gluten to become runny, some retarding agent is of advantage. Among these are such substances as common salt and potash, either in the form of hydroxide or carbonate. In whichever form added, the carbon dioxide of fermentation causes the resultant body to be a carbonate. Again, Wood has shown that a serious defect of certain wheats is the deficiency of certain mineral salts, and this may be remedied by adding appropriate salts such as those of potassium, calcium, or magnesium. As a stimulant WHEAT, ELOUR, AND BREAD IMPROVERS. 499 to yeast action, such a body as ammonium phosphate is at times particularly useful either by itself or in combination with malt extract. The result is a good fermentation from flours made from wheats which have been grown in very hot dry conditions of atmosphere and soil. Humphries also insists on the importance of affecting the physical condition of flour, even by the use of water only, so that the natural or added ferments may operate to maximum advantage in panary fermentation. In other cases he would reduce the percentage of water in wheat before grinding with the same object. In the application of these various reagents, Humphries prefers the employment of their solution in the form of spray, as thereby an exceedingly intimate admixture of the substances with the flour is obtained. For the same reason he prefers to make the addition in the earlier intermediate stages of milling; as the following grinding processes serve to effect a very close combination with the flour. As to the effect of the water itself, employed as a carrier of the different substances used in the spray, Humphries in the first place insists that only a very small proportion is needed or desirable, and certainly no such amount as seriously increases the water content of the flour. This, he finds, will, ■enable the pressure on the rolls during grinding to be considerably dimin- ished, and consequently the temperature of the ground stock is substantially lessened. With this reduction in temperature, the amount of moisture given off in grinding is decreased, and the subsequent condensation or “ sweat- ing inside roller mills and dressing machines, and “ pasting up of silks is much diminished or entirely abolished. It is a well-known and practically necessary practice in milling to condition hard wheats by the addition of water, and Humphries believes such addition in certain cases to be prefer- able after the removal of the germ and the bran, as thereby the percentage of unstable products introduced into the flour from these bodies is reduced. Finally, he submits that the materials added to the flour are desirable food- stuffs, and such as are themselves natural to wheat, flour or bread. On behalf of the German Patent Office, an official investigation of the Humphries’ process has been made, whose report has been placed at the disposal of the authors. They regard the process as of great value, and state that their baking tests show a greater elasticity of the dough in the case ■of the treated flours, which they regard as a material improvement. In addition to this, there is a better browning of the crust and a very large increase in the volume of the bread. 628. Flour Improvers, Manufacture of Phosphates. — Under this name may be included any preparations offered to or used by the miller for the treatment of flour, as distinct from processes such as already described. The principal substance of this type is the acid phosphate of calcium, in addition to which there are other soluble phosphates. Being white powders, these bodies do not injuriously affect the colour of the flour. In view of the circulation of certain recklessly inaccurate statements as to the source and mode of manufacture of phosphates, it has been thought well to place a definite description of same on record. Bones consist largely of calcium phosphate and carbonate together with a certain amount of organic matter. On the addition of the requisite amount of sulphuric acid to ground bones the phosphate is converted into the soluble form thus: — Ca3(P04)3 + 2 HBO 4 = CaH4(P04). + 2CaS04. Calcium Sulphuric Calcium Calcium Phosphate. Acid. Hydric Phosphate Sulphate. (Superphosphate ). It will be noticed that the sulphuric acid as such has entirely disappeared, having been converted into the sulphate. For manurial purposes, bones are 500 THE TECHNOLOGY OF BREAD-MAKING. treated in this manner, and the whole mixture offered as “ dissolved bones or “ vitriolised bones."" This preparation is very valuable for the purpose for which it is intended ; but, in common with many other manures, possesses such an objectionable smell and taste as to render it absolutely impossible as a constituent of food. For food and medicinal purposes, the principal source from which Great Britain derives its raw material for the manufacture of phosphorus com- pounds is the cattle-raising districts of South America. The bones from the slaughtered carcases are first treated for the extraction of glue, after which the mineral matter is burned or calcined at a white heat, and to a white ash, known as bone ash. This consists of the before-mentioned phosphates, and lime from the carbonates, and is free from organic matter. After importation the ash is treated with arsenic -free sulphuric acid, manufac- tured from sulphur as distinct from pyrites. The phosphate undergoes the same change as before described, with the total disappearance of any free sulphuric acid. The soluble phosphate is then separated more or less com- pletely from the calcium sulphate ; or for the cheaper grades the two are sold together, hence the high percentage of calcium sulphate in the low grade phosphates. An article of a high degree of purity is obtained by treating the bone ash with phosphoric acid instead of sulphuric acid. The change then becomes : — Ca3(P04)2 + 4 H 3 PO 4 = 3CaH4(P04)2. Calciuni Phosp'ioric Calcium Hydric Phosphate. Phosphate. Acid. (Acid Phosphate). Tlie phosplioric acid may be prepared by burning phosphorus in air in the presence of water, or by treatment of bone ash with sufficient sulphuric acid to convert the whole of the lime into calcium sulphate. By the use of properly made phosphoric acid it is possible to obtain a phosphate which may be sold under a guarantee of freedom from arsenic, and as containing not more than 2 per cent, of calcium sulphate. Bakers are strongly recom- mended to insist on the supply of phosphate of this degree of purity, and to refuse acceptance of any lower quality. With the view of increasing the diastase of the flour, it has been pro- posed to add small quantities of highly diastatic malt flour. Unless very finely dressed such a preparation will cause the flour to look “ specky."" 629. Chemical Changes produced in Flour by Bleaching, Monier- Williams. — • A note was inserted at the end of Chapter XVII., page 399, to the effect that reports on flour bleaching and flour improvers had been published by the Local Government Board. As most of the book was then in type, it was only found possible to arrange for a reference to these reports in this place. An extended experimental investigation was conducted by Monier- Williams. A summary of his more important conclusions follows : — • “ Summary of Results. The action of air containing nitrogen peroxide upon flour, in quantities up to 300 c.c. of nitrogen peroxide to one kilogram of flour, may be summar- ised as follows : — I. The golden-yellow tint of the flour is destroyed. Immediately after bleaching no difference in tint due to excess of the bleaching agent could be observed with Lovibond’s tintometer, but on keeping for several days the more highly bleached samples became decidedly yellow, while those treated with 30 to 100 c.c. of nitrogen peroxide per kilogram became still whiter, the maximum of bleaching effect being attained within these limits. II. The amount of nitrous acid or nitrites present in a freshly bleached WHEAT, ELOUE, AND BREAD IMPROVERS. 501 flour is approximately proportional to the amount of nitrogen peroxide employed, and eorresponds to about 30 per cent, of the total nitrogen ab- sorbed, rising to 40 per cent, in the more highly bleached samples. After the lapse of several days, the proportion of nitrites present decreases con- siderably in the higher concentrations, but remains very nearlj^ the same in the more slightly bleached samples. III. Approximately 60 per cent, of the total nitrogen introduced as nitrogen peroxide into the flour during bleaching can be recovered as am- monia a short time after bleaching by reducing the aqueous extract of the flour with a copper-zinc couple, and may be assumed to be present in the flour as nitric and nitrous acids or as nitrates and nitrites. After keep- ing the bleached flour for some days the amount of nitric acid extracted with cold water decreases. Experiments with pure glutenin and gliadin indicated that in certain circumstances nitric acid may be withdrawn from solution or ‘ adsorbed ’ by these proteins. IV. In highly bleached flour a considerable increase in the amounts of soluble proteins and soluble carbohydrates takes place. If one kilogram of flour is bleached with 300 c.c. of nitrogen peroxide, the amount of soluble nitrogen is doubled. This appears to be due almost entirely to the solu- bility of gliadin in nitric acid of certain concentrations. The simultaneous increase of soluble carbohydrates would seem to point to an intimate relation- ship between the gliadin and certain carbohydrates in flour. V. If highly bleached flour is allowed to stand for some time after bleaching, the oil undergoes very considerable alteration and acquires the characteristics of an oxidised oil. About 6 to 7 per cent, of the nitrogen introduced as nitrogen peroxide during bleaching is absorbed by the oil. VI. The absorption of nitrogen peroxide by flour does not appear to be accompanied by I the production of free nitrogen, nor was any evidence obtained of the formation of diazo-compounds. VII. Sodium nitrite was found to exert no inhibitory action on the digestion of soluble starch by saliva, but the rate of digestion was greatly retarded if the starch had been previously treated with nitrogen peroxide gas. Bleaching was found to exercise an inhibitory effect on the salivary digestion of flour.” {Reports to Local Government Boards New Series, No. 49, April, 1911). I ! The above report may be very profitably compared with the results of Snyder’s investigations, paragraph 518. It will be noticed that Snyder made his digestion experiments on human subjects with bread from un- bleached and bleached flours, whereas Monier- Williams made artificial digestion tests with the respective flours. 630. Flour Bleaching and “Inproving,” Hamill. — In response to instructions from the Local Government Board, Hamill has inquired into the practices of flour bleaching, and the adding thereto of improvers, and has made a report to the Board of which the following are the principal conclusions. Various methods of treatment of flour on these lines are described in detail, including nitrogen peroxide and ozone bleaching pro- cesses. He then goes on to state that — “ Flour has also been treated with sulphuryl chloride, sulphur trioxide and chlorine, and other similar mixtures, but I am informed that the results have not been encouraging. Sulphuryl chloride is stated to improve the strength of flour, but the sulphur trioxide and chlorine mixture is uncertain in action, and is usually without any beneficial effect on the baking qualities of flour. In practice the odour which these substances impart to the flour precludes their use as ‘ improvers.’ In some recent patents it is proposed to treat flour with phosphorus 502 THE TECHNOLOGY OF BREAD-MAIvING. trichloride, pentachloride or other halogen compounds of phosphorus, or with a mixture of these and sulphur trioxide, nitric acid, nitrous acid, iodic or other halogen acids ; also formic, acetic, propionic or benzoic acids, alcohol, aldehydes, or ketones, with the object of strengthening the flour and improving its baking qualities. It has further been proposed to treat flour with phosphorus pentoxide, phosphorus bisulphide, and phosphorus pentasulphide, and the process has been patented. Although much experimentation of an empirical kind is proceeding, in the course of which a variety of heterogeneous substances may be added to flour, it may be said that apart from nitrogen peroxide the only substances whose use as yet has been attended with any measure of commercial success are certain acids and salts, more particularly phosphoric acid and phos- phates.” In summarising the effects of both bleaching and the use of improvers, Hamill goes over much of the ground already dealt with in the seventeenth and present chapters. Omitting these matters of history the following are his most important conclusions : — ■ “ Bleaching and so-called Flour ‘ Improving ’ in relation to Public Health and the General Interests of the Consumer. Bleaching hy Nitrogen Peroxide. Dr. Harden shows that under the conditions in which his experiments were conducted no obvious effects were produced on animals fed with highly bleached flour or with aqueous extracts of such flour. Dr. Harden’s report also contains an account of experiments in regard to peptic and pancreatic digestion of bleached and unbleached flour ; and Dr. Monier-Williams gives corresponding results with salivary digestion. From these it appears that bleaching has a distinctly inhibitory effect on peptic digestion, but no observable effect on the pancreatic (proteolytic) digestion of flour. Sodium nitrite was found to exert no inhibitory effect on the salivary digestion of starch, but in the case of starch treated with nitrogen peroxide, digestion was greatly retarded. Bleaching was also found to exercise an inhibitory effect on the salivary digestion of flour. As regards the action of nitrites on the system, it should be remembered that nitrites when administered as drugs, produce various effects, amongst which disturbance of the heart and vascular system are prominent. The amounts of nitrite introduced by bleached flour would be of a much lower order than those taken when nitrites are given medicinally.^ Statements have been made, however, by medical practitioners that an appreciable effect may be produced by quite small doses of nitrite : Gustav Mann points out that quantities such as half a grain (32 milligrams) of nitrous acid may be harmful to some individuals. What may be the physiological or pathological effect of ingestion of even smaller doses when taken day by day throughout many months or years it is impossible to say ; there is no evidence on the matter, and it would be very difflcult to obtain any. It cannot, however, be regarded as desirable that minute doses should be in- gested day by day of a drug which in larger single doses has a marked action on the vascular system. It would appear from experimental and other considerations to which reference has already been made, that, apart from the addition of nitrites, the constitution of flour may be altered by bleaching. Dr. Monier-Wil- liams has clearly shown in his report that the oil of flour undergoes a marked change : it has been suggested by Folin that nitration of the flour oil, if ‘The phariTiacopoeial dose of sodium nitrite is 1 to 2 grains, and of nitro-glycerin (in Liquor Trinitrini) to -Aj grain. WHEAT, FLOUR, AND BREAD IMPROVERS. 503 it occurs, might entail risk to health, since absorption of the oil and its oxidation in the tissue might occur, resulting in the liberation of nitrites. Ozone produced together with nitrogen peroxide in certain bleaching pro- cesses also exerts a markedly destructive action on olein, one of the constitu- ents of flour oil. In sj^ite of assertions to the contrary there seems to be evidence pointing to the possibility of the protein constituents of flour being adversely affected as the result of bleaching. Dr. Monier- Williams has shown that the solubility of the proteins and also of the carbohydrates is increased by such treatment. These changes in the oil, the protein and the carbohydrates are, of course, more marked when flour is overbleached, and though over bleaching is not likely nowadays to occur throughout the whole of the flour, local overbleaching may take place, portions of flour adhering to the sides of the agitator and flour spouts may become overbleached and contaminate to some extent, at any rate, the rest of the flour. Looking to the above considerations, it may be concluded that the alterations in, and the additions to, flour which result from a high degree of bleaching by nitrogen peroxide cannot be regarded as free from risk to the consumer, especially when regard is had to the inhibitory effect of the bleach- ing agent on digestive processes and enzymes. Even in the case of flour which is bleached to the small extent which is at present ordinarily prac- tised, it would in present knowledge be unwise to conclude that the process is attended by absolute freedom from risk. The fact that bleached flour has been shown to be something more than natural flour, the colour of which has been modifled, is also of importance in considering whether bleached flour may properly be represented as genuine flour. The practice of bleaching being open to these objections, it remains to inquire whether the consumer, who at present is seldom aware that his flour has been bleached, or that his bread is made from bleached flour, can bo said to obtain any compensating benefit. To this a negative answer must be given. Apart from any dietetic considerations a large number of people desire bread of exceptional whiteness, and it is reasonable to suppose that what is demanded by those who prefer such bread is an article made from flour, the whiteness of which is due to its being prepared from specially selected wheats by the elaborate mechanical separation and ‘ purification ’ of modern milling methods. Few people would carry their approval of white- ness to the extent of requiring naturally dark flour to be chemically treated. So-called ‘ Flour Improvers.’’ Many of the above considerations apply also to the addition of ‘improvers" to flour. These articles can hardly be regarded as proper constituents of what is represented to be genuine flour in this country. Those interested in these preparations advocate their use on the grounds that they add nothing to the flour that is not normally present therein, and that they increase the lightness and improve the quality and appear- ance of the loaf, and also permit of more loaves being made from a given quantity of flour. The first of these contentions is based on the assumption that phosphorus in flour is present in the form of phosphate, chiefly potas- sium phosphate. This is not so ; it is true only of the ash of flour. A large portion of the phosphorus in flour is present in organic combination, and experimental evidence exists which would seem to indicate that phosphorus in this form may possess a dietetic value quite different from inorganically combined phosphorus. This is recognised by certain millers, and it is sug- gested that such organic phosphorus compounds may be formed when solu- tions containing phosphates are intimately mixed with flour in the form of a fine spray from an ‘ atomiser.’ No evidence is adduced in favour of this 504 THE TECHNOLOGY OF BREAD-MAKING. contention, and it may suffice to say that the formation of complex organic phosphorus compounds in this way is contrary to experience. The second advantage claimed, namely, the increased loaf production from a given quantity of flour, is one which will appeal only to the miller and baker. The gain in production is due to the increased amount of water which the flour absorbs and to the increase in volume of the dough, resulting from the improved elasticity of the gluten. This naturally means a diminution in the actual amount of flour in each loaf, and, consequently, in nutritive value, so that the consumer in this respect loses by the treat- ment. The protein content of flour is an important matter from the standpoint of nutrition, especially where bread enters largely into a diet. Flour from weak wheats, which are generally poor in gluten, contains less protein than flour from strong wheats which are rich in gluten. But by the use of ‘ im- provers ’ flour from weak wheat is made to simulate flour from a stronger wheat, although as regards protein content it is inferior to the flour which it imitates. With regard to other substances which have been represented as ‘ im- provers,’ it may be said that the indiscriminate addition of powerful chemical substances such as hydrofluoric acid, phosphorus pentachloride, and the oxides and sulphides of phosphorus to flour is most dangerous. The increasing activity which is now being displayed in the use of dif- ferent articles as additions to flour must be regarded with considerable apprehension. It does not appear desirable that such an indispensable foodstuff as flour, the purity and wholesomeness of which are of first im- portance to the community, should be manipulated and treated with foreign substances, the utility of which, from the point of view of the consumer, is more than questionable.” {Report to Local Government Board, New Series, No. 49, April, 1911). The authors are prevented by exigencies of time and space from giving this report the detailed examination it merits ; they therefore suggest as with that of Monier- Williams its careful comparison with Snyder’s bulletin, summarised in paragraph 518. Hamill and Monier- Williams have appar- ently finally disposed of the statements that the extract of bleached flour is violently poisonous to animals ; they also find no evidence of the presence of diazo-compounds. In considering Hamill’s remarks on the physio- logical or pathological effect of continual minute doses of nitrite, it is well to bear in mind the actual amounts ingested : on page 384 of this book it is pointed out on the authority of Wesener and Teller that in order to take the maximum safe dose of nitrite (3 grains) by eating the bread from bleached flour, 10,000 one pound loaves would have to be eaten, and that at the average rate of bread consumption, an individual who commenced the day he was born would be 55 years old before he would thus have taken a single medicinal dose of nitrogen trioxide. Flour is one of those articles of food which are never eaten in the raw state, and Snyder states categorically that the bleaching gas is expelled from flour in all the various ways in which it is prepared for food. He points out that bread made from bleached flours and baked out of contact with combustion of gases gives no reaction for nitrites, whereas bread made from unbleached flour and baked in an ordinary gas oven shows appreciable amounts of nitrites formed from combustion of the gas. He then asserts that “ since the material used in the bleaching of flour is expelled in the preparation of the food, there remains no question for physiological consideration.” Under these circumstances, it is unfor- tunate that the reports under examination deal only with flour, and not with the resultant bread. In the last two paragraphs of that part of the report which deal with WHEAT, ELOUR, AND BREAD IMPROVERS. 505 flour bleaching, the effect on the consumer is dealt with, and he is said to obtain no compensating benefit. But this runs counter to general experi- ence ; as Hamill says “ a large number of people desire bread of exceptional whiteness.” This being the case, any process which tends to increase the supply of white flour or widen the sources from which it is obtained must necessarily ultimately result in lowering the price to the consumer. For example the mechanical improvements in milling have, by the removal of dirt, materially increased the whiteness of flour. As a consequence the seconds or households quality of bread, sold at seconds price, is now better in colour than was the best bread at the best price of twenty years ago. The miller of to-day works on a finer margin of profit than did his prede- cessor, and the consumer has reaped the full advantage of the various im- provements in modern milling. If from a dark flour, such as that from Walla Walla or Durum wheat, a dark loaf is naturally obtained, and there is an absolutely harmless process by which it can be made into a white loaf, then the authors incline to the opinion that very few of those persons who prefer whiteness would object to its treatment. This is borne out by analogies drawn from other articles of food. Loaf sugar is naturally of a yellow cast, and this is corrected in manufacture by the addition of ultramarine or other blue. Yet the public do not make the slightest objection to the white- ness of sugar being obtained by chemical treatment. In milk the public taste runs in the opposite direction ; the natural white colour of milk is dis- liked, and a yellow tint preferred. The consumer not merely tolerates the addition of colouring matter, but rejects white milk and insists on its being yellow ; in many cases, even when he or she knows quite well how the yellow- ness is produced. So-called “ Flour Improvers ^ — The report first deals with the proposed addition of mineral phosphates to flour, and points out that “ a large portion of the phosphorus in flour is present in organic combination ” — this is an- other way of saying that a small portion is present in the inorganic form. This small portion of mineral phosphate exercises however a most profound influence over the whole quality of the flour for bread-making purposes. Proof of this is afforded by the fact that to flours which are deficient in certain baking qualities, the addition of what is the merest trace of certain mineral salts exercises a most remarkable improving effect. These additions con- sist of mineral constituents which are normally present in wheat, and which usually are relatively deficient in the flour improved by their addition. The fact that such additions result in marked improvement does not admit of doubt. The next question raised is that of increased loaf production from a given quantity of flour, which of necessity means a diminution in the actual amount of flour in each loaf and, according to the report, a diminution in nutritive value, a consequence of which is “ that the consumer in this respect loses by the treatment.” This is an important issue, and requires to be fairly faced and examined. It is, however, of far wider importance than the mere addition of “ improvers ” to flour. Native English wheats are as a whole extremely weak in character ; that is to say, their flours possess a low protein content, low water absorbing power, and produce small close loaves. Because of these properties they are only used to a small extent and com- mand a comparatively low price. The Home Grown Wheat Committee has been and is devoting its attention to the improvement of English wheats. Assuming their efforts to be successful, the line of improvement will be partly in the direction of an increase in the protein or gluten content, but also largely in that of raising the quality of the gluten itself, and thereby increas- ing the strength of the wheat. In so far as the committee succeeds it will have developed and augmented one of our most valuable national assets ; 506 THE TECHNOLOGY OF BREAD-MAKING. but if it does this, the result will be that a weak wheat will liave been made to simulate a stronger wheat although as regards protein content it is inferior to that which it imitates. The improvement of home grown wheat itself ; and also subsequently that of flour therefrom, will be secured by the attainment of the same ends (and probably largely by the same means, viz., that of modifying their mineral content), and both must stand acquitted or condemned by the same judgment. The logical outcome of the suggestion in the report is that the growth , improvement, and consequently increased use of English wheats, should so far as possible be discouraged, because of their inferiority in protein content. In so far as weakness is due to quality rather than quantity of gluten, any improvement which causes flour from the same wheat, or the same type of wheat, to yield bolder loaves and of better texture, whether by alteration of the mineral con- tent or the use of a more vigorous yeast, will at the same time increase the water-absorbing capacity of the flour, since both to some extent go hand in hand. But it does not quite follow that the consumer thereby loses. Everything else being equal, a bold well-risen loaf is more digestible than a small and clammy one from the same flour. It may therefore well be that the greater digestibility may more than compensate for the slightly less flour in the loaf as a result of the increase in water-absorbing power. In these matters it is far better to argue from actual data rather than mere generalities, amd accordingly the following experiments were made : — An ‘‘ improver ” was selected of purely mineral and inorganic origin, and this was added to the flour in the proportion of I oz. to the sack. This amounts to 1 part to 4480, or 0-022 per cent. The proportion in bread is naturally less, being an addition of about 0-014 per cent, of mineral matter natural to wheat, and occurring in several times the quantity in many excel- lent drinking waters. Neither in the mode of manufacture, nor in the nature of its residuum, could there be a suggestion of anything but absolute liarmlessness in the particular improver employed. Loaves were baked from various flours with and without the improver ; in boldness of volume and appearance and texture of crumb, the treated loaves were judged by millers as showing an improvement equal to from Is. to D. 6d. in the com- mercial value of the flour. The first test was made with an all-English flour, the following quan- tities being taken : A, 560 grams flour, 7 grams salt, 10 grams yeast, and 280 grams water. B consisted of the flour treated at the rate of I oz. per sack, but in all other respects the same. The loaves were baked in tins of the same size, and were of the following greatest height : A, untreated, 13-3 centimetres ; B, treated, 16-0 centimetres. The volumes would be in the same relative proportions as the heights. On analysis, the breads gave the figures quoted below. Both were sub- jected to comparative digestion tests in which 50 grams of the bread were treated, at body temperedure, with a slightly acid solution of Armour’s stand- p.rd pepsin (artificial gastric juice), and afterwards with a slightly alkaline solution of Armour’s standard pancreatin (artificial pancreatic juice). The resultant mass was filtered, and proteins determined in the filtrate. A correct- ion was made for the quantity present in the reagents used. The following results were obtained : — iMoisture A, untreated.- . . 43-54 . . B, treated. 42-70 Bread solids . . 56-46 . . 57-30 Total proteins in bread . . ICO -00 .. 6-76 . . 100-00 6-86 Total digested proteins of each bread 5-72 . . 6-04 Percentage of total protein digested . . 84-61 . . 88-04 WHEAT, FLOUR, AND BREAD IMPROVERS. 507 As the water used in each case was the same, the difference in bread solids was only such as necessarily follows from the irregularities of baking. B had in fact 0-84 per cent, more solids than A. The total protein in each was practically the same ; but under the conditions of the digestion test 100 parts of A yielded 5-72 parts of digested protein, whereas 100 parts of B similarly yielded 6-04 parts. Out of every 100 parts of protein present in A, 84-61 were digested, while out of every 100 parts of protein present in B, 88-04 parts were digested under the conditions of the experiments. The greater digestibility of B was very noticeable during the progress of the test : inspection showed that the more highly vesiculated and spongy crumb of B broke down into a homogeneous pulp much more rapidly than did that of A. In the next place experiments were made with different quantities of water in the untreated and treated loaves. In practice it is very doubtful whether any such use of improvers, as is being described, results in the successful use of more than an extra two quarts of water per sack. That proportion has accordingly been added to the treated flours. Tests were thus made on all-English and all-Manitoba wheat flours. The following are the quantities used : — A. 560 grams English flour untreated, 7 grams salt, 10 grams yeast, 280 grams water (equal to 56 quarts per sack). B. 560 grams same flour treated, salt and yeast as before, 290 grams water (equal to 58 quarts per sack). C. 560 grams Manitoba flour untreated, salt and yeast as before, 280 grams water. D. 560 grams same flour treated, salt and yeast as before, 290 grams water. Particulars are set out of the results of various determinations made, and also of digestion tests like those ca^rried out on the previous flour. English. Manitoba. Weight of dough when scaled, grams Weight of loaves from oven, grams Weight of loaves, next day, grams Greatest height of loaves, centi- metres Moisture by analysis . . Bread solids by analysis. ..... Moisture in B and D, second day, from difference in weight of loaves . . Bread solids from ditto Total proteins in bread Total digested proteins of each bread Percentage of total protein digested A. B. C. D. itreated. Treated. Untreated. Treated. 840 , . 850 00 . . 852 787 . . 790 . . 788 . . 792 763 . . 768 . . 761 . . 765 12-9 . . 15-0 . . 16-8 . . 18-2 43-36 . . 43-40 . . 42-62 . . 42-54 56-64 . . 56-60 . . 57-38 . . 57-46 43-36 . . 43-73 . . 42-62 . . 42-92 56-64 . . 56-27 . . 57-38 . . 57-08 6-82 6-77 8-25 8-20 6-20 6-14 7-06 7-50 90-90 . . 90-69 . . 85-57 . . 91-46 As the result of analytic determinations, the bread solids of the members of each pair of loaves was found to be practically the same. It was there- fore thought to be the fairest comparison to take the analytic data for the first loaf of each pair and then, as each loaf was made from the same weight of flour, to calculate the solids of the second loaves from the difference in 508 THE TECHNOLOGY OF BREAD-MAKING. weight of the two loaves of each pair. These are the figures given as being from difference in weight of loaves.” Evidently they must take cognis- ance of the whole increased weight of bread obtained. In the case of the English flour breads, the loss in weight of solids due to increased yield is 56*64 — 56*27 =0*37 per cent. With the Manitoban flour breads the corresponding loss in weight is 57*38 — 57*08 = 0*30 per cent. The loss in weight of proteins for the two flours is respectively : English, 6*82 — 6*77 = 0*05 per cent., and Manitoban, 8*25 — 8*20 = 0*05 per cent. It is submitted that these differences are so small as to be practically inappreciable. On being subjected to digestion tests, the protein of the English loaves was digested more completely than in the preceding test, and resulted in a slight advantage in favour of the untreated loaf, the difference being 6*20 — 6*14 = 0*06 per cent. With the harder Manitoban wheat flour, digestion pro- ceeded with considerably more rapidity and completeness in the treated and more bulky loaf, the figures being 7*50 — 7*06 =0*44 per cent, in fav- our of the treated loaf. Looking at the whole series of the three sets of tests, there is a decided advantage in protein digestibility in the case of the treated flours. This bears out the previously expressed opinion that a bold, well-risen loaf is more digestible than a small and clammy one from the same flour.” Certainly, these results cannot be said to afford any support to the view that there is a diminution in nutritive value, and “ that the con- sumer in this respect loses by the treatment.” A further question is whether, even if obtainable, any advantage from an increase of yield can long be withheld from the consumer. No doubt for a time any miller or baker who discovers a method of obtaining such increase will benefit thereby ; but almost immediately, he utilises his diminished cost of production by offering his goods at a lower rate than his competitors in order to increase his trade. In a surprisingly short time the advantage is transferred to the community in the shape of a lower price, or increased value in other directions. There are certain towns in which the general taste is in favour of varieties of bread which contain an unusually high percentage of water, but this compensates itself by a lower price for the bread. If the price is worked out on the basis of charge per pound of dried solids it will be found that the consumers of a bread with high water content pay on the average no more than do those who prefer a drier type of bread from flour of the same price. An example of this is that of tlie bread of London and Manchester respectively ; the former is a crusty bread of low water content, while the latter is a tin loaf with a higher percentage of moisture. At the moment of wTiting the Board of Trade Returns give as the price of bread : London, 5Jc?., Manchester, ^d. per quartern loaf. The same laws would naturally operate with any extended improvement in the weaker wheats, It is common ground that some additions effect very marked improve- ments in certain ways, and also that other weird preparations and addi- tions are most dangerous. But it scarcely follows that because some are bad all should be condemned. The whole subject points to the advisability of the establishment of a Court of Reference which should exercise a general supervision over the practice of additions to articles of food. The Court should prescribe such regulations as it deemed necessary, and these would be a guide both to manufacturers and vendors of articles of food, and also to those who are responsible for the administration of the Food and Drugs Acts. The Court should hear applications for permission to employ any process which involved the addition of foreign substances to articles of food, together with arguments and evidence in favour of and against such permission being granted. The Court would then unconditionally refuse or accede to such application, or might grant the desired permission subject WHEAT, FLOUR, AND BREAD IMPROVERS. 509 to conditions. In the last case one of the conditions might be that the nature and objects of the addition should be declared by the vendor. A declaration made under these circumstances would imply that the proposed treatment was not in any way injurious to health. Either on its own initia- tive, or on the representations of parties interested, the Court should be empowered, on proper terms, to review its own decisions, and either increase in stringency, or relax, its regulations as necessity arose. 631. Bread Improvers. — The possibilities of treatment by the baker a^re much greater than those of the miller inasmuch as he can make use of liquids of any description as well as solids. In the manufacture of bread, the addition of certain other substances than flour and water is a recognised and integral part of the manufacture. When brewer’s yeast was the only type used, some yeast stimulant was absolutely necessary for reasons already explained (paragraphs 376-9). Potatoes were found exceedingly useful and convenient for the purpose, and accordingly the potato ferment was at one time a regular part of the process of bread-making. With the use of dis- tiller’s yeast, the necessity of some stimulant for the yeast no longer existed, and accordingly potatoes have largely gone out of use. But there are other functions in bread-making fulfilled by the potato, and these continue to require attention. Substances added for the purpose of effecting improve- ments in bread may be grouped into the following classes : — Milk. — Whole or separated ; improves flavour, appearance and nutritive value. Butter. — This and other fats improve flavour and shorten crust, thus preventing toughness. Moistness-retaininj bodies. — In their pure state, some flours, and par- ticularly those which are the most nourishing as a result of their high per- centage of proteins, produce a bread which readily becomes somewhat dry and harsh. To remedy this, an increase in the quantity of gelatinised starch and dextrin removes harshness and makes the bread remain moist and taste moist much longer. Potatoes. — The ordinary boiled potato has the effect just mentioned. As a substitute, it has been proposed to dry potatoes and grind them into a meal or flour. Such a preparation, however, only adds starch in the ungelatinised form, and cannot increase the moistness as a consequence. Whatever soluble constituents the potato contains are thus introduced into the bread. Re- cently, preparations have been placed on the market which consist of thor- oughly cooked potatoes, dried and reduced to a fine powder. These are capable of acting as a direct substitute for the boiled potato, introducing the same substances and avoiding the mess and dirt which almost of necessity accompany the cooking of potatoes in a bakehouse. Gelatinised Starches. — Among members of this group, the use of scalded flour is 25re-eminent. This adds gelatinised starch, which may be used in a ferment, or if wished may be added to the dough. Scalded rice and maize also produce the same effects. The employment of all or any of these has the advantage of greater cleanliness in manipulation than occurs with potatoes. All are sources of gelatinised starch. Certain grains and other starchy bodies are now gelatinised, dried off and sold in the form of thin flakes. These may be used as ready -gelatinised forms of starch which require no cooking. Dextrinous bodies. — From its well-known gummy properties, dextrin serves to keep bread moist. Its principal sources in bread are, starch which has been converted into dextrin by enzymes, malt extract, and so- called confectioners’ glucose, which is really almost entirely composed of dextrin and maltose (see chapter XXXIII.). Sweetening bodies. — Sweetness may be conferred by the addition of 510 THE TECHNOLOGY OF BREAD-MAKING. pure sugar or by the use of malt extract or “ glucose/’ both of which contain maltose in large quantities. When gelatinised starch is acted on by dias- tase, more or less maltose is formed. Maltose may be thus produced from the starch of the flour itself, or from that added in the gelatinised condition from any other source. In addition to its flavouring properties, sugar serves the yeast as a source of carbon dioxide gas. Diastatic bodies . — Various enzymes serve the purpose of converting starch into dextrin and maltose. Flour itself contains a considerable quantity of diastase. Carefully prepared malt extract is also actively diastatic, while certain special forms contain diastase in a very concen- trated degree. Malt flour, particularly that of air-dried malt, is also rich in diastatic power. All these substances are used for bread-making purposes In addition to the starch converting diastase, these bodies may contain more or less of proteolytic enzymes by which the gluten of flour is affected. The charges thus produced may be beneficial or otherwise according to the nature and quality of the gluten. Mineral bodies . — First among these is common salt, which in addition to its flavouring properties acts as a binding or strengthening agent on the dough. Certain other mineral bodies have beneficial effects on bread. One of these is calcium chloride, which in small quantities serves as a strengthening agent, and also may be useful as a source of lime for nutritive jmrposes. In its general properties calcium chloride falls into somewhat the same category as salt. Magnesium sulphate is at times employed, more especially it is said in some of the Midland counties. For reasons already given, the addition of phosphates and phosphoric acid serves to effect some improvements in bread. Yeast nourishing bodies . — Several of the substances already mentioned are of service as direct or indirect yeast foods ; among these are sugars and the bodies from which derived, the diastases which produce sugar, and some mineral salts. In addition to these some bodies rich in organic nitrogenous constituents are of value as food and stimulants for yeast. 632. Malt Extract. — This being one of the substances most largely used for the improvement of bread, its preparation and properties require a somewhat extended description. Malt extract is prepared by evaporating at a low temperature in vacuo the filtered wort from mashed malt until the resultant liquid is of the consistency of a thick syrup. In order to investigate the composition of malt extract under different conditions, the folloving experiments were made : — A high quality sample of pale malt w'as finely ground ; and of this 500 grams w ere taken, mixed whth 2,000 c.c. of w^ater, and mashed for 2 hours, at a temperature of 60° C., in a w'ater- jacketed pan. The resultant wort was then filtered bright, and the “ grains ” w^ashed, dried and w'eighed, their w^eight being 113 grams, showing that over 75 per cent, of the ma’t had gone into solution. This w'ort w^as called Preparation I., Unevaporated. A portion was reserved for analysis, and the remainder evaporated in vacuo, the operation being pushed as far as possible : this constituted Preparation I., Evaporated. Another 500 grams of the malt w'ere then taken, mixed with 2,000 c.c. cold water, continually stirred during 3 hours, and then allow ed to stand overnight. The clear liquid was poured off in the morning, the residual malt drained moderately dry. The liquid was filtered bright, and consti- tuted Preparation II., Unevaporated. A part of this was evaporated in precisely the same manner as with No. I., and is termed Preparation II., Evaporated. The residual malt from No. II. was next taken, mashed with 2000 c.c. WHEAT, FLOUR, AND BREAD IMPROVERS. 511 more water for 6 hours, at 60° C., and then raised to 100° C., and filtered bright. This constituted Preparation III., Unevaporated. A portion vv'as evaporated in vacuo as before, and this formed Preparation III., Evapor- ated. Each of these was then subjected to analysis, determinations being made as given in the table on page 512, in which are also included similar analyses of commercial samples of guaranteed pure malt extract. ^^arious determinations, as given below, were made on the Unevaporated Preparations. Xo. I. No. II. No. III. Specific gravity at 150° C 1,057-5 1,020-7 1,050-0 Dry Solids, grams per ICO c.c. calculated from gravity . . . . . . . . . . 14-93 5-37 13-CO Dry Solids, grams per ICO c.c. by evaporation and weighing . . . . . . . . 14-06 4-93 12-78 Dry Solids, weight in percentages . . . . 13-30 4-83 12-17 The method of analysis employed is that described in Chapter XXIX., and is subject to the limitations of accuracy there explained. It should be mentioned that all the figures, both on the liquids and the extracts, are the results of direct determinations ; the percentage composition of “ Dried Solids being calculated from those obtained in the liquid or extract with water present. The dextrin was precipitated by alcohol and corrected for solubility and amount of precipitated protein : it no doubt contains not only pure dextrin, but also the other gum-like substances frequently returned as “ indeterminate bodies.” The No. I., or whole extract, contained sucrose in the wort, but this disappeared during concentration. The g'ucoses also show a diminution, while dextrin increases. The dextrin precipitate in the evaporated extract was much darker, and evidently contained a considerable proportion of products of caramelisation. The cold water extracts. No. II., are very interesting. The proteins and phosphates are very high : so also is the sucrose, which, however, diminishes on concentration. The quantity of maltose is very small, while the glucoses represent about half the total weight of the solids present. The sugars here again diminish during concentration, while dextrin increases, no doubt for the same reason as in No. I. In No. III., as might be expected, sucrose is absent, any traces in the original solution being doubtless destroyed during the prolonged mashing. Glucose (dextrose), and laevulose are present in very small quantity, the sugar being almost entirely maltose. As might be expected, the dextrin is high, and the act of concentration has produced practically no alteration in the pro- portions of the constituents present, the lengthened period of mashing and subsequent boiling having reduced all bodies present to a stable condition. The above three types of extract are sometimes called — No. I Whole extract, being the entire extract of the malt. No. II. Cold water extract, from the fact of its containing the cold water soluble constituents only. No. III. Spent extract, being prepared from the comparatively spent grains after extraction with cold water. This is also sometimes called a “ split ” extract, since the products of the malt are split into two separate lots in its production. All three of these are more or less represented in commercial extracts, the first being the older and purely normal type of the whole malt. With the demand for extracts of high diastatic power, No. II. type came into the market. The manufacture of No. II. made the preparation of No. III. a 512 THE TECHNOLOGY OF BREAD-MAKING. Analyses of Malt Extract Preparations. Constituents. Water . . Mineral Matter (Phosphates) Proteins Dextrin . . Sucrose . . Maltose . . Glucose and Lsevulose Cuprous Oxide, CU 2 O, from 100 grams Reducing Sugars, calculated entirely Maltose Water . . Mineral Matter (Phosphates) Proteins Dextrin . . Sucrose . . Maltose . . Glucose and Lsevulose Cuprous Oxide, CU 2 O, from 100 grams Reducing Sugars, calculated entirely Glucose and Lsevulose M'ater . . Mineral Matter (Phosphates) Proteins Dextrin Sucrose . . Maltose Glucose and Lsevulose Cuprous Oxide, CU 2 O, from 100 grams Reducing Sugars, calculated as Maltose Water . . Mineral Matter (Phosphates) Proteins Dextrin . . Sucrose . . Maltose . . Glucose and Lsevulose (’uprous Oxide, CU 2 O, from 100 grams Reducing Sugars, calculated as Maltose No. I., Unevaporated.' No. II., Evaporated. Whole i j Liquid. | Dried Solids. Whole Extract. Dried Solids. 1 86-70 14-70 0-24 1-77 1-70 1-99 ' 0-86 6-44 5-27 6-18 1-32 9-95 10-82 12-68 0-43 3-23 Absent Absent , 9-04 68-03 60-97 71-48 ' 1-41 10-58 6-54 7-67 1 100-00 1 100-00 100-00 I 100-00 13-99 105-2 87-50 103-70 . 11-30 84-93 70-67 82-85 1 No. II. 5 Unevaforated No. II., Evaporated. 95-17 , 22-90 0-32 6-52 4-80 6-23 0-80 16-56 12-71 16-49 0-60 12-36 13-66 17-72 0-45 9-31 4-79 6-21 0-21 4-20 1 2-69 3-48 2-45 51-05 * 38-45 L 49-87 100-00 100-00 100-00 i 100-00 5-11 106-43 79-49 103-10 2-57 53-66 40-08 51-99 No. III. Unevaporated No. III., Evaporated. 87-83 — 11-20 0-17 1-40 Ml 1-24 0-44 3-61 3-37 3-79 2-44 20-03 17-40 19-60 Absent Al sent Absent Absent 8-82 72-45 66-06 74-40 0-30 2-51 0-86 0-97 100-00 100-00 100-00 100-00 11-52 94-67 83-5 94-03 9-31 1 76-48 67-44 75-94 First Commercial Extract. Second Commercial Extract. Whole Extract. Dried Solids. Whole Extract. ; Dried Solids. 22-23 27-64 1 1-10 1-42 1-40 1-93 3-01 3-88 4-74 i 6-55 12-90 16-59 5-80 8-02 3-59 4-61 1-92 2-66 54-84 70-51 53-65 74-14 2-33 2-99 4-85 6-70 100-00 100-00 100-00 100-00 72-5 93-22 80-0 110-5 58-55 75-28 64-61 89-29 WHEAT, FLOUR, AND BREAD IMPROVERS. 513 necessity in order to utilise the very large proportion of residual matter from making the cold water extract. In diastatic power. No. I., if properly prepared and carefully concen- trated, should be of fair quality. No. II. will be of very high diastatic value, while No. III. will be devoid of any diastatic power whatever. Modern manufacturing processes are a combination of the various methods described, mashing being made at various temperatures, or at a lower than normal temperature in order to retain diastase ; while a good deal of the purely saccharine extract is sacrificed, or obtained in a further extraction, when it may or may not be mixed in with the first or more dias- tatic extract. The samples of commercial extract call for but little remark ; in the first, the dextrin is fairly high, and so also is the maltose ; sucrose, dextrose, and laevulose being present in small quantity. At the same time, the sample is well concentrated, but 22-23 per cent, of water being present. With any less moisture the extract would be too stiff to pour out of tins or drums when cold. The second commercial sample affords evidence of having been worked at a higher temperature, although the degree of concentration is less. Both these extracts show all signs of being nothing beyond pure, normal extracts of malt. In breadmaking, the addition of malt extract, in the first place, increases, to the extent to which it is used, the quantities present of the various in- gredients of the extract, among which are sugars which impart sweetness ; dextrin, by which the bread is caused to remain moister ; and phosphates, which add to the bone-forming materials, and also act as a yeast stimulant. There is in addition the specific effect on the constituents of the flour caused by the diastase present in the extract. 633. Malt Extract, Commercial Manufacture, British. — The following is a description of the method of malt extract manufacture as carried out by the British DiaMalt Company at their works at Sawbridgeworth, by whom the authors were afforded full opportunities of experimental investi- gation of their various processes on the spot. The factory is conveniently situated near the principal barley growing districts of England, and comprises in the first place large makings, both on the floor, and the pneumatic systems. Explanations of both these have been already given in paragraph 39L The Company also imports large quantities of Hungarian barley and malt. The malt is first screened, and then ground in a Seck-mill, after which it finds its way into the mash-tun, where only malt and water are used. (The manufacturers make a great point of their claim that their extract is the product of pure malt only, and that no malt substitute finds its way into their factory.) An examination of the preparation made for bakers and sold to them under the name of Diamalt shows it to be prepared from a pale diastatic malt, which has evidently been mashed at a comparatively low temperature in order to conserve the diastase as much as possible. In consequence the colour of the extract is lighter, and the yield less for a given weight of malt than when higher temperatures are employed and the mash- ing pushed further. The diastase and protein contents exist therefore in a more concentrated form in Diamalt than in higher temperature extracts. The British Company is an offshoot of the parent European Company, and manufactures the extract from a general formula employed by that com- pany. They are therefore under an embargo of secrecy, and a demonstra- tion of their whole process was only given in strictest confidence. The authors can only say that the mashing and concentration in vacuo are con- ducted in plant of the most modern and perfect description, and under conditions of the most absolute cleanliness. The principle of the whole- L L '514 THE TECHNOLOGY OF BREAD-MAKING. ■operation is very simple, but at all stages the greatest possible care and attention are required in order to maintain the correct temperatures on Avhich the success or non-success of the manufacture depends. The follow- ing are the results of an analysis of the extract thus obtained : — Gravity of 10 per cent, solution . . 1,029 Opticity of 10 per cent, solution in 2 decimetre tube . . 15-40° Water . . 26-56 Mineral Matter (Phosphates) . . 1-06 Proteins . . 5-88 Dextrin . . 4-65 Sucrose . . . . 2-87 Maltose . . . . 39-53 Glucose and Lsevulose . . 19-45 100-00 Cuprous Oxide, CuaO, from 100 grams . . 87-5 grams, Reducing Sugars calculated entirely as Maltose 70*67 Diastase expressed in degrees Lintner 90*0 In bread-making tests with this extract, the rate of fermentation was accelerated, and the percentage of soluble matter in the bread increased. In consequence there was a decided gain in the moistness and flavour of the bread. In consequence of the presence of proteolytic enzymes, the gluten of the flour was softened during fermentation ; a result which is of special value wLen a preponderance of very hard flour is used. 634. Malt Extract, Commercial Manufacture, American. — With their •comparatively hard flours, American bakers And in malt extract an adjunct used probably even more extensively than in Great Britain. Important information both as to the manufacture and employment of malt extract in America has been furnished to the authors by the Malt-Diastase Com- pany of New York, one of whom recently visited their factory in Brooklyn. The principles of the methods of manufacture, Le., mashing and subsequent evaporation in vacuo, are obviously as already described. The following -p.re analyses of three brands of extracts supplied by this Company. All al’e made from pure malt prepared from barleys grown in Minnesota and North-Avestern Iowa, selected because of their high protein content. The different characters of the various extracts is determined almost entirely by .the selection of malts and appropriate modifications of the mashing process. In estimating diastatic activity for bakers’ purposes, the Company •employs what is known as the unit method, i.e., one part of extract is alloAved to act for 30 minutes upon an excess of 3 per cent, starch solution, at a temperature of 99° F., and the resulting sugar (maltose) determined. If the maltose produced is equal in Aveight to the extract used, the extract is said to have a diastatic poAver of one unit. In other Avords, the weight of sugar produced, divided by that of extract used in the test, gives the number of units of diastatic capacity. It Avill be noticed that this is a starch paste determination as against the soluble starch method of Lintner. The under- mentioned data AA'ere furnished by the manufacturers : — No. 1. Name of brand. — Diax. ,, 2. ,, ,, ,, O.P. Malt Extract. „ 3. ,, „ ,, Standard Malt Extract. 1 2 . 3 . Specific Gravity . . .. .. .. 1-375 1-375 1-373 Diastase expressed in units . . . . 9-35 4*01 3-63 ,, „ ,, degrees Lintner . . 146-31 59 02 51-21 Acid calculated as Lactic .. .. 1-248 1*07 1’08 WHEAT, FLOUR, AND BREAD IMPROVERS. 515 The authors obtained the following results on analysis Gravity of 10 per cent, solution .. 1,030-2 1,030*0 1,029-2 Opticity of 10 per cent, solution in 2 decimetre tube . . 12-266° 13-000° 13-616 Water, including about 2 per cent, of alcohol 30-42 29-73 29-86 Mineral Matter (Phosphates) 1-54 1-58 1-42 Proteins 8-03 6-93 6-19 Dextrin 6-30 4-55 4-70 Sucrose 0-48 0-48 1-44 Maltose 28-26 32-88 38-69 Glucose and Lsevulose 24 97 23-85 17-70 Cuprous Oxide, CU 2 O, from 100 grams 100*00 84-5 100*00 88-0 100*00 830 Reducing Sugars calculated entirely as Maltose 68-25 7107 67-04 Diastase expressed in degrees Lintner 139-0 79-2 72-8 The No. 1 or Diax is a malt extract of exceptionally high diastatic capa- city, and is probably prepared for the use of those who prefer an extract of great converting power. Nos. 2 and 3 are more alike in character, and both possess a high diastatic value for bakers’ extracts. They also contain an active amount of proteolytic enzyme (protease or peptase) and conse- quently produce considerable gluten-softening effects. With hard flours a limited softening is very desirable, but with the weaker varieties this must not be allowed to become excessive, as the doughs are then rendered too soft and sticky. A description has been already given in Chapter XVIII. of the use of malt extract in American bread-making methods. A process, which is largely used in that country, consists in the employment of a gelatin- ised starch, such as corn flakes, allowing the extract to convert the starches into sugar and using the resulting mixture as a medium in which to grow a short ferment of one hour, as one hour simply gives the yeast an oppor- tunity to consume the sugar and is not sufficiently long to permit it to reproduce itself. Ten and twelve minute ferments are also recommended so as to give the yeast an opportunity to become enlivened and the individual cells to become covered with pabulum. The Malt-Diastase Company has devoted considerable attention to the use of malt extract in barms. The object here is to make a smooth batter and by adding the proper quantity of water at 212° F. to strike a mean temperature of 170°, being sufficient to gelatinise the starch and yet not hot enough to coagulate the albumins. This permits the hydrolysis of the starch into maltose, etc., and at the same time leaves the glutenous portion in a position to be acted upon by the protease of the malt. By allowing the mixture to stand for 12 hours or so, the peptonising action seems to be quite considerable ; and as it keeps well, the barm gives the baker very little trouble. Experimentally, the Company state that they have used this barm after standing 5 days, and the results seem to be even better as regards flavour than when used fresh. The following is their recipe for the preparation of such malt extract barm : — Malt Extract Barm. Total ingredients used . — Malt extract, 3 lbs. ; flour, 3 lbs. ; water, 2 gallons. Procedure . — Take flour, 3 lbs. ; malt extract, J pint ; water at 130° F., 516 THE TECHNOLOGY OF BREAD-MAKING. 1 gallon. Place these into a suitable container and make into a smooth batter. Boiling water (212° F.), 1 gallon. Pour this into the batter just made, stirring constantly the while ; the more rapidly the boiling water is added the better. Allow this mixture to cool until the temperature reaches one hundred and forty (140°) F., then add the remainder of the malt extract. The digestion of the starches will be complete in 30 minutes, and the barm is ready for use just as soon as the temperature reaches 86° F. If in a hurry it can be cooled by pouring it over cracked ice through a colander Quick result, however, defeats one of the better features of the barm, namely the generation of the peptones from gluten by the protease of the malt extract. It is recommended therefore that the barm be made one day and used the next. The formula as given is recommended for flavour, also for the production of sugar. The amount of flour in the formula can be in- creased if desired, or the baker may add Sako or flakes to increase the pro- portion of sugar. Each pound of flour will yield | lb. of malt sugar when treated in this manner. If the baker desires to use hops he can substitute a boiling infusion of them for boiling water. This is not precisely a barm in the sense in which that term is used in Great Britain, but rather a mash from which by fermentation either a barm (i.e., a yeast) or a ferment may be prepared. 635. Further Analyses of Malt Extract. — By kind permission of Messrs. Peek Frean & Co., Ltd., biscuit manufacturers, the following particulars of malt extracts are herein given. This firm procured from various sources Physical Characters of Malt Extracts. Reference Letter. Colour. Consistency. Odour. Flavour. A Light 1 Medium Pleasant Clean, sweet. B Medium . . Medium Less pleasant Bitter, sweet, cling- ing. C Light Medium Pleasant Clean, sweet. D Light Medium Pleasant Disagreeable. E Medium . . Stiff and crys- talline Peculiar Recalls low grade honey. F Medium . . Medium Slightly burnt Slightly burnt but clean. G Light Rather thin Pleasant D isagreeable, bitter . H Dark Medium Burnt Very disagreeable. J Very light Tenacious . . Pleasant Pleasant. , K Light Rather thin Pleasant Raw, but clean. L Dark Very thin . . Pleasant Rather like E. M Medium . . Medium Very slightly burnt Burnt, bitter, dis- agreeable. N Very light Tenacious, granular Pleasant Pleasant. 0 Medium . . Medium Peculiar , Peculiar, unpleas- ant. P Dark Rather thin Very slight. . Unpleasant. R Medium . . Medium Pleasant Pleasant. S Very light Very tenacious Pleasant Sweet, very pleas- ant. T Light Exceedingly tenacious Pleasant 1 Sweet. WHEAT, FLOUR, AND BREAD IMPROVERS. 517 altogether eighteen samples of extract, which samples are practically repre- sentative of all those offered on the market for bakers" and confectioners" use. They were analysed, otherwise tested, and systematically reported on by one of the authors. In the examination the objects kept in view were the following : — (1) To ascertain the purity or otherwise of the samples. (2) To determine their chemical composition in so far as it bears on their quality, and mode of extraction. (3) To advise as to their comparative suitability for use as an adjunct in goods manufactured from flour. The samples were examined as to their physical characteristics, observa- tions being made as to their colour, consistency, odour, and flavour. The results of this examination are embodied in the table given on the preced- ing page. Remarks : — E. Odour and flavour recall low grade honey, gritty on the palate through presence of crystallised sugar, colour a curious drab, abnormal as Sj malt extract. L. Character closely resembles that of E, but thinner, both devoid of ■characteristic malt flavour. N. Slightly crystallised. O. Odour reminded one of compressed yeast. S. Flavour malty, very free from bitterness. T. Flavour sweet but devoid of malt character, recalls brewers" invert ■sugar (see page 86). In the course of analysis the following determinations were made — water, mineral matter, proteins, dextrin, sucrose, maltose, and glucose. The flrst three estimations are quite plain. The remaining constituents may be grouped together as carbohydrates. Their separation into dextrin, sucrose (cane sugar), maltose and glucose was made by methods described in the latter part of this work. They give only approximate, but still fairly accurate, results. The “ reducing sugars as maltose "" were obtained by calculating the whole of the precipitated copper oxide as being due to mal- tose. As throughout the whole series the same processes were employed, the Tesults are comparable with each other. The previously given results of analysis of extracts prepared in the author"s laboratory, paragraph 632, should be studied and compared with those following on page 518. Considerable importance attaches to the diastatic capacity of malt •extracts, or the power the extract possesses of activity on starch, converting it into dextrin and maltose. In order to measure the capacity for effect- ing this conversion, the effect produced by the extracts on flour was deter- mined, that used being a weak patent flour and the same for the whole series. The tests were made in the following manner — 100 parts by weight of flour were taken together with 2 parts of malt extract, and 400 parts of water. These were placed in a tightly corked flask, thoroughly shaken together, and then maintained for 4 hours at a constant temperature of 140° F., the flasks being frequently vigorously shaken. At the end of the time the contents were filtered, and on the clear filtrate determinations were made of the total soluble matter, and of the maltose produced. As flour a,lways contains some reducing sugar and other soluble matter, these were determined by an experiment on the same quantities of flour and water only, allowed to stand in the cold for 4 hours and then estimated precisely like the extracts. Flour itself also contains diastase, and to determine the effect produced by this (flour diastase) an experiment was made on the .■same quantities of flour and water only, maintained at 140° F. for 4 hours. 518 THE TECHNOLOGY OF BREAD-MAKING. Analyses of Malt Extracts. Reference Letter — a. B. 1 i c. i 1 D. E. F. Water 27-70 29-90 27-90 26-30 25-90 24-80 Mineral Matter 1-25 1-65 1-70 1-60 1-80 1-40 Proteins 3-81 4-87 6-29 5-40 6-02 3-81 Dextrin 8-70 4-60 4-80 7-65 2-70 10-95 Sucrose 3-35 3-83 1-91 4-07 5-74 6-46 Maltose 42-87 22-63 29-29 47-01 40-53 50-02 Glucose 12-32 32-52 28-11 7-97 17.31 2-56 100-00 100-00 100-00 100-00 100-00 100-00 Reducing Sugars Maltose as 62-59 74-71 74-31 59-76 68-25 54-11 Reference Letter — G. H. j. K. L. M. Water 29-80 29-20 25-60 28-50 30-60 28-80 IMineral Matter 1-85 1-90 1-15 1-45 1-85 1-75 Proteins 9-30 9-83 6-77 6-29 6-29 9-12 ' Dextrin 3-30 3-00 8-35 3-75 3-50 2-50 Sucrose ' Nil Nil 6-46 1-91 7-42 1-91 Maltose 23-56 34-48 42-23 35-72’ 31-30 28-71 : Glucose 32-19 21-59 9-44 22-38 19-04 27-21 1 100-00 100-00 100-00 100-00 100-00 100-00 ; Reducing Sugars Maltose as 75-11 69-05 57-34 71-88 6D79 72-29 Reference Letter — ' X. 0. p. R. s. T. ^ Water 24-40 27-30 28-90 25-30 22-20 18-30 Mineral Matter 1-50 0-85 1-55 1-55 1-45 1-35 Proteins 7-17 7-97 6-38 7-70 4-96 7-62 Dextrin 1-30 3-30 3-20 4-45 8-85 6-35 Sucrose 0-72 1-19 Nil Nil 4-31 8-14 Maltose 47-94 33-92 37-34 33-50 53-65 46-95 : Glucose 16-97 25-47 22-63 27-50 4-58 11-29 100-00 100-00 100-00 100-00 100-00 100 00 : Reducing Sugars Maltose as ■■ 1 75-11 74-71 73-50 1 77-53 1 60-98 65-02 : WHEAT, FLOUR, AND BREAD IMPROVERS. 519' In addition, the malt extract also contains maltose and other soluble matters. In the following table, there is given on Line 1, soluble matter normally present in the flour. Line 2, additional soluble matter resulting from the diastatic influence of the flour upon itself during the 4 hours at 140° F., being self- or auto- digestion. Line 3, soluble matter contained in the malt extract. Line 4, additional soluble matter resulting from the diastatic action of the malt extract upon the flour. Soluble Matters resulting from Action of Malt Extract on Flour. Reference Letter — . A. B. c. i n. E. ; F. Normally present in Flour. . 5-52 5-52 5-52 5-52 1 5-52 5-52 Flour, Auto-digestion 31-88 31-88 1 31-88 31-88 ^ 31-88 31-88 In Malt Extract 1-44 1-40 j 1-44 1-47 i 1-48 1-50 Malt Extract digestion 5-28 11-04 1 1 16-36 10-29 ! 12-12 8-98 i Total 44-12 49-84 55-20 49-16 51-00 47-88 Reference Letter — . G. H. J. Iv. L. M. Normally present in Flour 5-52 5-52 5-52 5-52 5-52 5-52 ! Flour, Auto-digestion 31-88 31-88 31-88 31-88 I 31-88 31-88 In Malt Extract 140 1-41 1-48 1-43 1-38 1-42 Malt Extract digestion 18-12 17-67 9-36 17-61 16-74 17-10 Total 56-92 56-48 48-24 56-44 55-52 55-92 Reference Letter — . N. 0. R. R. i T. Normally present in Flour 5-52 5-52 ! 5-52 5-52 5.52 5-52 Flour, Auto-digestion 31-88 31-88 31-88 31-88 1 31-88 31-88 In Malt Extract 1-51 1-45 1-42 1-49 ! 1-56 1-63 Malt Extract digestion 13 57 1595 14-06 16-55 8-28 10 *77 Total 1 52 48 1 54-80 i 52-88 1 55-44 1 1 47-24 1 49-80 1 The table on page 520 gives the result of determinations of reducing sugars calculated as maltose. The arrangement is the same as in the preceding table. The results in both tables are given in percentages of the flour used.. The reducing sugars are throughout assumed to consist entirely of maltose. The amounts of “ soluble matter and “ reducing sugar run closely parallel throughout the whole of the two series. It will be observed that flour itself possesses considerable diastatic power, having converted over one-fifth of its weight into sugar under the conditions of the test. The dias- tatic action of the extracts varies from 2*47 per cent, of flour into maltose with A to 16*01 per cent, with K. There is considerable difficulty in detecting with certainty adulterations of malt extracts, firstly because of the great variations in composition. 520 THE TECHNOLOGY OF BREAD-MAKING. Reducing Sugars resulting from Action of Malt Extract on Flour. ; Reference Letter — . A, B. c. D. E. F. i Normally present in Flour 1-97 1-97 1-97 1-97 1-97 1-97 Flour, Auto-digestion 20-80 20-80 20-80 20-80 20-80 20-80 j In Malt Extract 1-25 1-49 1-48 1-19 1-36 1-08 I Malt Extract digestion 2-47 ’8-85 13-71 7-38 10-60 6-84 Total 26-49 33-11 37-96 31-34 34-73 30-69 Reference Letter — . G. H. j. K. L. M. Normally present in Flour. . 1-97 1-97 1-97 1-97 1-97 1-97 Flour, Auto-digestion 20-80 20-80 20-80 20-80 20-80 20-80 ’ In Malt Extract 1-50 1-38 1-14 143 1-23 1-44 Malt Extract digestion 15-94 15-42 7-91 16-01 15-57 15-84 Total 40-21 39-57 31-82 40-21 39-57 40-05 Reference Letter — . N. 0. p. R. s. T. ' Normally present in Flour. . 1-97 1-97 1-97 1-97 1-97 1-97 Flour, Auto-digestion 20-80 20-80 20-80 20-80 20-80 20-80 In Malt Extract 1-50 1-49 1-47 1-55 1 22 1-30 Malt Extract digestion 11-11 14-67 1227 14-29 6-95 9-65 Total 35-38 38-93 36-51 38 61 30-94 33-72 resulting from different modes of treatment of the same malt (see analyses, paragraph 632), and secondly because malts themselves differ very consider- ably in composition, according to whether “ green "" or air-dried, amber, or high kiln-dried. Further, the usual adulterants consist of the same constitu- ■ents obtained from other and cheaper sources. The following is an attempt at a classification of the foregoing extracts : — Whole Extracts . — The following have a high proportion of maltose and low glucose, and are similar in general character to the whole extract of a good pale malt : — D. Flavour, low ; diastase, medium. F. Over-heated ; diastase, low. S. Flavour, best of all ; diastase, low. Cold Water or Partial Extracts . — These are characterised by having a low proportion of maltose and high one of glucose. The diastase runs from medium to high. They are also probably prepared in some cases from green or air-dried malts. Extracts of this class lay themselves open to sophisti- cation since a small quantity of the air-dried malt yields an extract of very high diastatic value ; and admixture of glucose, dextrinised starch, or brewers’ invert sugar, either during or after manufacture, can easily be made, Buch mixtures would resemble the pure extracts of this class very closely. B. Flavour, low ; diastase, low ; glucose, high. C. „ good ,, fair. 521 WHEAT, FLOUR, AND BREAD IMPROVERS. G. Flavour, low diastase, high. H. ? ? very low ,, high. K. 5 ? fair ,, high. M. ?? very low ,, high. 0. ? ? low ,, good. P. j ? low ,, moderate. R. 95 good good. Unclassified Extracts . — These do not fall definitely into either of the fore- going two classes. A. On the whole similar to ‘‘ whole extract,'' but diastase practically absent. Flavour, good. Probably over-heated in earlier stages of manu- facture. E. Abnormal. Dextrin, very low. Flavour, peculiar. Diastase, fair. (Adulteration with brewers' invert sugar ?) J. Probably a whole extract, mashed at a low temperature, intermediate between first and second type extracts. Probably somewhat over-heated in earlier stages of manufacture, as diastase is low. Still, a fair quality extract. L. Abnormal. In flavour resembles E, same suggestion of brewers' invert sugar. The diastase is high. Dextrin is low. N. Abnormal. Flavour recalls brewers' invert sugar. Diastase, fair. Dextrin is low. T. Very low percentage of water, entire absence of burnt flavour, and also, that of malt deficient. Cane sugar high. Query, cane sugar adultera- tion ? Careful examination of the whole of these extracts leads to special notice of sample S as a whole extract, and sample K as a type of the highly diastatic extracts. 636. Commercial Bread Improvers. — These consist principally of the substances described in a previous paragraph (631), either alone, or mixed in various proportions. One of those most extensively advertised was recently analysed by the authors with the following results : — Mineral Matter .. .. .. .. 0*20 per cent. Moisture Insoluble Proteins Soluble Proteins Other Soluble Matter Starch, etc. 7-55 3-60 1*89 37-36 49-40 Opticity of 20 per cent, solution Ditto after inversion 100-00 . . + 8 - 866 ° .. - 1 - 200 ° Amount of change . . . . . . . . 10-066° Cane sugar calculated from opticity determinations, 27 -80 per cent. The composition agrees very closely with that of a mixture of three parts of malt flour to one part of cane sugar. 637. Restrictions on Use. — It must not be assumed because the authors have enumerated these various substances that are or have been used with the object of effecting improvements in flour or bread, that in their opinion all such substances are well adapted for that purpose or can be recom- mended for such. Obviously neither all nor many of them can be used together, since they aim at remedying opposite deficiencies. Thus some are corrections of the weak flours, while others deal with defects associated with over- strength. In the language of pharmacy, these are incompatibles. 522 THE TECHNOLOGY OF BREAD-MAKING. If that which is the A^Tong specific be applied, the remedy may be worse than the disease. The following are the legal restrictions on the range of materials that may be used in the manufacture of bread. The quotation is from the Bread Acts, 1822 and 1836 : — “ Bread made of the articles herein mentioned may he sold. II. And be it [further] enacted. That it shall and may be lawful for the Several Bakers or Sellers of Bread within [out of] the City of London and the Liberties thereof, within [and beyond] the Weekly Bills of Mortality, and within [beyond] Ten Miles of the Royal Ex- change, to make and sell, or offer for Sale, in his, her, or their Shops, or to deliver to his, her, or their Customer or Customers, Bread made of Flour, or Meal of Wheat, Barley, Rye, Oats, Buck Wheat, Indian Corn, Peas, Beans, Rice, or Potatoes, or any of them, and Avith any common Salt, pure Water, Eggs, Milk, Barm, Leaven, Potatoe, or other Yeast, and mixed in such Proportions as they shall think fit, and AA’ith no other Ingredients or Matter AA'hatsoever, subject to the Regulations herein-after contained.” The above section strictly limits the materials from aaLIcIi bread may be made. The meal or flour of most of the cereal bodies is permitted, and also of peas, beans, and potatoes. So, too, are eggs and milk, and any form of leaven or yeast. The latter terms AA^ould probably also include any substance used as a part of a “ ferment.” Cane sugar, glucose, malt, malt extract, and hops, AA'ould most likely fall AAuthin the category as constituents of yeast, using that AA'ord in the AAuder sense in AALich it AA^as understood at the passing of the Act. Since 1822, there have been developments and improvements in the substances suitable for bread-making purposes. Arnong these may be mentioned banana-meal, malt extract used other than as a yeast constituent, butter or other fats, cream of tartar, carbonate of soda, and other aerating bodies. As the Act stands, the use of any of these is prohibited. The laAV in this particular is a dead letter, but still it remains on the Statute Book, should any one see fit to resurrect it. The bearing of The Sale of Food and Drugs Acts has also to be con- sidered. Their general effect is that the mixing of any ingredient AAdth an article of food, so as to render it injurious to health, is prohibited. Further, no person may sell to the prejudice of the purchaser any article of food AA'hich is not of the nature, substance and quality of the article demanded. It may be argued that flour or bread having any addition made thereto is not of the nature, substance and quality of the article demanded. If so, the further question arises, if the addition is in every AA^ay an improvement, and in no AA^ay an injury, has an offence been committed ? In deciding a case in AALich this point arose, the learned judge said : “ The AAmrds ‘ to the prejudice of the purchaser ’ are necessary, because if they had not been inserted, a person might have received a superior article to that AAfliich he demanded and paid for, and yet an offence AA'ould have been committed. The AA'ords are intended to sIioaa' that the offence is not simply giving a dif- ferent thing, but giving an inferior thing to that demanded and paid for.” Presumably, therefore, the addition of an “ improver,” AALich does in fact improAm the article, does not come AAuthin the purvieAV of the Act. It AAill be noticed that most of the suggested modes of improvement consist either of modifications of the manufacturing processes or the ad- dition of substances AALich are themselves naturally present in flour. Fur- ther, in those defective flours to Avhich it is proposed that the additions should be made, there is less of the substances than is naturally present in flours of the best type, so far as the particular defect proposed to be remedied is concerned. WHEAT, FLOUR, AND BREAD IMPROVERS 523 638. General Opinion of Chemical Authorities. — Public analysts, on A^'hom the responsibility for advising action on these matters rests, are somewhat sharply divided in opinion on this point. This is well illus- trated by their attitude toward certain operations in the manufacture of vinegar. Among the substances naturally present in vinegar there are some which very much impair its keeping qualities. In consequence, vinegar brewers have devised methods of removing these objectionable bodies. In discussing this treatment of vinegar, the following opinions were expressed by high chemical authorities. A speaker on one side wished to protest against the removal of these bodies, and “ thought that the manufacturer had absolutely no right to effect such a removal. The removal was prejudicial to the purchaser. . . . Here again he was of opinion that the long-recognised and legitimate modes of manufacture should be adhered to, and the introduction of chemical meddling with food materials resisted. It should not be left to the discretion of the manu- facturer of articles of food to say which constituents were valuable and essential and which were not, and in no case should such removal be effected without due notice to the purchaser."' The following speaker “ entirely disagreed with the preceding one, tliat a vinegar manufacturer was not at liberty to remove things prejudicial to vinegar. It was, in his opinion, the manufacturer’s business to make good vinegar, and so long as he sold it for \vhat it was, he was at perfect liberty to remove any objectionable constituents which impaired its qualities.” The same line of argument would justify the removal of undesirable colour- ing matter from flour. The speaker would probably agree that it is the business of the miller and baker respectively to make the best possible flour and bread, though it does not quite follow that he would approve of the addition of commendable bodies as well as the removal of those w'hich are objectionable. Critics as a class have not been famed for their constructive capacity, and it is only fair to remember that the manufacture of vinegar, of flour and of bread, in common with that of most other commodities, has been slowly progressive in its developments, as the result of the application of improvements devised by the manufacturers themselves. It would there- fore seem scarcely logical to step in at any moment and say these articles of food shall consist of bodies made by the methods so far devised and gradually adopted by the makers ; but they, the manufacturers, shall not be permitted to employ any further improvements they may invent or discover. The public may safely be trusted to discriminate between those modifications wliich in their opinion are improvements and those wdiich are not. It follow^s that in this direction liberty of action should be allow^ed to manufacturers, subject to nothing being permitted wliich is to the prejudice of the purchaser, or is injurious to health. If any strengthening of the present law^ be deemed advisable, it is again suggested that it should be in the direction of the establishment of a Court of Reference on the lines indicated on page 508. 639. Notice of Mixture. — By Section 8 of the Sale of Food and Drugs Act, 1875, it is specially enacted that, subject to certain conditions, it shall not be an offence to sell an article of food mixed with any matter or ingredi- ent not injurious to health, if at the time of delivering such article the vendor “ shall supply to the person receiving the same a notice, by a label distinctly and legibly wultten or printed on or with the article to the effect that the same is mixed.” It is often urged that if certain additions to flour or bread are in fact improvements, the vendor w'ould fully comply with the law' and satisfy general requirements, if the article w'ere sold with a declaration 524 THE TECHNOLOGY OF BREAD-MAKING. of such addition in the form required by the section. just quoted from the Act. To this, the vendor usually raises the objection that any such declar- ation might be used to his injury by rival traders. Further, that the pro- ceedings of some officials responsible for the administration of these Acts renders such a course impossible. It must be admitted that there is some force in the latter of these contentions. While this chapter was being written, the following was brought to the notice of the authors. The Chief Foods Inspector reported to the Sanitary Committee of one of the largest boroughs in England that calcium phosphate was being added to flour and bread by millers and bakers. He then comments as follows : — “ I need not point out to you and the medical members of the Committee the extreme undesirability of this mixture being added to bread, for, as you are aware, phosphorus and its compounds are spinal and brain stimu- lants and the constant stimulation of these centres with phosphorus is clearly contra-indicated. In my opinion the use of this adulterant should be most strongly put down, as the adulterated loaf is harmful in every way, especi- ally to those with neurotic temperaments.” The cardinal error of this statement is that the medicinal properties of phosphorus are ascribed to the calcium phosphate, whereas therapeutically they have nothing in common. Because sodium would take Are in the mouth and chlorine would instantly suffocate, and therefore both are regarded as virulent poisons, it would be just as logical to argue that sodium chloride or common salt is a most harmful substance, and therefore its use should in every case be regarded as an adulterant. Whatever evidence might be forthcoming that this substance is harmless and even beneficial, and however fully it might be accepted by a Court of Justice, it would now be commercially impossible for any miller or baker to declare the admixture of calcium phosphate in the district where this report is circulated and accepted. CHAPTER XXI. THE NUTRITIVE VALUE AND DIGESTIBILITY OF BREAD. 640. Nutrition and Food. — Nutrition may be regarded as the process of supplying the materials necessary in order to effect the growth and development of living organisms, and the maintenance in a healthy con- dition of those organisms when fully developed. The human organism is for practical purposes the only being whose requirements need be here considered. Food may be regarded as that which when taken into the body provides material for its growth and development, the reparation of the waste of its tissues, the production of heat, and the energy necessary both for internal and external muscular work. In other w'ords food com- prises those substances which are available for purposes of nutrition. Food substances or “ nutrients ” are derived from the animal, vegetable, and mineral kingdom. They belong to the following chemical groups of substances — proteins and closely allied bodies, as sclero-proteins (gelatin), carbohydrates, fats, and mineral matters, especially those containing lime, potassium, sodium, phosphorus, and chlorine, also water. An old classifi- cation of nutrients was into flesh formers, as proteins ; heat-formers, as carbohydrates and fat ; and bone-formers, as calcium phosphate. A more modern arrangement is into the two groups of tissue-formers and work and heat producers as under : — Tissue- formers. Work and Heat Producers. Proteins. Proteins. Mineral Matters. Sclero-Proteins. Water. Carbohydrates. Fats. (?) Mineral Matters and Water. The proteins are distinguished from among the other organic constituents of food by their being capable of exercising both the above-mentioned functions of nutrition. In estimating the nutritive value of foods they are subjected to tests of three kinds : — I. Chemical analysis, by which the proportions of the various constitu- ents are determined. II. The heat produced by their combustion in oxygen, this being a measure of their heat and energy producing capacity. III. Physiological tests, in which their degree of capacity for utilisation by the body is measured. The general composition as ascertained by chemical analysis need not be further enlarged on here. 641. Heat of Combustion. — This requires some further description. Excluding the mineral matters and water, the other food constituents are all combustible, and each variety evolves a definite amount of heat when completely burned, depending on its composition. The unit measure of heat is that which is required to raise I gram of water from 0° to 1° C., and this is called a “ calorie.” For food valuations a larger unit is convenient ;; 525 526 THE TECHNOLOGY OF BREAD-MAKING. and accordingly, that selected is the large or kilo -calorie, which is the amount of heat necessary to raise 1 kilogram (1,000 c.c.) from 0° to 1° C. The kilo-calorie or large Calorie is indicated by its being spelled with a capital C. When burned with an excess of oxygen the whole of the con- stituents of any food are completely oxidised ; but when consumed in the body, they are finally excreted in only a partially oxidised state, and there- fore some allowance must be made for the heat still remaining unused in these bodies. That having been done, the amount of energy liberated by any food follows just the same laws as though it were burned in the ordinary way. The heat liberated within the body by the following substances is, according to Hutchison : — One gram of Proteins . . . . . . . . 4T Calories. ,, ,, Carbohydrates . . . . . . 4T ,, ,, ,, Fat . . . . . . . . 9-3 ,, The energy value of a food is easily calculated from its analysis. If the percentages of proteins and carbohydrates are multiplied by 4T, and that of the fat by 9*3, the sum of these numbers gives the energy in Calories of the food itself. Thus if a sample of flour gives the following results on analysis, the heat energy is as shown : — Per cent. Factor. Heat of Combustion. Protein 11-08 x 4-1 = 45-428 Carbohydrates . . . . . . 76-85 x 4-1 = 315-085 Fat 1-15x9-3= 10-695 Kilo-Calories per 100 grams .. .. .. .. 371-208 ,, ,, ,, 1 gram . . . . . . . . 3-71208 Gram-calories per 1 gram . . . . . . . . 3712-08 Snyder, to whose results a somewhat extended reference follows, returns his “ Heat of combustion '' in terms of the complete oxidation obtained by burning in oxygen, and without any deduction for incomplete combustion in the body. He uses therefore the following factors for calculating the heat of combustion from the analysis. They are applied to the same analysis of flour. Per cent. Factor. Heat of Combustion. Protein .. .. .. .. 11-08 x 5-9 = 65-372 Carbohydrates . . . . . . 76-85 x 4-2 = 322-770 Fat 1-15x9-3= 10-695 Kilo-Calories per 100 grams . . . . . . . . 398-837 ,, ,, ,, 1 gram . . . . . . . . 3-988 Ditto determined direct on the flour . . . . 4-032 642. Digestibility. — In making physiological tests this term is used as meaning the measure of tlie total amount of the food utilised or absorbed by the body. The principle of the determination is the weighing the whole of the food of known composition eaten during a certain period, and the estimation of the weight and composition of that which is ejected in the excreta. The difference is the amount absorbed. The more popular meaning attached to the word digestibility relates to the comparative ease or discomfort with which the food passes through the stomach. In view of the use of the word in this latter sense, Hutchison has proposed to use the word “ absorbability '' instead of digestibility when dealing with the proportion of a food which is absorbed or utilised by the body. But as most writers still employ digestibility as synonymous with absorbability it will be used in that sense in this work. THE NUTRITIVE VALUE OF BREAH. 527 643. Amount of Food required. — To discuss this question adequately would require much more space than can possibly be devoted to it here. The student is therefore referred to Food and Dieteticd by Hutchison for full information on this subject. From his most interesting book the follow- ing summary is quoted : — “ One may sum up the standard amounts of the different nutritive con- stituents required daily thus ; — Protein . . . . . . . . . . . . 125 grams. Carbohydrate . . . . . . . . . . 500 ,, Fat . . . . . . . . . . . . . . 50 ,, These would yield the following amount of energy in Calories : — Protein 125 X 4-1 = 512-5 Carbohydrate . . . . . . 500 x 4-1 = 2050-0 Fat 50 X 9-3 = 465-0 Total . . . . . . . . . . = 3027-5 Calories. Or, in terms of carbon and nitrogen : — 125 grams of Protein = 20 grams N and 62 grams C. 500 ,, ,, Carbohydrate = 200 ,, ,, 50 ,, ,, Fat = 38 ,, ,, Total = 20 grams N and 300 grams C. Such a standard may be regarded as the minimum for a man of average build and weight, and doing a moderate amount of muscular work. . . . In such standards the ratio of protein to carbohydrates and fat taken to- gether is of some importance. It is called the nutritive ratio. If I part of fat be counted as 2-25 parts of carbohydrate, the nutritive ratio . . . is as I to 4-9. In this ratio we have an index of the proportion which the building material of the diet ought to bear to its purely energy-yielding constituents."'* For the figure 4-9, that of 5-3 more closely represents the average ratio of a number of authorities. In the diet of a child the ratio should be approximately as 1 to 4-3. 644. Nutritive Ratio of Wheat Products. — The following figures of analysis are taken from those of spring and winter American wheats and their products : — ( Protein. Carbohydrates. Fat. Xutritive Ratio Spring Wheat . . 14-35 70-37 2-74 1 : 5 -3 Baker’s Flour . . 14-88 69-99 2-00 1 : 5 -0 Patent Flour 12-95 73-55 1-45 1 : 5 -9 Bran 16-28 56 21 5-03 1 : 4-1 Germ 33-25 35-19 15-61 1 : 2-1 Winter Wheat . . 12 43 71-67 2-46 1 : 6 -2 Baker’s Flour . . 13-13 71-52 1-77 1 : 5 -4 Patent Flour 10-18 78-28 1-05 1 : 7 -9 For the moment, neglecting the waste through variations in digestibility, spring wheat and spring wheat baker’s flour contain sufficient protein to comply with the standard nutritive ratio. Bran contains a large excess of protein, while that in germ is approximately two and a half times as much as required by the standard. Evidently a mixture of germ and white 528 THE TECHNOLOGY OF BREAD-MAKING. flour may be made in such proportions as to comply exactly with the nutri- tive ratio. The spring patent is slightly deficient in protein, but the de- ficiency is but small. The winter wheat and its products are all lower in protein matter. An interesting point is that the spring patent flour has very nearly the same ratio as the baker’s flour from winter wheat. The baker’s flours have a slightly higher nutritive ratio than the wheats from which they were obtained, while the ratio is definitely lower in the case of the patent grades. English wheats, and the general average of wheats milled in England, have a lower protein content than spring American wheat. From analysis of a number of representative English millers’ flour the- following figures have been deduced : — Moisture Proteins . . Carbohydrates . Fat Ash Cellulose 14*0 per cent. ILO „ 72*7 „ L5 „ 0-5 ., ? ? 0-3 „ ICOO Nutritive ratio.. .. .. .. .. 6-9 Viewed from the standpoint of a perfectly balanced food, such flour is markedly deficient in fat, and slightly deficient in proteins. In an actual mixed diet, these deficiencies are made up by the addition of butter to- bread, and the consumption therewith of such substances as lean meat and cheese. 645. Relative Digestibility of White and Brown Bread, Lauder Brunton. and Tunnicliffe. — The results of a research by these gentlemen were pub- lished in 1899. They selected the best white bread of a West End London baker, and a whole-meal bread, i.e., one made from the whole of the wheat granule. The writers state that chemically the chief substances in which white bread is deficient as compared with browm are ash (consisting mostly of phosphates of potash, lime and soda), nitrogenous matters, fatty matters, and cellulose. The results of analyses of the two breads selected for experiment are set out in Table I, page 529. In order to determine their digestibility in saliva, a sufficiency of that fluid was carefully collected, and filtered, and the following mixtures made- with No. I. white bread, and No. II. brown bread, respectively : — Bread, white and Brown respectively . . . . 2 grams. Distilled Water . . . . . . . . . . 30 c.c. Mixed Saliva and Distilled Water, equal volumes 30 c.c. The mixtures were maintained at from 35-40° C. for 30 minutes, then boiled, and the sugar in each mixture estimated. In order to determine their relative pancreatic digestibility, the following mixtures were made : — Bread, White and Brown respectively . . . . 2 grams. Benger’s Liquor Pancreaticus . . . . . . 15 c.c. Distilled Water . . . . . . . . . . 45 c.c. A few drops of a saturated solution of sodium carbonate. Tliese mixtures were maintained at 37° C. for 7 hours, then boiled, and sugar estimated. The results are shown in Table II, page 529. From tliese tables it will be seen that the starch of white bread is much more rapidly and completely acted on than that of brown bread. Experi- THE NUTKITIVE VALUE OF BREAD. 529 merits were next made on the digestibility of the nitrogeneous constituents. For this purpose they were submitted to Gastro- Pancreatic digestion. The Table I. I’ercentage Composition of i Constituents. Bread as Supplied. Water-Free Breads. | i White Bread. Brown Brea 1. White Bread. Brown Bread. Water Per cent. 39 10 Per cent. 40-18 Per cent. Per cent. Dry -Substance 60-90 59-82 — — Total Ash . . 0-59 i 1-88 0-97 3-14 Phosphoric Acid . . 0-16 0-51 0-26 0-85 Soluble Matter 4-73 i 7-54 7-77 12-60 Nitrogen 1-32 1-25 2-17 2-09 Albumin, calculatedfrom Nitrogen ^ 8-25 7-87 13-54 13-16 Pure Albumin ^ . . 7-34 7-86 12-05 13-15 Soluble Nitrogenous Matter ^ 0-61 ^ 0-73 1-00 1-22 Starch and Saccharine Matters, etc. 51-85 49-44 — — Starch 38-45 39-18 63-13 65-49 Sugar (Maltose) 1-19 1-77 1-95 2-96 Dextrin 0-84 0-71 1-38 1-19 Cellulose 0-24 1-06 0-39 1-68 Fat . . 0-21 0-63 0-34 1-05 Acidity (Lactic Acid) 0-19 0-29 — — Loss of water in fifteen days 9-23 ! ^ Total proteins. ^ Insoluble proteins. ^ goluble proteins and other nitrogenous bodies. Table II. Particulars. No. I. White Bread. No. II. Brown Bread. Percentage of total possible Sugar calculated from Starch, on Dried Solids of Bread 70-14 72-76 Actual formed Sugar — (a) Saliva, half hour 21-64 9-99 [h) Pancreas, 7 hours 33-07 19-75 Percentage of actual formed Sugar to possible Sugar — (a) Saliva, half-hour 30-85 13-73 {h) Pancreas, 7 hours . . 51-42 27-14 following mixtures were made : — Bread, White and Brown respectively . . . . ' 2 grams. Benger’s Liquor Pepticus . . . . . . . . 10 c.c. Distilled Water . . . . . . . . . . 50 c.c. These were maintained at 37° C. for 10 hours, then boiled and filtered. The residue was then submitted to pancreatic digestion, in the same manner as before described, for 6 hours, and again filtered. The residual nitrogen was then determined and calculated into proteins. The difference between this figure and the quantity originally present in the bread was regarded M M 530 THE TECHNOLOGY OF BREAD-MAKING. as having been digested. Another pair of samples was subjected to pan- creatic digestion only, in the same manner as before, and the residual pro- teins determined after 11 hours’ treatment. The following table shows the results : — Particulars. White. Brown. Percentage of Nitrogenous Matter digested, cal- culated to total Nitrogenous Matter in Water- free Breads — Per cent. 1 Per cent. {a) Gastro-pancreatic Digestion — Ten hours Gastric Six hours Pancreatic ]- 74-89 60-71 1 (6) Pancreatic alone, II hours 79-38 69-81 From this table it will be seen that in tlie case of the gastro-pancreatic digestion of white bread, 14 per cent, more of the nitrogenous constituents Avere digested than in the case of brown. In pancreatic digestion the excess of nitrogenous matter digested in white bread amounts to nearly 10 per cent. The Avriters next experimented on the cellulose ; as might be expected they found a much greater residue from the brown bread, which was in thick flakes ; Avhereas that from the Avhite bread was in very small thin flakes. They regard the cellulose of the former as producing an irritant action upon the intestines, by which the sluggish intestines may be stimu- lated up to the normal condition. On the other hand by causing excessive peristalsis in irritable intestines, digestion may only partially take place, and both a loss of nutritive material and diarrhoea may ensue. The wTiters are of opinion that probably, in fact almost certainly, all the salts and all the fat in bread are absorbed, and therefore in this respect at any rate, if the fact that brown bread may remain for less time in the alimentary canal is neglected, brown bread is superior to white. From the above results they formulate the folloAving conclusions : — 1. White bread is, weight for weight, more nutritious than brown. Therefore, it appears the preference given by operatives in large towns for Avhite bread has, to a certain extent, a sound physiological basis. 2. In the case of people with irritable intestines, Avhite bread is to be preferred to brown. 3. In the case of people with sluggish intestines, broAvn bread is prefer- able to white, as it tends to maintain regular peristaltic action, and ensure regular evacuation of the bowels, with all its attendant advantages. 4. In cases Avhere the proportion of mineral ingredients, and especially of lime salts, in other articles of food or drink is insufflcient, brown bread is preferable to white. It is possible that in the case of operatives living chiefly upon bread and tea, the preference for white bread which obtains in large towns may be responsible, in part at least, for the early decay of the teetli of those living on such a dietary. 5. An abundant supply of mineral constituents is especially required in pregnant and suckling women and in growing children, in order to supply material for the nutrition of the foetus, the constituents of the milk, and for the growth of the tissues, especially of the bones. In such cases, if mineral salts, especially those of calcium, are not supplied by other food- stuffs, drinks, or medicines, brown bread is preferable to white. G. If the dietary is insufficient in fat, or if the patient is unable readily THE NUTRITIVE VALUE OF BREAD. 531 to digest fat in other forms, brown bread may possibly be preferable to ■white. {Bartholomew’s Hospital Reports, vol. xxxiii.) 646. Bread : Digestive and Nutritive Properties, Jago. — In 1899, a com- munication was made by one of the authors to the National Association of Master Bakers of the United Kingdom, under the above title. It con- sisted of the results obtained by submitting various samples of bread to artificial digestion in the following manner ; — Method of experiment. — As digestive agents. Armour’s standard pepsin and pancreatin were employed. Definite weights of the crumb of bread, water, acid and pepsin were taken ; these were rubbed down into a pulp, and transferred to a flask, and then kept at body temperature (98° F. = 36-6° C.) for 3 hours. At the end of that time definite quantities of alkali and pancreatin were added and the digestion continued for an additional 5 hours. The following determinations were then made In soluble portion. — (1) Peptones, or fully digested proteins ; (2) pro- teoses, or partly digested proteins ; (3) proteins simply dissolved ; (5) maltose and dextrin as results of carbohydrate digestion ; (8) phosphates obtained in soluble form. In imdissolved portion. — (4) Undissolved proteins ; (6) starchy matter undissolved. This was determined by separating the branny matter by means of a very fine sieve. (7) Branny matter. Description of hreids examined. These were : — I. Whole-meal bread. — This was a plain whole-meal loaf made from a rather coarse meal. II. Malt digestive bread. — This was made from a mixture of white flour, fine whole meal, malt extract, and no chemicals for raising purposes. III. Best quality white bread. — Baker’s ordinary loaf. IV. Best quality white bread. — Baker’s ordinary loaf. V. Straight flour from all English wheat. — This was specially prepared by taking fine English whole-meal and hand dressing it through a fine sieve. This flour approximated as nearly as possible to an old-fashioned stone- milled and bolted flour from English wheat. VI. Malt digestive bread. — This was similar to No. II., except that it contained in addition cream of tartar and bicarbonate of soda. VII. Germ bread. — This was prepared from a mixture of white flour and wheat germ. No. I. is a sample of baker’s ordinary whole-meal bread. Nos. III. and IV. were samples of baker’s best bread made in the ordinary way of business. Nos. II., V., VI. and VII. were specially prepared representations of special types, but must not be regarded as examples of any particular proprietary articles. Composition of breads. — Analyses were made of the breads themselves with the results shown in the table on following page. The “ gross nutritive ratio ” is that of the proteins as against the whole of the other solid con- stituents taken as carbohydrates. The fat being reckoned as starch is under- valued, but this is roughly compensated by the cellulose, salts, etc., being reckoned as nutritive carbohydrates. In consequence, this figure must be regarded as only approximate. The total energy in Calories is also deficient through fat not being separately reckoned. The water of the white bread is considerably less than that of any of the others. One result of that is that although the proteins of whole-meal bread are more on the dried solids than are those of white bread, yet the percentage per weight of bread as sold and eaten is more with the white than the whole-meal bread. The proteins of the “ All English ” bread. No. V., are less than those of the baker’s ordinary bread. In the case of 532 THE TECHNOLOGY OF BREAD-MAKING. Constituents. I. Whole Meal. II. Malt Bread. III. White Bread. Natural. Dried. Natural. 1 Dried. Natural. Dried. Moisture . . 49-91 1 44-77 40-10 Proteins . . 6-29 12-55 6-40 11-58 i 7-06 11-78 Soluble Extract . . 8-84 17-65 15-56 28-17 11-92 19-90 Starch, Fat, etc. . . 34-96 69-80 33-27 60-25 40-92 68-32 100-00 100-00 100-00 100-00 100-00 100-00 Gross Nutritive ratio 7-0 7-0 7-6 7-6 7-5 7-5 Total Energy in Calories 210 4 420-0 232-0 420-0 251-6 j 420-0 lA". AA'hite Bread. 1 Y. All English. VI. Malt Bread. VII. Germ Bread. Natural. Dried. Natural. Dried. Natural. Dried . Natural. Dried. Moisture . . 39-64 44-10 41-10 45-40 Proteins . . Soluble Extract, Starch, 6-99 11-8 6-55 10-93 6-33 10-74 10-36 18-95 etc. 53-37 88-42 49-35 89-07 57-57 89-26 44-24 81-05 100-00 100-00 100-00 100-00 100-00 100-00 100-00 100-00 Gross Nutritive ratio . . 7-6 1 7-6 8-1 8-1 ! 8-3 8-3 4-3 1 4-3 Total Energy in Calories 253-5 420-0 234-8 420-0 247-4 o 6 229-3 420-0 the whole of the breads Avith but one exception, the gross nutritive ratio- falls below the requirements, 5*3, of a well-balanced food. In the germ bread, proteins are in considerable excess, and bread of this kind acts as a sparer of more expensive protein foods. Results of Digestion . — Before giving these it must be mentioned that the first tliree tests were made together. It was subsequently thought desirable to make the other tests, numbered V., VI. and VII. Unfortunately, the original stock of pepsin and pancreatin Avas entirety exhausted betAveen the tAvo sets of experiments, and a fresh supply was obtained direct from the manufacturers. In order to test the ncAV pepsin and pancreatin, another test Avas made on the best white bread. No. IV. sample being of the same make and quality as No. III. Consequently, the members of the first group, I., II. and III., and of the second group, IV., V., VI. and VII., are comparable among each other ; but members of the one group cannot be directly compared AAuth the other group. Nos. HI. and IV. are practically the same bread digested under the same conditions, except that different samples of the same make of pepsin and pancreatin were used in each case. Taldng the proteose and peptone together there is not much difference in their activity ; but the No. II. samples possess greater peptonising power and convert much more of the proteose completely into peptone. No. II. samples also shoAV slightly more starch-converting poAver. In the first table on page 533, the digestion of the proteins only is considered, and the results are Avorked out in such a Avay as to sIioav AA^hat becomes of 100 parts of protein matter. In examining these results, the starting point must be samples III. and IV., since these are the connecting links betAveen the tAvo sets of experi* ments. In No. III., there is less protein left absolutely unacted on, but the digestive process has not been carried so far as Avith No. IV. Still THE NUTRITIVE VALUE OF BREAD. 533 Protein Digestion in Terms of IOO Parts of Protein. Constituents. I. II. III. IV. V. VI. VII. Digested, Peptones 35*46 44;68 48-C2 81-28 79-31 80-66 83-26 Partly digested, Proteoses 48-79 36-0*2 47-28 9-62 5-39 8-44 5-84 Dissolved only. . 0-40 1-20 1-10 3-10 1-20 1-20 1-40 Undissolved 15-35 18-10 2-70 6-00 14-10 9-70 9-50 1 100-00 100-00 100-00 100-00 100-00 100-00 1 100-00 there are only 2-7 and 6-00 per cent, respectively of protein matter un- attacked. Comparing whole-meal, No. I., with best white bread, No. HI., the quantity of assimilated protein in the latter is greater along the whole line. The peptones are much higher, the proteoses are about the same, while 15*35 against 2*70 per cent, remains unacted on. The most inter- esting comparison in the second series is between No. IV. best bread, and No. V. from all English wheat flour, prepared so as to resemble as closely as possible an old-fashioned home-made loaf from country stone-ground flour. Examination shows that in the case of the best white bread there is more of every form of digestive protein than in the case of the darker old-fashioned loaf, while 14 per cent, remains unacted on as against 6 per cent, in the other. Nos. II. and VI. are malt extract “ digestive '' breads ; so far as proteins are concerned, these do not greatly differ from whole- meal. No. VII. was prepared from a germ flour ; the digestibility of the proteins is very nearly the same as that of white bread. Taking the whole series, the baker’s best white bread has the highest degree of protein digesti- bility. In the next table are shown the products of digestion of 100 parts of the bread as obtained from the baker. For the nutritive ratio, the peptones, proteoses, and simply dissolved proteins, are all taken together. The carbo- Products of Digestion expressed in Percentages of Bread Employed. Constituents. I. II. III. ly. V. VI. VII. Proteins - — - (1) Digested, Peptones 2-23 2-86 3-45 5-68 5-19 5-10 8-48 (2) Partly digested, Pro- teoses 3-06 2-30 3-34 0-67 0-36 0-54 0-60 (3) Dissolved only 0-03 0-08 0-08 0-22 0-08 0-08 0-15 (4) Undissolved 0-97 1-16 0-19 0-42 0-92 0-61 0-96 Carbohydrates — (5) Digested, Maltose, etc 32-49 36-50 43-49 46-53 43-12 42-41 37-20 (6) Starchy Matter, un- dissolved . . 6-65 9-55 9-35 6-84 5-28 7-98 5-43 (7) Branny Matter, un- dissolved . . 4-66 2-78 Nil Nil 0-95 2-18 1-78 Water 49-91 44-77 40-10 39-64 44-10 41-10 45-40 100-00 100-00 100-00 dOO-00 100-00 100-00 100-00 Nutritive ratio . . 6-1 7-0 6-3 7-1 7-6 7-4 4-0 Energy in Calories 158-8 175-3 211-5 223-0 204-7 202-1 195-0 Calculated Fat . . 1-25 1-10 0-72 0-72 1-10 1-18 5-50 Energy in Calories allow- ing for Calculated Fat 170-4 185-5 218-2 229-7 1 214-9 213-0 246*1 534 THE TECHNOLOGY OF BREAD-MAKING. hydrates are taken as the whole of the remaining digested matter, and include the mineral salts. The fat is excluded altogether in the calculation, but the quantity is very small except in the case of the germ bread, and with that there must be a considerable deficit of carbohydrate. This is provided for in a subsequent separate calculation. The energy is that calculated from the dissolved constituents. Correction for Fat . — Neither the Nutritive ratio, nor the Energy in Calories were included in the original paper, but have been added when preparing the present work. The fat was not determind in any of the breads, but from the average composition of the meals and flours used can be calcu- lated with fair accuracy. The approximate figure thus obtained is given at the foot of the table, and then the Energy in Calories allowing for the calculated fat. It is assumed that this latter would be entirely absorbed in the process of digestion. In the foregoing table many of the results are modified, because they are affected not only by the degree of digestibility, but also by the actual quantity of each constituent present. A point frequently overlooked in comparing the nutritive qualities of different t 3 q)es of bread is that of the proportion of water commonly present. It may be fairly assumed that the baker will give respectively appropriate quantities of water to each type of meal or flour to make it into bread, and in the case of the loaves now under consideration the percentage varies from 49*91 with the whole- meal bread to 39*64 in the white loaf. These figures are borne out by general experience, and hence when comparing the composition of whole-meal and flour breads against each other, it must be remembered that the greater quantity of water necessary to make the whole-meal loaf will correspond- ingly lower its comparative nutritive value. In examining the results, the two white bread samples must again be taken as a starting point. Grouping the digested and partly digested proteins together, there is 6*79 in the one as against 6*35 per cent, in the other, which is no very great difference. In starchy matter. No. IV. has a slight advantage, 46*53 as against 43*40 per cent. Branny matter was of course absent from these samples. Com- paring the whole-meal No. I. against No. III., there is a total of digested and partly digested proteins of 5*29 in the former against 6*79 in the latter. Digested starchy matter is also low, being 32*22 against 43*40 per cent. As whole-meal bread contains a low proportion of starch to begin with, it is only natural that a comparatively small amount should remain un- digested, viz., 6*65 as against 9*55 per cent. Counterbalancing this there is 4*66 per cent, of branny matter, against nil in the white bread. This residual branny matter gave, on analysis, 8*32 per cent, of protein, being roughly rather over one-half of that contained in bran in its natural con- dition. Taking in the next place No. IV., best white bread, against the special old-fashioned loaf. No. V., there is in No. IV. more of peptone, pro- teose and dissolved protein than in No. V., the total being 6*57 against 5*6S per cent, in the latter. There is more than double as much undissolved ]wotein in No. V., but this alone does not make up the difference. The explanation is that No. V. contained less protein to start with, and of that less amount a smaller proportion is digested under the same conditions. No. V. also shows less starch digestion. Turning next to the two malt extract breads, they fall slightly below the best white loaves in both protein and starch digestibility. Taking Nos. II. and VI., they differ principally in that cream of tartar and soda have been used in the preparation of the latter. So far as an indirect comparison can be made between them, there does not seem to be evidence that these chemicals have exercised a retard- ing effect on digestion. On referring to No. VII., it wiW be seen that the THE NUTRITIVE VALUE OF BREAD. 535 presence of germ has very considerably increased the percentage of protein present, and hence the amount of peptone yielded is represented by a very high figure, 8-48 per cent. The digested starch is not so high, but then this is a natural result of the preparation containing starch in low propor- tion. Under the heading of branny matter, the figure U78 is given ; but this in reality is not all bran, the major portion consists of the white intact cellulose skeletons of the germs themselves. In nutritive ratio the whole of the breads except the germ show a deficiency of protein. Comparing|.the two most important types, whole-meal and white bread, the whole-meal is 6T as against 6-3 and 7T respectively. The low figure with the whole meal is not due, however, to excess of protein, but to a deficit of carbo- hydrate. The two best white breads show a greater amount of calorific energy of the actually digested constituents than either the old-fashioned loaf (No. V.) or the whole-meal. No. I. The last is in fact the least valuable in terms of energy of the whole series. As a result of its fat, the germ bread heads the list in point of energy. {National Association Review, 1899, XVI. 349. 647. Studies in Digestibility and Nutritive Value of Bread ; Atwater, Woods, and Snyder. — A most important, systematic, and exhaustive study of this subject has been made by the above investigators, under the auspices of the United States Department of Agriculture. Supervision was exercised by Atwater and Woods, the actual experiments being made by Snyder at the University of Minnesota, U.S.A. Snyder's investigations extend over the years 1899-1905, and are described and reported in Bulletins Nos. 101, 126 and 156 of the U.S. Department of Agriculture. Snyder has specially directed his attention to the comparative values of different kinds of flour or meal from the same wheat, since unless that precaution be taken, the differences may be due to the intrinsic value of the entire wheats rather than the special type of meal or flour obtained therefrom. He therefore regards it as evident that a fair comparison of the nutritive values of the different kinds of flour — graham, entire-wheat, and standard patent — can be made only when the three kinds of flour have been milled from the same lot of wheat. This was done in the investigations here reported, a hard, Scotch Fife spring wheat being used. The importance of the subject, it is believed, has justified this systematic inquiry. It is to be particularly observed that the “ graham " flour is unbolted wheat meal, while the so- caUed “ whole-wheat," or entire-wheat flour, contains all of the kernel except a portion of the bran. The “ patent " and “ clear grade " flours contain practically none of the bran or episperm and very little of the germ or embryo of the wheat kernel. From the above wheat the following samples were obtained and first submitted to analysis : — No. 1. First patent flour ; produced by the roller process of milling. This is the highest grade of patent flour manufactured. The gluten from this flour has a greater power of expansion than that from any other grade, and the flour also absorbs the most water and produces the whitest and largest sized loaf of bread. No. 2. Second patent flour, sometimes called standard Minneapolis patent flour. It is similar to first patent flour, but the bread produced is a shade darker in colour, and the gluten does not possess quite so high a power of expansion. No. 3. Standard patent flour is made up of the sum of the first and second patent grades and the first clear or bakers' grade of flour, and is the ordinary bread flour most frequently found on the market. It is used in this investigation as the standard for comparison with the entire-wheat 536 THE TECHNOLOGY OF BREAD-MAKING. and graham flours. About 72*6 per cent, of the screened wheat is recovered as standard patent flour. [It will be noticed that the “ standard patent flour ” is practically a straight grade flour, i.e., the whole of the flour of the wheat.] No. 4. First clear grade flour. After the first and second grades of patent flour are removed, about II -8 to 12 per cent, of the first clear grade flour is obtained, which contains slightly more protein than either the first or second patent flour. The protein, however, does not contain gliadin and glutenin in the right proportions to produce so good a quality of bread as the patent grade flours. No. 5. Second clear or low grade flour. After the standard patent flour has been removed there is obtained about 0-5 per cent, of flour called second clear or low grade, which contains a high percentage of protein. The gluten, however, is of poor quality for bread-making purposes. No. 6. “ Red dog '' flour. This is the lowest grade of flour produced. It is dark in colour and has but little power of expansion. It is secured largely from the germ or embryo and adjacent portions of the wheat, and coiRains a relatively high percentage of protein. “ Red dog '' flour pro- duces a small and dark-coloured loaf of bread as compared with flour of better quality. No. 7. Middlings or shorts. About 11-6 per cent, of the cleaned wheat is recovered in middhngs, which consists of the fine bran that has been more completely pulverised. When this product contains a large part of the germ it is much richer in protein than ordinary shorts and is called shorts middlings. The term middlings, as used in this sense, should not be con- fused with the same term applied to the material obtained when wheat is milled by the old process. The middlings of the old process are now reduced and recovered in the various grades of patent flours. No. 8. Bran. This is the episperm or outer covering of the wheat kernel. No! 9. Entire-wheat flour. This is the product obtained by removing a portion* of the bran and then grinding the remainder of the wheat kernel. The flour is of a coarser texture than the patent and clear grades. Entire- wheat flour is sometimes called “ purified graham or ‘‘ natural " flour. No. 10. Graham flour. This is the entire-wheat kernel (bran and all) ground into meal. The presence of the bran prevents the fine grinding of the material, and particles of the bran are apparent when the flour is ex- amined. Graham flour is practically wheat meal. No sieves or bolting cloths are employed in its manufacture, and many coarse particles of un- pulverised material are present in the product. No. 11. Cleaned wheat, scoured and polished for milling. This is a hard Scotch Fife spring wheat, plump, and of good quality, weighing 60 lbs. per bushel. The sample analysed was ground in the laboratory in a Maercker mill. All of the grades of flour and the various products given in the list of samples were obtained from this wheat. ^ No. 12. Gluten flour. This is a flour containing as high a percentage of protein as it is possible to secure by the ordinary roller-process milling. It is not composed entirely of gluten, but simply contains a high percentage of this material. No flour can be composed entirely of gluten. The table on page 537 gives the results of analysis of the foregoing pro- ^^^The heat of combustion or energy was determined in a bomb calori- meter, as described in Chapter XXVii of this work. When calculated from tlie constituents the following factors were employed Protein. . • • • • • . . 5-9 Calories per gram. Fat . . . . • • • • . . 9-3 „ ,, „ Carbohydrates . . • • . . 4*2 „ „ „ THE NUTRITIVE VALUE OE BREAD. 537 Composition, Acidity, and Heats, of Combustion of Flours and OTHER Milling Products of Wheat. 1 Sam- Carbo- Phos- i Acidity calcu- Heat of Combus- tion per gram. i pie 1 No. Milling Product. Water. Protein (NX 5-7). Fat. liy- drates. Ash. phoric Acid. lated as Lactic Acid. 1 Calcu- 1 lated. j Deter- mined. P. ct. P. ct. P. ct. P. ct. P. ct. P. ct. P. ct. Calories.’ Calories. I 1 First Patent Flour . . 10-5.5 11-08 1-15 76-85 0-37 0-15 0-08 3-989 ! 4-032 Second Patent Flour 10-49 11-14 1-20 76-75 0 42 017 0 08 i 3-992 4-006 I ' Straight or Standard Patent Flour 10-54 11-99 1-61 75-36 0-50 0 20 0-09 4-022 4-050 i 4 1 First Clear Grade Flour 10-13 13-74 2-20 73-13 0'80 0-34 0-12 4-087 4-097 1 5 Second Clear Grade Flour 10-08 15-03 3-77 69-37 1-75 0-56 0-27 4-153 1 4-267 : 6 “ Red Dog ” Flour 9-17 18-93 7-00 61-37 3-48 — 0-59 4-349 4-485 7 Shorts 8-73 14-87 6-37 65-47 4-56 — 014 4-219 4-414 8 Bran 9-99 14-02 4-39 65-54 6-06 2-20 0-23 3-988 4-198 9 Entire- wheat Flour 10-81 12-26 2-24 73-67 1-02 0-54 0-32 4-026 4-032 10 Graham Flour 8-61 12-65 2-44 74-58 1-72 0-71 0-18 4-123 4-148 11 Wheat ground in Laboratory- 8-50 1 12-65 : 2-36 74-69 1-80 0-75 018 4-114 4-140 12 Gluten Flour 8-57 16-36 3-15 70-63 1-29 0 14 — — Digestion Experiments . — The most important part of Snyder’s researches consisted of the elaborate digestion experiments made. The subjects were young men in good health, designated in these experiments as Nos. 1, 2, 3, and 4. In so far as possible the experiments were alike, except as regards the kind of flour from which the bread eaten was made. All the food con- sumed and faeces excreted were weighed and samples were analysed The separation of the faeces for the experimental period was made by the use of charcoal, which was given to the subjects in capsules with the last meal before and the first meal after each period. The digestibility of the bread and milk diet as a whole was measured by the difference between the total nutrients in the diet and those in the faeces. Then, by assuming certain factors for the digestibility of the nutrients in the milk, the digestibility of those in the bread alone was estimated. The following is a detailed record of one of these experiments : — “DIGESTION EXPERIMENT No. 162. Kind of food. — Bread, made from standard patent flour, and milk. Subject . — Student No. 2 ; 24 years of age, with average amount of exercise. Weight . — At the beginning of the experiment, 140 lbs ; at the close, 139 lbs. Duration . — Two days, with six meals, beginning with breakfast, April 5, 1899. During this experiment, the details of which are given in the flrst table on page 538, the subject eliminated 1,390*3 grams urine, containing 1*82 per cent., or 25*3 grams, nitrogen. The average nitrogen balance per day was therefore as follows : Income in food, 10*8 grams ; outgo in urine, 12*7 grams, and in faeces, 0*9 gram ; implying a loss of 2*8 grams nitrogen, corresponding to 17*5 grams protein. The total heat of com- bustion of the urine as determined was 168 Calories.” Fiom the results of twelve such experiments the second table on page 538 was computed, the nutritive value of the milk being calculated and allowed for. 538 THE TECHNOLOGY OF BREAD-MAKING. Results of Digestion Experiment No. 162. Sam pie No. Weight of Ma- terial. Protein (NX 6-25). Fat. Carbohy- drates. Ash. i Heat of Combus- tion. Grams. 1 Grams. Grams. Grams. Grams. Calories. Food consumed — 53 Bread 876-0 67-9 7-8 410-9 2-8 2,146 54 Milk 2,100-0 66-2 97-2 105-0 14-7 1,664 Total — 134-1 105-0 515-9 17-5 3,810 56 Faeces (water-free) Estimated Faeces from 40-3 i 11-3 8-6 10-6 9-7 208 1 Food other than Bread — 2-0 4-9 2-1 — 72 Estimated Faeces from i Bread . . — 9-3 3-7 8-5 — 136 ! Total amount digested. . Estimated Digestible Nu- — 122-8 96-4 505-3 7-8 . 3,602 I trients in Bread — 58-6 4-1 402-4 — 2,010 1 Per cent. Per cent. Per cent. Per cent. Per cent. Co-efficients of digestibility of total Food . . Estimated Co-efficients of — 91-6 91-8 1 97-9 44-6 94-5 digestibility of Bread Proportion of Energy ac- — 86-3 52-6 97-9 93-7 tually available to body 90-5 In total Food — ■ — — — ! — In Bread alone “ 90-8 Digestibility of Nutrients and Availability of Energy of Bread alone. Experi- ment j No. Subject.! No. Kind of Food. Protein. Fat. Carbo- hydrates. Energy. 1 Per cent. Per cent. Per cent. Per cent. 161 1 Mffiite Bread (standard patent) 86-7 65-2 97-4 90-0 162 2 86-3 52-6 97-9 90-8 163 3 i .. ,, 1 ” 82-8 51.3 97T 89-5 j Average of 3 85-3 56-4 97-5 90-1 1 165 1 Entire-wlieat Bread . . 78-1 55-6 93-5 84 4 166 2 ! 83-9 48-1 94-6 86-1 1 167 3 79-1 63-6 94-1 86-1 i Average of 3 80-4 55-8 94-1 j 85-5 170 1 Graham Bread 81-0 67-8 88-1 81-8 171 2 ! 80-6 55-1 88-7 81-6 172 3 i 71-1 51-2 88-5 78-6 Average of 3 77-6 58-0 88-4 i 1 80-7 164 4 i White Bread (first patent) . . 90-5 — 98-0 92-8 168 4 ,, ,, (second patent) 91-4 — 98-7 1 93-5 ’ 169 4 ,, ,, (standard patent) 90-3 — 97-4 92.2 1 Average of 3 . . . . 90-7 — 98-0 1 92-8 THE NUTRITIVE VALUE OF BREAD. 539 Assuming that the averages for bread of different kinds given in tlie above table represent also the coefficients of digestibility of the nutrients in the different flours, the proportions of digestible nutrients in the flours may be calculated from their composition as given in the table on page 537 . Thus standard patent flour contains 11 -99 per cent, protein, 85-3 percent, of which is digestible ; the proportion of digestible protein in standard patent flour would then be (11-99 per cent, x 85-3 =) 10-2 per cent. In like manner the digestible carbohydrates and available energy may be calculated. Such calculations have been made for standard patent flour, entire-wheat flour, and graham flour on the basis of the composition of the flour as milled. The following table shows the results, as well as the total protein and carbo- hydrates, in comparison with the proportions of the nutrients and energy in the different flours. Proportions of Total and Digestible Nutrients and Available Energy in Different Grades of Flour as Milled. Flour. Protein. Carbohydrates. Heat of Com- bustion per gram. X X 5-70. X X 6-25 j XX5-70. X'x6-25. Total. Diges- tible. Total. 1 1 Diges- tible. Total. Diges- tible. Total tible. Total. Avail- able. ‘ Per ct. Per ct. Per ct. Per ct. Per ct. Per ct. ' 1 Per ct. Per ct. Calories. Calories. j Standard Patent . . j 11-99 10-2 13-14 11-2 75-36 73-5 74-21 72-3 4-050 3-650 1 Entire Wheat i 12-26 9-9 13-44 10-8 73-67 69-3 72-49i 68-2 4-030 3-445 j Graham 12-65 9-8 13-86 10-7 74-99 66-3 : 73-78| 65-2 4-150 3-350 From this table it will be observed that according to composition, the graham flour contained the largest proportion of protein and the largest amount of energy, while the standard patent flour contained the smallest proportion of protein, but a little more energy than the entire wlieat flour. According to the results of the digestion experiments, however, the propor- tions of digestible protein and the amount of energy actually available to the body were greater in the standard patent flour than in the entire-wheat or the graham flour. The latter contained the least digestible protein and available energy. A microscopic examination of the faeces showed that those derived ffom standard patent flour contained very small particles of disintegrated starch. The faeces from graham and entire-wheat breads contained masses of material containing wheat starch grains in practically the same form as in the original graham and entire-wheat flour breads. Artificial digestion experiments were also made, but as these agree with the results of previous investigations already described, their inclusion here is scarcely necessary. An extended series of digestion experiments was made in order to determine the degree of digestibility when a limited instead of a full ration of bread was given. The results indicate that when food is taken in small amounts it is more thoroughly digested than when taken in large amounts, and that it is possible for the digestive tract to be supplied with such a quantity of food that the highest degree of digestibility is not secured. On mixing starch with flour, the digestibility of the proteins is found to be modified. A fairly strong flour was taken and diluted by the addition of 20 per cent, of starch (80 -f 20 = 100). In this manner the equivalents of flours with a high and a low protein content were obtained. Digestion experiments were carried out with breads made from the two. The follow- ing table gives the digestibility of nutrients and availability of energy of the ordinary, compared with the starched bread, in percentages : — 540 THE TECHNOLOGY OP BREAD-MAKING. Protein. Carbohydrates. Energy. Ordinary bread, average of three ex- periments .. .. .. ..87-3 97-6 91-9 Starched bread, ditto.. .. .. 84*1 97-9 93-0 The two series of experiments indicate that a proportionally small amount of protein is less thoroughly digested than a proportionally large amount. In continuation of these investigations a similar series of digestion experiments was made with a hard spring wheat, characterised by a very high protein content, namely 15*5 per cent. The experiments lasted over four days instead of two, with similar results to those already recorded. In the next place experiments were made with the following soft winter wheats, and flours therefrom, of which analyses are given below : — No. 218. Cleaned soft winter wheat, from Goshen, Ind., prepared for milling, of good quality, and weighing 60 lbs. per bushel. The sample analysed was ground in the laboratory in a Maercker mill. No. 221. Mixed grade flour, ground from soft winter wheat. No. 218, and consisting largely of straight flour with some lower grades and a little germ. This sample was not strictly a straight grade flour, but more properly a blend. No. 222. Entire-wheat flour, ground from soft winter wheat No. 218, after removing a small amount of bran. This sample was different from the entire wheat used in former work with hard wheat ; it had more of the characteristics of graham. It was, however, more finely pulverised than the graham flours used in the previously described experiments. No. 268. Bran, from soft winter wheat No. 218. No. 237. Soft winter wheat, of good quality, from North Lansing, Mich., weighing 59 lbs. per bushel, cleaned and prepared for milling. No. 240. Straight grade or standard patent flour, milled from soft wheat No. 237. It should be classed as a high grade rather than as a straight - grade flour. It possessed good bread-making qualities, but required more thorough mixing and kneading than hard- wheat flours. No. 239. Bran, from soft winter wheat No. 237, obtained in milling flour No. 240. Composition of Wheats, Flours, and Offals, and of Bread used IN Digestion Experiments with Soft Wheat Breads. Sample No. Whence obtained. Water. Protein NX 5-7 Fat. Carbo- hydrates. Ash. Heat of Combus- tion per gram, deter- mined. 1 Soft Wheat — Per cent. Per cent. Per cent. Per eent. Per cent. Calories. 218 i Wheat from Indiana . . 8-09 13-10 1-52 75-38 1-85 4-090 219 Entire-wheat Flour 9-00 12-80 1-54 74-40 1-00 4-020 221 Mixed Grade Flour 10-30 12-30 0-93 75-94 0-53 4-010 237 Wheat from Michigan 10-25 12-34 1-35 74-23 1-83 4-000 239 Bran 8-74 14-90 4-41 05-78 0-11 4-108 240 Straight Patent Flour . . 10-97 10-92 0-50 77-15 0-40 3-799 241 ! Entire-wheat Flour 11-01 12-01 1-53 74-17 1-28 3-800 242 Graham Flour . . 11-23 12-24 1-41 73-27 1-85 3-900 208 Bran Bread made from — 10-94 10-72 4-42 01-20 0-72 — 223 1 Mixed Grade Flour. . 39-50 8-01 0-00 51-32 0-51 2-710 231 Entire-wheat Floux . . 39-50 8-53 1-02 49-49 1-40 2-040 244 1 Straight Patent Flour 30-87 7-59 0-38 54-07 0-49 2-010 251 ' Entire- wheat Flour. . 37-02 8-33 1-08 51-70 1-27 2-090 200 1 Graham Hour 38-12 , 8-30 0-87 51-20 1-45 1 i 2-020 1 THE NUTRITIVE VALUE OE BREAD. 541 No. 241. Entire-wheat flour, prepared from soft winter wheat No. 237. No. 242. Graham flour, obtained from soft winter wheat No. 237. No. 223. Mixed-grade flour bread. This was made of the flour from which sample No. 221 was taken. No. 231. Entire-wheat flour bread. This was made of the flour from which sample No. 219 was taken. No. 244. Straight patent flour bread. In making this bread flour was used from which sample No. 240 was taken. No. 251. Entire-wheat flour bread. This bread was made of the flour from which sample No. 241 was taken. No. 260. Graham-flour bread. The graham flour used was the lot from which sample No. 242 was taken. The results of the digestion experiments are given in the following table : — Summary of Digestion Experiments with Soft Winter Wheat ; Digestibility of Nutrients and Availibility of Energy of Bread ALONE. Experi- ment Xo Subject No. Kind of Food. Protein. Carbo- liydrates. * Energy. Experiments with Indiana Wheat. Per cent. Per cent. { Per cent. 309 1 White Bread (mixed grade flour) 94-2 95-6 ! 90-4 310 2 ,, ,, ,, ,, 89-4 90-0 1 90-4 311 1 3 83-0 95-8 ' 90-4 Average of 3 88-9 90-0 90-4 312 ! 1 Entire-wheat Bread 89-5 90-3 85-2 313 i 2 84-9 89-8 84-5 314 i 3 79-3 88-8 82-9 A\"erage of 3 84-6 89-6 84-2 Experiments with Michigan Wheat. 315 1 White Bread (standard patent) 930 97-6 93-4 310 2 94-4 98-3 951 317 3 90-9 98-2 941 Average of 3 92-8 98-0 1 94-2 318 1 Entire- wheat Bread 80-8 92-2 87-9 319 2 '9 99 82-8 93-2 86.8 .320 3 „ 87-4 93-4 89-4 I i Average of 3 85-7 92-9 ! 88-0 321 ! 1 Graham Bread . . 79-2 88-9 82-7 322 2 ,, . 80-1 89-5 81-7 323 ' 3 „ 1 79-0 89-6 83-5 Average of 3 79-4 89-3 I 82-6 These results are summarised in the following table : — No. of Sample. Grade of Flour. Protein. Carbohydrates. | Heat of Combustion per Gram. Total. Digest- ible. Total. Digest- ible. Total. Avail- able. 221 Mixed-grade Flour Per cent. 12-30 Per cent. 10-93 Per cent. 75-94 Per cent. 72-90 i Calories. 4-010 Calories. 3-645 219 Entire-wheat Flour 12-80 10-82 74-40 66-66 4-020 3-384 240 Straight White Flour . . 10-92 10-13 77-15 75-61 3-799 3-579 241 Entire- wheat Flour 12-01 10-29 74-17 68-80 3-860 3-399 242 1 Graham Flour . . . . 12-24 9-72 73-27 65-43 3-906 3-226 542 THE TECHNOLOGY OF BREAD-MAKING. With soft winter wheat flours, the results obtained are in entire accord- ance with those in tests wdth bread made from different grades of hard wheat flours. The experiments were continued with Oregon soft wdnter and Oklahoma hard wdnter wheats, of which the following are particulars : — No. 269. Oregon white winter wheat weighing 69 lbs. per bushel, grow'n at the Oregon Experiment Station, Corvallis, Oreg. No. 271. Graham flour prepared from Oregon wheat. No. 269. No. 272. Entire-wheat flour from Oregon wheat. No. 269. No. 273. Straight-grade flour from Oregon wheat. No. 269. About 70 per cent, of the Avheat was recovered as straight -grade flour. No. 270. Hard wdntei? Weissenburg wheat weighing 62 lbs. per bushel, grown at the Oklahoma Ex:periment Station, Stillwater, Okla. No. 274. Graham flour from Oklahoma wheat. No. 270. No. 275. Entire-wheat flour from Oklahoma wdieat. No. 270. 86 per cent, of the wdieat was recovered as entire- wheat flour. No. 276. Straight-grade flour from Oklahoma wheat. No. 270. About 70 per cent, of straight -grade flour was recovered. No. 413. Bran from Oklahoma wLeat, No. 270. No. 414. Germ from Oklahoma wheat. No. 270. No. 415. Bran flour. The sample was prepared by adding 14 per cent, of finely ground bran (No. 413) to the straight-grade Oklahoma flour (No. 276). No. 416. Germ flour. The sample was prepared by mixing 93 per cent, of straight-grade Oklahoma flour (No. 276) with 7 per cent, of finely ground germ (No. 414). Particulars of these are given in the following table Composition and Heat of Combustion of Wheats and Flours. 1 Sam- ple No. Kind of Material. Water. Protein. Fat. Carboliydrates when Protein is estimated a'. — Ash. Heat of Combus- tion per gram. (NX6-25). (Nx5-7).| N X 6-25 N X 5-7 Calcu- 1 lated. I Deter- mined. 269 Oregon Wheat . . Per ct. 8-99 Per ct. 9-12 Per ct. 8-32 Per ct. 1-83 Per ct. 78-30 Per ct. 79-10 Per ct. 1-76 Calories. 3-997 1 Calories. 4-008 271 1 Graham Flour from No. 269.. 8-15 8-97 ' 8-18 1-68 79-43 80-27 1-72 1 4-023 1 3-990 272 Entire-wheat Flour from No. 269 . . 8-66 8-25 1 7-52 1-67 80-35 81-03 1 1-07 4-016 ' 3-900 273 Straight-grade Flour from No. 269 . . 8-94 7-55 6-90 1-25 I 81-82 1 82-47 0-44 3-993 3-880 i 270 Oklahoma Wheat 8-65 16-82 15-33 1-83 71-33 72-87 1-32 4-160 4-110 ; 274 Graham Flour from No. 270.. 7-73 16-81 15-33 1-79 72-35 73-83 1-32 4-193 4-178 1 275 Entire-wheat Flour from No. 270 . . 7-46 16-63 15-16 1-64 73-05 74-52 1-22 4-201 1 4-159 276 Straight-gradeFlour from No. 270 . . 9-93 15-06 13-74 ' 0-92 73-57 74-89 0-52 4-065 4-040 413 Bran 9-91 16-39 14-93 ’ 4-50 62-79 64-25 6-41 4-022 4-103 414 Germ 8-73 29-88 1 27-24 11-23 45-45 48-09 4-71 4-716 4-597 415 Bran Flour 9-69 15-35 13-96 1-48 72-23 73-82 1-25 4-077 3-876 , 416 Germ Flour 9-63 16-30 14-87 1-66 71-54 ^ 72-97 0-87 4-124 3-962 , The jireceding table illustrates the fact that different wheats and different types of flour vary wddely in composition. Thus, straight-grade flour (No. 276) prepared from Oklahoma wheat contained a much larger amount of protein than graham flour (No. 271) prepared from Oregon wdieat. This empha- sises the importance, previously pointed out, of prepaiing the different kinds of flour for investigations of this nature from the same lot of wheat. Otlierwise, if a straight-grade flour milled from one lot of wheat w'ere com- pared wdth an entire-wheat flour milled from another and entirely different lot of wheat, the straight-grade flour might contain either more or less starch or protein than the graham flour, according to the character of the wheats from which they were prepared. THE NUTRITIVE VALUE OF BREAD. 543 The breads prepared from the above flours had the following com- position : — Composition of Bread used in Digestion Experiments with Oregon and Oklahoma Wheat Breads. ;Sam- ple No. Kind of Material. Water. Protein (NX 6-25) Fat. Carbo- hy- drates. Ash. Heat of Combus- tion per gram. Per cent. Per cent. Per cent.' Per cent. Per cent. Calories. Bread made from : 1 277 Oregon Entire-wheat Flour . . 39-95 5-70 1-09 52-39 0-87 2-566 294 Oregon Straight-grade Flour . . 34-95 5-41 0-89 57-85 0-90 2-765 311 Oregon Graham Flour . . 38-55 6-11 1-12 52-68 1-54 2-562 328 Oklahoma Straight-grade Flour 37-65 10-13 0-64 51-14 0-44 2-783 345 Oklahoma Entire-wheat Flour 41-31 10-60 1-04 46-11 0-94 2-714 362 Oklahoma Graham Flour 42-20 10-65 1-12 44-58 1-45 2-516 379 Straight-grade Flour with 149^ Bran . . 43-20 9-50 0-84 45-55 0-91 2-499 396 Straight-grade Flour with 7"b 1 Germ 38-00 1 11-07 1-13 49-12 0-68 2-793 Digestibility of Nutrients and Availibiltty of Energy of Bread alone. Experi- ment No. Subject No. Kind of Food. Protein. i Carbohy- drates. ! ! Energy. Per cent. Per cent. Per cent. Experiments with Oregon Wheat. 469 'l Entire- wheat Flour Bread 66-9 93-8 87-0 470 2 95 99 99 • • . 77-5 94-6 89-5 471 3 68-9 93-8 86-7 1 Average . . . . . . 71-1 94-1 87-7 472 1 Straight-grade Flour Bread 85-6 98-0 94-8 1 473 j 2 89-4 98-9 96-3 ! 474 : 3 79-8 97-8 91-0 Average 84-9 93-2 95-0 i 475 1 1 Graham Flour Bread 60-6 90-1 80-7 i 476 2 65-3 90-9 83-5 477 3 a 40-5 92-6 82-6 1 Average 63-0 91-2 82-3 1 Experiments with Oklahoma Wheat. 481 1 Entire-wheat Flour Bread 75-7 89-6 81-9 482 2 ,, 84-4 92-0 86-5 483 3 78-7 90-0 82-9 Average 79-6 90-5 83-8 478 1 Straight-grade Flour Bread 90-2 96-7 90-7 I 479 2 99 99 99 91-9 98-2 93-3 480 3 90-6 98-1 92-2 Average 90-9 97-7 92-1 484 1 Graham Flour Bread 74-1 85-6 76-1 485 2 99 99 99 82-2 89-1 86-1 486 3 - 75-6 87-4 79-6 Average . . . . . . 77-3 87-4 80-(> a Omitted from average. 544 THE TECHNOLOGY OF BREAD-MAKING. The second table on page 543 is a summary of the results of the diges- tion experiments. Examination of this shows that different subjects possess- different digestive powers for the protein of graham bread. The figure with subject No. 3 is regarded as abnormally low and therefore is not in- cluded in the average. But notwithstanding the wide range in the digesti- bility of protein of the same flour by the different subjects, the results are in perfect accord in this respect, that each subject digested the nutrients of the straight-grade flour more thoroughly than those of the entire-wheat, and the nutrients of the latter more thoroughly than those of the graham flour. Likewise the energy of the straight-grade flour was more available- than that of entire-wheat or graham. The following table summarises the relative digestibility of the different- grades of flour : — Proportion of Total and Digestible Nutrients and Total and- Available Energy in Different Grades of Oregon and Oklahoma Flour as Milled. Sample j 1 Kind of Flour. Protein (N x 6-25). Carbohydrates. Energy per gram.. Xo. ' Total. ' Digest- ible. Total. Digest- ible. Total 1 Avail- able. 271 Oregon Graham Flour . . Per ct. 8-97 ! Per ct. 5-65 Per ct. 79-48 Per ct. 72-49 Calories . Calories. 3-990 3-284 272 i Oregon Entire-wheat Flour 8-25 i 5-87 80-35 75-61 : 3-900 3-420 273 1 Oregon Straight-grade Flour . . 7-55 6-41 81-82 80-35 3-880 3-686 274 [ Oklahoma Graham Flour 16-81 12-99 72-35 63-23 4-178 3-367 275 ' Oklahoma Entire-wheat Flour 1 16-63 13-24 73-05 66-11 4-159 3-485 276 Oklahoma Straight-grade Flour 1 15-06 13-69 73-57 71-88 4-040 3-721 The general results of these latter experiments are in entire accord with those previously described. Experiments with “ Bran Flour ” — The lesser digestibility of whole- meal and graham flour is at times attributed to the coarseness of the branny particles. In order to determine what influence bran in a fine state of division would have upon the completeness of digestion, three experiments were made with straight -grade flour to which very finely ground bran was added. For convenience this material has been designated “ bran flour.'^ This bran flour was prepared from milling products of Oklahoma wheat. A quantity of the bran (No. 413) was ground until it was very fine. Some of the ground bran was then mixed with straight -grade flour (No. 276), tlie quantity of bran in the mixture (No. 415) being 14 per cent, of the total, which was about the proportion of bran removed in milling. Bread was^ made from this modified flour in the same way as with the ordinary flours, and was used in digestion experiments. A summary of the results is given in the first table on the following page. Considering the averages of the experiments with both kinds of flour, the digestibility of the bread from the flour with the bran was, for protein 85-9 per cent., and for carbohydrates 93-4 per cent., whereas that of the bread from the same flour without the bran was, for protein 90-9 per cent., and for carbohydrates 97*7 per cent. The inference from these results is that the addition of the finely ground bran decreased the digestibility of the product. Though the bran flour contained a larger percentage of protein than tho flour without the bran, in consequence of its lower digestibility the nutritive value of the former was actually less, as will be apparent from a comparison THE NUTRITIVE VALUE OF BREAD. 545 Digestibility of Nutrients and Availability of Energy of Bread FROM Straight-Grade Flour with and without Bran. Expel i- ment No. Subject No. Kind of Bread. Protein. Carbohy- drates. Energy. 487 1 Bread from Straight-grade Flour with Bran added Per cent. 83-2 Per cent, i 93-0 Per cent. 86-3 488 2 Ditto . . 84-4 92-8 86-8 489 3 Ditto . . 90-0 94-3 89-7 Average . . 85-9 j 93-4 1 87-6 478 i 1 Bread from Straight-grade Flour without Bran . . 90-2 96-7 90-7 I 479 2 Ditto . . 91-9 98-2 93-3 480 3 Ditto . . 90-6 98-1 92-2 1 Average 1 90-9 97-7 92-1 of the data summarised in the following table, showing the percentages of total and digestible nutrients and the total and available energy per gram in both kinds of flour : — Comparison of Total and Digestible Nutrients and Total and Available Energy in the same Flour with and without Bran. Sample No i Kind of Flour. Protein (N x 6-25). Carbohydrates, j Energy per gram. Total. Digest- ible. i Total. Digest- ^ . Avail- able. 415 Straight-grade Flour with Bran Per ct. Per ct. Per ct. Per ct. Calories. Calories. added . . 15-35 13-19 72-23 67-46 3-876 3-395 276 Straight-grade Flour without Bran . . 1 15-06 1 13-69 1 73-57 71-88 4-040 1 3-721 There was a larger percentage of total protein and a smaller percentage of total carbohydrates in the flour with the bran than in that without it ; but comparing the digestible nutrients it will be observed that what little v as gained in total amount added by including the finely ground bran v^as more than lost in the decreased digestibility due to the addition of the bran, the proportions of digestible nutrients and available energy being larger in the flour without the bran added. This means that from the same amounts of both kinds of flour the body would actually derive more nutrients and energy from the flour without the bran in spite of the fact that the amount of protein is larger in the flour with the bran added. Experiments with “ Germ Flour ” — Experiments similar to those with bran were also made to determine the influence of the addition of germ to Avliite flour. A sample of germ (No. 414, obtained in milling flour No. 276) containing 29-88 per cent, of protein and 11-23 per cent, fat was ground in the same manner as the bran. A mixture, designated as “ germ flour,"' was then made, containing 93 per cent, of Oklahoma straight -grade flour (No. 276) and 7 per cent, of the finely ground germ, the germ being added in about the same proportion as is removed during the milhng process. Bread was made from this mixture as previously described, and a digestion experiment was conducted with three subjects. The results of the experi- ments are summarised in the following table. For comparison the results N N 546 THE TECHNOLOGY OF BREAD-MAKING. of experiments with bread made from the same flour without the germ arc also included. Digestibility of Nutrients and Availability of Energy of Bread FROM Straight-Grade Flour with and without Germ. j Experi- ' ment No. Sub- ject No. Kind of Bread. Protein. Carbohy- drates. Energy. 1 Per cent. Per cent. Per cent. 490 I 1 Bread from Flour with Germ added i 87-6 97-0 90-5 491 2 ,, ,, ,, ,, 1 9M 97-9 92-3 492 3 91-3 97-9 91-7 t Average 90-0 97-6 91-5 478 1 Bread from Flour without Germ 90-2 96-7 90-7 479 2 J? 9? 91-9 98-2 93-3 480 3 90-6 98-1 92-2 Average j 90-9 97-7 92-1 Apparently the presence of the finely ground germ exerts no appreciable influence upon the digestibility of the flour. The relative nutritive value of the flour with and without the germ is illustrated by the data here summarised. Comparison of Total and Digestible Nutrients and Total and Available Energy in the same Flour with and without Germ. i Sample No. 1 Kind of Flour. 1 i Protein (N x 6-25) Carbohydrates. Energy per gram . Total. 1 Digest- tible. Total. Digest- ible. Total. Avail- able. 416 Straight-grade Flour with Germ Per ct. Per ct. Per ct. Per ct. Calories. Calories . added . . 16*30 14*67 71*63 69*91 3*962 3*625 276 Straight-grade Flour without Germ . . 15*06, 13*69 73*57 i»- 71*88 4*040 3*721 As will be seen, both the total protein and the digestible amount are larger with the germ than without it, the order being reversed in the case of the carbohydrates. The difference is much greater when, as in the authors’ previously described experiments, there is a much larger propor- tion of germ added. Snyder thus summarises the whole of his conclusions : — In fifty-four digestion trials with both hard spring wheats and soft winter wheats in which six separate samples of wheat have been milled so as to produce the three types of flour — graham, entire-wheat, and straight grade — uniform results have been secured, and in all of the comparative trials the largest amounts of available nutrients and energy have been secured from the white flour. In the three digestion trials in which finely pulverised bran was added to white flour in the same propor- tion as is removed in milling, it was found that the addition of the bran lowered the digestibility of the flour so that a smaller amount of digestible nutrients and available energy was obtained from the bran flour than from the white flour with which the bran was mixed. 648. Mineral Nutritive' Value. — This section of the subject has not been worked out with anything like the completeness that has been attained with tlie organic constituents of_flour. Even in whole wheat the ash is THE NUTRITIVE VALUE OF BREAD. 547 not very high, the principal constituents being phosphoric acid and potash. As stated in Chapter V., the potash and lime are proportionately more in the fine fiour than in the wheat ; so also are the silica and ferric oxide. Even in the flour, the lime is very, little amounting only to 5*59 per cent, of the total ash. Hutchison [Food and Dietetics, 1900, Chapter XVI.) discusses the mineral requirements of the body somewhat fully. He finds that the amount of mineral matters present in an ordinary mixed diet is more than sufficient for all the needs of the body, and that amount he fixes at about 20 grams per day. As to the form in which they enter into an ordinary diet, most of them are in a state of organic combination, such as calcium and phosphorus in milk. “ It would appear that such organic mineral compounds are of special value in nutrition. It cannot be maintained, however, that it is only in such forms that mineral matter can find access to the blood. Ex- periment has shown that even such a substance as carbonate of lime is absorbed to some extent.’' From analyses of human milk, it would appear that an infant requires about 0*33 gram of lime daily : the adult requires less, because of the cessation of the growth of the bones. In the case of pregnant women, the requirements of the foetus in the way of bone formation increases the demand for lime. A litre of milk, whether whole or skimmed, contains about 1 -5 grams of lime, or 0 -86 gram per pint. Hutchison regards phosphorus as a most important building material of the body, being found in cell nuclei and in abundance in bones and nerve tissue. It is therefore of great importance during the development of young animals. Phosphorus is present to a much greater extent in meats than in vegetable products ; >among the latter, haricot beans contain a very high proportion. “ The phosphorus contained in foods is for the most part present in an organic form of combination . . . but in part also in an inorganic form as phos- phates of the alkalies or earths. There is reason to believe that the organic forms are the more valuable for contributing to the growth and repair of tissue. Examples of these are the chemical substances nuclein, lecithin, •glycero -phosphoric acid, and phospho-carnic acid, all of which are probably valuable dietetic sources of the element. The foods richest in these are such articles as yolk of egg . . . and the germ of wheat. It is doubtful, on the other hand, whether the inorganic compounds containing phosphorus are of much value in the body. . . . One can, therefore, hardly approve of the addition to the diet of phosphates in their inorganic form. . . . The recommendation of such preparations is based upon the groundless assumption that an ordinary mixed diet is too poor in phosphorus to be ^ble adequately to supply our need of that substance. It may be remarked in this connection that we know of no diseased condition which can be •clearly traced to a deficiency of phosphorus in the diet. This is true, indeed, not of phosphorus alone, but of all the other mineral ingredients of the diet with the exception of iron, and possibly also of calcium. A deficiency of iron in the food may, as already remarked, lead to the development of anaemia, and too little lime in the food may cause the bones of children to become soft ; but with these rather doubtful exceptions it may be safely assumed that an ordinary diet will amj^ly provide for all the mineral matter we require.” Hutchison further remarked that “ of the comparatively small amount of mineral matter met with in bread, one-fourth is excreted uii- absorbed. Seeing that this is the case, it is surely futile to recommend the use of bread containing a larger amount of mineral constituents.” As already observed, Brunton and Tunnicliffe regard brown bread as being preferable to white where mineral ingredients and especially lime salts are deficient in other articles of food. As wheat is one of those articles in which lime is very deficient, it is difficult to see where in any case bread, 548 THE TECHNOLOGY OF BREAD-MAKING. whether brown or wliite, can very materially help as a lime food. On this point, Girard states that the difference in amount of phosphoric acid in white and brown breads is but small, and that in view of the quantity of phosphoric acid contained in ordinary food rations, this difference is insig- nificant. In any case there is a large excess of phosphoric acid in the food over the highest estimate of what is normally eliminated (viz., 3 T9 grams per day). He therefore concludes that for general consumption white bread is the best. (Comptes Rend., 1896, 122, 1382.) 649. Importance of the Mineral Constituents of Foods, Ingle. — A paper on this subject was read at the Leeds Congress of the Royal Institute of Public Health in 1909. From the analogy of milk, Ingle regards the most suitable proportions of lime and phosphoric acid (P2O5) in food as being about 0-87 of hme to 1 of phosphoric acid. In support of this view he cites the authority of Weiske, by whom it has been shown that rabbits fed on oats alone developed thin, fragile skeletons, while similar animals fed upon oats and meadow-hay produced normal bones ; moreover, that the addi- tion of sodium dihydrogen phosphate to the diet intensified the bad effect upon bone development, while the addition of calcium carbonate to a diet of oats only, greatly improved the development of bone. Now oats contain about seven times as much phosphoric acid as lime, while meadow-hay contains 2-5 times as much lime as phosphoric acid. The wTiter points- out that in seeds generally, among which wheat is included, there is this injurious excess of phosphoric acid, and although in wheat there is between three and four times as much magnesia as lime, yet for bone formation, magnesia can only to a limited extent replace lime, for in the ash of bone only about 1 per cent, of magnesium phosphate is usually found, as com- joared with from 84 to 87 per cent, of calcium phosphate. The vTiter then proceeds to express himself very strongly as to the merits, or ratlier demerits, of bran in the following terms : — “ Allusion may here be made to what the writer believes to be a widespread fallacy — the impression that bran is well adapted to promote bone formation and nutrition. Bran is rich in ash, but contains an overwhelming excess of phosphorus pentoxide over lime — in some samples the writer found the ratio to be as high as 1 : 0-055 — and, according to the views here given, should be extremely un- suited to bone nutrition. This is indeed the case, for a disease of the bones of liorses, known as ‘ millers’ horse rickets ’ or ‘ bran rachitis,’ is knovui to be produced by the excessive use of bran as food.” He regards bone dis- eases, e.g., rickets, as being probably associated with the use of a diet con- taining a preponderance of phosphoric acid over hme, and suggests as a remedy for deficiencies in mineral constituents of food their artificial addi- tion in the form of inorganic compounds. Thus in the preparation of ‘‘ liumanised ” milk from cows’ milk, he recommends the addition of finely divided calcium carbonate. Ingle regards the preponderance of phosphoric acid rather than the deficiency of lime in cows’ milk as being the cause which renders it more liable than human milk to induce malnutrition of bone in infants. The same preponderance of phosphoric acid leads him to regard wlieat, flour, and bread, as not presenting the most favourable conditions for bone development. He recognises, however, that cereal grains and their products form a large proportion of human diet without ill effects, and for adults at least the excess of phosphoric acid is not injurious. He regards this as being possibly due to different requirements in man to other animals, and also to the fact that the phosphoric acid of the ash does not all exist in the grain as such, but is largely derived from organic phosphorus combinations as lecitliin. Such phosphorus is possibly not converted into ifiiosphoric acid in the body, and would therefore not act harmfully in bona THE NUTRITIVE VALUE OF BREAD. 549 nutrition, the really important ratio being that of lime to phosphorus pent- oxide existing as acid in the food. [Jour. Royal Institute of Public Health, 1909, XVII., 736.) 650. Nutritive Value of Phosphates, Holsti. — Almost concurrently 'with Ingle, Holsti points out that experiments on animals in which the question has been investigated whether the body can obtain its phosphorus from inorganic sources, have not in the hands of various investigators yielded concordant results. In the present experiments described by him, in which organic and inorganic phosphorus were determined in the food and excre- tions of man, the result obtained is that it is possible to supply the necessary phosphorus in large measure from inorganic phosphates. (Skand. Arch. Physiol., 1909, 23, 143.) 651 Conclusions. — The balance of evidence is in favour of the view that ordinary diet contains a more than sufficient quantity of phosphorus, and therefore that the amount present in bread is of but little or no importance. Ingle goes further and regards the preponderance of phosphoric acid over lime as positively detrimental. There is considerable divergence of opinion as to the nutritive value of phosphates. Thus Hutchison looks upon them with doubt, but admits that in certain cases inorganic salts such as calcium carbonate undergo some degree of absorption. Ingle evidently agrees with Wieske that oats is a very bad bone-forming food, and similarly con- demns wheat ; they both regard the addition of calcium carbonate as a definite bone-food. Ingle rather queries whether the phosphorus of such organic compounds as lecithin is even converted into phosphoric acid in the body. If not, it evidently cannot act as a bone nutrient, for which the inorganic calcium phosphate is required. Holsti, as a result of direct experi- ment, regards inorganic phosphates as capable of supplying a large measure of the necessary phosphorus of the body. The authors suggest as a pro- bable solution of the problem that the human body requires phosphorus in two distinct forms : (1) as organic compounds for the building up of brain and nerve tissue, which contain such compounds of phosphorus in large quantity ; (2) as inorganic salts for the building up of bone tissue, which consists largely of calcium phosphate. Lecithin and such substances will naturally go to the construction of nerve tissue, and inorganic phosphates to bone-formation When either organic or inorganic compounds of phos- phorus are deficient, the human body is probably able to utilise for both purposes phosphorus compounds of either type. In the case of lime, the position is different, Brunton and Tunnicliffe, Ingle, and to a lesser degree Hutchison, regard lime-starvation as being within the bounds of possibility. Ingle adduces very strong evidence that such deficiency may be made up by the use of lime carbonate as a part of the food. Unfortunately, wheat in any of its forms contains very little lime. In particular, the use of bran as a food is strongly contra-indicated, as it may very possibly be the cause of actual injury to bone formation and nutrition. 652. Comparative' Bacteriological Purity. — Owing to causes over which the miller has no control some wheats reach him in a very dirty condition. As a remedy most complete installations of wheat-cleaning machinery form part of the equipment of every modern mill. The wheat is dry- scoured, washed most thoroughly and dried ; but it is impossible, owing largely to the crease in the grain, to thus ensure its absolute freedom from external impurity. Such impurity is naturally associated with the bran, and during the operations of milling remains in most part attached thereto. A portion is rubbed off by the more severe reductions into the lower grade 550 THE TECHNOLOGY OF BREAD-MAKING. flours, but the higher grade flours are practically free from any contamina- tion that may exist on the outer side of the bran. Among such impurities are found large numbers of bacteria, and some of these may be very objec- tionable, and in rare cases even dangerous in their natuie. In consequence, whole-meal and the darker low-grade flours are much more liable to bacterial contamination than those of the patent types. The results of these con- ditions have long been familiar to the baker, who knows that the darker flours are much more likely to produce sour bread. In the following experi- ment a first patent flour and a dark or low-grade flour from the same class of wheat were taken, and fermented and baked in precisely the same way. Loaves were baked from each after 3J hours and 9 hours’ fermentation respectively. They yielded on analysis the following amounts of acidity per cent. : — - White Bread, Dark Bread. After 3J hours .. .. .. .. 0-477 1-140 After 9 hours .. .. .. .. .. 0-491 1-300 The less fermented loaves had the following characteristics : White, sweet in smell and taste ; Dark, characteristic odour of bread from low- grade flours, but perfectly sweet in taste and smell. The 9-hour loaves had shown some further change. The White was darker in colour, had an incipient sour smell, but no sour taste. The Dark had the colour changed to dark reddish brown, sour smell, and unpleasant taste, rather of decomposi- tion than acidity. Kenwood, in conjunction with one of the authors, has on several occa- sions made comparative bacteriological examinations of wheat and flours. The following are the results of one such test. Three flours were taken : — A. Highest grade patent flour. B. Lower grade flour. C. Stone-milled flour. These were similarly treated, and preparations of each were incubated for bacteria on gelatin plates. At the end of 42 hours the following observations were made : — A. No growth. B. Four large colonies and over 100 small ones (non-liquefying). C. Twenty well-marked colonies, and many organisms (which could not be enumerated), had liquefled one-third of the gelatin. At the end of 72 hours : — A. One non-liquefying colony. B. One liquefying colony, and quite 200 small non-liquefying ones. C. The gelatin was entirely liquefied. In another test, experiments were made with a wheat containing B. coli communis. The wheat itself yielded twelve colonies of coli. Samples of liighest grade flour, medium grade flour, and bran from this wheat were examined. Repeated tests on the highest grade flour gave no growths of coli. In each of separate tests, two colonies of coli were obtained from the medium grade flour. The bran yielded a growth of coli which covered the gelatin plate. High grade flours are practically sterile, and bacteriologically cleaner than medium and low-grade flours, and far cleaner than whole-meals. Such organisms as B. coli communis, if present in the wheat, are absent from the liighest grade flour, present in small quantity on that of medium grade, and abundant in whole-meal. The same differentiation would no doubt apply to other organisms having the same habitat as B. coli communis, if they happened to be present. THE NUTRITIVE VALUE OF BREAD. 551 653. Attractiveness and Palatability. — These two factors have immense weight in deciding what shall be the leading type ot bread consumed by the community. They are also of the utmost importance. As long ago as 1857, Lawes and Gilbert recognised that : “ It is also well-known that the poorer classes almost invariably prefer the whiter bread, and among some of those who work the hardest and who consequently soonest appre- ciate a difference in nutritive quality (navvies, for example) it is distinctly stated that their preference for the whiter bread is founded on the fact that the browner passes through them too rapidly ; consequently, before their systems have extracted from it as much nutritions matter as it ought to yield them.'' The fact of this preference also applies to such districts as some parts of Scotland, where very little meat is eaten, and also to even the poorest parts of Ireland. In both cases a very white bread is demanded. But not only does this taste exist among the poorer and harder physically worked classes, it is also general throughout the whole community. As recently stated in the daily press, “ there is a popular craving for white bread." If asked the reason why they preferred a white loaf, the probable answer of the people would be We prefer a white loaf because it is more dainty in appearance, and because whiteness is instinctively associated with cleanliness. A muddy-looking loaf may be quite clean, but does not so thoroughly convey that impression as a creamy white one. Further, the white loaf has a nicer taste." Snyder puts it on record that during the severe monotony of his digestion tests, in which the subjects were restricted to a diet of bread and milk only, they keenly preferred the white bread to the browm. In other words, the general taste regards the white loaf as the more attractive and palatable. Authorities on diet regard both of these as being of importance. Tunnicliffe writes : “ Recent research has distinctly taught us that, from the point of view of its nutritive value, great importance attaches to the appetising appearance of food." [Blue Book on the Use of Preservatives in Food, p. xxxi.). Hutchison is also strongly in favour of regarding the flavour of food as one of the essential characteristics of the diet. He sums up his position by the remark : “To persons of jaded appetite, however, and to invahds and convalescents, the flavouring agents of the food are very powerful aids to digestion, and no adjustment of the diet in such cases can be regarded as satisfactory which leaves this consideration out of account." {Food and Dietetics, p. 274.) On general dietary principles, therefore, there is a scientific justification for the popular preference. 654. Complementary Foods to Bread. — In view of the fact that bread is naturally deficient in protein and fat, amongst organic nutrients, and in lime among mineral matters, it may be well to indicate those articles of food which are appropriately regarded as complementary or supplementary to bread itself. Bread is very rarely eaten alone ; meat and cheese supply its deficiency in protein ; leguminous vegetables such as haricot beans have the same effect. Fat is almost universally added to bread in the form of butter. Dietetically, jam or other sweets cannot be regarded as an efficient substitute for butter, margarine, or dripping. In view of the deficiency in lime, milk is strongly indicated as an accompaniment to bread. Here custom anticipates science by causing bread- and- milk to occupy a prominent position in the dietary of children. May not the reputation of “ the halesome parritch " as a bone-food be largely due to the milk consumed therewith rather than to the oats from which it is prepared?' In improved methods of bread-making, both fat and milk are at times employed. Both are good ; but the latter especially, whether with or without the cream, serves to increase the lime content of the bread. If 552 THE TECHNOLOGY OF BREAD-MAKING. bread be made entirely with skimmed milk, a half kilo (approximately 1 lb.) will contain about 0-3 gram of lime, or roughly the daily amount re- quired by an infant. Such bread would be far better adapted to the require- ments of pregnant women than that from whole-meal. Judging by analogy, the addition of a small proportion of an appropriate lime salt would be a further advantage. Such salt might possibly be the carbonate, which would be changed into the chloride by the hydrochloric acid of the gastric juice ; or it might be added direct as the chloride, in which case it would partly replace sodium chloride or common salt. In some districts a portion of the liquor used in making dough consists of lime-water ; the lime of this is converted into the carbonate, by the carbon-dioxide gas evolved during fermentation. The use of hard waters for bread-making, t.e., those containing calcium carbonate or sulphate, also adds to the lime content of the bread. Hard water is itself an important source of lime in the daily income of food, and may under certain circum- stances contribute that substance in excess. 655. Summary. — The foregoing data justify the following conclusions. Taking breads as supplied by the baker, white bread is more nutritious than whole-meal or ordinary brown breads. The average best white bread is more nutritious than the second quality or that made from the darker or low-grade flours. When from any kind of wheat, standard patent (which is practically the whole of the flour of the wheat) is compared with entire- wheat, and graham flour from the same wheat, the white flour yields more nutriment and energy than either of the others. The addition of finely divided bran to white flour lowers the nutritive value of the mixture. The addition of germ in excess of that normally present in wheat, in- creases the nutritive value of the bread. Wheat and all kinds of flour therefrom are comparatively poor in mineral constituents. The phosphoric acid is largely in excess of the lime. No diseased condition is known, which can be clearly traced to a deficiency of phosphorus in the diet. All breads contain more phosphates than are absorbed by the human digestive system. All wheat preparations are deficient in lime. Bran is detrimental to healthy bone-formation. The human body requires phosphorus in two distinct forms, as organic compounds for the building up of brain and other phosphoric tissues, and as inorganic salts for the building up of bone tissue which consists largely of calcium phosphate. In case of deficiency of compounds of either type, the body is probably able to utilise for both purposes phosphorus compounds of either variety. Wheat is liable to bacteriological contamination, which conceivably may be of objectionable or even dangerous character. The whole-meal wili obviously contain the same bacteria as the wheat. The low-grade flours contain less bacteria than the wheat, but some are still present. The high-grade or patent flour is practically bacteriologically clean, even when made from a eontaminated wheat. The bakers’ best white bread -is more attractive and palatable than darker coloured or whole-meal breads made from plain flour or meal only. These in themselves are valuable nutritive assets. The nutritive deficiencies of bread are best remedied by the addition of butter, milk, cheese, meat, and leguminous vegetables to the diet. These suj)ply respectively fat, lime salts, and protein. Hard water, or appropriate lime salts added direct, would probably help in correcting the deficiency of lime in wheat. THE NUTRITIVE VALUE OF BREAD. 553 No case has been made out for recommending the use of Avhole-meal Bread by growing children or i:>regnant or nursing women. 656. “ Standard Bread.” — Since the foregoing was written there has been a revival of the controversy as to the respective merits of various types of bread. An important contribution to the discussion consisted of a manifesto signed by eight eminent London medical men, of which the following is a copy : — “ We, the undersigned, believe it to be a national necessity that a stan- dard should be fixed for the nutritive value of what is sold as bread. Such a standard has already been enforced by law for milk. The standardisation of bread is even more important, bread and flour forming about two -fifths of the weight of the food consumed by the working classes and constituting almost the whole diet of many poor children. “ In view of the inf erior nourishing qualities of the white bread commonly sold in this country, we urge that legislation should be passed making it compulsory that all bread sold as such should, unless distinctly labelled otherwise, be made from unadulterated wheat flour containing at least 80 per cent, of the whole wheat, including the germ and semolina.” It is to be feared that the fixing of a standard for the nutritive value of bread is not so simple as would appear on the face of the above document. Taking two such typical wheats as English and Manitoban of the 1910 crop, both largely used by British millers, their protein contents were 9-2 and 14-3 per cent, respectively. If both were turned into standard flour, the Mani- toban would in protein value be more than half as rich again as the English. These extremes are as a matter of fact much wider than are met with in practice in commercial wheat flours. In other words, the so-called standard permits a greater variation in nutritive value than is found without its adoption in the white bread flours of ordinary bakers. In practice, the miller aims at getting as long a straight-run flour as he can out of every variety of wheat. By straight -run is meant the whole of the flour the wheat is capable of yielding in a condition of freedom from particles of the branny envelope or germ. The percentage of such straight- run flour varies considerably in different wheats. In the dictionary of wheats, pages 284-289, the extreme figures given are 60 and 74 per cent, respectively. In exceptional wheats the yield may be as low as 55 per cent, or as high as 75 per cent, of perfectly good flour. This straight-run flour is the normal product of every mill, and has always been obtainable commercially without the least difflculty. In practice some of the straight- run is divided into a whiter flour known as “ patents,” and a darker flour called households or “ seconds.” By whatever names they may be Imown the millers’ leading grades are : — 1. Best quality, consisting of “ patents ” or whitest portions of straight- run. 2. Second quality, consisting of straight-run. 3. Third quality, consisting of the remainder of the straight-run after the removal of the patents. Obviously, intermediate flours may be prepared by mixing these three varieties in different quantities or altering the proportions of patents and remainders into which the straight-run is separated. But the main thing is that the straight-run is the starting point ; the variations therefrom are simply further separations made to meet the requirements of purchasers. The millers’ straight-run is the whole of the flour of the wheat and no more than the flour, and varies in percentage with the actual flour content of the wheat itself. The suggested standard is “ at least 80 per cent, of the whole wheat,” and takes no cognisance of the amount of flour the wheat really 554 THE TECHNOLOGY OF BREAD-MAKING. possesses. Thus a standard flour made from Azima or Ghirka wheat would contain about 75 per cent, straight-run flour, and 25 per cent, of germ and branny matter. If the standard flour be milled from Minnesota or Mani- toba wheats, it will contain 92-5 per cent, of straight-run flour and 7*5 per cent, of germ and branny matter. Which of these is the more desirable quantity ? Or if 7*5 per cent, of offal is sufficient for a standard with Manitoba wheats, why insist on 25 per cent, in the standard flour from Azima ? If a certain proportion of branny matter is desirable in all flours, then surely in a proposed standard having legal sanction, the proper and most desirable amount should be fixed a little more precisely. In the next place the standard flour must include the germ. In old stone-milling times the germ was always more or less comminuted by the millstone, and so some portion got into the flour ; but even in those days the main part was dressed out with the offal. Still the portion which found its way into the flour was sufficient to materially injure the quality. The most essential functions of the germ in the economy of the growing wheat plant are to effect the decomposition of both the starch and protein contents of the endosperm. In the resting seed the germ is separated from the endosperm by the scutellum or shield, and thus is inactive until subjected to those conditions of warmth and moisture which induce ger- mination. But if ground up into the flour its enzymes are set free, and may at once in the presence of sufficient warmth and moisture commence the attack on the endosperm. It is a matter of common knowledge among millers that in fact objectionable changes do take place in flour containing germ from the very time of manufacture. Further, when such flour is sub- jected to fermentation, excessive diastatic action is likely to occur, and hence a sticky dough is liable to be produced, which yields comparatively heavy small loaves. It is because of such reasons that millers incurred the expense of efficient germ-removing plant, and sold their separated germ as offal, rather than put it in their flour and sell it as flour. If the buying^ public is willing to condone the faults of the germ, the miller will be only too pleased to return it to the flour sack. Reference may here be appro- priately made to the nature of the inner layers of the bran, which form a large proportion of the additional matter proposed to be incorporated in the 80 per cent, flour. Like the germ, these are rich in enzymes, and to- gether with it are potent agents of change in the dough during fermentation. The both will favour the production of acidity in bread ; and in summer time standard dough and bread will afford a peculiarly suitable environ- ment for the development of ropiness in the presence of the rope organism. Where standard bread is being made, a keen look-out should therefore be kept for the first signs of the advent of this trouble. (See paragraphs. 583, 584, 587.) As a set-off against the before-recited bad qualities of the germ, it has naturally a very high nutritive value ; but the quantity present in wheat amounts only to from 1-5 to 2-0 per cent, of the entire grain. Taking a 78 per cent, flour without the germ, and adding thereto one thirty-ninth its weight of germ, the quantity of fat would theoretically be increased by about 0-3 per cent., say from 1-2 to 1-5. The percentage of protein would similarly be increased about 0-55, or say from II *6 to I2T5 per cent. In tile next place tlie standard flour must contain the semolina. Semo- lina is a millers’ term for the small granular fragments into which the endosperm of a grain of wheat is broken during the process of its gradual reduction. In milling operations these are all at last ground into flour and find tlieir way into the straight-run flour. When such straight-run i& separated into a first and third quality, some streams of semolina are used for the manufacture of the higher quality and some for the lower, so that THE NUTRITIVE VALUE OF BREAD. 555 neither of the two fractions contains all the semolina. The intention is probably to insist that the standard flour shall contain all the straight-run flour and sufficient other matter to bring the percentage up to 80 of that of the wheat. One of the last but not the least of the points remaining to be dealt with in the manifesto is the allegation that the white bread commonly sold in this country is of inferior nourishing qualities. This merits some rather more detailed examination, and accordingly the authors asked a responsible firm of millers to specially mill for them, under the firm’s personal super- vision, a series of flours. For several reasons, English wheat was selected for the purpose ; first because it is naturally a sweet flavoured wheat, and secondly because it has been widely advocated for the manufacture of standard flour. The following samples were prepared : — I. Straight-run roller-milled flour, amounting to 70 per cent, of the wheat. II. Stone-ground flour from the same wheat, with 20 per cent, of the coarser bran removed, leaving 80 per cent, of the wheat to form standard flour. III. Patent flour consisting of 30 per cent, of the straight-run. IV. Bakers’ flour consisting of the remaining 70 per cent, of the straight- run. Being asked to quote the commercial price of these flours, the millers replied : “Of course such flours as these would not be used hy bakers. They demand a blend of 70-80 per cent, foreign. The prices are as under, net delivered : stone-ground, 21s. ; patent, 29,9. ; and bakers’, 2Qs. per sack.” In view of the millers’ strong expression of opinion, a further sample of flour was prepared by the authors, in order to imitate more closely the actual mixture, containing English wheat, which would be prepared for the baker and sold by him as bread to the public. This had the following composition : — V. Mixture of 50 per cent, straight-run flour. No. I., with 50 per cent, strong American patent flour. The whole of these were subjected to analysis with the folio vdng results: — ■ Analyses of Flours. Constituents. I. S.R. II. Std. III. Ptnt. IV. Bkrs. V. i Am. Moisture . . . . . . , 14 82 14-12 14-60 1500 13-20 Proteins 10 09 11-05 9-97 10 21 11-90 Carbohydrates. . . . . . i 73-37 7271 7421 7306 73-24 Fat 1-10 1-38 0-84 1-17 1-16 Phosphoric Acid 0 26 0-35 0-18 0-27 0-27 Other Mineral Matter 0-36 0-39 0-20 0-29 1 0 23 Total Dried Solids 100-00 85-18 100-00 85-88 100-00 85-40 100-00 85-00 100-00 86-80 Proteins, per cent, of Dried Solids 11-82 12-86 11-67 1201 13-71 Total Ash 0-62 0-74 0-38 0-56 0 50 Energy in Calories . . . . 1 3524 356 2 352-9 352 3 359-8 i All the flours were baked into bread in the ordinary manner, flour, yeast, salt, and water only being used in their manufacture. Moisture was deter- mined on the bread, which was then subjected to an artificial digestion 556 THE TECHNOLOGY OF BREAD-MAKING. test with the object of ascertaining the relative protein digestibility of the various loaves The following quantities were taken : Bread 50 grams, water 60 c.c. decinormal hydrochloric acid 75 c.c., in which 0-3 gram of Armour’s standard pepsin had been dissolved ; this was allowed to digest for IJ hours. Fifteen c.c. of normal sodium carbonate, in which 0-5 gram of Armour’s standard pancreatin had been dissolved, was next added and digestion allowed to proceed for a further 1 J hours. The tests on the whole of the breads were carried out simultaneously, the flasks containing the mixtures being submerged in a Avater-bath at slightly above body tempera- ture, and shaken at frequent intervals. At the close of the time, an addi- tional 100 c.c. of water was added to each, which was shaken and Altered. Proteins were determined by the Kjeldahl test in the filtrates, and the following figures obtained. A deduction has been made for the protein matters of the digestive agents and the yeast employed for fermentation. Constituents. ' 1 I. SR. i II. Std. III. Pint. lA^ Bkrs. V. \ Am. Moisture 43-52 44-12 43-78 43-46 44-28 Dried Solids . . 56-48 55-88 56-22 56-54 55-72 Digested Proteins, per cent, of Bread Digested Proteins, per cent, of Dried 6-31 6-09 6-42 6-23 72-8 Solids Digested Proteins, per cent, of Total 11-17 10-89 11-43 11-02 13-06 Proteins present . . 94 50 84-68 97-90 91-75 95-25 Looking first at the results of flour analyses and comparing the straight- run, No. I., and standard, No. II., flours, the latter is considerably richer in protein ; but on turning to the results of digestion experiments, the 100 parts of straight-run bread yield 6*31 parts of digested protein, whereas the standard yields only 6-09 parts. It follows that as a source of available protein, 70 per cent, straight-run flour makes a more nutritious bread than does the proposed 80 per cent, standard. Under the conditions of the experiment, with straight-run flour, 94-5 per cent, of the total protein present is digested ; whereas of that of standard bread, only 84-68 per cent, is digested. In view of the oft-repeated assertion that millers’ white flours and bakers’ white breads are practically only starch, it is of interest to compare the patents, straight-run and bakers’ flours from the same wheat. With a 70 per cent, straight-run the proteins amount to 10-09 ; with a high class patent of the most delicate and creamy Avhite tint, the protein is 9-97 per cent. ; while the corresponding bakers’ grade contains 10-21 per cent, of proteins. Substantially, therefore, the whole three grades are alike in protein composition. But on turning to the digestion tests, the absolute amount of digested protein is higher for the patent flour bread, 6-42 per cent., than for either of the others. This is due to its very great digestibility, as 97-9 per cent, of the total proteins have been digested as against 84-68 per cent, in the case of the standard bread. So far from the white bread being of inferior nourishing qualities, the patent flour yields more protein nourishment than the standard flour from the same wheat. But as already remarked, the baker would regard all these English flours as too Aveak for his j)urpose, and insists on a liberal admixture of flour from foreign Avheats. Number V., AA'hich is composed of half English straight-run and half strong American patent, is much nearer what a baker Avould actu- ally use in practice. This flour, though a very Avhite flour, contains con- siderably more protein than the standard, 11-90 against 11-05 per cent. THE NUTRITIVE VALUE OF BREAD. 557 But when subjected to a digestion test, the amount of protein digested is 7*28 against 6-09 per cent, with the standard bread. The difference is partly due to the larger amount of protein present, and partly to its greater digestibility, 95-25 per cent, of the total being digested as against 84-68 per cent. The question may very fairly be raised as to how these artificial digestion tests compare vith the normal process of human digestion. Hutchison regards Rubner’s experiments on this point as being most conclusive. Rub- ner finds on tests with human subjects that with the finest white flour some 20 per cent, of the proteins are lost in digestion, with larger amounts in darker flours and whole-meal. In the authors’ experiments the digestion was carried considerably farther than this, as with the patent flour tests a loss of only 2-1 per cent, was experienced. These experiments were therefore too effective when compared with human digestion. But as a consequence of over-digestion there is a general levelling-up of the less digestible substances ; and therefore in the comparative tests recorded, the more difficultly digestible breads show up more favourably than they would do in experiments on the human subject. A number of other similar tests have been made wdth straight-run flours and 80 per cent, standard flours from other wheats and wheat mixtures; but in every case the comparative results both in nutritive value and digesti- bility have been the same. In one case tests were made on the breads, not only when new, but also when one day old. Both breads were less digestible on the second day, and gave 83-6 per cent, of digested proteins with the straight-run, and 78-9 per cent, with the standard bread. This is borne out in a remarkable manner by the fact that standard bread, in common with whole-meal breads, is commercially unsaleable when one day old. No direct estimations of carbohydrate digestion were made on these breads, because in all cases of flours, as excluding whole-meal, the carbo- hydrates are almost completely absorbed. But according to Rubner, what difference there is is in favour of the patent flour. In the case of fats, Rubner states that with patent flour 44-7 per cent, is lost in human digestion, and as much as 62-8 in seconds flour. There being so little fat in either of the two flours, the difference is very small, and both flours may be regarded as yielding practically the same amount of digestible fat nutriment. Taking proteins, carbohydrates and fat as a whole, the straight-run flour is of higher nutritive value in digestible materials than is the proposed standard. In the matter of mineral constituents, the straight-run flour contained 0-26 per cent, of phosphoric acid as against 0-35 per cent, in standard flour. No determinations of either iron or lime were made on either of these flours ; but another pair of similar flours, in each case from the same wheat, gave the following results : — straight-run Standard Flour. Flour. Iron Oxide, per cent. . . . . . . 0-002 0-004 L ine, per cent. .. .. .. .. 0-026 0-040 Again citing Rubner, the loss of mineral matter in human digestion amounts to 19-3 per cent, in the case of patent, and 30-3 per cent, in the case of seconds flour. In view of the fact that both these flours are finely ground, the authors are of opinion that in an acid medium such as gastric juice, most if not all of the phosphates of iron and calcium are rendered soluble. Such at least was the case in the artificial digestion tests made by them on the flours just referred to. They therefore regard all such salts in both 558 THE TECHNOLOGY OF BREAD-MAKING. instances as being available for assimilation by the human body should it require it. In paragraph 648, the question of mineral nutritive value of bread has been already fully discussed : it is there pointed out on the authority of Hutchison that no diseased condition can be clearly traced to a deficiency of any of the mineral ingredients of the diet, with the exception of iron, and possibly also of calcium. The question of the comparative food value of organic and inorganic mineral compounds is also there dis- cussed. In the case of lime, the total quantity from the food standpoint is negligible in both varieties of bread. The difference between the two is 0-014 per cent, in favour of the standard flour. It may be instructive to see what these quantities actually mean. Assuming 1 lb. of bread per day to be the food ration of a man, then the lb. of straight-run bread gives him from the flour 1-19 grains of lime, while the standard bread will give him 1-68 grains of lime, or a difference of 0-49 grain in favour of the latter. Taking a medium hard water containing 30 grains of lime salts per gallon, the amount of 0-49 grain of lime would be yielded by about 5 oz. or half a tumbler of such water. There is another aspect of the case which deserves examination. Hop- kins of Cambridge has made the following public statement : — “ From my own experiments on young rapidly developing animals I am convinced that if one group of children could be kept for a fortnight on a dietary two -thirds of which was made up of 80 per cent, standard bread, and a second similar group was kept on the same food proportion of the superfine white bread, the first group would show unmistakable and most conclusive signs of the better tissue-building qualities of the standard bread. The actual amounts of pure proteins, starches, fats, sugars, and salts in a food are not, when considered alone, a sufficient criterion of the amount of building material a person can assimilate from it ; so the fact that the 80 per cent, flour retains more of the natural food elements of the grain does not prove that the body can make efficient use of them all. I do not, however, refer to the question of mere digestibility. The superior value of the 80 per cent, flour, in my opinion, lies in the fact that in such flour there are retained certain at present unrecognised food sub- stances, perhaps in very minute quantities, whose presence allows our systems to make full use of the tissue- building elements of the grain. These substances of undetermined nature are apparently removed to a great extent from the fine white flour in the milling. Curiously enough, I began long ago a series of experiments on the relative tissue building values of fine white flour and of flours which, like the 80 per cent, flour, contain a larger proportion of the whole grain. These experiments were made, among others, in the endeavour to discover the nature of the unknown substances which I have just mentioned. In their existence I believe greatly, because of my experimental results. Unfortunately I am not vSufflciently advanced to publish any concrete conclusions, but I may say that all my work to date confirms my belief in the superior food value of what is termed standard bread. After definitely proving that young animals grow' with very much greater rapidity on browm flour than on white flour, I have been able to improve the tissue-building rate of the white flour subjects by adding to their w'hite flour an extract made from the brow n flour. This suggests not so much that the 80 per cent, flour contains more ])roteins, iron, phosphorus, etc., used in building up tissues, but that it con- tains more of certain as yet little studied substances which allow us to make better use of the various ingredients of the wheat berry. To make the best use of any food material, such as proteins, etc., certain other food substances, and possibly a variety of tliem, must also be present in definite proportions. If one essential food constituent which ought to make up. THE NUTRITIVE VALUE OE BREAD. 559 say, even as little as 1 per cent, of the total food is present in only half its nor- mal amount, then when it is a case of building up the tissues the system will only be able to make use of half of the other food elements, even if these other elements make up the main bulk of the food. . . . Returning to our bread, the substances of unknown nature which I just now mentioned may need to be present in very small amounts, but if the necessary minimum is not available the utilisation, in tissue growth or repair, of all other constitu- ents is infallibly deficient. In the process of converting the wheat grain to the fine wLite flour these unknown elements apparently are lost or de- stroyed to a great extent. It follows that no matter how much iron, plios- phorus, protein, etc., may be retained in the white flour, our systems cannot make the best use of them. Probably because it is much less tampered with or disturbed in the milling, the 80 per cent, flour retains the various food elements of the grain in a much more natural combination. This alone is sufficient to account for the greater use our systems can make of the build- ing materials retained in the standard flour.'’ According to this view, the white bread may contain more digestible protein, fat, and carbohydrates than the standard bread, and yet the latter may be the more valuable article of food. The theory is advanced that standard flour contains certain at present unrecognised food substances, per- haps in very minute quantities, which may confer superior food value on the standard bread. Because these substances of unknown nature are appar- ently lost or destroyed in the manufacture of white flour, and are probably less tampered with in milling 80 per cent, flour, Hopkins regards the latter as a much more natural combination. Underlying all such hypotheses, there seems to be the belief that the wheat grain is specially designed by nature as a food for man. One readily understands that milk is thus intended for food and only for food, and that by removing any one part, which removal may be considered harmless, the whole balance of nutritive value may be upset, because some unknowm but nevertheless most important constitu- ent has been taken away, which Nature introduced for a special purpose. But the natural function of the wheat grain is the reproduction of the plant. The germ is the future plant, the endosperm is intended as its food during the earlier stages of germination, and the bran is simply the protective coating. From the point of view of plant life the endosperm or white flour portion is the only part that is intended for food. Both the germ and the inner surface of the bran contain active enzymes whose function it is to exercise a digestive action on the endosperm for the benefit of the young and growing embryo. It is now universally conceded that the whole grain is not so well adapted for human food as certain portions thereof. But once admit the principle of selection, and it is difficult to see why it is less natural to select those portions of the grain which constitute a 70 per cent, white flour, than those which yield an 80 per cent, standard flour, especially when the former contains a higher proportion of the hitherto recognised food constituents in the digestible form. Hopkins has so far been unable to discover the nature of these unknown substances, and unfortunately cannot publish any concrete conclusions. His general opinion is based on feeding experiments with young animals which grow with much greater rapidity on brown flour than on white flour. It is sub- mitted by the authors that the similarity between the digestive systems of young animals and children is not sufficiently great to enable any very positive conclusions to be drawn in the one case from observations made in the other. There are most valuable animal food-stuffs that would be absolutely unfitted for the diet of children. With regard to the proposed fortnight's experimental dietary on children, the author's opportunities of observation have been comparatively limited. But so far as they go, they 5G0 THE TECHNOLOGY OF BREAD-MAKING. have not been confirmatory of the opinion advanced. In such cases, the children have bitterly complained of the less palatable nature of their- bread, have eaten less of it, and have begged to be allowed again to have white bread. On the change being made, their bread was eaten with keener relish and more of it, with an improvement in the children's general spirits. In any reasonable children's dietary the authors have the gravest doubts as to the superiority of standard bread such as No. II. in the pre- ceding table with its 6-09 per cent, of digestible protein as against the baker's white bread No. V. with its 7*28 per cent, of protein in its digestible form. Turning from children to grown men, they express in no uncertain tone their preference for white bread. From the navvies referred to by Lawes and Gilbert, paragraph 653, to the colliers of Durham and men of the navy of the present day, these disciples of hard work all find white bread a better and more sustaining food than the browner varieties. But assuming for the moment that Hopkins has established his case, that he has identified his unknown food substances, and demonstrated their high nutritive value, there yet remains “ a more excellent way " to obtain these advantages than by the use of standard flour. In the experiments before cited, a straight-run flour of 70 per cent, has been taken, and this with another 10 per cent, of the wheat composed of the germ and finest offal makes up the standard flour. If the straight-run flour is split up into patents and bakers' grade, then the latter only may be mixed with the same 10 per cent, of germ and offal, and a flour almost identical with the standard is produced. For convenience in description, the resultant flour may be called “ Improved Standard," and is slightly the darker, because of the with- drawal of the patent flour ; in addition, the 10 per cent, of germ and offal w'hich constitute 12-5 per cent, of the whole standard flour will be a larger percentage of the improved flour. This allocation of the flour in milling w ill permit the individual who believes in the superiority of white flour to still satisfy his requirements, while the advocate of the darker flour wall also have his tastes gratified. Whatever unknown food substances are contained in this last 10 per cent, of germ and offal run into the flour, they will be present wuth all their advantages and in a more concentrated form in the improved standard flour prepared in this manner. This improved flour has another great recommendation, and that is that it can be produced and sold at 2s. 6d. per sack less at present prices than the 80 per cent, standard. In the case of the extremely poor, this greater cheapness is a very material advantage. The authors have made analyses of 70 per cent, straight-run, 80 per cent, standard, and improved standard, all obtained from the same wiieat. The following are the results straight- run. 80 per cent. Standard. Improved Standard. Proteins 10-72 11-50 12-64 Carbohydrates 75-02 74-13 72-78 Fat . . 1-06 1-46 1-75 Pliosphoric Acid . . 0-21 0-31 0-39 In the important constituents proteins, fat, and phosphoric acid, the' improved standard is about as much better than the 80 per cent, standard as that in turn is better than the straight-run. On making these into bread, the 80 per cent, standard and improved standard were scarcely distinguish- able in appearance, they were nearly exactly alike. On being subjected to the practical test of the breakfast table, the breads on comparison could not be distinguished from each other, and no preference was expressed for the flavour of either variety. Digestion tests of the same kind as before were made with these breads, in which the following results w^ere obtained : — - THE NUTRITIVE VALUE OE BREAD. 561 Straight- 80 per cent. Improved run. Standard. Standard. Digested Proteins per cent, of bread 6-58 6-37 6-86 Digested Proteins per cent, of Total Proteins present.. .. .. 95-2 93*5 91-1 The degree of digestibility diminished steadily under the conditions of the tests as the white flour was departed from, being 95-2 in the white, 93*5 in the 80 per cent, standard, and 91 T per cent, of the total protein present in the improved standard. In the case of the latter, however, the greater quantity of protein present rather more than compensates for its diminished digestibility, and a larger total was afforded by this flour. So far as the unknown substances of possibly high nutritive value, which may be contained in the added offal, are concerned, they must obviously be just as available in the improved standard as in the 80 per cent, standard, the only difference being that the quantity is proportionately greater. 657. Standard Bread, Snyder. — The authors forwarded the Standard Bread Manifesto, together with copies of the press arguments in favour of same, to Snyder, whose classic investigations of the digestibility and nutri- tive value of bread by human subjects have been so extensively quoted from in paragraph 647. They have received the following expression of opinion in reply : — “I have read with interest your letter of recent date on the subject of Standard Bread. To make Standard Bread requires standard flour, and this in turn necessitates standard wheat. Unfortunately nature does not make such a wheat — she produces wheat with proteins ranging from 8 to 16 per cent, or more. Now it is quite evident that a so-called standard loaf from a flour of low protein would have less of this nutrient than a high patent milled from wheat rich in protein. There is no definite basis upon which a standard can rest — that is a standard as the term is used in science. To make a so-called 80 per cent, flour would necessitate including in the flour a portion of the wheat offals ; and the principle has been well estab- lished that any addition of any such materials results in a decrease in the digestibility of the product as a whole. I am using the term “ 80 per cent, flour ” not in its ordinary sense, but as it is used in the article sent me — all of the flour of the wheat kernel, and 5 to 10 per cent, of wheat oflal finely ground and admixed with the flour. I think there is much misconception as to the amount of germ in wheat ; it constitutes about 7 per cent, of the ofjals and not of the entire herry, making only about 1 -7 per cent, of the entire constituents of wheat. If it is desired to secure flours with more protein, this is possible by the more liberal use of the clears which contain even more than the proposed standard. The result of any considerable amount of clears on the quality of the bread product is well-known — an inferior loaf . Hence the “ standard flour ” con- taining not only clear stock but offal also would necessarily still further lower the quality of the bread. I am satisfied that it is not feasible from a milling point of view to include in the flour the offal or any part, no matter how finely ground ; that it results in a poorer quality of bread physically, and lowers the total digestibility of the bread. I cannot see where there is anything gained by the addition of any of the wheat offals to flour ; the flour and the offal should be kept distinct. The germ, although comparatively rich in protein, is very fermentable in char- acter, and it imparts to flour an antagonistic action to yeast. It is difficult to get the pure germ without admixture with other offal. The whole art of milhnghashadfor its object the elimination of offal, and this has been strictly in accordance with scientific principles, and has resulted in the production of flour from which better bread can be made and also bread of higher nutritive value."’ [Personal February, 1911.) o o CHAPTER XXII. THE WEIGHING OF BREAD. 658. The Baker’s Position. — The baker’s attitude toward the weighing of bread is partly governed by the exigencies of its manufacture, and partly by the various sanctions imposed upon him by law. There are, moreover, scientific reasons which bear on the whole question. The authors there- fore feel justified in acceding to a somewhat general request to include this subject in the present work. The obligation to weigh bread has been imposed by law, and therefore the most convenient way of dealing with it will be to follow the chronological development of the laws relating to the weight of bread. A great deal of the substance of this chapter has already appeared in a series of articles contributed by one of the authors to The British Baker. 659. Act of 31 George II., c. 29, 1757. — The investigation of the Bread Laws requires some starting point to be taken, and for that purpose the Act now referred to may be selected. The title of the Act is “ An Act for the due making of Bread ; and to regulate the Price and Assize thereof ; and to punish Persons who shall adulterate Meal, Flour or Bread.” This is not, however, the earliest recorded Bread legislation, for the opening sentence of the Act is “ WHEREAS by an Act of Parliament made in the one and fiftieth year of the Reign of King Henry the Third, entitled Assisa Panis (&; Cervisiae, Provision was made among other Things, for setting the Assize of Bread.” This Act was variously amended, but the principle of an Assize was continued down through a series of Acts until this Public Act of the thirty -first year of the reign of George II., which was largely a consolidating Act passed in order “ to reduce into one Act the several Laws now in Force relating to the due making, and to the Price and Assize of Bread.” 660. Assize of Bread. — Whatever the original meaning of the word ‘‘ Assize ” it had come at the time of this Act to signify in this relationship an ordinance determining from the price per bushel of wheat the weight at which loaves to be sold at certain fixed prices were to be made. 661. Price of Bread. — This, like the Assize, consisted of a sliding scale. With various prices for the Winchester bushel of wheat, the price at which tlie Peck, Half Peck, and Quartern loaves were to be sold was fixed. 662. Setting an Assize. — In order that “ a plain and constant Rule and Method might be duly observed and kept in the making and assizing of the several Sorts of Bread,” it was provided that the Court or person or persons authorised by the Act to set the Assize of Bread should have respect to the j)rice at which the Grain, Meal, or Flour whereof such Bread should be made, “ shall bear in the publick Market ” in or near the place for which any such Assize of Bread shall be set. They were also required “ from Time to Time, to make reasonable Allowance to the Makers of Bread for Sale, for their Charges, Labour, Pains, Livelihood and Profit, as such Cour 562 THE WEIGHING OF BREAD. 563 shall from Time to Time deem proper/' The bakers were also prohibited from making for Sale any sort of Bread “ except Wheaten and Household, otherwise brown Bread," and such other sorts of bread as were specially permitted. By the above definition, Wheaten bread apparently meant white bread, while Household bread was brown bread. 663. Table of Assize and Price of Bread made of Wheat. — For the guid- ance of the Court of Assize, two tables were set out. The first is the Assize Table. This gives first of all the price of the bushel of Avheat, Winchester measure. This was taken from the public market price ; to this the Court added the sum which the Court held to be an adequate recompense to the baker for baking. Two examples are given — “ If the Price of Wheat in the Market is 5s. the Bushel, and the Magistrates allow Is. 6d. the Bushel to the Baker for Baldng, find 6s. 6d. in Column No. I, and even therewith under No. II will be found the Weights of the several loaves ; but if the Price in the Market is 3s. and the allowance Is., then the Weight of the said Loaves will be found even with 4^." Further directions are given in a note, that the wheaten loaves are at all times to weigh three-fourths of the weight of the Household Loaves. The weight of the loaves is through- out in exact inverse proportion to the figure obtained by adding together the price of wheat and the baker's allowance for making. So, too, the weight of the larger loaves is in direct proportion to the price. The follow- ing is the line of weights for the price of 6^. 6d. per bushel : — Assize Bread. Weight. Wheaten. Household. Price. The Penny Loaf lbs. ozs. 9 drams. 4 lbs. ozs. 12 drams. 10 The Twopenny Loaf I 2 9 1 9 4 The Sixpenny Loaf 3 7 10 4 11 13 Twelvepenny Loaf 6 15 4 .. 9 7 11 Eighteenpenny Loaf 10 6 13 . . 14 3 8 The Price Table gives as before the price of wheat added on to the Baker's Allowance, the latter being fixed in each case by the Court. Then the prices to be charged for the Peck, Half Peck, and Quartern loaves are given. The Magistrates and Justices are also directed “ to take Notice, that the Peck Loaf of each Sort of Bread is to weigh, when well baken, 17 lbs. 6 ounces Averdupois, and the rest in Proportion ; and that every Sack of Meal or Flour is to weigh 2 cwt. 2 qrs. nett ; and that from every Sack of Meal or Flour there ought to be produced on the Average, 20 such Peck Loaves of Bread." It will be seen from this that the sack of flour is estimated to yield 347 J lbs. of bread, which would amount to 86 quarterns of the modern weight of 4 lbs., with a piece 3 Jibs. over. Another point of interest in passing is that the old peck loaf was a twentieth of the average yield of a^sack, making the quartern the eightieth part of such average yield, and weighing 4 lbs. 5J ozs. The following is the line of bread prices, with wheat and allowance taken at 6^. 6d. per bushel : — Priced Bread. Price. Wheat. n. s. d. Household. s. d. Quartern Loaf . . 0 0 5^ Half-peck Loaf . . 1 3 0 11 Peck Loaf . . 2 6 1 10 The Household, otherwise Brown, bread runs throughout at roughly 564 THE TECHNOLOGY OF BREAD-MAKING. three-quarters of the price of white or wheaten bread. Evidently at this time brown breads were not regarded as being an article of luxury and meriting a higher price. It was simply the commonest household type, and was directed to be sold at the lowest figure. The Act proceeds further to set out the machinery by which the Assize is to be set and enforced. Thus returns are to be made weekly of the public prices of wheat, and the assize and prices are to be then fixed. In London, before any advance or reduction is made, a copy of the wheat price returns is to be left at the Bakers’ Hall. In other places the bakers may see such returns at seasonable times at the place where they are kept. Then the assize is published in due form. First the date and place are set forth, and, then it is ordered— “ And in Places where Penny, Twopenny, Sixpenny, Twelvepenny, and Eighteenpenny Loaves shall be made, as followeth ; the Penny Loaf Wheaten is to weigh .... [And so on for the whole of the prices.] And in Places where Quartern, Half Peck, and Peck Loaves shall be made, then as follows : The Peck Loaf Wheaten is to weigh .... and is to be sold for — s. — d. Ditto Household is to weigh, etc.” A further provision was made in the Act whereby the baker has to make his election between making Assize or Priced Bread, as he could not at the same time make and sell the two denominations. The wording of the section ran : — I “ And be it also enacted. That in Places where any six Penny, twelve Penny, and eighteen Penny Loaves shall at any time be ordered or allowed to be made or sold. No Peck, Half Peck, or Quarter of a Peck Loaves shall be permitted or allowed at the same time to be there made or sold ; to the intent that one of those Sorts of Loaves of Bread may not be sold designedly, or otherwise, for the other Sort thereof, to the Injury of unwary People.” The Act further provides that bread is to be always well made, and shall be free from adulteration, as set out in the following words “ The several Sorts of Bread . . . shall always be well made, . . . according to the Goodness of the several Sorts of Meal or Flour whereof the same ought to be made ; and that no Allum, ... or any other Mixture or Ingredient whatsoever (except only the genuine Meal or Flour which ought to be put therein, and common Salt, pure Water, Eggs Milk Yeast and Barm, or such Leaven as shall at any Time be allowed to be put therein by the Court) . . . shall be put into, or m any wise used in making Dough, . . or on any other account, m the Trade or Mystery of making Bread, under any Colour or Pretence whatsoever.” ]\Iost drastic fines were provided for any shortage in weight of bread. The seller had to “ forfeit and pay a Sum not exceeding five Shillings, nor less than one Shilling, for every Ounce of Bread ” deficiency m weight. And if the deficiency were less than one ounce, then a minimum fine oi 2s. 6ri. and a maximum fine of 7^. U. was exacted. Penalties were also provided for enforcing the sale of Priced Bread at the prices fixed by the Under the working of this Act the banker had absolutely no liberty in the way of fixing the prices or weights of his bread. All was decided tor him, and any contravention of the regulations laid down for his guidance was ])unished most severely. 664. Acts Subsequent to 31 George II., c. 29, 1757.— Almost immediately THE WEIGHING OF BREAD. 565 on the passing of the Act of 31 George II. amendments were discovered to be necessary, and further regulations as to the Assize and Price of Bread were found in an Act of the following year, 1758. Following on this were no less than eight other Acts further regulating the Assize of Bread, and in some cases passed in order to render more effectual the Act of 31 G. II. The last of this series was that of 48 George III., c. 70, 1808, the only object of which was again to amend the original George II. Act, and “ to regulate the Price and Assize of Bread.'’ Notwithstanding all these modifications, the Act of George II. was evidently still unsatisfactory, for we next come to another Act, that of 665. 55 G. III., c. 99, 1815. — In this Act it was recited that — Whereas it is deemed expedient that the said several recited [Assize of Bread] Acts, so far as the same relate to the City of London, . . . and within Ten Miles from the Royal Exchange, . . . should be repealed ; and that there shall no longer be an Assize of Bread, or any Regulations respecting the Price of the same, within the said Limits ; . . . there shall be no longer any Assize of Bread within the same City, ... or any Regulations respecting the Price thereof. The right, never again withdrawn, was thus conferred on the Baker to sell his bread at whatever price he chose. The Act further provided for consolidating the various Acts dealing with adulteration of Bread. It also enacted that the Peck Loaf should weigh 17 lbs. 6 ozs., the Quarter Peck 4 lbs. 5J ozs., the Half Quarter Peck 2 lbs. 2J ozs., and every Pound Loaf sixteen ounces. Scales and weights were to be provided for weighing in the presence of the purchaser, and an increased penalty not exceeding Ten Shillings was provided for every ounce deficiency in weight. In this Act a Proviso is found in which French Bread appears. The following is its wording : — Provided always, that no Baker or Seller of Bread shall be liable for any Deficiency in the Weight of any Bread, unless the same shall be Weighed, and the Deficiency of the Weight thereof ascertained, within Twenty-four Hours next following the time of the same having been baked ; and that nothing in this Act shall be construed to extend to or to include such Bread as is usually made, and sold under the Denomination of French or Fancy Bread or Rolls. It should be noted that sale by weight applied to even the Pound Loaf, and that that equally with the larger loaves came within the penal clauses of the Act dealing with short weight. Previous Acts contain the provision that loss of weight of bread must be ascertained within tw'enty-four hours, but so far as the authors have been able to find after searching a large num- ber of Bread Acts, this is the first containing the Proviso relating to French or Fancy Bread and Rolls. This particular Act is one of those classed as Local and Personal Acts declared public and to be judicially noticed.” 666. 59 G. III., c. 127, 1819. — This was also a local and personal Act, declared to be public and to be judicially noticed. It was passed in order to alter and amend the Act of 55 G. III. just referred to. The principal point of historic interest is found in the proviso attached to the section deal- ing with the penalty for deficiency in weight. Such proviso runs : — “ Provided always that no Baker or Seller of Bread shall be subjeet or liable to any penalty for any Deficiency in the Weight of any Bread sold or offered for Sale in his, her, or their Shop, unless the same shall have been weighed by the Baker or Seller of such Bread at the Time of Sale thereof, in the Presence of the Seller or Sellers and the Pur- chaser or Purehasers thereof ; but that this Provision and Exception shall not extend to or include any Bread which shall be dehvered by 566 THE TECHNOLOGY OF BREAD-MAKING. any such Baker or Seller of Bread out of his, her, or their Shop, to any Customer or Customers at the House or Houses of such Customer or Customers ; and that nothing in this Act shall be construed to extend to or include such Bread as is usually made and sold under the Denomin- ation of French or Fancy Bread or Rolls/' The earlier part of this proviso exempts the baker from all penalties tor short weight when the bread is not weighed at the time of sale in the presence of both seller and purchaser. Consequently, if the purchaser did not insist on the bread being weighed, and the seller, as a result, did not weigh it, then the baker was freed from all liabilities for short weight. This exemption was, however, not allowed to include delivered bread, and with this the seller was still under penalties for short weight. The reason probably was that when the bread was delivered the purchaser had no opportunity of seeing it weighed in his presence and also that of the seller. Consequently, the buyer could not waive such right, and the responsibility was still cast on the seller to see that he gave full weight. The next sec- tion of the Act provides that when there is any deficiency m weight, no pro- ceedings shall be taken unless the Bread complained of shall have been produced and weighed within twenty-four hours after the baking thereof in the presence of the magistrates. It will be noticed that again the exempting French or Fancy Bread clause appear in the proviso. 667. Basis of Bread Legislation.— The authors have for many years been interested in trying to find out the causes which impelled the Legislature to make enactments on the sale of bread, and especially the views which were expressed on the subject by members of Parliament during their debates Newspapers of one or two centuries ago did not give such volu- minous reports as those that now regularly appear, and a search for the liistory of the proceedings which resulted in the passing of the various Acts has been long, tedious, anfi not productive of large quantities of infor- mation. Among other works, Cohhett’s Political Eegister has been care- fully examined for the period covering the greatest activity in legislation, but with no success. Although Cobbett was so keenly interested m the Corn Laws, and in other cognate questions, the matter of the Bread Acts seems to have escaped him entirely. Searching in other directions, the records of the circumstances which led to the passing of the Act of 1815 have been the most fruitful in throwing light on the principles which have governed the historical developments of Bread Legislation. 668. Debate on Assize of Bread, 1815.— On Tuesday, April 4, 1815, Mr. Frankland Lewis rose in his place in the House of Commons to move for the appointment of a committee to consider the existing laws with regard to the regulation of the Assize of Bread, and also whether it is expedient or not to have any established assize. The lion, member observed that when the Corn Bill was under discussion it was repeatedly asserted that if the average price of corn were at 805. a quarter, the quartern loaf must be at IfitZ., an assertion which was disproved again and again. But it was b^ome obviously material to inquire in order to set the matter at rest. I here were however, other grounds upon which the inquiry he proposed was desiralile. An opinion prevailed throughout the country that these laws of assize were rather productive of mischief than of good. But yet these laws had so long existed, even, indeed, since the days of King John, that it would be evidently improper to accede without previous inquiry to any such measure as some gentlemen proposed for doing away with these laws altogether. On this ground, then, he conceived a committee of inquiry ought to be appointed. He did not wish to make any perplexing state- ment, but must say a few words as to the operation of the assize system. THE WEIGHING OF BREAD. 567 It was a fact that in places where no assize was resorted to — for it was dis- cretionary with the magistrates to act upon the law of assize or not — the public were more favourably circumstanced. For instance, in the town of Birmingham, where the law of assize was not established, and where wheat was at 655. a quarter, the quartern loaf was sold at 8Jd. by a company, too, which divided 20 per cent, upon their capital. He did not mean to say that this bread was quite so white as that sold in London, but it was of the standard wheaten quality. If, then, the assize laws were really beneficial liow came this difference ? According to the old law, the assize of bread was set by the price of wheat, but by a statute, applicable to London only, which was enacted in 1797, the assize was set by the price of flour ; and this statute, which passed as a private Bill, was actually brought in upon the petition of the bakers of London. To this statute the hon. gentleman attributed the greater part, if not the whole, of the evil complained of in the London assize. The hon. gentleman concluded by formally moving the appointment of a select commitee. After some further remarks tho motion was agreed to, and a committee appointed. 669. Report of Select Committee Appointed, 1815. — The committee just referred to after appointment went rapidly to work, for on June 6, 1815,. the House of Commons ordered to be printed the “ Report from the Com- mittee on Laws relating to the manufacture, sale, and assize of bread.'" Copies of this report are at the present time very scarce, but thanks ta the Librarian of Lincoln's Inn Library, the authors, after wading through vast masses of old Parliamentary papers, have succeeded in unearthing a copy, of which the following is a 'precis. It cannot fail to appeal to those interested in the history of the development of bread legislation. The Committee proceeded in pursuance of the orders of the House, to examine and compare the statute called “ Assisa Panis et Cervisise," made in the 31st. year of Henry III., with various other ordinances issued since that date. They find that the 31st Henry III. was (at the petition of the Bakers of Coventry) an exemplification of certain ordinances of Assize made in the reign of King John, the purpose of which appears to have been to regulate the charges and profits of Bakers ; it being stated in the Act “ that then a baker in every quarter of wheat (as is proved by the King's bakers) may gain fourpence and the bran, and two loaves for advantage ; for three servants three halfpence, for two lads one halfpenny, for candle one far- thing, for wood twopence, for his bultel (or bolting) three halfpence," in all sixpence three farthings, and two loaves for advantage. [That is to say, on the Assize prices the baker's profit per quarter of wheat was fourpence and the bran, and in addition sixpence three farthings to cover his expenses of manufacture. He also had two extra loaves for his own advantage.] The Committee, observing the allowance thus stated to be made to the bakers was partly in money and partly in bread, proceeded to examine in what way the table of assize was constructed for the purpose of ensuring them this allowance. They took the case of “ wheaten bread " as an ex- ample. They find that of this bread it is stated in the table, “ When wheat shall sell at \2d. the quarter, the farthing loaf shall weigh lOZ. ID. 6J.," which weight (as was usual in those times) being expressed in pounds, shillings, and pence, the Committee find the pounds to be the Saxon or Tower pound, which is to the Troy pound in the proportion of 15 to 16. They then cal- culate that the quantity of wheaten bread expressed in the Statute by the denomination of lOZ. ID. 6J. is equal to 10-575 lbs. Troy, and 8-7087 lbs. Avoirdupois ; as one loaf of this weight was to be sold for a farthing when 568 THE TECHNOLOGY OF BREAD-MAKING. a quarter of wheat was at \2d., it follows that 48 such loaves (which weigh 418-02 lbs. Avoirdupois) was the exact quantity of bread which was to be sold for the price of a quarter of wheat ; whatever bread could be made from it over and above 418 lbs. was for the baker’s advantage, and this is stated in the statute to have been proved, on experiment, to have amounted to two loaves ; and if these were peck loaves, 452 lbs. 14 ozs. of wheaten bread was the quantity obtained by the King’s bakers from a quarter of wheat. The Committee then proceeded to examine whether the quantity of bread at that time obtained from a quarter of wheat agreed with the quantity asserted in the statute. They appeal to the record of an experiment re- ported to the House in 1800, by which it appears that the flour from a quarter of wheat weighing only 55 lbs. a bushel, and dressed after the mode then in use for preparing flour for the London market was baked into 433 lbs. of wheaten bread, and 25 lbs. of household bread. The Committee are thereby assured that when the baker was forced to sell no more than 418 lbs. of bread for the price of a quarter of wheat, he really obtained in surplus bread the two [peck] loaves for advantage which the Statute professed to allow him. The money allowance appears to have been for the purpose only of repaying the baker’s charges for grinding and baking, while the advantage loaves were for his maintenance and profit. The Committee then proceeded to trace the successive alterations which had taken place in these two allowances to the bakers, and with regard to the payment in money, they found it was from time to time increased and altered : in the 12th. of Henry VI. it was raised to two shillings per quarter ; and the Committee begged leave to point out that a large quantity of this allowance appears to have been appropriated to the baker and his family who by 31 Henry III. were providedjor by the advantage loaves : — “ Anno 1405, 12 Henry VII., and as the said Book of Assize declareth,” “ when the best wheat was sold at Is., the second at 65. Q)d., and the third at 65. the quarter. The Baker was allowed. s. d. “ Furnace and wood . . . . . . . . ..06 The miller . . . . . . . . . . ..04 Two journeymen and two apprentices . . ..05 Salt, yeast, candle, and sack bands . . . . ..02 Himself, his house, his wife, his dog, and his cat . . 0 7 In all 2 0 And the Branne to his advantage.” [Examination of the figures does not altogether bear out the Committee’s contention. The advantage loaves were not the only provision for the baker in the days of King John. He then had 6|J. for his expenses, and 4J. allowance and the bran in addition to the advantage loaves. The loaf allowance and the bran were the same at both periods, while in King John’s time the total money allowance was lOfJ., against 2s. Od. in 1405. From the prices given for wheat the value of money was about six times as much in the reign of John as in the time of Henry VII., therefore \0%d. in John’s reign would be equal to 10|J. x Q = 5s. 4t^d. The baker’s allowance was thus comparatively much less in 1405.] For the long period of 556 years the quantity of bread that was required to be sold for the price of a quarter of wheat remained the same, that is to say 418 lbs. But the money allowance was from time to time raised, until in the time of Anne it was at 12 very narrow frontage and plenty of depth. The sketch has been prepared on this assumption, and shows a bakery standing on a piece of ground 15 ft. 4 in. in width. This might be still further diminished by lessening the width of the passage round the stokehole, which in the plan is 3 ft. wide. By resorting to the plan of having the oven fired at front and within the bakehouse. Fig. 4, Plate VIII, the total width might still further be reduced to 10 ft. inside and 12 ft. 4 in. external width. Or even in this case the oven might be fired at the back by arranging a spiral staircase or step- ladder down into the stokehole from over the oven through the flour store above. Such very narrow sites are not, however, likely to often occur, and the staircase arrangement is not recommended. As drawn, it is assumed that no light is available from the sides, and accordingly small windows Plate VIII. Plans of Single Drawplate Oven Bakery. 10 a p REFERENCES. A. Gas Engine. B. Dongh Divider, c. Moulding Table. 'E. “ Single Blade ” Kneading Machine. F. Drawplate Oven. D. Stoke-hole. G. Flour Store. H. Blending Hopper, Sifter and Shoot, j. Drawplate. K. Space for Dough Trucks and Proving Dough. L. Front-fired Drawplate Oven. 600 BAKEHOUSE DESIGN. 601 are placed over the ovens into the bakehouse. This plan shows the position of flour-blending, sifting, doughing, and dividing machinery, arranged in the bakehouse, and also parts of the same overhead. The engine-room is in front of the bakery, and beyond that is the bread-room. A bakery such as this forms an interesting and fairly complete installation. With this plant, especially where the drawplate has over it a peel oven, or is of the two-deck variety, an extensive and varied trade may be done, and in- stances are known in which over a hundred sacks per week have been regularly turned out with similar equipment. The machine plant indicated could very well turn out sufficient work to warrant the erection of another oven beside that shown, maldng of course the bakehouse correspondingly wider. With Fig. 46 . Oven for Small Bakery. Fig. 47 . Interior of Small Machine Bakery. 602 THE TECHNOLOGY OE BREAD-MAKING. increased width rearrangement of space would permit the depth to be reduced. Fig. 46 shows an oven such as this bakery might have and Fig. 47 a view of a bakery fitted with two-deck draw-plate ovens and machinery on a small scale. 698. Shop and Overhead Bakery. — ^The designs given on Plate IX take into consideration a business which is supposed to be in the main street of a good neighbourhood where the exigencies of the circumstances demand both bakehouse and shop to be in close proximity. It is assumed thrd the only access to the premises is from the front or street side, there only being at the back a limited amount of air and lighting space, which cannot be utilised in any way in connection with the manufacturing operations of the business. Regarding the shop itself, much must of necessity be left to the nature of the business and the individual taste of the proprietor. It goes without saying that window space is required for the display of goods ; this is pro- vided by two windows, each about 10 ft. in length. On the one side of the shop is a counter, and the other is fitted with a table, which may also be used for counter purposes. Toward the back of the shop some small tables are placed, for the purpose of serving light refreshment — tea and coffee. Descending from the back of the shop is a staircase leading to lavatories and retiring rooms in the basement. These are indicated by dotted lines on the ground-floor plan. A passage from the bottom of the staircase leads to one set of lavatories and w.c.'s on the left hand. Another similar set is reached through the room shown under part of the bread-room. This basement room, with the adjoining conveniences, could be retained for the staff, the others being reserved for the accommodation of customers, and both kept separate and distinct from each other. This basement might also be used for the preparation of light refreshment to be sent up by a small lift fixed by the top of the stairs. It being assumed that the only approach to the building is from the front, means of ingress and egress to the bakery have been provided by a side passage on the right hand of the shop ; this goes right through to the back of the building, and has doors leading into the bread- delivery room and the office. As it is no longer possible to have a new underground bakehouse, the bakery is shown overhead, similarly to the not unusual plan of having hotel kitchens, etc., at the top of the building. Let us now rapidly run through the general arrangements of the bakery. As aheady explained, the shop is on the ground floor, with lavatories in back part of basement, opening out in area behind. At the rear of the shop is the bread cooling and delivery room. On the first floor is the bakery, containing the ovens, loaf dough divider, and moulding tables. Other machinery and the engine are arranged on the second floor, while the flour stores are on the third floor. A more detailed examination of the arrangements may be made by following the flour from its entry into the place to its departure as bread. Being situated on a main and busy thoroughfare, all flour will have to be delivered either early in the morning or preferably late in the evening when the shop business is over. The flour van would be backed against the side entrance and the flour drawn up at once to the third floor by the sack hoist some three or four feet in from the door. The hoist itself is fixed overhead in the flour-room, and draws the sack up through trap doors on each landing ; in this way flour or other material may readily be brought from a van at the side entrance to any desired floor. Where considered necessary flour- blending machinery will be fixed underneath the third floor, and arranged so as to be worked from the flour store (paragraphs 726 to 728) . The hopper. BAKEHOUSE DESIGN. 603 through which the flour passes to the sifter, is also on this floor, the sifter itself being bolted up underneath the joists, as shown on the sectional dra\Yings. From the sifter the flour passes into the doughing machine. The sifted flour, together with water from the tempering tank and yeast or ferment, as the case may be, is converted by means of the kneading machine into dough. For ferments and sponges a room has been provided in one corner of the machinery room, where they may be kept at an equable temperature and free from draughts. The size of this room may of course be varied to suit particular requirements. A cake machine and whisk are shown on the first floor, but these and other machines required could easily be arranged to suit amended requirements. The doughs are allowed, after being made, to stay on the second floor until ready, and are then cut out of the troughs and discharged through a hopper on to the moulding table or into the dividing machine on the floor beneath. The machinery as shown is driven by a gas engine fixed in the one corner, from which runs a hne of shafting along the wall. On the first floor are the divider, cake machine, whisk, the moulding tables, and the ovens. Although the authors are advocates of draw- plate ovens, they have here shown a series of peel ovens, as these are still largely used with mixed trades such as this bakery would be suitable for, but draw-plate ovens could be arranged if preferred. The ovens shown are tw^o-deck, fired from the back, and should preferably have separately fired baking chambers giving absolute control of temperatures (see para- graph 756). The fuel for these ovens is coke, and this, on being brought as usual to the bakery in sacks, is hoisted direct to the third floor and taken into the coke store. The ashes are put into a portable closed sanitary* bin for removal once every twenty-four hours. This bin is sent down bodily by the sack hoist, and handed over to the dustman on the occasion ofpiis daily visit. At the far end of the stokehole is fixed a small vertical boiler for the production of hot w^ater for general purposes. The flue from tlie ovens is carried into a chimney stack built against the back wall, where it cannot become a nuisance to neighbouring property. The ovens them- selves are supported on girders carried between the back wall and the wall dividing the shop from bread room, and resting with their front ends upon a girder carried by the pillars and side wall. The baked bread is packed in portable racks, and taken below by means of a lift into the cooling and delivery room. From the cooling-room one would naturally hke to be able to load barrows and carts at the back, but this, according to the conditions, is impossible. Arrangements have therefore been made for delivering through the side door. A delivery clerk checks the bread as it goes out. The bread racks should not exceed 2 ft. in width, so that they may pass each other in the 5 ft. passage. This passage might be used at night for the purpose of keeping barrows, as some six or eight could readily be stowed away in it. A door leads direct from the cooling-room into the shop. Through this all shop goods would be brought, and, if foundjabsolutely necessary, bread barrows could also be filled this way in the early hours of the morning, in addition to the use of the side entrance. On this’ floor is placed the office, which, as situated, controls the shop, the sideTpassage, cooling-room, and delivery clerk's desk. From the cooling-room, through a door leading into the backyard, are reached the workmen's lavatory and w.c. With sufficient space at the rear this accommodation might well be enlarged. Such, in brief, is the outline of the bakery and^shop fitted for a large and high-class family business in a first-rate locality, but on a"^ severely restricted site. The exigencies and nature of the business, together with the actnal size and proportions of the premises, must all affect the precise REFERENCES TO PLATE IX. A. Blending Hoppers. B. Flonr Sifter. c. Kneading Machine. D. Tempering Tank. E. Water Tank. F. Hoist. G. Dough Divider. H. Cake Machine. I. Whisk. j. Engine-room and Gas Engine. K. Lavatory and Cloak Room. L. Basement. M. Men’s Lavatory. Ah Shoot. B^. Water-heater, c^. Stoke-hole. D^. Two-deck Peel Ovens. N. Wall supporting Ovens. o. Side Entrance. p. Open Yard. Q. Delivery Checking Clerk. R. Office. s. Counter. T. Tables. u. Cooling and Delivery Room. V. Down to Lavatory, w. Shop. X. Lift. Y. Hoist Trap Door. z. Ferments and Sponges. Eh Flour Store. F^. Dough Room. Gh Column. 604 Plate IX. Plan of Shop and Overhead Bakery. 605 606 THE TECHNOLOGY OE BREAD-MAKING. nature of arrangements in each individual case. Such plans as are here given can only touch on the general principles involved in the arrangements, which in themselves lend themselves readily to considerable modification. 699. Bread and Cake Factory and Automatic Machine Bakeries in General. — ^No attempt will be made to describe the buildings and equipment suitable for a very large business, particularly as the equipment is not very different to that which forms the subject of this paragraph. The plant in very large bakeries requires to consist merely of more units rather than units of larger size and capacity. It may be said at once that modern development in Great Britain tends to replace small bakeries by others of medium size rather than with very large ones — the latter not being necessarily at a very great advantage over the former owing to the difficulty and expense of delivering bread over a very large area. In large cities it would be better policy to erect several bakeries of medium size in preference to one large bakery, and with centralised office management, and a good organisation to super- vise the various bakeries, there is the less reason to fear ill effects from decentralisation in regard to manufacture; because with the automatic machinery available to-day it is impossible for the output to fall short of the standard, or for the cost to exceed the same, owing to the automatic machines acting as pacemakers. It is necessary of course to have efficient foremanship in each bakery, but as this is requisite in any case, there is no disadvantage in this respect. For the purpose of our present observations it is necessary to adopt some classification, in regard to the size of bakeries, in order to convey some idea of the extent to which the specialisation of machinery and equipment should be carried. 700. When Machinery Pays. — It is one of the most important questions when designing a modern bakery to determine exactly how far the provision of machinery should go. At the time of building, when a given trade has to be provided for, some machines may not be worth installing which it is essential to have in a few years’ time when trade has growm to proportions making their employment highly remunerative. If, however, no clear idea of this possibility exists at the time the building is erected, it may be impossible to provide the necessary space, or to make suitable arrangements, owing to the later wants not being provided for. The standard of trade for a medium-sized bakery may to-day be set at approximately 500 to 700 sacks (280 lbs.) per week, because this is the maximum output of one automatic bread-making plant (see paragraph 746). The size of this unit is determined by technical considerations, but it may be accepted for our purposes that 2,400 2-lb. loaves per hour is the maximum output of an automatic plant which has been found practicable. If a bakery requires to deal with more than this output, more than one plant must be installed. The limit as regards maximum output per week having been definitely ascertained by multiplying the hourly maximum by the weekly working hours (examples ; 2,400 2-lb. loaves per hour= 12 sacks per hour x 60 hours Avorking per Aveek == 720 sacks ; or 2,400 IJ-lb. loaves = 8 sacks per hour x 50 hours Avorking per Aveek = 400 sacks per AA'eek, etc., etc.), it may be asked, AA'hat is the loAvest output per AA'eek, on Avhich such a plant AA'ould pay ? The ansAver to this question is not a simple one — many considerations go to determine the correct course in each in- dividual case, but it can be affirmed that it AA^ould neAmr be advisable to attempt an ansAA^er Avithout the assistance of the bakery engineer Avho specialises in automatic machinery. Taa'o bakeries Avith precisely similar, and on the face of matters perfectly sufficient outputs, may be very differently placed as regards the composition of their respective trades. It may pay brilliantly to have a full installation in the one case and yet not in the BAKEHOUSE DESIGN. 607 other. Such matters can therefore only be determined after full investiga- tion of the whole of the circumstances. It will be appreciated that the authors can only lay down the general rules which should be followed, and that such approximate facts, as are here quoted, apply to average cases. The minimum trade for a full automatic plant may be taken at 250 sacks (280 lbs.) per week of reasonably uniform loaves. On this output no one need hesitate as to the remunerativeness of the installation, but it may be here remarked that owing to the uniformly better bread which would result under tolerably good management in the bakehouse, an increase in the sales may be looked for; this increase will be all the greater if the sales are smartly pushed, although that is not what is here meant — ^the increase referred to is automatic and due to a better article. To the un- initiated this may sound “ too good to be true,’' but the statement is never- theless based upon a well authenticated fact. Any one installing a plant on a trade of 250 or 300 sacks will therefore, in all probability, soon have a larger trade Avitb which to keep it employed, and all increases will inevitably bring down the cost of production per sack, because no increase in the number of men working the plant is required for working it to its fullest capacity. For bakeries with trades under 250 sacks per week smaller plants are made, both as regards the actual machines as well as in certain combina- tions, by reason of fewer machines being employed in conjunction with intermittent working. Thus, a so-called semi-automatic plant will pay in the case of a fairly uniform trade of 100 sacks per week and upwards, and the cost per sack in labour will be only fractionally less good than that obtained from full-sized installations. Under one hundred sacks per week the employment of a divider and a “ Flexible ” moulder (that is a moulder equally adapted for turning out tin, cottage or coburg bread as well as smalls) will pay down to weekly outputs of 60 or 70 sacks. This is contrary to the opinion still very generally held, but as actual cases exist which prove the statement, the authors do not hesitate to give it all the weight they can command. Under 100 (one hundred) sacks per week no up-to-date bakery should be without at least a divider, provided the machine is designed on the proper principles, and does not fell or otherwise injure the dough. It is no use employing a machine merely for the sake of having a machine, and many a user loses in reduced quality all and more than he can save in labour. Good modern dividers are very accurate, much more so than any commer- cially obtainable hand-scaling, they act as pacemakers, and are absolutely reliable machines if looked after with reasonable care and kept clean. Bakers with trades no greater than 25 sacks per week in bread should by no means assume that a divider will not pay ; even on such comparatively small outputs as 25 sacks (280 lbs.) per week these machines pay well in many instances. It may be taken that a suitable divider will pay in any business doing a reasonably uniform bread-trade and employing three men. 701. Large Bakeries. — Returning now to the subject of large bakeries, and having determined upon the nature of auto -machinery to be installed, the question of ovens should next engage attention. The subject of ovens is fully dealt with elsewhere (paragraphs 749 et seq.), and for factory working, i.e. wholesale production, no type can to-day be really seriously considered in Great Britain other than the draw-plate oven — or perhaps in Scotland and some parts of Ireland, the “ Coverplate Oven.” The size of baking plate must be determined to suit the style of loaf. Cottages, coburgs or tins, are most conveniently dealt with in one sack batches and on plates with a maximum width of 6 ft. “ Oven-bottom ” or close-set bread, if not 608 THE TECHNOLOGY OF BREAD-MAKING. in association with any of the first-named varieties, can be handled perfectly with plates up to 8 ft. 6 in. in width, as can also “ Scotch Bread.'’ Batches may be taken to vary from one sack cottage to sack “ Scotch ’’ batches, but to illustrate the procedure, we will adopt the former as a standard. Assuming a full size auto-plant to be decided upon, this will have an output in 2-lb. loaves of 12 sacks per hour. The ovens will bake continuously one batch per hour — hence 12 one-sack drawplate ovens will be required in such a bakery. The preceding remarks (in paragraph 700) refer mainly to machines dealing with the dough after it has left the kneading machine. Naturally, hoists, sack-cleaners, blenders, storage hoppers, sifters, tempering tanks, and kneaders have all to be considered ; but as these have been longer on the market and are better understood generally than the automatic plants, and are also fully referred to in their respective chapters, no special reference is here made to them. The authors have advisedly enlarged upon the auto plants because they are to-day the key to successful designs for large bakeries, and because no architect can be properly instructed as to the nature of buildings required, before the bakery proprietor is quite clear as to his requirements in regard to machinery. The architect who has had anything to do with modern machine bakeries, will agree that his clients do best first to consult the bakery engineer, who will prepare such plans and particulars as will alone make it possible for him to give his client a perfectly designed bakery. This may be a new order of things, but it is undoubtedly necessary to prominently advise the above course if mistakes are to be avoided, and the authors consider no other apology necessary for introducing so lengthy a preface to the following description. 702. Modern Bread Factory. — The drawings on Plate X show a well-de- signed modern bakery for bread and confectionery, with an output up to 7C0 sacks (280 lbs.) in bread per week. The site is assumed to have been chosen with due regard to distribution of the output among customers. It should therefore lie as centrally in the district to be served as possible, and if in a hilly country, as far as practicable above such district. As it is more difficult to give a good plan with access to a street on one side only, such a case has been chosen. Everything is kept as compact as possible, so that the design may give some idea as to the minimum space required. The scheme is such as also to keep the cost of buildings low, because money should be spent on the equipment which is the money maker, rather than upon palatial buildings, or extravagantly large or costly sites. The build- ings are all of one storey, except for a sufficiently large flour store and dough- ing room. Hence buildings are light and cheap, and supervision easy. As such a bakery will mostly be found in a town of some size, it is unnecessary, and indeed unusual at the present time to provide for flour storage on a large scale, unless a speciality is made of blending (see paragraphs 725 to 728). It is better to have the flour delivered as it is required with only a few days’ supply in hand. Flour blending is also the exception rather than the rule, and because adequate means for blending, storing and weighing off are costly and not necessarily remunerative, they have not been shown on the plan under notice, but full particulars will be found in a separate chapter. The flour is shot into a hopper on the floor of flour store from bags which correspond to the unit adopted. For one sack ovens, two sack batches would be kneaded and two sacks of flour (280 lbs. each) would be the quantity shot into the hopper (a). An elevator conveys the flour to a sifter ih) shown in the doughing room and fixed above the kneader (c), or in one with it. The tempering tank [d) will be found close at the side. The dough when BAKEHOUSE DESIGN. 609 ready is discharged into movable trucks, which remain in the doughing room until sufficiently proved. That stage having been reached, the truck is moved to the hopper (e) in the dougli-room floor, and the dough is cut out of the truck, into handy pieces not exceeding 28 lbs. each, and dropped directly down a shoot (/) into the hopper of the dough divider {g ) ; this machine forms part of the automatic plant [h), and no further labour is entailed until the finished loaves emerge and are placed in tins or upon setters ready for the ovens after a further short period of rest. The auto- plant will obviously require to be run at a speed to suit the oven capacity. On the plan under notice 6 two-deck draw-plates (^) are shown — these will therefore require a batch to be ready every 5 minutes in order to give the required output of 12 sacks per hour. After being baked, the loaves are swept off the plates on to tables to facilitate rapid handling and are con- veyed to the bread room on suitable racks fitted with wheels and castors. Such a bakery would be run at full output with a staff of 14 men exclu- sive of foreman — this includes taking flour from flour store and delivering the bread to the bread-room. With 50 working hours per week and includ- ing foreman, this would give 40 sacks per man, per week, and is easily possible with a uniform trade, totalling 600 sacks per week. A simple calculation will show that by working the ovens and machinery longer hours by the aid of more men, the output can be raised without increasing the working hours per man — for instance 18 men would give 720 sacks, each man still putting in 50 hours only. The confectionery department is shown as a separate room, fitted Avith 4 ovens (built in two-deck form), each with a separate furnace. Cake machine (g) and whisk {k) are also provided. These confectionery ovens are served from a stokehole and stack, common to the bread ovens as well. Electric motors are shown for tlie purpose of providing power where required, separate motors being fixed for the flour hoist {1), the doughing room, the auto-plant, and the confectionery department. The other arrangements of the buildings call for no extended comment, as the plan will give all information required. The flour and doughing rooms and the auto-plant annexe are heated by hot water. The stable yard and arrangements are adequate for a district not too large (as is intended) and the office is well placed to control all inward and outward traffic. It may be of interest to add that the plan is very similar to that of a midland bakery, aa hich has been in very successful operation for nearly three years, and to the entire satisfaction of its proprietor. The extension shown in dotted lines is provided more Avith a view to the possibility that the trade may groAV in complication than to enable a greater output to be obtained. It Avill be clear that so long as a 2-lb. loaf trade only has to be catered for the calculation of oven accommodation required is simple, but if a change to a greater number of varieties or a smaller size loaf should occur in tlie course of years serious difficulty might arise, if space for more ovens did not exist. R E Plan of Modern Bread Factory. Plate X REFERENCES TO PLATE X. © . PLH S ^ ^ . td o ^ ©-2^ o ^ CS ^ 4:3 o ^ . o o ;-i o S ^ b d ^.S g I d ^§-2^ ^ ©.S^-gP^ g|^0 § a. U ^ §« E« . 'tS >i ^ sl t 3 rn _§ (D 02 > O bO G M G . © 7:3 ^ P O eg X . o 73 • W ® ® © 02 T3 rG O Go W c ^ § 8 i PMgpiHHO^p02O002^> « § «(S gS- 5 0|-g S a I ® o 2 o^mho^o) . ^ cS rS G ® 2^ W W . -^-4^ ^ddo'dccHd^^MjH'N dj'M'G^'o'fiH 'd''rt " 6 .2^ G m 03 ^6 S bC G o G ® Si ' Gh.^ 2 w ft § • I §>sF'^ •|“'=^'S I . M)dG®G'o G 5 ’ 3 i^ i£sgssg |l as |j.s^g-iE| £| fifeOOWMW» 2 p§OWmW Ah bo © > o ^ 03 dn © Tb'b I 2 § o D ^ Ti A g O 03 O O O P © d ^ G bo bo © A ® , r^ r^ ^ ^ eg C P ® ^ 'g ^2 J I ^2 i d-d d d « dj dfiHf.;CJKMdMiG§ ow'ers and wnigh all kinds of pros and cons wdth much care, but this is w'orse than useless if a supposed saving of a little power in a machine is to be nullified by badly designed accessories or transmission arrangements. The fact is, that as regards power absorbed by machines, the user may wnll leave that subject to the engineers ; it will pay him better to confine his inquiries, wdien selecting machines, to the question of their efficiency for his daily w^ork. The machines that will pay him best are those which pro- duce the finest article — no matter wLat their price may be or the horse pow'er they absorb — especially as it is rather in the nature of things, that the machine w hich punishes the dough least is also likely to use the least horse power. 718. Striking Gears. — For shifting the belt from a loose pulley to a fast pulley, or vice versa, a fork is used, by means of which the belt is pushed sidew'ays until it has changed its position on the pulleys as desired. The fork should make contact with the belt at a point as near to the pulley as possible, and ahvays so that the belt runs from the point of contact to the pulley. The gear for actuating the fork should be such that it locks itself in the “ on and “ off positions, and all striking gears should be readily acces- sible, so that shafting or machines may be stopped as quickly as possible in case of emergency. Where the starting of a line sha-ft involves the starting THE MACHINE BAKERY AND ITS MANAGEMENT. 625 of any running gear out of sight of the person operating the gear, a bell should be fitted so that it may be rung as a warning before the shafting is set in motion. Fast and loose pulleys should, however, be provided for each sub-section of shafting, so that each may be quickly stopped in case of emergency. This has the further advantage, that very frequently much running of sub -sections may be saved when only a portion is required to be in motion. 719. Rope Driving. — In place of belts ropes are at times employed. In these cases the rope runs in a V-shaped groove in the pulleys. The same rule as to relative speed applies to rope drives as to leather belts. Rope possesses an advantage in that it can be bent in any direction, and thus a drive may be taken round corners, when power has to be transmitted in a direction other than at right angles to the line of shafting. With very long drives ropes are preferable to belts ; when, for instance, a yard has to be spanned, to carry power from one building to another. The rope should then be supported at intervals on “ jockey pulleys, and if passing through the open air should be protec ted from wet. There are, however, not likely to be many cases in connection with bakeries where a rope drive is really necessary, and it must be borne in mind that it is not possible to arrange for fast and loose pulleys with a strike gear. If a rope drive is required to be so arranged that it can be stopped, a clutch is necessary, and it is better to avoid the necessity for such complications if possible. 720. Chain Driving. — An excellent and quite modern development of power transmission is the chain drive. It is suitable for very short centres, should be of the “ silent chain type, and be arranged to run in a casing with an oil bath, and can be relied upon absolutely. It can also transmit very considerable powers, and although expensive to instal, will .last for many years if suitably proportioned. Needless to say, it can only be em- ployed for parallel shafts running in the same direction. 721. Gear Wheel Drives are entirely satisfactory if properly designed and made. Even spur wheels (for parallel shafts) and bevel wheels (for shafts at various angles) can now be made virtually silent, but as these devices are expensive and need special designing to suit each case, they should be avoided as far as possible. In any case, no general data can be of sufficient use to justify the large amount of space which would be required to deal with this subject adequately. It is best when apparently faced with problems of this kind to place the matter in the hands of the bakery engineer. 722. Special Drives. — There is one special double crank gear contained Fig. 48. “The Almond” Right-Akgie Drive. 626 THE TECHNOLOGY OF BREAD-MAKING. in an oil-tight casing, to enable the working parts to run in a bath of oil, which is so compact and useful in occasional awkward cases that it deserves special attention. It is sometimes imperative to place a machine in a posi- tion at right angles to that in which it was designed to work ; it may be impossible to drive it by a quarter twist belt or by an arrangement with “ jockey pulleys. The “ Almond right angle drive, of which an illustration is given. Figure 48, then steps into the breach admirably by enabling an ordi- nal open belt drive to be converted by its use into a drive at right angles. As it is within the knowledge of the authors that this gear works well, without any trouble, for a number of years it would appear to be an apparatus which can be safely recommended. 723. Lubrication and Maintenance.— The modern device for ensuring lubrication has already been fully dealt with as regards bearings and loose pulleys for shafting. The older methods are not referred to, as modern developments and advice for future conduct alone form the subject of this chapter on machinery. It may be as well, however, to say that oil is con- sidered the only suitable lubricant for shafting, at least in the opinion of the authors, as solid grease lubricant, excellent as it is for bakery machines proper, involves more constant attention than can be relied upon v here bearings, etc., are out of reach and in inaccessible places. That no preju- dice exists against solid lubricants, will appear quite clear after a perusal of the description of bakery machines. In connection with lubrication, special attention requires to be drawn to the necessity for using bearings from which leakage or overflow is impossible ; as this is obvious, nothing further need be said. As to maintenance, it cannot be sufficiently insisted upon that the only proper course is to appoint two men specially, whose duty it shall be to carry out certain specified duties periodically. The bakery proprietor should keep a book in which he enters these duties in full— set out in un- equivocal language — ^he should add further items, as experience shov s up weak spots, so that these may be safeguarded in future, and he should satisfy himself that the person appointed has attended to his duties at the specified times in a proper manner. The object in appointing two men is to provide against emergencies. There will then always be at least one competent person available to do the work, if each of the two is made to take the duties referred to for alternate months. The task of preparing the book of instructions is not so formidable as might appear at first sight. The manufacturers of ovens, machines and motors provide (or should provide) proper instructions ; and if these are taken as a basis, and common sense, assisted by the engineers, be used, com- plete rules will not be difficult of compilation. That the maintenance of the proprietor’s plant should be properly organised by the proprietor must be evident, because that course is absolutely indispensable in his own interests. It is no use to blame the men when something has gone wrong ; it would be much better for the proprietor to blame himself for not having made adequate provision against contingencies. If this sensible course is followed, the proprietor will soon find a remedy, which will never be the case if the matter is simply left in the hands of the men. As regards upkeep of shafting and gearing generally, the authors fear that the majority of users rarely trouble themselves until defects force themselves upon their notice. They have already said that spares for repairs of belts should always be kept handy. It is now suggested that shafting is as much an essential of an installation as the engine or the machines, and that it and all its appurtenances, as well as engine and machines, should be kept absolutely clean. If cleaning is properly done from day to day it is THE MACHINE BAKERY AND ITS MANAGEMENT. 627 done in an astonishingly short time. If it is neglected until gear has to be “ dug out '' it is nearly a hopeless task. No proprietor should be satisfied ^^dth his bakery unless shafting and all machinery be left perfectly clean inside and out at the conclusion of the day's work. This is no counsel of perfection ; there are plenty of bakeries in which this is done, but there are far more in which it is otherwise. This cleanliness is not only essential for the proper upkeep of the machinery, but it is indispensable from a hygienic point of view, as well as from the business standpoint. Let each bakery o\^er throw his bakery open to public inspection all day and every day, and if it be kept in the condition in which it should be, this plan vdll not only compel the proper appearance and condition of the establishment, but will prove the best possible advertisement. In such cases where this plan has been tried, it has given excellent results and has led to increase of busi- ness. 724. Flour Hoisting, — Flour being, for reasons explained in paragraph 693, usually stored at the top of the building, adequate means for hoisting are among the primary requirements of a power-driven bakery. In many cases a covered cartway is formed in connection with the bread-room either within the four walls of the main building or as shovm at T, on Plate X. In the former case square holes are cut vertically above one another through every intermediate floor, in such a position that the loaded flour lorry can be conveniently placed immediately under the openings. Each floor opening should be fitted with hinged flaps, normally completing the floor and preventing all danger from open holes. These flaps should be stoutly constructed and made to hinge upwards ; a hole is cut in the centre of the joint between the two large enough to allow the cast-iron weight-ball, which serves for causing the hoisting chain or rope to descend, to pass un- obstructedly . The trap-doors should be railed off, but if this is not per- rnanently possible, movable guard rails should be placed in position each time the hoist is used, to prevent risk of injury to passers-by. If the flour sacks are to be hoisted outside the main building, the pulley over which the hoisting rope passes is supported on a projecting beam or cathead. To prevent the flour from getting wet and to avoid the admission of cold air into the flour store as far as possible the cathead should be enclosed, and a continuation of this enclosure should be carried right down to within a convenient distance of the lorry ; where the lorry stands in a covered yard, this enclosure or trunking {usually called a ‘‘ lucombe ") merges into the roof of the yard and is joined to the same in such a manner as to be water- tight. Wherever the lucombe gives access to a floor, Le., at each floor to which flour is intended to be hoisted, trap-doors as described should be fitted, thus practically avoiding all danger to operatives in “ landing " the sacks and detaching them from the hoisting rope. The centre of the hoisting rope should be clear of projections by about 2 ft., and the internal dimensions of a lucombe should not be less than 4 ft. square. The Sack Hoist itself, except in such rare cases where it may be direct coupled to an electric motor, should preferably be of a type employing a friction drive. There are various hoists upon the market which are quite satisfactory, but none are simpler, more efficient and reliable, free from necessity of repair, or easier to work than the one here illustrated. Fig. 49. , The driving pulley will be seen close to the frame to the left of the illus- itration, it^can be driven in either direction by arranging an “open" or . drive. It usually runs free, and is therefore a loose pulley. I he hoisting drum, grooved to take the highly flexible steel wire rope, is •pressed to the right into the brake drum by a spring contained in the pro- j jection shown to the 'left of the framing. The drum is therefore normally 628 THE TECHNOLOGY OF BREAD-MAKING. Fig. 49. — Sack Hoist. and automatically “ on the brake.^’ A slight movement of the lever on the right disengages the drum from the brake and allows any suspended weight (the ball shown is sufficiently heavy) to descend. On letting go the lever the drum instantly returns to the brake and comes to a stop. A slightly greater movement of the lever than that referred to engages the other end of the hoisting drum with the pulley and causes the hoisting rope to be wound in, thus raising any weight attached thereto. The action is quick, safe and noiseless and allows of very delicate handling. These hoists have been in constant use for very many years and are capable of hoisting hundreds of sacks of flour per week each. They are made in various sizes, to suit the length of lift and for weights up to 5 cwts. The fixing of the hoist is “uni versa!’ ’—that is to say it may be fixed to suit practically any local requirements. The best plan is to hoist direct from the drum, as each pulley over which the rope has to run means wear and tear to the latter. In practice the lever is of course worked from a hand rope carried to a convenient position. v j r The hoist shown is fitted with a wire rope, but it can also be supplied tor use with a chain. The rope is, however, rather the safer appliance because it will not break without warning. The wear of a wire rope can be readily detected by the gradual breaking of the strands. As the broken ends stick outwards and are sharp as needles, the occasional passing of the bare l^nd along a wire rope will soon draw attention to wear. A rope is sound so long as tlie surface is smooth to the touch all along its length. Chaiiis do not necessarily give any sign of weakness, as this does not arise merely from wear as to thickness of links ; chains harden in use and may snap from this I cause without notice. It is therefore necessary with all chains at leastj once annually to dismantle the same and send them to be annealed. -Yny j THE MACHINE BAKERY AND ITS MANAGEMENT. 629 ordinary smith or engineer’s shop should be able to perform this very neces' sary operation, which is not difficult but requires to be conscientiously done* The rope pulleys must be properly designed to prevent damage to the rope — it is best to obtain them from the engineers who specialise in these hoists ; not only is the shape of groove important, but. also the diameter of pulleys — both must be suitable to ensure a reasonable length of life to the rope. Hoists should be planned so as to reduce the number of rope pulleys employed to a minimum. The hoist is fitted with Stauffer solid grease lubrication, and the same method should be employed for the pulleys. Hoisting Speeds must vary according to circumstances ; 60 ft. per minute is quite sufficiently fast for short lifts, such as from one flour to another, but speads up to 200 ft. per minute may be employed for long lifts. The Hoisting Power varies of course with the speed and weight, but for the average bakery it may be taken that to provide approximately 2-3 h.p. will be sufficient. 725. Flour Storage and Flour Blending. — There can be no doubt that the aeration of flour before use in the bakehouse is beneficial as regards quality of bread produced, and that if it is carried out efficiently and in conjunction with judicious blending of different grades of flour, an advantage can be obtained in regard to quality of the blend over the market price, or inversely a profit be made if a given quality be taken as the standard. To realise these advantages to the full is, however, by no means easy, and involves a great deal of good judgment. It may be taken that the process pays only with considerable outputs or exceptional judgment — or both. Many so-called blending plants are not remunerative, some are even directly harmful. This principally applies where use is largely made of worm conveyors, which are most objectionable because they create dust, due to the friction inseparable from their use. It must be obvious that it is absurd to spoil good flour in this manner after the miller has gone to end- less trouble and expense to eliminate dust and make his flour as granular as possible ! With modern developments of milling, blending has not the importance in an average bakery in this country which once attached to it. The important exceptions are where — 1. The large bakery, properly equipped, specialises in the matter of blending and really deals with the question on scientific lines. 2. The small bakery where the proprietor or manager possesses special knowledge and experience, and by personal good judgment can ensure that it pays him to blend. In all other cases, the millers can be relied upon for supplies of good blends, if judicious selection be made in buying for the requirements of the business. 726. Blending Plant for large Bakery. — ^There is no compromise possible for the large bakery that requires a blending plant. An elaborate and I somewhat expensive installation alone will serve the purpose, and headroom is ! necessary to avoid objectionable conveyors. On Plates XI and XII two cases ! are dealt with. The first shows a plant for storing three blended mixtures i of flour which can then be used at will ; but owing to limited height a conveyor ’is employed for distributing the flour to the storage hoppers. The second ‘ shows the same plant, but so arranged that by the partial raising of the roof ^inclined shoots replace the conveyors. This second arrangement reduces ithe use of conveyors to a minimum ; they are only employed for discharging ^Ithe flour from the hoppers to the automatic weighers, and so do a minimum ^of harm. Flour Blending Plant. Plate XI Flour Blending Plant. Another Arrangement. Plate XII. 631 632 THE TECHNOLOGY OF BREAD-MAKING. A short description of this plant follows : i • r j x The blender is fixed under the floor of the flour store, and is fed from the same It is a “ Pfleiderer ” universal blender, and therefore a batch— and not a continuous— machine. The batch machine is the only one tliat can give a true blend ; continuous machines are only approxiimte and do not give that perfect blending which alone is of real value. The various grades of flour are fed into the blender in predetermined proportions, say four sacks of one, three of a second, and one of a third quality. The machine sifts and aerates the flour as it is fed in. The plant shown would hare an output of about thirty sacks per hour. From the blender the flour is ele- vated to the highest point, and from there descends or is conveyed as thecase may be to one of the three storage hoppers. Valves control the dehr ep as desired. The storage hoppers have a capacity of about eighty sacks each but can of course be varied in size to suit requirements. The stirrers fitted in the base of the hoppers ensure uniform delivery and prevent packing or arching, the final conveyor shoots deliver the flour in a constant stream to the automatic weighers. These discharge into sifters where the flour is finally cleaned and aerated before descending into tiie kneading machines on the first floor. The whole of the gear is operated from the first floor and is handily accessible when using the knead- ers, so far as drawing supplies from the hoppers - is concerned The blend- ing operations and all pertaining thereto are carried out on the third fioor^ In this country, the bread being made during the night, there is no one then on the second or third floors— the blending, hoisting in of the Ao” all attendant operations, are therefore carried out during the day Mhen the bakery proper is not at work. .oinr Photographic views of this plant, showing storage hoppers, eleiator and blender hopper (Fig. 60). blender elevator, automatic weighers, etc. (Fig. Fig. 50 . Flour Blender and storage LioHHjhH. THE MACHINE BAKERY AND ITS MANAGEMENT. 633 Fig. 51 . Flour Elevator and Automatic Weigher. Fig. 52 . Flour Sifter, Kneadeb, and Tempering Tank. 634 THE TECHNOLOGY OF BREAD-MAKING. 51), and sifters, kneaders and tempering tanks (Fig. 52), give a very com- plete idea of the arrangement. 727. Blending Plant for Medium Bakeries— In cases where the cost of the above plant is prohibitive, a very good alternative is to employ the blender only and discharge direct from this into sacks placed on platform scales ; the sacks are then re-hoisted to the upper floor and shot direct into the hopper of the sifter, and thence the flour pursues its usual course into the kneader. As an alternative a smaU blender may be used, with a capacity equal to that of the kneader ; the introduction of an elevator from the blender to the upper floor, arranged to discharge direct into the sifter, then obviates the necessity of sacking and hoisting. In this plant it is obviously neces- sary for each blend to exactly correspond to the size of batch made in the kneader. 728. Blending for SmalllMachine Bakeries. — An excellent plan, which reduces the outlay for machinery to a minimum, is to substitute a hopper Fig. 53. — Special Flour Blending Arrangement. THE MACHINE BAKERY AND ITS MANAGEMENT. 635 feeding direct into the elevator for the blender described in the arrange- ment last mentioned. Pen boards placed in the hopper divide the same into compartments for receiving each one quality of flour. When the hopper is filled the pen boards are withdrawn and the elevator started, caus- ing approximately equal proportions of the various flours forming the blend to be elevated to the sifter. If the kneader is allowed to run for a few moments previous to introducing the liquor, etc., a perfect blend is obtained. Ample time is allowed for obtaining the necessary output per hour of dough if the kneader is of a sufficient size. It will be seen that this arrangement has the further considerable advantage, that an ideal working scheme can be obtained with only two floors. The ground floor will be equipped with ovens, divider, etc., and the first floor with kneader, sifter, and elevator. The first floor therefore serves as doughing-room as w^eU as flour store, and enables the cost of building to be kept at a very reasonable figure. In view of the considerable cost of a fully automatic plant and the relatively small advantage obtained by the use of the same, in comparison with the very simple arrangement last described, the authors recommend the latter except for really large installations. The photographic view (Fig. 53) subjoined, illustrates this arrangement very well. 729. Flour-Sifting [Machinery. — Although many attempts have been made to introduce a sifter with reciprocating sieve or sieves, the rotary machine undoubtedly holds the field and answers all practical requirements. The fact is that the reciprocating sieve, although theoretically the ideal arrangement, is in practice a nuisance because it cannot be made so as to be either noiseless or really durable. On the other hand the rotary sifter is not only quite noiseless and perfectly trustworthy, but from a commercial point of view does its work perfectly. The illustration (Fig. 54) shows a Fig. 54. — Rotary Flour Sifter. machine (similar to that employed in the blending plant, see Fig. 52) with a spiral brush roller working against a semi-circular sieve, which is contained in the lower box- like extension of the machine. The machine is fixed to the underside of the ceiling by bolts through the upper framing, and the half- hinges, which appear on the box-like extension, engage with the other halves, which appear just above the brush roller. The withdrawal of the hinge pins therefore enables the lower half of the sifter to swing open, as shown in the illustration, giving immediate and complete access to the brush roller, sieve and interior of the machine. The bearings of the roller are adjustable, so that wear of the bristles can be compensated for, and are fitted with ■636 THE TECHNOLOGY OF BREAD-MAKING. Stauffer solid grease lubricators. The spout on the right-hand side serves for discharging the tailings, and a canvas bag should be kept tied to this, to receive the same ; it should be emptied daily and replaced ready for the next day’s work. The same machine is supplied fitted with a fiy- wheel and chain drive for use in bakeries not employing mechanical power (see paragraph 695 and following). In some cases this sifter is also fitted on the kneading machine itself, in which case its construction dispenses entirely with wood, except for the roller. Reference to Fig. 62 will show' this arrangement. 730. Tempering and Measuring Water. — ^The introduction of machinery in general, and of automatic bread-making plants in particular, calls for more accurate methods in the bakery than were formerly considered neces- sary. So long as doughs were made by hand the operative was more or less a craftsman, who could judge by touch and appearance as to whether the dough was of the correct consistency or not. The craftsmen are getting fewer every year, and in any case cannot be relied upon for sufficiently accurate judgment to suit modern requirements. In addition, however sldlful the workman, he has in modern machinery no opportunity of con- trolling the consistency of his dough, other than by accurately weighing and measuring the materials ; therefore if bread is to be satisfactory and uniform, if automatic dividers, provers, and moulders, are to yield the best results, and ovens are to soak the bread properly in a given number of minutes at a predetermined temperature, it follows that the doughs must be perfectly uniform. If they are not so, the results are either not of the best, or the smooth working of the bakery must be disturbed by allowing batches to have different periods for proving and baking. Clearly, then, too much care cannot be exer- cised in the making of dough. This subject will subsequently receive further consideration (see paragraphs 731-4) ; it is sufficient for the present pur- pose to say that an appliance is necessary, which will enable an exact quantity of water at a pre-arranged temperature to be accurately and readily ob- tained. Needless to say, the arrangements should also be such as to enable this result to be obtained without unneces- sary waste of water in adjust- ing the temperature desired. Theoretically, much might be said in favour of w'eighing the water, as the most accurate way to obtain a given quantity. In practice, appliances for weighing introduce many com- plications of an undesirable nature, and are liable to de- rangement, leading to greater inaccuracies than simpler ap- paratus involves. The best Measuring Tank, and most practical arrangement Fig. 55. — Tempering and THE MACHINE BAKERY AND ITS MANAGEMENT. 637 is the tempering or attemperating and measuring tank here illustrated (Fig. 55). It is a tank formed of steel sheets, tinned inside, and supported on the wall adjacent to the kneader, or on the latter itself. Hot and cold water are conveyed thereto in large bore pipes to prevent delay. The hot- water pipe is internally taken to the bottom of the tank, and the cold- water pipe discharges at the top. Thus an excellent mixing is obtained by the aid of natural laws, but, as an extra, a mixing paddle can be fixed with a vertical spindle — this hastens and perfects the process of obtaining a tank full of water at a uniform temperature, as ascertained by a thermo- meter which is immersed, completely and readily visible through the plate- glass front of the tank. An internal overflow pipe is fitted and wherever possible (in all new bakeries, for instance) a sink or gully should be provided immediately below the position which a tank is to occupy. This gully will not only take such overflow from the tank as occurs, but is useful for washing down the floor, the kneader, and for emptying pails, etc. The specially useful feature about the tank illustrated is the sliding scale (Williams’ patent) seen through the glass front, and readily raised and lowered by means of the hand- wheel on the left. This scale is plainly marked in gallons, as seen in the illustra- tion, and facilitates the drawing off of the exact quantity of water required. In any ordinary tank it is practically impossible to obtain a pre-arranged level of the water, while tempering the same to say 96° F., without per- mitting an overflow, and thereby incurring a waste of water. The tank illustrated, however, is larger than the maximum capacity registered on the scale, and therefore allows sufficient margin for obtaining the correct degree of heat without overflow or waste. As soon as the water is at the right temperature and thoroughly mixed, which is indicated by the thermometer reading remaining stationary, the scale is moved to the position in which the zero mark exactly corresponds to the level of the water. The universally- jointed pipe, shown in an upright position in the illustration, is next placed in position to discharge the water into the kneader, and then the large draw- off shown is opened. As the water runs out of the tank and the level sinks, it is clear that the cock merely requires to be closed sharply when the water level has sunk to the mark indicating the desired number of gallons, to ensure that the right quantity of water, at the correct temperature, has been delivered into the kneader. These tanks are made in various sizes to corre- spond to the capacity of the kneader. Attention is here drawn to the fact that certain waters (notably some moor waters) corrode iron and steel, even when protected by galvanising. To meet such cases these tanks are also made of copper and gun-metal throughout, coated with tin internally. These tanks are so cleanly and useful in saving time and ensuring better and more uniform results, that their employment, even in hand-w'orked bakeries, must be recommended. It is quite a common error to suppose that they are useful only in connec- tion with machinery. 731. Dough Mixers and Kneading Machines. — Of modem dough-making machines there are three principal types which require to be considered in detail and which practically cover the entire field. The first group em- braces machines constructed upon the principle of a revolving drum, the second employs a stationary trough with blades revolving around their ow n axes, and the third, arms moving in fixed planes in a revolving pan. 732. Rotary Mixers. — The idea underlying a rotary mixer is extremely simple. A drum, of a volume considerably greater than the size of the batch to be made, is revolved around a horizontal axle, wliich runs through the drum. Parallel to the axle are placed a number of metal rods which 638 THE TECHNOLOGY OF BREAD-MAKING. pass from one side of tlie drum to the other. A square opening is cut in the cylindrical sheet, which forms the drum and joins up the two circular cast- ings, which constitute the sides ; the opening is closed by a removable door. In revolving, the flour, water, etc., are tumbled about and over the bars until the dough is made. The door is then removed and the drum is revolved, until the opening is at the lowest point and the dough allowed to discharge itself. It will be seen that the machine is of a simple nature, does not require much power, and can be made very cheaply. But there its advantages end, and it is necessary to say that while its simplicity and inexpensiveness are attractive, the dough it makes is not kneaded at all in the proper sense, and lacks texture, volume and colour, while being wet, sticky and inclined to be lumpy when discharged. It follows that while the machine may answer for slack doughs, it cannot be recommended for those of a stiffer nature or for high-class work, or for obtaining a maximum yield. An impartial trial, with precisely similar flour and other types of machine, will prove this. The rotary kneader was first put upon the market under the “ Adair patents. 733. Kneading Machines with Revolving Blades. — ^The construction of these machines is based upon the employment of a cylindrical trough which encases a revolving blade, with the axes of the two coinciding. The sheet which forms the trough does not ^complete the circumference, but merges above into a rectangular hopper, open at the top. In most machines two cylinders are employed with parallel axes, apart from one another by a distance rather less than the diameter of each cylinder. In exceptional cases three blades are employed, but the arrangement introduces undesirable complications and possesses no advantages per se. In the earliest machines, and]many others, the blades were of a haphazard and of a more or less fanciful design, and although they all made and make dough, yet the problem of the shape of the blades does not seem to have been worked out on scientific lines. The Two - hladed Kneader may be safely considered the most typ- ical and widely - used dough-making machine employed in bakeries, and as such requires to be dealt with more fully. The best example of these is that known as the “Universal’' (Pfleiderer’s patent). In its original form, this was the first machine to be efficiently manufactured and intro- duced to the bakery trade. It is also generally acknowledged to be the most successful,excepting only for certain special types of dough. Of this machine an illustration is Fio. 5(i. “I’NIVKRSAL” Kneaihng Machink, given in Fig. 56, showing PrLEi])p:RER’s Patient. the machine nearly tilted [ THE MACHINE BAKERY AND ITS MANAGEMENT. 639 over for discharging the dough. The main secret of the success of this machine lies in the form of the blades, which are constructed on highly scientific lines, and ensure that every particle of the contents of the trough is brought within their action with absolute thoroughness. A small model machine on the same lines is sold by the makers, which constitutes a most useful addition to laboratories generally, where it is invaluable in many ways, apart from its utility as adough-maker for small test batches. This little machine demonstrates the perfect mixing action very effectively, if it be charged with dry flour, and a pinch of red lead. With a stated num- ber of revolutions it will so thoroughly incorporate the two ingredients, which by other means are not at all easy to mix intimately on account of the great difference in specific gravity, that a small part of the mixture, jDlaced on a sheet of paper, will successfully stand the severe test of being “ smeared with a palette knife to prove the uniformity of mixing obtained. Returning to the dough kneader, the next point to be mentioned lies in the arrangements for preventing the escape of liquid from the trough and for making the entering of grease or dirt impossible. The problem is not an easy one, but has been solved very simply and effectively. There are only six bearings in this machine, apart from the tw^o loose pulleys in connec- tion with the driving gear, and all are fitted with Stauffer solid grease lubri- cators. The drive is arranged to be reversible by means of friction clutches formed between each of the two pulleys and the central driving disc, which is enlarged in diameter and fitted with a handy rim to enable the machine to be pulled round by hand when being cleaned. The control is from the hand- wheel overhanging the pulleys, which are driven in opposite directions Fig. 58 . “Universal” Kneading Machine, Single Blade, Fitted with Electric Motor. by belts from the line shaft, one “ open and one “ crossed,^’ thus enabling the blades to be driven in either direction. The weight of the trough is balanced by counterweights, and the raising or lowering may be by hand or power as desired. The interior of the trough as well as the surface of the 640 THE TECHNOLOGY OF BREAD-MAKING. blades are ground and polished, and the dough leaves these surfaces per- fectly clean, on being turned out, except with very slack doughs. The machine is fitted, if desired, for driving direct by electric motor,, which is then supplied with a reversing controller to enable the machine to be reversed. Fig. 58 shows a single-blade “ Universal fitted with a motor direct. This machine is made with pulley drive also, or the machine shown in Fig. 56 can also be fitted, self-contained, with electric motor as. here shown (Fig. 59). To prevent the raising of flour dust, which would Fig. 59. — “Universal” Kneading Machine fitted with Electric Motor. result from working the machines without a lid, these kneaders are either fitted as shown in Fig. 52 and connected direct to the sifter, or they can be supplied with a “ safety '' lid, which is so interlocked with the driving gear that it is impossible to raise the lid while the machine is in operation. In certain countries these “ safety '' lids are made compulsory, as a preven- tion for accidents to operatives. With regard to the dough made by these machines, it may be said that it is of a very high quality, perfectly uniform, and, if not overworked, far better than can be obtained by hand under commercial conditions. Hy- gienically also the machine is perfect, as it lends itself readily to being cleaned with great thoroughness, and no contamination of the dough can occur. As to durability, a subject on which it is only possible to speak authorita- tively after many years, there are machines still in hardest everyday use which were installed from twenty-six to thirty years ago, and no renewals of a serious nature, or repairs, have been necessary in this long time. 734. Kneaders with Rotating Pans. — These are a comparatively modern product ; many are of too light a construction to be serviceable, and have the .serious defect that working parts requiring lubrication are to be found over the dough, on which grounds their use cannot be recommended. These machines employ a different principle altogether to those already described, and rely upon the stickiness and plastic and tenacious qualities of dough for tlieir action, which may perhaps be described as more akin to sugar “ pulling than anything else. THE MACHINE BAKERY AND ITS MANAGEMENT. 641 Fig. 61 shows a diagram of the ‘‘ Viennara kneader (“ Poin ton's '' patent). The arm is fitted with double horns, as shown in Figs. 62 and Fig. 61. “Viennara” Kneading Machine. Sectional Diagram. Ip ii j-rm— j— TT^a 63, and describes a curve, which compels the horns to move in a path shown in dotted lines (Fig. 61). The gearing is so arranged that the speed throughout this curve is not constant ; it is slowest when the horns are descending and increases rapidly as the horns sweep the radius between the bottom and side of the pan, being at its greatest during the upward movement. The pan slowly revolves (about 4J revolutions per minute), and being filled with flour to the line indicated, brings fresh material under the influence of the arm at each stroke (26 per minute). The effect is to subject the dough, when incorporated, to a combined aerating stretch- ing and folding action, most admirably adapted to develop it under ideal conditions and to an extent quite impossible by manual labour. The operation of the arm is of the gentlest kind, and owing to the perfectly combined aerating folding and stretching which the dough receives, it is of a remarkably fine texture, toughness, colour, and volume. Many claims have been made for devices for increasing the yield, a point on which bakers have become rightly sceptical ; but certainly the “ Viennara " has remark- able properties in the direction of causing the flour to absorb its proper proportion of water without loss of stiffness or elasticity. Consequently, the dough produced shows a decided improvement in colour. Fig. 62 shows the complete machine with sifter and tempering tank self-contained. As will be seen, a door is fitted in the pan, which can only be stopped in the correct position for discharging. This door is interlocked T T 642 THE TECHNOLOGY OF BREAD-MAKING. with the driving control in such a manner as to make any mistake impossible. The dough truck runs under the pan, and the dough is discharged automatic- ally by the arm alone being worked, while the pan remains stationary. The domed lid is a fixture, but the front portion is hinged and can be raised so that the dough can be inspected. The pan, having no blades, bearings or axles, has a perfectly smooth interior ; it is therefore hygienically perfect and practically keeps itself clean. The door gives no trouble from leakage or any other cause. The power required for the machine is very little and not more than one-half that absorbed by the “ Universal.’" Fig. 62 . “Viennara” Kneading Machine. Another form of this machine is that illustrated in Fig. 63, and known as the “ Kempter ” patent. The general principle is exactly the same as that described above, the essential difference being that whereas the machine first described has a pan which is an integral part of the machine, the Kempter modification is fitted with a removable pan. The idea is to use the pans as THE MACHINE BAKERY AND ITS MANAGEMENT. 643 dough trucks, and as all are interchangeable, one machine serves for them all. One advantage is that for “ cutting back the pans are simply brought back to the machine, which does the work admirably. This type is used more especially on the Continent, whereas the self-discharging machine has found preference in this country. The dough made is of equal excellence in either. Fig. 63 . Kneading Machine, Kempter Patent. In conclusion two important subsidiary advantages in the “ Viennara machine must be referred to. The first is that owing to the extremely gentle action of the machine, the arm of wdiich can in no wise damage the dough more than a man’s arm does in kneading, it is practically impossible to overwork a batch. Men will leave their jobs and cannot be relied upon to do exactly as they are told ; it is therefore distinctly an advantage in this machine that by being left longer at work than is necessary it cannot damage 644 THE TECHNOLOGY OF BREAD-MAKING. — but will, in fact, rather improve, the dough. The second point needing a special reference is that, unlike other machines, this is a very safe appliance, in using which it is scarcely possible for a man to receive injury. The arm on its upward stroke will push out a man’s hand, and can never pull him in if he attempts to feel the dough, as is only too frequently done. 735. Sponge-making Machines. — Before leaving the subject of kneaders it is necessary to describe the application of such machines to the making of “ sponges.” Although the tendency in machine bakeries has been for many years to adopt the “ straight dough ” system, dispensing with sponges and kneading the flour with yeast and salt into a dough direct, yet the older process holds its own in many countries, and also in portions of the United Kingdom, notably in Scotland and Ireland. A very convenient combina- tion is provided by the “ Universal ” machine already described, when such a machine is fitted with two speeds to be used at will. It will be clear that this enables a high speed action to be used for making light sponges, which when made are turned out into dough trucks and left to prove. These sponges when ready are then utilised for making the dough, for which the second or normal slow speed of the kneader is used. 736. Sponge-Stirrer. — Another form of machine frequently used is the sponge-stirrer, of which an illustration is given in Fig. 64, A cast-iron Fig. 64 . Sponge- Stirring Machines. standard carries the driving gear as well as the upright spindle fitted with suitable blades, which being balanced and arranged to be conveniently raised, permits the tub, fitted with castors, to be readily placed in position. The sliding casting, shown in the illustration above the stirrer proper, rises and fallsVith the latter, and acts as a self-centring guide to the tub, which THE MACHINE BAKERY AND ITS MANAGEMENT. 645 is automatically locked in position as soon as the spindle lias been lowered. A sifter is fixed above the stirrer (as shown) and, by means of a canvas shoot enables the flour to pass direct into the tub. The illustration also shows the kneader, with sifter and tempering tank and the tub lift, with a tub lifted ready for discharging its contents into the kneader, thus giving a very clear idea of the whole installation for suitably dealing with doughs in such bakeries as employ the “ sponging '' process. 737. Dough Trucks and Dough Proving. — As has been already pointed out in paragraphs 683 and 696 dough trucks should always be movable. They should therefore be of a “ handy ” size, never exceeding a capacity for two sacks. They should be fitted with castors, or if preferred with one castor at each end and an axle in the centre, with two loose wheels, designed to take the whole load and keep the castors just off the floor. In this country the dough trucks are almost universally of wood. It is difficult to account for the prejudice, which tenaciously clings to British practice, against the employment of metal in this connection, despite the fact that Fig. 65 . Steel Dough Truck. in all other matters pertaining to bakery equipment, especially as regards large establishments, this country is undoubtedly ahead of all others. The common idea is that the metal trough must chill the dough, but as the dough will be chilled in any case if the bakehouse is cold — and the truck cannot be cold if the bakery is not — the conclusion is not very logical. Further, the specific heat of iron is low, and the trough cannot under any ordinary circum- stances, affect the temperature of the dough to a material extent. As a matter of fact the wooden dough truck has practically disappeared from all modern plants on the Continent, and as the Continental baker appreciates the importance of not chilling his dough, at least as much as his British con- frere, the statement that there is no objection to the use of iron or steel in dough trucks, any more than in kneaders, dividers or moulders, must be held to be proved correct. Of course every baker will please his own tastes in such a matter as this, but it is at least worth while to point out that the 646 THE TECHNOLOGY OF BREAD-MAKING. not inconsiderable wear and tear, with consequent renewals, occasioned by the use of wooden trucks, may be eliminated by the employment of the very much more hygienic and durable steel truck, with bright ground interior surface, similar to that of a kneader. A good plan is to use steel troughs tinned inside, as being the most suitable surface. An illustration (Fig. 65) is given of such a trough showing its general construction. The dimensions of trucks should be suitable for the machines with which they are to be used, a point sometimes overlooked, and both width and depth should not be too great, as unduly heavy work is otherwise thrown upon the operative. Inside dimensions of about 2 ft. in width and 1 ft. 6 in. in depth should not be exceeded. 738. Proving-Rooms. — When bread was almost universally made by the long sponge system, the employment of separate rooms, kept at an even temperature, for the storage of sponges during fermentation, was always regarded as a great advantage. With the advent of automatic plants, the subject requires consideration in a new light. The fact is that separate proving-rooms may be responsible for bad results, where automatic plants are in use, unless steps are taken to ensure that the temperature of such rooms does not vary from that of the machines. Now it cannot be suffi- ciently insisted upon that dough must not be subjected to changes of tem- perature throughout its different phases ; and, when ready for dividing (scaling), should not be brought into rooms, or fed into machines, which are at a different temperature than the dough itself. It follows that the arrangement of the bakery should be such as to make this automatic if possible, because the more it is left to the men to observe such matters and regulate temperatures the more trouble will ensue. The machine-room, and therefore the machines contained therein, should be kept at a uniform temperature, equal to that of the doughing and proving-room, and all should of course be arranged so that they are free from draughts. If this cardinal principle is adopted and never lost sight of, and if new bakeries are designed with this clearly in view, much trouble and constant watching will be saved. Assuming a bakery perfect in this respect and equipped with automatic plant of the best type, a wonderfully high and uniform standard of bread will be obtained, if reasonable care be used in preparing the doughs at the proper and uniform temperature. 739. Dough Dividers. — ^These were first placed upon the market in a commercially practicable form about the year 1896. The introduction of loaf dough-dividing machinery marks a distinct and very far-reaching development in the mechanical equipment of bakeries. All subsequent stages of dough-making and machine- working, however difficult of solution in themselves, are dependent upon, and secondary to, the problem of satis- factorily weighing off pieces of dough of given weights from the bulk. In the course of the last fifteen years three main principles have been employed in the construction of dividers. Cylinders or boxes with close-fitting rams, the latter adjustable to give variable volumes provided to receive the dough necessary to form one piece or loaf, are common to all three types referred to. It is in the means employed for charging these cylinders or boxes with dough that the three types principally and materially differ. A worm, acting as a conveyor at the base of a dough hopper — fluted or roughened rollers running in opposite directions, charging a chamber, communicating with the cylinders — and a weighted ram acting upon the dough confined in a closed chamber, are the three different means referred to. All three prin- ciples lend themselves to the construction of machines capable of cutting dough pieces, with sufficient accuracy for all commercial purposes ; in fact to the production of loaves of much more uniform and accurate weight THE MACHINE BAKERY AND ITS MANAGEMENT. 647 than is commercially obtainable by hand. The effect of such machines upon the dough, and upon the process of fermentation, is, however, the chief consideration and requires to be most carefully taken into account. Dough is not a material which may be ill-treated with impunity ; it is, or should be, a living mass which may suffer irretrievable damage if handled with a trifling excess over the permissible severity. This aspect of the matter is often dismissed with unpardonable levity, on the plea that “ a little more yeast will soon put that right,'’ or that “ it can be left a little longer to recover ” ! There is no such thing as artificially counteracting actual damage, either by an extra allowance of yeast or reviving fermentation. Fig. 66. Two-Cylinder Dough Dividing Machine. which has unduly suffered, by allowing extra proof. These are palhatives and may mend, to some extent, the worst effects of undue severity, but cannot and do not allow a healthy growth or perfect development to take place. 648 THE TECHNOLOGY OF BREAD-MAKING. In two of the systems quoted above there is the inherent drawback that the force put into the dough (or force with which the dough is handled) cannot be definitely hmited in such a manner as to preclude damage. The action is not positive, and therefore always employs a surplus of feeding capacity to ensure the filling of the cylinders, which by their regulated volume give the weights required. On the other hand, the third type absolutely limits the force employed and is positive in its action. The pressure to which the dough is subjected by the ram which causes it to enter the division boxes can never exceed a safe and predetermined maximum, since it is due to a weight which in working remains constant but can be varied to suit the requirements of the class of dough used, and never forces forw^ard a greater quantity than the measuring cylinders absorb. It follows that the maximum advantage, when using a machine of this type, will ^be obtained by employing a minimum weight to give sufficiently accurate loaves. Fig. 67. Larger Dough Dividing Machine. Correct Weights . — It will be opportune, at this point, to call attention to the relative value of weighings, more or less accurate. It is a fact that it is possible to insist upon too much accuracy, especially in view of the very natural tendency to scale as closely as possible and obtain the maximum saving in dough. Everything, however, may be carried to excess, and a baker may easily lose more in quality, and therefore in texture, bulk, and general attractiveness of loaf, than he gains in dough by very close weighing. Extreme accuracy is inseparable from punishment, and in turn punish- ment is inseparable from loss in legitimate selling qualities of the loaf. So long as a divider gives more accurate weighings than can be commercially obtained by hand-scaling, a business will be more benefited by good quality. THE MACHINE BAKERY AND ITS MANAGEMENT. 649 due to avoidance of punishment, than from an insistence on the maximum economy in dough. The sound plan therefore is to choose the divider which is limited in its punishing effects, and then adjust the machine to work with the minimum weight required to ensure sufficient accuracy for commercial purposes. The illustration (Fig. 66) shows a two -cylinder deadweight divider, suitable for small bakeries, which has a maximum output of 1,400 pieces per hour. For guidance as to the proper proportioning of output, remunerative- ness, etc., see paragraphs 697 and 699. A larger machine with outputs up to 2,400 pieces per hour is sliovTi in Fig. 67 and referred to in paragraph 746 under Automatic Plants. Both machines are made right and left handed for belt, or direct electrical, driving. 740. Moulding Machines. — When the newly-kneaded dough is turned out into the dough truck, it requires to be left undisturbed at a proper temperature in order to ferment, and as a result of the generation of gases the original volume of the dough is much increased. It is here that the value of a good kneading machine becomes apparent, because if thorough aeration has been combined with a maximum of stretching and folding, the result will be a dough which excels in bulk, toughness, fineness of texture, and good colour. To obtain the best results it is essential for the development of fermenta- tion to be as uniform throughout the whole mass of dough as possible, and for the gluten to be toughened, so as to resist the gases uniformly, causing an evenness and silkiness of texture not otherwise obtainable. Judicious and efficient “cutting back’" assists uniformity for the same reason,^ and when finally ready for scaling or dividing a good dough must be uniform all over. It will be apparent that in cutting the dough, when scaling or dividing into pieces of a size suitable for loaves, these conditions are disturbed, inas- much as fermentation will, from that moment, take place under totally different circumstances. Apart from this, the cutting produces wounds, which form portions of the surfaces of the piece intended to become a loaf. It is therefore necessary to re-work each piece, with the two-fold object of closing the wound by forming a complete skin all over the dough- piece, and of working the interior, so as to cause fermentation to continue under conditions which will be uniform and suitable throughout the newly detached piece of dough intended to become a loaf. This process is called moulding. Hand Moulding has hitherto been performed in such a manner that the piece was rolled on a table, against the palm of the hand, as a more or less pear-shaped mass, causing the central portions to be worked outwards, and vice versa. It was essential to preserve the skin, which was formed in this process, from rupture while tightening up the interior, which of course had the effect of stretching the skin simultaneously. The tail of the loaf, similar to the gradually contracting and tube-like lower extremity of an inflated balloon, sealed the skin and was worked into the loaf -piece at the conclusion of the operation, when each piece should become as nearly spherical as possible. The loaf was placed tail downwards on boards or in drawers to undergo a further period of proving, protected from chills. It is needless to say that good moulding could only be performed by a craftsman, and that the quality of workmanship varied to a very great extent. The labour was monoton- ous, and also arduous, if carried on indefinitely, while effective supervision and a maximum speed were not easily obtained. From a hygienic point of view also it was objectionable. Machine Moulding . — To find a satisfactory solution of the difficult problem of moulding dough by mechanical methods proved by no means 650 THE TECHNOLOGY OF BREAD-MAKING. easy. The experience of several years’ working, however, conclusively shows that the task has been accomplished. The principle adopted is to impart to the dough-piece a continuous, rotatory, and screw-like motion (“ Poin- ton’s ” patent) by feeding it into a spirally shaped trough arranged upon a revolving cone-shaped table (see Fig. 68). Fig. 68. Dough Moulding Machine. The spiral trough is stationary, with its finished (ground) surface on its under or working side ; it is supported by arm-rods, and brackets from above by means of the column, around which the table revolves. The table is grooved to afford grip to the dough. It is obvious that if the trough were merely arranged to encircle the table horizontally a pure rolling motion would be imparted to the loaf. A skin might thus be formed, although it would be wrinkled and not in any way stretched, but the dough itself would only be squeezed about and in no sense truly moulded. The illustration, however, shows that the trough, after a short horizontal length, to enable the dough-piece to start rolling, gradually ascends the cone table, causing the loaf to be forced against it. The result is that the dough-mass does, in fact, undergo a screw-like motion, systematically displacing and methodically rearranging the whole of its bulk, while stretching the skin continuously from the head of the loaf tailwards in every direction. At its upper or delivery end the trough again “ eases off ” its rate of mounting the conical table, and thus ceases to form the tail, which is “ tucked in,” and enables the finished loaf to roll off the table in as nearly a spherical con- THE MACHINE BAKERY AND ITS MANAGEMENT. 651 dition as is necessary for all practical purposes. The proper accomplish- ment of this process is essential to the obtainment of “ build” ensuring not only a tough and highly stretched skin and a thoroughly worked interior to the loaf, but also that orderly and regular rearrangement of the cellular structure which, by means of proper subsequent proving, compels the growth of that much desired and beautiful texture of the perfectly developed loaf of bread. From the description given, it will be seen that the “ pitch of the trough, which governs the rate at which it ascends the table, will regulate the degree of “ working imparted to the dough. If too much “ working ’’ is put into the dough, the skin of the loaf will be overstretched and yield under the strain ; and if too little, then the “ build will not be sufficient. It is neces- sary also to point out that the capacity of the trough must be suitable Fig. 69 . Flexible Moulding Machine. approximately to the size of the loaf to be moulded. In consequence of these two important considerations a number of troughs are required for each such moulder, if various sizes of loaves — or if bread made from doughs of widely differing consistency — are required to be moulded. In practice the cone-table or “ umbrella moulder is now only employed in businesses with uniform outputs. 741. Flexible Moulder. — In order to provide a moulder which shall be capable of ready and instantaneous adaptation to all the varying require- ments of average bakeries, the inventors of the previously-described machine have recently put upon the market an improved and perfected form, illus- trated in Fig. 69, which they term the flexible moulder. The principle underlying the construction of this machine is exactly the same as that of the “ umbrella '' type. A flat moving table is formed by close-fitting metal laths connected by chains which constitutes an endless iron belt running over axles, whose axes are steeply inclined from the horizontal. The moulding 652 THE TECHNOLOGY OF BREAD-MAKING. troughs are thus enabled to be made perfectly straight and therefore adjust- able for capacity by the simple and instantaneous movement of a single lever ; they can consequently mould dough-pieces of widely differing weights, found in practice to vary from J lb. to 4 lb. pieces. Being suitably supported by bridges spanning the entire width of the moulding surface, the angularity of the troughs upon the table can also be adjusted at will, so that doughs of widely differing consistencies can be dealt with. This machine is provided with the following fittings — two parallel troughs, a “ splitter,'’ which cuts the 2 lb. piece of dough into suitably proportioned pieces for forming the “ tops " and “ bottoms " of cottage loaves, and a tin shaper for suitably shaping tin loaves to fit the particular “ pans " in use. It may therefore be fairly claimed for this machine that it is universal in its scope, and solves all the requirements connected with the “ balling up ” type of moulding. 742, Quality of Machine-Moulding. — It is perhaps natural that sceptic- ism should be felt in regard to the degree of good workmanship attainable by such machinery as has been described, when the difficulty of getting good moulding by hand is borne in mind. Flexible moulders are of such recent introduction that the number of bakers who have as yet had the opportunity of seeing such machines at work is comparatively limited. For the guidance of those who may remain unconvinced, the authors’ per- sonal experience is that the machine above described will mould as well as the journeyman, with this important point in its favour — that it reaches the same standard of perfection with every single one of the 3,000 loaves which it is capable of turning out per hour. The journeyman’s average workmanship will be much below the best he can do, but the flexible moulder will never fall below its best. Hence, moulding machinery should be care- fully investigated on behalf of every progressive machine bakery. , 743. Handing-Up and Proving. — If a loaf is moulded directly after having been scaled off it will lack development and cannot possibly be either of as good texture or bulk as it should be. It is therefore necessary to give each dough-piece a preliminary moulding after being scaled off, so that it may have a period of rest in which to recover or prove before being finally moulded into shape ready for baking. This preliminary process is called “ handing-up ” or “ balling-up.” The above remarks apply to ordinary hand-made bread, notwithstanding the fact that there are a good many bakeries, especially in certain districts, where the loaf is finally moulded directly after having been scaled or divided. When considering the ques- tion of machine-moulding, it is very necessary to appreciate accurately the different conditions under which the dough is then handled. When hand- moulding is employed there is always a considerable number of dough -pieces on the table which have been scaled or divided ; which means that there is always a short period of rest before moulding actually takes place. Slight as this rest may be, it is essential, and gives the dough an opportunity of recovery before being moulded. This it cannot possibly have if fed auto- matically from a divider into a moulder, as under such conditions the mould- ing takes place the instant the piece has been divided. In hand-w^orking there is no reason why this accumulation of loaves and consequent rest should not be allowed to take place, as it involves no extra labour and is beneficial to the dough. With machinery, however, unless the divider feeds directly into the moulder, an additional man would be required to feed into that machine. The necessity for handing-up, although ahvays present if a good loaf is required, is all the more pronounced in the case of machinery; excepting only in special cases such as with very slack tin doughs, which may go direct from the divider to the moulder with reasonably satisfactory results. It w'ill be understood, how^ever, that these remarks apply only to THE MACHINE BAKERY AND ITS MANAGEMENT. 653 cases in which the aim is only an average quality of workmanship ; there can be no doubt that, where a really good loaf is desired, handing-up is indispensable and remunerative. Assuming then that handing-up must be included as an essential operation in the process of making a good loaf, it becomes necessary, for businesses with an output sufficiently large to necessi- tate continuous running of machines during working hours, to instal two moulding machines for every divider. 744. Hander-Up. — The first of these machines is coupled direct to the divider and is called a hander-up. In principle, the hander-up is exactly similar to the moulder ; but as the newly divided loaf is of smaller bulk than when it comes to be finally moulded and also requires less action put into it, the hander-up is a smaller machine than the finishing moulder. Businesses with outputs up to one-half the capacity of the divider installed, "need not instal two moulders, but by employing a finishing moulder only may, by arranging for the machines to be worked inter- mittently, get as good and as economical work as the full equipment yields to the business with a large output. In either event, that is to say whether handing-up and moulding are done in separate machines or on a finish- ing moulder only, a period of rest, averaging about 20 minutes, is necessary between the two operations, and provision has to be made for proving the loaves under suitable conditions as to temperature and protection from draughts. To use any of the older devices in this connection, such as drawers or proving racks, etc., entails the separate handling of each loaf into and out of the accommodation provided, apart from the labour in feeding the loaves into the final moulder. It also involves possibilities of bad organisation and careless marshalling of the racks, while the men may not take the batches in their proper consecutive order and may thus give some less and others more than their proper period of proof. Consider- able space for racks, etc., and for moving them about would be required. 745. Automatic Prover. — To obviate the foregoing objections and dis- pense with all labour between the hander-up and moulder, and ensure the best possible development of the loaf, the automatic prover has been intro- duced. This machine receives the loaves from the hander-up, and dis- charges them, fully proved, in perfect condition to the moulder ; the whole process, from the feeding of the divider to the discharge of the finished loaf ready for the oven, thereby becomes perfectly automatic. The auto prover (“ Pointon’s ” patent) is essentially a conveyor suitably regulated as to speed (with provision to vary the latter if required and thoroughly enclosed to exclude draughts. Further, it is capable of being heated, and in any event is supplied with moist vapour so as to prevent a dry skin from forming on the loaves, which are consequently proved under perfect conditions. 746. Auto-Dividing, Proving, and Moulding Plant. — Fig. 70 shows dia- grammatic representations of ,two modifications of an entire plant of this description, and Fig. 71 a photographic view of the upper one. The loaves coming from the divider fall direct into troughs on the hander-up and, having been “ balled up,"’ are deposited on trays (eight pieces on each tray, in the full size machine), which are carried on chains, traversing the interior of the prover by a circuitous course in such a manner as to effect as great a saving of floor space as height of ceiling and other circumstances permit. The trays move intermittently, and of course at a speed suitable to give the length of proof required, which normally is from 15 to 20 minutes. Stepped pulleys are provided for running these trays, so that the rate of speed can be controlled within certain limits. By the time a tray has 654 THE TECHNOLOGY OF BREAD-MAKING. Fig. 70 . Diagrams of Automatic Plants. THE MACHINE BAKERY AND ITS MANAGEMENT. 655 travelled round the prover and has allowed the loaves deposited upon it from the hander-up to undergo the correct period of proof, it reaches a position directly over the delivery band and by engaging with a suitable gear is turned upside down, depositing its load of eight loaves on the delivery band. The latter, travelling out sideways, delivers the loaves singly on to a further conveyor which feeds them (in the case of cottage loaves through the splitter already referred to) into the finishing moulder. The lower diagram in Fig. 70 shows a form of prover in which much greater variations in length of proof can be obtained at will. By con- venient mechanical arrangements the long conveying band can be “short circuited ” at desired points and the loaves at once passed direct to the finishing moulder. The prover is so designed that it can be arranged in a variety of ways in order to suit varying local conditions. It normally occupies a fioor space of Fig. 71. View of Automatic Plant. about 12 ft. X 10 ft., but can be suspended under the ceiling to partly over- hang the moulder ; or it may be fixed, together with the hander-up and divider, on an upper floor and deliver to the moulder below. The best arrangement, however, to suit any given place must of necessity be decided in consultation with the engineers. On the face of matters it might be thought that a prover arranged under the ceiling would be best with a view to the saving of floor space thus effected, but as a matter of fact there are a number of serious objections to this plan, which should only be adopted if exigencies of space compel this course. Every one, with experience of bakery working, well knows the difficulty of ensuring cleanliness in odd corners and inaccessible places. A prover, with its damp heat, is peculiarly liable to get into an insanitary condition, and thus calls for rigid cleanliness and scrupulous attention. .Being, therefore, of all the machines employed in the bakery to-day the one most needing conscientious inspection, it is the last which should be so placed as to render efficient daily examination diffi- cult. 656 THE TECHNOLOGY OF BREAD-MAKING. The prover, illustrated and described, thoroughly meets these require- ments ; it is fitted with large doors, so that it can be opened out every day, and thoroughly ventilated. Readily removable cloths are fitted to the trays, so that their frequent washing is facilitated. A permanently fitted light in the interior is recommended, so that it may be impossible for any part of it to get into an unhygienic and objectionable condition without instant detection. The whole of the trays in the prover can be easily removed (they are only hung upon pegs) and should be periodically scrubbed. V^Tien the trays are removed, the interior of the prover can be entered and examined without difficulty — the reader may imagine himself standing in it, as in a small room. The result of five or six years’ continuous working, in actual bakehouse use, is entirely satisfactory ; it may therefore be safely stated that the apparatus is now entirely beyond the experimental stage. The prover is really free from any wear and tear, as the speed of the running parts is low, and the load on the trays is practically balanced. Fig. 72 . Semi-Automatic Plant. The power required for driving the complete installation, consisting of dough divider, hander-up, auto prover and finishing moulder, is only about 8 h.p. The plant, when once installed, is therefore not expensive to run, since the whole of the operations indicated are carried out with one man for feeding the dough into the divider. When the dough has been thus fed, a maximum output of finished loaves from the moulder is obtained at the rate of 2,400 pieces per hour. For bakeries requiring intermittent working a semi-auto plant is available, of which a view is shown in Fig. 72. 747. “ Setters.” — The appliances hitherto in use in modern bakeries for receiving the moulded loaves, and for conveying them to the ovens, in so far as they have been specially adapted at all, have all been modifications THE MACHINE BAKERY AND ITS MANAGEMENT. 657 more or less of the type introduced in the early days of drawplate ovens under “ Price’s ” patent. An upright framing, mounted centrally upon a bogie fitted with castors, carries rods or brackets projecting on either side. Upon these brackets rest trays, open upon one of the longer sides only. The loaves are set upon these trays, which fit the width of the drawplate, and are slid off upon the latter, as shown in the illustration. Fig. 73. Fig. 73. Loading Drawplate from Setter. Fig. 74. Improved Setter. U F 658 THE TECHNOLOGY OF BREAD-MAKING. Cloths, fixed to the central upright of the setter rack, are spread over the loaves while proving. On another plan, the setter boards come close together, and with closed sides to the rack, are kept protected from draughts ; the trays are then placed upon the rack with their open side inwards (see Fig. 74). 748. Final Prover. — Something more than the above is required, especi- ally for dealing quite satisfactorily with cottage or other loaves that are made from two pieces, which are “ topped,'" i.e., placed on top of one an- other. It is necessary, in order to get the best results, to give the two pieces w'hich are to form the loaf a further rest, after coming from the finishing moulder, and to meet this requirement a secondary or final prover is now being placed upon the market. Fig. 75 shows a longitudinal section of s -f s e y s reeT» Fig. 75 . Final Prover. this machine, from which it will be seen that the dough-pieces are placed upon trays similar to those used in the first automatic prover, and moving intermittently. The loaves are given a maximum proof of 10 minutes, while the capacity of the’machine is equal to the output of the full automatic plant. The loaves are removed from the prover by hand, ready to be placed 'on the setters. The Fully Automatic Bakery is not yet in operation in this country (if anywhere), but will before long in all probability become an accomplished fact ; the subject is dealt with in paragraph 762 because it is necessary to first^consider the question of ovens in all its bearings. 749. Ovens. — This subject is still one of the most vital importance to the baker, and although the oven is obviously the oldest item in the equip- ment of his business, yet it has undergone greater developments during the present generation than in all the previous history of the baking trade. Rif dealt with exhaustively, the subject of ovens would occupy a large volume by itself, and therefore only so much of it can be freated here, as applies to the average modern requirements and as specially affects large separate interests in this country. Among general types it is necessary to discriminate between ovens heated (1st.) internally, (2nd.) in part in- directly, and (3rd.) by purely mechanical means, Le., quite externally. 750. Internally Heated Ovens. — These may be dismissed very shortly. THE MACHINE BAKERY AND ITS MANAGEMENT. 659 They consist merely of a masonry or brickwork chamber, communicating with a chimney and heated by fire direct, applied in various ways. The heat thus stored is utilised, after the oven has been swept out, for baking the bread. During all known history until modern times this was practi- cally the only principle applied to ovens for bread-baking purposes, and it is undeniable that if the manipulation of such an oven is properly under- stood and attended to, perfect results as regards baking can be obtained. The principal objections are want of fuel economy, loss of time in re-heating, utter dependence upon skill, and absence of hygiene. 751. Hot Air Ovens. — These are subject, more or Jess, to the same objec- tions. Their construction differs from that of internally heated ovens by the furnace or fireplace being independent of the baking chamber. The heated gases from the fire are conducted through flues placed, as far as possible, in such a manner as to enable the baking chamber to be heated by the tiles, which form the covering or walls of these flues. The waste gases are, or may be, also admitted eventually to the baking chamber itself. Dampers are introduced with the object of regulating the heat, but are not invariably successful. Provided that such ovens are well designed, they bake well, and are more nearly continuous than internally fired ovens. Against this must be set the drawback that most ovens of this kind consume considerable amounts of fuel. Unless exceedingly well built, the obviously numerous flues render frequent repairs of this type of oven necessary. 752. Mechanically Heated and Electric Ovens. — ^These represent the modern development, and lend themselves to specialisation in astonishing variety, of which the leading examples will be reviewed after a short general survey of the “ mechanical means available for heating the ovens. This class of oven may be fairly described as externally fired, but internally heated, the significance of which charactisation will in due course become clear. Ovens heated electrically would certainly fulfil the most exacting require- ments in every respect, were it not for the fact that the electrical generation of heat absorbs far too much energy to allow of working costs which are commercially practicable. Apart from miniature ovens, for laboratory work, a few electrically heated ovens have been built, but the amount of current consumed, about 80 kilowatts per one sack batch, is so enormous that, however low a price per B.T. unit be assumed, the cost will be seen to be quite prohibitive. Some startling revolution of the means for producing electrical current, or some equally wonderful invention for the conversion of electrical energy into heat, must therefore be awaited, before electrical heating of ovens can become a question of practical politics. 753. Perkins’ Tube or Steam Pipe Ovens. — As a matter of fact, Perkins’ invention of the closed circuit system, and the subsequent improvement thereon embodied in the “ Perkins ” sealed-end tube, was the epoch-making departure from the accepted notions of his day, which has brought about the revolution in ovens effected in recent years. It is an interesting testi- mony of the value of Perkins’ invention that the first man to employ ovens of his make, Mr. H. W. Nevill, built up in comparatively few years an enor- mous business. The Perkins’ invention is based upon scientifically correct principles. The boiling point of all liquids bears a definite relationship to the pressure to which the liquid is at the time subjected. The higher the pressure the higher is the temperature. The following is the principle of Perkins’ apparatus : — A system of hermetically sealed pipes, completely filled with water, is provided, and at its highest point an expansion vessel r 660 THE TECHNOLOGY OF BREAD-MAKING. is attached in order to accommodate the extra volume of the water when heated. By exposing a suitable proportion of this system of piping to the action of a fire the pressure in the apparatus was enabled to rise to the point corresponding to a temperature adequate for the baking of bread. Obviously the greater portion of this apparatus was arranged to be within the oven chamber, while the portion exposed to the fire, arranged as a coil in a brick-lined iron furnace, was placed at any convenient point, as in a stokehole or room adjoining the bakehouse. Many ovens were constructed in this manner, and remained successfully at work for many years. Perkins, however, soon concluded that it would be better to dispense with any form of joints for connecting up the various lengths of pipe, from which his apparatus was constructed. (The joint which he invented was neverthe- less remarkably efficient, and is the only one used to this day for this class of work, including the “ loop-tube "" ovens referred to later on.) He therefore adopted the plan of using a large number of single straight tubes, welded at each end, and with a portion of each tube projecting into a furnace constructed at the back of the oven and fired from a stokehole separate from the bakehouse. These tubes were set in two rows, the lowest of which acted as firebars, and upon them the fire rested. To this day this oven is the prototype, and apart from improvements in details and adaptations to particular require- ments remains unaltered. These single sealed tubes possess a practically unlimited life — they have been tested carefully after forty years of hard continuous service, and have been found absolutely intact and fit to con- tinue their work indefinitely. They obviously avoid the risk inseparable from joints, and, unlike tubes arranged in complicated coils and intricate loopings, are readily and inexpensively replaced, should occasion arise, without interruption or disturbance of working. The so-called loop-tube ovens are a half-way stage between Perkins’ earlier and later systems. The tubes, instead of being sealed at either end, are endless ; that is to say, have their ends jointed up to form a continuous tube, just as is the case in Perkins’ first construction. Wliile each loop-tube is therefore much longer and more complicated in shape than Perkins’ later straight tube, it is shorter than the circuit employed in Perkins’ first oven. The loop-tube has nearly all the faults of the first Perkins’ oven, but lacks the best points in the straight tube ; yet experience proves that the Perkins’ sealed-end tube accomplishes everything required of it by the baker, and is not excelled by the loop-tube in any single direction. Claims have been made on behalf of the loop-tube, in that ovens employing it are more economical in fuel than are ovens fitted with sealed-end pipes. This is not borne out by facts, if ovens of modern construction are compared under equal conditions ; what gave a certain amount of colour to these statements is that the long narrow' furnaces peculiar to earlier Perkins’ construction need considerable care to ensure that the consumption of fuel be kept to a minimum. As w'orkmen are careless, and mostly fire in the manner involving least trouble to them- selves, the fuel consumed in ovens with these long narrow furnaces usually exceeded considerably the amount actually required. The “ Perkins ” ovens have, how'ever, for some years been equipped wffih furnaces which make this impossible, and practically restrict the consumption of fuel to the amount actually required. It follow'S that the sealed-end tube is considered preferable, and the reasons, in so far as they affect the baker, may be shortly stated thus : it lends itself to constructions which are as economical, as uniform in baking,^and as continuous as any that are possible with any other system. In addition, it is more durable, involves less risk, avoids all possibility of an oven being put temporarily out of use, and if replacements are required, enables these to be carried out at a nominal expense. As the original patents for these THE MACHINE BAKERY AND ITS MANAGEMENT. 661 various systems referred to have now expired, they are all equally avail- able for oven manufacture. 754. Producer Gas Firing. — This has proved the subject of an interesting development during the last ten years. The firing of individual furnaces to each oven naturally calls for considerable labour in a bakery with a number of ovens, and to a certain extent makes the maintenance of suitable tempera- tures dependent upon the care of the stoker. With gas firing these draw- backs are dispensed with and the oven temperatures are controlled from the front of the oven and can be readily supervised by the foreman. A gas producer similar to that described in paragraph 706, but without arrange- ments for cooling, scrubbing and “ purifying ” the gas, is employed, and the hot gas is conveyed to the oven furnaces, there to be burned, by the aid of a secondary air supply, in such a manner that the flames play upon the ends of the steam tubes. This air supply is pre-heated by the waste Fig. 77 . Stokehole of Producer Gas-Fired Ovens. gases from the furnaces. This system has been applied to a large number of ovens in this country, is quite successful, and is certainly most cleanly and convenient in working. There is no fear of danger from any source or of breakdown, and the only point needing to be carefully watched is that the periodical cleaning of the gas mains, valves, and burners, from which the dust that gradually accumulates has to be removed, is done conscientiously. It is obvious that although 99 per cent, of the gas and air passages may be perfectly clear, if only at one point an accumulation is left, the whole of, or such part of the ovens as happen to be on the chimney side of the obstruc- tion, may work sluggishly. This cannot be considered a fault in the system, it is only mentioned as a point that calls for attention, and is similar to the dependence upon proper lubrication of the best running bearing ever made. From these remarks it will be seen that easy access to all gas and air mains, valves, and passages, is a matter calling for the engineer’s careful attention. Any one intending the erection of a new bakery, with not less than six 662 THE TECHNOLOGY OF BREAD-MAKING. ovens, should certainly give the question of gas firing his careful consider- ation. Fig. 77 shows a view in the stokehole of a large bakery, with rows of ovens, each fired from a separate producer ; the absence of fire-doors and the generally “ clean "" appearance of the oven-backs, is very striking. The small circular manholes are the sighting doors, through which the flames can be seen playing upon the pipes ; the square patches close to are open- ings giving access to gas mains, burners, etc., for cleaning purposes. The coke is kept on the top of the ovens and is trolleyed to the producers as convenient ; the producers are large enough to require filling up only once in 12 hours. 755. Setting Bread, — The system of setting bread in a peel oven, by means of the ordinary peel, is too well kno™ to need description. An attempt has been made to provide mechanical means of performing this operation (Dempsey’s patent), and so far as the working of this ingenious apparatus is concerned it performs the task well. Nevertheless the idea is not likely to meet with general adoption, because it fails to meet the con- ditions, which are necessary to-day, for producing a generally saleable loaf. As regards drawplate ovens the question of setting has been dealt with under paragraph 747 (see Fig. 73). 756. Oven Types. — The withdrawable baking plate was the subject of practicable proposals by Perkins. At a later period “ Wieghorst’s ” early productions made their appearance ; following upon these the dravq)late proper (Pfleiderer’s patent) was introduced largely into this country towards the end of the last century, and has since spread all over the civilised world. The dra'wq)late proper, with plate travelling independently upon the draw- plate carriage, employing only rolling bearings inside the oven, and leaving the bakehouse floor entirely unobstructed when not drawn out, has since the beginning of this century certainly become the standard bread oven. Fig. 78. One-Deck Drawplate Ovens. THE MACHINE BAKERY AND ITS MANAGEMENT. 663 Fig. 79. Two-Deck Drawplate Ovens. Fig. 80. Stokehole of Coke-Fired Ovens. 664 THE TECHNOLOGY OF BREAD-MAKING. Replacing old ovens in existing bakeries, and nearly always being installed in aU new bakeries with any pretence to being abreast of modern ideas the drawplate has long ago demonstrated the fact of its entire suitabihty for all baking requirements. Fig. 78 shows a battery of one-deck drawplate ovens, which it may be remarked incidentally are producer gas -fired, although the only distmguishing feature as regards this will be noticed in the small valves fitted above each oven close to the “ dummy '' clock. Fig. 79 shows a battery of two-deck ovens, coke fired. Fig. 80 gives a view in the stoke- hole of a coke-fired battery, from which the smallness of the modern furnace will be noticeable. Drawplates are made in many different sizes, to suit requirements of trade as well as to conform to restrictions in regard to space. It may be taken that the plate should not exceed 6 ft. in width in all cases where setting has to be done by hand (conf. paragraph 699), but when only bread is baked which may be handled with setters, the width may be as much as 8 ft. 4 in. Greater widths should be avoided, as leading to difficulties in setting, on account of the heavy weights to be handled. S^lit Drawplates. — Fig. 81 shows a very useful modification (Pointon’s Tig. 81. Oven with Split Drawplate. patent) of the standard arrangement, enabling a drawplate oven to be adopted in bakeries possessing only a very limited floor space. The plate is cut transversely into two equal halves, and when drawn out, the special gearing shown enables the first half to be lowered, so that the back half can be drawn forward over it. After setting the batch on the back half the process is reversed. These ovens are in actual use and answer admirably ; it will be seen that they not only enable a drawplate to be used where it would be otherwise impossible to do so, but that a plate, about 11 ft. long, can be used in a 6 ft. space : in less space therefore than a similar size peel oven could be worked in. Combined Drawplate Peel Oven. — Fig. 82 shows this very useful combina- tion. The carriage of the drawplate carries a chequered iron plate platform (barely visible in the illustration because almost entirely hidden by the drawplate itself) from which the peel oven is conveniently worked. The step just above the car wheel gives easy access to this platform. With regard to the firing of this oven refer to “ furnace arrangements "" further on. Portable Drawplate Ovens . — A useful small oven, very suitable for caterers, is shown in Fig. 83 (Ihlee's patent). The fact that the special design of THE MACHINE BAKERY AND ITS MANAGEMENT. 665 Fig. 82. Combined Drawplate and Peel Oven. Fig. 83. Portable Drawplate Oven. running gear employed dispenses with all outer supports, makes this oven quite self-contained and truly transportable. Oven Types : Peel Oven . — The standard peel oven, although made in any size to suit requirements, does not call for lengthy description. Figs. 666 THE TECHNOLOGY OF BREAD-MAKING Fig. 84. Single-Deck Peel Oven. Fig. 85. Double-Deck Peel Ovens. 84 and 85 show typical arrangements of one- and two-deck varieties, the former fitted with pro vers under, the latter with pits for working the bottom ovens. THE MACHINE BAKERY AND ITS MANAGEMENT. 667 Portable Ovens. — Fig. 86 shows a very excellent two- deck specimen, with prover and hot-water tank. p- | Field Ovens, as shown in Fig. 87, are mounted on platform waggons and en- able baking of the very best type to be carried on for troops in camp or on the march. This two-deck oven, although only weighing 22 cwt., bakes rations for over 2,000 men per day : a very good indication of the effi- ciency of the steam-pipe principle. It may be fired with coke or can be heated with wood : even green wood cut on the march answers the purpose. The insulation on these ovens, despite their elegance and lightness, is so excellent Fig. 86. Portable Oven. Fig. 87. Field Oven. 668 THE TECHNOLOGY OF BREAD-MAKING. that baking has been carried on with 3 in. of unmelted snow lying on the top of the oven. Shi'p Ovens . — War ships and merchantmen are now as well equipped as any establishment ashore, and carry fully equipped bakeries with knead ing machines, mostly driven by electric motor direct, and steam-pipe ovens. Fig. 88 shows one of the large size and substantial two-deck ovens carried by our large liners. & 'Jerkins yfTffiSOMUSS Fig. 88. Ship Oven. Hotel Ovens . — Large hotels and businesses with dining accommodation for large staffs frequently provide themselves with modern equipment, and Fig. 89 shows a typical case of this kind. In this the oven seen on the left-hand side is a “ Vienna oven with sloping sole, powerful steam generat- ing apparatus, steam valve for drawing ofi vapour, and patent oven-light to protect the gas jet from the effects of steam. This type of oven is fitted with the Monier sole, referred to in a subsequent paragraph, and admirably bakes rolls of the true Vienna style — that is to say, rolls with a thin “ egg- shell crust and perfect bloom and gloss for consumption within a few hours of baking. Vienna rolls, as more often required in this country, require an oven somewhat differently arranged, and are better produced by the aid of steam from a boiler as they must be soaked more thoroughly and require a heavier crust so as to keep brittle for a longer period. THE MACHINE BAKERY AND ITS MANAGEMENT. 669 Fig. 89. Hotel Oven. Fig. 90. Coverplate Oven. 670 THE TECHNOLOGY OF BREAD-MAKING. Coverplate Oven . — A very special type of oven has been quite lately pro- duced, which cannot be classified either as a peel or drawplate, and to which the name of “ Coverplate ’’ oven (Ihlee’s patent) has been given. It is essentially a hot plate, fitted with a removable lid or cover, in which is arranged a system of pipes to give top heat. The idea is to give a large batch capacity (40 dozen 2 1b. loaves) in a minimum of working space, with the least possible weight and expense. The oven is designed to deal with Scotch batch bread, but might also suit similar classes of goods much made in Ireland. The furnace gases can be taken over the tops of the loaves to give the “ flashing '' effect required in Scotland. Figs. 90 and 91 show tlie Fig. 91. Coverplate Oven with Cover Lifted. oven as fitted in a Glasgow bakery, where the work done appears to be excellent and to meet the high standard demanded there. It remains to be seen if the oven will find anything like general favour ; but it has done so well hitherto, that any one contemplating ovens for work of this class should certainly make every inquiry into its capabilities. When the cover is lifted, as shown in Fig. 91, the method of procedure is of course exactly the same for setting and drawing a batch as would be the case with a drawplate. For the many existing bakeries in Scotland, with flats on upper floors, the scheme, if practicable, would appear to possess marked advantages because of tlie great saving in weight, combined with economy in floor space. Arrangement of Furnaces . — All the ovens referred to can be built to be fired from the front, back, or at either side, but of course preference must be given to back firing in all cases where exigencies of space do not make this THE MACHINE BAKERY AND ITS MANAGEMENT. 671 impossible. One furnace to two baking chambers, as in two-deck ovens, should be avoided because, notwithstanding any claims to the contrary, effective control of each chamber is only possible when each chamber has its own furnace. The drawback to having a furnace to each, in two-deck ovens, has hitherto been that this construction entailed having the sole of the Fig 92 . Beanes’ Furnace Construction. upper oven at an inconveniently great distance from that of the lower one. Beanes’ patent construction. Fig. 92, avoids this difficulty, and enables the soles to be kept at the same minimum distance apart as in the two -deck oven with one furnace. For the purpose of these observations 672 THE TECHNOLOGY OF BREAD-MAKING. it is assumed that each chamber has at least two rows of tubes, as in some* cases ovens are built with two decks and only three rows altogether. This is bad practice, and does not lead to a saving at all commensurate with the loss in efficiency, durability, and continuity of the oven. 757. Oven Fittings. — Drawplate ovens are commonly equipped with a “ dummy clock to each chamber for marking up the time at which the batch should be drawn. There is also a mercurial thermometer and means for injecting steam, while efficient steam generators may be arranged for if required. Peel ovens are fitted with a thermometer, and either a gas bracket or patent oven-light as may be desired. The latter has the advan- tage of fighting up the oven without being effected by the steam, and is certainly to be strongly recommended on that account ; oil lamps are sup- plied where gas is not available. Doors, arranged to slide vertically, should be fitted for Vienna ovens, or where small goods require setting in a bath of steam, as the doors may then be readily adjusted to a convenient height,, while retaining the steam at a lower level than would otherwise be the case. Pyrometers are quite out of date in steam-pipe ovens, as the temperature can never rise to a point wffiich would endanger a thermometer, which is,, if of good make, absolutely reliable and will always read accurately. Good working instructions should be insisted upon with new ovens, and kept in a conspicuous place in the stokehole. Their observance should be rigidly insisted upon by the proprietor or manager. i As regards oven soles, all ordinary styles of bread current in this country will be baked satisfactorily on iron soles. A very useful method of indelibly marking each loaf with the name or trademark of its maker is possible with drawplates, by having the plate divided into suitable squares, in each of which the desired mark is cast, so that it is positively baked into the loaf. The plan is in use in many places and answers admirably. For slab cakes, sponge cakes, fingers, and similar goods, as well as for Vienna rolls, etc., a sole of earthenware material is often preferred. “ Monier "" soles, as manufactured by Werners, have proved entirely satis- factory in these cases, and can be strongly recommended as having now stood the test of over ten years’ continuous working. Tiles, unless sufficiently tliin, must be condemned, as otherwise they interpose too great a resistance to the transmission of heat from the tubes, the safety of which is thereby endangered. The cases where iron soles do not fully cover all requirements are, how- ever, comparatively few and far between. 758. Automatic Ovens. — Travelling ovens of the type used in biscuit manufacture are not suitable for bread-making ; at least they do not lend themselves to the production of modern thin-crusted loaves with a rich bloom, adequate bulk, and baking with a minimum loss of weight in the loaf. As no bakery exists in this country as yet employing an automatic bread oven, no detailed reference can be made to it here, as the authors have throughout confined themselves to dealing with constructions, the practical working of which has come within their personal experience. The subject is, however, of sufficient interest to warrant the announcement that a fully detailed scheme has been patented. This has been carefully examined and appears to be perfectly practicable, so far as such a conclusion can be arrived at without the experience of actual practice to confirm its value. It will be interesting to see what the next few years will bring forth in this direction. The chief barrier to progress in this matter is the diversity of styles in loaves produced in the average bakery in this country, and probably if an oven of the auto type could be tried upon an absolutely uniform trade THE MACHINE BAKERY AND ITS MANAGEMENT. 673 of sufficient dimensions, such technical points as still require to be proved practicable would soon be established beyond doubt. 759. Oven Firing. — It is not possible to give any detailed instructions on this subject, as the treatment must necessarily vary considerably for different makes of ovens. It may, however, be said that where possible in regard to cost, coke is much the cleanest and most satisfactory fuel to use. It saves much trouble and dirt and avoids all risk of creating a nuisance by the emission of smoke. With every kind of fire, and especially with ovens, “ little and often should be the golden rule in adding fuel. The saving of trouble by filling furnaces to their fullest capacity, and often beyond that, is pernicious : it literally wastes an enormous percentage of the fuel and leads to exceedingly bad results in the bargain. Avoid burning rubbish, an oven furnace is not a destructor, and avoid offal — egg shells, remains of meat, etc., especially if an oven be fitted with a copper boiler, as gases are formed which are detrimental to the copper. Do not use coke in large unbroken lumps — ^pieces about the size of a duck^s egg are quite the maximum that should be allowed. Keep the flues clean by regular periodical sweeping, and remember that the tube ends should also be kept clear of dust. For the rest it is necessary to follow the directions supplied by the oven builders. 760. Nature of Coke Combustion. — This subject is of great practical importance in connection with the whole question of the firing of oven fur- naces, and so merits a somewhat careful examination. First of all, coke has the advantage of producing an absolutely smokeless fire, and so soot deposits and their inconveniences are practically obviated. On the other hand, the flameless combustion of carbon produces heat which is not only intense but also very local, so that the furnace itself is very hot, in comparison with flues at some little distance. This necessitates careful designing, so that due provision shall be made for the ready transmission of this local heat ; granted proper arrangements, however, this localisation of heat in no way interferes with the perfectly efficient working of coke- fired ovens, it in fact constitutes an advantage. Although coke itself burns flamelessly, yet one usually sees more or less pale blue flame over the surface of a coke fire. This is due to a process similar to that which is utilised in a producer (see paragraph 706) and arises from the formation and subsequent combustion of carbon monoxide, accord- ing to the following equations. The air, in passing up through the red-hot coke of the fire, forms carbon monoxide thus : — 2C -f O 2 = 2CO. Carbon. Oxygen. Carbon Monoxide. The gas rises to the surface, and there, on meeting with excess of air, undergoes combustion, thus : — 2CO +02 = 2 CO 2 . Carbon Monoxide. Oxygen. Carbon Dioxide. In this way the production of carbon monoxide indirectly causes a flame combustion from coke, and thus produces heat in such a form as to be more readily conveyed away, so far as the flames will reach, from the furnace into the flues. But unless complete combustion of the carbon monoxide occurs, there is a very serious loss of heat. This is readily seen by studying the thermal effect of the burning of carbon and carbon monoxide respectively. One gram of the former evolves during combustion 8,080 heat units, while the same quantity of the latter produces 2,634 heat units. From the equations above given it is readily calculated that I gram of carbon produces 2-33 XX 674 THE TECHNOLOGY OF BREAD-MAKING. grams of carbon monoxide. And further, this quantity of carbon monoxide must produce in burning 2*33 X 2,634 = 6,146 heat units. But as the gram of carbon only evolves 8,080 heat units, we have 8,080 — 6,146 = 1,934 heat units produced in the burning of 1 gram of carbon to monoxide. Heat Units. Summing up : — Heat produced by 1 gram of carbon burning to monoxide . . 1,934 Heat produced by the combustion of the carbon monoxide yielded by 1 gram of carbon . . . . . . .. 6,146 Total 8,080 Wliatever quantity of carbon monoxide, therefore, that escapes combustion, means a loss of over three-quarters of the heat -producing power of the carbon it contains. To prevent this loss, air should gain access to the coke gases after they leave the coke. In practice this end is sometimes attained by letting the furnace doors be slightly open — it is possible, however, by having the opening too large, not only to cut oh the draught from the fire, but also to absolutely cool the oven by the admission of excess of cold air into the fiues. Theoretically, the right thing might appear to be to keep the furnace closely shut, and thus favour the production of carbon monoxide, providing for its combustion, beyond the fire, by admitting air on the flue side of the “ bridge ” or back wall of the furnace. Such an opening would need to be regulated so as to admit the exact quantity of air with the utmost nicety, as too little would mean imperfect combustion, and too much a direct cooling of the oven. In practice there would be considerable difficulty in carrying out this idea. Not only among those in charge of ovens, but also furnace men generally, there is a widely-spread opinion that the admission of steam between the firebars into the fire is greatly advantageous. To such an extent is this view held, that firebars have been patented and used in boilers, which are made hollow and perforated for the admission of steam upwards into the furnace. From extensive experiments that have been made by large steam users, and which have come under the authors’ notice, they are assured that a distinct saving of fuel is gained when measured by that most crucial of all tests, a three months’ fuel bill. In these tests the only difference made was that steam-admitting bars were substituted for the ordinary solid fire- bars. Furnace men obtain, roughly, the same effect by placing vessels of water in the ashpit, by the evaporation of which a supply of steam is produced. The advantages claimed are (1) comparative absence of clinker forma- tion, (2) longer life of firebars, (3) saving in fuel. Undoubtedly claims 1 and 2 are correct, especially in cases where the fire is required to be maintained at very bright or white heat. Clinkers are due to oxidation of the iron of the bars, and subsequent fusion of such oxide into a slag, by combination with siliceous matter from the coke. So far as steam helps to avoid clinkering, it is probably due to its exercising a local cooling effect on the bars. If clinkers are avoided, there is necessarily a clearer fire, and as a necessary consequence a better draught, as the air finds its way through more readily. Evenly distributed draught tends to prevent the formation of clinkers, and the absence of clinkers helps the draught, so that each of these reacts favourably on the other. The third claim of saving of fuel requires careful examination. It will be best first to deal with the chemical changes produced by the passage of THE MACHINE BAKERY AND ITS MANAGEMENT. 675 steam over red-hot coke : carbon monoxide and liydrogen are evolved in abundance according to the following equation : — C + H2O = CO + H2. Carbon. Water. Carbon Monoxide. Hydrogen. Subsequently, with excess of air we have : — CO -f- H2 -[- O2 — CO2 H2O. Carbon Monoxide. Hydrogen. Oxygen. Carbon Dioxide. Water. It will be noticed that the same quantity of steam which passes into the fire escapes as such at the close of the combustion processes ; therefore the steam neither increases nor diminishes the number of units of heat produced by the ultimate combustion of carbon to its dioxide. Any saving can only be due to the combustion being to a much greater extent a gaseous one ; and, as has been before explained, gaseous combustion means more ready and even heat transmission, and therefore economy. Absence of clinker and evenly distributed draught are in themselves of course indirect sources of economy of fuel. It is a somewhat popular error that a gain due to an absolutely increased amount of heat is effected in this case by the combustion of the hydrogen produced : it must be remembered, however, that precisely the same quantity of heat is required for the dissociation of water into its component gases as is set free by their subsequent combina- tion. Consequently, no outside heat is liberated by this decomposition and recombination of the constituents of water. 761. Water Heating. — The problem of heating water for a bakery requires more careful consideration than it usually receives. The widely current notion that nothing could be simpler or better than a boiler over the oven furnace is perhaps not unnatural ; especially bearing in mind that such an arrangement ensures a good supply of warm water directly on commencing work after a period of rest. As a matter of fact, however, there are serious objections to this plan, and an independent apparatus must be recommended as preferable. In the first place, it is vTong to sup- pose that there is any saving in fuel by having a boiler over the furnace ; assuming of course that in comparing such an arrangement with an inde- pendent heater both are properly constructed. Nature never gives anything for nothing, and water cannot be heated in an oven boiler without a corre- sponding amount of fuel. There are of course ovens which part with their waste products of combustion at so high a temperature that they can be utilised for heating water in adequate quantities ; but these cannot be here considered as we are dealing with modern ovens, which, if properly con- structed, do not waste heat to this extent. In the second place, it must always be remembered that a boiler constitutes a local demand for heat, at such times especially when much hot water is drawn ofi, and this necessarily tends to rob the oven of heat in an uneven manner, besides checking the temperature generally at times which bear no relation whatever to the legitimate functions of an oven. Further, a boiler buried in brickwork is much subject to deterioration, while being at the game time inaccessible to inspection ; the result is therefore usually that the time comes when it gives out without warning, drowns the fire and spoils the bread by interfer- ing with the baking, to say nothing of the inconvenience caused and the probable disturbance of work while repairs and renewals are effected. Excellent independent heaters are now available, and a very good type is illustrated in Fig. 93 (Perkins’ patent). The boiler proper, consisting of a cylindrical vessel, wuth a domed lid which is removable, will be seen to be mounted upon a cyhndrical furnace. Perkins’ tubes, arranged in a circle, pierce the bottom or tube plate of the boiler, and convey the heat from the 676 THE TECHNOLOGY OF BREAD-MAKING. fire, which lies within the basket of pipes formed by the tubes, to the water above. The fire therefore lies on a small circular fire-grate, and is walled in on all sides by the vertical tubes. Thus no fii^ebrick lining is necessary, and renewals are confined to the fire-grate, a very small affair ; whereas the boiler top can be readily lifted for the removal of scale. This scale can only form on the tubes as these constitute the only heating sur- face for the water, and owing to the fact that expansion and con- traction of the tubes takes place, the brittle scale automatically chips off as soon as it has accu- mulated to any appreciable thickness and collects at the bottom of the boiler ready for removal. The boiler must always be kept full of water, and this is readily assured by a supply being provided by means of a ball- cock supply tank (as shown in illustration) under a sufficient head to drive the water to the highest point at which it is de- sired to draw off. Before leaving this subject it is necessary to point out the importance of always selecting materials suitable to the nature of the local water supply. Hard waters are usually neutral to galvanised surfaces, and in all such cases therefore galvanised pipes and boilers meet all prac- tical requirements. Naturally, Fig. 93 . Water Heater. hard waters deposit the greatest amount of scale, and the appara- tus described above is then the best, as no trouble will ensue so long as the scale deposited at the bottom of the boiler is periodically cleaned out. Soft waters, especially moor waters derived from areas with large deposits of peat, corrode iron and steel very rapidly, especially when hot ; and gal- vanising also proves no protection in such cases. To meet these conditions, the independent heaters are supplied in copper, as regards all surfaces which come in contact with the water, or to avoid undue expense, with copper- coated surfaces. As entire destruction through pitting and corrosion may take place in so short a time as 12 or 15 months where galvanised iron or steel are used, the importance of this point will be appreciated. 762. Complete Automatic Bread Bakeries. — Before leaving the subject of bakery equipment it may be of interest shortly to refer to bakeries which dispense entirely with skilled labour ; excepting always, of course, the need for good judgment and expert knowledge required in making doughs THE MACHINE BAKERY AND ITS MANAGEMENT. 677 by the aid of the machines and regulating properly its subsequent growth and development. Such bakeries are by no means beyond the range of practical politics ; there is, in fact, no reason why they should not at once come into everyday use, provided that the output required is sufficiently large (say 500 sacks per week and upwards), and above all of a uniform kind. Assuming a trade of 500 sacks per week consisting of nothing but 2 lb. tin bread (or of the cottage or coburg varieties), eight men would be sufficient to take the flour from the flour store and deliver the finished bread on to trucks in the bread-room, and of these only three men would need to be bakers. It will be clear that the cost of production would thus be brought down to a minimum, and as the baked bread is discharged into the bread- room by the automatic oven, transportation throughout the whole process is carried out by mechanical means. The authors have studied this scheme carefully and believe in its entire practicability. 763. Bashing Machine for Irish Loaves. — This appliance is employed for automatically dealing with the loaves as they come from the finishing moulder (paragraph 741) in the case of Irish batch bread. As a useful appliance suitable for the considerable portion of Ireland, in which the local loaf is of the type known as “ close set or “ batch bread, a description of this machine (Parkinson’s patent, Messrs. Joseph Baker & Sons, Ltd.) follows. Although not applicable to bakeries in general, the machine is typical of the modern development in the direction of j replacing manual labour involving personal contact with the bread as far as at all possible. The illustration. Fig. 94, shows the feeding end Fig. 94. Bashing Machine for Irish Loaves. 'of the machine to the left. A conveyor from the finishing moulder is arranged to run across the feeding end of the basher, parallel to the axis of the roller supporting the travelling band A. The attendant takes the loaves from the conveyor and places them against the spacer B, which is timed to operate intermittently at a speed corresponding to that of the moulder. After the row of loaves has been deposited against the ■spacer, this latter rises vertically to clear the loaves and permit them to be carried along by the travelling band A, which also moves intermit- tently. The loaves travel through the enclosed space or tunnel C, thus being allowed time to “ recover,” and on emerging from the tunnel are sub- 678 THE TECHNOLOGY OF BREAD-MAKING. jected to a slight bashing and centring operation under the preliminary basher D. On reaching the final basher E the loaves undergo the final bashing process, and are simultaneously stamped with the name of the maker or his trade-mark. On reaching the end of the travelling band at F, they are removed and set on the setter boards ready for the ovens. 764. Scotch “ Chaffing ” or Moulding Machine. — Another special adapta- tion to local requirements is represented by a machine for performing the final operations required in “Scotch'' batch bread (Pointon's patent). In the manufacture of Scotch bread, although the dough-making process foUows entirely different lines to those generally adopted in England, the machines used, as far as dividing, handing-up, and proving are concerned, are exactly similar to those described in paragraph 740 et seq. But the final operation of moulding the loaf is on an entirely different principle to that of the balling-up type so far referred to. Instead of working the dough- piece up into a ball shape as described in paragraph 740, the Scotch practice demands that the piece be pressed out into a fiat sheet, stretched, folded Fig. 95. Scotch Chaffing Machine. over, pressed again, and finally folded into an oblong packet ready to be placed on the setter. These operations are very difficult to accomplish mechanically, especially as they are of a non-consecutive nature, but would appear to be perfectly accomplished by the machine illustrated in Fig. 95. The dough-pieces upon emerging from the prover are fed automatically into rolls, from which they emerge as flat sheets. These sheets of dough are picked up by the operative and placed upon one of the pallets (A) of the “ chaf- fer," and carried by intermittently moving chains over the “ flappers," shown at (B). Here the two ends of the dough sheet are turned over upon themselves, and upon reaching the next stage are pressed and flattened down firmly. The next movement causes the sides of the fiexible pallet to be gradually brought up and towards each other, causing a fold in the dough- piece at right angles to the last folds made. Finally the pallet is drawn THE MACHINE BAKERY AND ITS MANAGEMENT. 679 through between two closely spaced walls, causing the now uppermost edges of the dough-piece to be firmly joined and pressed together, giving just the square-ended oblong packet desired. It will be seen that the working of the machine is ingenious, and although it has only been just put upon the market in time to be referred to here, the authors believe that it will be found to answer the requirements which it was designed to meet. 765. Bakery Registers. — An almost integral part of the economy of a machine bakery, and in fact any bakery of modern pretensions, is a register of particulars of the making of each batch of the day's work. This should be in book form, and affords, when properly kept, a most valuable record of work done, and also gives the means of checking same from day to day. The authors have had printed a register in which the following is the heading of the day’s work : — BAKEHOUSE REGISTER. Temperatuee. Day. Night. 19. . . . Highest .... .... . . , . Lowest .... .... .... Temperature of bakehouse at time of setting 1st sponge or dough There then follow the various column headings, arranged right across two pages of the book, in the following order : — Number and kind. Water (quantity). Temperature. Yeast, kind and quantity. Salt. Flour. Flour temperature. Sponge when set. Temperature when set. When taken. Remarks. Time when taken. Water. Temperature. Salt. Flour. Dough temperature. Oventime. No. of Loaves. Remarks. Such a register may be amplified, simplified, or modified, according to the requirements of any particular mode of working. The system of testing the temperature of a sponge when set, and when taken, often gives useful information as to its condition. With any uniform method of working, the amount of rise in temperature is very nearly a constant quantity. When the rise is excessively low, the sponge is likely to have been starved or the yeast to have been weak. If, on the other hand, there is an abnormally high rise, the fermentation will have been too vigorous, and have proceeded beyond its proper limit. In either case a useful diagnosis of the condition of the sponge is afforded at a time when it is possible to take steps toward remedying either evil. Subject to certain limitations, the same remarks apply to straight doughs. CHAPTER XXV. ANALYTIC APPARATUS. 766. Commercial Testing and Chemical Analysis of Wheats and Flours. — As a matter of convenience, the various analytic operations involved in the testing and examination of wheats and flours are divided into two classes : first, those which are more readily performed, and which afford information having the most immediate bearing on the actual value of these bodies ; and second, those determinations which are more purely chemical in their nature. The operations of the first class are comprised under the heading of “ Commercial Testing of Wlieats and Flours ” ; their nature is such that they may be performed personally either by the miller or baker. The second series of tests requires rather more chemical know- ledge and experience : they consequently appeal more particularly to the students of milling and balong who have had the advantage of a course of chemical training in a properly appointed laboratory. A description of the laboratory, and of the principal analytic apparatus used in weighing and measuring, will now be given as an introduction to analysis. 767. The Laboratory. — ^For the benefit of any millers and bakers who may wish to fit up a laboratory for themselves, the following few hints as to utilising a room for the purpose are here inserted. If any work is to be done beyond the roughest experiments, a balance and microscope will be requisite ; these delicate instruments must be kept free from dust, and so cannot be exposed to the ordinary atmosphere of the mill ; they should therefore be placed in either a private office or study, and covered over when not in use. For the other purposes of a chemical laboratory, almost an}^ room, or part of a room, can be made to answer. A working bench or table should be fitted in as good a light as possible, at a convenient height. Gas, when obtainable, should be laid on to this bench by means of a pipe terminating in a nozzle, over which a piece of india-rubber tubing can be slipped. There should be near at hand a drain, over which is fixed a tap, with a good water supply. This tap should also have a small side tap, Avith nozzle for india-rubber tubing, in order to lead water into any apparatus in which it is required. These are almost the whole of the necessary fixings. There must of course be a few shelves on which bottles and the various apparatus may be kept. With time and money to spare, many additional fittings might be suggested. These can, if wished, be added afterward. 768. The Analytical Balance. — It is presumed that the student before attempting the following work, will have made himself famihar with the simpler chemical apparatus by their actual use in the laboratory. Quanti- tative analysis, as its name implies, is that species of analysis by means of which the quantity or amount of each ingredient in any particular body is determined. For purposes of analysis, quantity is measured and expressed either by weight or by volume. Accordingly, the chemist first of all requires some accurate means of determining with exactness both weight and volume. For purposes of weighing, an^accurate balance and set of weights are 680 ANALYTIC APPARATUS 681 necessary. Of these there should be in a laboratory at least three of dif- ferent degrees of sensibility. Taking the most delicate first, let us describe what may be termed the “analytic balance proper.'' This instrument requires to be made with the utmost care and accuracy, and is illustrated in Fig. 96. The speciality of this particular variety is that the beam is very short ; it is claimed for it that, as a result, the delicacy of the balance is increased, while the time in which a weighing is performed is lessened. On referring to the figure it will be noticed that the balance is enclosed in a case ; the bottom of this consists of a stout slab of glass, fixed on levelling screws. The front, back, and sides of the case are glazed ; and all open, the front and back by shding up, the two sides on hinges, as doors. The beam is suspended on a pillar, which in turn is screwed down to the bottom of the case. The beam carries at its centre a knife-edge made of agate ; this rests on a plane of the same material ; on each end of the beam there are similar knife-edges, and from these depend the scale pans. Wlien the balance is not in use, the beam, instead of bearing its weight on the^knife- 682 THE TECHNOLOGY OF BREAD-MAKING. edge, rests on a sort of cradle ; so, too, the end hooks carrying the pans- are likewise supported by the cradle. Underneath each pan there is also a small support on which the pan rests until it is required to set the balance in action. In the centre of the front of the balance, and immediately under- neath the glass base, is fixed a large brass milled head ; this, on being slowly turned by the operator, first lowers the supports from beneath the pans, then drops one portion of the cradle, and so suspends each scale pan from the terminal knife-edges of the beam, and next lowers the central knife-edge on to its agate plane, and permits the balance to swing. On turning the milled head back again, the opposite of these movements takes place in reverse order, and each knife-edge is gently lifted from the agate plane. The object of this is to prevent wear of the edges by their being continually in contact, particularly as a balance would soon be seriously injured by the jarring caused to knife-edges and planes by putting on and removing weights while these were in contact. It must be borne in mind, as a golden rule of weighing, that nothing must be added to or removed from either pan of the balance when the instrument is in motion. In order to show the movement of the beam, there is a long index finger descending from its centre and moving in front of an ivory scale at the bottom of the pillar. A description of the mechan- ism employed to effect these various movements is unnecessary, as they can readily be understood by a few minutes’ careful inspection of the instrument itseK. Some other attachments of the balance will be better understood when we come to describe the operation of weighing. If a student is working in laboratory under the direction of a teacher, he will find balances there, and already properly adjusted ; in case that he happens to have purchased one for his private use, all the adjustments will have been made by the maker, and should not be interfered with by him unless he is thoroughly acquainted with the mechanism of a balance. It should always be borne in mind that a balance must on no account be altered or re-adjusted except by some responsible person ; there may be several persons working with the balance, and the one, by altering it, and possibly setting it wTong, may upset the work of all the others. Suppose a student has procured a balance for his o^vn private use, let him place it in its permanent position, which should be on a stout bench or table in a dry room, and at a height convenient for weighing when sitting down. The light should, if possible, be from a window behind the balance ; that is, the balance should be so placed that the opera- tor is facing the light, which should not be glaring, while it should be good. Occasionally, in a balance so placed, the ivory scale at the base of the pillar is in such deep shadow as to be scarcely readable. This may be remedied by folding a piece of white cardboard at right angles and placing it in front of the scale. It will be below the range of the eye, and acting as a reflector will sufficiently illuminate the scale. A light coming from a high window behind the operator also answers, but a strong light from either side is not suitable for weighing. The first thing to do is to get the pillar of the balance vertical. In the balance, a plummet hangs from the back of the pilUr, immediately over a corresponding index point on the base ; the two levelling screws in front of the balance must be turned in one direction or the other until the plummet is directly over the index point ; the base of the balance will then be horizontal. In the next place carefully dust the beam and the pans with a camel’s hair brush. Then turn the milled head which actuates the balance, and allow the beam to vibrate ; it will most likely swing one way or the other immediately the beam is liberated, but if not, open the right-hand side door and waft a very gentle current of air down on the one pan with the hand. Close the door again, and watch the vibrations of the index finger ; it should be explained that all the sides of the case must be kept closed as much as possible during the operation of weighing. ANALYTIC APPARATUS. 683 The little ivory scale has its zero in the centre, the divisions count each way from it, and are usually ten in number on each side. Should the balance be correctly adjusted, the index finger will swing the same number of degrees each side of the zero, and after a time, as each vibration becomes shorter, will come to rest over the middle of the scale. Strictly speaking, the dis- tance travelled on each side must be slightly less than that of the other ; thus, supposing the index travelled to 9 on the left hand, it would, when the balance is correct, swing slightly less than 9 to the right, say 8-9, and then back to 8-8 on the left. With a good balance this diminution is so little for one or two vibrations that practically we may say that it should swing equally on both sides. Such a balance as that described is capable of weighing to the tenth of a milligram, with a weight of two hundred grams in the pan. In addition to this instrument a coarser balance is also necessary ; this should be capable of carrying a kilogram, and weighing to the hundredth of a gram. Bal- ances of this latter kind cost from thirty shillings to two pounds, and are similar in principle to that already described. 769. Adjustment of Balance. — In case when testing the balance the index does not swing to the same distance on either side of the zero of the scale, first of all again dust the balance most carefully, and test once more. In the event of this not removing the error, the beam must be re-adjusted ; there will be seen two little balls, one on either side of the top of the beam, and running on two slender horizontal screws attached to the beam — on the side which is the lighter, screw the ball very slightly from the centre of the beam, and again test. Repeat this until the two sides of the beam exactly counterpoise each other. Wlien once adjusted, a balance, if kept clean, needs no alteration for a considerable time, providing always that it be carefully and delicately handled. In different makes of balance the modes of adjustment vary ; the maker will, however, in every case either give directions or see to the proper adjustment of the instrument before it leaves his hands in case of its being a new one. For a very clearly vTitten and most interesting chapter on the mechanical principles and management of the balance, the student is referred to Thorpe’s Quantitative Analysis, published by Longmans & Co. 770. Analytic Weights. — After the balance, the next thing required by the chemical student is an accurate set of weights. As a rule the chemist returns his results in pereentages ; it is not therefore of very great impor- tance to him, from that point of view, what unit of weight he adopts. In England, ehemists either use grain weights or else those of the French metric system. Wlien grain weights are employed, the set contains pieces varying from the hundredth of a grain to 1,000 grains. From its much greater simplicity, weights of the metric system are now used to a much greater extent than grain weights. Not only is there this advantage of greater simplicity, but, in addition, they have become the international system for scientific purposes ; for this reason, as well, it is highly advisable that all chemists and students of chemistry should learn to work with these weights. Whatever weights are employed a few very simple factors suffice to convert those of the one denomination into those of the other. In Chapter I. is given a table of the most important metric weights and measures, together with their English equivalents. The set of weights employed for analytical purposes must be of the greatest possible accuracy. They usually range from 50 grams to a milli- gram. The heavier weights are made of brass and then electro -gilded ; the fractions of a gram are made of stout platinum foil. In shape, the brass weights are made slightly conical, and are each fitted with a small handle 684 THE TECHNOLOGY OF BREAD-MAKING. at the top, by which they must be lifted ; for the same purpose each of the platinum weights has the top right-hand corner bent at right angles to the weight. These weights are arranged in a box, each being placed in a separate compartment, those for the gram weights being lined with velvet ; the smaller weights are further protected by an accurately fitting cover of glass. For the purpose of lifting the weights a pair of forceps is provided ; this has its place in the box. Analytic weights must on no account be touched with the fingers. Most sets of analytic weights contain the following pieces arranged in the box in the order shown below ; — 50 20 10 10 5 1 1 1 2 0-5 0 001) 0-2 0-1 0-1 005 Rider. 0-001 1 0-001 j 0-005 0-01 0-01 0-02 The student will require to learn, not only the denomination of each weight, but also its place in the box. He must be quite as well able to read the weights he has placed in the balance pan from the empty spaces as from the weights themselves. As soon as the weights are done with they should always be returned to the box ; this should be further protected by being kept in a case made for it of wash-leather. The accuracy of all analysis depends on that of the weights ; too great care cannot, therefore, be taken to preserve them from injury. In giving the denominations of the weights above there is a place marked “ Rider '' ; the nature and use of this particular w'eight remains to be explained. The arrangement of the weights, as shown in Fig. 97, corresponds with the table just given of their value. Special attention must be directed to the “ Rider,'' which is drawn to its full size at A. The student must now refer again for a moment to the figure of the balance previously given ; he wdll there notice, at the top right- hand corner, a milled head ; this actuates a rod, at the other end of which, from a little hook, depends the rider, as showTi just over the left-hand pan. From end to end of the beam itself there also runs a graduated scale ; this scale is divided into twenty equal parts, the centre is marked zero, and the other graduations numbered I— 10 from the centre towards each end. Each ok these units is still further subdivided into 5 or 10 equal parts. This scale is the exact length of the beam, measured from one to the other of the terminal knife-edges. An inspection of the balance itself shows immediately that by means of the milled head and rod attached thereto, the rider can be placed astride the scale at any part of its length. The weight of the rider is one centigram, consequently, if placed in the pan of the balance, or at 10, the extremity of the scale, the effective weight of the rider is the same as its absolute weight. But if it be placed somewhere intermediate between the centre and end of the beam, its effective weight is between 0 and 1 centi- gram. The effective weight is governed by the well-known principle of Fig. 97. — Box of Analytic Weights. ANALYTIC APPARATUS. 685 the lever, namely, that the force exerted by any weight is directly pro- portional to its distance from the fulcrum. As each side of the beam is divided into 10 equal parts, the weight of the rider at each division is the number of tenths it is from the centre : thus, at 5, its weight is equal to of a centigram, or 5 milligrams, and so for each graduation and intermediate fraction. The employment of the rider in actual weighing will be gathered from the next paragraph. 771. Operation of Weighing. — In performing this operation, let it be supposed that the student has balance and weights in readiness, and requires to obtain the weight of some particular piece of apparatus ; this, whatever it is, must be thoroughly cleaned and dried, and then placed on the left- hand pan of the balance. For this purpose the front of the case of the balance may be raised, or if working with a balance with side-doors, that on the left hand may be opened. Two rules of weighing are : 1st, always place substance in left-hand pan, and weights in the right ; 2nd, keep the doors of the balance case closed whenever possible. Let the weight of the piece of apparatus in question, say a crucible, be 17*8954 grams ; by the following method this figure will have been ascertained. First take the 20 gram weight from the box by means of the forceps, and place it in the right-hand pan, release the beam from its support by turning the milled head : notice whether the left or right-hand pan of the balance is the heavier. In this case the weight will be too much, and the^index finger will swing to the left. Bring the balance to rest by turning the milled head, and take out the 20 gram weight, and replace it by the 10 gram, try whether sufficient — not enough, add 5 grams — still too little, add 2 — too little, add I — too much. Do not forget that every time before a weight is added or removed the beam must be brought to rest on its supports ; this is always to be done gently and carefully. After the addition of each weight the beam will have swung over more slowly ; with the 18 grams in the pan the swing of the index to the left will have been much slower than any preceding it, showing that the actual weight of the crucible is being closely approached. Return the 1 gram weight to its place in the box, and next try 0*5 gram — not enough, add 0*2 — not enough, add 0*1 — not enough, add 0*1 — too much. Replace the 0*1 and try 0*05 — not enough, add 0*02 — not enough, add 0*01 — not enough, add 0*01 — not enough. The weight has now been ascertained within a centigram, because the addition of another centigram would bring the weight up to the 0*1 gram, which has already been tried and found too much. The conclusion of the weighing should now be done with the rider. Place the rider on the 5 on the right-hand end of the beam, lower the sup- ports, cause the beam to vibrate, and shut the door of the case. If necessary, waft with the hand^a gentle current of air on to one of the pans in order to set the beam in motion. Count the number of graduations which the index moves on either side of the zero ; it will be found to vibrate slightly more to the right than to the left. Next try the rider on the 6th division ; this is found too much. Try the rider at intermediate distances until it is found that the beam swings through an equal number of graduations on either side of the zero scale ; the weight in each pan is then the same. Let us now see how the weights are to be read ; this should be done from the box, reading the empty spaces. In the case in point these are 10 + 5 + 2 = 17. Against “ weight of crucible,"" write this number in the note book. Next read off the decigram weights ; there are empty, 0*5 + 0*2 + 0*1 = 0*8 ; write *8 after the 17. The centigrams come next, they are 0*05 + 0*02 + 0*01 + 0*01 =0*09 ; WTite 9 after the 8. The milligrams and fractions of a milligram are to read off from the rider ; in the present instance the 686 THE TECHNOLOGY OF BREAD-MAKING rider stands at 0*0054 grams, 54 must therefore be written after the 9. The whole figure will then read : — “Weight of crucible = 17*8954 grams.” Having thus read the weight from the empty spaces in the box, next take the weights out and check the reading off as they are returned to their places. This double reading greatly reduces the chances of error in record- ing the weight of the substance. After a little experience in weighing, and thus getting to know the capacity of the particular balance used, the student should test his balance in order to ascertain the value of each graduation of the index scale. To do this put the rider on the 5 milligram mark, cause the beam to vibrate, and notice how far on either side of the zero it swings. Alter the position of the rider until the beam swings from the zero to the 10 on the one side ; note the position of the rider. Suppose it to be on the 5, then 10 divisions of the index scale = 5 milligrams, and 1 division = 0*5 milli- gram. This value will only b be approximately the same when the pans are loaded, but still sufficiently near to save time in the weighing. Thus, suppose 3*5 grams have been placed in the'pan, and the index vibrate 10 to the right and 8 to the left, there is no need to success- ively try the 0*2 and other weights down to the 0*01, but the rider may at once be put on the 1 milligram mark, and will be found to be very nearly in its right place. One or two trials v'ill then find the exact weight. The 1 is found in this case by taking half the difference between the vibrations on each side ; this will often apply, even Fig. 98. — Vabious Measubing Appabatus. tnougn the balance does not swing quite to the ten ; thus, the distances indicated might be 9 and 7. The beam should, however, be always caused to swing freely, as it makes a long oscillation in the same time as a short one. It will be noticed that, so far, the right- hand side only of the rider scale has been referred to ; the left is also fre- quently convenient. Supposing that, with the 3*5 grams just mentioned, tlie index had vibrated the tw'o extra degrees to the left, this would have indicated that the substance weighed about 1 milligram less than 3*5 ; to ])ut this weight in w'ould require the removal of the 0*5, and the placing of tlie 0*2, 0*1, 0*1, 0*05, 0*02, 0*01, 0*01, on the pan, and the rider at the 9 milli- gram mark. The same result is produced by placing the rider on the 1 milli- gram mark to the left. When the rider is on the left side of the beam, the weight it represents must be subtracted from that in the right-hand pan. Tlie operation of weighing has been described at full length, because it is the foundation of all quantitative analysis ; these operations are, how- ANALYTIC APPARATUS. 687 ever, mucli shorter in practice than they appear on paper. The genuine chemical student will never forget that his balance should be carefully, intelligently, and even lovingly used. In addition to the two balances and set of weights already described, the student will need another set of weights, ranging from 10 milligrams to 200 grams. 772. Apparatus Employed for Measuring Purposes. — These include measuring flasks, burettes, and other appliances. 773. Burettes and Floats. — Fig. 98, on page 686, is an illustration of various forms of measuring apparatus. The instrument marked a is termed a burette, and is used for the purpose of accurately measuring small quan- tities of liquid when delivered. There is at the bottom a glass stop-cock ; the tube is graduated throughout. The most useful size of burette is that holding 50 c.c. ; such an instrument is graduated in 500 divisions ; these are numbered at each c.c., from the top downwards. In using the burette it is first cleaned, and then rinsed with a little of the solution with which it is to be filled, then filled up almost to the top. When a long and na,rrow tube, such as a burette, con- tains a liquid, the top is not exactly level, but is always shghtly curved, with, in the case of water and aqueous solutions, the concave surface upwards. It is customary, in comparing the height of a liquid with the graduation marks, to read from the bottom of this curve, or “ meniscus,’" as it is termed. The next thing is to run the liquid out through the stop -cock until the zero mark is reached. Fix the burette upright in the burette stand, and place the eye level with the zero gradua- tion, then turn the stop-cock carefully, and let the liquid run out until the bottom of the meniscus exactly coincides with the zero line. The bur- ette is generally used for the purpose of running a liquid change takes place, then the is again read ofi, and the Erdmann’s Float. Burette, with Spring Clip. into a solution until some particular height of the reagent in the burette quantity that has been used determined. So when the change, whatever it may be, is complete, again bring the eye level with the bottom of the meniscus, and read ofi the graduation with which it coincides. Accurate reading of the burette is much assisted by the use of “ Erdmann’s Float ” ; this little piece of apparatus, which is shewn on this page (Fig. 99), consists of a piece of glass tubing of such a size as to be able to slide readily up and down within the burette. The tube is closed at both ends, so as to form an elongated glass bulb, which contains a small quantity of mercury. Around the float a single line, a, is marked with a diamond. When using the float it is dropped in the burette, and the line around it brought to agree with the zero mark at starting, and after- wards the height is read from the line on the float. A form of burette very 688 THE TECHNOLOGY OF BREAD-MAKING. convenient for general use is that known as Mohr’s ; it differs slightly in shape from that figured in the preceding illustration. Mohr’s burette is made either with a glass stop-cock, or else with a glass jet fastened on with a piece of india-rubber tubing, as shown in Fig. 100. A strong spring com- presses the tubing, and so stops the burette. The flow of the hquid is regu- lated by means of pressing the two buttons, shown, between the finger and thumb. The figure shows only just the lower end of the burette. The glass stop-cocks of burettes and other instruments should always be slightly greased, so as to prevent their sticking. If a burette is likely to be put aside for some time, it is well to withdraw the stop-cock altogether, and put it away separately, or a small slip of paper may be inserted between the plug of the stop-cock and its casing. 774. Pipettes. — Turning once more to Fig. 98, there are two instru- ments marked h, h ; these are pipettes, and are used for delivering a definite volume of any liquid ; the capacity of the two figured is respectively 50 and 100 c.c. In the tube just above the bulb there is a mark (not shown in the figure), which indicates the point to which the pipette must be filled. When using the instrument, place the lower end in the liquid to be meas- ured, and suck at the upper until the liquid rises above the graduation mark, then stop the upper end with the tongue ; next quickly substitute the tip of the finger for the tongue, without allowing the liquid to run out. This requires some little practice, but repeated trials overcome any difficulty at first experienced. Next raise the finger very slightly until the liquid begins to run from the lower end ; let it do so until the bottom of the menis- cus coincides with the graduation mark, then hold the end of the pipette over the vessel into which the liquid is to be poured, take away the finger and let the tube drain. When the highest degree of accuracy is required, the pipette should always be emptied in precisely the same manner. A good uniform method consists in holding the pipette vertical and allowing it to discharge its contents by gravity. When the main stream has stopped, hold the instrument in the same position until three drops have fallen, and then remove it. The pipette, if correctly graduated, will thus deliver the exact amount of liquid marked on it. The following are convenient sizes for pipettes : 2, 5, 10, 20, 25, 50, and 100 c.c. One 10 c.c. pipette will be required graduated throughout its whole length, somewhat like a burette ; it is, in fact, used for very much the same purpose. 775. Measuring Flasks. — The only other piece of apparatus that need be explained at present is the graduated flask, d, Fig. 98 ; this has also a mark round the neck showing the graduation line. The same remarks apply to its use as those already made in reference to the other pieces of measuring apparatus. Other pieces of apparatus required, with the methods of using them, will be described as occasion for their employment arises. CHAPTER XXVI. COMMERCIAL TESTING OF WHEATS AND FLOURS. 776. Wheat Testing. — ^The simplest and most direct commercial tests that can be made on whole wheat are its weight per bushel, weight of 100 grains of average size, and percentage of foreign seeds, dirt or other extraneous matter. Other tests are best made on the finely-powdered whole meal of the grain. 777. Weight per Bushel. — ^This operation is so famihar to all millers that an explanation of it is scarcely necessary. As is well known, there is a special piece of apparatus sold that is made for the purpose. A cheap and efficient substitute for this may easily be prepared and used where a student has such a balance as the coarser one previously described. Get a coppersmith to make a cylindrical measure about 3 in. in diameter and 3 in. deep. Procure from a dealer in chemical apparatus a counter- poise box ; these are brass boxes with lids which screw on. Put the empty measure on the one side of the balance and the counterpoise on the other, fill with shot until it exactly balances the measure. Next fill the measure exactly full of distilled water, level with the brim, and again weigh, always placing the counterpoise on the weight pan. The weight in grams of the water held by the measure represents its capacity in c.c. Now the weight of a bushel of water (= 80 lbs.), and that of the water contained in the little vessel, are always constant ; and, as the weight of the water the vessel contains is to the weight of the wheat that is being tested, so is the weight in pounds of a bushel of water to that in pounds of a bushel of the wheat. Expressing this in the usual way we have — As weight of water held by vessel : weight of wheat held : ; 80 : lbs. per bushel ; or X weight of wheat held weight of wheat in weight of water held pounds per bushel. Now for any particular vessel the weight of water it holds is always constant, so that 80 in the upper line, and the weight of water in the lower, may be reduced to a single factor, and the weight in pounds per bushel at once determined by multiplying the weight of grain, held in the measure, by that factor. Suppose that the capacity of the vessel is 200 c.c., then 80 =0-4 is the factor, and the weight of wheat in grams held by the vessel would simply have to be multiplied by that figure. In taking weights per bushel the little measure should be carefully filled, and then struck level by means of a pencil or other round piece of wood. 778. Weight of 100 Grains . — For this estimation it is important that the grains selected shall represent the average sample : if they are simply picked up one by one out of a heap, the weight is almost certain to be in excess of the true average ; for a person under these circumstances almost invariably unconsciously selects the largest grains. To obviate this, fold a strip of paper so as to form a V-shaped gutter ; take a handful of the 690 THE TECHNOLOGY OF BREAD-MAKING wheat and let it pour in a small stream along the length of this gutter. Then commence at the one end and count off the 100 grains, taking each as it comes. Weigh on the pan of the balance and enter the weight in the note-book. 779. Percentage of Foreign Matter. — The foreign matter in a sample of wheat may consist of other seeds, or possibly dirt or stony substances. Wliere it is only the former, a portion of the grain may be weighed off, and foreign seeds separated by hand-picking, and again weighing. The methods adopted for the removal of dirt must depend on the character of that present in the particular sample. Light, dusty, non-adherent matter may be removed by sifting or winnowing by means of an air current, and then weighing the residual grain. Adherent dirt will probably require washing of the wheat, and with this operation, the absorption of water by the grain comes in as a disturbing factor, for which provision must be made. The following is a convenient method of estimating dirt by the process of washing. From a fair sample of the wheat a convenient quantity is weighed off for the estimation ; 20 grams is usually a good workable quantity. A duplicate 20 grams is weighed off and placed in the hot- water oven in order to determine moisture (see subsequent paragraph 782). The lot to be washed is put in a wide-mouthed bottle, and shaken up with water ; the water is then poured on a fine sieve. This operation is repeated until the grain is clean. The wheat is then poured on to the sieve and examined in order to see whether there are any pieces of stone or other matter which ought to be picked out. Finally the drained wheat is trans- ferred to a dish and also placed in the hot-water oven. Both it and the portion for moisture determination are allowed to remain until the weight is constant (say over the night), which is then noted. The difference between the two figures is the amount of dirt removed by washing. An example will make this clear. Wheat taken for moisture, 20 grams; Weight after drying . . 17-54 grams. Wheat taken for washing, 20 grams ; Weight after washing and drying .. 16-06 „ Weight of dirt removed .. 1-48 „ Multiply by . . 5 Amount of dirt in samples . . 7-40 per cent, 780. Grinding of Samples. — The fine whole meal for other determina- tions is best obtained by passing the wheat through a combined grinding and cutting mill, of which a very convenient form is that known as the “ Enterprise drug mill. An ordinary coffee mill might answer the purpose, but most likely would not cut up the bran sufficiently fine. The process adopted is as follows : — The mill is set as fine as it will run without clogging. (It need scarcely be mentioned that every part must first be thoroughly cleaned.) The wheat is then poured in the hopper and run through as rapidly as possible. The grist is next put into a fine sieve, about 20 or 24 meshes to the inch, and sifted. The bran is returned to the mill, and run through and again sifted ; this operation is repeated on the coarser particles until the whole of the meal has been thus sifted. Care must again be taken at the end to clean every particle out of the mill and add it to the meal ; this is essential, because the latter particles are more branny than the former. The meal is next stirred up thoroughly, and then stored in a tightly corked or stoppered bottle. In this way a whole meal is obtained. COMMERCIAL TESTING OF WHEATS AND FLOURS. 691 which of necessity is an exact representative of the grain. It may be asked whether the wheat should be cleaned in any way previous to grinding for analysis. The answer to such a question is that this must depend on the purpose for which the analysis is required. An analysis made for the purpose of buying or selling by should be performed on a sample representing the bulk of the parcel of grain in question ; it should therefore be in no way cleaned or washed. When a miller requires to know the analytic character of a variety of wheat in the cleaned state, the analysis would obviously be made on the sample after cleaning. Undoubtedly the safest plan is to analyse the sample exactly as collected, unless the analysis is made for some special purpose. If a clean wheat is analysed the weight of cleaned wheat obtained from a definite weight of the uncleaned wheat should first be ascertained. 781. Experimental Test Mills. — The best general mode of testing wheats is that of first reducing the same to flour, and then testing the flour. With this end in view, the larger mills are frequently fitted with small reduction plants by which an experimental quantity of wheat may be reduced to flour, and this tested before the whole of the wheat is ground. The plant for this purpose may be of various sizes, from a fairly complete small roller mill installation to a specially made machine for reducing purposes, the different separations being made by hand. In this connexion see the description of Tattersall’s special milling plant in Chapter XX XII on Routine Mill Tests. On the flour thus obtained, determinations may be made of such kinds as are employed on flour produced during the ordinary course of manufacture. It does not follow that the experimentally-made flour will be equal in every respect to that obtained in practice on the larger scale; but usually the results are sufficiently nearly comparative with each other to afford valuable information. The practical miller will naturally make allowances for the milling peculiarities of the wheats he may be thus examining. With a mill of this kind, the percentage yield of straight flour, bran, and other offal, obtainable from each particular sample of wheat may be determined. 782. Moisture Determinations.— These may be made either on the ground meal from grain or the dressed flour. They are sometimes made on the whole wheat, but with this there is the objection that the unbroken grains lose moisture somewhat slowly. In view of the wide extension of the use of conditioning and analogous appliances and processes in modern milling, a check on the moisture of the wheat and also on the flour, bran, and other products has become of considerable importance. The percentage of water or moisture is usually found by weighing out a definite quantity of the flour or meal in a small dish, and then drying in the water oven until it no longer loses weight. When a number of samples have to be assayed, some regular method of procedure is necessary. The following method may be adopted : — Procure from the apparatus dealer one dozen selected glass dishes, 2^ in. diameter. Mark these with the numbers 1 to 12 on the sides with a vTiting diamond. Have a little box made in which to keep these dishes. The box should have a shelf, supported a little way from the bottom, containing a series of separate holes, one for each dish, so that they may be kept without danger of breakage. Clean and dry each dish, and then weigh it carefully ; enter the weights in the note-book, and, previous to using each dish, test its weight. This may be done very quickly, as the weights are already approximately known. It will be found that, if msed with care, the weight of the dishes will remain constant, within 692 THE TECHNOLOGY OF BREAD-MAKING. some four or five milligrams, for a considerable time. Time may be still further economised by having a series of counterpoises made for the set of dishes. These consist of little brass boxes in the shape of weights, the tops of which can be unscrewed. Brass counterpoises of this description can be readily obtained. Have engraved on the top of the counterpoises a series of numbers corresponding to those on the dishes ; clean the counter- poises and dishes thoroughly, and balance the one against the other in the following manner : — Place No. 1 dish in the left-hand balance pan, and the corresponding counterpoise in the other, together with its cover. Fill up the counterpoise with shot until it is as nearly as possible of the same weight as the dish, then add little shreds of tinfoil until the two exactly counter- balance each other ; finally screw the lid and box part of the counterpoise together. Proceed in exactly the same way with all the dishes. In this case the shelf of the box for the dishes should also have little holes cut in it for the counterpoises, so that each may be kept immediately in front of its particular dish. Having a set of counterpoises, before using each dish test it on the balance against its counterpoise, and if necessary adjust the weight with the rider. As the dishes gradually become lighter through use, the rider will have to be placed on the left-hand or dish side of the balance. In case the balance is one which is only fitted, with the rider arrangement on the right-hand side, the dish may, if wished, be placed on that side, and the weights on the left in weighing ; this, however, is liable to lead to confusion and mistakes in reading the weights. As the dishes grow lighter, their weight against the counterpoise is really a minus quantity, and should be entered as such in the note-book. For a long time the difference between the two is inappreciable, but still, for the sake of accuracy, the test should always be made. When the dish and counterpoise differ more than -005 gram, the latter should be readjusted. Having a number of determinations to make, weigh out exactly 10 grams of each flour in a dish, then place them in the hot-water oven and allow them to dry for 24 hours ; at the end of that time the water will be expelled. Take out the dishes, allow them to cool in a desiccator, and weigh as quickly as possible. As the weight of each is approximately known, put the larger weights on the balance pan before taking the dish from the desiccator. After weighing, return the dishes to the oven for another hour, and again weigh ; the two weighings should agree within a milligram. Dry flour is very hygroscopic ; that is, it absorbs moisture with great rapidity. This is noticeable during weighing, for a sample will often gain while in the balance as much as five milligrams. The student will at first, for this reason, get his weights too high. The best plan is to put on the rider at a point judged to be too high, and then at each trial bring it to a lower number until it is found to be at one at which the dish is the heavier. Then take the lowest figure known to be above the weight of the dish, for if the rider now be moved upwards, the dish will often be found to gain in weight just as rapidly as the rider is moved upward. Before the dish is removed from the desiccator for the second weighing, put in the pan the lowest weights before found to be too heavy. After a time the student will find that he can get his two weighings to always practically agree ; he may then, but not till then, dispense with the second weighing. It is evident that the flour after being deprived of its moisture will weigh less ; the weight taken, therefore, less the weight of dried flour, equals the moisture ; this, when 10 grams are employed, multiplied by 10 gives the percentage. There are now made flat porcelain numbered dishes for milk analysis, and these may if wished be used instead of glass dishes for moisture deter- minations. Another convenient form of dish is that of pohshed nickel made in tlie flat shape ; these latter possess the advantage of being unbreakable. CO]\LMERCIAL TESTING OF WHEATS AND FLOURS. 693 Fig. 101. — Hot-Water Oven. 783. Hot-Water Oven. — These ovens are usually made of copper, and are of the appearance and shape shown in Fig. 101. The oven consists of an inner and outer casing, with a space between them about an inch in thickness ; the top, bottom, two sides, and back, are therefore double. This space for about half the height of the oven is, when in use, filled with water, which is kept boiling by a bunsen flame placed underneath. Anything placed in the oven is thus kept at a temperature of from 96-100 ° C., but, while there is any water within the casing, never above the latter temperature. In order to prevent the oven boiling dry, a little feed apparatus is a con- venient attachment. This usually consists of a copper vessel open at the top, and communicating by means of a pipe with the water space of the oven. Through the bottom of this vessel is passed a piece of glass tubing, the top of which reaches to the height at which it is desired that the water shall re- main in the oven. This glass tubing is kept in its place by a piece of india-rubber tubing, which, while making a water-tight joint, allows the tube to be slidden up or down as wished. A small stream of water is led into the feed apparatus ; this feeds the oven, and the overflow passes out through the glass tube, which should either stand over, or be led into, a drain. Another very good plan is to have fitted to the top of the water oven an inverted Liebig’s condenser, through the outer casing of which a stream of cold water is passed. The steam from the boiling water in the casing is then condensed by the condenser, and returned to the oven. The oven, having been once filled, will not need replenishing for a considerable time, as the loss of water is very little. The condenser should be made of brass or copper tubing ; the inner tube about f in. in diameter, and the outer IJ in. : the length should be from 24 to 30 in. The cold water should enter the jacket at the bottom. When a condenser is used, the oven should also be fitted with a glass water guage, to indicate the height of the water as shown in the figure. With this arrangement the oven may be filled with distilled water, and so loss of heat by the formation of crust be pre- vented. Where time is an object, it is convenient to use an oil oven instead of one filled with hot water. The oven is similar in construction, but the jacket is filled with oil, and the temperature raised for wheat or flour drying to 105-110° C., being regulatedlby adjusting the burner, or by means of an automatic regulator. ^784. Vacuum Oven. — In estimations of moisture for milling purposes, speed is almost always of the utmost importance ; the authors have there- fore designed and used with success a special form of vacuum oven for such determinations. The oven. Fig. 102, is of circular shape with fiat bottom, and consists of an inner casing, a, a, and an outer jacket 6, h, of copper. The diameter of a, a, may be from 10 to 12 in., and the internal height about 5 in. The space between the casing and jacket should be not less than 1 in. At c is attached a small water guage. A return 694 THE TECHNOLOGY OF BREAD-MAKING. condenser is fixed as shown at d, d. By means of a burner fixed under the oven the temperature of the water in the jacket is maintained at 100° C. Or if wished, a solution of potassium carbonate may be employed ; this boils at a temperature above 100° C. and depending on the degree of con- centration of the solution. A drawback is that the salt slowly attacks the metal of the oven. Or an organic liquid such as toluol, boiling at 107° C., may be used. With this, however, care must be taken as the boiling liquid is inflammable. The advantage of the higher temperature is the more rapid drying capacity of the oven. At e is fixed a pipe leading to a Korting or other efficient vacuum pump. The open end at e is turned up so as to prevent the inrush of air from impinging on the contents of dishes in the oven. At / a tap is placed, by which air can be admitted into the oven ; on the opposite side / is shown a small Bourdon vacuum gauge. The upper part of the oven is drawn into an opening about 6 in. internal diameter, terminating in a flange the face of which is turned and ground perfectly true at h. On this rests a gun-metal lid, i, also faced true. At j, j, are hinged screw clamps by which the lid is securely screwed down to make an air-tight joint with the upper flange of the oven. In use the oven is made hot by a burner arranged underneath, preferably of the ring COMMERCIAL TESTING OF WHEATS AND FLOURS. • 695 type. Flat nickel dishes are most suitable for the flours or meals. These are placed in the oven and then the lid is fixed in position. In order to make the joint, the faces of the flanges are smeared with a luting mixture of asphalt um and paraffin, or a rubber ring may be used. In this latter case the ring and the faces of the flanges should be well blackleaded. The top at / is closed and the vacuum pump started, and kept at work so as to maintain a good vacuum as shown by the gauge. Drying is exceedingly rapid and thorough with the flat dishes in immediate contact with the flat bottom of the oven. The minimum time for complete drying should be ascertained by an actual test ; after which, provided the vacuum is kept up, the dishes with their contents may simply be dried for the requisite time and then weighed. To reopen the oven the pump is turned off, and then the tap / carefully opened to admit air. The clamps are then unscrewed and the lid slid off. 785. Rapid Determinations of Moisture. — The following method has been recommended by Parsons for obtaining rapid determinations of moisture. The principal requisite is a perfectly neutral petroleum oil, free from animal or vegetable oils and mineral substances, and having the following constant — Sp. gr., 0-920 ; flash test, 224° ; boiling point, about 288°. This oil is heated to about 120° for some time and then kept in a well- stoppered bottle. The object of this treatment is to secure a liquid of neutral character and free from any matter which is volatile up to the temperature of 120°. In making an estimation, a quantity of oil about six times the weight of the substance to be dried is heated in a basin or dish in a drying oven at a temperature of 115° and then weighed. In meal and flour determinations, convenient quantities would be 5 grams of the meal and about 30 grams of the oil. A small glass rod may also be conveniently weighed with the dish and oil. The weighed portion of the substance is then added to the oil and stirred in. There will be usually a slight effervescence ; when this is over the dish should be placed in the drying oven for a short time and weighed ; the loss is moisture. It is stated that the whole operation may be completed in less than half an hour, 786. Moisture by Distillation Processes. — Apparatus has been devised by which the water driven off from grain or its products by means of a hot oil bath is collected and measured, thus serving as a means of determination of moisture. A weighed quantity of the wheat or other grain is placed in a proper receptacle, and covered with moisture-free oil. This vessel has a tube leading therefrom to a condenser, from which any liquid escaping is received in a tall graduated measure. The vessel is enclosed in a jacket and is fitted with thermometers so as to measure the temperature to which it is to be subjected. On heating to about 110° C. the whole of the moisture of the grain is driven off, condensed by the condenser, and collected in the measuring vessel. This latter is so graduated as to allow the amount of condensed water to be at once read off in percentages without any calcula- tion. The estimations can be rapidly made, and a fairly large quantity of material is taken for each test ; both these are of advantage in an apparatus commercially worked in a mill. 787. Effect of Humidity of Air on Moisture of Flour. — Flour is exceedingly hygroscopic and absorbs or loses moisture, according to whether the atmo- sphere is damp or dry, with great readiness. Richardson examined a series of flours immediately on coming from the mill, and again after being exposed to the atmosphere for a day, with the following results : — 696 THE TECHNOLOGY OF BREAD-MAKING. No. Original Moisture. 9-48 7-80 7-85 7-97 13-69 Gain or Loss. +0-65 +2-15 +2-30 +2-15 -3-28 Second Day. 10-13 9-95 10-15 10-12 10-41 It wdU be seen that, notwithstanding the wide differences in percentage of moisture on the first day, they had, at the end of the second, become practically equalised. Richardson next allowed these fiours to remain exposed to the atmosphere for 16 days, making during that period 15 deter- minations of moisture. In one and the same flour during that time varia- tions of nearly 5 per cent, were observed. In the following table the results are expressed in weight in lbs., which 100 lbs. of the original flour would have assumed under the conditions ; — Xo. ». 1. Original Weight. 100 lbs. Original Moisture. 9-48 Highest Weight during 16 Days. 102-88 lbs. Lowest Weight during 16 Days. 99-53 lbs. Amount'of Variation. 3-35 lbs. 2. 100 „ 7-80 104-87 „ 100-00 „ 4-87 „ 3. 100 „ 7-85 105-20 „ 100-00 „ 5-20 „ 4. 100 „ 7-97 105-95 „ 100-00 „ 5-95 „ 5. 100 „ 13-69 100-00 „ 95-35 „ 4-65 „ No. 1 of these flours was the well-known brand, Pillsbury’s Best ; it will be of interest to give the weight of this each time determined, and also the relative humidity of the air each day. Date. March 7 . . Weight of Flour. 100-00 lbs. Relative Humidity of Air. Date. March 17 Weight of Flour. 100-38 lbs. Relative Humidity of Air. 42-2 „ 8 .. 100-65 „ 46-4 „ 18 .. 101-88 „ 59-5 „ 10 . . 99-53 „ 35-0 „ 19 .. 102-03 „ 60-1 „ 11 .. 101-73 „ 59-0 „ 20 .. 102-48 „ 55-6 „ 12 .. 102-68 „ 60-1 „ 21 .. 101-43 „ 51-8 „ 13 .. 99-88 „ 34-0 „ 22 . . 101-68 „ 51-1 „ 14 . . 101-08 „ — „ 24 . . 102-88 „ 66-9 „ 15 .. 101-53 „ 48-2 It will be observed that with an increased dampness of the air, the weight of the flour is also increased. Of course, in strictness, the weight of the flour is governed by the degree of humidity prior to the moisture determination, rather than that at the time the determination is actually made. On exposing a sample of patent flour to an atmosphere kept absolutely saturated with water, it absorbed more than 26 per cent, of its original 'weight in 64 hours. The following table gives the weight at different intervals : — Weight of flour taken . . . . . . . . 1-0000 grams, after 35 minutes . . . . . . 1-0285 ,, 18 hours. . 22 „ . . 42 „ . . 64 „ 1-0930 1-2005 1-2405 1-2670 These variations in weight of which flour is capable go far toward explain- ing discrepancies in water-absorbing power, and yield, of laboratory samples. 788. Gluten Determinations. — The strength of flour has been amply dis- cussed in a previous chapter, in which it is shown that it largely depends COMMERCIAL TESTING OF WHEATS AND FLOURS. 697 on the quantity and character of the insoluble proteins contained in the flour. In a crude form these are obtained in the well-known washing pro- cess for gluten. One great objection to the gluten test is the difficulty of knowing precisely when the whole of the starch has been removed, and then stopping short of washing away any of the gluten itself. In many flours the gluten begins to disintegrate and wash away before the whole of the starch disappears. With some little experience the same worker can get concordant results, but this is not invariably the case with two workers testing against each other ; one will then frequently throughout a whole series uniformly get higher results than the other. As, therefore, consider- able differences may exist in the percentages of crude gluten obtained, both in the wet and dry state, it is recommended that in addition the “ true gluten or protein matter be also determined by a direct nitrogen estima- tion, Even when there are marked discrepancies in the crude gluten as obtained by washing, the true gluten varies only within comparatively narrow limits. J As an index of strength, it is recommended that the following estimations be made ; — Percentage of gluten wet and dry by the washing-out process, and of true gluten by nitrogen determination on the dry gluten ; all of these to be calculated on the whole flour. Appearance and physical character of the gluten to be noted. Percentage of total proteins in the whole flour. 789. Gluten Extraction. — One of the most important points is that a uniform method is always adopted. The following is a very convenient mode of working. Thirty grams of the flour should be accurately weighed and transferred to one of Pfleiderer’s small doughing machines (made especially for the purpose). To this should be added in the machine 15 cubic centimetres (=15 grams) of water from a graduated pipette. The whole should then be thoroughly kneaded, receiving 100 revolutions by the counter after the flour and water are first roughly mixed. (While the machine is exceedingly convenient, the dough may as an alternative be made by hand.) From the resultant dough one or two portions of exactly 15 grams each should be accurately weighed and then transferred to a small glass containing sufficient cold water to keep them entirely submerged in which they must be fetllowed to remain for exactly an hour (The second piece is only to be weighed off in event of a duplicate being required.) The weighed portion of dough contains exactly 10 grams of flour, and should be washed in the following manner : — Prepare some water at a temperature between 70° and 80° F., and partially fill a clean bowl with same. For reasons before given the water must be ordinary tap water, and not distilled water. Wash the lump of dough by kneading it gently between the fingers in the water, using no muslin or other enclosing substance. The starch is gradually washed away, and the remaining dough acquires the consistency and characteristic feel of gluten. Take care that no fragments are washed ofl the main lump ; and after the gluten is approximately freed from starch, place it aside on a clean surface of glass or porcelain : let the washing water settle, and decant it very carefully through a fine hair sieve. Should there be any fragments of gluten on the sieve, pick them up with the main piece and do the same with any remaining in the basin. Take some more of the tepid water and repeat the washing some little time longer ; change the water about two or three times, with the same precaution against loss as before. The last washing water should remain almost clean. The gluten may now be taken as pure, freed as far as possible from adherent moisture and weighed. In the case of Hungarian and certain other flours of very high water- absorbing power, it is sometimes advisable to make a slacker dough for 698 THE TECHNOLOGY OF BREAD-MAKING. gluten extraction than that just described. For this purpose add 20 c.c. of water to the 30 grams of flour, and take 16-66 grams of the dough for each estimation. This weight contains, as before, exactly 10 grams of flour. If preferred, 10 or 20 grams of flour may be weighed off and made up into a dough with water direct for this estimation.) When it is intended to determine the gliadin in the gluten, 30 or 33-33 grams of dough should be taken for washing purposes instead of 15 or 16-66 grams. The washing operation should be conducted as before. The whole mass of gluten is then weighed and registered as wet gluten, after which it is separated into two halves by weight. One is dried for dry gluten, and the other is used for the gliadin estimation (see paragraph 854.) For the drying of the gluten, pieces of paper should be prepared before- hand in the following manner : — Take a sheet of cartridge or other stout paper and cut it up into small pieces 3 inches square. Place these in the hot- water oven and dry at 212° F. for two days. Take them out and allow to cool in a desiccator, and weigh them off rapidly to within a decigram. Mark the weight in pencil on the top left-hand corner of the paper. Keep a store of these in a clean box. If preferred, these may be obtained ready cut from a printer. They will then be found to be of just the same weight ; and if two pieces be equally dried in the hot-water oven they mil still counter- balance each other. This should be verified by an actual trial. Wlien any number of glutens are being simultaneously determined, a blank piece of paper may be put in the oven with the glutens, and used throughout as a counterpoise when weighing them. If for any reason special accuracy is required, the paper should in each case be dried and weighed for each estima- tion. Having weighed the gluten as above described, mould it between the fingers and notice its physical condition, whether tough and elastic, soft and flabby, or “ short ” and friable. Make a note of same. Mould it into a ball and place it on the centre of one of the weighed papers. On the one corner mark the date, and below, the name or number of the flour, with the v'eight of the wet gluten. Next place the gluten in the hot-water oven and dry at 212° F. until the weight is constant ; then weigh to the decigram, subtract the weight of the paper, or weigh against the counterpoise piece, and express the result in percentages. The gluten adheres to the paper, and thus may be kept as a record of the flour. To determine the true gluten, break up the crude dry gluten into coarse fragments, and estimate nitrogen by the Kjeldahl method, as described in Chapter XXVIII. The percentage of true gluten should be returned on the whole flour, and should be at least 80 per cent, of the crude gluten. By means of the same process (Kjeldahl) determine the total proteins in the flour. 790. Extraction of Gluten from Wheat-Meal. — The meal may be weighed and made into a dough precisely as with flour ; or if wished, 10 or 20 grams only may be weighed off and transferred to a basin, and then mixed with sufficient water to make a somewhat slack dough. This is allowed to stand as before for one hour under water. Instead of washing the dough direct in the bowl, it is preferable to first enclose it in a piece of either fine muslin or, preferably, millers’ bolting silk. This must be held securely in order to prevent any loss of the dough, which must be held under water in the bowl and kneaded between the fingers until a fresh lot of water is no longer caused to become milky by the escaping starch. On opening the silk, it . will be found not only to contain the gluten, but also the bran of the wheat, and these have to be separated from each other. With the harder wheats tliis is done without much difficulty, but in the case of those that are softer COMMERCIAL TESTING OF WHEATS AND FLOURS. 699 it’is sometimes almost impossible to recover the whole of the gluten. After having washed out the starch, squeeze the water from the silk, and then open it out on a piece of glass. There will usually be one fairly sized lump of gluten ; take this out and rinse it moderately free from bran in a basin of clean water, next squeeze it well together, then pick off any tolerably large pieces of gluten that remain on the silk, and add them to the main lump. After each addition again squeeze the piece together and rinse off any loose bran. The difficulty is now to gather together any particles remaining in the bran — these are often so small as to be scarcely visible. Take the mass of tolerably clean gluten and add to it a portion of the bran, roll them together with considerable force between the palms, and then wash off the bran. Tills process of rubbing together the main lump of gluten and the bran effects the removal of any little fragments of gluten by their sticking to the larger piece ; which, in virtue of its adhesive property, picks them out from the bran, just as a magnet picks out iron filings from among those of brass. Treat the whole of the bran remaining on the silk in this manner ; the result will be a lump of gluten still containing a little bran. With a hard wheat, however, the whole of the gluten will have been thus recovered ; with the softer ones it is sometimes advisable to drain the water off the bran and again rub it all up with the gluten. In every case inspect the bran most carefully before throwing it away ; the bran should also be rubbed between the fingers ; this will often detect fragments of gluten that escape the eye. Having got the whole of the gluten together, wash it time after time until free from bran. This is a tedious operation, but one that can be performed by vigorous and careful treatment. Pour every lot of water on to the muslin in order to see that no gluten is lost. The washing must be continued until the gluten yields no turbidity to clean water. The subsequent processes are performed on the wheat gluten precisely as with that from flours. 791. Water- Absorbing Capacity. — One of the best methods of deter- mining the water-absorbing capacity of a sample of flour is by doughing it, and then judging by the consistency of the dough. The dough may be tested in this manner shortly after being made up, and again after an interval of some hours. A more or less accurate judgment is thus formed of the water-absorbing power of the flour when first made into dough, and also its capacity for resistance to the changes which take place in the constitu- ents of flour while standing for some time in a moist condition. The unfortunate point about such determinations is, that judging by the appear- ance and stiffness of a dough is exceedingly uncertain : one person’s own judgment is not at all times alike, and the difficulty is multiplied infinitely when an attempt is made to compare that of several persons. Again, there is the fact that for all purposes of exactitude it is essential that some means shall exist for expressing results in actual figures. Finding the problem in this state, one of the authors devised apparatus, which had as its object the determination of water-absorptive power, and giving a numerical expression of the result. The starting point was to decide on some mode of expressing yield : the first idea was to make use of the number of quartern loaves of bread that could be produced from a sack of flour. But here the difficulty occurred that different bakers are in the habit of weighing their bread into the oven at different weights, to say nothing about the possibilities of different weights when the bread leaves the oven. Further, the use or non-use of “ fruit ” renders this method of considerable uncertainty. There is again the fact that some bakers work with slacker doughs than do others. After considering several possible modes of expression, the decision 700 THE TECHNOLOGY OF BREAD-MAKING. arrived at by the authors was to give the quantity of water that a specific weight of the flour took, in order to produce a dough of definite and stand- ard consistency. By almost universal consent the standard of weight of flour would, in this country, be the sack of 280 lbs., while water can be conveniently expressed in quarts. The quart being the quarter of a gallon, and the gallon weighing 10 lbs., render it easy to convert quarts into either gallons or lbs. It will be noticed that the adoption of this standard does not touch on the contested question of loss of water in the oven. If preferred the tests may be made, and the results expressed in c.c. per 100 grams, i.e. parts per hundred. 792. Water-Absorption Burette. — The operation of doughing resolves itself into taking any convenient quantity of flour and adding sufficient water to it to make a dough of normal stiffness and then calculating out the water employed into the proportion of quarts per sack. The simplest way of doing this is to fix on the quantity of flour, and then make a measuring instrument for the water (“ burette "" or “ pipette ”), wffiich shall be graduated so that each division represents a quart of water per sack. Such a mea- suring instrument is the first part of the apparatus described ; in using it, the flour is weighed out, and the quantity of water run in is at once read off, without any cal- culation whatever, as quarts per sack. The practical advantages of this method are evi- dent, as from a small doughing test a baker can at once direct how much water is to be added per sack of any particular flour. The strength burette, together with the visco- meter, is shown in Fig. 104 : at the top of the instrument is the zero mark, between wiiich and “ 40 there are no graduations ; the tube is then graduated in single quarts down to 80 at the lower end. At the bottom a glass jet is attached by means of a piece of india-rubber tubing ; this is normally kept closed by the spring-clip, but may be opened at will by pressing the twn buttons shown, one on either side. In use, the bur- ette may be held in the hand, but is prefer- ably fixed in a burette stand. It may be filled either by pouring in w^ater at the top, or by opening the clip and sucking it up through the jet. It is important to bear in mind that if great exactness is required in doughing tests, the dougli, wiien made, should have a definite temperature. It is recommended that for this purpose that of 70° F. be adopted. If pos- sible, a flour- testing laboratory should stand permanently at as nearly as possible that temperature. Before starting a series of tests, the w^ater should be adjusted to 70° F. ; and the flours, if cold, allowed to stand in a warm room sufficiently long to give the same temperature wffien tested by Fig. 103 . — Burette, Arranged WITH Reservoir. the tliermometer. Wliere a number of flours are being tested, it is an exceedingly con- COMMERCIAL TESTING OF WHEATS AND FLOURS. 701 venient plan to have a water reservoir attached to the burette ; the whole apparatus will then appear as shown in Fig. 103. In the lower part of the figure the burette is seen fixed in a stand. At a is a second tube opening into the burette above the clip : by means of india-rubber tubing, this second tube, a, is attached to a glass reservoir. A, which stands on a shelf above the level of the top of the burette. By means of a spring-clip at a the liquid in the reservoir is shut off from the burette. The burette being empty, open the clip a ; the water flows from A upward into the burette ; when the level coincides with the zero mark close this clip, and proceed to deliver the desired quantity of water by pressing the clip at the bottom of the burette. In this manner the instrument may be filled with great convenience and rapidity. To test a flour, weigh out as exactly as possible one and a half ounces of the sample, and transfer it to a small cup or basin. Next fill the burette with water until the level exactly stands at the top graduation mark. Then place the cup containing the flour under the burette, and press the clip, allowing the water to run out until down to as many quarts as it is thought likely the flour will require. Then, by means of a stirring rod, or bone spa- tula, work the flour and water into a perfectly even dough ; try, by mould- ing it between the fingers, whether it is too stiff or too slack : if so, dough up a fresh sample, using either more or less water as the case may be. Hav- ing thus made a dough of a similar consistency to that usually employed, read off from the burette how much water has been used. The figures will express, without any further calculation whatever, how many quarts of water the flour will take to the sack. It is well before judging the stiffness of the dough to allow it to stand for some time. The authors allow their doughs to remain an hour before testing them. It is not safe to state from the doughing test alone how many loaves a certain flour is capable of yielding per sack, because different bakers, by working in different manners, do not get the same bread yield from one and the same flour. Each baker should therefore ascertain for himself by means of a baking test, working according to his own methods, how many loaves he obtains from a sack of any particular flour. He can then in the following manner arrange for himself a table showing the bread equivalent of the “ quarts per sack ” readings of the burette. To make this test, take a sack of flour and measure the quantity of water requisite to make a dough of the proper consistency. Then count the number of 2-lb. or 4-lb. loaves it yields on being baked. Suppose that the flour takes 70 quarts of water : then dough up a sample with the burette, using water to the 70 quart mark, and take dough of that stiffness as the standard. Any other flour of the same character which takes the same quantity of water to make a dough of similar consistency will turn out about the same yield of bread. Suppose another sample of flour takes 72 quarts of water, then it will make, neglect- ing the slight loss in working, 5 lbs. more dough (one quart of water weighs 2J lbs.). Weighing the bread into the oven at 4 lb. 6 oz. per the 4-lb. loaf, every two quarts more water per sack means rather over another 4-lb. loaf produced. In exact figures the additional 5 lbs. of dough yield 4 lbs. 9 oz. of baked bread, or practically 4J lbs. In this easy manner, by this instrument, a baker may determine for himself, without any but the simplest mental calculation, and working according to his own processes, how much bread a particular flour yields. It is advised that every baker should for himself construct a table of results, based on his own method of working. To do this, let him, as suggested, make a trial baking, and find out how many quarts of water a sack of any one flour takes, and how many loaves it produces. Enter those figures in the table, then for every two quarts more add on 4J lbs. of 702 THE TECHNOLOGY OF BREAD-MAKING. bread or 1| 4-lb. loaves : for- every two quarts less subtract the same amount. 793. The Viscometer. — In order to carry the water absorption problem a step further, it is necessary, not only to have made the dough, but also to devise means for mechanically determining its consistency. This is the more difficult, as different kinds of flour pro- duce doughs of different character. Thus, a spring American flour will yield a dough whose essential characteristic is rigidity ; a Hungarian flour yields a soft dough, but one which, nevertheless, possesses most remark- able tenacity. Any instrument for measuring the consistency of dough must take into ac- count these two somewhat opposite characters, giving each its proper value. The resistance of the dough to being squeezed, and its resist- ance to being pulled asunder, must both be taken into account. The second part of the flour-testing apparatus consists of an instru- ment for definitely measuring the viscosity of dough. This is effected by forcing a definite quantity of dough through a small aperture, and measuring the time taken in so doing, the force being constant. The machine for mak- ing this measurement is termed a “ Visco- meter,” literally, a measurer of viscosity. It is so arranged that, in doing the work of for- cing the dough through the aperture, both the stiffness and tenacity of the dough are called into play as resisting agents. The conse- quence is that a very soft and tenacious dough may prove its viscosity to be as great as that of a stiff dough with comparatively little tenacity. Undoubtedly this is in keeping with the observed facts of baking, for, as is often said, certain flours will bear being made much slacker than others ; that is, their tena- city as dough more than makes up for their comparatively little stiffness or rigidity. The viscometer consists essentially of a cylinder, having a weighted and graduated piston, and an aperture through the bottom for the exit of the dough ; the stiffer the dough, the more slowly does the piston de- scend. Since the first instrument was made a number of alterations and refinements have been introduced with the object of diminishing certain causes of error which were revealed on experiment. In its present form the instru- ment is affected in its worldng by the condition of the dough, and that only ; further, it takes cognizance both of the tenacity and the rigidity of the dough. It is claimed for the viscometer that it affords a means of absolute measure of these two qualities of stiffness and tenacity. In certain cases where two doughs have been submitted to the judgment of bakers, and Fig. 104. — Viscometer and Strength Burette. COMMERCIAL TESTING OF WHEATS AND FLOURS. 703 then tested by the viscometer, that judged the softer to the touch has been registered by the viscometer as the dough of greater consistency. The very simple explanation is that it is difficult to form an accurate judgment of tenacity by handling a small piece of dough. Flours which exhibit this particular combination of softness and tenacity are just those which bakers would say require to be worked slacker than others. Consequently, even in these instances, the viscometric measurement affords a valuable indication of the working water-absorbing capacity of the flour. Millers and bakers who have seen the apparatus at work endorse this opinion. In using the instrument, the dough is first put into the viscometer, and the time which the piston takes to travel between two of its graduations is noticed. Fig. 104 is a sectional drawing of the viscometer, about one-tliird the actual size of the instrument. The lower part, marked u &, is a cylindrical base, through which are two lightening holes, marked y z. The cylinder, e /, and flange, c d, are cast in one piece ; c d has a collar turned down to fit inside a b, the edge of c d is milled. Through the bottom of the cylinder is a hole, marked t ; the upper edge of this hole is rounded off, in order that no cutting edge shall be presented. This aperture may be opened or closed at will by the cover, u, which slides between a pair of guides, and may be drawn in or out by the rod and milled head, v. The piston, m n, consists of a disc of gun-metal, the lower edge of which is rounded : this piston is attached to the bottom of a trunk, m o, the diameter of whicli is about one-sixteenth of an inch less than that of the piston. This piston trunk passes through the cylinder cover, g h ; in the top of this cover is screwed a tube, i j, carrying at its upper end a collar, k 1. Both this collar and the cylinder cover, g h, are bored to exactly fit the trunk of the piston. The cylinder cover tube, i j, and collar, k I, therefore together act as a guide for the piston, allowing it to slide steadily up and down with the minimum of friction. The bottom of the cylinder cover fits over the top of the cylinder, and is secured in its place by a pair of studs and bayonet catches, s h. On the upper part of the trunk are three lines, pgr, the'distance between each pair being three-eighths of an inch. This trunk is loaded inside in order to give it the requisite weight. With the exception of the piston, m ii, the instrument is throughout constructed of brass. 794. Method Employed^ in using the Viscometer. — It is' first necessary to fix on a standard of stiffness for doughs : that adopted, by the authors is such as allows the piston of the viscometer to fall from mark p to mark r in 60 seconds. As such doughs are slacker than those employed for many purposes, a stiffer standard may, if wished, be selected ; in such a case the readings may be taken, if desired, when the piston has made half its stroke, that is, has travelled from r to q instead of the whole distance, r to p. Each individual user of the instrument may thus determine on a standard for himself. Wliatever standard is selected, whether the 60 -seconds" standard employed by the authors, or another, weigh out one and a half ounces of flour, add water from the strength burette, and dough up the sample as before described, using a quantity of water, which, as well as can be judged, shall give a dough of standard consistency. The dough may be mixed by hand in a basin, but the authors strongly recommend the use of one of Pfleiderer’s small doughing machines made specially for testing purposes : these have the great advantage that they mix the dough thoroughly, and with absolute uniformity. The machine is made with water-tight bearings, and is fitted with a revolution indicator by which the number of turns given to the handle are registered. Place the flour and water direct in the machine, and turn the handle so that the upper edges of the blades approach each 704 THE TECHNOLOGY OF BREAD-MAKING. other. When the flour and water are roughly mixed, scrape down the sides of the machine by means of a small spatula : note the position of the revolution indicator, and give the dough fifty revolutions. When suffi- ciently mixed, take the dough from the machine and set it aside in a small glass tumbler, or other vessel, for one hour. Cover over with a glass plate in order to prevent evaporation. When examining a number of samples, dough them up one after the other for an hour, and then come back to the further testing of the first one, and take them in rotation. Having thoroughly cleaned the cylinder and piston of the viscometer, fill the cylinder with the dough to be tested ; to do this, slightly open the bottom aperture and push in the dough through the top, by means of a stout spatula. In this way fill the cylinder completely, taking care that there are no air spaces ; shut the aperture, t, and then, holding the cylinder horizontally in the left hand, put on the cylinder cover, the piston being at the top of its stroke. Secure it by means of the bayonet catches, and stand the cylinder squarely on the base, a h. Arrange a vessel, w x, to receive the dough as forced through the instrument. Next have ready a watch with seconds’ hand (a chronograph is the most convenient thing, if one happens to be in possession of the worker) ; pull out the milled head, v, the piston begins to descend. As soon as the line r coincides with the top of k I, note the time, or start the chronograph : note again when the hne p descends to k I, and observe how long the piston has taken to travel this distance. If exactly sixty seconds, or whatever other standard has been selected, the dough is of the standard consistency, and the quantity of water used is that required by the particular flour to make a dough of the standard stiffness. Feel the dough with the fingers and see, especially, whether it seems hard or soft. A soft dough, which nevertheless goes through the machine slowly, must possess great tenacity. Such flours have almost invariably high water-retaining power. The test having been made, turn back the bayonet catches, and withdraw the cylinder cover, piston, and guide from the cylinder. Remove the dough from the piston, and clean out the cyhnder by means of a spatula. In handling the piston be careful not to hold it with the cover end uppermost, as the piston rod then slides backwards, and is stopped by the piston coming violently in contact with the cover. The piston being thin is liable by rough usage in this way to be forced off the rod. When the instrument is done with, the cylinder should be soaked in water, so as to remove any traces of dough that might clog the valve at the bottom. Having described the mode of using the instrument, its action on the dough may now be examined. In the first place, the lower edge of the piston and the upper one of the aperture through the cylinder bottom are both rounded, therefore the dough is not subjected to any cutting action. In the next place, the piston during its descent meets with no resistance wliatever except that due to the dough itself ; as it passes down through the hole in the cylinder cover it is impossible for the dough to find its way up through that opening against the downward movement of the piston ; consequently, there is no clogging whatever of the moving parts of the apparatus. The dough, in order to make its way out, has to alter its shape so as to pass through the small hole at the bottom, consequently its rigidity is here taken into account. At the end of the stroke, the piston is found to have pushed out a plug of dough from the centre of the cylinder, leaving a ring of dough standing round its outside. To force out this plug, the piston must liave torn away these particles of dough from the annulus (ring) of dough left standing. Hence it is that this apparatus registers so thoroughly the tenacity of the dough as well as its rigidity. By shading the dough in tlie figure an attempt has been made to indicate the probable lines of move- COMMERCIAL TESTING OF WHEATS AND FLOURS. 705 merit of the dough as the piston passes downwards. An inspection of the drawing of the viscometer, and a study of its principles, show that it is the condition of the dough, and that only, which can possibly affect the speed at which the piston descends. In practice it is well to have at least two tests made on the same flour with the viscometer. When the approximate water-absorbing power is knovTi, these may well be taken at 2 quarts below and 2 quarts above this point respectively. Having obtained a pair of piston readings, one above and the other below the sixty seconds (or other predetermined) standard, the actual quantity of water corresponding to the standard may be calcu- lated in the following manner For entering the tests it is recommended that a book be procured ruled both ways of the pe.ge : the water-absorption results should then be entered as showTi in Fig. 105, pa,ge 708. Supposing 70 quarts to have run through in 90 seconds, and 72 quarts in 50 seconds, then on drawing a line connecting these two points, the place where it crosses the horizontal line marked 60 in seconds, will give the wa.ter absorption in quarts. Thus referring to Flour No. 2, Fig. 105, the 72 quart dough ran through in 86 seconds, and the 74 quart dough in 43 seconds : on these l^oints being joined by a line, it cut the 60 seconds line at very nearly mid- way between the 72 and the 74 quart lines, therefore the water-absorbing capacity was taken as being 73 quarts. In this way, the absorptive power of various flours for intermediate points between two readings was arrived at. An inspection of Fig. 105 shows that the upper portions of these lines, graphically representing absorbing capacity, are very nearly parallel to each other. The authors find if the first test made gives a viscometer reading between 45 and 90, that the water absorption may be deduced vith sufficient correctness for most purposes in the following manner : — On a page, properly ruled both ways, set out two or three lines similar to those in Fig. 105 representing the water-absorbing power of different flours. Then, supposing a flour under examination has run through the viscometer in 87 seconds, with 68 quarts of water, make a mark at that point, and draw from it a line across the 60 seconds line, and pa^rallel to the lines of other flours previously set out. Reckon the water absorption from the point where it cuts the 60 seconds line. Such a flour would probably absorb about 69-5 quarts of water. Judging from a number of flours that have been tested in this manner, the single test gives results that very seldom are more than 0-5 quart off from those obtained by doughing the flour with two different quantities of water. Examples of a few detailed viscometer tests are given in the table on page 706. The heavier figures are the calculated quarts per sack for 60 seconds. 795. Stability Tests. — As the name implies, these are tests made in order to determine the rate at which a softening down of the flour occurs during the time it remains in the dough. An old-fashioned millers’ method of testing flours consisted in doughing them, allowing them to stand for some twenty-four hours, and then examining the stiffness of the dough. Sound flours would stand fairly well, while those which were unsound yielded doughs which “ ran to water.” The stability tests, made by the author with the viscometer, were simply modifications of these. Samples of doughs were kept for different periods of time in tumblers with glass covers, which fitted air-tight in order to prevent evaporation ; at the end of which time they were tested with the viscometer. The results of a number of such tests are given in the table on page 707, and are also represented in Fig. 105. The stiffness of dough is, as before remarked, affected to a very marked degree by its temperature, and this particularly applies to any tests allowed 706 THE TECHNOLOGY OF BREAD-MAKING. Results of Viscometer Tests on Flours. No. Names and Description of Flours. 1. Patent Flour, from American Hard Fyfe Wheat. 2. Bakers’ Flour ,, „ ,, 3. Hungarian Flour, First Patent. 4. English Wheat Flour. TIME ALLOWED TO REMAIN IN DOUGH— ONE HOUR. No. Quarts per i Sack. 1 Seconds. No. Quarts per Sack. Seconds. 1 66 215 66 223 1 i 68 193 68 200 1 70 74 70 107 71 60 72 86 1 52 73 60 ' 74 ’ 44 74 43 76 24 76 29 78 i 10 78 16 i 1 1 - I 80 12 74 255 58 183 76 170 60 120 1 78 60 62 82 3 80 38 4 63 60 82 25 64 27 84 18 66 19 86 10 — to stand for a length of time : it is well therefore in such tests to employ means of keeping the doughs at a uniform temperature during the whole time of standing. 796. Effect of Temperature. — In order to measure the effect of variations of temperature on water-absorbing power, the following tests w'ere made : — Water w^as taken at 32°, 40°, etc., F., up to 110° F. In order to keep them at the desired temperature, the doughs were placed in small glasses covered with air-tight plates, and these immersed in a vessel containing w^ater at the same temperature, in which they were kept for an hour. Three tests w^ere made with each flour at each temperature, and from these the dough of the standard consistency w as deduced in the manner previously described. The results of the tests are given on page 708. COMMERCIAL TESTING OF WHEATS AND FLOURS. 707 Water-absorbing Power of Flours after Standing Different Lengths of Time in the Dough. NOv Names and Description of Flours. 5. Straight Grade, from No. 2 Calcutta Wlieat. 6. ,, ,, ,, Saxonska Wheat. 7. Town Households, No. I. 8. Town Households, No. 2. TIME ALLOWED TO REMAIN IN DOUGH. No. IMMEDIATE. HALF-HOUR. THREE HOURS. TWENTY-FOUR ! HOURS ] Quarts per Sack. Seconds. Quarts per Sack. Seconds. Quarts per Sack. Seconds. Quarts per Sack. Seconds. 70 114 70 93 68 92 62 77 72 60 71 5 60 1 70 ! 60 64-5 60 5 72 53 72 50 70 ‘ 56 66 49 — — 74 29 72 40 68 30 — — — — 74 j 24 72 16 68 90 62 ! 104 60 19 ! 70 66 — — 65-5 60 62 11 6 70-5 60 — — 66 48 64 7 72 45 — — 68 33 66 1 5 — — — — 70 14 — — ! : j i 68 116 64 120 56 1 .1 125 70 76 — — 66 60 58 63 7 72 63 — - — 66 53 59 60 72 60 — — 68 47 60 ! 55 1 74 38 — — — — 62 I 40 64 160 64 132 62 64 55 60 i 66 76 65*5 60 62 i 60 56 35 8 ! 66-5 60 66 47 64 37 58 21 — — 68 25 1 66 30 60 18 — — — — — — 62 11 1 1 ! 64 8 Water-absorbing Power of Flours at Different Dough Temperatures. No. Names and Description of Flours. 1. A High-Class Brand of Hungarian Patent Flour. 2. A Patent Flour from Duluth Wheat. 3. A High-Class Patent Flour from all English Wheat. 708 THE TECHNOLOGY OF BREAD-MAKING. Quarts p3r Sack. Temperature. No. 1. No. 2. No. 3. 32° F. 84-5 720 640 40° „ 81*5 72-5 640 50° „ 77*5 700 610 60° „ 76-5 69-0 60-5 70° „ 70-5 66-0 550 80° „ 69-0 62-5 540 90° „ 670 61 0 520 100° „ 66-5 58-5 47-5 110° „ 610 56-5 44-5 From this table it will be seen that in every case there is a falling water-absorbing power wdth the increase of temperature. In the diagram below, Fig. 105, the results of the water-absorption tests on the table of flours, page 706, headed “ Results of Viscometer Tests on Flours,’^ have been drawn as a series of curves. On the horizonted lines (co-ordinates) are set oflthe number of seconds of time taken in each visco- meter test, while the numbers representing the quarts of water taken are given on the vertical lines (abscissae). The higher the water- a,bsorptive capacity, the further to the right does the curve of the flour appear ; and the more the rigidity of the dough is lessened by an equal increment of water, the more nearly vertical is the line of the curve. The results of tests on the loss of rigidity of dough of No. 8 Flour, a.s a consequence of standing, are also given on in this figure. They are marked S, a, h, c, d ; S a being the “ immediate ’’ test, and 8 d that after twenty-four hours. The softening down, as the result of standing, is well illustrated in the diagram. Fig. 105. — Diagram of Water- Absorption Results. Fig. 106. — Diagram of Variations OF Temperature Results. Fig. 106 above gives a graphic representation of the efle^ of varia- tions in temperature, as expressed above on this page. The quarts COMMERCIAL TESTING OE WHEATS AND FLOURS. 709 per sack are given on the horizontal lines, and the various temperatures on the abscissae. The greater the falling off in water-absorbing power with increase of temperature, or, in other words, the greater the softening of the dough, the more rapid is the descent of the curve. 797. Colour. — This is probably at the same time one of the most diffi- cult and most important tests to be made on flour. The great difficulty is that the colour of the flour itself is not necessarily a criterion of that of the bread produced. For example, some lower grade winter wheat flours look very white and even better coloured than harder spring wheat flours, whereas the bread made therefrom is exceedingly dark and ill-coloured. Further, the colour of the bread is dependent not only on that of the flour, but on the mode of working, and other factors which vary in themselves. Unless tests are made for no other purpose than the comparison of flours placed side by side, it is absolutely necessary to have some means of measuring and registering colour. The most familiar, and on the whole the most successful, instrument for this purpose is that known as Lovi- bond’s Tintometer or colour-measurer. As this appliance has been exten- sively employed in the following investigations, a description of it at this stage is necessary. 798. Lovibond’s Tintometer. — The instrument itself is an optical device. Fig. 107, by means of which a sample of flour, bread, or other body may be viewed side by side with a prepared surface of the purest white obtain- able. With the instrument is furnished a set of transparent standard tinted glasses. These are numbered from 0-01 upwards to 5-0, or higher if wished, so that any degree of depth of tint may be built up from these glasses, proceeding upwards by intervals of 0-01 at a time. For flour- testing purposes three series of such tinted glasses are employed. One of these is a Yellow, the second a Red, and a third Blue. The base. A, carries a stand, A^, which is supported in an oblique position by the strut, A^. On this stand is placed the opti- Fig. 107. — Lovibond’s Tintometer. cal instrument itself, B. This consists of a tube, blackened on the inside, and having apertures on the upper end, G, through which one looks in using the instrument. These openings are three in number, the outer ones being intended for use with both the eyes simultaneously, while that in the middle is for the purpose of one-eye examination. At the lower end of the tube, H, provision is made for the reception of two small cells, fitted with slits into which the standard glasses, J, are to be inserted. At F the coloured slabs under examination are placed for purposes of measurement. The spongy texture of bread gives it a mottled appearance when viewed through this instrument, and so a special device is necessary by which the sponginess may be transformed into an even and uniform tint. This is shown in Fig. 108, which is a plan of the tintometer arranged for this purpose. K M is a flat stand, on which the tintometer, B, is fixed. At L L, between the cells for standard glasses, and H, are placed two lenses such as those employed for spectacles. At W the standard white comparing surface is arranged, 710 THE TECHNOLOGY OF BREAD-MAKING. and the slice of bread under examination is fixed at Y. On looking through the eye-pieces at G, the lenses throw both the white surface, W, and the bread, Y, out of focus, so that they appear as even coloured, structureless surfaces. Fig. 108. — Tintometeb Fitted for Use with Bread. To use the tintometer, the standard white comparing surface must first be prepared. Fill one of the little trays supplied with the instrument with some speciedly prepared plaster of Paris, also supplied : press down with a piece of clean glass until a smooth uniform surface is obtained : if for bread, fill the cavity in the stand at W in the same way. When using the first arrangement of the instrument, stand it in a con- venient position facing a window looking toward the north, and, if possible, so that the light is from a white, cloudy sky, rather than when the sky is perfectly blue. In this latter case it is well to place a piece of white paper or white opal glass between the light and the surfaces being examined. On the one side of the field, F, place the tray of white, and the flour on the other. On looking down through the tintometer the flour will look much the darker. In the cell over the white surface put in some of the standard colour glasses already referred to — say, for example, 1-0 Y. (yellow) and 0*50 R. (red). The white light from the prepared surface passes up to the eye through these, and gives that surface an apparent yellowish red tint. Note whether the tint as a whole is lighter or darker than the flour, also whether too red or too yellow. If too dark and too red, remove the red glass and substitute a lighter one, and again compare. If too light and too red, add a little more yellow, leaving the red undisturbed. Very quickly it is possible to get the tint matched approximately : it is in getting an exact match that the difficulty occurs. It is well to try one or tw^o modifica- tions of the standard glasses, and see which comes the nearest. If the eye is uncertain, it is often an assistance to place a dark glass, say 5-0 Y., in front of the eye-piece, and look through the middle aperture at both the flours ; they appear much darker, but minute shades of colour are thus more readily distinguished. Having got the tint which so closely as possible matches the flour, a register should b^e made of the numbers of the glasses composing it. The bread form of the instrument should be arranged horizontally on a stand, so that it is at a comfortable height for the eyes of the observer when sitting, and so that the light comes from a window, over the shoulder, as shown by the arrow, P, Fig. 108. (If necessary, the instrument may of course be arranged for the light to fall from the right instead of the left.) Care must be taken that neither the surface, W, nor that of the bread has tlie shadow cast on it of any part of the apparatus. The use of the standard glasses in measuring is the same as before. It is scarcely necessary to say that colour judgments are difficult, and to point out that different persons’ eyes appreciate colours differently. One difficulty with the tintometer is, the comparison is being made between an opaque coloured surface in the case of the flour, and a tint imparted to a beam of light in the case of the test-surface — there is a difference in quality which makes comparison difficult. A desideratum is some form of permanent, graduated, tinted surface which can be compared with the flour. COMMERCIAL TESTING OF WHEATS AND FLOURS. 711 The great value of the tintometer is for from time to time permanently measuring and checking the colour of standard flour samples : this is well worth any trouble taken in so doing. The standards being thus kept veri- fied, it will be sufficient for ordinary purposes to check and compare flours side by side with the standards. 799. Colour Investigations. — In obtaining the readings made in con- nection with the following research, the judgment of four persons was, in many instances, utilised, while every reading was checked by at least two persons, and always, where the slightest doubt was felt, by three. Among methods of judging the colour of flour the most obvious is that of testing the flour itself in the normal dry condition. To this there is the objection that the colour of dry flour depends not merely on the nature of the wheat and the flour constituents, but also on the comparative coarse- ness or fineness of the particles of the flour. Further, on exposure to air flour very quickly bleaches, although this of course does not affect the validity of a test made on a sample taken from bulk. The bleaching of flour is commonly ascribed to light, but this is not essential, for in the follow- ing experiment the samples were kept during the intervcA between readings in a dark cupboard. The following three dry samples gave tintometer readings as under, being simply pressed into smooth slabs and examined : — Immediate. Yellow. Red. After standing one Day. Yellow. Red. American Spring Bakers . . 0-27 Ditto, another sample . . 0*34 American Winter Bakers . . 0-20 0*06 0-25 004 on 0-30 009 002 on 002 Pekar^s Test . — A second and well-known method of testing colour is to dip the compressed slabs into water, so as to wet the surface, then allow the same to dry off, and read or compare the colours. The tint is in this instance darkened considerably as a result of the action of oxydase in the presence of air, coloured oxidative products being formed. In this case, again, the degree of granulation of the flour affects the depth of colour — a coarse flour absorbs more water, and becomes darker through taking longer to dry, while the surface has more or less “ grain as a result of rough- ness of the surface before wetting. A third method consists of making the flour into dough, working it until perfectly smooth, and then examining and comparing. One objection to this method is that the colour of the dough darkens rapidly on the out- side, and hence, if an attempt be made to read off the colour, or even com- pare a series of three or more at a time, a new dough surface darkens visibly while the comparison is being made. To obviate this, the pellet of dough may be placed on a sheet of colourless glass, and the colour of the dough observed through the glass — in this way the colour of the dough proper is seen as distinct from that of the outer skin. It is no uncommon occurrence to take two flours from the same variety of wheat, the one very fine and the other granular, and compare them either dry or wetted in compressed slabs. The granular flour under both tests looks the darker , but on working them into dough, as just described, the coarser flour often produces the more “ bloomy "" dough ; bakers will at once form their own judgment as to which of the two will under similar conditions make the best loaf. Also, of course, the outer skin of the same samples may be compared and read if necessary. Investigation shows that the colour of dough is influenced by its degree of stiffness. Thus, a spring bakers’ flour was made into dough with different quantities of water, and the following readings taken at the expiration of one hour. At the end of eighteen hours, in which the doughs were kept 712 THE TECHNOLOGY OF BREAD-MAKING. in a water-saturated atmosphere, the colour of the outer skins was also read Colour of Dough. Colour of Skin. Yellow. Reel. Blue. Yellow. Red. Blue. 1. Doughed with 50 per cent, of water 1-50 0-68 0-08 3-55 2T0 0*86 2. Doughed with 55 per cent, of water 1*42 0-63 — 3-75 2T0 0-56 3. Doughed with 60 per cent, of water M9 0-54 — 3-15 1-90 0-48 The colour both of dough and skin is darker in the tighter doughs ; also this relation of colour holds good for some time, for at the end of eighteen hours the order of colour of the dough was the same as at the end of one hour. In order to eliminate so far as possible the differences due to variations in tightness of doughs, the whole of the Hours were in the subsequent tests treated with the quantity of water sufficient to make doughs of uniform stifiness. For this purpose each flour was tested by the viscometer in the manner previously described. The next step was to investigate the influence of the length of time the dough had stood on the depth of colour ; this, be it remembered, always being read through colourless glass. The following results were obtained : — Winter Winter Spring Spring American American American American Time. Patent. Bakers. Patent. Bakers. Y. R. Y. R. Y. R. Y. R. 1 hour after mixing 0-92 0-29 F37 0-94 102 0-64 1-34 110 2 hours after mixing 102 0*36 1-49 0*97 109 0-64 1-49 100 3 hours after mixing 108 0*40 L50 100 1-25 0-75 1-52 107 4 hours after mixing 1 TO 0-43 1-51 TOO 1-20 0-65 1-47 0-97 22 hours after mixing 108 0-58 1-50 102 1-20 0-75 1-46 107 It may be well here to explain the precautions taken in order to get as exact readings as possible. First of all, every series of tests to be read were arranged in order of colour as apparent to the eye ; then they were read in succession, commencing with the lightest. After matching No. I, No. 2 was placed against its (No. I’s) standard tint glasses and seen to be darker, then measured. In all cases where there was any apparent discrep- ancy the reading received a checking by three persons. When making time measurements the following method was adopted : — First of all, at the expiration of the time, the colour glasses of the preceding reading were again placed in the instrument, thus taking, for example, the two hours’ reading on the first flour just given, the one hour glasses, Y. 0-92 ; R. 0-29 were inserted, and the dough compared with them. It was thus definitely ascertained that a distinct darkening had occurred ; its measurement then followed. Each reading was thus compared with that preceding throughout the whole series. It will be observed that a slight but steady darkening occurs throughout the whole series, the increasing red or foxy tint “ sadden- ing ” the bloom of the yellow. Unless otherwise stated, future readings were made on doughs after standing one hour. The authors have also adopted another method of preparing the flour for examination, which is really a modification of the Pekarised slab method. The testing Pfleiderer doughing machine is thoroughly cleaned by making a stiff dough in it, and thus removing anything that would injure the colour. A dough is made by taking 30 grams of flour and 15 grams of water, and then pinning it out into a tliin sheet — say three-sixteenths of an inch thick — on a piece of glass. This is allowed to dry off in a dark place and then read just like the Pekar slab. It has the advantage of giving a smooth surface with all errors due to tlie “ grain ” of the flour eliminated ; but has the disadvantage that tlie degree of darkening depends somewhat on the thickness of the slieet. COMMERCIAL TESTING OF WHEATS AND FLOURS. 713 The next and final test is that made by baking the loaf and then observing the colour of the bread. It is scarcely necessary to point out to bakers that colour is influenced by the kind of yeast used and mode of working ; but using the same yeast, it was thought well to register the effect produced by the mode of fermenting employed, and especially the time of fermentation. A spring American bakers’ flour was first made into an off-hand dough in the following manner : — 10 lbs. flour, 5 lbs. water at 90° F., IJ oz. compressed yeast (Delft Pure), and IJ oz. salt, were taken and made into dough at 5 p.m. The dough was then maintained at a temperature of 80-82° F. during the whole time of the experiment. At intervals a 2 lb. piece was taken, moulded, and baked. On the next morning the loaves were cut, the colour examined, and also the total acidity, reckoned as lactic acid, determined. On the second day also the colour was read, a freshly-cut surface being used for that purpose. The following table gives the results obtained. The first column gives the number of hours after setting the dough until the loaf was placed in the oven ; the first day’s colour readings follow in the second column, the next day’s in the third, and the acidities in the last : — Tests Bakers’ Flour — Off-hand Dough. No. Houra. First Day’s Colour. Y. R. B. Second Day’s Colour. Y. R. B. Acidity per cent. 1 4 211 L41 0-30 1-85 L25 0-16 0-57 2 6 L75 L25 018 1-91 MO 0-26 0-63 3 8 L75 100 010 1-85 MO 0-26 0-66 4 10 L75 L20 0-10 L75 L30 0-26 0-69 5 12 1-70 M5 005 1-66 L20 0-24 0-73 6 131 1-70 L20 0-30 L75 1-40 0-30 0-79 Fermentation had not proceeded sufficiently far to properly raise the first loaf, which was somewhat close and heavy, and also dark in colour ; but it should be borne in mind its texture could scarcely be in fairness com- pared with that of the other numbers of the series. The last showed signs, but only slight, of darkening — due doubtless to the commencement of those changes which accompany sourness. The loaves Nos. 2 to 5 do not vary greatly in colour, but there is a slight diminution of the depth of tint. Taken as a whole, this series darkened before the second day. In another series of tests two doughs were worked with a flour ferment. The one was from a spring American patent flour ; the second from a bakers’ grade from the same wheat. The following quantities were in each case employed : — J lb. flour 3 oz. compressed yeast > Ferment. 5 lbs. (2 quarts) water at 102° F.j 9i lbs. flour Dough. The ferment was allowed to work 45 minutes from the time of being set ; then the dough was made, and one loaf immediately taken. This was allowed to prove, and at once baked. Loaves were taken at intervals as shown in the following table, in which is also given the colour and acidity both on the first and second day after baking. It should be added that the first loaf was baked at about 9.15 p.m. 714 THE TECHNOLOGY OF BREAD-MAKING. Tests on Bakers’ Flour — Flour Ferment and Dough. {Same sample as used in previous series.) No. Hours. First Day’s Colour. Y. R. B. Acidity per cent. Second Day’s Y. R. Colour. B. Acidity per cent. 1 Immediate 1-80 115 0-50 0-65 1-40 0-96 006 0-59 2 2 hours 1*65 1*20 0-40 0-73 1-48 100 004 0-71 3 4 „ 1-65 1-30 0-40 0-72 1-42 100 004 0-90 4 6 L90 1-80 0-60 105 1-60 1-40 005 M2 5 71 * 2 5’ 2-20 2-08 0-75 M7 1-60 1-45 0-08 1-27 6 94 „ 2-22 215 0-75 MO 1-65 1-40 0-08 1-34 Remarks. No. 1. Very close and heavy. No. 2. Sweet, good loaf. No. 3. Colour slightly worse, odour faulty. No. 4. Decidedly sour, rapid darkening in colour commenced. No. 5. These changes intensified. No. 6. These changes still more marked. The colour here distinctly fell off, with increase of acidity, a distinct difference being observed even between Nos. 2 and 3. The off-hand doughs were, as a series, whiter than those prepared with a ferment, but this is probably due to the excessive fermentation in the latter series, which was intentionally pushed to an extreme. Taken as a whole these loaves were distinctly less coloured on the second day. The foUovdng are the results of the corresponding series of tests on patent flour : — Tests on Patent Flour. No. Hours. First Day’s Colour. Y. R. B. Acidity per cent. Second Day’s Colour. Y. R. B. Acidity per cent. 1 Immediate 1-45 0-70 — 0-29 1-40 0-72 — 0-32 2 2 hours 1*40 0-62 — 0-35 1-60 0-73 005 0-37 3 4 „ 1-30 0-60 — 0-50 L32 0-65 006 0-52 4 6 „ 1-75 0-98 — 0-63 1-60 101 — 0-68 5 71 '2 1-70 101 — 0-70 1-40 0-90 — 0-73 6 9| ,, 1-70 102 — 0-75 1-48 0-93 — 0*82 Remarks. No. First Day. Second Day. 1. Close and heavy — Sweet Sweet. 2. Bright and good bloom — Sweet Sweet. 3. Greyer, very little different — Sweet, and 3 good volume . . Both 2] j . . , 1 Incipient sourness. 4. Smaller, darker, slightly sour . . . . Sour. 5. Smaller, darker, sourer . . . . Sour. 6. Very small, dark, very sour . . Very sour. Again, with an increase of acidity, there is also a darkening of colour ; and in the earlier numbers of the series also a darkening on the second day’s reading as compared with the first. There is a property of bread colour to which attention has already been drawn by Abercromby, which property renders comparison difficult both to the eye and also the tintometer. That property is “ a silky texture in the bread, which, by reflecting the light, gives an appearance of better colour.” To this characteristic the author ventures to apply and appropriate the term “ sheen.” The difficulty is that a loaf looks more “ sheeny ” in one position than another ; not only may Tests by Various Methods on the Colour of Flour. COMMERCIAL TESTING OF WHEATS AND FLOURS. 715 CO 0 C G 0 c3 c3 .G g: GO -^s 4S • F^ o ^ ^ o -(S cc ^ ^ EG o "o IB >j la s ,.6 6.6 fh il a a o o : O 3c -G O G! O 05 o ^ 1 s S S (N ^ lo 7ti CO »o o O 05 r- F+H Ti< rH o c• (M X X G<1 i c • 05 00 O O (M O lO - 73 .S' is oi O ‘cc i i—H o “ c CO ^ C>-r 1 5 2 CO 4 7 6 8 05 TtH 3 6 2 1 5 7 X 05 o "o o C ^ .SP ; <01 01 CO CO lO CO X ^ o o o o 6 6 6 6 6 6 666666 6 6 6 "o 1 ^ . 7^ 1 2 3 5 6 7 8 05 - 2 3 4 5 6 7 X 05 o ' c Is ' e -6 ^ ci iisrJci c i. FP«i i si o 6 cjF ^ Cc F-i II 02 02 |o 02 02 02 716 THE TECHNOLOGY OF BREAD-MAKING. two observers, tlie one looking over the other’s shoulder, get a different im- pression, but the sheen may be affected even by slightly turning or altering the position of the loaf. One reason why the patent flour breads suffer in colour on the second day is the loss of brilliance or sheen. The table on page 715 gives the results of examining a number of flours for colour by the various methods described. In every case the order of the substances as they appeared to sight is given, as well as the reading by the tintometer ; between these there are but few discrepancies, and these mostly occur in the case of bread, where the disturbing influence of irregular surface and scattered reflection of light acts most powerfully. But even in these the divergence is not great. The tintometer reading is probably the truer register of absolute colour, the dis- turbing effect of side reflections, etc., being practically entirely counter- acted. But the public does not view bread through a tintometer as a pre- liminary to purchase, and hence a doubt arises as to which is the most trustworthy baker’s reading, that, or the general effect on the eye. A point of more importance is the relationship existing between the various modes of judging colour of flour, and the colour of the resulting bread. In the series of results just tabulated, the colour of the dry flour agrees most closely with that of the baked loaves ; while, contrary to expectation, there is considerable discrepancy between the colour of the dough and that of the bread. It should be noted that if the flours (which were all American) be divided into the two classes of spring and winter, many of the differences disappear. Although a good many results are here accumulated, they do not afford sufficient data on which to generalise, but they do show the extent of agreement and disagreement between various methods of testing flour for colour in common employment. 800. Effect of Age on Flours. — The experiments set forth in the table on page 717 were made in order to determine the effect of age on American flours. All the tests were made at various times on 14-lb. samples, stocked meantime in close textured canvas bags. The flrst tests were made on the arrival of the flours in this country in October ; the second series after the lapse of three months, in January ; and the third after the expiration of another two months, in March. The colour on dry flour, wet gluten, and water absorption by viscometer were in each case determined. With increase of age a slight, but only a slight, amount of bleaching is observed. In connexion with this, it will be of interest to note the dif- ference in colour between a sample of flour by which purchase was made on Mark Lane, and the colour of bulk when delivered some weeks later. The seller alleged that the difference in colour between bulk sample and selling sample was due to bleaching of the latter in the interval between date of purchase and arrival of the flour Colour of Sample. Dry Flour . . . . 010 Y. -f 0 01 R. Pekarised Flour . . 1’32 Y. -f- 0*50 R. Dough, through glass . . 1-10 Y. + 0-60 R. Bulk. 0-32 Y. -f 0 09R. 2-20 Y. -f 0-90 R. L50 Y. -f-0-90R. Comparing the above results with the amount of bleaching on authentic samples, comment is unnecessary. Tlie amount of gluten and also water-absorbing power by viscometer show generally signs of slight diminution. 801. Changes undergone by Flour Samples during Storage, Jago and Ellis. With the view of obtaining definite information as to the changes which flour samples undergo during keeping, the following investigation COMMERCIAL TESTING OF WHEATS AND FLOURS. 717 No. 1. Effect of Age on Flours. Bakers’ Flour from Duluth Wheat. „ 2. Patent „ 3. Bakers’ ,, Manitoban Wheat. „ 4. Patent „ 5. Bakers’ ,, Indiana Winter Wheat. „ 6 . Patent 55 55 „ 7. Bakers’ ,, Ohio Winter Wheat. „ 8. Patent 55 55 55 1. 2 . 3 . 4. 5 . 6. 7 . 1 Colour. New .. .. 0-30 0-21 0-27 1 0-22 0-20 1 0-07 0-18 0-06 0-07 0 04 0-06 : 0-06 0-03 j 0-02 003 0-02 Three months old 0-29 0-07 0-22 0-02 0-27 0-06 , 0-22 1 0-04 0-16 0-03 1 0-06 0-02 0-16 0-02 0.08 0-01 Five months old -j ^ 0-28 0-07 0-21 002 0-26 0-04 1 0-22 0-04 0-16 ; 0-03 0-06 0-02 0-14 0-02 0-06 0-01 Wet Gluten. 1 Xew . . . . . . 44-0 42-0 44-5 39-0 37-0 f 28-9 33-7 31-8 Three months old 43-7 41-7 37-4 36-2 30-6 291 33-3 30-2 Five months old 43-2 41-2 35-7 35-0 30-1 28-9 32-7 30-3 Water Absorption. Xew 69-5 68-0 66-0 63-5 59-0 530 56-0 57-5 Three months old 68 -5 67-0 67-5 66-0 60 -0 i 55-0 56-0 55-5 Five months old 66-0 ’ 62-0 1 66-0 63-0 55-0 51-0 56-0 1 55-0 was made by one of the authors in conjunction with Mr. Ellis, a student in his laboratory, and a practical baker of long experience. In the month of February sample half-sacks of new flour were kindly furnished by a number of millers. The various flours received the following numbers, a short description of each being given : — 1. Top Grade Soft Coloury Flour. 2. Household Grade Soft Coloury Flour. 3. Top Grade Hungarian Flour. 4. Low Grade Hungarian Flour. 5. Top Grade Strong Flour. 6. Medium Grade Strong Flour. 7. Household Grade Strong Flour. 8. Top Grade Medium Strength Flour. 9. Medium Gra,de Medium Strength Flour. Each bag of flour was weighed off into 7 lb. sample bags, made of double thickness of fine cotton material. One-half the number was stored in a cold room subjected to the ordinary changes of climate in the matters of temperature and moisture. The remainder Avere stored in a flour loft over a. bakery, where the temperature ranged somewhat high. Beyond the protection afforded by the bags themselves, the flours were not screened from the action of light, but were not exposed to direct sunshine. In addition to the 7 lb. samples, a 1 lb. sample of each flour was placed in a double thickness bag, and this in turn stored in a tin canister, with tightly-fitting lid. On March 2 these arrangements were completed, and the flours Avere 718 THE TECHNOLOGY OF BREAD-MAKING. then systematically examined, and afterwards periodically tested on the dates given in subsequent tables. The following determinations were made on each flour : — Percentage of moisture. Percentage of wet and dry gluten. Water absorption by the viscometer. Colour on dry flour, and wetted and dried (Pekarised) flour, by tinto- meter and by comparison with standard slabs. Baking tests on 560 grams (approximately 20 ounces) of flour. The moisture was determined in the usual manner. The glutens were determined in duplicate, and checked by a fresh test in any cases of dis- crepancy. The water absorption is in each case the mean of several deter- minations, and the results as gained by the viscometer, checked by careful hand examination of the dough itself. The colour of flours, and also breads, was read as accurately as possible by the tintometer ; in each case the colour was checked by comparing it with a tint which was decidedly lighter, and also with one which was perceptibly darker, thus getting not only a reading which appeared to match the flour, but also one which was too dark and another which was too light. These readings were usually about OT lighter or darker than the matching tint. Thus in one case 0*75 yellow -f 0-60 red. — Too light. 0*90 yellow + 0-75 red. — Match. 0-95 yellow + 0*80 red. — Too dark. In the baking tests the weight of the dough, yield of bread, colour, general appearance, and working characteristics, are in each case noted. The yield of bread is that judged to result when cottage dough is made, and is calculated from the actual weight of fermented dough. It may be mentioned that in all small tests the apparent yield is greater than the same flour gives on the commercial scale. In the following tables are given the results of the various tests made on each flour. The viscometer results are given in quarts per sack. The moisture, wet, dry, and true, gluten are in percentages of the flour. The water used in dough-making is calculated to quarts per sack. The weight of fermented dough is calculated to lbs. per sack, and from this is calculated the number of quarterns per sack, dough being weighed off at 4 lbs. 6 oz. COMMERCIAL TESTING OF WHEATS AND FLOURS. 719 No. 1 Flour. Cold Storage. Visco- meter. Moisture. Wet Gluten. Dry Gluten. True Gluten. Water used in Doughing. Quarts per Sack. Weiglit of Fermented Dough. Lbs. Quarterns per Sack. Arrival. 57 15-33 38-5 13-2 51 420-0 96-6 2nd. week 58 14-75 35-7 12-2 10-7 54 425-0 97-7 4th. ,, 57 15-34 38-7 13-0 — 56 425-0 97-7 6th. ,, 55 15-30 38-0 13-1 — 57 430-0 98-9 10th. 52 15-5 35-9 12-2 — 52 410-0 94-3* 13th. „ 55 15-4 35-8 12-3 — 52 407-5 93-7 Hot ' Storage. Arrival . . 57 15-33 38-5 13-2 51 420-0 96-6 1st. week 69 12-91 37-0 12-9 — 53 417-5 95-9 3rd. „ 70 11-80 39-0 13-0 10-2 55 422-5 97-1 5th. 73 10-25 38-0 13-7 — 59 430-0 98-9 7th. „ 75 9-8 38-0 13-7 — 66 450-0 103-5 11th. „ 75 8-9 38-0 12-33 — 66 470-0 108-1 14th. „ 69 8-95 38-0 1 12-32 1 65 1 447-5 102-9 Colour by Tintometer. Cold Storage. Dry Flour. Pekarised. Crumb. Yellow. Red. Yellow. Red. Yellow. Red. Arrival 0-28 0-21 0-80 0-81 1-7 0-81 2nd. week . . 0-18 0-03 0-90 0-80 1-6 0-85 4th. ,, 0-12 0-06 0-50 0-40 1-4 0-74 6th. „ . . 0-14 0-05 0-80 0-50 1-3 0-71 10th. „ 0-20 0-19 0-30 0-55 1-2 0-84 13th. ,, 0-20 0-17 0-80 0-58 1-1 0-86 Hot Storage. Arrival 0-28 0-21 0-80 0-81 1-7 0-81 1st. week . . 0-22 0-12 0-73 0-80 1-4 0-81 3rd. „ 1 0-29 0-07 0-90 0-80 1-3 0-76 5th. „ 0-22 0-06 0-80 0-70 1-2 0-74 7th. „ 0-23 0-07 0-60 0-54 1-4 0-80 11th. „ 0-20 0-10 0-80 0-59 1-4 0-90 14th. „ 0-20 0-14 0-85 0-58 1-4 1-00 * This one gone musty. 720 THE TECHNOLOGY OF BREAD-MAKING. ■No. 2 Flour. Cold Storage. Visco- meter, Moisture. Wet Gluten. Dry Gluten. True Gluten. Water used in Doughing. Quarts per Sack. Weight of Fermented Dough. Lbs. 1 Quarterns j per Sack. Arrival . . 59 ' 14-73 43-7 14-3 ! _ 53 417-5 96-0 2nd. week 59 14-15 38-5 13-7 11-8 55 4240 9'7-5 ' 4th. „ 59 15-03 45-3 15-3 — 56 430 0 98-9 ! 6th. „ 59 15-10 45-0 15-4 — 56 427-5 98-3 1 10th. ,, 57 14-9 44-3 14-0 — 56 425 0 97-7 ' 13th. „ 57 1 13-95 1 47-8 14-5 1 50 415-0 95-4 ! Hoi ' Storage. i Arrival . . 59 14-73 43-7 14-3 53 417-5 96-0 1st. week 60 12-28 42-0 14-4 — 55 422-5 97-1 ^ 3rd. „ 64 11-45 43-0 15-4 12-6 58 4250 97-7 : 5th. ,, 67 10-20 43-2 14-7 — 60 432-5 99-4 7th. ,, 68 10-0 46-2 15-0 ■ — 60 4320 99-4 I 11th. „ 68 9-5 43-0 15-1 ■ — - 64 457-5 105-2 14th. „ 70 7-85 39-35 14-2 - — ■ 64 440 0 101-2 i Colour by Tintometer. Coll 1 Storage. Dry Flour. Pekarised. Crumb. Yellow. Red. Yellow. Red. Yellow. Red. 1 Arrival 0-30 0-22 0-80 0-83 1-4 i 0-82 1 2nd. week . . 0-22 0-10 0-80 0-60 1-5 0-88 i ! 4th. „ 0-11 0-08 0-80 0-62 1-6 0-91 ; 1 6th. „ . . 0-17 0-07 0-89 0-69 1-3 0-83 ' 10th. ,, 0-21 0-08 0-90 0-70 1-3 0-82 13th. „ 0-21 0-09 0-90 0-80 1-2 1-0 ! 1 [ Hot Storage. Arrival 0-30 0-22 ' 0-80 0-83 1-4 0-82 I 1st. week . . 0-22 0-18 ' 0-71 0-80 ! 1-4 0-82 1 3rd. „ 0-25 0-10 1 0-80 0-81 1-7 0-79 ! 5th. ,, 0-25 0-08 0-89 0-74 1-6 0-78 1 7th. ,, 0-26 , 0-08 0-80 0-59 1-5 0-92 1 11th. „ 0-22 0-12 j 0-93 0-65 1-5 0-98 ! 14th. „ 0-20 0-16 1 0-90 0-60 1-3 1-0 COMMERCIAL TESTING OF WHEATS AND FLOURS. 721 No. 3 Flouk. Cold Storage, Visco- meter. Moisture. Wet Gluten. Dry Gluten. True Gluten. Water used in Doughing. Quarts per Sack. Weight of Fermented Dough. Lbs. Quarterns per Sack. Arrival . . 63 12-81 34-8 12-3 1 61 4350 100-0 2nd. week 65 11-92 31-5 10-2 9-5 63 442-5 101-7 4th. „ 63 13-75 36-6 11-9 — 67 452-5 104-0 6th. ,, 63 14-40 35-0 11-9 — 67 452-5 104-0 lOth. „ 60 12-6 34-9 11-0 ■ — 60 431 0 99-1 13th. „ 63 13-2 35-0 10-75 ■ — 56 4250 97-7 Hot Storage. Arrival . . 63 12-81 34-8 12-3 61 435 100-0 1st. week 70 11-40 32-5 11-3 ■ — 65 446 102-5 3rd. ,, 71 11-30 32-0 10-5 9-0 65 447 106-9 5th. „ 72 9-16 36-0 12-1 ■ — 71 462 106-3 7th. „ 72 9-05 37-1 12-8 — 73 469 107-8 11th. ,, 73 8-9 36-2 11-6 — 73 469 107-8 14th. ,, 74 8-07 34-5 11-09 — 73 472 108-6 Colour by Tintometer. Cold Storage. Dry Flour. Pekarised. Crumb. Yellow. Red. Yellow. Red. Yellow. ! Red, Arrival 0-30 0-10 1-0 0-80 1-4 1-0 2nd. week 0-11 0-10 0-70 0-53 1-5 0-89 4th. ,, 0-10 0-06 0-70 0-50 1-6 0-90 6 th. „ 0-14 0-05 0-80 0-45 1-3 0-56 10th. „ 0-14 0-08 0-80 0-60 1-3 0-80 13th. „ 0-12 0-09 0-80 0-60 1-35 0-82 Hot Storage. Arrival 0-30 0-10 1-0 0-80 1-4 1-0 1st. week 0-20 0-11 0-80 0-63 1-4 0-90 3rd. ,, 0-20 0-04 0-88 0-50 1-5 0-72 5th. ,, 0-20 0-08 0-90 0-50 1-4 0-73 7th. „ 0-20 0-08 1-1 0-92 1-46 0-60 11th. „ 0-20 0-09 0-75 0-54 1-3 0-81 14th. ,, 0-20 0-09 0-80 0-56 1-3 0-81 722 THE TECHNOLOGY OF BREAD-MAKING. No. 4 Flour. Cold Storage. Visco- meter. Moisture. Wet Gluten. Dry Gluten. True Gluten. Water used in Doughing. Quarts per Sack. Weight of Fermented Dough. Lbs. Quarterns 1 per Sack. Arrival . . 72 12-65 30-3 11-6 70 460 i 105-8 2nd. week 74 12-56 32-2 11-0 10-6 70 460 105-8 4th. „ 73 14-77 35-4 11-9 — 72 462 106-2 ! 6th, 72 14-60 34-0 11-8 — 72 - 466 107-1 10th, 71 14-9 34-5 11-8 — 69 451 103-7 13th ., * Hot Storage. Arrival . . 72 12-65 30-3 11-6 700 460 0 105-8 3rd. week 75 10-0 34-0 11-7 — 720 471-5 108-4 5 th. , 78 11-0 33-0 11-9 11-1 720 471 0 108-2 7th. „ 80 9-15 34-9 12-6 . — 72-75 4660 107-1 nth. „ 81 8-9 35-0 12-9 — 730 4690 107-8 14th , 81 8-5 34-0 12-5 • — 770 4750 109.2 Colour by Tintometer. Cold Storage. Dry Flour. Pekarised. Crumb. Yellow. Red. Yellow. Red. Yellow. Red. Arrival 0-29 0-20 1-0 0-99 1-3 1-0 2nd. week . . ; 0-10 0-11 0-92 0-71 1-5 1-2 4th. ,, 0-10 0-07 0-90 0-76 1-4 0-90 6th. „ 0-14 0-08 1-0 0-84 1-4 0-60 lOtli. „ 0-24 0-23 1-0 0-70 1-4 0-80 13th. „ . . * — — — — ' Hot Storage. 1 Arrival 0-29 0-20 1-0 0-99 1-3 1-0 1st. week . . 1 0-25 0-20 1-0 0-80 1-3 1-0 3rd. „ ! 0-29 0-10 0-96 0-70 1-5 1-0 5th. „ 0-29 0-09 0-98 0-89 1-4 1-0 7th. „ 1 0-21 0-09 1-0 0-92 1-4 0-60 11th. „ 1 0-22 0-23 0-85 0-55 1-5 1-0 14th — Too musty and dark for baking purposes. COMMERCIAL TESTING OF WHEATS AND FLOURS. 723 No. 5 Flour. Cold Storage. Visco- meter. Moisture. Wet Gluten. Dry Gluten. True Gluten. Water used in Doughing. Quarts per Sack. Weight of Fermented Dough. Lbs. Quarterns per Sack. Arrival . . 68 1306 40-2 13-3 63 442-5 101-7 2nd. week 69 130 37-8 14-5 12-9 64 442-5 101-7 4th. „ 68 1410 46-2 14-8 ■ — 65 4470 102-8 6th. „ 67 13-65 46-0 14-8 — 65 4510 103-7 10th. ,, 63 13-9 45-0 13-35 — 61 4390 100-9 13th. „ 65 13-8 45-7 13-25 — 59 427-5 98.3 Hot Storage. Arrival . . 68 13-06 40-2 13-3 630 442-5 101-7 1st. week 68 11-70 41-0 14-0 — 650 448-5 103-6 3rd. „ 70 11-65 44-0 15-5 12-1 68-0 4550 104-6 5th. ,, 73 9-75 44-5 15-4 — 69-5 461 0 107-8 7th. „ 73 8-2 47-3 15-7 — 70-0 4560 104-8 11th. „ 75 8-0 44-5 14-7 — 710 4660 107-1 14th. „ 75 8-5 44-45 14-4 — 710 4650 107-0 Colour by Tintometer. Cold Storage. Dry Flour. Pekarised. Crumb. Yellow. Red. Yellow. Red. Yellow. ! Red. 1 Arrival 0-30 0-21 0-87 0-70 1 2-0 0-81 2nd. week . . 0-27 0-09 0-90 0-80 ! 1-3 0-80 4th. ,, 0-12 0-06 0-50 0-40 2-0 1-2 6th. ,, 0-14 0-06 0-99 0-75 1-4 0-73 10th. „ . . 0-20 0-81 1-0 0-80 1-4 0-88 13th. ,, 0-27 1-0 0-98 0-80 1-38 0-86 Hot Storage. Arrival 0-30 0-21 0-87 0-70 2-0 0-81 1st. week 0-29 0-12 1-3 0-91 1-5 0-88 3rd. „ 0-28 0-08 1-2 0-85 1-4 0-74 5th. ,, 0-21 0-10 1-1 0-70 1-2 0-70 7th. „ 0-20 0-09 1-04 0-56 1-4 0-59 nth. „ 0-23 0-10 0-91 0-68 1-4 0-85 14th. „ 0-20 0-10 0-93 0-64 1-3 0-85 724 THE TECHNOLOGY OF BREAD-MAKING. No. 6 Flour. Cold Storage. Visco- meter. Moisture. Wet Gluten. Dry Gluten. True Gluten. Water used in Doughing. Quarts per Sack. Weight of Dough Lbs. per Sack. Quarterns per Sack. Arrival . ; 70 12-67 42-3 13-5 64 441-5 101-5 2nd. week 70 13-2 40-5 14-5 12-5 64 4450 102-3 4th. „ 66 13-75 40-1 12-8 — 64 440 0 101-2 6th. ,, 67 14-28 41-0 12-9 — 64 4400 101-2 10th. „ 68 14-0 41-5 12-7 — 59 4330 . 99-5 13th. „ 65 13-5 42-5 12-8 — 61 437-5 100-6 Hot Storage. Arrival . . 70 12-67 42-3 13-5 64 441-5 101-5 1st. week 70 10-72 44-5 13-1 — 64 445.0 102-3 3rd. „ 71 13-21 43-0 15-0 12-0 68 4560 104-8 5th. ,, 74 10-26 43-0 14-0 — 69 4580 105-3 7th. „ 76 9-34 46-0 14-0 — 69 457-5 105-2 nth. „ 76 9-15 45-3 14-8 ■ — 74 4750 109-2 14th. „ 76 8-60 44-1 14-26 — 76 480-0 110-4 Colour by Tintometer. Cold Storage. ! Dry Flour. Pekarised. Crumb. Yellow. Red. Yellow. Red. 1 Yellow. Red. Arrival 0-30 • 0-22 0-92 0-70 1-7 0-81 2nd. week . . 0-30 0-06 0-90 0-81 1-4 0-90 4th. ,, 0-22 0-06 0-84 0-66 1-4 0-80 6th. „ . . 0-17 0-06 0-90 0-64 1-38 0-88 10th. „ . . 0-26 0-08 1-01 0-60 1-35 0-87 13th. 0-26 0-08 1 0-95 0-70 1-34 0-80 Hot Storage. Arrival 0-30 0-24 0-92 0-70 1-7 0-81 1st. week . . 0-30 0-14 1-2 0-99 1-4 0-76 .3rd. „ 0-34 0-10 1-2 0-90 1-4 0-76 5th. ,, 0-.30 0-10 1-1 0-70 1-3 0-71 7th. „ 0-22 0-09 1-1 0-70 1-5 0-59 nth. „ 0-22 0-09 0-94 0-88 1-42 0-80 14th. ,. 0-22 0-09 1 0-90 0-65 1-43 0-80 COMMERCIAL TESTING OP WHEATS AND PLOURS. 725 No. 7 Ploue. Cold Storage. Visco- meter. Moisture. Wet Gluten. Dry Gluten. True Gluten. Water used in Doughing. Quarts per Sack. Weight of Fermented Dough. Lbs. Quarterns per Sack. Arrival . . 69 12-61 45-1 14-6 67 446-5 102-6 2nd. week 69 13-05 44-0 15-0 13-4 67 469-5 104-0 4th. ,, 69 14-11 47-2 15-1. • — 65 4500 103-5 6th. ,, 70 14-56 47-0 15-1 — 63 442-5 101-7 loth.- „ 66 14-2 46-1 15-0 ■ — 63 442-5 101-7 l-3th. „ 68 13-82 45-0 14-8 — 64 4450 101-9 Hot Storage. Arrival . . 69 12-61 45-1 14-6 670 446-5 102-6 1st. week 69 10-72 43-0 14-6 • — 670 454-5 104-5 3rd. „ 70 13-21 43-8 14-7 14-0 710 465 0 106-9 5th. ,, 73 10-26 46-1 15-3 — 71-5 464 0 106-7 7th. „ 75 9-34 48-2 15-4 • — 720 465 0 106-9 11th. „ 75 9-0 47-3 15-0 — 710 460 0 105-8 14th. ,, 76 8-20 44- 1 15-75 — 74-0 472-5 108-6 Colour by Tintometer. Cold Storage. Dry Flour. P6karised. Crumb. Yellow. Red. Yellow. Red. Yellow. Red. Arrival 0-38 0-30 1-07 0-90 1-6 1-1 2nd. week . . 0-31 0-26 0-90 0-80 1-8 0-82 4th. ,, 0-30 0-20 1-0 0-80 1-6 0-91 6th. ,, 0-30 0-20 1-01 0-90 1-5 0-96 10 th. ,, 0-27 0-22 1-03 0-80 1-4 0-88 13th. „ 0-28 0-20 1-1 0-80 1*7 1-2 Hot Storage. Arrival 0-38 0-30 1-07 0-90 1-6 1-1 1st. week 0-31 0-20 1-3 1-0 1-8 1-1 3rd. „ 0-30 0-19 1-5 1-0 1-9 0-79 5th. ,, 0-30 0-19 1-2 0-70 1-4 0-75 7th. „ 0-28 0-10 1-0 0-76 1-5 0-60 11th. „ 0-21 0-12 1-0 0-70 1-53 0-80 14th. „ 0-27 0-10 1-0 0-76 1-5 0-90 726 THE TECHNOLOGY OF BREAD-MAKING. No. 8 Floue. Cold Storage. Visco- meter. Moisture. Wet Gluten. Dry Gluten. True Gluten. Water used in Doughing. Quarts per Sack. Weight of Dough. Lbs. per Sack. 1 1 Quarterns i per Sack. I 1 Arrival . . 62 1440 40-2 13-4 56 426-0 97-8 2nd. week 64 13-70 35-1 13-1 12-9 58 430-0 98-9 j 4th. „ 62 1408 40-3 14-2 — 58 437-5 100-6 ! 6th. ,, 63 13-56 40-0 14-5 — 60 435-0 100-5 ; 10th. ,, 59 14-0 39-5 14-0 — 69 435-0 100-5 1 13th. „ 61 14-0 37-4 13-2 — 56 425-0 97-7 ; Hoi ' Storage. i Arrival . . 62 14-40 40-2 13-4 56 426 97-8 1st. week 65 10-65 40-5 14-5 12-47 58 434 99-8 3rd. „ 68 11-65 39-0 13-3 — 57 *426 98-9 5th. ,, 71 9-10 40-0 14-7 — 58 449 103-3 7th. „ 72 9-1 40-0 14-5 — 66 451 103-7 nth. „ 73 9-05 40-2 14-1 — 69 469 107-8 ; 14th. ,, 73 7-25 41-0 13-85 — 69 455 104-6 COLOUE BY Tintometee. Cold Storage. ’ Dry Flour. Pekarised. Crumb. Yellow. Eed. Yellow. Eed. Yellow. Eed. ! Arrival 0-34 0-20 0-80 0-70 1-9 1-1 2nd. week . . 0-20 0-11 0-71 0-60 1-6 0-90 ; 4 th. 0-18 0-08 0-60 0-53 1-4 0-71 6 th. ,, 0-20 0-09 0-84 0-51 1-5 0-60 i 10 th. 0-28 0-10 0-84 0-70 1-4 0-85 S 13th. 0-21 0-10 0-80 0-69 1-2 0-80 i Hot Storage. i Arrival 0-34 0-20 0-80 0-70 1-9 1-1 : 1st. week 0-30 0-17 1-5 0-99 1-6 0-89 3rd. ,, 0-20 0-12 1-3 0-90 1-3 0-80 • 5 th. ,, 0-21 0-11 0-90 0-72 1-3 0-77 7th. ,, 0-28 0-10 0-74 0-50 1-4 0-68 11th. „ 0-21 0-11 0-70 0-55 1-4 0-67 ' 14th. ,, 0-21 0-10 0-75 0-55 1-15 0-75 1 * This dough was too tight. COMMERCIAL TESTING OF WHEATS AND FLOURS. 727 No. 9 Flour. Cold Storage. Visco- meter. Moisture. Wet Gluten. Dry Gluten. True Gluten. Water used in Doughing. Quarts per Sack. Weight of Dough. Lbs. per Sack. 1 Quarterns per Sack. Arrival . . 61 14-52 41-5 14-3 t 550 424-0 97-5 2nd. week 62 14-03 39-0 14-6 12-8 570 426-0 97-9 4th. „ 1 63 14-82 45-1 15-6 — 60 0 435-0 100-0 6th. ,, 64 14-81 45-0 15-7 ■ — 56-5 412-5 94-8 10th. „ 61 14-7 43-2 14-6 — • 560 425-0 97-7 13th. „ 62 13-63 38-55 14-65 — 56-0 427-5 98-3 Hot Storage. Arrival . . 61 14-52 41-5 14-3 55 424-0 97-5 1st. week 68 11-02 40-5 14-0 13-50 57 434-0 99-8 3rd. ,, 70 11-07 40-0 14-0 — 59 439-0 100-9 5th. ,, 73 9-20 42-5 15-2 — 63 435-0 100-5 7th. „ 72 8-0 41-1 15-2 — 66 451-0 103-7 11th. „ 72 7-9 41-7 15-0 — 68 477-0 109-7 14th. „ 72 8-8 42-75 15-03 — 68 452-5 104-7 Colour by Tintometer. Cold Storage. Dry Flour. Pekarised. Crumb. Yellow. Red. Yellow. Red. Yellow. Red. Arrival 0-30 0-18 0-90 0-70 1-3 0-90 2nd. week . . 0-24 0-12 0-90 0-72 1-4 0-91 4th. 0-20 0-10 0-90 0-71 1-4 0-70 6th. ,, 0-21 0-10 0-90 0-70 1-5 0-90 10th. ,, 0-29 0-08 0-86 0-70 1-5 0-86 13th. „ . . 0-20 0-09 ! 0-86 0-68 1-3 0-95 Hot Storage. Arrival 0-30 0-18 0-90 0-70 1-3 0-90 1st. week . . 0-34 0-20 1-4 1-0 1-6 1-0 3rd. ,, 0-22 0-20 1-2 0-90 1-5 0-72 5th. ,, 0-20 0-10 0-90 0-70 1-5 0-76 7th. „ 0-28 0-10 0-78 0-52 1-5 0-59 nth. „ 0-23 0-10 0-86 0-70 1-5 0-84 14th. ,, 0-24 0-13 0-80 0-69 1-3 0-95 I 728 THEiTECHNOLOGY^OF BREAB-MAKING. The lb. samples stored in tins were examined on June 29. In the following tables are given the percentages of gluten and moisture, water-absorption by viscometer, and colour of dry and Pekarised flour respec- tively, on arrival, at end of first week and last w^eek (approximately four m onths). Comparison of Flours on Arrival, First, and Last Week. Glutens. Hot Storage. Cold Storage. Tinned Store. Arrival. First Week. Last Week. First Week. Last Week. Last Week. Wet. Dry. Wet. Dry. Wet. Dry. Wet. Dry. Wet. Dry. Wet. Dry. 38-5 13-2 37-0 12-9 *30-4 11-3 35-7 12-2 35*9 12*2 *19-9 6-5 43-7 14-3 42-0 14-4 *31-3 12-3 38-5 13-7 47-8 14-5 *30-0 10-5 34-8 12-3 32-5 11-3 34-5 1109 31-5 10-2 33-0 10-7 37-5 12-5 30-3 1L6 340 11*7 30-0 11-4 32-2 11-8 3M 10-5 30-0 10-9 40-2 13-3 41-0 140 42-4 14-4 37-8 14-5 45-7 13-2 42-5 13-9 42-3 13-5 44-5 131 441 14-2 40-5 14-5 42-5 12-8 450 13-6 45-1 14-6 43-0 14-6 44- 1 15-7 44-0 15-0 450 14-8 41-0 14*6 40-2 13-4 40-5 14-5 41-0 13-8 351 131 37-4 13-2 42-7 15*6 41-5 14-3 40-5 140 42-7 15-0 39-0 14-6 38-5 14-6 38-5 13-2 * These Glutens were decomposed and very difficult to wash. Water Absorption and Moisture, on Arrival, First, and Last Week. Viscometer in Quarts per Sack. Moistures. Hot Store. Cold Store. Tinned Store. Hot Store. Cold Store. Tinned Store. Arriv- al. First Week. Last Week. First Week. Last Week. Last Week. Arrival. First Week. Last Week. First Week. Last Week. Last Week. No. 1 57 58 69 58 55 52 15-33 12-91 8-95 14-7 15-4 *14-5 2 59 60 70 59 57 52 14-73 12-28 7-85 14-15 13-95 *14-5 3 63 70 74 65 63 63 12-81 14-40 8-07 11-92 13-2 *16-4 4 72 75 81 74 72 68 12-65 10-00 * 12-56 * *12-8 5 68 68 75 69 65 62 13-06 11-70 8-5 13-0 13-08 *13-0 6 70 70 76 70 65 62 12-67 11-75 8-60 13-2 13-51 *12-9 i ” 1 7 69 69 76 69 68 60 12-61 10-72 8-20 13-05 13-82 *12-8 1 8 62 65 73 64 61 59 14-40 10-65 7-25 13-70 14-0 *14-2 )» 9 61 68 72 62 62 62 14-52 11-02 8-80 14-03 13-63 *14-7 * These were all more or less musty. COMMERCIAL TESTING OE WHEATS AND ELOURS. 729 Comparison of Colour Readings, Eirst, and Last Week’s Dry Elours. Hot Storage. 1 Cold Storage. 1 Tix.xed Store. ; ! Arrival. First Week. Last Week. First Week. Last Week. Last Week. 1 Yellow. Red. Yellow. Red. Yellow. Red. Yellow. Red. Yellow. Red. Yellow. Red. 1 No . 1 0-28 0-21 0-22 1 0-12 0-20 014 0*18 002 0-20 0*17 0-30 0-20 „ 2 0-30 0-22 0-20 018 0-21 016 0-20 0-09 0-21 010 0-30 0-22 „ 3 0*30 010 0-20 Oil 0*19 0-09 Oil 009 0-10 0-09 0-28 0-20 „ 4 0-29 0-20 0-25 0-20 0-22 0-23 010 010 0-24 0-25 0-30 0-20 „ 5 0-30 0-21 0-29 012 0-20 010 0-27 0-09 0-27 010 0-34 0-20 „ 6 0-30 0-22 0-30 014 0-22 0-09 0-30 0-05 0-26 0-88 0-36 0-26 „ 7 0-38 0-30 0-31 0-20 0-27 010 0-31 016 0-28 0-22 0-39 0-30 „ 8 0*34 0-20 0-30 017 0-22 0-09 0-20 0-10 0-20 0-09 0-31 0*20 „ 9 0-32 0-21 0-34 0-22 0-21 0-13 0-24 012 0-20 010 0-30 0-21 1 Colour Comparison, Pekarised Elour. Hot Storage. i Cold Storage. Tixned Store. Arrival. First Week. Last Week. First Week. Last Week, i Last ' \Yeek. Yellow. Red. Yellow. Red. Yellow.' Red. Yellow. Red. Yellow. Red. i Yellow. Red. No . 1 0-81 0-82 0-73 0-80 0*80 0-65 0-91 0-80 0-80 0-50 0*80 0-60 . 2 0-82 0-84 0*71 0-80 0-90 0*60 0-80 0-62 0-90 0-80 0-80 0-83 „ 3 10 0-81 0-80 0-63 0-80 0-56 0-70 0-53 0-80 0-60 0*76 0-61 „ 4 10 10 10 0*80 0*91 0*70 iO -92 0-71 0-89 0-70 0-84 0-72 ,, 5 0-88 0-71 1-3 0-91 0-90 0-60 0-90 0-80 0-90 0-75 0-90 0-61 „ 6 0-94 0*71 1-2 0-99 0-90 0-65 0-90 0-81 0-90 0-70 10 0-70 „ 7 109 0-91 1-3 10 10 0-70 0-90 0-80 10 0-80 M 0*90 „ 8 0-80 0-71 1-5 0-99 0-75 0-56 0*71 0-60 0*80 0-69 0-80 0-70 „ 9 0-90 0-71 1-4 10 0-80 0-69 0-90 0-74 0-86 0-70 0-87 0*70 Yield of Eermented Dough, Lbs. per Sack. Cold Storage. Hot Storage. Arrival. First Week. Last Week. First Week. Last Week. No. 1 420 0 425-0 407-5 422-5 447-5 „ 2 4170 424-0 415-0 422-5 440-0 „ 3 435 0 442-5 425-0 446-0 472-5 „ 4 460-0 460-0 451-0 471-5 475-0 „ 5 442-5 442-0 427-5 448-5 465-0 ” ^ 441-5 445-0 437-5 445-0 480-0 „ 7 446-5 469-5 445-0 454-5 472-5 „ 8 426-0 430-0 425-0 434-0 455-0 „ 9 424-0 426-0 427-5 434-0 452-5 730 THE TECHNOLOGY OF BREAD-MAKING. Yield in Qdakterns per Sack. Cold Storage. 1 ! Hot Storage. | 1 Arrival. First Week. Last Week. First Week. Last Week. No. 1 96-6 97-7 93-7 95-9 102-9 „ 2 960 97-5 95-4 97-1 101-2 1 1000 101-7 1 97-7 102-5 108-6 „ 4 105-8 105-8 i 103-7 108-4 109-2 1 „ 5 101-7 101-7 98-3 103-1 107-0 1 „ 6 101-5 102-3 lCO-6 102-3 110-4 1 „ 7 102-6 104-0 101-9 1C4-5 108-6 I „ 8 97-8 98-9 97-7 99-8 104.6 9 97-5 97-9 98-3 99-8 1C4-7 In all cases the hot stored flour worked best and produced the better loaf, and the yield was much greater. Record of Baking Characters of Flours. No. 1. Cold stored flour : Showed signs of newness ; nice feeling dough, but weak ; producing loaf of poor volume ; gradually improved till April 2, when it stood well, producing fair volume loaf ; about May 18 showed signs of deterioration, not standing so well ; also produced loaf of inferior flavour ; in June did not work so well ; poor volume, bad colour. No. 1. Hot stored : Showed newness of flour, runny and small. March 25, greatly improved in stability and water absorption, produc’ng loaf of good volume and texture. May 18, still improved, worked well, producing fair volume, good texture, and nice colour loaf. June 9, deteriorating ; does not work so well ; poor volume. No. 2. Cold storage : Rather weak, but good colour. March 17, stands better, worked well, rather small, fair texture in crumb. May 18, much deteriorated ; worked fairly ; produced loaf of bad flavour. June, not so good as previous baking ; poor volume, close dead colour in crust, musty flavour. No. 2. Hot storage : March 11, dead feeling dough, a little soft ; loaf was close ; small volume. March 25, greatly improved, worked well, pro- ducing loaf of good volume and texture. April 5, still improved ; stands well, better volume. May 20, not so good, going back in quality. June 9, does not work or stand well ; poor volume loaf, bad colour and texture. No. 3. Cold storage ; Makes a good dough, stands well, good-shaped loaf, even texture ; keeps good character throughout. April 2, worked well, but not so good as hot-stored flour. May 18, losing its good properties ; poorer in volume, rather redder in crust. June, worked only fairly ; slightly musty. No. 3. Hot storage : Worked well, nice and springy ; produces nice loaf in texture, and colour of crumb and crust. April, works well, but gluten seems a little short. May 20, worked well ; not quite so springy, fair volume, good texture loaf. June, gluten seems brittle in moulding, fair volume, good colour loaf. No. 4. Cold storage : Heavy working, no spring. April, worked better ; no improvement, slightly musty, close. May 18, dark and musty. No. 4. Flot storage : Bad working, no life ; close, poor volume loaf. March 25, worked better ; little spring, poor volume. April 5, bad colour, no spring, close ; poor volume and musty. COMMERCIAL TESTING OF WHEATS AND FLOURS. 731 Nos. 5, 6, 7. Cold storage : These are all hard flours and worked very similarly, behaving well throughout. March 11, worked well ; good lively dough, produced good volume, a little holey ; good colour loaf. April 2, worked well ; good volume and texture loaf. May 18, first-rate working, stood well ; good volume and colour. June, not quite so good as previously. Nos. 5, 6, 7. Hot storage ; These worked well throughout, and improved by storage up to the last, producing good-flavoured and bold loaves. No. 8. Cold storage : Nice springy dough, showed signs of newmess by not standing well ; fair volume. March 17, still shows newness. April 2, much improved ; nice looking loaf, fair texture. May 18, works well ; stands well, good volume, texture, and nice colour loaf. June, not so good. No. 8. Hot storage : March 11, good springy dough, worked well ; hot storage much improved it. March 25, greatly improved ; good volume and texture loaf. April, works well ; stands well, good texture, volume, and flavour. May 18, quite as good as previous baking. June, is losing its elasticity ; not so good volume. No. 9. Cold storage : Good dough, but little soft from newness. March 17, seems more runny. April 2, stands better ; fair volume loaf. May 18, improved ; good volume, fair texture. June, worked heavily, much inferior to hot-stored flour ; rather a close loaf. No. 9. Hot storage : Good springy dough, nice and silky. March 25, much improved ; stands well. April, stands well, produced good texture and volume loaf. May 20, not quite so good. June, worked lifeless ; gluten seems to be decomposing ; poor volume loaf. For the whole of the more minute details the reader is referred to the tables themselves. The following is a summary of the general lessons fur- nished by these experiments ; — For each flour there are three distinct series of observations, viz., those on the cold stored, hot stored, and tinned samples. The tem- perature of the cold stored flour ranged between 47° F. and 60° F., with a mean closely approaching 55° F. The hot stored flours ranged between 72° F. and 98° F. in temperature, with a mean temperature approaching to 84° F. The tinned samples were kept subject to the same temperatures as those which were cold stored. Taking the various determinations in the order given we find that the — Water -absorption by Viscometer fell off slightly in the case of the cold stored flours, the amount of such falling off being most marked with the softer flours. With those that were hot stored there was in each case a very decided increase. In the tinned samples there is a decided falling off. Moistures. — In the cold storage there is no regular change ; what change there is is not great, but some flours have slightly gained and others slightly lost in moisture. These changes are undoubtedly governed by changes in the humidity of the atmosphere. The hot stored flours have all lost very largely. As might be expected, the tinned samples show very little variation. Glutens. — There is here a very marked difference betw^een the behaviour of the soft and the harder flours. Taking first the cold stored flours, the softer ones show a falling off, while the harder ones remain stationary. With the hot stored flours, notwithstanding a loss of moisture, the soft flours show a falling off, wLile the harder ones exhibit a decided increase. With those stored in tins the soft flours have changed considerably in character, and have lost a very large proportion of gluten. Bailing behaviour. — With regard to baking behaviour, a comparative record is given of the quarts of water taken and quarterns yielded per sack. It will be seen that with the cold storage there is in most cases a diminution, wiiereas with hot storage, owing to the diminishing quantity of w'ater present, there is in all cases a greater absorption of w^ater in doughing, and consequently a 732 THE TECHNOLOGY OF BREAD-MAKING. greater yield of bread. The extra water thus taken up is, in most cases, greater than the actual percentage of water lost as a result of drying. In another table is given a record of the general baking behaviour and character of the flours throughout the whole period of storage. Both in cold and hot storage, there is a general improvement of all the flours for the first six or eight wrecks, after which, in the case of the softer flours, there is a falling ofl in quality in the case of those stored in the cold ; but vdth regard to those kept hotter and drier, there is a steady improvement for quite three months, at the end of which the softer flours commence to deteriorate, while the harder flours show improvement quite to the end of four months. Colour Readings . — In the case of the readings on the dry flours, cold stored, there is a decided bleaching action for about the first fortnight, after which, for the next four weeks, there is, as a rule, comparatively little change, but such as there is is in the way of darkening. After the expiry of six weeks the darkening is more marked, but the last readings run lighter than the first. The soft flours are much the most erratic in colour changes. The hot stored dry flours have, as a rule, showed a steady bleaching. The tinned dry flours remained almost stationary, but in some cases showed a slight darkening. Taking next the Pekar test results, these do not show such wide variations as those on the dry flours. The cold stored samples remain practically the same after about the first or second week, during which there is some bleaching. The tinned samples show but little change, and probably, if they had been read every week, there would have been no practicable change, say, after the first ten days. Best Mode of Storing Samples . — These experiments show that great changes may be produced in flour by the actual conditions under which samples are stored ; to form any judgment whatever it would be necessary that storage be arranged for under definite and regular conditions. Among conditions which seem most likely to serve this purpose the following seem essential. The store should be warm and dry, say, at as steady a tempera- ture as possible of 80° F. A portion of the flour should be placed in a small bag, and then this stored in an air-tight tin for purposes of colour testing. A larger portion for baking and other tests should simply be kept in a close textured bag. Sale hy Sample . — The important question which this report raises is whether or not stored samples can in fairness to buyer and seller be taken with eonfidence as an absolute test of the identity or otherwise of delivered bulk of flour. Speaking generally, with hard flours, properly stored, there is very little change, and practically such flours could without much risk be checked against sample, particularly if a sample of the bulk flour be drawn and stored under same conditions as the original sample, for, say, ten days, and then the comparison made. But with softer flour the changes wiiich go on cannot be measured with sufficient accuracy to warrant any very exact judgment being given. If forward sales are to be made by sample, then, in the opinion of the authors, such samples should be stored as previously suggested, and then within from ten days to a fortnight determinations should be made of gluten and colour. If necessary to check bulk against original sample, a properly- drawn bulk sample should be taken, stored for ten days so as to be certain in such case that the flour lias become stable, and then the two tested against each other. In most instances the two samples could, under these con- ditions, be compared against each other, and a reference to the first testing made on the original sample would at once show whether it had undergone serious change. If there were no such change then the comparative test would give definite information and data as to quality of bulk against sample. COMMERCIAL TESTING OP WHEATS AND FLOURS. 733 If the sample had altered, it would be necessary to decide each case on its own merits as to whether any judgment could be formed from the sample. {N. A. Review, p. 408, 1897.) 802. Effect of Keeping Flour on Moisture Content, Snyder. — When samples of flour are preserved three to six months, there appears to be a pronounced change in the moisture content. After samples of flours and milling products had been kept in sealed bottles in a cool place for six months the determined moisture content of all of them averaged about 2*5 per cent, less than the figures for water in the fresh samples. If so great a change in moisture had actually occurred, the calculated and the determined heats of combustion, as obtained by the calorimeter, would differ from the heats of combustion determined for the preserved samples. But the difference be- tween the determinations made on samples that had been kept three months and those made on the fresh samples was no greater than the difference between duplicate determinations made on the same sample. It would seem, therefore, that the apparent loss of water in the sample preserved is simply due to the hydration of the gluten proteins ; that is, to the fact that the water is held in such a way that it is not driven off by the ordinary method — ^.e., drying at 100° C. The . experiments suggest that in the mixing and other stages of bread-making the hydration of the gluten proteins is one of many important changes which take place in flour, and that water plays a chemical as well as a physical part in bread-making. Snyder’s observations do not agree with those recorded in the preceding paragraph. In the case of samples preserved in tightly fitting tins, the moisture varied but slightly from the commencement^ of the tests therein recorded to the conclusion. [Bull. 101, U.S. Dept, of Agric.) 803. Baking Tests. — In comparing the relative value of baking tests with those made by analytic methods, it should be borne in mind that the latter are obtained by processes in which all disturbing influences are so far as possible eliminated, whereas in baking tests the quality of the yeast, temperature of working, etc., are all disturbing elements. As seen by pre- ceding results quoted, the colour and other characteristics of the bread are affected by differences in the mode of performing backing tests. In baking tests, again, the individuality of the baker must largely come into play, as he will naturally treat the flour in the manner most nearly comparable with his own general mode of working. As no tw^o bakers work exactly alike, one set of results may not quite agree with those obtained by another baker w'orking in a somew hat different manner, and with not altogether the same objects in view'. There follow' a number of series of important baking and other tests made at different times, together with a description of the mode of w'orking employed. They are useful, not merely for the data they afford, but also as illustrations of different experimental methods. 804. M‘Dougairs Tests. — In Chapter XIV., paragraph 424, an account of various milling tests by M‘Dougall Brothers is given ; the table on page 734 embodies the results of baking tests made by them on the flours ob- tained. The quantities used were in each case 1 sack (280 lbs.) of flour ; 30 lbs. of liquid potato ferment ; 1 lb. distillers’ yeast ; and 3^ lbs. of salt. The colour, flavour, and texture, are expressed by a series of numbers, the highest quality being represented by the highest number. This system of giving “ marks ” for qualities such as these is now w'idely adopted. In judging bread for various competitions, as w'ell as for flour testing purposes, scales of marks are used for the valuation of those qualities which cannot otherw'ise be expressed numerically. From these experiments, M‘Dougall Brothers 734 THE TECHNOLOGY OF BREAD-MAKING. conclude that yield of bread does not mainly depend on the quantity of gluten contained by the flour, but principally on its degree of dryness. A feature of these experiments, which has caused considerable contro- versy, is the very high position they give to Indian wheats, particularly as the Report was prepared at the request of the Secretary of State for India. Baking Tests on Single Wheat Flours^ — M‘Dougall Bros. Yield of Bread when cold. Percentages. Colour, Taste, and Texture. Wheat. Water used. Per- centage of Bread to Flour. Per- centage of Water to Flour. Colour, Exterior. Colour, Intel ior. Texture. 5 S General Char- acteiistics. Indian (fine soft white) Lbs. 141-4 Lbs. 364-0 130-0 50-5 10 11 8 7 11 Do. 149-6 367-5 131-2 53-4 13 13 9 9 12 Indian (superfine soft white) 141-6 372-0 133-0 50-6 8 10 9 7 10 Do. 148-0 362-0 129-3 52-3 12 13 10 9 11 Indian (average hard white) 141-0 370-5 132-4 50-8 6 7 10 7 7 Do. 149-6 365-0 130-3 53-4 10 9 10 9 9 Indian (average hard red) . . 145-2 376-6 134-5 51-8 5 7 10 7 6 Do. 147-4 365-0 130-3 52-2 9 9 10 8 8 English 130-0 352-0 125-7 46-4 13 12 10 13 10 Australian 134-2 355-4 126-9 48-0 12 12 10 12 11 New Zealand . . 132-0 349-0 124-6 47-1 12 12 9 12 10 Californian 136-8 364-0 130-0 48-9 12 12 9 12 10 American (Winter) . . 130-0 346-0 123-5 46-4 13 12 10 12 11 American (Spring) . . 130-0 354-0 126-4 46-4 8 10 12 10 9 Russian (Saxonska) . . 130-0 356-0 127-1 46-4 8 9 13 9 9 Russian (Taganrog) . . 145-4 354-5 126-6 51-9 10 11 12 9 9 Egyptian (Buhi) 136-8 362-5 ' 129-3 48-9 7 6 7 6 5 Egyptian (Saida) 144-4 358-0 127-7 51-6 6 4 6 4 4 805. Clifford Richardson’s Baking Tests. — In 1884 Clifford Richardson presented to the American Government a report of the results of baking tests made of American flours. The objects of these tests was largely to investigate M‘Dougairs results on flours from American wheats. Richard- son prefaces his results by stating that “ using flour under various condi- tions, it was found possible to vary the yield of bread per 100 lbs. of flour as much as 15 lbs. The conditions upon which this variation depends are largely physical, and include — Percentage of water used in the dough. Size of the loaves. Temperature of the oven. Time of Baking.” In further illustration of this point, Richardson gives a table (page 735), showing the extent to which the variation in yield is dependent on the per- centage of water (other conditions remaining the same), the size of the loaves, difference of temperature, and on the time of baking. Richardson further points out that “ a dough made with any American flours, and as small a percentage of water as was used by the M‘Dougalls, Avould be altogetlier too stiff for successful results.” Richardson may very possibly have overlooked the 30 lbs. of potato ferment used bv the M‘Dou- COMMERCIAL TESTING OF WHEATS AND FLOURS. 735 galls ; adding this on to the water taken for American flours, the total is 160 lbs. or 16 gallons of liquid per sack. This quantity is quite sufficient for crusty cottage loaves such as were made by the M‘Dougalls ; whereas in Richardson’s experiments a slack tin or pan dough is throughout used. The difference is largely due to difference in the character of the bread commonly made in America and England respectively. This point should always be borne in mind when comparing results obtained by observers in the two countries. A further important bearing it has is this — the flour, which will take a relatively high proportion of water for slack or tin dough, is not neces- sarily that which will also take a relatively high proportion when used for crusty cottage bread. Flours A\dth soft ductile glutens will often take a very large quantity of water, provided the dough is supported in a pan for baffing, while they may in the stiffer dough be comparatively unable to stand vithout support, and so make a flat, runny loaf. Variations in Bread Yield — Richardson. Dependent on Percentage of Water used (other conditions being the same). Dependent on Size of Loaves. Dependent on Difference of Temperature. Dependent on Time of Baking. Per cent. Yield of No. of Yield of Tem- Yield of Time, Yield of of Water. Bread. Loaves. Bread. perature. Bread. Minutes. Bread. 54-5 134-0 1 loaf 138-6 249 ° 136-9 50 134-6 58-4 136-9 10 rolls 129-6 230 ° 140-8 30 140-2 62-1 144-9 — — — — — — 62-1 145-5 — — — — — — In all American systems of flour-testing which have come under the authors’ personal notice, the baking tests are made on tinned bread. This, doubtless, gives the best results for flour as used in America. It is suggested that American millers, who export to this country, should also have their flours tested by methods based on the production of crusty bread such as is most generally made in England. Richardson made a dough with the whole of the water, allowed it to rise till the outer pellicle was just cracking, then re-kneaded it into loaves, which were put in tins or pans and then baked. The table on pages 736 and 737 gives the results of his experiments. 806. Flours collected in America. — In 1893 one of the authors made an extended tour through the United States and Canada, collecting personally a number of typical flours, and subjecting them to commercial analysis and baking tests, particulars of which are given on page 739. The various analytic tests need no further explanation, but it may be mentioned that in the baking tests the method employed was the making of an off-hand dough of tight- ness sufficient for crusty cottage loaves. The quantities taken were one kilogram of water and sufficient flour to make a dough of requisite con- sistency. The water has been calculated to quarts per sack ; other data are also given. Subjoined is a list of the flours, together with particulars of the variety of wheat from which each was produced. Baking Tests on Various American Flours. — Clifford Richardson. Ill the following series of baking tests, in each experiment there were taken of water G50 grams, milk 500 grams, salt 25 grams, yeast 10 :''ams, with the weight of flonr as under : — 736 THE TECHNOLOGY OF BREAD-MAKING. o 00 CO CP CD pH o 00 t- O ; oi 1 ^9 1 ^ 1 1 CD 1 9 1 3 1 • P O 1 6 i I-H 1 CP 1 CP 1 pH I 1 4 1 4 1 6 1 S pH pH pH I-H I-H (M CP uo 00 o CP CO CO 1 1 I-H 1 9 1 9 1 9 1 1 9 1 9 1 9 1 CO 1 Ol 1 6 1 4 1 CO 1 CD i 1 CD 1 CP 1 Pi CO CO CO CO CO CO CO CO Ol P o CO o o CD 00 O Ol Ph Pro- .2 CO 1 6 1 CP 1 O 1 2 1 S 1 9 1 CP 1 ^ 1 1 Ol 1 1 CD 1 Ol 1 9 1 o 1 9 1 O 1 pH c lO , uo , CD , CO , CO , o , o n- 9 1 9 1 9 1 9 9 O rH i-H I-H pH Ol ' I-H 1— H 6^ Xf o 00 00 00 00 CD o lO c *9 1 9 1 ^ 1 9 1 9 1 9 1 1 9 1 9 1 s ^ 1 Ol 1 Ol 1 Ol 1 Ol 1 1 4 1 bi 1 Ol 1 "-9 t- Ol CO 9 9 oo uo 9 e- I-H CO 9 9 9 o' =2 4^ cb o lb lb bi bi 4 4 1 cb 00 !>> rfi 4 ub 1 o CO CO CO CO CO CO CO CO CO CO 1 fo CO CO CO CO CO 1 CO r-H 1 i-i ^ r-H rl fH pH I-H I-H i-H r-H r-H I-H HH hH OP uo T+l ZO O CP ^ 01 t- o Ol 00 lO 00 CO hH o tab'^ (M CP lo Ttn Ttl lO lo CO lo CO 1 CP O 00 CO CO 00 o 1>- t- 9 9 1 00 1 9. p of oi Ol 01 of of of of of of of of of of of of Ol Pi m O d 00 -— 1 CO CO 9 cp 9 9 9 9 9 CD GC 9 9 9 V. ;o o cb lO ^ do 4 O OP ub 4 4 bi 6 CP bi do 4 M Ttl TtH hJH CO CO Tf CO TfH -rtl ''t CO Ttr CO pH fH pH I-H I-H r-H I-H rH I-H I-H ^ I-H r-H r-H hH pH -t-= o CO o CO CP CO CO IT- O 00 CD I-H 00 O 00 'itl CD CP sc-g o CO CO o Tt< »0 CO CD CO T^l 00 CO CP CO hH 00 00 Oj h-i 00 CP CP 00 00 00 00 00 OO 00 CP 00 CP 00^00 oo_^cp 99 c4 c4 Ol Ol of of of of of of of of of of of of of of of 0 Q O 0 o o o o o o o o o s d 1 1 00 CO CO CD O uo UO 1 1 IT- 00 00 O 1 1 'o > (M CO CO CO TtH CO 1 1 H c ) ° (M Ol 01 Ol Ol 01 Ol 01 ' ' Ol Ol Ol 01 Ol S; »0 lO lO o lO lO lO lO lO lO O UO UO UO uo uo uo X o c3 C ^ TjH lO uo CO Tfi •rii^ uo ^ r- O PC o lo o O O o o lO Ol o uo O I-- o uo a> cc C! c COO o o lO o o o o o uo o o hH O o o 1 ’S •S S 1 Ph P- 1 -( pH o ^ rl r-a ^H I-H o ^ ^ rH ^ hH hH b b I hp c •£ (M O 00 CO oo Ol CP PO 00 r-H Ol CP HH 00 1-1 Ol ) l-H CO Ol Ol I-I CO lo CO CO CO I-H hH Ol I-H Ol I-H CO CO Ol 'd C lO o O uo lO lo o o o o lO I-H lO t- o lO uo CD o jXt C CO o UO Tt CO ^ CO O CO CO CO tJh uo CO lO " 1 3 d (M CO 01 Ol Ol Ol 01 CO Ol Ol Ol Ol 01 Ol Ol Ol Ol CO . 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COMMERCIAL TESTIXG OE WHEATS AND FLOURS. 743 I (K S >5 S R ' © © « > > o ? ^ -ji m rlJ . >> © o ^ 3 r- > ^^3 c3 , 2 * Z2 2 rS 3 . bJD3 2S 2 O ;h CO §1 (/} —I 2 ^ r— ‘ ^ tH . o o 2 O K O) >> -o ^ ^ .^o §3 0.O W 8 1 s o GO o o 04 o o o o + oi ; GO u- U' o 04 6 rE 6 o 6 6 o rE o . 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CoLOUH Marking. — Patents : Maximum, 1 ; Medium, 1 -5 ; Minimum, 2. Straights : Maximum, 2-5 ; Medium, 3 ; Minimum, 3-5. Clears : Maximum, 4 ; Medium, 5 ; Minimum, 6. 2nd. Clears : Good, 7 ; Poor, 8. Low Grades and Red Dogs : 9 and 10. The general characteristics of the flour such as Colour quality. Elasticity, etc., are described under the headings “ Doughing Test ” and “ Remarks on Loaf.” For convenience colour is marked numerically as shown, but full straights will usually run one or two figures better than indicated by the nomenclature used. Volume (expressed in cubic inches) indicates elasticity or rising power, showing whether the sample is in proper baking condition or has the ability to produce a good sized loaf. Twelve ounces flour used in each loaf. Weight of loaf when taken from oven (bread yield) expressed in ounces decimally. Amount of water used (absorption) indicated decimally. Each loaf is made according to our standard formula with identical amounts of all ingredients except water, and kneaded exactly alike by automatic machinery, sponge boxes and ovens being controlled at uniform temperature and the following items being recorded : Ounces of flour. Ounces of water, Grains of yeast. Grains of salt, Grains of sugar. Grains of lard. Temperature of flour. Temperature of water sponge, Temperature of sponge box. Time for sponge to rise. Amount of kneading. Time for first rising of dough. Time for second rising of dough. Time for third rising in oven, Temperature of oven when put in. Temperature of oven when finished. Time for baking. Under “ Additional Data,” such data or special tests as Ash, Acidity, Crude Wet and Dry Gluten, True Gluten, Gliadin, Glutenin, Moisture, Starch, Soluble Carbo- hydrates, Fibre, Oil, Soundness, Odour, Miscroscopic Tests, Granulation, Minutes of Fermentation, etc., are entered.” 809. Baking Tests, Thatcher. — Thatcher has recently summarised the various methods proposed for the testing of flour, and describes those recom- mended and adopted by him in the laboratory of The Washington Agricul- tural Experiment Station, U.S.A. The following is a description of his mode of making baking tests ; — Flour Yeast Sugar Salt Water Quantities taken. 340 grams. 10 „ 12 „ A sufficiency. These were then kneaded in a special machine for twenty minutes, so arranged as to maintain the dough at a temperature of 90° F. for that time. The dough was then transferred to a greased tin, and placed in a proving box or cupboard maintained at 90°. Here it was allowed to rise until it just touched a tin strip laid across the top of the tin. The tin was then transferred to an electric oven heated to 400° F., and baked for forty min- utes. The bread was allowed to cool for thirty minutes, after which the weight and volume were determined. The latter was effected by measuring in a cylindrical box with seeds. Thatcher concludes that it is impossible to form final conclusions as to the baking quality of a flour from the results of a chemical analysis alone! Further, he is of opinion that no single test which was tried is capable of giving conclusive evidence as to the baking quality of flour. Any such processes as have yet been suggested must be supplemented by a baking test if final and accurate conclusions are to be reached. [Jour. Amer. Chem. Soc., 1997, 910.) 810. Baking Tests, Method employed by the Authors. — The quantity of flour taken for a baking test may vary according to the custom and require- ments in any particular district. Usually, however, it is desirable to keep the quantity as low as practicable, so that a test may be made on a small sample : at the same time the loaf should be of a fair size, so as to compare 746 THE TECHNOLOGY OF BREAD-MAKING. as well as possible with the bread made for commercial purposes. The authors employ the following quantities, which answer well for general purposes. Quantities . — Flour . . . . . . 560 grams = 19*71 oz. Water as per Viscometric Absorption, or otherwise deter- mined. Salt . . . . . . 6 grams. Compressed Yeast . . 10 grams. The metric system of weights is adopted because of its greater simplicity and the readiness with which exact weights can be determined. The quan- tity, 560 grams, is 2 grams for every lb. of flour in the sack, so that one half the weight of any constituent or product is without any further calculations the weight in lbs. that would be obtained proportionately by treatment of the sack of flour. The resultant loaf of bread usually weighs from 1 J lbs. to If lbs., and although less than the weight of a 2-lb. loaf, is yet sufficiently near to enable a comparison to be instituted. Bearing in mind that the proportions of water used vary very considerably in different parts of the United Edngdom, the authors, for general tests, have adopted the plan of making where possible three separate bakings on each flour, distinguished respectively as a, b, c. For b, what is believed to be the best quantity of water is employed. This may be determined by a water-absorption test, controlled by the viscometer or otherwise. It will be remembered that that instrument gives results in quarts per sack ; and as a quart weighs 2J lbs., the number of quarts X 5 gives the weight in grams or volume in cubic centimetres of water that must be taken to the 560 grams of flour. Fora, 20 grams (equivalent to 4 quarts) less water is taken than in b : while in c, 20 grams more water is added than used in b. The three tests, therefore, represent quantities of water with differences of a gallon to the sack between each, and cover all variations in quantities for ordinary bread- making. Another advantage of testing in this manner is that it provides for those flours which fall off very much during fermentation. In other words, some flours will not in reality take as much water as might be judged from the tightness of the dough when first made. Conversely, other flours fall off less than the normal in fermentation, and evidently require more water than is indicated by the character of the dough at the moment of preparation. Where one test only is made, a very frequent comment is — this flour would have been better with a quart or two quarts more [or less] water.' If a series of tests is made, one of them is likely to closely agree with the quantity of water best suited to the flour throughout its whole fermentation. If thought preferable the difference between each test may be taken at some other figure than the gallon. Mode of Fermentation. — First weigh out the flour, and put it in a pan of sufficient size (for whieh purpose an ordinary white pudding-basin, 8 or 9 inches internal diameter, answers well). Next take the temperature of the flour, and if anything below 70° F., carefully warm it until that tem- perature is reached. A convenient method in the testing laboratory of doing this is to stand the basin eontaining the flour in hot water, and stir the flour continually with a spatula until sufficiently warm. A “ ferment is next made with the whole of the water to be used. This water may be either measured or weighed ; if the former course be adopted, the measures should be specially graduated to deliver grams of water at 100° F. It has been found convenient to have the ferment, when set, at 90° F. ; the initial temperature of the water should be so adjusted by experiment as to give COMMERCIAL TESTING OF WHEATS AND FLOURS. 747 this temperature at the finish ; usually about 10° is lost in this operation, and therefore the water may be taken at 100° F. Make a hole in the middle of the flour (bay), and having the water in a measure, break down the pre- viously weighed yeast into the water, and pour the whole into the bay. Work carefully a little of the flour into the liquor so as to form a ferment of the consistency of a thin batter : this ferment, as above stated, should have a temperature of 90° F. For the fermentation there should, when practicable, be provided a proving cupboard, so arranged as to just take, on a series of shelves, a number of these basins, all of which must be labelled and marked. By some convenient means the temperature of this cupboard should be maintained at about 85° F. ; this may be done either by the injection of a jet of steam, or the well-known plan of a small atmospheric burner at the bottom of the cupboard, with a vessel of water over it. The temperature of this cupboard should be under control, and must be kept uniformly at the desired degree. Cover the basin containing the ferment with a light linen cloth, and place it in the proving cupboard for one hour ; at the end of that time the ferment will be “ ready,” and should have nicely dropped. Add the finely- powdered salt, and stir in the flour and salt into the ferment with a bone spatula. Knead thoroughly either by hand, or preferably in one of Werner and Pfleiderer’s small doughing machines, taking care that no loss occurs during the operation, and that the dough is made perfectly smooth. Return to the proving cupboard, and after one hour well “ knock down ” the dough ; place again in the cupboard for half an hour, and then weigh the dough accurately. The bread may be baked in a tin, or for most purposes, pre- ferably, as a cottage loaf. Mould, and allow to sta-nd for a few minutes if necessary. Moulding should, if possible, be done vithout dusting flour ; when any is used, a quantity should be weighed, a.nd that remaining after the moulding of each loaf again weighed, and note made of the quantity used. This should not exceed 2 grams per loaf. Bake in an oven, the temperature and behaviour of which is knovTi, and, if possible, together with loaves of a familiar flour, so as to be able to judge the comparative tendency of the flour to take the fire. When baked, allow the bread to stand twelve hours — say over night — and then weigh. Notice whether the bread happens to be burned at the bottom, and if so make a note, as the weight will thereby be affected. Note the character of the loaf, compared vflth a standard or known sample ; whether of good volume, bold and well shaped, twisted or flat ; also the colour of the outer crust, and likewise in the partings between the top and bottom of the cottage. If wished, the volume of the loaf may be determined by means of a, cylindrical measure sufficiently large to hold it completely. The loaf is placed in this, and rape seed or other small seed added to fill the measure, the upper surface of which is then “ struck.” The quantity of seed used is then measured, preferably in a vessel graduated in cubic centimeters,, and also the quantity of seed similarly required to fill the measure without the loaf. The difference gives the volume of the loaf. Compare the appearance of the three loaves side by side, and decide which represents the bread from the best size or stiffness of dough. Note also whether there is a great difference betw'een each, as some flours stand an excess of w'ater over the normal far better than others. Next cut the loaf in the direction of greatest outline, and observe the colour, texture, pile, and sheen of crumb ; also moistness odour, and flavour of crumb. (It should be borne in mind that the flavour of a small baking test is not an absolute criterion of that of bread regularly made in full-sized batches.) The colour may be measured and registered when thought 748 THE TECHNOLOGY OF BREAD-MAKING. desirable by means of the tintometer modified by the addition of de-focussing lenses. If wished, a system of giving marks for colour, texture, fiavour and other characteristics may be adopted. In fixing these a maximum and minimum should be decided on, and then the loaf being tested should have its intermediate position indicated as accurately as possible by the number of marks given. If it is desired to keep a permanent record of its size, the cut loaf may be placed on a sheet of paper, and marked round with a pencil. This may be done on a leaf of a note-book, and the other data placed on the opposite page. (See Fig. 109.) The following are given as an example of how baking tests may be entered in the note-book, together with deductions made therefrom ; — Description of Flour— High-Class English Patent. Water absorption by Viscometer — 60 quarts per sack. a. b. c. Flour in grams 560 560 560 Water ,, 280 300 320 Yeast ,, 10 10 10 Salt ,, 6 6 6 — Unfermented Dough in grams 856 876 896 ,, ,, lbs. per sack 428 438 448 Fermented Dough in grams . . 827 850 860 ,, ,, lbs. per sack. . Fermented Dough calculated into loaves 413*5 425 430 of 4 lbs. 6 oz. per sack . . 94*5 97*1 98*3 Weight of Bread, 12 hours old, in grams . . Weight of Bread, 12 hours old, in lbs. per 707 737 760 sack 353*5 368*5 380 Loaves of 4 lbs. each per sack 88*4 92*1 95*0 Colour of bread by Tintometer — -Yellow . . 1*35 1*35 1*35 „ „ ,, Red .. 0*70 0*75 0*75 In the above results the mode of determining lbs. per sack is self-evident : quantities in grams are simply divided by 2. Calculated loaves per sack from dough are obtained from lbs. per sack by reducing to ounces and dividing by 70 (ounces = 4 lbs. 6 oz.). The readiest way of performing this calculation is to multiply weight in grams by 8 and divide by 70, thus : ^ ^ = 94-5 loaves per sack. 70 ^ The results obtained as yield in bread by calculating at 4 lbs. 6 oz. on the dough are more trustworthy than those by direct weighing of the bread itself, as single sample loaves will vary more in weight from the normal than does a full batch calculated on the weight of dough. 811. Special Apparatus for Baking Tests. — When baking tests are being conducted on a large scale, certain special appliances enable results to be obtained not only with greater speed, but with more exactitude. For water measuring purposes it is very convenient to employ a large burette and reservoir similar in character to that figured No. 103 for making viscometric determinations. The burette should have a capacity of 400 C.C., and sliould be provided with a large way tap. The reservoir should be open at the top, but provided with a cover : a number of tests having COMMERCIAL TESTING OF WHEATS AND FLOURS. 749 to be made, sufficient water should be in one operation adjusted to the right temperature, and used for the whole series that are started off together. Wliere it is possible to bake sample loaves with a batch of ordinary bread, that forms one of the best modes of procedure. It has the great advantage for crusty bread that a better shaped loaf is produced than when single loaves, or some two or three only, are baked in a small oven. For laboratory work, however, a special oven is usually necessary. For this purpose the authors have for some time used, and with very satisfactory results, a special type of gas oven. The oven is fitted with a tiled sole, and a baking chamber entirely shut off from the gas flame and products of com- bustion. At the front, immediately underneath the oven doors, four lines of gas burners enter beneath the sole ; from this hot air chamber a series of iron pipes convey the heat up around the sides to the crown of the oven, the whole of the oven is lined on the outside with slagwool, reducing the escape of heat to a minimum. Each line of burners can be regulated separ- ately ; those in the middle give an increased bottom heat, while those on the outside raise the heat of the crown. For baking tests it is well to line the sides and back of the oven with tiles to act as upsets, as the bread is better baked with top and bottom heat only. The oven bakes very evenly, is very steam-tight, and clean and inexpensive to use : in fact, is well adapted all round for this purpose. Another useful form of testing oven is one heated by electricity. The temperature is well under control, and the bread is well and evenly baked. 812. Special Series of Baking Tests on British Flours.— Following are the results of examination of a number of British milled flours, the quality of which is indicated by the names attached. They are set out in the tables on pages 751 et seq. In Fig. 109 are given the sectional outlines of a few loaves, mostly selected from this series and drawn to a reduced scale (compare page 748). The sections marked a contain least water, b another 4 quarts, and c 8 quarts more than a. The following are particulars of each loaf : — Water taken for b Test. Quarts per Sack. No. 1. Strong British Milled Patent Flour . . . . 60 ,, 2. Minnesota Straight . . . . . . . . 70 ,, 3. Spring American Second Patent . . . . 63*5 ,, 4. Number 2 Winter Wheat Patent . . . . 56*5 ,, 5. British Milled Household Bread Flour . . 58*0 ,, 6. Straight-Run British Bread-Making Flour . . 60*0 ,, 7. British Milled Bakers’ Grade Flour . . . . 62*0 ,, 8. English Wheat Flour . . . . . . . . 56*0 813. Alternative Scheme for Baking Tests. — For the convenience of those who prefer to work entirely with English weights the following direct- ions for making a baking test are given : the quantity of flour used, 3 lbs., produces from 4 lbs. to 4J lbs. of bread. This may be baked either in tin or cottage loaves. First determine the water-absorbing capacity of the flour either with burette alone, or in conjunction with the viscometer. Make a dough either of full viscometric strength, or as much tighter as may be necessary to suit the requirements of the district. This can readily be done by deciding once for all on a constant deduction from the water-absorbing capacity according to the sixty-seconds standard. 750 THE TECHNOLOGY OF BREAD -MAKING. Fig. 109. — Sectional Outlines through various Loaves. With 7 lbs. of flour, each ounce of water used is equivalent to one quart per sack. For tests on 3 lbs. of flour the water in ounces, equivalent to quarts per sack, is obtained by multiplying by i : thus 50 quarts per sack Analytical and Physical Tests on Special British T’lours. 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T3 O o bC a U ^ O C3 W) o q=l W) bO 3 O I? a 03 bO Hi o >5 P CO d f c s ^ o ^ a 5 2:=i 53 S3 P c3 ‘S -Go •3 (S CD '+H ^ O c fi © .a d -I at .a s=> o o - bC © G .3 g .p I? a © c3 ^ 2^ II g P o k C >-£ © C l| .22 “ a b p bO ^ fl o qH bC W) § a 'a -a i S'P ^ £ ° c§ P bc'« 43 - tc « a p O • U O P P2 9 > c3 bO © s . CO © - 1.3 V|3 G oo © "o a °3 g a ©*' " c3 c^ b o- Pi bc o r/r.22 43 © 0.2 u o © o 32 P3 -5 - -^1- § ^rp §tJ..Q a " a © o 'a o "5 'i-i P o «+:; J. 03 O^ g 'P boSP ^ a ® ^ P «>! I-I s o h3 O sp d ^.5 o3 O .P « ^ nd © o a ° O t>c © 3 m w T3 > P cS c8 op o3 c8 X ^ ^ .2 p P 2 '1 2 © P 3 o 8 M bc.a -2 M ■a. 8 T3 P! O rQ N O o O C5 bcr.1 T3 U O © ■ Sp 0 O bC T3 3 ,P a . bC ?rrb S3 bc:3 o >. P SP tn © CO ■^ > © tn © M © P > kT P 1 N — , O - P I* ^ OCOi9COF^O(NiPpt;'C^COQOt;'qiC^»0 OfH4ic»csiido'-Hidc35i-H4COTjH • - ■■-- W.I CDC000 0C(Mi00iO05CCI00Cli-HCM'^rt^G0r-ii-H i-HcoiOi-Hi-HTt<'<^iocoioio»o'sq>coTjH'>^ior^'-Hco>-0(M'^oo !> ce -O 1-3 C&S t;-i-HppF^CMppCO-^rHpppppppPip pCOl:;-CMpcO(Mpl:;-t;-pO idt^do'-^AcbcMkdt^idt^ciicoAobAoooococMOodAobi-Mcoiot^coiot^ 050i050505050iOiCiC5050505G5C3030000005030505050C5CiOC5C5C5 F— ^ F— H ►3 so.' O»0CDC0i0Oi0C0C0t-i0i:DO(MO001>.i— lOOpHOiOt-COiOCOCOOCOt^OOCOO '-i(MCOi-HCMCOO'-HCM'-iCMCO'-HCMCOCMCOTtlcOTtC^^OO'^c0--lCOI:-CDPll0Ol>^> CO»Ot^(MOODi-HCOiOCOiOt^CM'^CDiOr'OOlr-000'-HfO'<^iOCOC»i-HCOiOPlfOiO ooooooooooGOcx)ooGOooQOooc30ooooooooooooooc5 o :pS bC c ’S « ^ a IOJ0101010»0 1010»0 (M(M ipioio ppiO oooooooooooooooooocococoidididcocococsojo^oooooooooooo CMCO'^CMCO'rl^CMCOTtHCO'^lOCMCOTtH'^iOOOiOCOt-rHCMCOCMCO'^r-HtMCOCMCO-^ p uo o COCOCOOCOCOr-Hl— ll— il— li-HCOCOCO.-Hl— li-HCOOCOobobciOl— IrHl— (CDOCDi— Ir-Hf-H OI:^C5iOt^Oi'^OOOOGOO'^CDGOO:i-HCOOCMTtooiooooo>oioooocMC „ 4 „ .. . . 0-113 0-0250 ?? „ 7 „ .. .. 0-115 0-0275 5 ? „ 24 „ .. . . 0-126 0-0425 „ 48 „ .. . . 0-145 0-0830 The same flour, Aifiien extracted AAuth alcohol (rectified spirit) for 24 four hours, shoAA'cd after filtration the presence of 0-03 per cent, of acidity soluble therein. Flour does not give up the Avhole of its acidity immediately to either Avater or alcohol. Planchon, therefore, recommends instead the titration of the Avhole flour in the presence of Avater, and gives the folloAAing as the results of such tests, still reckoning total acidity as sulphuric acid : — 774 THE TECHNOLOGY OF BREAD-MAKING. Nine Roller Milled samples of fresh flour Stone Milled sample of fresh flour Second sample of do. Damaged flour unfit for use Second sample of do. Acidity per cent. from 0-105 to 0-122 .. 0-119 . . 0-133 . . 0-160 . . 0-565 The authors may state that they have for some time independently adopted the method of titration of the whole substance for both flour and bread testing, and confirm the conclusions arrived at by Planchon. The mode of titration of the mixed flour and water is performed in just the same way as with the filtered aqueous extract. 840. Analysis of Old Flours. — ^Balland and Planchon state that old flour which has reached |its extreme limit of possible preservation, and thereby lost its commercial value, is being rejuvenated by passing through the mill with a proportion of fresh flour. Such mixed flour escapes detec- tion by trade experts, and passes as genuine new flour. Very shortly, how- ever, the newness passes ofl, and the whole flour becomes stale. On exam- ination such flours are found to have both ash and water normal, but the fat will have decreased and the acidity increased. The gluten also shows signs of change, being less coherent, and having a tendency to produce frothiness in the water employed for washing it. This latter characteristic is specially noticeable in the case of the gluten being allowed to remain under water for 24 hours after being extracted. Fresh washing at the end of this period causes, in addition to frothing, much loss of weight. The following figures give the results of examination of three such samples of mixed flour compared with genuine new flours : — Sample No. 1 Original Gluten. Per cent. . . 29-6 Gluten re-washed after 24 hours in water. Per cent. 18-0 „ 2 . . 36-4 27-2 55 55 ^ . . 36-0 26-4 New Flour A . . 38-8 34-8 5 5 5 5 B . . 36-0 ■ 32-4 55 ,5 C . . 36-0 31-2 841. Separation and Identification of Acids of Sour Bread. — ^The acids occurring in either sour bread or dough may be divided into the two groups of fixed and volatile acids. The former consist almost entirely of lactic acid, while the latter may contain acetic or butyric acids. An approximate determination of the fixed and volatile acids may be made in the following manner : — Take 100 c.c. of the solution as directed to be prepared for determination of acidity, and evaporate to dryness in a platinum basin over a water bath, dilute again wdth pure distilled water, and repeat the process of evaporation. Titrate the residue vdth decinormal or centinormal acid, and calculate the acidity as lactic acid. Subtract the number of c.c. used for the titration from the total quantity required for the 100 c.c. of the soluble extract ; the difference is the amount of volatile acidity, and may be calculated as acetic acid. It is important to make this determination in a platinum vessel, as glass imparts sufficient alkalinity to the liquid to partly, if not entirely, vitiate the results. Another objection is that an aqueous extract of either flour or bread, as shown by Balland, does not give up the whole of its acidity to its filtered aqueous extract. It is difficult on the other hand to work on the whole flour, because on boiling vdth water the starch would gelatinise, and thus produce an unworkable mass. SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 775 The same method may be employed on bread, in whicli case take 10 grams of bread, and measure out 100 c.c. of water ; rub the bread into a paste in a mortar, witli a little of the water, and finally add the whole. Transfer to a flask, and add I c.c. of chloroform (having a neutral reaction to phenolphthalein), shake up vigorously, and allow to stand over night. In the morning, decant off the clear supernatant liquid, and filter. Take a measured quantity of the filtrate, and evaporate as before in a platinum basin ; calculating volatile and fixed acids respectively as acetic and lactic acid. A more accurate method of determining the volatile acids in bread is based on distillation in vacuo. For this purpose the following apparatus may be employed. Select a good round-bottom Bohemian flask of about 1 litre capacity, a, Fig. 115, fit to it a sound cork, through which three holes have been bored. Through one pass a tube, b, leading to the bottom of the flask, through another, the thermometer, c, registering to 200° C., and through the third, the leading tube, d. The thermometer must be so arranged that its bulb shall be about the middle of the flask. By 'means of a cork connect up d to the Liebig’s condenser, e, and attach the lower end of the condenser by means of tubing and corks to the bulbs, m n, the capacity of which should be about 250 c.c. Connect up the further bulb, m, by corks and tubing, o p, to a powerful water or mercury vacuum pump, preferably the former. Arrange the whole apparatus so that the flask, a, is fixed by means of a retort stand and clamp in the bath, q, which in its turn is carried on a small heating burner. Close the open end of the tube, b, by means of a piece of india-rubber tubing and pinch cock, and set the vacuum pump in motion. Wait until a vacuum is obtained ; stop the pump, and watch the vacuum gauge to see whether the apparatus is air-tight. A vertical spiral worm condenser may with advantage be sub- stituted for the Liebig’s condenser, e. Cut the bread to be tested into small dice, not more than three-eighths of an inch square ; weigh off 250 grams, and transfer to the flask, a, and replace the cork, taking care that the end of the tube, b, does not get choked. Close b with the pinch cock, pour sufficient distilled water into m ^ to seal the connecting tube at the bottom, and connect up the whole apparatus. 776 THE TECHNOLOGY OF BREAD-MAKING. Fill the bath, q, with glycerin to very nearly the top, and arrange a ther- mometer, r, to take the temperature of the bath. Set the vacuum pump going, and turn the water on to the condenser. Then light the burner, and raise the temperature of the glycerin bath to 150-160° C., and maintain it at that point. The moisture of the bread is volatilised, condensed in passing through the condenser, and collected in the bulbs, m n. The escape of glycerin vapour from the bath may be largely prevented by covering over the top with pieces of cardboard. When the distillation slackens, turn olf the pump ; admit air slowly through the tube, h, until the whole apparatus is filled, and then again exhaust. “ Wash the flask out with air in this way repeatedly. At the expiration of about 40 minutes, stop the pump, admit air through h, and disconnect the flask, a, from the condenser. Re- move from the bath, and shake up, so as to thoroughly mix the bread. Again, connect up the apparatus, and recommence the process of distilla- tion ; at intervals of about half an hour, repeat the operation of discon- necting the flask and shaking up the contents, doing this altogether three times. In about two hours from the commencement, the whole of the moisture will have come over, and the thermometer inside the flask will register about 125° C. Weigh the residual dry bread, and thus determine the percentage of moisture lost : measure also the total volume of distil- late. Determine acidity in the original bread, dry residue, and distillate, using for the two former, tests on the whole substance without filtration. As before, the volatile acidity may be calculated as acetic, and the fixed as lactic acid. 842. Duclaux’s Method of Estimating Volatile Acids. — ^Duclaux finds that of the volatile acids of the acetic series, each has its own definite rate of distillation under certain fixed conditions. Thus, if 110 c.c. of a mixture of acetic acid and water be taken and distilled in a 300 c.c. flask or retort until I f or 100 c.c. have distilled over, it will be found that the quantity of acid in the distillate is very nearly 80 per cent, of the whole, independently of the strength of the original solution of acid. Further, if the distillate be collected in successive fractions of 10 c.c., and each titrated separately, the proportion of acid passing over in these equal volumes will in all cases be the same for each successive volume provided the acid is pure, but will vary appreciably in the presence of even traces of the other fatty acids. Foreign matters other than acids do not seem to have any very great influence on the course of the distillation. The table on page 777 gives the percentage of acid which distils over in each successive 10 c.c. for acetic and butyric acid respectively. The columns A show the percentage of the total acid in the distillate which passes over with each fraction : while in columns B the percentages of the total acid in the whole liquid operated on are given. Taking acetic acid solution of whatever strength, 5-9 per cent, of the whole of the acid will come over in the first 10 c.c., 6-2 per cent, in the second, and so on. The quantity of acid, which comes over, gradually increases until in the tenth 10 c.c. 12-1 per cent, is found, making altogether 79-8 of the total acid, and leaving 20-2 per cent, in the remaining 10 c.c. in tlie flask. With butyric acid, on the other hand, although the boiling point is higher, the acid comes over more rapidly in the earlier part of the distillation. Tims, the first 10 c.c. contain 16-4 per cent, of the whole of tlie acid, the last 10 c.c. 3-5 per cent, of the whole, while only 2-5 per cent, remain behind in the 10 c.c. contained in the flask. When a mixture of acids is distilled, each maintains its own rate of distillation independently of tlie otliers. It is thus possible, by fractionally distilling a solution of volatile acid, not only to identify the acid, but also to estimate the propor- tion of each which is present in a mixture. To do this exactly a somewhat SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 777 Fractional Distillation of Acids — Luclaux. Acetic. Butyric. A. Per cent. B. Per cent. A. Per cent. B. Per cent. 1st. fraction of 10 c.c. . . 7-5 5-9 16-8 16-4 2nd, ,, 7-9 6-2 , 15-1 14-7 3rd. ,, 8-2 6-7 13-5 13-2 4th. ,, ,, 8-6 6-9 12-3 11-8 5th. ,, 9-1 7-3 10-2 10-1 6th. 9-6 7.6 9-3 9-1 7th. „ 10-2 8-2 7-8 7-6 8th. 11*5 9-2 j 64 6-3 9th. 124 9-8 1 5-0 4-8 10th. ,, ,, 15-1 12-1 ' 3-6 3-5 Total distillate = 100 c.c. 100-0 79-8 ! 100-0 97-5 Remaining in retort = 10 c.c. 20-2 2-5 complicated calculation is necessary, but when only the two acids, acetic and butyric, are present, the accompanying table, page 778, of rates of distillation of mixtures of the two in certain definite proportions, will serve as a guide in approximately estimating the quantity of each which is present. The accurate estimation of volatile acids in dough and bread is fraught with special difficulties, some of which have been already recounted. It is impossible to proceed by working down the dough into a thin “ cream with water, and subjecting that to distillation, because the starch would gelatinise and the resultant paste would boil over into the condenser. An aqueous extract may be made with chloroform water, but, as shown by Bal- land, a large proportion of the acid does not yield itself to the filtered ex- tract. (Out of 0T26 per cent. Balland found only 0-042 per cent., or exactly J, in a filtered solution after water and flour had stood together for 24 hours.) Further, when working with this solution, a portion of the lactic acid it contains distils over. Bread presents less difficulties than dough, because it can be more readily submitted to distillation in vacuo. The best method of estimating will be to obtain the distillate of two lots of 250 grams each of bread, and work on that, which will give altogether about 200 c.c. of distillate. Experiment shows that by this process none of the volatile acias is lost ; for on adding a second pair of bulbs between m n and the pump in Fig. 1 15, and placing 20 c.c. of centinormal soda in these, it was found by titration at the close of the experiment that none of the soda had been neutralised by acid passing over from m n. On the other hand, the distillate obtained in this manner apparently contains traces of lactic acid. In a special experiment 500 c.c. of distillate were taken, a little zinc oxide added, and evaporated down. The concentrated solution was filtered from excess of the oxide, and evaporation continued until about 1 c.c. only remained — on cooling crystals of zinc lactate separated out. These erystals were specially tested for acetic acid, and gave no reaction. Measure first the total quantity of distillate, and determine its acidity in 10 or 20 c.c. Then prior to starting on the estimation the following reagents are necessary ; — Prepare distilled water free from carbon dioxide and neutral to phenolphthalein, and with this make up some centinormal Distillation of Mixtures of Acetic {a) and Butyric Acid (&)— Duclaux. 778 THE TECHNOLOGY OF BREAD-MAKING ip CM p Ip q- q- p p p qi rci CO r-H co do CO rd id r--t II cd II >? p p cp qi qi p 1 < lO CM I-H 6 CP GO cd id 1 pH rH l—i .-I'M 00 CO rH qi p p p II m CM ,—1 o CP GO cd cd cd rH o 1 — 1 r-H p p p p p CP 1 II < CM cd A 6 CP do 1 1— H p Cp GO q- p p p II pq 6 o CP do GO td 6 r-H fH r— 1 cccc II 1 — 1 rH p p p p p p 1 -’i CM CM o o o GO GO cd GO 1 !£ ^.C5 1 — 1 pH i-H o CO p p p p P p I-H CM pq o OP GO GO do GO GO CP rjH II r— H II CO t;- p p qi qi p p 1 n-H c5 O CP CP CP o CP CP cd rH rH CM p p p t;- p p p p p ■^1— II pq do GO GO GO GO CP CP cd 1— H 1 1 el-o op t;- p cp p p p p I < CP' OP CP CP CP CP o o 6 di 1 1— H f-H 1 1 qp p p p p p qi p f— H p p II pq CO CP GO CP 6 cd c'x -f-ix X:^ ip p cp p p qt p p I 1 II < OP CP CP CP CP CP CP 6 6 di 1 1 e '-O rH o CM p p p qi p p 1— 1 cp ^ 1 pq GO GO CP cd I— 1 I-H II o op p p cp cp p q- p p 1 c l-a -li GO GO GO CP CP CP 6 6 A cd 1 r— i 1— H 'f p p cp p p p p p p II pq CO CO CO GO GO 6 r-H CP i-H qp p p p p p cp p 1 II -li GO GO GO CP CP O O 4^ 1 rH e ^ ■5f c CM CO ic o GO CP o I-H I— 1 No. 11 is the 10 c.c. remaitiingjn the retort after the distillation. SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 779 sulphuric acid and soda. Titrate these against each other — they must exactly agree. Test a clean glass Wurtz flask for alkalinity by boiling 110 c.c. of pure distilled water down to 10 c.c. in it, and titrating the residue — this should still be neutral to phenolphthalein. If the flask gives an alka- line reaction, it must be discarded. The authors find flasks of “Jena ” toughened glass very free from alkalinity, and so specially adapted for this work. Working with such dilute solutions, the loss through imperfect conden- sation is sufficient to materially affect results, particularly when the rate of distillation is irregular through bumping. The following arrangement of apparatus. Fig. 116, is recommended for the distillation: a is the side- tube (Wurtz) flask of 300 c.c. capacity, attached to the condenser, h. (For this a spiral condenser may be substituted witli advantage. ) Pro cure some colourless glass tubes, c, about 3 inches high and 1 inch diameter, and graduated with a 10 c.c. mark, as shown. Fit up three of these with corks and leading tubes, cl, and bulbs, e f (like small nitrogen bulbs). To commence the experi- ment, place 5 c.c. of cen- tinormal soda in the bulbs, e /, and connect up the apparatus. Turn on the water through the condenser, and start the distillation. Meantime get another tube, c, with its bulbs charged with soda in readiness. Watch till 10 c.c. have come over, and replace the filled c tube with the empty one. Transfer the contents of both tube and bulbs to a beaker, rinsing out with a little pure distilled water, and immediately titrate with centinormal soda or acid, according to whether the solution be acid or alkaline. If acid, 5 c.c. -f quantity taken for titration = the acidity. If alkaline, 5 c.c. — quantity for titra- tion = acidity of the distillate. Remove the second distillate, and replace by another receiver, c, and charged bulbs. Titrate each in precisely the same manner, and continue until the ten distillates have been collected. Finally, titrate the 10 c.c. which remain in the flask. The arrangement of receivers fitted with charged bulbs appears complicated ; but a number of experiments have shown that with open condensation there is a very con- siderable loss of acid. Having obtained by titration the amount of acid reckoned as centinormal in each fraction, calculate out what percentage of the whole acid in the 110 c.c. it represents in each case : in fact, work out column B as per table for the particular experiment. In order to explain this calculation, let us assume the following to be the results of an analysis' : — Bread taken . . . . . . 500 grams. Weight of Dried Bread . . 324 ,, = 64*8 per cent. Volume of distillate . . . . 180 c.c. Acidity of 10 c.c. — 12T c.c. A/lOO acid = 217-8 on total distillate. Took for fractional distillation, ! 10 c.c. = 133-1 acidity. Fig. 116 . — Appakatus for Duclaux Distillations. 780 THE TECHNOLOGY OF BREAD-MAKING. 1st. fraction 2nd. „ 3rd. ., 4th. „ 5th. „ 6th. 7th. ,, 8th. „ 9th. „ 10th. ,, 11th. residuum Acidity Observed Acidity in c.c. N /lOO acid. 9-4 calculated in percentages of total in 110 c.c. 7-0 9-6 7-2 9-7 7-2 9-8 74 10-0 - 7-5 10-5 7-8 10-9 8-2 11-6 8-8 12-7 9-5 14-8 11-1 24-1 18-1 The figures in the second column are simply calculated in percentages 9-4 X 100 ^ , 1331 = ' Turning next to the table (page 778) of distillation of mixtures of acetic and butyric acids, we find that these figures closely agree with those yielded by ten parts of acetie to one of butyrie acid : consequently the assump- tion is that the volatile acids exist in these proportions to each other. Of 917, Q y 1(1 the total acidity, therefore = 198 c.c. N/lOO aeid are due to acetic acid, and 217-8 11 = 19-8 c.c. A/100 acid to butyric acid. The factors for A/100 acetic and butyric acids respectively are 0-0006 and 0-00088 ; and as 500 grams of bread were taken, Ave have 198 x 0-0006 x 0-2 = 0-023 per cent, of acetic acid, and 19-8 x 0-00088 x 0-2 = 0-003 per cent, of butyrie acid. This example, Avith hypothetical quantities, is simply given as an illus- tration of the mode of ealeulation. 843. Estimation of Proteins. — ^For technieal purposes,- proteins are noAv determined by AAliat is knoAAm, after the name of the inventor, as Kjeldalihs process, (or some modification thereof). This method depends on the fact that, Avhen an organic substance is heated AA'ith a mixture of concen- trated sulphurie acid and potassium sulphate, its nitrogen, if any, is (Avith A^ery feAV exeeptions) converted into ammonia, and retained by the aeid as ammonium sulphate. The residuum is subsequently rendered alkaline by excess of soda, and distilled. The ammonia comes over and is collected in a knoAAm volume of deeinormal aeid, Avliich is titrated, and then the amount of ammonia 'determined. From this the percentage of protein matter is readily calculated. A detailed description folio aa^s of the mode of performing an organie nitrogen estimation by Kjeldahl’s method. Reagents and solutions required . — Pure eoncentrated sulphurie acid, as free as possible from nitrogen compounds. Concentrated solution of caustic soda. Take 3 lbs. of commereial sodium liydroxide, either in poAA^der or sticks, and dissolve in as small a quantity of Avater as possible ; let the solution eool, and make up to suffieient to fill a Wineliester quart (about tAVO Imperial quarts). Store in a Winchester fitted Avith india-rubber stopper. PoAvdered potassium sulphate. Heat this for some time in an iron A^essel, and store in a stoppered bottle. Deeinormal sulphuric acid and sodium hydroxide. Methyl orange solution. Apparatus . — Speeial long-neeked heating flasks of Jena toughened glass, SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 781 of 300 or 500 c.c. capacity. Wrought-iron stand to hold four of tliese flasks for heating purposes. This stand should consist of a stout sheet iron plate, 15 inches long by 4 J inches wide, supported on four legs for ordinary bunsen burners, and with four holes, each 2 inches diameter, through the plate. On the one long edge of the plate an upright back should be fixed about 4 inches high, and with round notches cut out so that when the flasks are resting in the holes in the plate, the necks may lie in the notches in the back. The flasks are thus supported when in use in an oblique position. Distilling Apparatus . — If 500 c.c. flasks are used, these may be employed direct for the distillation. If not, a 500 c.c. flask of the same kind should be used for this operation. To this flask, a, in Fig. 117, fit a rubber cork and splash-head, b. This latter is attached in turn to a condenser, c, fitted with a condensing tube of pure tin. The lower end of the condenser, d, is passed through a rubber cork, and thus fixed to the Kjeldahl bulbs, e /. Mode of Analysis . — To estimate total proteins on flours or meals, weigh off 1 gram of the sample and transfer it to a clean, dry, heating flask. The weighing is best done with a pair of counterpoised horn dishes for the bal- ance. Obtain a wide- mouthed glass funnel that will just fit the flask, and pour into it the flour or meal, carefully brushing every particle in by means of a brush kept for the purpose. Or if preferred, make a V-shaped gutter out of glazed paper that will pass right into the neck of the flask and down 782 THE TECHNOLOGY OF BREAH-MAKING. into the bulb, and introduce the substance by means of this. In any case all particles must be brushed right down into the flask. By means of a pipette add 20 c.c. of the concentrated sulphuric acid and about 10 grams of the potassium sulphate. This latter may be conveniently measured, using for that purpose the end of a test tube, or what answers very well, a sewing thimble of the right size. (This may be obtained once for all by weighing out the quantity.) Rinse the acid gently round inside the flask so as to thoroughly wet it, taking care that there are no dry patches of flour between the acid and the flask. Occasionally one gets a small patch which obstinately refuses to mix with the acid, which must then be provided for in the heating. Arrange the flask stand in a stink cupboard designed so as to carry ofl the fumes produced, and stand the flask obliquely in one of the holes, with its neck lying in the notch. Should there be any adherent dry patches of flour, turn the flask so that they are out of the liquid and on the upper side of the flask. Turn on a very small bunsen flame ; as the acid gets hot it carbonises the flour, which froths up and gradually subsides into a tarry looking liquid. The steam of the boiling acid attacks any flour patches on the upper part of the flask, and speedily brings them down into the solution. Continue to apply heat so that the acid is just below the point of ebullition, a bubble of steam escaping only occasionally : the black liquid gradually loses its colour, and in about 45 minutes has usually become colourless. As soon as this stage is reached it is allowed to cool. When perfectly cold the next step is to arrange for the distillation ; this, however, must be preceded by a blank experiment, made in order to deter- mine the amount of ammonia present as impurity in the reagents used. Add 20 c.c. of the concentrated sulphuric acid to the contents of the 10 gram measure of potassium sulphate in a round-bottomed flask precisely as before : heat so as to melt the sulphate, and allow to cool. Measure off 200 c.c. of water in a graduated jar, and pour it into the flask containing the acid and sulphate — the liquid becomes very hot, but does not spurt if sufficient water is added. Next add a drop of methyl orange, and give the flask a shake round so as to mix the contents. Then by means of a funnel pour some of the strong soda solution from a 100 c.c. graduated measure into the flask until the acid is neutralised, and add an extra 5 c.c. Make a note on the label of the bottle of the total quantity thus used. (The object of adding methyl orange is to determine once for all how much soda is neces- sary ; this quantity is then used in the estimations until a fresh quantity is made up, when it should be again titrated.) Introduce a few fragments of coarsely granulated zinc in order to prevent bumping, and cork up the flask to the splash-head, h. By means of a pipette, introduce 25 c.c. of decinormal sulphuric acid into the bulbs, e /, and connect to the condenser. Turn a current of cold water through the condenser, and light a bunsen underneath the flask ; its contents speedily come to the boil, and the steam and ammonia together are condensed, and retained in the Kjeldahl bulbs, m n. Continue the distillation until about 200 c.c. have come over ; turn out the lights, disconnect the bulbs, and pour their contents into an evaporat- ing basin, and titrate with decinormal soda and methyl orange. In the blank experiment, the quantity of ammonia eyolved amounts usually from 0-3 to 0-5 c.c. of decinormal ammonia : make a note of this quantity, and repeat the blank with each new lot of concentrated acid and soda. So far as possible make these up each time in about equivalent quantities. Returning to the clear solution obtained by treatment of the flour or meal witli acid and sulphate as previously described, if a 500 c.c. flask has been used, add water to it in the same way as to the blank, and then the quantity of strong soda solution as ascertained, then the granulated zinc and distil as before. If the burning down with acid and sulphate has been SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 783 carried out in a 300 c.c. flask, the eold eontents must first have 150 e.c. of water added to them, and then be transferred to a 500 c.c. flask. Witli the remaining 50 c.c. of water give the 300 c.c. flask several rinsings, whieh must be added to the main portion in the larger flask, after which the requisite quantity of soda is poured in. As soon as the soda is added, the ammonia is set free and therefore no time should be lost in corking the flask to the splash-head in order to prevent any escape. At the close of the experiment thoroughly wash out the distillation flask, and place it bottom upwards in a rack so as to drain. Preserve the washed zinc in a small bottle or flask of water for use in the next test. Calculation . — As 25 c.c. of acid are taken for the determination in the bulbs, that quantity, less the amount required for its titration, represents the amount of decinormal ammonia evolved, thus : — 25 c.c. - 13-3 c.c. A/10 soda = 11-7 c.c. A/10 NH 3 . (According to blank experiment, the correction is 0*4 c.c.) then 11-7 — 0-4 = 11-3 c.c. from nitrogen of flour. As 1 c.c. of A/10 NH 3 equals 0’0014 of nitrogen as ammonia, then 11*3 X 0-0014 = 0-01582 of nitrogen. Osborne and Voorhees And that gliadin contains 17-66 per cent, of nitrogen, and glutenin 17-49 per cent. As these two proteins constitute the main portion of the proteins of flour, they assume wheat proteins to contain 17-60 per cent, of nitrogen. As 5-68, they multiply the quantity of nitrogen found by 5-68, as a constant factor in order to convert the percentage of nitrogen into that of proteins. Proteins as commonly separ- ated eontain a quantity of water of hydration which is not driven off at 100 ° C., and therefore multiplication by 5-68 does not give the quantity of hydrated proteins. The flgure formerly employed for calculation of nitrogen into hydrated proteins was 6-33, but this is now regarded as being more eorrectly expressed by 6-25. As this last factor, 6-25, has been very ex- tensively employed, it is still most commonly used so as to make results comparable with those already on record. In returning analytic results, the actual quantity of nitrogen found, and also the factor used for calcula- tion into proteins, should be stated. Returning to the 0-01582 gram of nitrogen obtained in the experiment, then 0-01582 X 5-68 = 0-0898 gram of true proteins. 0-01582 X 6-25 = 0-0989 gram of hydrated proteins. These are the quantities in 1 gram of flour, and therefore these quantities X 100 = 8-98 per cent, of true proteins, and 9-89 per cent, of hydrated proteins respectively. As 0-0014 and 5-68, and 6-25, respectively are constants, their respective products, 0-00795 and 0-00875, may be used as factors. Therefore the number of c.c. of decinormal acid neutralised by the evolved ammonia xO-00795 gives the weight of true proteins, and x 0-00875 gives the weight of hydrated proteins, in the quantity taken for analysis. 844. True Gluten Estimation. — ^For jthis purpose take about 0.15 gram of dry gluten, weigh it accurately, and treat with acid and sulphate as with the whole flour. Conduct the whole estimation precisely as before ; then, number of c.c. of NH3 evolved x 0-00875 = weight of true gluten (hydrated proteins) in the quantity of dry gluten taken. The following data show the mode of calculation : — Flour yields 13-10 per cent, of dry crude gluten. Taken for true gluten estimation — 0-152 gram. 784 THE TECHNOLOGY OF BREAD-MAKING. Ammonia evolved, less correction, 14-6 c.c. 14-6 X 0*00875 = 0*12775 gram true gluten. As the whole flour contained 13*10 per cent, of true gluten, then : As 0*152 : 13*10 : : 0*12775 = 11*01 per cent, of true gluten. Therefore : Percentage of crude gluten x true gluten found in estimation Crude gluten used for estimation ~ percentage of true gluten in whole flour. In order to test the “ True Gluten ” determinations the folio vdng experiment was made : — Four glutens were extracted from the same flour, one being washed, as well as could be judged, to the right degree of purity ; two of the others were purposely underwashed, and the fourth overwashed. The following were the results in wet and dry glutens : — No. 1. Washed correctly . . No. 2. Insufflciently washed No. 3. Would pass for being washed sufficiently No. 4. Lost weight beyond No. 1 with very great difficulty Wet Gluten. 53*0 per cent. 63-0 56-7 48-5 Dry Gluten. 16*1 percent. 20-0 16-8 15-1 True Gluten. 15*0 per cent. 15*1 15-1 14-7 „ Note No. 4 was weighed when at 51 per cent., and again washed in clean water ; this water on testing gave starch colouration with iodine solu- tion, showing that even at 51 per cent, starch was still present. Notwith- standing the wide differences in crude gluten between Nos. 1, 2, and 3, the true gluten is practically identical in all. In No. 4, however, the protein itself is being lost. This was an exceptionally tough, hard, glutenous flour, or doubtless there would have been an appreciable difference in true gluten between Nos. 1 and 2. In true gluten estimations it is recommended that where the true gluten does not amount to 80 per cent, of the crude gluten, another estimation be made of the crude gluten and the first one rejected. 845. Modification of Process for Estimation of True Proteins only.— The determination of proteins by the Kjeldahl process is open to the objec- tion that other nitrogenous products which existed in the grain or flour are also reckoned as nitrogen from proteins. It is at times of service to estimate the percentage of nitrogen existing as proteins or flesh formers, as distinguished from other compounds of nitrogen. Carbolic acid possesses the property of coagulating the soluble pro- teins, and thus rendering their separation from nitrates, etc., comparatively easy. Take one gram of the flour or meal and cover it in a beaker with a warm 4 per cent, alcoholic solution of carbolic acid : this may be pre- pared by taking 4 grams of the pure acid, and adding thereto sufficient alcohol (re-distilled methylated spirits) to make up the volume of 100 c.c. Let tliis stand for a quarter of an hour, then add a little boiling aqueous 4 per cent, solution of carbolic acid, stirring the mixture for about a minute, and then allowing it to cool. Wash the solid residue several times })y decantation with the cold aqueous carbolic acid solution, pouring the washings on to a small Alter, and finally transfer to it the residue itself ; thoroughly dry tlie filter and residue. Make a Kjeldahl estimation on both the residue and filter, cutting the latter up into shreds, and treating both with the acid and sulphate in the usual manner. The percentage of nitrogen SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 7S5 thus obtained, multiplied by 6-25, gives the quantity of true hydrated proteins. 846. Estimation of Soluble Proteins. — ^To make this estimation, take 50 c.c. of the filtered solution as prepared for soluble extract, and evaporate to dryness in one of the acid flasks. For this purpose the flask should be placed in the hot-water oven, as, unless the whole flask is kept hot, recon- densation occurs. Even in the hot-water oven evaporation proceeds but slowly ; it may be considerably hastened by immersing the flask in a bath composed of water with a large excess of potassium carbonate. This easily maintains a temperature of 110-115° C. Treat the dry residue in the flask with acid and sulphate, and proceed in the usual manner. It should be remembered that 50 c.c. contain the soluble proteins of 5 grams of the flour. 847. Gliadin Estimations; Classification of Methods. — ^Serious objec- tions have been taken to gluten estimations on the ground that they cannot afford a true determination of the total protein content of the flour ; and therefore it is urged that they should be dispensed with and instead a deter- mination made of the nitrogen of the flour and the percentage of protein ob- tained by calculation. Most of the investigations on this matter have been conducted with reference to the strength of flour, and accordingly the various researches and conclusions based thereon have been fully described in Chapter XV. dealing with that subject. That chapter should be carefully read as an introduction to the whole question of gliadin determinations. In particular, the results and conclusions of Norton and Chamberlain, paragraphs 450 and 452, should be studied in connection with the point just raised. If gluten determinations cannot yield a true indication of the protein content of flour,, it follows that the protein content cannot yield a true indication of the gluten content of the flour. From what has preceded, it will be seen that the authors regard that agglomerate of various flour constituents, which is called gluten, as being the factor which in virtue of its quantity and quality largely dominates the properties of a flour. That body can be de- termined with considerable accuracy by a simple physical operation, and possesses well-marked physical characteristics. They therefore attach importance to its estimation. It being known that gluten is largely com- posed of glutenin and gliadin, and that these bodies may roughly be compared to the sand and lime in a sample of mortar, one being the component which gives substance and the other the constituent which acts as a binding agent, it would seem that the relative proportions of each must exert a considerable effect on the qualities of gluten. Accordingly, the effect of such relative proportions has received most careful examination. Certain earlier observers, as for example Guthrie and Fleurent, attached considerable importance to the proportions of each, and have suggested the bearing which they have on the character of flour. Others, among whom are included Snyder and Wood, have arrived at the conclusion that flours cannot be differentiated in quality according to the proportions of gliadin and glutenin. Thus Snyder finds that gliadin may range from 45 to 70 per cent, of the total protein, without the flour being affected in any but a minor degree. Almost every one of those who have investigated the problem has adopted a different method of determination, and therefore no very direct comparisons can be made. Further, from time to time, each operator has modified his own methods as possible improvements have suggested themselves. The methods adopted divide themselves into (1) direct estimations on the flour, and (2) estimations made on the washed out gluten. Each of these merits some little examination in detail. .3 E 786 THE TECHNOLOGY OF BREAD-MAKING. 848. Gliadin Estimations on Flour. — ^On treating flour with 70 per cent, alcohol, the gliadin, together with some portion of the water-soluble pro- teins, as well as the soluble carbohydrates and soluble ash, is dissolved out. It is therefore not possible to estimate gliadin by direct w'eighing of the residue from the evaporated filtered solution, but instead, recourse must be had to a nitrogen determination on the filtrate by the Kjeldahl process. Chamberlain has carefully investigated the extraction of gliadin, paragraph 452, and recommends that the estimation be made in the following manner : — Cold 70 per cent, alcohol should be used directly on the air-dry flour, and 100 c.c. of the solvent should be taken to either 2 or 4 grams of the flour, the extraction being continued for 24 hours with frequent or continuous shaking. These suggestions are now apparently adopted by most American chemists, thus Teller finds the most convenient means of determining the gliadin in wheat flours to be as follows : — ‘‘ Two grams of the flour are put in a flask of about 150 c.c. capacity, 100 c.c. of dilute alcohol, specific gravity 0-90, are then added to the flour, care being taken to mix the flour well with a small quantity of the alcohol before the entire amount is added. The flask is then set aside at room temperature for 24 hours, shaking occasionally to assure thorough extraction of the gliadin. The liquid is then filtered and 50 c.c. of the clear filtrate taken for determina- tion of nitrogen. The alcohol should be evaporated off on the steam bath before the sulphuric acid is added to avoid charring of the alcohol. The nitrogen obtained is then multiplied by the factor 5-7, or, as we find it more convenient in our laboratories here, the number of c.c. of decinormal acid obtained for each gram of flour is multiplied by the factor 0-8. This gives the per cent, of gluten or gliadin direct. In our commercial work here we determine the gluten by the Kjeldahl method, using 1 gram of flour and multiplying the titration of ammonia obtained by the factor 0-8 as given above. We find this to give as nearly the true amount of gluten in the flour as can be done by the most careful hand washing, and it is much more reliable when the work is done by different operators on different days.” [Personal communication, May, 1910.) In a paper, previously quoted. Teller has shown that alcohol of 0-90 specific gravity, i.e., 57 per cent, strength, dissolves more nitrogenous matter from flour than does 70 per cent, spirit. This points to the fact that the dilute alcohol takes up some of the water-soluble proteins in addi- tion to gliadin proper. Chamberlain also states that hot alcohol dissolves out less protein than does cold, and therefore recommends the latter. This again is an indication that other protein than gliadin is being dissolved, since gliadin is more readily dissolved on the application of heat than in the cold : on the other hand proteins of the albumin type become less soluble because of coagulation. It is important also to consider the bearing of the length of time of extraction in view of the nature of the solvent, a dilute solution of alcohol not being capable of inhibiting proteolytic action. Air- dried gliadin is “ very soluble ” in 70 per cent, alcohol, and must be at least equally soluble in the finely divided condition in which it naturally occurs in flour. With the use of a very large excess of the solvent, it would seem that the increase of protein dissolved by greatly prolonged extraction is not merely gliadin, but contains in addition alcohol soluble protein produced by proteolytic action on protein matter, which at the outset is insoluble in the dilute alcohol. Corroboration of this is afforded by the fact that when dough is allowed to stand under conditions which favour proteolytic action, there is a marked increase in the quantity of dilute alcohol soluble l^rotein. The method employed must be regarded as a measure of the amount of protein dissolved in dilute alcohol under certain definite con- ditions, but evidently is not a measure of gliadin only. Another point SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 787 which has to be considered is that according to Chamberlain, of the total gliadin and glutenin contained in the wheat and flour, only about 85 per cent, can be obtained as gluten by the washing process. On this the question arises whether this balance of 15 per cent, is a loss due to inherent faultiness of the gluten washing process, or whether it is the result of some of the gliadin and glutenin being in a non-adhesive condition and therefore not function- ing as gluten. This matter has been already discussed (see paragraph 469), and if the authors’ view be correct, then flour contains some gliadin which would be determined as such in a direct estimation on the flour, and yet is not contributing to its strength. The method adopted by the authors is substantially the same as that of Teller, except that, following more closely on the lines of Chamberlain, they use hot 70 per cent, alcohol, and take 400 c.c. to 4 grams of flour, (a quantity which may be somewhat in excess of that absolutely necessary.) They shake frequently during the 24 hours, or preferably shake con- tinuously in a shaking machine, a description of which is subsequently given in paragraph 854. After filtration, 200 c.c. of the clear filtrate are placed in a 500 c.c. long necked Jena flask. This is immersed in a bath of potassium carbonate and water, and connected to a spiral condenser. The alcohol is distilled off, and then the flask is disconnected and the heating continued until the solution is evaporated to dryness. This takes place rapidly with the bath at 110-115° C. The Kjeldahl determination is then made on the residue, and the results calculated in the usual way. 849. Gliadin Estimations on Wet Gluten. — The foregoing considerations have caused the authors to incline to determinations made on the wet gluten itself as being more likely to have a direct bearing on the problem of the quality of gluten and its effect on the strength of flour. In gluten- washing those bodies which do not go to the building up of that india-rubber like body are eliminated. The soluble carbohydrates and ash have been more or less removed, and also such soluble proteins as are not retained by the absorptive power of the gluten proteins. If therefore the alcohol solvent be applied to this body it can only extract what is practically soluble protein and the small amount of mineral bodies which is inherently associated with this substance. From its physical nature, gluten is a difficult body to treat with a sol- vent. Guthrie extracted the wet gluten with successive small quantities of 70 per cent, alcohol, the operation extending over four and a half days. He thus obtained from 22 to 41 per cent, of the gluten proteins as gliadin. There is always the uncertainty that in so long a time some of the gluten which at first was insoluble in dilute alcohol becomes soluble by a process of degradation due to proteolytic enzymes. For this reason some quicken- ing of the dissolving operation is eminently desirable. Fleurent adopted another method and dissolved the whole of the gluten in alcoholic potash solution, and then converted the hydroxide into car- bonate by passing carbon dioxide gas through the solution, thus re-precipi- tating the glutenin and leaving gliadin in solution. As potassium carbonate is somewhat soluble in 70 per cent, alcohol, there was still an active glutenin solvent present, and therefore it might well be expected that the whole of the glutenin would not be re -precipitated. By this process he obtained from the best flours about 75 per cent, of the gluten proteins as gliadin, an amount which is much in excess of the usual estimate. 850. Gliadin Estimations by Calcium Carbonate. — ^The authors devised and adopted a method which was intended to avoid the difficulties associated with both Guthrie’s and Fleurent’s processes, of which the following is an outline. Twenty grams of flour were washed for gluten, and the wet gluten 788 THE TECHNOLOGY OF BREAD-MAKING. weighed. This was divided into two equal parts, one of which was dried and weighed, and a portion used for the determination of true gluten. The remaining moiety was placed in a mortar and 20 grams of washed and dried precipitated chalk (calcium carbonate) added. (This chalk was washed until it gave no alkaline reaction to the washing water after filtration.) One hundred c.c. of 70 per cent, alcohol were measured off, and about 6 c.c. poured into the mortar. This mixture was then thoroughly triturated with the pestle, and more alcohol added as required until it had been ground down into a perfectly uniform slack dough. The whole of the gluten was thus perfectly comminuted. This was done with the greatest care. The piece of dough was then transferred to a flask, the remainder of the alcohol added, and the whole vigorously shaken. The dough was thus broken down into an impalpable powder, which was examined through the glass of the flask to see that no perceptible particles of gluten were present. (At first, some such particles were occasionally detected and the test rejected ; but after a little experience this never happened.) The flask was next immersed in hot water, and the alcohol brought quickly to the boiling point. As soon as this was reached, the flask was corked and shaken. The shaking was repeated several times while the mixture was warm. It was then allowed to stand over night at room temperature. In the morning, there was usually a slight deposit of protein matter on the sides of the flask, which was assumed to consist of glutenin that had been dissolved by the hot alcohol and re-deposited as it cooled. The conditions of treatment were such as should lead to the perfect solution of the very soluble gliadin in the solvent, while there was comparatively a very short time during which any actual change in the gluten could take place. With the gluten so finely divided, it was all immediately subjected to the action of the alcohol, and the tem- perature having been raised to about 70° C., enzymes must have been prac- tically destroyed. On first employing this process the alcohol solution was immediately filtered hot, and the gliadin obtained by evaporating 50 c.c. of the filtrate and drying and weighing the residue. In this way about 50 to 60 per cent, of the gluten proteins were obtained as gliadin. After- ward the solution was allowed to cool as described, with the result that much less gliadin was obtained. 851. Further Investigation of Trituration Methods. — ^For the purposes of this work, the authors have recently re-investigated the method, being guided in so doing by Chamberlain's conclusions on extraction of gliadin from flour. The following experiments were made. Sixty grams were taken of millennium flour, made into a dough with 40 c.c. of water, and the gluten carefully washed out at tlie end of an hour. The wet gluten weighed 21-426 grams = 35-71 per cent. A portion, 3 grams, was dried and weighed; it was thus found that the dry gluten amounted to 12-22 per cent, of the whole flour. The 70 per cent, alcohol was tested and found to leave on evaporation 0-002 gram per 100 c.c. Portions of 2 grams each were at once weighed off, as soon as the whole mass of wet gluten had been weighed, and were treated as follows : — No. 1. Ground up with 20 grams of chalk, and 500 c.c. of cold alcohol, shaken frequently and filtered at the end of 2 hours ; 250 c.c. evaporated for gliadin, dried and weighed. No. 2. Taken, 20 grams of chalk, 100 c.c. of alcohol, shaken frequently and filtered at the end of 24 hours ; 50 c.c. evaporated for gliadin. No. 3. Twenty grams of chalk, 200 c.c. of alcohol, shaken as before and filtered at 24 hours ; 100 c.c. evaporated for gliadin. SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 789 No. 4. Twenty grams of chalk, 300 c.c. of alcohol, treated for 24 hours ; 150 c.c. of filtrate evaporated for gliadin. No. 5. Twenty grains of chalk, 400 c.c. of alcohol, treated for 24 hours ; 200 c.c. of filtrate evaporated for gliadin. No. 6. Twenty grams of chalk, 500 c.c. of alcohol, treated for 24 hours ; 250 c.c. of filtrate evaporated for gliadin. No. 7. Ten grams of thoroughly washed and dried kieselguhr, 500 c.c. of alcohol, treated for 24 hours ; 250 c.c. of filtrate eva- porated for gliadin. As kieselguhr is more bulky than chalk a less volume of it was deemed sufficient. Blank tests were made both with the chalk and the kieselguhr, and the weight of residue deducted as a correction from that found with the tests on gluten. The following were the quantities of gliadin thus obtained : — No. 1. 1*89 per cent, of the whole flour. 2. D68 ., 3. 214 „ 4. 2-21 „ 5. 2-21 „ 6. 2-68 „ 7. 3-29 The quantities of 200, 300 and 400 c.c. yielded practically the same amounts with chalk, while more was obtained with 500 c.c. With kiesel- guhr, -the amount was considerably higher. Some more wet gluten was prepared from the same flour, and portions of 2 grams each were subjected to the following further tests. Some kiesel- guhr was broken down in water, and poured through a fine sieve in order to remove all lumps, then allowed to settle and the fine kieselguhr, in a state of suspension, decanted off from the sandy sediment. The kieselguhr was repeatedly washed with water, and then several times with 90 per cent, alcohol, and dried. As thus obtained it is a very bulky powder : — No. 8. Ground up the gluten in mortar with successive small quan- tities of cold alcohol, and liquid transferred to flask, using altogether 400 c.c. This operation lasted 48 hours ; then filtered, evaporated 200 c.c. for gliadin, dried and weighed. No. 9. Cut gluten into small pieces, boiled with about 25 c.c. of alcohol, then ground up in mortar as before, using altogether 400 c.c. Time, 48 hours. Filtered, evaporated 200 c.c. for gliadin. No. 10. Three grams specially prepared kieselguhr, 400 c.c. of cold alcohol, treated for 24 hours ; 200 c.c. evaporated for gliadin. No. 11. Three grams kieselguhr, 400 c.c. of alcohol, raised to boiling point, shook repeatedly for 24 hours ; evaporated 200 c.c. for gliadin. No. 12. Blank with 3 grams of kieselguhr, and 400 c.c. of alcohol, treated for 24 hours, and evaporated 200 c.c. of filtrate. The blank gave a residue of 0-004 gram, which was deducted from the weight of gliadin in Nos. 10 and 11. The following quantities of gliadin were obtained : — No. 8. 5-99 per cent, of the whole flour. 5, 9. 4-21 ,, ,, ,, „ 10. 4-07 ,,11. 4-/1 ,, ,, ,, Under these conditions, cold alcohol, only, extracted more than the hot ; while when kieselguhr also was employed more gliadin was obtained as a result of heating. ? ? ? ? ? ? ?? J? ?5 ?? ?? ?? ?? ?? ?? 55 55 55 790 THE TECHNOLOGY OF BREAD-MAKING. Adsorptive Properties of Re-agents . — By adsorption ” is here meant the removal of a body from its solution, by the adherence of its particles to those of some solid substance which has been introduced. Experiments were next made in order to determine whether the filter papers or the kieselguhr exercised any adsorptive effect on the gliadin in solution. Twenty grams of wet gluten from the same flour were ground up with successive small quantities of spirit, the operation lasting about 16 hours, and altogether 378 c.c. of filtrate were obtained. This volume does not represent the whole of the alcohol used, since a portion, together with some gliadin, remained on the filter. On this, the following tests were made : — a. 100 c.c. evaporated, weight of dry residue, 0-515 gram. h. 100 c.c. mixed with 3 grams special kieselguhr, allowed to stand 24 hours and filtered, 70 c.c. of filtrate evaporated, weight of dry residue, 0-272 = 0-389 in 100 c.c. c. 100 c.c. mixed with 7 grams of starch from same flour. (The starch was washed first with water, and then several times with 90 per cent, alcohol, and dried at about 60° C.) Gliadin solution allowed to stand 24 hours and filtered, 85-5 c.c. of filtrate evaporated, weight of dry residue, 0-440 =0-514 gram in 100 c.c. d. 78 c.c. re-filtered through a fresh dry paper, 74-5 c.c. of filtrate eva- porated, weight of dry residue, 0-380 = 0-510 in 100 c.c. The kieselguhr exerts a very considerable adsorptive action, about 24 per cent, of the gliadin present in the solution being retained in the kiesel- guhr. Wheat starch, on the other hand, is absolutely free from any such adsorptive power. The filter paper also is without action. As kieselguhr extracts more gliadin from gluten than does chalk, no tests were made on the adsorptive power of the latter, which in the quantity used would pre- sumably retain yet more gliadin. The residual gluten from the treated 20 grams was yet again subjected to further treatment with more alcohol, extending over another 24 hours ; this removed yet more gliadin, the amounts of dry gliadin being : — From 1st. extraction .. .. .. .. 1-9467 grams. „ 2nd. „ 0-3590 Total 2-3057 Twenty grams of wet gluten (about 6-6 grams of dry gluten), had there- fore yielded 2-306 grams of gliadin. The residual wet glutenin weighed 10 grams ; a portion of this was treated as subsequently described. No. 16. 852. Solution and Re-precipitation Methods. — ^Experiments were next made in the direction of dissolving the whole of the gluten in weak alcoholic soda solution, then re-precipitating the glutenin, and determining the gliadin in the filtrate. No. 13. For the first test, 1-59 grams of wet gluten were taken, and triturated with 3 grams of special kieselguhr, and 400 c.c. of cold 70 per cent, alcohol containing approximately 0-5 gram of stick sodium hydroxide. This was frequently shaken and allowed to stand over night (about 18 hours). Two hundred c.c. were then taken and filtered, the volume of the filtrate being 194 c.c. Tliis was rendered faintly acid by the addition of hydrochloric acid in slight excess, using phenolphthalein as an indicator, and evaporated to dryness in a weighed platinum dish, after weighing which the ash was determined. Tlie organic matter was calculated into percentage on the whole flour, and returned as dry gluten. To the remaining SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 791 alkaline 200 c.c., 10 per cent, sulphuric acid was added in measured quantity, until the solution was faintly acid to phenolphthalein. A very small quantity of chalk was then added to neutralise the excess of sulphuric acid. The solu- tion was frequently well shaken, and then allowed to stand over night. In the morning there was a coj)ious precipitate of glutenin which was filtered off. The filtrate was measured, and the total residue and ash determined as before. Allow- ing for the volume of sulphuric acid, the organic matter was calculated into percentage on the whole flour, and returned as gliadin. No. 14. Two grams wet gluten taken, pulled into very small fragments, 400 c.c. of OT per cent, sodium hydroxide in 70 per cent, alcohol, taken cold. Was shaken up frequently, took 24 hours to dissolve. Filtered 200 c.c., treated with hydrochloric acid, evaporated filtrate, and determined residue and ash as before for dry gluten. Remaining 200 c.c. rendered acid by measured 10 per cent, sulphuric acid, neutralised by very slight excess of chalk, stood over night. Filtered off glutenin, determined residue and ash in filtrate as before for gliadin. No. 15. Same quantities and process as No. 14, except that the gluten and alkaline alcohol were raised to boiling point, and shaken hot. The gluten quickly dissolved (within an hour), the solution was at once filtered and dry gluten and gliadin esti- mated as before. No. 16. Two grams of wet glutenin, being a portion of the residual mass of 10 grams obtained in the previously described experi- ment of extraction of gliadin from 20 grams of wet gluten. Treated as in No. 14 with alkaline alcohol. Dissolved fairly quickly in cold ; after two hours, decanted solution, and tri- turated the remaining solid in mortar till dissolved. Filtered and estimated dry gluten and gliadin as before. The following are the quantities of gliadin obtained, expressed as before : — No. 13. 7*86 per cent, of the whole flour. „ 14. 8*87 „ 15. 9-21 The next table contains further details of the last four tests : — Constituents. 13. 14. 15. 1 16. 1 Percentages. Wet Gluten on whole flour 35-71 35-71 35-71 35-71 Dry Gluten, by direct weighing, on whole flour 12-22 12-22 12-22 12-22 Dry Gluten, by evaporation of solution, on whole flour 11-76 11-88 11-81 — Gliadin, by evaporation of solution, on whole flour . . 7-86 8-87 9-21 — Crude Glutenin, by difference . . 3-90 3-01 2-60 — Components of the 2 Grams of Wet Gluten and Wet “ Glutenin,” Xo. 16. Grams. Water, with small quantity of Cellulose 1-341 1-335 1-339 1-227 Dry Gluten 0-659 0-665 0-661 0-773 Gliadin 0-440 0-492 0-521 0-271 Crude Glutenin i 0-219 0-173 0-140 0-502 792 THE TECHNOLOGY OF BREAD-MAKING. The gliadin obtained by solution of the whole of the wet gluten, and subsequent re-precipitation of the glutenin, is much more than that yielded by any of the processes of direct extraction of the gluten that have been described. For this there may be two reasons, either that none of the direct solution processes succeeds in extracting the whole of the gliadin, or that the glutenin once entirely dissolved is not completely re-precipitated on rendering the solution neutral. Some little light is thrown on this by test No. 16. As a result of direct treatment of 20 grams of wet gluten in the manner described, 2-3057 grams of gliadin were extracted. From the residual 10 grams of gluten not dissolved by the alcohol, 0-271 x 5 = 1-355 grams of gliadin were obtained by solution in alkaline alcohol and re-precipi- tation, making a total of 2-3057 + 1-355 = 0-36607 grams of gliadin, being equal to 6-53 per cent, of the whole flour. It will be seen therefore that after a very thorough exhaustion of wet gluten by alcohol, a further quantity of gliadin is yielded by solution and re-precipitation. 853. Further Tests on Starch Treatment of Gluten. — In view of the fact that grinding with wheaten starch successfully comminutes gluten, and that unlike chalk or kieselguhr, the starch exercises no adsorptive effect on the gliadin in solution, further experiments were made with this reagent. Using wet gluten from the same flour, mixtures, as below, were made up : — No. 1. Wet gluten, 2 grams ; wheat starch, 10 grams ; 70 per cent. alcohol, 400 c.c. used cold. The gluten and starch were rubbed down with a few c.c. of the spirit into a smooth creamy dough, which was then placed in a bottle with the remainder of the spirit, and shaken in the shaking machine over night, (about 15 hours). No. 2. Starch and cold alcohol only. Treated as No. 1. No. 3. Same quantities as No. 1, but alcohol used hot. Treated as No. 1. No. 4. Starch and hot alcohol only. Treated as No. 1. The solids of all had completely broken down when examined in the morning. The solutions were then filtered. They filtered very quickly and perfectly bright. Of the filtrates, 200 c.c. were taken, evaporated to dryness, and the residues weighed : — 0-206 Weight in grams 0-183 0-021 0-023 0-021 0-023 Net weight of Nos. 1 and 3. . 0-162 0-183 It will be noticed that extraction with hot spirit gave a higher result than with cold. The soluble matter, yielded by the starch only, agreed closely in Nos. 2 and 4. It was thought desirable, however, to further purify some starch ; and 1,000 grams were taken and washed with about 4 litres of hot 70 per cent, alcohol in the shaking machine for 24 hours. The starch was filtered from the spirit, pressed fairly dry, and again washed with a similar quantity of hot 70 per cent, alcohol for another 24 hours in the machine, and filtered and pressed. A third washing was then given with 95 per cent, alcohol in the same way, after which the pressed starch was carefully air-dried in a warm room. This is termed spirit-washed starch. Time Test . — In order to determine the time necessary for extraction, five tests of 2 grams of wet gluten, 10 grams of starch, and 400 c.c. of hot 70 per cent, alcohol were treated as before by making a dough and shaking with the spirit in the shaking machine. A sixth consisted of the spirit- SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 793 1 . 6 0*180 2 . 12 0*187 3 . 24 0*189 4 . 48 0*182 . 5 . 72 0*185 6 . 48 0*007 0*173 0*180 0*182 0*182 0*185 — 6*18 6*43 6*44 6*25 6*36 — 5*12 5*31 5*19 5*25 5*31 Nil. washed starch and alcohol only. Gliadin by weight was determined in 200 c.c. of the filtrate, and organic nitrogen in 100 c.c. by the Kjeldahl method. The following are the results : — Shaken for hours Gliadin by weight, grams Less, 0*007 for Starch cor- rection . . Gliadin by weight, per cent., on Flour Gliadin from Organic Nitrogen, per cent. . . The results agree very closely, and indicate that anything from 12 to 24 hours is a sufficient time for extraction. The organic nitrogen deter- minations also closely agreed, but using the 6-25 factor for proteins, the results run below the figures obtained by direct weighing. Quantity Test . — With the best time from last test, 24 hours, a number of experiments was made with varying quantities of wet gluten and starch. In all cases, 400 c.c. of hot alcohol Avas used for dough-making and extract- ion. The shaking was done in the shaking machine. The following are the particulars : — 2 grams ; spirit-washed starch, 10 grams. 3 55 5 5 5 5 lb ,, 4 „ „ „ 20 „ 5 „ „ „ 25 „ No. 1. Wet gluten, 55 2 . „ 55 3 . ,, ,, 4. necessary starch correction was made in each Gliadin by AA cight in grams Gliadin from 2 grams of Gluten Gliadin by AA'eight per cent, on Flour . 0-i86 0186 6-64 of the bright filtrate. The case. 2 . 3 . 4 . 0-275 0-355 0-459 0-183 0-177 0-184 6-55 6-34 6-55 Again, there is very elose agreement betAA^een the results obtained on AA’idely differing quantities, shoAAung that the solvent poAA'er of the spirit is Avell in excess of the amount required. But AAith the larger quantities of gluten, the grinding operation became very tedious, and the difficulty of avoiding the escape of comparatively large fragments from grinding Avas materially increased. 854. Standard Starch Method for Estimation of Gliadin. — ^The folloAving quantities, times, and method of AA’orking A\ ere ultimately adopted : Quantities, 2-2 grams AA et gluten, 11 grams of spirit-AA'ashed starch, 400 c.c. of 70 per cent, alcohol. After measuring the alcohol, 10 c.c. A\'ere reserved, and the remainder raised to the boiling point. In practice, this AA^as done by connecting the flask to a return spiral condenser, so that there AA^as no loss on the spirit commencing to boil. The AA^eighed gluten and about half the starch Avere then placed in the mortar and ground up Avith a feAV drops of the reserved alcohol into a thin dough. This AA^as stiffened by the addition of a little more starch, and tlie grinding continued, a little more alcohol AA^as then added, and so as again to make a thin dough, and then a little more starch. By this alternate addition of starch and alcohol, the gluten AA^as rapidly disintegrated, and finally aa ^s obtained as a perfectly smooth dough. This AA'as carefully transferred into a shaking bottle of 1 litre capacity. Any cold alcohol remaining AA^as added, and then the alcohol from the flask, AA'hich by that time Avill have got to the boil. The bottle AA'as then at once introduced into the shaking machine, aa here in practice it remained about eighteen hours. 794 THE TECHNOLOGY OF BREAD-MAKING. The following is a description and illustration, Fig. 118, of an installa- tion of shaking apparatus supplied to the authors by Gallenkamp & Co Ydien electricity is available, the most convenient source of power is a small electric motor A. This is started and regulated by the graduated switch, B. In order to slow down the speed, the motor is geared up with a countershaft, C ; which in turn drives the main pulley, D, of the shaking machine. The machine is made to hold six or ten bottles, each of which stands in a socket, E, of the right size. The sliding cap, F, is then placed dovTi to hold the bottle securely, and screwed in position by the screw, G. The svutch must be turned on so as to give the machine about sixty revolu- tions per minute. As the machine revolves, the contents of the bottle fall from the bottom to the top, and back again, about once a second. Fig. 118 . Shaking Apparatus. At the close of the shaking period, the bottle is removed, and the liquid poured on to a dry 10 inch filter. It filters very quickly and runs through quite bright. If 364 c.c. of the filtrate be taken, that quantity is equivalent to 2 grams of wet gluten. In order to save the spirit, the filtrate is boiled down in a flask connected to a condenser until the whole of the alcohol has distilled off. For this purpose the flask should be immersed in a hot bath of potassium carbonate solution ; in this the spirit boils rapidly, and the gliadin does not stick to the flask. The remainder in the flask is then transferred to a weighed glass basin and evaporated to dryness. The neces- sary starch correction is made and the results calculated as gliadin ex gluten. The weight of residuum thus obtained is a very convenient one (about 0-30 to 0-35 gram), but lesser quantities may be taken if wished. For example, SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 795 I -I gram of gluten, 5*5 grams of starch, and 100 c.c. of alcohol may be used for each test. Then, on evaporation of 91 c.c. of the filtrate, the gliadin ex 1*0 gram of gluten is obtained. 855. Application of Gluten and Gliadin Tests to Commercial Flours. — In order to illustrate the application of the various gluten and other tests to modern flours, the authors obtained a range of commercial samples from Messrs. W. Vernon & Sons, Ltd., millers, of which the following are the names, together with a description of the working properties of the flours as ascertained by baking tests : — 1. Millennium gave a loaf of rich bloom in crust, with a delicate creamy colour in crumb, and fine silky pile. Loaf was of fair volume, and gives best results in a hot oven. The bread keeps moist, and is of exceedingly good flavour. 2. To'p price. Slightly lower grade. Good bloom on crust, texture and colour of crumb very good. Slightly bolder loaf, of good flavour. 3. Town whites. Bright colour and good pile. Flavour good. Flour worked rather stronger than those preceding, and yielded rather larger loaf. 4. C.C.C. A good flour for second quality bread ; fair all-round pro- perties including colour. Strength good, without harshness in resultant bread. 'd 5. Town Households. A darker type of flour ; makes a good loaf, and suits in country and other districts where high colour is not a desideratum. The following are the results of analysis Protein and other Estimations of various Commercial Flours. Numbers — . 1. 2. 3. 4. 5. Percentages on Flour. Wet Gluten 32-83 34-36 35-47 34-67 34-77 Ratio of Wet to Dry Gluten 3-0 3-0 3-0 3-1 '3-0 Dry Gluten 10-72 1 1 -28 11-72 11-09 11-56 Non- Protein Matter in Dry Gluten 2-19 3-12 3-39 3-20 3-26 True Gluten 8-53 1 8-16 8-33 7-89 8-30 Gliadin ex Gluten 5-30 5-45 5-41 5-41 5-54 Glutenin ex Gluten Percentages on Dry Gluten. 3-23 2-71 2-92 2-48 2-76 Non-Protein Matter in Dry Gluten 20-43 27-66 28-92 29-76 28-20 Gliadin 49-44 ! 48-31 46-16 48-78 47-92 Glutenin . . Percentages on Flour. 30-13 24-03 24-92 21-46 23-88 Total Proteins 9-53 : 9-80 10-06 9-71 10-58 Gliadin ex Flour . . 5-29 5-20 5-38 5-25 5-40 Non-Gliadin Proteins (Glutenin, Albumin, etc.) Percentages on Total Proteins. 4-24 4-60 4-68 4-46 5-18 Gliadin ex Flour 55-51 53-06 53-48 54-07 51-04 Non-Gliadin Proteins 44-49 46-94 46-52 45-93 48-96 Recovered as True Gluten 89-51 83-26 82-80 81-25 78-45 Not recovered as True Gluten . . 10-49 16-74 17-20 18-75 21-55 Percentages on Flour. 14-56 14-52 14-38 14-40 14-06 ! Moisture . . 0-38 0-36 0-42 0-44 0-52 Ash Water absorption, Quarts per Sack 60 62 62 63 1 63 i In these flours the total gluten increases as the colour goes down, and keeps pace with their strength, but in true gluten No. 1 is slightly higher than any of the others. The gliadin in No. 1 is rather a higher proportion of the dry gluten than in any of the other flours. Looking at the total pro- teins as determined direct on the flour they run closely parallel to the dry 796 THE TECHNOLOGY OF BREAD-MAKING. glutens. The gliadins as obtained from the flour run very closely to each other, being highest in No. 1 and lowest in No. 5. The percentage of proteins not recovered as true gluten steadily increases as the flours diminish in quality. It would seem therefore that a comparison of the total proteins with the proportion thereof recoverable as true gluten has a close connection with the grade of the flour. The ash in all the flours is low, and precludes the possibility of mineral additions to the flour. The flours likewise gave no reaction when tested for the presence of bleaching agents. As might be expected with flours from the one mill, there is a close general resemblance between the whole of the grades. 856. Gluten and Gliadin Tests on Special Flours and Wheats. — The various gluten and allied tests were also applied to a series of single wheat flours, and typical wheats, with the following results. The wheat deter- minations were made on the finely ground meal of the whole grain, but in order to make the data obtained somewhat more comparable with those on flours, they have also been calculated to amounts present in 70 per cent, straight-run flours from such wheats. Single Wheat Flours. 6. From strong spring American wheat. 7. ,, French wheat, grovm in England, 1910 crop. 8. ,, Karachi wheat, 1910 crop. 9. ,, Taganrog wheat, 1909 crop. 10. ,, Bar-russo wheat, 1910 crop. 11. ,, New Russian wheat, 1910 crop. 12. Fourteen years old strong American flour. Protein and other Estimations on Single Wheat Flours. ' Numbers — . 6. 7. 8. 9. 10. 11. 12. Percentages on Flour. Wet Gluten 42-30 29-90 23-47 25-73 37-70 32-90 47-27 Ratio of Wet to Dry Gluten . . 2-8 3-0 3-4 3-0 3-3 3-3 1 5-1 Dry Gluten 15-02 9-75 6-77 8-52 11-34 9-98 9-20 1 Non-Protein Matter in Dry Gluten 4-25 1-95 1-40 0-90 2-07 1-63 6-13 True Gluten 10-77 7-80 5-37 7-62 9-27 8-35 3-07 Gliadin ex Gluten 7-36 4-98 3-75 3-49 6-91 5-75 2-84 Glutenin ex Gluten 3-41 2-82 1-62 4-13 2-36 2-60 0-23 Percentages on Dry Gluten. Xon-Protein Matter in Dry Gluten 28-29 20-00 20-68 10-56 18-25 16-33 66-63 Gliadin . . 49-00 51-07 55-38 40-96 60-93 57-61 30-87 Glutenin . . 22-71 28-93 23-94 48-48 20-82 26-06 2-50 Percentages on Flour. Total Proteins . . 12-95 10-19 8-14 13-78 11-46 12-12 13-15 Gliadin ex Flour 6-43 5-25 3-82 7-63 5-64 6-34 5-75 Xon-Gliadin Proteins . . 6-52 4-94 4-32 6-15 5-82 5-38 7-40 Percentages on Total Proteins. Gliadin ex Flour 49-65 51-52 46-93 55-37 49-21 52-31 43-72 Xon-Gliadin Proteins . . 50-35 48-48 53-07 44-63 50-79 47-69 56-28 Recovered as True Gluten 83-16 76-54 65-97 55-30 80-89 68-89 23-34 Xot recovered as True Gluten 16-84 23-46 34-03 44-70 19-11 31-11 76-66 iMoisture, per cent, of flour 12-86 12-14 12-00 12-70 12-60 12-46 Water Absorption, Quarts per Sack' 70 67-0 71-0 1 69-5 70-0 1 68-5 — Wheats. 13. Old Odessa, 1909 crop. 14. New Odessa, 1910 crop. 15. Manitoba. SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 797 16. Northern Plate (Rosario Santa Ee). 17. American Durum. 18. English Rivetts. 19. “ Azima (Russian). 20. ‘‘Ulka’^ (Russian). Protein and other Estimations on Typical Wheats. X'umbere — . 13 . 14 . 15 . 16 . 17 . 18 . 19 . 20. Percentages on Meal. Wet Gluten . . 33-27 25-50 .34-65 35-70 28-85 18 -.50 31-35 40-50 Ratio of Wet to Dry Gluten 3-0 2-7 2-9 3-0 ^ 2-9 3-0 3-1 3-1 Dry Gluten . . 10-96 9-49 11-88 11-86 10-00 6-21 10-07 12-98 Non-Protein Matter in Dry Gluten 1-96 2-04 2-54 2-23 2-40 1-26 1-94 3-30 True Gluten . . 9-00 7-45 9-34 9-63 7-60 4-95 8-13 9-68 Gliadin ejc Gluten . . 4-64 3-68 5-54 5-73 4-68 2-81 4-98 6-07 Glutenin ex Gluten . . , 4-36 3-77 3-80 3-90 2-92 2-14 3-15 3-61 Percentages on Dry Gluten. Non-Protein Matter in Dry Gluten . . . . . . 17-88 21-49 21-38 18-80 24-00 20-29 19-26 25-42 Gliadin 42-33 38-78 46-63 48-31 46-80 45-25 49-45 46-76 Glutenin 39-79 39-73 31-99 .32-89 29-20 34-46 31-29 27-92 Percentages on Meal. Total Protein 13-24 12-11 13-41 13-73 13-70 8-81 11-22 13-86 Gliadin ex Meal 5-07 4-11 5-60 5-99 4-15 2-97 4-76 5-38 Non-Gliadin Proteins 8-17 8-00 7-81 7-74 ! 9-65 5-84 6-46 8-48 Percentages on Total Proteins. Gliadin ex Meal 38-29 33-94 41-76 43-63 1 j 30-29 33-71 42-42 38-82 Non-Gliadin Proteins 61-71 66-06 58-24 56-37 ! 69-71 66-29 57-58 61-18 1 Recovered as True Gluten 67-97 61-52 69-65 70-21 1 55-47 56-18 72-46 69-69 Not recovered as True Gluten 32-03 38-48 30-35 29-79 44-53 43-82 27-54 30-31 Calculated on 70 per cent. Straight Flours. Wet Gluten , . 47-53 36-43 49-50 51-00 41-21 26-43 45-00 57-86 Dry Gluten . . 15-66 13-56 16-97 16-94 14-28 8-87 14-38 18-54 Non-Protein Matter in Dry Gluten 2-80 2-91 3-63 3-18 * 3-43 1-80 2-77 4-71 True Gluten . . 12-86 10-64 13-63 1.3-76 10-86 7-07 11-61 13-83 Gliadin ex Gluten . . 6-63 5-26 7-91 8-18 6-68 4-01 7-11 8-67 Glutenin ex Gluten 6-23 5-38 5-72 5-58 4-18 3-06 4-50 5-16 On examining the results on single wheat flours, excluding No. 12 for the moment, No. 6 gave the highest percentage of wet gluten, while Bar- russo, No. 10, was the next highest. The spring American was also highest in dry gluten, while No. 8, Karachi, was the lowest. In this particular flour the ratio of wet to dry gluten is very high ; Wood’s researches (paragraphs 455 et seq.) go to show that the more water there is in the gluten the nearer it is to actual disintegration. The absolute amount of gliadin ex gluten was high in both Nos. 6 and 10, while low in No. 8. But the relative pro- portion of the whole dry gluten which consisted of gliadin was comparatively liigh in No. 8. Comparing the total proteins with the dry gluten. No. 9 was the highest in the former and almost the lowest in the latter. Taganrog, No. 9, was very difficult to wash for gluten ; there was considerable frothing, and the wet gluten was very friable throughout the whole operation of separation. This flour is from a very hard wheat, and one which alone does not m.ake a good loaf. The gliadin ex gluten content was very low. On the other hand the gliadin ex flour was high. Taking Nos. 6 and 9, protein and gliadin determinations on the flour would place No. 9 the higher ; but gluten and gliadin ex gluten estimations at once show the marked superiority of the spring American flour. 798 THE TECHNOLOGY OF BREAD-MAKING. No. 12 sample, called “ Fourteen Years Old Strong American Flour/’ is of rather special interest. Rather over that length of time ago, one of the authors made some experiments on the feasibility of compressing flour into solid blocks by hydraulic pressure of several tons to the square inch. Among flours thus tested was a sample of strong American flour, of which several blocks were preserved. These were quite free from any mould or visible signs of decomposition, and a portion was accordingly subjected to this series of tests. On washing for gluten the dough broke down into a flocculent non-coherent deposit, and evidently was physically quite un- fitted for bread-making. By repeated washings on a hair sieve, and squeez- ing and coaxing the particles together, a flabby and scarcely coherent mass of wet gluten was obtained, which gave the unusually high percentage of 47-27. However most of this was evidently water, the ratio being 5-1, and the total quantity of dry gluten 9-20 per cent. Pursuing the investi- gation of the dry gluten a step further, it contained only 3-07 per cent, of true gluten, 6-13 per cent, consisting of non-separated starch. Nearly all the true gluten was composed of gliadin, the whole of the glutenin having disappeared. On turning to the direct determinations on flour, the proteins are high and are very nearly the same as in the strong American flour. No. 6 ; 13-15 against 12-95 per cent. The gliadin ex flour is very nearly as much as that of No. 6, 5-75 against 6-43 per cent., and would in ordinary analysis call for no very special remark. It shows up rather more in percentages on total proteins, where the figure is 43-72 against 49-65 in the No. 6 flour. But, according to Snyder (paragraph 448) this difference lies almost within the normal range since the same type of flour may have variations of proteins soluble in alcohol from 45 to as high as 70 per cent, with only minor variations in the bread-making value of the flour. The importance of these comparisons lies in the fact that the ordinary protein and gliadin ex flour tests scarcely serve to differentiate a spring American flour of the highest quality from a flour of the same origin, but so profoundly altered by fourteen years age as to have completely lost the physical properties so essentially characteristic of wheaten flour. On the other hand the abnormal character of this fourteen year old flour is at once revealed by an ordinary gluten test, and is in evidence throughout the whole series of subsidiary tests on the wet gluten. This is in striking con- trast with Chamberlain’s conclusion (page 311) that “the determination of gluten is not able to yield any information that cannot be gained either from the determination of total proteins or that of the alcohol-soluble and insoluble proteins.” It is submitted that if what may be called the purely chemical tests (Le., protein and gliadin determinations on the flour direct) fail so signally to indicate such remarkable differences as there are between these two flours, then they can be even less depended on as a means of gauging and estimating minor differences in character and quality. The gluten tests and their developments, on the contrary, afford exceed- ingly valuable information as to the general baking properties of the flour. Tlie wheats range from the strongest Manitoban to one of the weakest of English wheats, Rivetts. The first pair. Nos. 13 and 14, consist of Odessa of two successive years’ crops. The old was very satisfactory, but the new wheat was the reverse. The former was higher in wet, dry, and true gluten. Also the relative proportion of gliadin ex gluten was higher in the older wheat. The total proteins and gliadin ex meal were in general accord- ance with the gluten series of tests. The calculated percentages on 70 i:)er cent, straight flours are introduced with the object of showing approxi- mately the composition of the flours from the wheats, and permitting same to be compared with other flours. The Manitoba wheat. No. 15, is high in wet and dry gluten, and also in true gluten. The gliadin is high both abso- SOLUBLE EXTRACT, ACIDITY, AND PROTEINS. 799 lately, 5*54 per cent., and relatively, 46-63 per cent., of the dry gluten. On the meal, the total proteins, 13-41, and gliadin, 5-60 per cent., are also high. Throughout the whole series of tests the Rosario Santa Ee very closely resembles Manitoba wheats. (The American Durum, No. 17, refuses to come into line with any of the others. The wet and dry glutens are low, so also is the true gluten, 7-60 per cent. But the gliadin ex gluten is rela- tively high, being 46-80 per cent, of the dry gluten. Gluten testing would reveal the fact that this wheat was extremely hard ; and this, coupled with the low gluten, would indicate thorough conditioning of same before grinding. The total proteins of this wheat are high, 13-70., while the pro- portion recovered as true gluten was low, being only 55-47 per cent. The gliadin ex meal is very low. ^The extreme hardness of the grain very materi- ally affects all estimations made by solvents direct on the meal, and there- fore gluten and gliadin ex meal are both abnormally low. If the wheat be softened by standing some time after the addition of water, these soluble con- stituents would show an increase. Similarly, the great hardness of the wheat would react adversely on the flour if untreated, whereas effective condition- ing would very materially improve the flour. The English Rivetts, No. 18, is almost the antithesis of the preceding flour. Its gluten throughout is low, 18-50 per cent, wet, but contains a fairly high proportion of gliadin, 45- 25 per cent. The total proteins agree, being so low as 8-81 per cent., while the gliadin ex meal is do\m to 33-71 per cent, of the total proteins. The Azima, No. 19, has a fair gluten, with a relatively high percentage of gliadin ex gluten. The total proteins occupy a medium position, wdiile the gliadin ex meal is also fairly high. The Ulka wheat. No. 20, is distin- guished by a very high percentage of wet gluten, of a soft and what is some- times called “ pappy character. The ratio of w^et to dry gluten is high, 3-1, but the dry gluten is nevertheless the highest of the series, 12-98 per cent. The true gluten, 9-68, is also the highest of those in the table. The gliadin ex gluten is high absolutely, 6-07, and medium relatively, being 46- 76 per cent, of the dry gluten. In total proteins this wLeat is also the highest of the series wdth 13-86 per cent., wLile relatively the gliadin ex meal is rather above the average wdth 38-82 per cent. 857. Amide Nitrogen. — ^A method for the determination of amides in flour is described by Guess, and is given in paragraph 442. 858. Detection of Proteolytic Enzymes in Flour. — A process for the detection of protease, or proteolytic enzymes in flour, has been described by Ford and Guthrie, and is quoted in paragraph 461, page 326. CHAPTER XXIX. ESTIMATION OF CARBOHYDRATES, AND ANALYSIS OF BODIES CON- TAINING SAME. 859. Estimation of Sugar by Fehling’s Solution. — ^The composition and properties of the sugars are fully described in Chapter VI. It is there shown that maltose is capable of forming a red precipitate of copper sub -oxide in the reagent termed Fehling’s solution, while dextrin and starch cause no precipitate. (See, however, Brown and Millar’s conclusion that dextrin has a reducing power of about R. 5-8, paragraphs 179, and 262, page 133.) This reaction is not only of service in testing for maltose and certain other sugars, but also serves the purpose of quantitatively determining the amount of sugar present in a solution. As before, directions are first given for the preparation of the reagents, and then for the performance of the analytic operation. 860. Fehling’s Standard Copper Solution. — ^Powder a sufficient quantity of pure re-crystallised copper sulphate, and dry it by pressure between folds of filter paper. Weigh out 69*28 grams, dissolve in water, add I c.c. of pure sul^Dhuric acid, and make up the solution to I litre. 861. Alkaline Tartrate Solution. — ^Weigh out 350 grams of pure Rochelle Salt (potassium sodium tartrate), and dissolve so as to make about 700 c.c. of solution. Filter if necessary. Next dissolve 100 grams of sticks of pure caustic soda in 200 c.c. of water. If the solution is not clear, it must be filtered through a funnel fitted with a plug of glass wool. Mix the two solutions together, and make up the volume to 1 litre. When required for use, these solutions must be mixed together in equal proportions ; they then form the original Fehling’s solution. This solu- tion possessed the disadvantage of changing in character by being kept ; and hence the modification in which the Rochelle salt is only added to the copper sulphate immediately before the solution is required for use. Each c.c. of the mixed solution contains 0*03464 grams of copper sulphate, and was formerly considered equivalent to exactly 0*005 grams of pure dry glucose. 862. Action of Sugars on Fehling’s Solution. — ^A careful investigation has been made by Soxhlett of the action on Fehling’s solution of specially pure specimens of the various types of sugars : he finds as a result that the amount of precipitate formed depends not only on the quantity of sugar present, but also on the degree of concentration of the solution, the tem- perature at which the determination is made, and other conditions. Hence great care must be taken to work always in precisely the same manner, as it is only by so doing that comparative results are obtained. Sugar may be determined by Fehling’s solution either gravimetrically or volu metrically. A description of the gravimetric method is first given. The student should commence by practising the estimation on cane sugar, as this substance is easily obtained in a condition of purity. Cane sugar has no action on Fehling’s solution, but when heated gently with dilute 800 ESTIMATION OF CARBOHYDRATES. 801 acid is changed, by hydrolysis, into a mixture of glucose and fructose in equal quantities, viz. : — C12H22OH -f“ H2O = C6H12O6 “h C6H12O6. Cane Sugar. Water. Glucose. Fructose. Glucose and fructose both act on Fehling’s solution, precipitating copper sub-oxide, CU 2 O, in definite quantity. [ 863. Gravimetric Method on Cane Sugar. — ^Procure some of the sugar known as coffee crystals ; this is the variety of sugar sold by the grocer for use with coffee, and consists of large, colourless, well-defined crystals of almost pure cane sugar. Select some of these free from extraneous matter, powder them, and dry for a short time in the hot- water oven. Make up a one per cent, solution by weighing out I gram of the pure dry sugar, dis- solving it in water, and making up the volume to 100 c.c. Take 50 c.c. of this solution, and add to it 5 c.c. of pure fuming hydrochloric acid. For this purpose it is best to use a fiask graduated at 50 and 55 c.c. Place the fiask in a water bath, and heat until it reaches the temperature of 68° C. ; this operation should be arranged so as to occupy about 10 minutes. Next pour the contents of the flask into a 100 c.c. flask, and dissolve in it dry sodium hydroxide in small quantities at a time until the solution is slightly alkaline, testing after each addition with a small strip of litmus paper. Cool the flask and make up the contents to 100 c.c. with w^ater. The flask now contains a 0-5 per cent, alkaline solution of cane sugar converted into glucose and fructose. Add 25 c.c. of Fehling’s standard copper solution to the same quantity of alkaline tartrate solution, and mix the two thor- oughly. Take two beakers of about 6 ounces capacity, and pour into each 25 c.c. of the mixed Fehling’s solution. Next add to each 50 c.c. of boiling distilled water that has been boiling for about haff an hour. Stand the beakers in a water bath, the water of which is kept boiling by a bunsen ; allow them to stand for 7 minutes, and then look to see that no pre- cipitate has formed. Should a precipitate occur, the Fehling’s solution is impure, and is consequently no longer fit for use. Next add to each beaker 20 c.c. of the 0*5 per cent, sugar solution and replace in the water bath for 12 minutes. The precipitated cuprous oxide is best weighed on a counter- poised filter ; prepare, therefore, beforehand, two pairs of small Swedish filters, trimmed until each one of the pair exactly counterpoises the other, when tested in the analytic balance. Fold one of the pair of counterpoised filters, and filter the copper oxide rapidly from the solution ; the filtrate should still be of a deep blue colour. Collect the filtrate in a porcelain evaporating basin, and examine carefully in order to see if any traces of the precipitate have found their way through the paper ; if so, pour away the supernatant liquid from the basin, and wash any precipitate back on to the filter. Moisten the other of the pair of counterpoised filters with some of the filtrate, and wash both the filters rapidly with boiling water, and dry both in the hot-water oven. Tlie reason for treating the second paper with some of the filtrate is to cause each to be in as nearly as possible the same condition, so that it (the second) shall still counterpoise the first paper after being washed and dried. The filters should be dried for 12 hours and then weighed, the counterpoise paper being placed on the weight side. If wished, the cuprous oxide may be converted into cupric oxide and weighed as such. Or the oxide may be reduced to copper, either by the action of hydrogen or by electrolytic processes, and weighed in the metallic, form. For these and other methods, consult Allen’s Commercial Organic Analysis, vol. i. In order to understand the calculations involved in the estimation of 3f 802 THE TECHNOLOGY OF BREAD-MAKING. sugar by Eehling’s solutions, it will be necessary for the student to make himself thoroughly acquainted with the properties of the sugars as already described. The glucose and fructose produced by the action of dilute acid on cane sugar, as shown in the equation in a preceding paragraph, are sometimes grouped together as glucose, or grape sugar ; it is then said that one molecule of cane sugar (sucrose) produces, when inverted, two molecules of glucose. From the equation it will be seen that the molecular weight of cane sugar is 342, while that of the glucose formed is 360. It was formerly supposed that an exact number of molecules of CuO of the copper sulphate was re- duced to CU 2 O by the sugar ; hence we find the statement that two mole- cules of glucose reduce 10 CuO to 5 CU 2 O. Soxhlett’s researches, however, show that the reaction is not so simple, but, as before stated, varies, being dependent on the degree of the dilution of the reagent and other conditions. Different kinds of sugar, too, under the same conditions, reduce, weight for weight, different quantities of CuO to CU 2 O. Working in the manner directed, the reducing power of sugar on Eehling’s solution is, according to determinations by O’Sullivan and others ; — Cane Sugar has no reducing action. 1 gram produces and reduces. Glucose . . . . . . . . 1*983 grams of CuaO 2*205 of CuO. Cane Sugar after inversion . . 2*087 ,, ,, 2*315 ,, Maltose . . . . . . . . 1*238 ,, ,, 1*378 ,, The reason why the inverted cane sugar produces more CU 2 O, than does glucose is, that 1 gram of cane sugar, on inversion, yields more than a gram of glucose, the exact quantity being 1-052 grams. When only the one variety of sugar is present in a solution, the following factors may be used for calculating the amount of sugar from the weight of precipitated CU 2 O. Glucose . . . . . . . . . . . . y.-Jsa =0*5042 Cane Sugar after inversion .. .. .. 2-^X7=0*4791 Maltose . . . . . . . . . . . . 8=0*8077 Thus, suppose that in the analysis made with the 0-5 per cent, solution, the weight of the precipitated CU 2 O was 0-2075 grams, then ' 0-2075 X 0-4791 = 0-0994 of cane sugar. Theoretically, in 20 c.c. of the 0-5 per cent, solution there is 0-1 gram of sugar ; the results of the analysis give 99-43 per cent, of chemically pure sugar. If the estimation were made with perfect accuracy, this would show that the sugar contained 0-57 per cent, of moisture or other impurity ; the deficiency is doubtless in part due to error of analysis. The duplicate estimations made should agree closely. When making an analysis of a substance, the composition of which is known approximately, a quantity should be taken that contains as nearly as can be calculated 0-1 gram of inverted cane sugar, or 0-2 gram of maltose. In case the estimation shows that the amount of sugar differs widely from these quantities, a second determination must be made in which more or less of the substance is taken. In the presence of other carbohydrates capable of inversion by liydro- chloric acid, O’Sullivan recommends that cane sugar be inverted by means of invertase, which is without action on the other sugars, etc., which may j^ossibly be present. The method is described in detail in connection with the analysis of malt extract. 864. Volumetric Method on Cane Sugar. — ^When Fehling’s solution is intended only to be used gravimetrically, its exact strength is not a matter ESTIMATION OF CARBOHYDRATES. 803 of great importance, but when employed for volumetric estimations, its strength must first be accurately determined by titration with a standard solution of sugar. For this purpose the 0-5 per cent, solution of inverted cane sugar already described may be used. The sugar must be added to the Fehling’s solution, and not the Fehling’s solution to the sugar. The sugar solution is therefore placed in a burette, and in order that its contents may not get heated during the operation, the glass jet is attached by means of a piece of india-rubber tubing about 8 or 10 inches long. The burette may then be placed so as not to be vertically over the basin in which the Fehling’s solution is being heated. Measure out 5 c.c. each of the standard copper and alkaline tartrate solutions into a white porcelain evaporating basin ; add 40 c.c. of well- boiled boiling water, and heat the liquid quickly to the boiling point by means of a small bunsen flame. In order to test the purity of the Fehling’s solution, boil for 2 minutes ; there should neither be a precipitate nor any alteration of colour. Next add the sugar solution in small quantities at a time, boiling between each addition. As the operation proceeds, the deep blue colour of the solution disappears ; towards the end, add the sugar rnore cautiously, and after each boiling allow the precipitate to sub- side. Tilt the dish slightly over, note whether the clear supernatant liquid is still of a blue tint by observing the white sides of the dish through it. When the colour has entirely disappeared, the reaction is complete. The exact point may be determined with more exactitude by means of a dilute solution of potassium ferrocyanide, acidulated Avith acetic acid. With a glass rod put a series of drops of this reagent on a white porcelain tile ; wash the rod, take out a drop of the clear liquid from the dish with it, and add it to one of the drops of the ferrocyanide ; the slightest trace of copper produces a reddish-brown colouration. The results of the first estimation must only be looked on as approxi- mate, but having thus gained an idea of about how much sugar is required, the succeeding ones may be made more quickly, as almost all the sugar may be added at one time. Thus, if 9-6 c.c. of sugar solution Avere required in the first trial, then in the second from 8-5 to 9-0 c.c. may be run in at once, and then the solution added more carefully as the end of the reaction is reached. Provided the Fehling’s solution is of normal strength, then 10 c.c. = 0-0500 grams of glucose or invert sugar. 10 c.c. = 0-0475 ,, ,, cane sugar (after inversion). 10 c.c. = 0-0801 ,, ,, maltose. The difference betAA^een the cane sugar and glucose is here again ex- plained by the fact that cane sugar produces on inversion more than its AA'eight of glucose ; 0-0475 gram of cane sugar yields 0-05 gram of glucose. Working with a 0-5 per cent, solution of cane sugar, each c.c. contains 0-005 gram, and 9-5 c.c. contain 0-0475 gram of sugar ; 10 c.c. of the Feh- ling’s solution should therefore require for its complete reduction 9-5 c.c. of the sugar solution. As the Fehling’s solution is rarely of the exact strength, its equivalent in cane sugar must be noted so as to be used in each determination. Sup- pose the 10 c.c. of Fehling’s solution required 9-3 c.c. of the sugar solution, then AA^e knoAV that 10 c.c. is equivalent to only ff = 0-9789 of the re- spective quantities of different sugars given above. The exact strength of the Fehling’s solution should be noted on the bottle, together AAuth the date AA'hen the titration Aras made ; the solution should be frequently tested against the solution of pure sugar. The quantity of sugar found must therefore be multiplied by 0-9789. An example AAill make this clear. A 804 THE TECHNOLOGY OF BREAD-MAKING. 0-5 per cent, solution of a commercial sugar was tested volu metrically, when 11-4 c.c. of the sugar solution were required to completely reduce 10 c.c. of the Fehling’s solution. By titration 10 c.c. of the Fehling’s solu- tion are known to be equivalent to 0-9789 of 0-0475 = 0-0465 of pure cane sugar ; that quantity is therefore present in 11-4 c.c. of the 0-5 per cent, solution. A 0-5 per cent, solution contains 0-005 gram of sugar, so that 11- 4 c.c. contains 0-0570 gram of the sugar. As 0-0570 gram of the sample contains 0-0465 gram of sugar, the percentage of pure sugar in the speci- men is 81-58. The analysis would appear in the note-book thus : Volumetric determination of pure sugar in a commercial sample of cane sugar. Inverted and made up to 0-5 per cent, solution. 11-4 c.c. required to reduce 10 c.c. of Fehling's solution, which = 0-0465 gram of pure cane sugar. 0-0465x100 11*4 xO 005 ^ cent, of pure sugar.'’ 865. Estimation of Maltose in Wheats or Flours. — The method of pro- cedure is much the same as with cane sugar. The principal point is to obtain a solution of the right strength. Assuming that an aqueous infusion of wheat contains an average amount of 2-5 per cent, of maltose, then 100 c.c. of a 10 per cent, solution of the meal or flour contains 0-25 gram of maltose, so that 80 c.c. of the 10 per cent, solution are required in order to furnish an approximate amount of 0-2 gram of maltose. For each quantitative estimation, take 25 c.c. of Fehling's solution, 10 c.c. of Avater, and 80 c.c. of the clear 10 per cent, solution of the meal or flour. These quantities give the same degree of dilution as those directed to be used in the estimation of cane sugar ; proceed exactly as in the determination of that substance. Having weighed the precipitate of CU 2 O, multiply by the factor 0-8077 ; the result is the quantity of maltose in 80 c.c. of a 10 per cent, solution of the meal or flour. As 80 c.c. of such a solution contains the soluble portion of 8 grams of the meal, the percentage is obtained by multiplying by 12- 5. In making this estimation the soluble proteins of the grain are kept in solution by the alkali of the Fehling’o solution. They may if wished be removed by boiling and Altering the 10 per cent, solution. Put about 100 c.c. of the solution in a beaker, take the weight, and then boil for about five minutes ; replace on the balance and make up to the original weight with distilled water. Filter off the coagulated proteins by passing the liquid through a dry filter ; the filtrate is a 10 per cent, solution, minus the proteins coagulated by boiling. If maltose is to be determined volumetrically, the solution should always be first freed from coagulable proteins in the manner just described. Take 10 c.c. of the mixed Fehling’s solution, add 20 c.c. of Avater, and run in the clear 10 per cent, solution of the meal or flour until the reaction is complete, exactly as Avas done AAuth the inverted cane sugar. The less quantity of Avater is added because of the maltose solution from the meal or flour being so A^ery dilute. In case the estimation of maltose is being made in a much stronger solution than that obtained by treating a meal AA'ith 10 times its AA'eight of AA'ater, dilute the solution doA\m until it contains approximately about one per cent, of maltose, and then AV'ork AA'ith exactly the same quantities as Avere directed for the inverted cane sugar 0-5 per cent, solution. The estimation of maltose in AA'heats and flours is principally of value as a means of judging the amount of alteration AA'hich the starch has under- gone : that a sugar analagous to cane sugar is also present is demonstrated ESTIMATION OE CARBOHYDRATES. 805 by the experiment quoted in paragraph 370, page £08, in which an addi- tional precipitate is obtained as a result of treatment with hydrochloric acid. It must be remembered that with such an aqueous infusion there is always some change due to enzymic action on the starch of the wheat. If neces- sary, this action is obviated by destruction of the enzymes as a preliminary to the test. (See paragraph 461, page 326.) 866. Estimation of Dextrin. — ^Most substances which contain maltose contain also dextrin ; thus the two are both found in wort produced from malt, and also in starch solutions that have been subjected to diastasis. Dextrin has no action (or but little) on Fehling’s solution, but by prolonged treatment with an acid is converted into maltose, and ultimately into glucose. When maltose and dextrin are simultaneously present in a liquid, other carbo- hydrates being absent, the maltose is estimated in a portion as already described ; another portion is treated with acid, by which both dextrin and maltose are converted into glucose. A second estimation of the copper oxide reducing power is then made. The weight of precipitate will be found to be considerably more than in the first estimation. This is due, in the first place, to the fact that glucose precipitates more CU 2 O than does maltose. The maltose originally present must be calculated into glucose, and the amount of precipitate due to it subtracted from the weight found in the second estimation : the remainder is reckoned as glucose produced by the hydrolysis of the dextrin ; the percentage may be then obtained by calcu- lation. Unfortunately, it is difficult to determine the exact point when the whole of the dextrin has been changed into glucose. When carefully worked the process is, however, sufficiently accurate for most technical purposes, and yields comparative results. The method is largely employed for the determination of dextrin in the worts made for malt essays. There follows a modification of the process adapted to the determination of dextrin in meals and flours. Having made a solution for the determination of maltose, take the same quantity of the solution as required for that estima- tion, viz., 80 C.C., and add to it 2 c.c. of dilute sulphuric acid (1 part concen- trated acid to 8 of water), stand the mixture in a water bath, and heat to boiling for 4 hours. At the end of that time neutralise carefully with ■caustic potash solution (KHO), and proceed to estimate glucose by Feh- ling’s solution precisely as before. The excess of glucose in the second solution over that produced by the maltose in the first requires to be calcu- lated back to dextrin. It must be remembered that glucose is produced from dextrin according to the following equation ; — Ci2H2oOio 2 H 2 O = 2C6H12O0 Dextrin. Water. Glucose. Molecular weight =324. Molecular weight =360. Tlierefore, every 360 parts of glucose thus produced represent 324 parts of dextrin in the original solution, or 10 of glucose = 9 parts of dextrin, so that glucose formed from dextrin X y^o = dextrin. As already stated, this method must only be looked on as giving results sufficiently accurate for technical purposes. A useful alternative method of estimating dextrin depends on the fact that it is only very slightly soluble in alcohol of the strength of ordinary methylated spirits, whereas maltose, glucose, etc., are fairly soluble under the same conditions. The method is applicable to the soluble extracts of bread and flour, malt extracts, and similar preparations. When there are many such estimations to be made, a fairly large quantity of methylated .spirits, say a gallon, should be redistilled (see paragraph 878), tested against purified dextrin, and reserved for this purpose. To purify dextrin, take some 806 THE TECHNOLOGY OF BREAD-MAKING. of the best light -coloured dextrin of commerce, and dissolve in water to about a 15 per cent, solution. Pour some of this, in small quantities at a time, in about a litre of redistilled spirit in a large flask, shaking vigorously between each addition. Dextrin will be precipitated, and should be finely divided, if in sticky clots the solution has been used too strong, and must be diluted. Filter off this precipitate, wash with alcohol, redissolve in water, and again precipitate with a large quantity of alcohol as before. Wash and carefully dry ; the resultant purified dextiin should be colourless and tasteless (save for a slight flavour from the spirit). Dissolve OT gram of the dextrin, and make up to 10 c.c. in water ; add this quantity to 125 c.c. of the redistilled spirit, and shake well : there should be a slight precipitate. Filter and evaporate 50 c.c. to dryness in a weighed dish, and thus deter- mine the amount of dextrin dissolved by the particular sample of spirit. Note same in calculated weight of dextrin held in solution per 270 c.c. In making a determination, prepare, if possible, a solution of such a strength that 20 c.c. shall contain approximately 0-2 gram of dextrin. Add this to 250 c.c. of redistilled spirit in a flask, cork, and shake up : allow to stand a few hours, then pour off the clear, supernatant liquid on to a counterpoised filter, disturbing the precipitate as little as possible. Add 100 c.c. more of redistilled spirit to the precipitate, and shake vigorously, then transfer the dextrin to the filter, washing out the paper with the clear spirit filtrate ; dry and weigh against the counterpoise, which must be washed successively with the first and second spirit filtrates. Add on to the Aveight thus found the 270 c.c. solubihty correction (The 100 c.c. of spirit used for washing does not redissolve any weighable quantity of the precipitated dextrin.) At times the dextrin precipitate sticks some- what to the flask : . in such cases rinse first with a little alcohol, and then dissolve out with a small quantity of water, and evaporate to dryness in a weighed dish. Add the quantity thus found to the total. As in some cases the spirits may precipitate proteins as well as dextrin, it is advisable, where special accuracy is required, to make a nitrogen deter- mination in the dry precipitate. For this purpose fold up the filter paper, and Kjeldahlise it together with the precipitate in the usual manner. Deduct the weight of protein from the total weight of precipitate. Occasionally the proteins present will not separate, and produce an opalescent liquid which filters badly and extremely slowly. In this case make a fresh estimation, using stronger spirit, say 92-94 per cent., for precipitation. Let it stand at least 12 hours, or till clear, then wash the precipitate three times by decantation in the flask, shaking vigorously, and allowing to subside each time, using for this purpose the weaker spirit. Collect and weigh as before. In this case make a special test for the correction Avith some purified dextrin, operating in the same manner, and evaporating down knoAAm fractions of the lots of spirit used. It should be added that alcohol precipitates in this manner not only dextrin, but also other gum-like bodies present, Avhich are frequently returned in analysis as “ indeterminate matters.'" 867. Polarimetric Estimations. — ^In addition to the method already described of estimating maltose and dextrin by means of Fehling's solution, there is a second process in which certain optical properties of these bodies are employed in the determination of dextrin, instead of hydrolysing that substance into glucose by means of dilute acid. This particular modifica- tion is of special value as a part of the process, to be hereafter described, of the estimation of starch, consequently it requires careful explanation. As has been already stated, the sugars, in common Avith several other bodies, are capable of rotating the plane of polarisation of a ray of light.. ESTIMATION OF CARBOHYDRATES. 807 They possess this property not only in the solid state, but also when in solution ; further, the amount of rotation is very nearly proportional to the degree of concentration of the solution. 868. Specific Rotatory Power. — ^The angular rotation of a ray of polarised light by a plate of any optically active substance, I decimetre (3-937 inches) in thickness, is termed its “ specific rotatory power."" In most substances this has to be obtained by calculation, because of the difficulty of getting transparent plates of a sufficient thickness. A solution of known strength is prepared, and from tlie rotatory power of this solution the specific rota- tory power may be calculated. The rotatory power of solutions of the same strength may vary with the temperature, and also with the solvent employed, hence it is necessary to note the strength of the solution at the time of the estimation, and also the solvent used. The apparent or sensible specific rotatory power of a substance is found by dividing the angular rotation observed in the polarimeter (a) by the length of the tube in deci- metres (/, usually = 2) in which the liquid is observed, and by the degree of concentration (c), that is the number of grams in 100 c.c. of the liquid. S being the specific rotatory power, then the above is represented by the formula — g ^ a ^ lOOt* I ~l X c The rotatory power of a substance depends on the nature of the light used ; as the instrument to be described is one in which the yellow monochromatic light of the sodium flame is employed, all numbers given will be for light of that description, which is often indicated by the symbol Sd. In measuring rotatory powers of sugars it has been found convenient to take a plate of quartz, I millimetre in thickness, as the standard of com- parison. According to the latest and most accurate measurements, such a plate produces an angular rotation of 21° 44' = 21-73° for the sodium flame (Sd). The strength of the cane sugar solution which, in a tube 2 decimetres in length, shall exercise the same rotary power, is that equal to 16-350 grams of sugar in each 100 c.c. of the solution. Sd 100 X 21-73 2 X 16-350 66-45° as the specific rotatory power of cane sugar. All sugars do not rotate the plane of polarisation in the same direction : thus, some twist it to the right, or in the direction of the hands of the clock, others twist it towards the left. The terms dextro- and Isevo -rotation are applied to the right-handed and left-handed rotation respectively. Also the symbol + is used to represent dextro- and — to represent laevo- rotation. The specific rotatory power of substances varies somewhat with the degree of concentration of the solution. For a solution of approxi- mately 10 per cent, strength, that of substances of importance in conjiec- tion with the chemistry of wheat and flour is appended •. — Specific Substance. Cane Sugar Formula. C 12 II 22 G 11 Rotary Power. + 66-5° Maltose Ci2H220ii +138-3° Glucose, Dextrose C 6 H 12 O 6 + 52-5° Fructose, Laevulose C6H12O6 - 98° at 15° C. Invert Sugar 2C6H12O6 - 22-7° at 15° C Dextrin GeHioGe +200-4° 869. The Polarimeter. — In order to measure the amount of rotatory power possessed by various bodies, an instrument known as a polarimeter 808 THE TECHNOLOGY OE BREAD-MAKING. is employed (sometimes spoken of incorrectly as a “ polariscope There are various forms of this instrument, but one of the simplest is that known as the half -shadow polarimeter or “ saccharimetre a penombres."' A well- known make of this instrument is that manufactured by Schmidt & Haensch of Berlin, and supplied by C. Baker, Holborn, which is illustrated in Fig. 119. Fig. 119. — Half-shadow Polarimeter and Vernier. By means of a specially constructed bunsen lamp, a sodium flame is produced, and toward this the end, S, of the polarimeter is directed while employing the same. When using the polarimeter it is well to work in a room from which all light other than that of the sodium flame is excluded. The instrument consists essentially of a tripod support, carrying a hori- zontal frame, in which is placed the tube filled with the solution under examination, and having at the one end, P, the polarising prism, and at the other the analyser. A, together with a small magnifying arrangement used as an eye-piece, P. Immediately behind the analyser, A, is the disc, K, on which is en- graved the scales of the instrument. Follow- ing this is the trough with hinged lid, in which are placed the tubes containing the liquid under examination. B Fig. 120. — Polarimeter Tube. 870. Polarimeter Tubes. — ^These are now usually made of glass and are fitted at the ends with brass caps. Those most commonly used are exactly 20 centimetres in length from end to end inside the caps. The left-hand illus- tration, Fig. 120, represents the tube with the ends screwed on ; the other shows the tube in section. Each cap contains a glass plate which fits accurately to the end of the tube ; above the glass plate is a washer of leather ; on screw- ing on the cap this washer exerts an equable pressure on the glass plate, and so makes a water- tight joint. The mistake must not be made of placing the washer inside instead of outside the glass plate. When using the tube, it is first cleaned, then dried, or rinsed with a few drops of the liquid under examination ; one of the caps is next screwed on. The tube is then filled with the solution, any bubbles are allowed to escape, and then the second glass plate is slidden over the end and screwed tight by ESTIMATION OF CARBOHYDRATES. 809 means of] the cap. If properly filled, the tube should contain no air, neitherjshould it leak. If there should be any tendency to leakage, it may be prevented by very slightly greasing the ends of the tube. It will be evident that such a tube contains a layer of the liquid exactly 20 centimetres in length. 871. Polarimeter Tube, with Thermometer. — ^Fig. 121 shows a polari- meter tube of slightly different construction : it is in the first place 22 instead of 20 centimetres long. On the top there is a tubulure, by which a thermometer is inserted in order to determine the temperature of tlie solution at the time the estimation is made. The use of this particular form of tube will be described hereafter. Fig. 121. — Polarimeter Tube, with Thermometer. 872. Verification of Zero of Polarimeter. — ^The first operation to be performed in starting work with a new polarimeter is to verify the zero of the graduated scale of the instrument. The commonest and most generally useful form is a scale graduated into angular degrees, namely, 90° to the right angle, or 360° to the whole circle. In addition to, or instead of, the angular scale, some instruments are provided with a sugar scale. This latter is a scale of 100 degrees, so arranged that when a specified quantity of cane sugar is taken, the number of degrees indicated by the polarimeter represents the percentage of pure sugar without any calculation. For present purposes, the angular scale only need be considered. On the dial of the instrument being described there is engraved a whole circle of 360° graduated into half -degrees, the zero being on the right-hand side, and the degrees reading upward and to the left, right round to 360. There are two fixed vernier scales, n, n, one on each side of the dial. Two magnifying glasses, I, I, are provided in order to read the scales. By means of the milled head, T, the dial may be readily rotated in either direction, together with the eye-piece and analysing prism. To make this verification of the zero, commence by placing some fused sodium chloride in the platinum spoon of the bunsen lamp, then light the bunsen, and turn the spoon into the flame, so that an intense yellow light is produced. Arrange the axis of the instrument in the direction of the flame, so that on looking through the eye-piece a brilliant yellow field is seen. Next fill one of the 20 centi- 810 THE TECHNOLOGY OF BREAD-MAKING. metre tubes with distilled water, and put it in its proper position in the polarimeter. Place the zero of the vernier in coincidence with that of the scale, and look carefully through the instrument in order to see whether both halves of the field are equally illuminated. Turn the milled head, T, very slightly in either direction ; one half of the field becomes dark, and the other lighter. Now focus the eye-piece, T, by drawing it out or pushing it in until the vertical line, dividing the two halves of the field, is sharply defined. Having focussed the eye-piece, turn T back again until the two halves of the field are equally illuminated : note the position of the vernier and see whether it coincides with the zero of the scale. (For reading the vernier use the eye-piece, I, drawing it in or out until the scale is sharply in focus.) Should the two agree, once more displace T, and again bring it back to the position in which the two halves of the field are equally bright, and read the vernier. Observe whether the two readings of the zero are alike. If the zero of the instrument is found correct, well and good, but if not, turn T until the zero of the vernier is exactly over that of the scale ; then slacken the milled heads immediately underneath A, and screw in or out, until the two halves of the field are of the same depth of tint. Make this adjustment most carefully ; when once made, re-tighten these milled heads until the tube A is securely fixed in the correct position. The instru ■ ment will then be permanently in adjustment. The pointer, A, is used for the purpose of regulating the degree of sensi* tiveness of the instrument. The nearer the pointer is to zero the darker is the half-shadow side of the field for the same amount of angular displace- ment of the zero of the angular scale, and therefore the more sensitive is the reading. With absolutely transparent solutions, h may be fixed at zero, but with solutions that are not quite clear, the pointer must be moved slightly away from zero so that sufficient light may pass through. When h is moved, the zero of the dial plate must again be adjusted by means of the milled heads under A. Usually, when the instrument is received from the makers, h is arranged in the most convenient position for general work, and the zero of the instrument adjusted accordingly. 873. Method of Reading with Vernier. — ^To those not accustomed to the use of the vernier for the purpose of accurately reading graduations on instruments of exactitude, a few words of explanation of that device will be acceptable. The vernier is a small scale which slides over the gradua- tions of the principal scale of the instrument. On the vernier a length, equal to 29 of the half-degree graduations on the fixed scale, is divided into 30 equal parts. As a consequence, each division on the vernier is exactly twenty-nine thirtieths of each on the fixed scale. Bearing this in mind, let us see how the vernier is used in actual work. Suppose that with the polarimeter a sugar solution is placed in the instrument, and the analyser turned until the two halves of the field are illuminated equally. It now becomes necessary to read off the number of degrees through which the analysing prism has been rotated. On looking at the scale, we find that the zero of the vernier is between, say 94 and 94-5 degrees. Look along the vernier scale in the direction of the 95 until one of the graduations on the vernier exactly coincides with one on the fixed scale. If this graduation on the vernier is 7 from the zero, then the accurate reading of the polarimeter is 94® 7' (94 degrees 7 minutes, the minute being of a haK-degree, as there are 60 minutes to the degree). In fact, whatever number graduation on the vernier coincides with one on the other scale, the^ number of that particular vernier graduation represents the fraction of a half-degree in minutes. This will be seen to be the case on reflection. A fuller explanation of the vernier may be found in GanoFs or other work on “ Physics.'' ESTIMATION OF CARBOHYDRATES. 811 In Fig. 119, the vernier scale is shown to the right of the illustration. In that particular instrument the main scale is divided into quarter-degrees and the vernier scale into 25 parts. Each graduation on the vernier scale is therefore equal to one twenty-fifth of a quarter-degree, or 0-01°. 874. Polarimetric Estimation of Cane Sugar. — ^As a matter of practice the student will do well to make some polarimetric estimations on pure cane sugar. For this purpose powder finely some clean cofiee sugar crystals, and dry for a short time at 100° C. Make up respectively 10 and 20 per cent, solutions in distilled water, 100 c.c. of each. Fill a tw^o -decimetre tube with the 10 per cent, solution, which must be perfectly clear and transparent. Prepare the polarimeter for working and introduce the tube. By means of the milled head, rotate the analyser to the right until the point is attained at which the change from illumination of the one side of the field to that of the other occurs with great sharpness. Turn the milled head very slowly, and observe carefully the exact point at which equal illumination is reached. Read off the number of degrees by means of the vernier on the right-hand side of the instrument ; then shift the analyser, once more bring it back to the neutral point, and again read. The two readings should agree to within 2 minutes (2'). If the sugar be absolutely pure, and the operation performed correctly, the reading should be precisely 13° 18'. This signifies that the sample under examination contains exactly 100 per cent, of pure cane sugar. Similarly, if the polarimeter stood at 12°47', we should state that the sample contained less than 100 per cent, of pure sugar. As angular measurements are now frequently expressed in decimals of a degree instead of in minutes, the following table for the conversion of one into the other may be of service *. — Minutes — decimals. Minutes = decimals. Minutes = decimals. 1 0-016 11 0-183 21 0-350 2 0-033 12 . . 0-200 22 . . 0-366 3 . . 0-050 13 0-216 23 . . 0-383 4 0-066 14 0-233 24 . . 0-400 5 0-083 15 0-250 25 . . 0-416 6 0-100 16 0-266 26 . . 0-433 7 0-116 17 . . 0-283 27 . . 0-450 8 0-133 18 0-300 28 . . 0-466 9 0-150 19 . . 0-316 29 0-483 10 . . 0-166 20 . . 0-333 30 . . 0-500 The figures 13°18' and 12°47' become 13-30° and 12-783° respectively. The percentage of pure sugar in the second case can readily be obtained by calculation : — 12-783 X 100 ^13-30 ' = 96-1 per cent. With the 20 per cent, solution the reading is practically double (subject to the fact that there is a very slight diminution of specific rotatory power with increase of concentration of cane sugar). If the sugar be pure the reading is 26°36' or 26-6°, or with the same degree of impurity as before supposed, 12°47' becomes 25°34' or 25-566°. 874. Polarimetric Behaviour of Inverted Cane Sugar. — ^It has been already stated that the operation of treating cane sugar with an acid, and so causing it to precipitate cuprous oxide from Fehling’s solution, is termed “ inverting ’’ the sample. The reason is, that a solution of sugar thus treated rotates the plane of polarisation to the left instead of to the right. Take a flask having two marks on the neck, one at 50 and the other at 55 812 THE TECHNOLOGY OF BREAD-MAKING. C.C., fill up to the 50 c.c. mark with the sugar solution, and then add 5 c.c. of pure fuming hydrochloric acid. Next heat the flask in a water bath until its contents have acquired a temperature of 68° C. ; this operation should be so arranged as to occupy about 10 minutes. Cool the flask by immersion in cold water. Fill the 22 centimetre tube with this solution, insert the thermometer, note the temperature and read the amount of rotation, which will be left-handed, with the polarimeter ; that is to say, the dial must be turned toward the left instead of the right in order to reach the critical point of equal illumination. That having been done, the reading must be taken : in the instrument described, the point on the left hand of the dial, corresponding to zero, is 180 degrees, and the reckoning is usually taken from that point. Working with the 10 per cent, sugar solution, and assuming its purity, and that the thermometer registers 15° C. as the temperature of the solution, then the scale of the polarimeter read on the left-hand vernier stands at 175°28'. As 180 corresponds to zero, this amounts to a minus reading of 4°32'. 180° - 175°28' = 4°32' = 4-533°. In order to distinguish them as left-handed readings, the minus sign is placed before the reading thus, — 4°32' or — 4-533°. The reason for having a tube 22 centimetres in length will be evident ; the addition of 5 c.c. of acid to 50 c.c. of sugar solution will have diluted the solution to } ^ of its former volume. When the reading is taken in a 22 centimetre tube, that also is of the length of the 20 centimetre tube, consequently a depth of liquid equal to 20 centimetres of the sugar solution before inversion is looked through. Working in this manner, no calculation is necessary for the dilution resulting from the addition of the acid. Careful observation has shown that a solution of cane sugar which before inversion had a right- handed specific rotatory power of + 66-5°, gives after that operation a rotation of 22-7° to the left, provided the temperature of the inverted solu- tion is 15° C. Calculated in terms of specific rotatory power, the plane of polarisation is therefore, by the operation of inversion, rotated through 89-2°. As has been stated, inversion produces from the one molecule of cane sugar two molecules of glucose, one each of dextro-glucose and Isevo- glucose. This latter body has a diminished rotatory power at high tem- peratures, and hence it becomes necessary to read the temperature at which the observation is made. At a temperature of 0° C. the range of inversion is 94-1°, and diminishes approximately by one angular degree for every three degrees rise in temperature, or 0-33 of an angular degree for each degree rise in temperature. This rate of diminution gives 89-2° for the temperature of 15° C. If possible the readings of the inverted sugar solu- tion should be taken at 15° C., or failing that, at as nearly as possible that temperature. The correction per degree amounts to approximately gyo = 0-0037 of the total range of inversion. Thus if the reading be taken at 18° C., the angular range will require to be increased by ^fo of its total cjuantity. A convenient way of expressing rotatory power is in that of “ Rotatory power per gram in 100 c.c., the observations being made in a 2 decimetre tube.'' The figures thus obtained are one-fiftieth of the specific rotatory power, and are as follows •. — Rotatory Power per Gram. Cane Sugar 1-33° Maltose 2-77° Glucose, Dextrose 1-05° Fructose, Lsevulose . . — 1*96° at 15° C. Invert Sugar . . -045° at 15° C. Change due to Inversion of Cane Sugar . . 1-78° at 15° C. Dextrin 4-01° ESTIMATION OE CARBOHYDRATES. 813 Thus in the 10 per cent, pure sugar solution, the reading of 13-3°, on being divided by 1-33 gives 10, showing that there are present 10 grams of sugar in the 100 c.c. Similarly the amount of change as observed is 13-3 + 4-533 - 17-833. On dividing this by 1-78, the result is again 10, confirming the previous determination of there being 10 grams of sugar present in the 100 c.c. In event of the sugar containing 10 percent, of moisture, the right hand reading would only amount to 11-97° or of 13-3° ; similarly, the reading after inversion and calculation to 15° C. would amount to — 4-08°. The amount of change would then be 11-97 + 4-08 = 16-05. On dividing this as before by 1-78, the result is again 9, confirming the determination by direct reading on the unaltered sugar. If, on the other hand, some substance, as glucose, were present which is not capable of inversion by the method adopted, then the left-hand reading would be less than the theoretical amount for cane sugar. Thus the polarimeter affords not only a means of observing the percentage of sugar present in a sample, but also gives valuable indications as to the nature of the impurity. In making polarimetric estimations of cane or other sugar or saccharine body, 20 grams may be taken and made up to 100 c.c. In the case of cane sugar, the polarimeter readings may be divided by the following factors ~ = 0-266 for direct reading, and = 0-356 for amount of change due to inversion. The result is the percentage of sugar direct. 875. Polarimetric Determination of Dextrin and Maltose. — ^Attention must next be directed to the method of using the polarimeter for estimating the amount of dextrin in a liquid containing both dextrin and maltose. Should the liquid contain any coagulable proteins, they should first be removed by heating a known weight of the liquid for a few minutes in the hot-water bath, making up the lost weight with distilled water, and then filtering. It may happen that the liquid is not sufficiently clear to be transparent in a layer of so much as 20 centimetres ; it may then be clarified by treatment with animal charcoal in the following manner : — Add to the solution, in a flask, about one-fifth of its volume of powdered, recently ignited, pure animal charcoal.^ Shake up vigorously for a few minutes, and pass through a dry filter. Return the filtrate to the paper until it comes through perfectly clear. It is usualty preferable, however, instead of treating with charcoal, to dilute the liquid with water, as charcoal appar- ently exercises an absorbent effect on some of the carbohydrates. Subject to this reservation, for the polarimetric reading, as concentrated a solu- tion as possible should be taken, and the observation made in the 20 centi- metre tube. After reading with the polarimeter, dilute down to the right strength, and estimate maltose by Fehling’s solution. Knowing the quantity of maltose present, in order to calculate the pro- portion of the polarimetric effect due to dextrin, the amount of rotation due to maltose must be calculated. On multiplying the number of grams of maltose in 100 c.c. of the solution by 2-78, the result is the angular rota- tion due to the maltose. Subtract this number from the observed angular rotation, and the remainder is the angular rotation due to dextrin. This angular rotation, on being divided by 4-01, gives the grams of dextrin in 100 c.c. of the liquid. From these data the percentage of dextrin and maltose in the original substance may be calculated. As an illustration of the polarimetric estimation of dextrin, the following ^ To prepare this, take 1 lb. of pulverised animal charcoal (bone charcoal) and boil with 2 quarts of commercial hydrochloric acid diluted with 1 gallon of water. Filter through calico, and wash with water till free from acid, dry and ignite to redness in a closed crucible. Store in a well-stoppered bottle. 814 THE TECHNOLOGY OF BREAD-MAKING. example of the analysis of a sample of wheat germ is given. A 10 per cent, solution of the substance was made with cold water, filtered, shaken up with animal charcoal, and again filtered until clear. The clear solution was weighed in a beaker, raised to 100° C. in the water bath, made up to original weight, and filtered from the coagulated albumin. The reading with the polarimeter was 2-00° to the right. A maltose estimation was made with 20 c.c. of the solution to 25 c.c. Fehling’s solution, and 50 c.c. of water. The resulting precipitate was in this instance converted by ignition into cupric oxide (CuO) and weighed as such, then — Wt. of CuO, 0-1515 X 0-7257 = 0-1099 gram of maltose in 20 c.c. of 10 per cent, solution. 0-1099 X 5 = 0-5495 gram of maltose in 100 c.c. 0-5495 X 10 = 5-495 per cent, of maltose in the substance. Then, 0-5495 x 2-78 = 1-52 = angular rotation due to maltose. Total angular rotation, 2 — 1-52 = 0-48 = angular rotation due to dextrin. ^ ^ j = 0-12 gram of dextrin in 100 c.c. 0-12 X 10 = 1-20 per cent, of dextrin in the substance. 876. Estimation of Starch. — ^This estimation may be roughly made by retaining for examination the whole of the washings from the gluten test for wheat or flour. For this purpose wash the dough in small quantities of water at a time until the water remains clear, the washings being poured into a large beaker. Stir the starch and water thoroughly together, and then strain through a piece of fine silk into a second clean beaker, in order to recover any fragments of gluten that may possibly have been in the first instance forced through the silk. Having washed the whole of the starch through the silk, stand the beaker aside, in order to allow the starch to subside. Counterpoise a pair of filters and arrange them in funnels one under the other, so that the lower receives the filtrate of the upper. Remove the lower funnel and pour the supernatant liquid from the starch on to the upper filter ; as soon as the filtrate runs clear, replace the second funnel and continue the filtration, finally rinsing the whole of the starch on to the filter ; wash with distilled water and dry, first for a few hours at 40° C., and afterwards in the hot-water oven. The reason for first drying at a low temperature is to prevent the gelatinisation of the starch ; this preliminary drying may generally be done on the top of the hot- water oven. The counterpoise filter may, of course, be dried direct in the oven, and at the end weighed against the starch and filter. The process of drying is much accelerated by giving the starch a final washing with 95 per cent, alcohol so as to remove the water. This treatment gives the weight of starch cells of the wheat or flour. These, it must be remembered, contain a certain quantity of starch cellulose. 877. Estimation of Soluble Starch by Conversion into Dextrin and Maltose. — -For more refined estimations the method of first converting the starch into dextrin and maltose, and then determining those bodies, is preferable. O’Sullivan gives, in the Journal of the Chemical Society for tlie year 1884, a description in detail of his method of making such esti- mations. The method is based on first removing dextrin, maltose, and other soluble bodies from the substance by the use of water and other solvents, tlien converting the starch into dextrin and maltose by the action tliereon of malt diastase, and then estimating the dextrin and maltose by Fehling’s solution and the polarimeter. The following special reagents are necessary : — 878. Alcohol. — This reagent is required absolutely free from water ESTIMATION OF CARBOHYDRATES. 815 and also mixed with water in different proportions. “ Absolute ’’ or water- free alcohol may either be purchased or prepared in tlie following manner : ■ — Take two quarts of the best methylated spirits, add thereto about half its weight of recently and thoroughly burnt quicklime, shake up vigorously two or three times a day for 3 or 4 days. The quicklime will de- hydrate the acohol, by combining with the water present, to form slaked lime (calcium hydroxide). The alcohol must next be separated from the lime by distillation. For this purpose arrange a glass flask in a large sauce- pan to be used as a water bath. Fit a cork with leading tube to the neck of the flask, and connect this up to a condensing worm, provided with a copious supply of water. Be sure that all joints are perfectly air tight. Fill the water bath with water, and make arrangements for securing the flask, so that, as it becomes lighter by the evaporation of the spirit, it shall not capsize. Pour off the clear alcohol from the lime into the flask. Intro- duce a few small sharp-pointed steel tacks : these will cause the liquid to boil without bumping. Then connect up the whole of the apparatus, and raise the bath to the boiling point by means of a bunsen. Collect the distilled spirit in a dry stoppered bottle. It must be remembered that alcohol is highly inflammable, and therefore every care must be taken to prevent an accident through fire. The lime used for the desiccation of the alcohol will still contain a considerable quantity of spirit ; this may in great part be recovered by pouring the whole on to stout calico and squeez- ing as much as possible of the spirit out. Dry potassium carbonate is perhaps frequently a more convenient agent for desiccating alcohol. The carbonate absorbs the water, and forms a heavy solution on which the alcohol floats. When distilling, both solu- tions may be poured into the still together, and distillation in a water bath •continued as long as anything comes over. The residual solution of potas- sium carbonate may then be evaporated to dryness in an ordinary iron saucepan, and used again for the same purpose. Absolute alcohol has a specific gravity of 0-7937 at 15° C. The per- centage of water is usually obtained by observing the specific gravity by means of a hydrometer. This is a glass instrument consisting of a weighted bulb and stem carrying a scale ; the hydrometer, on being placed in a liquid, floats higher or lower according to its density. The specific gravity of water is often reckoned, for convenience, at 1000 ; absolute .alcohol is then said to have a density of 793-7. A hydrometer should be procured from the instrument makers marked in single degrees from 750 to 1000. Cool down some of the distilled alcohol to 15° C., and pour out into a hydrometer jar. (This is a tall glass vessel in which the instrument can just float.) Introduce the hydrometer, and observe the density of the liquid ; should this be from 795 to 800, the alcohol may be considered for practical purposes absolute. Mixtures of alcohol and water of the following •densities are also required : — 820, 830, 860, 880, and 900 degrees. These may be prepared by adding water to methylated spirit. Methylated spirit has itself a density of about 820, and, when re- distilled, may be used when that strength is directed. The strength of .solutions of other degrees of specific gravity is given below. Specific Gravity at 15-5° C. 1-0000 Absolute Alcohol by volume, % 0-00 Specific Gravity, at 15-5° C. 0-8599 Absolute Alcohol, by volume, 81-44 0-9499 41-37 0-8299 91-20 0^9198 57-06 0-8209 93-77 0-8999 65-85 0-7999 98-82 ■0-8799 73-97 0-7938 100-00 816 THE TECHNOLOGY OE BREAD-MAKING. In order to obtain diluted spirits of the other gravities required, water may be added in the requisite proportion to methylated spirit. As alcohol and water, on being mixed, contract in volume [i.e., 50 c.c. of alcohol and 50 c.c. of water produce less than 100 c.c. of the mixture), the amount of water to be added to the methylated spirit to produce each degree of dilu- tion cannot be calculated with absolute exactness, but still sufficiently near for present purposes. Knowing that alcohol of sp. gr. of 820 contains 93-77 of alcohol and 6-23 of water, the quantity necessary to be added is determined by the following formula : — A = percentage of absolute alcohol in stronger spirit. a = ,, ,, ,, ,, weaker ,, W = water ,, stronger ,, w = ,, ,, ,, weaker ,, Q z= quantity of water to be ^dded to 100 c.c. of the lower sp. gr. spirit to produce the higher sp. gr. spirit. Then Q = ^ ^ _ W a From this formula it is found that to 100 c.c. of 820 spirit the following approximate quantities of water must be added to produce the spirits of correspondingly higher gravities : — sp. gr. 830, 3 c.c. ; 870, 21 c.c. ; 900, 43 c.c. 879. Diastase. — Take 2 or 3 kilograms (5 or 6 lbs.) of finely ground pale barley malt, add sufficient water to completely saturate it, and when saturated to slightly cover it. Allow this mixture to stand for 3 or 4 hours, and then squeeze as much as possible of the solution out by means of a filter press. Should the liquid not be bright, it must be filtered. To the clear bright solution, add alcohol of sp. gr. 830 as long as it forms a precipitate, and until the liquid becomes opalescent or milky. Wash this precipitate with alcohol of sp. gr. 860-880, and finally with absolute alcohol. Press the precipitate between folds of cloth, in order to dry it as much as. possible. Then place the precipitate in a dish, and keep under the exhausted receiver of an air-pump, together with a vessel containing concentrated sulphuric acid, until the weight becomes constant. The kind of air-pump known as a mercury sprengel pump is best fitted for this purpose. Prepared and dried in this manner, diastase is a white, easily soluble powder, retaining its activity for a considerable time. Store the substance in a dry stoppered bottle, and keep in a cool and dry place. 880. Method of Performing Analysis. — ^The analytic operation is per- formed in the following manner : — Weigh out accurately 5 grams of the finely ground meal or flour ; introduce this quantity into a wide-necked flask, with a capacity of 100 to 120 c.c. (a 4 ounce conical flask wdll be found most convenient). Add sufficient alcohol of sp. gr. 820 to just saturate the flour, and then 20 to 25 c.c. of ether. Cork the flask, and set aside for a few hours, shaking up occasionally. Decant the clear ethereal solution through a filter, wash the residue three or four times with fresh quantities of ether, pouring the washings each time on the filter. To the residue add 80 to 90 c.c. of alcohol of sp. gr. of 900 ; re-cork the flask, and maintain the mixture at a temperature of 35° to 38° C. for a few hours, shaking occasion- ally. When the alcohol solution has become clear, decant it through the filter used for filtering the ether solution, and wash the residue a few times with alcohol of the strength and temperature directed above. Wash the residue in the flask, and any that may be on the filter, into a beaker capable of holding 500 c.c., and nearly fill the beaker with water. In about 24 hours the supernatant liquid becomes clear, when gradually decant ESTIMATION OE CARBOHYDRATES. 817 through a filter. Wash the residue repeatedly with water at 35° to 38° C., and then transfer to 100 c.c. beaker. Take the filter from the funnel, open out the paper on a glass plate, and remove every particle by means of a camel-hair brush cut short, and a fine-spouted wash-bottle. Having thus transferred the whole of the residue, the beaker should not contain more than 40 to 45 c.c. of liquid. Boil for a few minutes in the water bath, care being taken to stir well in order to prevent “ balling,"’ or unequal gelatinisa- tion of the starch. After this, cool down the beaker still in the bath to 62° to 63° C., and add 0*025 to 0*035 gram of diastase dissolved in a few c.c. of water. In a few minutes the whole of the starch is dissolved, and a trace of the liquid gives no discolouration with iodine. Continue the digestion for about an hour, then raise the bath to the boiling point, and boil for 8 or 10 minutes. Pour the contents on to a filter, and receive the filtrate into a 100 c.c. measuring flask ; carefully wash the residue with small quantities at a time of boiling water. Cool the flask to 15*5° C., and make up its con- tents to 100 c.c. with distilled water. Should the washings and solution exceed 100 c.c., they must be evaporated down to that amount. Take a polarimetric reading of this solution in the 20 centimetre tube. Five c.c. of the solution is a convenient quantity to take for the estimation of maltose. This is rather a small quantity to measure accurately ; it may, if wished, be weighed instead, or 25 c.c. may be taken and diluted down to 100 c.c. with water ; 20 c.c. of the diluted solution may then be taken and added to 25 c.c. of Eehling’s solution and 50 c.c. of water. Proceed as before described with the estimations, and calculate the quantity of maltose from the weight of precipitated CU 2 O. Calculate the relative percentages of dextrin and maltose in the usual manner. Starch produces its own weight of dextrin and fff = 1*0546 its weight of maltose. To obtain the weight of starch from the dextrin and maltose it produces, the weight of the dextrin must be added to that of the maltose divided by 1*0526, or multiplied by 0*95. These calculations will be rendered clear by the study of the following example taken from O’Sullivan’s paper. In the analysis of a sample of white wheat, 4*94 grams were taken. The 100 c.c. solution had an optical activity equivalent to 8*52° for Sd, and contained 2*195 grams of maltose. 2*196 X 2*78 = 6*10°, angular rotation due to maltose. 8*52° — 6*10° = 2*42°, angular rotation due to dextrin. _ (). 0 Q 5 gram of dextrin in 100 c.c. Maltose, 2*196 == starch, 2*196 X 0*95 = 2*086 Dextrin, 0*605 = starch, 0*605 Total starch = 2*691 ^ = 54*47 per cent, of starch present. ^ 4*94 A duplicate analysis on 6*009 grams differed only by 0*03 per cent. In the absence of diastase, starch may usually be determined with sufficient accuracy for technical purposes in the following manner : — Remove by washing or otherwise all other carbohydrates, and gelatinise the starch by heating with water. From a known weight of the same variety of starch prepare a solution of approximately the same strength. Put 50c. c. of each in a separate flask, and add 50 c.c. of 10 per cent, sulphuric acid. Cork the two flasks, and stand in a hot-water bath until a drop on being taken out gives no reaction with iodine solution. Then neutralise by adding solid caustic potash in small fragments, until the solution gives A faintly alkaline reaction to litmus paper ; and precipitate from 10 to 25 c.c. of the solution, according to strength, with Fehling’s solution. Knowing 3 G 818 THE TECHNOLOGY OP BREAD-MAKING. by the test with pure starch what weight of CuaO it precipitates under these conditions, the quantity of starch in the substance being tested can be readily calculated. 881. Estimation of Dextrin and Soluble Starch. — It occasionally becomes^ necessary to estimate dextrin in the presence of soluble starch, as, for in- stance, in bread soluble extracts. The following method may then be adopted ; — Take 20 c.c. of the soluble extract and add to 250 c.c. of redis- tilled spirits ; if the precipitate is very little, take double the quantities filter and proceed with the estimation precisely as previously directed for dextrin. Control the results by determining proteins in the dried and weighed precipitate — the residue is a mixture of dextrin and starch. Proceed to estimate the starch in the following manner : — Prepare first of all the following reagents — 0-5 per cent, solution of wheat starch. 5 per cent, solution of sulphuric acid. Solution of iodine in potassium iodide of sherry tint. Take two graduated Nessler glasses, and add to each OT c.c. each of iodine solution and sulphuric acid ; make up to 50 c.c. with distilled water. To one add 0-5 c.c. of starch solution and stir ; to the other add the diluted soluble extract from a burette until there is the same depth of blue tint in each. The solution to be tested is conveniently of approximately the same strength as the standard starch solution. If this first test shows it to be too concentrated, dilute, and repeat the estimation. Having read off the solu- tion necessary to match the 0*5 c.c. of standard starch, add another 0-5 c.c. to the standard in the Nessler glass, and again run in the extract solution until the colours are of equal depth of tint. Take the reading, and add another 0-5 c.c., and repeat the titration. In this way three separate read- ings are obtained, which should closely agree. The following are results, obtained in an actual analysis : — standard Starch Solution. 0*5 c.c. 1-0 „ 1-5 „ 3*0 „ Diluted Bread Extract. 0*30 c.c. 0-55 „ 0-85 „ 1*50 „ The whole of these come very closely together, and it was assumed that 1-5 c.c. of the bread extract contained as much starch as 3-0 c.c. of the standard starch solution. To ensure success with this method of starch estimation the solutions must be dilute, and there should be no other colour-producing body than starch present. The iodine must not be in large excess, but must give a pure blue colour with starch : too much produces a dirty greenish blue. But the iodine must be in excess of the starch present. To ascertain this by trial, after a titration, add a few drops more starch and the colour should darken. Both tests must be made up with precisely the same quantity of each reagent. Having determined the starch in this manner, deduct the amount from the total of starch and dextrin precipitated by alcohol ; the difference is dextrin. 882. Estimation of Cellulose. — ^The student already knows that cellu- lose has the same chemical composition as starch, but that it differs from that body in being insoluble in boiling water. The cellulose or woody fibre of grain has been estimated at about 10 per cent, of the whole : but of this much is soluble in the digestive secretions of animals, particularly those which ruminate, therefore an estimation of cellulose simply is not the one ESTIMATION OF CARBOHYDRATES. 819 most valuable to tlie cliemist whose investigation is made for the purpose of determining the food value of a substance. What for this purpose should be ascertained is that percentage of the grain or flour which is ejected from the alimentary canal in an unaltered condition. A process is therefore selected whicli is somewliat similar to the digestive action which proceeds in the stomach, this action being imitated by alternate treatment with dilute acid and alkali. 883. Special Reagents Necessary. — ^The first of these is a 5 per cent, solu- tion of sulphuric acid. In a small beaker weigh out 100 grams of the con- centrated acid, and make up to 2 litres. In the next place prepare a 12 per cent, solution of caustic potash by weighing out 240 grams of the pure dry sticks, dissolving, and making up to 2 litres Avith water. It is im- portant that 20 c.c. of the acid solution should be approximately neutralised by 10 c.c. of the alkali. 884. Mode of Analysis. — -Take 5 grams of the meal or flour, and mix them thoroughly with 150 c.c. of water in a beaker. Stand this in a hot- water bath, and raise to a boiling heat in order to effect the gelatinisation of the starch ; stir frequently with a glass rod ; add 50 c.c. of a 5 per cent, solution of sulphuric acid, and continue the boiling for an hour, stirring occasionally, and maintaining the volume at 200 c.c. by adding from time to time a little water. (The proper volume should be indicated by a mark made with the diamond on the outside of the beaker.) The acid Avill by this time have converted the starch into sugar. To this solution next add 50 c.c. of the solution of caustic potash ; this quantity will neutralise the free acid, forming potassium sulphate, and will leave an excess of alkali in the solution approximately equivalent to the amount of acid first used. Again boil in hot -water bath for an hour, adding water to supply that lost by evaporation, and occasionally stirring. At the end of this time, dilute with cold water, stir, and allow the residue to subside. Wash by decanta- tion, using large quantities of tap water (provided it is absolutely free from sediment), pouring as little as possible of the residue on to the paper. Stout, well-made quantitative Alters of about 8 or 10 inches diameter should be employed. Next transfer the residue to the filter, and wash once with dilute hydrochloric acid, in order to dissolve any calcium carbonate that may be precipitated from ordinary AA^ater by the potash. Then AA'ash AAuth distilled AA^ater till free from acid, and alloA\^ the Alter to drain. While still AA^et, remove the filter paper from the funnel, carefully spread it out flat on a sheet of glass, and AAuth a AA'ash bottle and short camel-hair brush, transfer the Avhole of the residue to a counterpoised glass dish ; dry in the hot-AA'ater oven and Aveigh. The dry residue multiplied by 20 gives the percentage of indigestible fibre in the sample. 885. Glycerin Method of Cellulose Estimation. — ^A method of estimating crude fibre has been devised by Honig, based on the fact that protein and starch become soluble in AA'ater after heating AA'ith glycerin to 210° C., at AA'hich temperature cellulose is not attacked. The folloAA'ing is a modifica- tion of this method, proposed by Gabiel, in order to provide for the solu- tion of certain substances, both nitrogenous and non-nitrogenous, other than cellulose which are unattacked by glycerin alone : — A solution of caustic alkali in glycerin is prepared by dissolving 33 grams of caustic potash in glycerin, and making up to 1 litre. For making the analysis, 2 grams of the substance are heated in a 250 c.c. flask on a piece of AA'ire gauze over a naked flame, AAuth 60 c.c. of the potash-glycerin. At about 130° C. a vigorous reaction occurs, and care must be taken that none of the solution is lost by foaming. At a temperature of 160° C. the reaction is for the most part 820 THE TECHNOLOGY OE BREAD-MAKING. finished, after which the temperature is raised to 180° C. The mixture is then poured into 200 c.c. of boiling water, weU stirred, allowed to settle, and the supernatant liquid removed by upward filtration through a funnel having a piece of linen tied over the end. (The material known as swansdown answers well for such filters.) The residue is again boiled with 200 c.c. of water, allowed to settle and filtered, and a third time with the same quantity of water to which 5 c.c. of 25 per cent, hydrochloric acid have been added. The residual fibre is washed with alcohol and ether and dried. The extremely small quantity of nitrogenous substances left in the crude fibre appears to be in most cases negligible. The centrifugal separator has been called into requisition for fibre esti- mations. This machine consists of a wheel making some 3000 or 4000 revolutions per minute, on the circumference of which vessels are attached ; the centrifugal action acts like gravitation, only with far more intensity in separating bodies whose specific gravity is different. The quantity of material taken for analysis is 1 gram ; in event of this containing any con- siderable quantity of fat, it is first shaken up with 20 c.c. of ether in a proper tube, and subsequently rotated in the machine. The supernatant ether is poured off, and the substance subjected twice more to the same operation with ether, being each time shaken up, and then treated in the centrifugal. The ether is driven off the residue by heating in the water bath, 30 c.c. of hot water added, and the heating continued for about 10 minutes, the contents of the tube being stirred with a glass rod flattened at the end. Next, 10 c.c. of 5 per cent, (by volume) sulphuric acid are added, and the heating and stirring continued for another 30 minutes. The tube is now rotated in the separator, at a speed of at least 2000 revolutions per minute, for about 3 or 4 minutes. Most of the insoluble matter is separated in a com- pact form on the bottom of the tube ; the turbid liquid is poured off on to a weighed or counterpoised filter sufficiently large to hold the contents of the tube. The tube is then refilled with 40 c.c. of hot water, stirred re- peatedly during a period of from 10 to 15 minutes, the tube being meanwhile suspended in the water bath. The tube is again rotated, the clear liquid poured off on the filter, and the washing repeated in the same way. The residue is next treated with 30 c.c. of hot water, and 10 c.c. of a 5 per cent, solution of caustic potash, heated in the water bath, and stirred repeatedly during 30 minutes. The tube is placed in the separator, and the residue washed in the same way as after the acid treatment. The fibre is next thrown on to the filter, washed in succession with alcohol and ether, and dried and weighed in the usual manner. Analysis of Bodies containing Carbohydrates. 886. Malt. — ^It is comparatively rarely that for bakers’ purposes an analysis or assay of malt is required. The principal point is the character and amount of extract it affords on being mashed ; to this reference has already been made in Chapter XII., paragraph 398. A miniature mash of the same proportions may be made in the following manner : — Finely grind tlie sample of malt, mix thoroughly, and weigh out 158 grams ; mix with about 900 c.c. of warm water, and place in a water bath maintained at a temperature of 60° C. Let it remain until a drop taken out after stirring gives no starch or amylodextrin reaction with iodine. Then raise to the boiling point, cool, and transfer the whole to a litre flask ; make up to tlie mark with distilled water ; pour out into a larger flask or beaker, and add another 50 c.c. of water. Thoroughly mix, allow to settle, and take the density of the supernatant liquid, at a temperature of 15-5° C., by means of the hydrometer. The quantities taken are equivalent to 40 gallons of wort from 63 lbs. of malt : the extra 50 c.c. are allowed in order to provide ESTIMATION OF CARBOHYDRATES. 821 for the average amount of “ grains ” resulting from this quantity of malt. There are thus 1000 c.c. of wort from 158 grams of malt. The percentage of solid extract yielded by the malt is readily calculated. Thus, supposing in a test the hydrometer density is 1035, then : — (1035 - 1000) X 10 3-85 = 90-9 grams of solid extract in 1000 c.c. of wort. As 158 : 100 : : 90-9 = 57-53 per cent, of solid extract. The whole of the constants in the above may be reduced to one single factor, 1-644, and we then have (1035 — 1000) X 1-644 = 57-54 per cent, of solid extract. For a detailed description of the method for an exhaustive assay of malt, the reader is referred to Moritz and Morris' Science of Brewing, pages 452 et seq. 887. Malt Extracts. — 'The following determinations should be made in analysing extracts of malt and similar preparations : — Reducing sugars, cane sugar, dextrin, proteins, water, phosphoric acid (P 2 O 5 ), other mineral matter, specific rotatory power, and diastatic , capacity by Lintner, or other methods hereinafter described. A 10 per cent, solution of the substance should first be prepared, which, either with or without dilution, may be employed for the following estimations. Reducing Sugars. — Take 2 c.c. of 10 per cent, solution, and precipitate as usual with Fehling’s solution (30 c.c.). Cane Sugar. — This is conveniently determined by O'Sullivan's method. Take 20 c.c. of 10 per cent, solution, make up to 100 c.c., raise to 55° C., and add 0-2 grams of solid brewers' yeast (prepared by drying the liquid yeast on a towel), or compressed distillers' yeast free from starch, digest in a constant temperature water bath at 55° C. for 4 hours, make up loss by evaporation (or conduct the operation in a tightly corked flask), filter, and determine reducing sugars in 10 c.c. by Fehling's solution. The difference in weight of CU 2 O obtained in this and the preceding determina- tion is CU 2 O reduced by the glucose from cane sugar, and is readily calcu- lated into the percentage of that body. Dextrin. — Take 20 c.c. of 5 per cent, solution, add to 250 c.c. of spirit, and proceed as described under Estimation of Dextrin, paragraph 866 . Should the amount of precipitate be very small, recommence the estimation, using the 10 per cent, solution. Determine proteins by KjeldahTs process in the dried and weighed precipitate ; deduct from the weight of precipitate, and calculate as dextrin. Proteins. — Determine direct by Kjeldahl's process on 1-0 gram of the extract. Water. — Take 5 grams of extract, dry till weight is constant in a plati- num basin ; about 36 hours are necessary at 100 ° C. When speed is an object, either a smaller quantity ( 1-0 gram) may be used, or an oven at 110° C. employed. Or preferably a vacuum drying oven may be used, in which case the drying may be conducted at a temperature below 100 ° C. Ash. — Ignite the dried residue from 5-0 grams (residuum from water estimation) until a white ash is obtained. Note, the extract sometimes swells up enormously as it carbonises ; in such cases allow to cool, and break down the carbonaceous mass so that it lies easily in the dish. (This should be done on a sheet of glazed paper.) Phosphoric Acid. — Dissolve the ash in dilute nitric acid (1 to 3), and proceed with estimation by molybdate and “ magnesia mixture " (see paragraph 820). The ash, less phosphoric acid, gives “other mineral matter." 822 THE TECHNOLOGY OF BREAD-MAKING. Specific Rotatory Power. — Make up a 20 per cent, solution of the extract, and take a polarimetric reading precisely as described in paragraph 875 on Polarimetric Determination of Dextrin and Maltose. Calculate out the specific rotatory power both on the whole and the dried extract : or, if preferred, the rotatory power per gram of either whole or dried extract may be calculated. For the whole extract, with a 20 per cent, solution, this is the total angular rotation. Supposing in the case of an extract the total solid matter to be 80 per cent., and the observed rotation 32-4°, then 32-4 = 1-62° rotatory power per gram of whole extract ; ^ and ^ ^ = 2-02° rotatory power per gram of dried extract. ■' 80 The specific rotatory power may be obtained by multiplying by 50 in each case. Calculation of Results — The reducing sugar of pure malt extracts, ob- tained by concentrating the wort produced by total conversion of the whole malt, consists principally of maltose On calculating it as such, and adding together the results of the whole of the determinations given, there is usually an excess of about 5, or more, per cent, over 100 : this is due to some of the reducing sugar being glucose instead of maltose. On the other hand, cold water extracts of malt contain only the pre-existent sugars of malt, con- siderable proportions of which are glucose : these, if worked out as maltose, give far too high a result, while if calculated as glucose, the result is too low. Again the explanation is that in addition to glucoses there is maltose also present. It is frequently convenient to be able to esti- mate approximately the relative proportions of glucoses and maltose, and this may be done in the manner to be now described. It should first, however, be mentioned that doubtless malt extracts contain certain sub- stances which escape determination in all the estimations previously given ; but these cannot in any case represent a large percentage of the whole, and for present purposes may be neglected, the reservation being made that a small part of the percentage returned as sugar may consist of indeterminate bodies. Assuming that 100, less the cane sugar, dextrin, proteins, water, and ash, consists of reducing sugars, then we have Total reducing sugar by difference in 100 grams extract = S. Weight of cuprous oxide precipitated by 100 grams extract = W. ,, maltose in 100 grams = m. „ glucose „ =g. ,, cuprous oxide precipitated by I gram of maltose = 1-238 grams. ,, cuprous oxide precipitated by I gram of glucose = 1-983 grams. Then, m + ^ = S : (Equation No. I.) and 1-238 m + 1-983 g —W . (Equation No. 2.) From these the values of m and g may be determined thus : — Multiplying equation No. I by 1-983, and subtracting No. 2 from the product, we get 1-983 m + 1-983 g = 1-983 S less 1-238 m + 1-983 = W 0-745 m — 1-983 S — W . 1-983 S-W “ = 0 ^ 4 ^ In the same way ~ - 0-745 or more simply, g = ^ — m. ESTIMATION OF CARBOHYDRATES. 823 The following figures were obtained in the analysis of a sample of malt extract : — S = 60-5. W 80. (1-983 X 60*5) - 80 S — m = g, therefore 60-5 — 53-65 = 6-85. The percentages of maltose and glucose are therefore respectively 53-65 and 6-85. In pure malt extracts obtained by concentration of the wort of the entire malt, so mashed as to ensure the hydrolysis of the whole of the starch, the percentage of glucose should not exceed from y to ^ that of maltose. W ith highly diastatic extracts containing also a high percentage of proteins, the proportion of glucose is as a rule considerably greater. On comparing the results thus obtained with the specific rotatory power of the sample, it will be found that the glucose is almost entirely of the dextrose or right- handed variety. The other calculations require no detailed explanation. 888. Diastatic Capacity on Lintner’s Scale. — ^For brewing purposes diastatic capacity is now almost invariably determined by Lintner’s method, and the result expressed on Lintner’s standard, or in “ degrees Lintner.” That standard is : — “ The diastatic capacity of a malt is to be regarded as 100, when 0-1 c.c. of a 5 per cent, solution reduces 5 c.c. of Eehling’s solu- tion.” For the determination, “ soluble starch ” and standard Fehling’s solu- tion are required. The soluble starch must be prepared according to the method described in Chapter VI., page 81. The digestion with acid must be allowed to proceed fully as long as directed, as, unless the starch is ren- dered thoroughly soluble, it naturally gives apparently low diastatic results. It is well during its preparation to test a small portion at the end of 7 days by thoroughly washing, and then dissolving in boiling water : the solu- tion must be absolutely clear and limpid. When about to make an estima- tion, take 2-2 grams of the soluble starch and dissolve in hot water, cool, and make up to 110 c.c. If testing a malt or flour, take 25 grams (of course, finely ground) and digest with 500 c.c. at ordinary temperatures for 5 hours. Filter until perfectly bright. Arrange ten test tubes in a stand, and add to each 10 c.c. of the soluble starch solution. Then to the first, add 0-1 c.c. of the malt or flour filtrate, to the second 0-2 c.c., and so on until the last receives 1-0 c.c. Shake them thoroughly, and allow the whole to stand for 1 hour in a water bath maintained at the constant temperature of 70° F. During this time the diastase wiU have converted more or less starch, accord- ing to its strength. Next add 5 c.c. of Fehling’s solution to each of the tubes, shake up, and place the whole series in boiling water for 10 minutes. Allow the precipitate to subside, and note the condition of the tubes ; in some the blue colour will probably have entirely disappeared, showing them to be over reduced, while others will still be more or less blue. Select the two tubes lying together in which one is slightly over and the other slightly under reduced. The number of c.c. required to give exact reduc- tion will lie between these, and should be judged according to which it appears the nearest. Thus, suppose as nearly as possible it is exactly mid- way between Nos. 5 and 6 , then the quantity of malt solution may be taken as 0-55 ; while if No. 5 is full yellow, while No. 6 is only very faintly blue, then one would give the quantity as 0-58 or 0-59, according to how near in one’s judgment it appeared to be to the 0-6. With a little practice .one soon gets able to judge very closely this second decimal. If the result of a test 824 THE TECHNOLOGY OF BREAD-MAKING. gives 0-5 c.c. as the quantity of malt solution required, then the sample is evidently only one -fifth of the standard strength of 100, or ^ ~ Lintner as diastatic capacity. But there is a certain amount of reducing sugar extracted from malt by cold water, and this also helps to reduce the Fehhng’s solution. The amount of this is determined in the following manner : — Take 5 c.c. of Feh- ling’s solution, 10 c.c. of starch solution, and 10 c.c. of water, and raise to the boiling point in a small flask. To this add the malt solution from a burette until the Fehling is exactly reduced ; then determine the apparent diastatic capacity of this solution. Supposing that 7 c.c. have been run in in order to reduce the Fehling, then 0 1 X 100 _ correction for reducing sugars extracted from the malt. For malts the correction 1-4 may usually be taken as a constant, and the above results become 20 - 1-4 = 16-8° Lintner. Working with malt extracts, the value of the correction becomes much higher, and must be determined for each individual sample analysed, and preferably before the diastase estimation. Take a 5 per cent, solution of the extract, boil, make up to original volume, filter, and titrate on Fehhng and starch as above described. In an actual analysis 1-25 c.c. of the 5 per cent, solution were required ; the correction therefore becomes 0*1 X 100 1-25 = 8*0° correction for reducing sugars present. From this it will be seen that the tenth tube in the diastase determination is nearly reduced by the sugars present alone. The diastase estimation should now be made : this in the sample in question amounted to 0-73 c.c. ; then ^ ^0^3^^^ ~ 13-7° apparent diastatic capacity. 13*7 — 8-0 = 5-7° Lintner, real diastatic capacity. In malt extracts and other diastatic preparations the diastatic capacity varies very widely, and either none or all of the series may be completely reduced. In the former case the diastatic capacity must be less than 10 minus the correction. Make another diastase estimation with a 25 per cent, solution of the extract, and multiply the correction by 5 ; the solution being of 5 times strength, the net figure thus obtained for real diastatic capacity must be divided by 5 in order to give degrees Lintner. Should there be no reduction in any of the tubes, the diastatic capacity must be less than 2 minus the correction, which practically amounts to its total absence. On the other hand, the whole of the series may be reduced, showing that the diastatic capacity is more than 100 minus the correction. In this case make up a 0-625 per cent, solution, and use it for a diastase estimation ; multiply the result by 8, and take the correction as | that with the 5 per cent, solution. The following is the result of an estimation on a diastase preparation made by the authors ; — Correction for reducing sugars on 5 per cent, solution = 8-2°. All tubes were reduced. With 0*625 per cent, solution, reduction effected by 0*42 c.c. ^ = 190*5° apparent diastatic capacity. ESTIMATION OE CARBOHYDRATES. 825 190-5 — = 189-48° Lintner, real diastatic capacity. The three diastase tests made in this manner give a total range of from 2° to 800° Lintner, and with each test overlapping the other. In comparing extracts for bread-making purposes, it is sometimes advisable to also test on starch paste ; in that case proceed exactly as with soluble starch, except that ordinary starch is substituted and carefully gelatinised without ‘‘ balling.” 889. Diastase Tests on Flours. — ^These may be made by taking a given quantity of the extract, mixing with flour and water, and digesting for a given time at some fixed temperature. The amount of matter dissolved and maltose produced may then be determined by direct estimations. Full particulars of such determinations are given in paragraph 890. Baking tests afford the most valuable means of testing diastatic value of extracts for bakers. These tests should be made as directed in Chapter XXVI., paragraph 810, with the extract added to the water. It is well to take the uniform quantity of the extract equivalent to 1 lb. to the sack, 2 grams = 20 c.c. of a 10 per cent, solution (the quantity of water used for dough-making must, of course, be diminished by the 20 c.c. taken with the extract). Prepare 100 c.c. of the 10 per-cent, solution, place half of it in a flask, weigh, boil for 5 minutes, and make up to the original weight with water, and call this No. 2. Prepare duplicate loaves, using the No. 1 or unheated extract solution in the first, and No. 2 or boiled solution in the second. Make up also a plain loaf. No. 3, with the same flour ; compare carefully the character of the three for volume, colour, pile, moistness, flavour, and any other points of interest to the baker. No. 2 will have had its diastase killed, and will contain only such maltose and other bodies as are contained in the extract ; No. 1 will contain in addition all such sub- stances as have been produced by the diastatic action of the extract itself. If wished, determinations may be made of soluble extract and maltose in each of the loaves. The results may then be returned as shown in blank below : — Soluble Extract. Maltose. Normal Quantities in Plain Bread, deter- mined in No. 3 . . . . Quantities added in Extract, being difference between Nos. 2 and 3 . . ...... Quantities produced by Diastatic Action, being difference between Nos. 1 and 2 Total . . . . In this way any extract can at once be valued both for added and pro- duced maltose and other substances. 890. Experimental Comparison of Diastase Determinations. — ^In order to institute a comparison between results obtained by Lintner’s method and the amount of change produced both in flour digestion and ordinary baking, the following experiments were made : — Lintner’ s Determinations. — First, four extracts were selected, one of which (No. I.) had, according to Lintner, a low diastatic value ; another (No. II.) was remarkably high ; while the third gave practically no read- ing on Lintner ’s scale. The fourth was another sample from the same source as No. I., but from a more active malt, and manufactured at a lower temperature. The results are in each case tabulated. 826 THE TECHNOLOGY OF BREAD-MAKING. No. I. Extract, Diastatic Capacity .. 1-2° Lintner. No. II. „ „ . . 354° No. III. „ „ . . 0-8° No. IV. ,, ,, not accurately determined, but slightly higher than No. I. Another sample of No. II., same type, gave 320° Lintner on being tested. Duplicates of Nos. I. and III. were in absolute agreement with those quoted. Flour Digestion Tests . — A 0-5 per cent, solution was prepared of each extract ; a half of this was raised to the point of actual ebullition, cooled, and loss of weight made up with distilled water. The first part is called “ Active Extract,’’ and the second “ Killed Extract.” Of each, 100 c.c. ( = 0*5 gram extract) was taken, added to 25 grams of flour in a corked flask, shaken vigorously, and all digested together for 4 hours in a water bath at 140-150° F. A blank experiment was also made with 100 c.c. water and 25 grams of flour only. The contents of the flasks were filtered, and “ soluble extract ” and maltose determined in the clear filtrate. The following are the results, expressed in percentages of the flour used. Soluble Extract and Maltose. • Percentage of Extract, less Total Solids in Malt Percentage of Soluble Extract on Flour used. Percentage of Extract and Percentage No. of Extract. Extract, less Total Solids in Malt of Extract with Plain Flour and Water = Extract =1-6 l-6+24-4=26-0, being Extract due to Diastatic Action. I. Active 26-28 24-68 0-28 I. Killed 24-60 23-00 Minus quantity. II. Active 48-04 46-44 22-04 II. Killed 37-32 35-72 11-32 III. Active 31-52 29-92 5-52 I III. Killed 27-08 25-48 1-08 IV Active 34-52 32-92 8-52 IV. Killed 28-76 27-16 2-76 V. Flour and Water only 24-40 — — Percentage of Maltose Percentage of Maltose. Percentage of Maltose, less that in added Malt Extract, say 1-2. less that in Malt Ex- tract and that resulting from Flour only = l-2-l-8-88=10-08, being Maltose due to Diastatic Action. I. x^ctive 23-75 22-55 12-47 I. Killed 14-54 13-34 3-26 II. Active 36-83 35-63 25-55 1 II. Killed 25-52 24-32 14-24 III. iVctive 19-06 17-86 7-78 III. Killed 14-86 13-66 3-58 IV. xWtive 22-61 21-41 11-33 IV. Killed 17-12 15-92 5-84 V. Flour and Water only i 8-88 8-88 Baking Tests . — Baking tests were then made with the first three extracts, the method being that described in the preceding paragraph, except that tlie “ killed ” solutions were sim]fly raised to actual ebullition, without con- tinuing the boiling for the 5 minutes as there directed. The quantity of ESTIMATION OF CARBOHYDRATES. 827 ■extract in each case was equivalent to 1 lb. to the sack of flour. The follow- ing are the results of various determinations made on the baked loaves : — Analyses of Baked Loaves. No. of Extract. Water. Soluble Extract. Maltose. Dextrin. I. Active. . 43-81 6-12 5-41 3-25 I. Killed 42-24 5-62 3-31 2-75 II. Active. . 41-71 9-22 6-22 4-90 II. Killed 42-90 5-90 3-64 2-90 III. Active. . 42-21 5-04 4-70 2-45 III. Killed 42-74 4-94 3-79 2-45 V. Plain Loaf 42-25 4-74 3-15 2-40 From these data the amount of each constituent may be calculated into quantity present in plam loaf, that added in “ killed ” extract, and that produced by diastatic action. When thus treated the results assume the following form : — Source of Each Constituent in Baked Loaves. Constituent and No. of Extract. Normal Plain Bread. Quantity due to “ Killed” Extract. Quantity due to Diastatic Action. Total Quantity. 1 1 4-74 0-88 0-50 6-12 Soluble Extract \ II 4-74 1-16 3-32 9-22 1 . Ill 4-74 0-20 0-10 5-04 I r I 3-15 0-16 2-10 5-41 Maltose . . . II 3-15 0-49 2-58 6-22 1 Im 3-15 0-64 0-91 4-70 1 ri 2-40 0-35 0-50 3-25 Dextrin . . . II 2-40 0-50 2-00 4-90 1 Ill 2-40 0-05 0-00 2-45 Reviewing these results, the following is noticed in the flour digestions : — No. I. extract, both active and killed, gave abnormally low soluble extracts, while No. I. active yielded an exceptionally high maltose result. There were no duplicates made of these, but the results of determinations in the baked loaves are in absolute agreement with them ; thus, in the digested flour the maltose is 0-90 of the total soluble extract, while the maltose in the bread is 0-88 of the soluble extract obtained. In each case except No. I. the killed extract still exhibited considerable amylolytic activity. Turning to the bread results, the water was determined as a check on the constitution of the loaves, and not as a measure of the yielding power of the flour. There is in the case of each constituent a greater quantity present in “ killed extract treated loaves than in that which was perfectly plain, a quantity partly, but not entirely, due to the actual matter intro- duced by the extract itself (a lb. of extract per sack equals approximately 0-25 per cent, on the baked bread). This shows that malt extracts contain a hydrolysing constituent, the activity of which is not destroyed by momen- tary boiling. In each case, and with each constituent estimated, except dextrin in No, III., there is an increase due to amylolytic action. In No. II., 828 THE TECHNOLOGY OF BREAD-MAKING. which gave by far the highest result on Lintner’s scale, there is also the highest amount of change in the baked loaf, but in nothing like the same proportion. The dextrins are obtained by precipitation with alcohol, but are not corrected for proteins. The reducing sugars are throughout reckoned as maltose : but the sum of the maltose and uncorrected dextrin is uniformly in excess of the total soluble extract. No specific researches have been made, but the probable cause is that some of the sugar is "glucose. 891. Adulterations of Malt Extract.— Malt extract may be adulterated either with molasses (treacle) or glucose syrups. The former of these may be detected by the large increase in the quantity of cane sugar present, as molasses contains from 35 to 48 per cent, of sucrose. It also usually con- tains considerable amounts of glucose. The so-called sirupy “ glucoses contain, when conversion has been arrested at the minimum point, large quantities of dextrin and maltose, and therefore in that particular closely resemble malt extracts. Commercial “ glucose ’’ is, however, practically devoid of protein constituents, and in this way is detected when used as an adulterant of malt extract. A polar imetric reading affords a valuable indication as to the purity of malt extracts. The following table gives the result of a number of such readings calculated to angular rotation per gram of undried substance in 100 c.c., the observations being made in a 2 deci- metre tube. POLAKIMETRIC ESTIMATIONS ON MaLT EXTRACT, ETC. No. 1. Malt Extract of known purity, tested March, 1893 2. Same make of Extract, sample taken April, 1893 3. Sample of suspected Malt Extract, very light in colour 4. Second sample of suspected Malt Extract 5. Lyle’s Golden Syrup, obtained personally by author . 6. No. 1 Syrup, lightest colour 7. No. 2 ,, intermediate 8. No. 3 ,, darkest 9. “ Glucose ” Syrup (White Confectioners’ 10. Mixture made personally by authors — No. 1, 7*07 grams ) From same 1 manufacturers No. 6, 4*79 1 ^' 11 . Calculated Rotatory Power from quantities taken Mixture made personally by authors — • No. 1, 7*07 grams ) No. 9, 6-26 „ I Calculated Rotatory Power from quantities taken Rotatory Power per Gram. . 1-59° . 1-52° 1-99° 1-79° 0- 52° 1- 05° 0-81° 0*52° 2- 30° 1-33° 1-33° 1-85° 1-89° Both the suspected samples had abnormally high rotatory powers, and were probably adulterated with ‘‘ glucose ” syrup ; they agree approxi- mately with No. 11. For comparison with the rotatory powers of the pure substances refer to paragraph 874. 892. Baking Powders, Analysis of. — ^Crampton, in a U.S. Department of Agriculture Bulletin, gives a detailed method of analysis of these, of wliich the following is a modification. In examining Baking Powders, a qualitative analysis serves to recognise whether the acid constituent is tartaric, phosphoric, or sulphuric acid, or a mixture of two or more of these. Tlie alkalinity of the aqueous solution should be tested as a guide to the amount of excess of carbonate employed. The following are among some of the more important estimations which should be made : — (1) Carbon Dioxide . — This is the measure of the essential strength of ESTIMATION OE CARBOHYDRATES. 829 the powder, as its value depends on the quantity of this gas liberated by the powder when used. Usually the total and available carbon dioxide are both measured, as, through deficiency in acid ingredients, the whole of the carbonates are not always decomposed when the powder is employed for baking purposes. The total carbon dioxide is obtained by treatment with excess of acid ; the available, by adding water and heating in as nea-rly as possible the same manner as in actual baking. Many of the recognised forms of apparatus for the measurement of carbon dioxide may be used for this purpose. Thus, the well-known Schroedter may be employed, in Avhich the liberating acid and drying tubes, etc., are all self-contained within the same apparatus, together with the powder, which is weighed before and after the acid and powder act on each other. The loss of weight is the measure of the amount of carbon dioxide evolved. In using an apparatus of this form, from I to 2 grams of the l^owder is weighed out and transferred to the flask of the Schroedter, previ- ously charged with dilute liberating sulphuric acid, and concentrated acid for drying the escaping gas ; weigh the whole apparatus, and allow the acid to enter very slowly. Toward the close of the reaction heat very care- fully, and add the acid finally to powder when hot. Care must be taken that, owing to the gelatinisation of the starch, the whole mass does not boil over, and thus vitiate the determination. Finally draw air through in the usual manner, and weigh with the ordinary precautions. Water must not be added to the powder before the reaction is started. To estimate avail- able carbon dioxide proceed in the same manner, except that distilled water must be used for liberating purposes, instead of dilute acid. Add the water slowly, and at the close bring it as nearly as possible to the boiling point, and maintain it at that temperature for 15 minutes, gently agitating the apparatus occasionally. For technical purposes, the carbon dioxide can be estimated with suffi- cient 'accuracy by a modification of the yeast apparatus described on page 199, the gas being measured volumetrically. It may be mentioned that I gram of sodium bicarbonate, NaHCOs, yields on treatment with excess'of acid 0-524 gram of carbon dioxide, being 267 cubic centimetres at 0° C., or 286 at 20° C. Further, 286 c.c. = 17-4 cubic inches. Take a 6 ounce flask and fit it with a good india-rubber cork, pass through the latter a right-angled delivery tube, and also a thistle funnel, provided with bulb of about 50 c‘.c. capacity, and a glass stopcock. Arrange the flask on a piece of wire gauze on the retort stand, and connect it up by means of a short length of india-rubber tubing to the end, c, of the T -piece. Fig. 21. Stand the gas collecting jar, /, in a deep vessel of cold solution of calcium chloride, sp. gr. 1-4, preferably using for this purpose a cylinder of glass. Weigh out 25 grams of the baking powder and place it in the flask, connect up the apparatus and exhaust the air until the liquid stands at zero in the glass jar. Fill the bulb of the thistle funnel with 10 per cent, sulphuric acid, turn the stopcock very gently, so as to allow the acid to enter drop by drop. Great care must be exercised in opening this stop- cock, as otherwise the column of water in the gas jar will draw the whole of the acid out of the funnel, and allow the apparatus to completely fill with air. W hen the reaction is over, gently heat the flask until the whole of the carbon dioxide is set free. Allow’^ the apparatus to cool, and read off the volume of carbon dioxide liberated. Make a deduction for the volume of acid which has been let in from the funnel ; this is easily done by measuring once for all the amount it delivers. If results are immediately w'anted, the apparatus may be cooled by pouring a little w^ater over it. To determine available carbon dioxide proceed in exactly the same w'ay, except that w^ater must be used instead of acid in the funnel, and gentle boiling should be 830 THE TECHNOLOGY OE BREAD-MAKING. employed at the termination of the reaction for about 15 minutes. Precisely the same remarks apply to the limits of accuracy of these tests^ as are made on the use of the apparatus for yeast testing in paragraphs^ 364-5. (2) Phosphoric Acid. — Weigh about 0-5 gram, ignite carefully, treat with nitric acid, dilute and filter. Precipitate with ammonium molyb- date, digest, filter, and wash with dilute nitric acid or ammonium nitrate solution. Dissolve the precipitate in ammonia, precipitate with magnesia mixture, filter, wash with dilute ammonia, ignite, and weigh. (3) Tartaric Acid. — Weigh out 5 grams of the powder, transfer to a 500 c.c. flask, and add 100 c.c. of water and 15 c.c. strong hydrochloric acid. When all action has ceased, makeup with water to 500 c.c., and allow starch to subside. Filter and take 50 c.c. of filtrate and add thereto 10 c.c. of solution of potassium carbonate, containing 300 grams K2CO3 per litre ; boil for half an hour and filter into a porcelain dish, concentrate filtrate and washings down to 10 c.c., add gradually and with constant stirring 4 c.c. glacial acetic acid, and then 100 c.c. of 95 per cent, alcohol, stirring the liquid until the precipitate floating in it assumes a crystalhne appearance. After standing some hours, filter and wash with alcohol until entirely free from acetic acid. Transfer filter and precipitate to a beaker, add water and boil. Titrate the resulting solution with decinormal soda and phenolphthalein — 1 c.c. of alkali corresponds to 0-0188 grams of potassium bitartrate (cream of tartar), or 0-0150 grams of tartaric acid. (4) Sulphuric Acid. — This may be estimated without previous ignition of the powder. Weigh out 0-5 gram and digest in a beaker with strong hydrochloric acid until the whole of the powder including the starch is- dissolved ; then dilute with water, raise to near boiling, and add barium chloride in slight excess, allow to stand 12 hours, filter and weigh. (5) Alumina. — This body being the base of the alums, its determination should be made in all cases where sulphuric acid is found to be present. In the absence of phosphoric acid, from 0-5 gram to 1 -0 gram may be ignited, extracted with acid, evaporated to complete dryness to separate silica, treated with strong hydrochloric acid, diluted with water, and alumina precipitated with ammonia, washed, dried, ignited, and weighed. In the presence of both phosphoric acid and alum, the following method may be adopted : — Weigh out 5 grams of the powder in a platinum dish, heat until thoroughly carbonised, digest with strong nitric acid, dilute, and filter into a 500 c.c. flask. Wash the residue slightly, transfer the filter and all back into the platinum dish, dry, burn to white ash, add mixed potassium and sodium carbonates, and fuse. Take up with nitric acid, evaporate to complete dryness, again take up with nitric acid, dilute, and filter into the 500 c.c. flask. The flask will now contain both series of fil- trates ; make up to the mark with water. Take 100 c.c. and precipitate with ammonium molybdate and nitric acid, digest and filter. In filtrate, determine alumina by precipitation with ammonia, and estimate phosphoric acid in the precipitate in the usual manner. (6) Starch. — This may be determined by treatment with dilute acid so as to effect conversion into glucose, and then estimating by Fehling’s solution. A rough determination may be made by adding water to the powder, and after cessation of the reaction washing several times on a filter, first witli dilute hydrocldoric acid (5 per cent.) and then with water. The residue is transferred to a platinum dish, evaporated to complete dryness at 100° C. and weighed, subsequently to which the ash is determined and sub- tracted from the weight at 100° C. — the remainder is taken as starch. Other determinations may be made, but the above are the most important. . CHAPTER XXX. BREAD ANALYSIS. 893. Principles of Bread Analysis. — ^Having described the methods to bo employed for the determination of the various constituents of wheat and flour, a short description must now be given of bread analysis. Many of the properties by which good bread is distinguished from bad scarcely come within the range of purely chemical analysis. Among these are the colour, texture, “ piling,’" odour and flavour of the crumb, and the colour and thickness of the crust. In the kind of bread known technically as ‘‘ crumby ” bread, the colour and texture of the joint between two loavef^ is to be observed. The analyst, in reporting on bread, should examine the loaf so far as the above characteristics are concerned, and include his opinion on the same in his report. In judging each, he may adopt the plan of employing a series of numbers, say 1 to 10, and using the lowest number for the worst possible grade, and the highest for the very best. Or he may use instead the terms V. B., very bad ; B, bad ; I, indifferent ; M, moderate ; G, good ; V. G., very good ; E, excellent. In either case the same term must, so far as is possible, be applied to the same grade of quality, whether of texture, colour, or other characteristic. 894. Colour. — 'The baker’s use of this term involves a contradiction ; it is the custom of the trade to speak of a loaf as “ having no colour ” when a dark brown, while in the purest white loaf the colour is said to be “ high.” This is, of course, exactly opposite to the correct use of these terms, for white is strictly no colour, while a yellow or brown body is strongly coloured. It would be a better plan if the respective terms were “ lightly coloured ” and “ strongly or deeply coloured.” Judging colour by itself alone, the loaf should be a very light yellow or creamy tint, approaching almost to whiteness. This colour is selected because the authors are of opinion that, judging bread by the eye alone, the slightest yellow hue is more agreeable than an absolute snowy whiteness. The latter, perhaps from its frequent association with absence of flavour, is unpleasant. It must be remembered that colour, etc., are matters of individual taste and opinion, and therefore that each individual has his own standard of comparison. In forming a judgment one naturally most appreciates that in accordance with one’s own standard ; it does not necessarily folloAv that such judgment shall absolute^ agree with that of another person. It is a well-lmown fact that in different localities the standard of taste in these matters varies. For actual measurement of bread colour, the method of testing with the tintometer should be employed ; or baked loaves may be compared against those similarly prepared from standard samples of flour. 895. Texture. — ^The texture of a loaf is best observed by cutting it in two with a very sharp knife. There should be an absence of large cavities, and also of dry lumps of flour. The honeycombed structure of the bread should be as even as possible. The bread should not break away easily in crumbs, but should be somewhat firm. On being gently pressed with the fin- ger the bread should be elastic, and should spring back without showing a mark on the pressure being removed. 831 832 THE TECHNOLOGY OF BREAD-MAKING. 896. Proof. — ^Like many other trade terms, this is used in a somewhat different sense in different localities. It usually has reference to the degree of rise in volume a loaf undergoes before being put in the oven. In this sense, by a well-proved loaf is understood one that has risen well, both in the dough stage and after being placed in the oven. It almost goes without saying that in judging the quality of a loaf the baker likes it to be as large as possible. Such an opinion is a sound one where size of the loaf is combined with evenness of texture, and is not the result of the presence of large cavities in the bread. The opposite of a well-proved loaf is a heavy one ; hence this matter of the proof of a loaf is of importance. The loaf which in this particu- lar looks the best is that which is most digestible and wholesome. There is another sense in which the term “ proof ” is applied : thus, two loaves may have risen equally well, and yet the one be regarded as being better proved than is the other. The well-proved loaf is, under these cir- cumstances, viewed as that in which fermentation has proceeded until the flavour of the bread (the bouquet, if the term may be borrowed) has de- veloped to the greatest perfection. The well-proved loaf will be sweet and nutty in flavour, and have all the characteristics of being thoroughly cooked ; the badly-proved loaf will be lacking in flavour, and have what for want of a better expression, may be called a “ raw ’’ taste. Undoubtedly, this use of the term “ proving ’’ refers to a difference which does exist in the two loaves, a difference which in all probability is due to the more or less perfect proteolytic action of the yeast on the proteins during fermenta- tion. The term proof is therefore used in two different senses, one as a measure of the volume of the loaf, the other as an indication of the extent to which the changes accompanying fermentation have proceeded. 897. Pile. — ^This is essentially a term referring to the texture of the crumb of bread, and is doubtless derived from the use of the word “ pile as indicating the texture of the surface of velvet. In a letter, of which the following is the substance, Mr. W. A. Thoms explained to one of the authors the exact sense in which the term is used in Scotland : — “ By a well-piled loaf we do not understand a loaf well risen. Pile is the gloss of the outside skin, or crumb of close-packed bread, and the more unbroken the skin, the more silky in feel and glossy in sheen, the higher we rank the pile. Un- doubtedly a well-piled loaf must also be a well-risen loaf. They have that in common, but a well-risen loaf may be ragged, broken-skinned and dark, without being over proved ; such a loaf we call coarse, and say it has a bad or no pile. Proof, in dough or baked bread, refers to volume or size. These qualities , proof and pile, are due to the same factor, carbon dioxide, acting on and distending the gluten, and it is the condition of the gluten at the time in the oven, when the dough is passing into bread, that determines the pile. The condition, good or bad, of the gluten in this transition state may be due to the condition of the flour, the proportion of gluten it contains, or to the action of the yeast and its bye-products on the gluten during the entire fermentation. Unhealthy yeast will produce an abnormal propor- tion of acids, and acids render gluten first friable and then soluble. At the friable stage, bread may be high, badly shaped, dark and ragged, but defi- cient in pile.’' 898. Odour. — ^This is best judged by pulling a loaf open and burying the nose deep in the cleft. The bread should have a nutty, sweet smell ; this denotes the highest degree of excellence so far as this quality is con- cerned. There may be an absence of smell, or what is perhaps most forcibly described as a mawkish arid damp odour ; these belong to the indifferent stage. The bread may smell sour, in which case an unfavourable opinion is naturally formed. Beyond these are the smells, approaching to stenches, arising from butyric, ropy, and even putrid fermentation. BREAD ANALYSIS. 833 899. Flavour. — ^This of course is one of the most crucial tests of which bread can be put. It is probably the only one adopted by the vast majority of the bread-eating public. Fortunately, the judgment based on flavour is almost invariably a sound one ; a bread which pleases the palate is usually one that is wholesome. Having made this statement, it may be well also to indicate one direction in which the palate test is untrustworthy ; many people are extremely fond of hot rolls for breakfast. These luxuries are not, however, to be indulged in by every one, for hot bread is not easily digestible. The reason is a simple one ; the soft nature of bread, while still warm, causes it to be formed into balls in the mouth, wLich are swallowed without the due admixture with saliva. When tasting bread, nothing having a strong flavour should have been eaten for some little time previously ; a small piece of the bread should be put in the mouth, masticated, and allowed to remain there a short time before being swallowed. The flavour should be sweet, and of course there must be an absence of sourness or any marked objectionable taste. The physical behaviour of the bread in the mouth is also of importance. The bread should not clog or assume a doughy consistency in the mouth ; neither, on the other hand, must it be dry or chippy. In addition to tasting the dry bread, a slice spread with butter may be eaten. It need not be said that in this test the butter must be unexceptionable. 900. Colour and Thickness of the Crust. — The crust should be of a rich brownish yellow tint ; neither too light on the one hand, nor too dark on the other. So far as is consistent with adequate baking, the crust should be as thin as possible. The act of baking changes the character of several of the constituents of the flour. Thus, the albumin is coagulated, and thereby rendered in- soluble. The starch is partly, at least, rendered soluble by the gelatinisa- tion consequent on heating. The fatty matters of the flour are unchanged ; at times, however, bread is found to contain fat over and above that nor- mally present in flour. In fancy bread, butter or milk is sometimes used in the dough ; small quantities of lard are also employed by some bakers in order to give a special silkiness to the fracture where tw^o loaves of crumby bread are separated from each other. The ash is not materially affected in quantity, except in so far as it is increased by the addition of salt. The w'ater varies considerably. Subjoined are the results of some analyses col- lected by Konig and quoted by Blyth. A number of others by the authors are given in various parts of this work : — 1 Mini- mum. Maxi- mum. Mean for Fine Bread. j Mean for Coarse Bread. Water 26-39 47-90 38-51 41-02 Nitrogenous Substances . . 4-81 1 8-69 6-82 6-23 Fat 0-10 1-00 0-77 0-22 Sugar . . _ 0.82 4-47 2.37 2-13 Carbohydrates (Starch, etc.) 38-93 62-98 49-97 48-69 Woody Fibre 0-33 0-90 0-38 0-62 Ash 0-84 1-40 1-18 1-09 901. Quantity of Water in Bread. — ^The question may fairly be asked — On what principle is a decision to be made as to whether a bread contains too much water ? In reply, the loaf having become cool, say 2 hours after being removed from the oven, should on being cut feel just pleasantly 3 H 834 THE TECHNOLOGY OF BREAD-MAKING. moist, not dry and chippy, nor on the other hand in the slightest degree sticky or clammy. A second loaf, on being examined in the same way when 2 days old, should answer to tlie same tests, and should not show the shghtest signs of sourness or mustiness. Some loaves of bread containing even 40 per cent, of water would very well pass this examination ; while others which might contain much less water would nevertheless be damp and sodden, rapidly turning mouldy or sour. Notwithstanding that the latter contained absolutely the less water, they would still be condemned as containing more than they ought ; while the former would be returned as coming within the limit. The quantity of water permissible in a bread must depend on the nature of the flour used ; the offence is not in using sufficient water to a strong flour, but in adding more to a weak flour than it can properly take. Another question arises — Would it not be well for the public to insist on being supplied with bread made from such flours as normally require; for their conversion into bread, a low proportion of water ? Again, in reply, the strongest flours — that is, those which naturally absorb the most water — are made from the most nutritious, soundest, best matured, and highest class wheats ; so that the baker who uses a flour with high water- absorbing capacity, uses also a high priced flour. 902. Standard for Moisture. — ^By legal enactment the quantity of mois- ture present in bread of standard quality may not exceed 31 per cent, in the district of Columbia, U.S.A. (Foods and their Adulteration, Wiley.) As against this, Wiley regards 35 per cent, of moisture as being the average quantity in typical American high-grade bread (see paragraph 623). As an example of excessive water, Cameron states that bread supplied in August, 1896, to the troops at Clonmel, county of Tipperary, Ireland, contained per 100 parts ; — Water . . . . . . . . . . . . .. 58-28 Organic Matter . . . . . . . . . . .. 40-57 Ash 1-15 100-00 (Analyst, 1896, p. 255). 903. Analytic Estimations. — ^In an ordinary analysis of bread, where the object is not to test for audulteration, the estimations given below may be made. A thin slice should be cut from the middle of the loaf, the crust cut off, and then the interior portion crumbled between the fingers ; the crumbs must be thoroughly mixed, and at once placed in a bottle. Moisture, Ash, and Phosphoric Acid . — Determine as directed in para- graph 887 on Malt Extracts. Proteins . — Determine by Kjeldahrs method on 1 gram of the bread. Acidity . — Take 10 grams of the bread, grind up in a mortar with a small quantity of water, transfer to a flask, and make up to 100 c.c. Allow to stand for an hour in a boiling-water bath, cool, and titrate with A/IO soda, using phenolphthalein as an indicator. The acidity may be calculated as lactic acid. Fat . — Direct extraction of bread with ether or light petroleum spirit, however long continued, gives too low results, owing to the fat being enclosed by the starch and dextrin. The results are lower than those obtained from the flour from Avhich the bread was made. The following method, slightly modified from that suggested by Weibull, gives trustworthy results, but it is necessary to work exactly as follows : — 4 grams of new or 3 grams of stale bread or dried bread solids are put into a 70 c.c. beaker, and covered with 15 c.c. of water, after which is added 10 drops of dilute sulphuric acid (25 per cent.). The beaker is then placed in an ordinary saucepan containing BREAD ANALYSIS. 835 a little water, the lid put on, and the contents boiled gently for at least 45 minutes, or till the solution gives no starch reaction with iodine. While still warm, the contents are carefully neutralised with slight excess of powdered marble or pure precipitated calcium carbonate. The mixture is then heated over a water bath, or by standing on the top of the hot-water oven, until con- centrated to about 10 C.C., when it is spread on a strip of stout blotting-paper (such as is used in Adam’s milk process, being 22 inches long by 2J inches wide), and any liquid remaining in the beaker is removed by means of a piece of cotton-wool, which is then put on to the filter paper. The latter resting on iron gauze, is first dried for 10 minutes at 100° C. The paper is now rolled into the usual shape, and then dried for 3-4 hours at 100-103°. After this it is placed in a Soxhlett’s apparatus, and extracted for about 60 times with ether or light petroleum spirit, the extraction occupying in all about 5 hours. The ether solution is then evaporated, and dried in a Aveighed dish in the usual manner. The following analytic results show very clearly the relation between the fat as determined by direct extraction, that by W iebull’s method, and the fat contained in the meal or flour ; — I. Analysis of fancy loaf containing lard, the fat being determined by direct extraction. II. Analysis of same, by one of the authors, the fat being determined by the method above described. III. Analysis of same by another analyst, fat determined by similar method. IV. Analysis of plain bread, made and analysed by one of the authors. V. Analysis of fancy loaf containing according to the recipe J lb. of lard, made and analysed by one of the authors. VI. Analysis of “ all new milk ” bread, made and analysed by one of the authors. In the first table all the percentages of the various constitutents are calculated for purposes of comparison to the same proportion of water as was originally found in No. I. analysis. In the second table is shown the percentage composition of the bread in the dry state. Table I. Constituents. i II. III. IV. V. VI. Water 40-49 40-49 40-49 1 40-49 40-49 40-49 Proteins (Albuminoids), Gluten, etc. . . 7-55 7-32 — 7-43 7-55 8-74 Fat . . 0-96 1-85 1-81 0-95 2-16 1-84 Starch, etc. 38-97 — — — . — — ■ 1 Soluble INIatter, principally Carbo- 1 hydrates 10-30 12-16 12-19 6-31 15-18 8-16 1 Mineral Matter . . 1-73 — 1-87 Ml 1-37 1-28 j Table II. 1 I. II. III. IV. AU. ! Proteins (Albuminoids), Gluten, etc. . . 12-68 12-31 12-49 12-70 14-70 ' Fat 1-60 3-12 3-05 1-60 3-63 3-10 ! Soluble Matters, principally Carbo- hydrates 17-30 20-44 20-50 10-62 25-52 13-72 1 Mineral Matter . . 2-90 — 3-15 1-88 2-32 2-16 836 THE TECHNOLOGY OF BREAD-MAKING. The mixed meal used in Nos. IV., V. and VI. contained 1-47 per cent, of fat, equal to 1-69 per cent, in the meal in the dry state. Ordinary white bread contains on an average in the dried solids ; — Fat, 0-7 to 1*14 per cent. ; soluble matter, 5*0 to 8*0 per cent. ; ash or mineral matter, about 1-5 per cent., of which about I-O per cent, is common salt. In the recipe for the fancy loaf, the addition of the J lb. of lard, if the same is perfectly pure, raises the calculated percentage of fat on the dried bread solids by the amount of 2-07 per cent, which agrees almost exactly with the results of analysis. These figures do not confirm the view sometimes expressed, that a part of the fat of flour is in bread-making volatilised in the oven. Soluble Extract. — Take 25 grams of the bread and 240 c.c. of water, rub down with a little of the water into a perfectly uniform paste in a mortar. Transfer to a flask, add the remainder of the water and 1 c.c. of chloroform. Or, as an alternative method, the bread may be moistened with a little of the water and then rubbed through a fine sieve. The small thimble-shaped strainers, sold for attaching to the spout of a tea-pot in order to strain the tea, answer well for this purpose. The strainer is then washed with some more of the water and the whole transferred to a flask. Shake vigorously at intervals during 12 hours, or allow to stand overnight. At the end of the time shake again, and allow to stand for half an hour for the solids to settle. Filter the supernatant liquid until perfectly bright, and evaporate 25 c.c. to dryness for soluble extract. Bread contains on the average about 40 per cent, of water, and therefore there are 10 c.c. in 25 grams ; this quan- tity, together with the 240 c.c. added, make 250 c.c. The water extract may therefore be viewed as a 10 per cent, solution of soluble matters. There is probably no generally applicable method which extracts the whole of the soluble matter of the bread, as a portion is almost certain to remain behind. If, on the other hand, the bread be subjected to prolonged boiling, some of the constituents which were not originally soluble are thereby dissolved. It is not recommended to evaporate the bread to dryness, and make the determinations of soluble matters in the powdered dry residue, as this does not at all readily yield up its soluble matter to water. Maltose. — Usually 10 c.c. of the soluble extract solution may be taken and precipitated with Fehling’s solution in the usual manner. Should the amount of precipitate be very small, another 10 c.c. should be at once added. Soluble Starch and Dextrin. — These may be determined as described in paragraph 881, Chapter XXIX. Soluble Proteins. — Take 25 c.c. of the soluble extract solution, evaporate to dryness in a flask, and determine organic nitrogen by Kjeldahl’s process. The difference between total and soluble proteins may be returned as in- soluble proteins. Starch. — This is usually taken as difference, after making all other deter- minations ; but it may also be determined direct by either of the various processes given in Chapter XXIX. for estimation of starch. From the total starch, that estimated in soluble extract solution as soluble starch must be deducted. Cellulose. — This may be determined by the method described in para- graph 882. Digestibility . — The comparative digestibility of bread may be estimated by the method described in Chapter XVIII., paragraph 603. Modifications may be made in the strength of the digestive agents, and the temperatures employed. A useful alternative method consists in first digesting for 3 hours with the acid solution of pepsin, and then adding twice as much normal sodium carbonate solution as necessary to neutralise the acid present. A similar quantity of pancreatin is then added and the digestion continued for another 3 hours. CHAPTER XXXI. ADULTERATIONS AND ADDITIONS. 904. Standard Works on the Subject. — ^In giving directions for both flour and bread analysis, the authors have hitherto confined themselves to such modes of testing as enable one to determine the quality and charac- ter of each, apart from any considerations as to the presence or absence of any foreign bodies. The present chapter contains an outline of the processes employed in the analysis of flour, bread, and certain other sub- stances, for the purpose of detecting adulteration. This branch of chem- istry applied to the arts of milling and baking has received considerable attention, and several standard works of reference have been vTitten on the subject ; among these may be mentioned those of Allen and Blyth, both of which represent the most recent and authoritative opinions of chemists on the problem. For several of the tests to be hereafter described the authors are indebted to these works, to which the student is referred for further and more detailed information. 905. Information derived from Normal Analysis. — Some of the tests aheady mentioned in the description of the normal analysis of flour and bread serve also as indications as to whether a sample is adulterated. Thus the moisture, if unduly high, points to the fact that at some stage of manu- facture, water has been added to the wheat, stock, or flour ; water added for other purposes than normal conditioning or improvement of the grain nr stock must be regarded as objectionable. The percentage of ash in the flour affords some guide as to whether the sample has been treated with mineral substances. A flour ash, when pro- perly burned, should amount to less than 1 per cent. ; greater quantities than this are probably due to mineral adulteration. Reference has already been made to certain considerations arising out of the presence of undue ash for the colour of the flour. See paragraph 815. 906. Impurities and Adulterants of Flour. — ^The following are some of the foreign substances that are at times found in the ground form in flour ; seeds of other plants, as corn-cockle and darnel ; blighted and ergotised grains — these are to be viewed rather as impurities than adul- terants, the latter term being confined to those bodies wilfully added for purposes of fraud. Among these latter are rye, rice-meal, maize flour, potato starch, meal from leguminous plants, as peas and beans, and alum and other mineral bodies. The question of the addition of mineral sub- stances as “improvers ” has been already discussed in Chapter XX. The tests for many of these substances are in part microscopical ; the chapters containing directions for practical microscopic work provide information and data as to the making of such tests. The following are the principal chemical tests for the bodies above mentioned : — 907. Darnel. — ^Treat a little of the flour with alcohol (rectified spirits of wine, not methylated spirits), digest at 30° C. for an hour, shaking occa- sionally. Filter and examine the filtrate. This should be clear and colour- less, or at most should be only of a light yellow colour. In the event of the 837 838 THE TECHNOLOGY OF BREAD-MAKING. flour containing darnel, the alcoholic extract is of a greenish hue, and has an acrid and nauseous taste. Treatment with alcohol and a small quantity of acid is a useful test for other adulterants. Extract the flour with 70 per cent, alcohol [i.e., a mixture of alcohol and water, containing alcohol equivalent to 70 per cent, of absolute spirit), to which 5 per cent, of hydrochloric acid has been added. Pure wheat or rye flour yields a colourless extract ; barley or oats gives a full yellow tint ; pea-flour, orange-yellow, mildewed wheat, purple- red, and ergotised wheat, a blood-red colouration. 908. Ergot and Mould. — ^To test flour for ergot, exhaust 20 grams with concentrated alcohol in a fat extraction apparatus ; notice the colour, which in the presence of ergot is more or less red. Mix this solution with twice its volume of water, and shake up separate portions of this mixture with ether, amyl-alcohol, benzol, and chloroform. Ergot imparts a red colour to the whole of these solvents. Vogel recommends the flour should be stained with aniline violet, and then examined under the microscope ; should any of the starch granules have been attacked by ergot or other fungoid growths, they acquire an intense violet tint ; while if they are perfectly sound, they remain compara- tively colourless. Ergotised flours evolve the peculiar flsh-like odour of trimethylamine when heated with a solution of potash : the same smell is, however, evolved by flour otherwise damaged. The test is of service in distinguishing between sound and unsound flours. The use of mouldy wheat for the manufacture of flour can be detected by placing the sample in a tightly stoppered bottle, damping it and placing it in a bath heated to about 30° C. Any mouldy taint can readily be observed after thus standing for 2 or 3 hours. 909. Rice in Flour, Gastine. — Gastine recommends for the detection of rice in wheaten flour its treatment with a colour stain. A trace of the flour is treated with a solution of 0-05 gram of aniline blue in 100 c.c. of 33 per cent, alcohol. The flour is then dried at about 30° C., and Anally by heating for a few minutes at 110-130° C. The preparation, is then mounted in cedar-wood oil and examined under the microscope. Treated in this man- ner the wheat starch granules are almost invisible and very rarely do they even exhibit a visible hilum. On the contrary the hilums of the minute rice starch granules show up very distinctly, and usually in regular clusters, since each fragment of rice is generally built up of a number of starch gran- ules. When wheat granules are cracked, the Assures show very distinctly as a result of the infiltration of nitrogenous matter, which readily takes the stain. Granules of maize and buckwheat starches behave like rice. {Comptes rend., 1906, 142, 1207). 910. Maize Meal in Wheaten Flour, Kraemer. — ^Kraemer states that flours containing corn-meal give off an odour of roasting corn when heated in glycerin to boiling for a few minutes. {Jour. Amer. Chem. Soc., 1899, 662.) 911. Maize Starch in Wheaten Flour, Baumann. — ^For the detection of maize starch (corn flour) in wheaten flour, Baumann recommends the follow- ing test : — About OT gram of the flour under examination is mixed with 10 c.c. of a 1-8 per cent, solution of potash, and the test tube shaken at intervals during 2 minutes. Four or five drops of 25 per cent, diluted hydro- chloric acid are then added and the tube again shaken. The liquid must still be slightly alkaline in order to prevent the precipitation of the dissolved proteins. A drop is taken out and examined under the microscope, when the wheat-starch granules will be found to be completely ruptured while ADULTERATIONS AND ADDITIONS. 839 tliose of maize are unaltered. As little as from 1 to 2 per cent, of maize can thus be detected. The test may be employed quantitatively by taking mixtures containing known quantities of maize starch, treating them in the same way as the sample under examination, and deciding which matches it when drops of similar size are microscopically examined. The same method is applicable to the detection of maize in rye flour. [Zeits. /. Unter- such. Nahr.-u Genussmittel, 1899, 2 [1] 27.) 912. Maize in Wheaten Flour, Embrey.— Embrey has not found the foregomg process to give satisfactory results in his hands, and has therefore devised and recommends the following modification : — Mixtures of pure wheat and maize flours are prepared containing respectively 10, 15, 20, 25 and 30 per cent, of the maize. Weighed quantities (0-2 gram) of each of these, and of the sample under examination, are placed in test tubes (15 c.m. X 2 c.m.) which are fitted with paraffined corks. To each is added a quantity of 20 c.c. of potassium hydroxide solution (18 grams per litre), and the tubes shaken uniformly for 3 minutes. Twelve drops of diluted hydro- chloric acid (HCl of specific gravity 1T6, 50 c.c. ; water, 100 c.c.) are next introduced and the tubes shaken, and then whirled in a centrifugal machine at 600 revolutions per minute. One c.c. of the clear liquid is transferred to a Nessler tube and diluted to 50 c.c., after which 1 c.c. of an iodine solu- tion (I, 0-25 gram ; KI, 1 gram ; water to 250 c.c.) is added. The tint obtained compared with those of the standard tubes gives the proportion of maize within about 5 per cent. For a more exact determination, 10 c.c. of the clear liquid from each tube are boiled for 2 hours with 1 c.c. of dilute sulphuric acid (1 : 7), then neutralised, diluted to 50 c.c. and run from a burette into a boiling mixture of Gerrard's solution, 10 c.c., and Fehling's solution, 2 C.C., until the colour is discharged. The percentage of maize is obtained from the standard tube of which the same amount is required to discharge the colour. Gerrard’s Solution is prepared by diluting 10 c.c. of freshly prepared Fehling’s solution with 40 c.c. of water, and adding a solution (about 5 per cent.) of potassium cyanide from a burette, until the blue colour is only just perceptible. During the addition of the cyanide, the diluted Eehling’s solution is kept boiling and constantly stirred in a porcelain dish. {Analyst, 1900, 25, 315.) This process is really an estimation of the soluble starch resulting the rupture of the granules of wheaten starch by the action of potassium hydroxide solution. In the first method it is directly estimated as starch by a colori- metric process with iodine ; and in the second by conversion into glucose and then volume trically by a modification of Eehling’s solution. An objec- tion to the method is that variations in the proportion of wheaten starch in a flour may be due to causes other than the presence of maize. Thus a very weak flour may contain more starch than a very strong one, and if the former be also exceptionally dry and the other comparatively moist the difference is still further enhanced. Also, if even as much as 30 per cent, of maize flour is contained in the flour the actual reduction in wheat starch is only approximately from about 70 to 50 per cent. On the other hand the amount of maize flour will have been increased from zero to 30 per cent. ; obviously, therefore, a direct estimation of the maize starch is preferable if practicable. As a modification of Embrey's method it is suggested that the solution of clear starch should be decanted off, the insoluble residue thoroughly shaken up with water, and again whirled in the centrifugal machine, so as to free it as far as possible from soluble starch. The residual maize starch may then be dissolved by heating with water, and estimated either colorimetrically with iodine, or by conversion into glucose and esti- 840 THE TECHNOLOGY OF BREAD-MAKING. mation by Fehling’s solution. The most important point here is whether or not the sediment is practically free from soluble wheaten starch. In the discussion on the above paper, Bevan mentioned with approval a qualitative method devised by W ilson, and consisting of mixing the flour with clove oil, and examining with a J or |^-inch objective, when the hilum of maize appears as a black dot or star, while wheaten and other starches are practically invisible. 913. Starch in Yeast. — ^Bruylants and Druyts recommend the following method of estimating flour or starch in yeast : From 50 to 100 grams of the yeast are to be taken according to the suspected quantity of starch, and mixed thoroughly with a dilute solution of iodine in potassium iodide. The mixture is, if necessary, passed through a fine sieve in order to remove any large sized fragments of impurity. It is then allowed to settle, when the starch falls first, until the starch is covered by a thin layer of yeast. The yeasty liquid is poured away and this washing by decantation continued until only starch remains. A little fresh iodine must be added from time to time. The sediment is dissolved and converted into glucose by heating with dilute (2 per cent, hydrochloric acid), and then estimated in the usual manner. In tests made on yeasts containing known quantities of starch, ranging from 3 to 15 per cent., the amounts recovered by the method ranged between 96-7 per cent, and 100*8 per cent, of the added starch. [Bull. Assoc. Beige des China., 13 [1] 20.) Instead of dissolving the starch obtained by this process in hydrochloric acid, it may be estimated direct by first washing with strong alcohol and then evaporating and drying in a tared dish. Comparative experiments should be made on yeasts to which known quantities of starch have been added. 914. Aniline Blue in Flour, Violette. — ^Violette states that blue colouring matter is sometimes employed in order to counteract the yellow tinge of flour. In order to detect such addition a sheet of white filter paper is floated on the surface of water, and a little of the suspected flour sprinkled thereon. In the presence of aniline colours, dark specks soon appear on the paper, which grow in size and form blue spots. [Bull. Soc. China., 1896, 15, 456). . 915. Mineral Adulterants and Additions. — ^The presence or absence of most foreign mineral matters will have been indicated by the percentage of ash yielded. Alum is, however, added to flour in quantities too small to be thus detected. One of the most ready means of separating mineral substances from flour is by means of what is termed the 916. Chloroform Test. — ^This test depends on the fact that chloroform has a density higher than that of the normal constituents of flour, but lower than that of minerals generally ; consequently, on agitating a mixture of flour and chloroform, and then allowing it to rest, the flour rises to the surface, and any mineral adulterants sink to the bottom. On the small scale, for the purpose of a qualitative test, a large dry test-tube may be about one-third filled with the flour, then chloroform added to within one inch from the top. The tube must then be corked and violently shaken, after which it must be allowed to rest for some hours ; the mineral matter will then be found to have sunk to the bottom. For quantitative purposes a glass “ separator is requisite. This is a cylindrical vessel some 2 inches in diameter, 8 or 10 inches in length, stoppered at the top, and furnished with a stopcock at the bottom. Introduce in this vessel 100 grams of the flour and about 250 c.c. of methylated chloroform ; treat as directed for the smaller quantity. When the separation is effected, open the stopcock and allow any sediment, with as little as possible of the liquid, to run through. ADULTERATIONS AND ADDITIONS. 841 Treat this again with a little more chloroform in a smaller separator, and once more drain the sediment off through the stop-cock into a watchglass, •or small evaporating basin. Allow the chloroform to evaporate ; treat the dry residue with a small quantity of water, and filter. Any plaster of Paris ■calcium phosphate, or other insoluble mineral matter will remain on the filter, and may be ignited and weighed. Evaporate the solution to dry- ness, and examine the residue carefully with a low power under the microscope for any crystals of alum. In making this test, flours, which are absolutely free from any added mineral matter, occasionally give a slight sediment. This was formerly ascribed to the presence of detritus from the millstones ; but this can scarcely be an adequate explanation, as the authors have obtained such sediment from pure roller-milled flours. 917. Special Test for Alum. — The most convenient test for alum in flour consists in adding thereto an alkaline solution of logwood. Take 5 grams of recently cut logwood chips and digest them in a closed bottle with 100 c.c. of methylated spirit. Also make a saturated solution of ammonium carbonate. Mix 10 grams of the flour with 10 c.c. of water, then add 1 c.c. of the tincture of logwood and 1 c.c. of the ammonium carbonate solution, and thoroughly mix the whole. With pure flour the resultant mixture is of a slight pinkish tint. Alum changes the colour to lavender or full blue. The blue colour should remain on the sample being heated in the hot-water oven for an hour or two. 918. Mineral Matters in Solution. — Certain mineral matters are at times added to flour in the state of solution, the solution being sprayed into the flour or added to a portion of the stock which is then dried, ground, and mixed in with the flour. If this operation is performed with sufficient care no particles of the flour are sufficiently weighted by the adherent mineral matter to sink in chloroform, and so the appHcation of that test fails to reveal the presence of such added mineral matter. Very frequently, how- ever, some portion of the flour has absorbed sufficient of the mineral addition to sink in chloroform. If so, this portion should be thus separated and the ash in the two portions determined. Any difference detected is an indica- tion of the addition of some foreign mineral. The nature of the substance added may be ascertained by further analysis of the ash. In cases where it is desired to test particularly for sprayed additions of mineral salts, it is well to compare the total ash of the flour with that of a sample of known purity of the same colour and grade, bearing in mind Snyder’s conclusions on the relation between ash and grade of flour already given (paragraph 815). In this connection it must be borne in mind that a bleached flour will contain less ash than a corresponding unbleached flour. In the next place apply the chloroform test as described. Should this fail, add to the chloroform and flour in the separator, absolute alcohol in small quantities at a time, and shake and allow to settle between each addition. As the mixed liquid approaches in density to that of flour, a point is reached at which any mineral-w'eighted particles of flour may sink and the purer portion float on the top. In this case separate the two and determine the ash in each separately. If deemed necessary, make analyses of each portion of ash. Should the whole of the flour have absorbed the mineral addition with absolute uniformity, a separation cannot of course be effected by this method. But in all such methods of introducing foreign mineral matters, some portion of the flour is almost certain to have absorbed more mineral matter than others. If the addition is exceedingly small, this mode of separa- tion is not likely to be effective, and recourse must be had to a more or less complete analysis of the whole ash. The finding of any substance in a 842 THE TECHNOLOGY OF BREAD-MAKING. quantity beyond the extreme amount that may occur as a natural consti- tuent of flour is evidence of its presence as an added body. In the event of the addition of mineral substances to a flour which is naturally deflcient in those substances, and in such quantity as not to exceed the normal amount which may be present, then even a complete analysis of the ash may fail to reveal the fact of mineral bodies having been added. More usually, however, any such additions will not have the same proportionate composition as normal flour ash, and in this way their presence will be indicated. 919. Alum in Bread. — -Bread is tested for alum by first taking 5 c.c. of the tincture of logwood, 5 c.c. of the ammonium carbonate solution, and diluting them down to 100 c.c. This mixture must at once be poured over about 10 grams of the crumbled bread in an evaporating basin. It is allowed to stand for 5 minutes, and then the superfluous liquid drained off. Slightly wash the bread and dry in the hot-water oven. Alum gives the bread treated in this manner a lavender or dark blue colour, which is intensified on drying. Pure bread first assumes a light red tint, which fades into a buff or light brown. After some practice this test gives satisfactory results, and is so sensitive that as little as 7 grains of alum to the 4 lb. loaf have been detected. The depth of colour affords a means of roughly esti- mating the quantity of alum present. It is essential that the tincture of logwood be freshly prepared, and that the test be made immediately after mixing the tincture of logwood and ammonium carbonate solution. 920. Young on Longwood Test for Alum. — ^In 1886 Young pointed out (The Analyst) that under certain circumstances bread which is absolutely free from alum gives the characteristic reaction wuth logw^ood. On investi- gation it was found that the flour used gave no indication by logwood, but that the bread gave a very distinct colouration. The sample was heavy and sour — subsequent experiments showed that the colouration was directly due to the acidity. On taking pure breads, which were absolutely negative to the logwood test, and moistening with dilute acetic acid (1 to 250 of water), and letting stand for one hour, all gave a most intense blue colour with logAVOod. So also did pure flour similarly treated. Young considers this effect to be due to phosphate of alumina (a body normally produced from the mineral constituents of flour), being slightly soluble in dilute acetic acid, and quotes experiments in proof of this solubility. He further found that such phosphate of alumina exists in a state of combination with the gluten, and, as a result of careful washing, was able to procure starch,. Avhich, after treatment wdth acetic acid and subsequent application of the logwood test, gave no colouration. In a quantitative experiment some best quality Hungarian flour was taken, yielding 0-7 per cent, of ash and 8 per cent, of dry gluten The gluten was washed out in a muslin bag and dried, 20 grams Avere taken, finely poAA'dered, and treated AAoth 250 c.c. of 50 per cent, acetic acid, and heated in the Avater bath for 28 hours. The gluten had then dissolved, leaving a sediment, from AAPich the clear liquid AA^as poured, and the residue again tAAUce treated in the same manner AAuth the diluted acetic acid. The three lots of acid extract AA'ere evaporated to dryness, and the residue burned to a perfect ash — this Avas treated in dilute hydrochloric acid, and the insolu- ble residue fused AA'itli alkaline carbonates, dissolved in dilute hydrochloric acid, filtered, and filtrate added to acid solution of ash. This Avas again evaporated to dryness, redissolved in small quantity of hydrochloric acid, filtered, filtrate boiled, and cautiously added to 25 c.c. of saturated solution of pure sodium hydroxide, also boiling, and kept boiling for a feAV minutes. The precipitate AA'as dissolved AA'ith hydrochloric acid, and precipitated Avitli saturated solution of sodium phosphate and slight excess of ammonia. ADULTERATIONS AND ADDITIONS. 843 After 10 minutes’ boiling, the precipitate of aluminium phosphate was collected, filtered, and weighed. The 20 grams of gluten yielded 0-0185 gram of aluminium phosphate, equal to 0-01875 from 250 grams of fiour, or 0-0075 per cent. Alumina was thus shown to be a natural constituent of flour, and associated with the gluten. The alumina thus normally present justifies a deduction being made of from 7 to 8 grains of alum per 4 lb. loaf from the amount corresponding to total alumina by analysis. For further experiments by Young on the solubility of aluminium phos- phate in acetic acid, the reader is referred to The Analyst for April, 1890. He there shows that the presence of ammonium acetate, and also that of ammonium chloride, prevent the complete precipitation of aluminium phos- phate in the presence of acetic acid. 921. Calcium Sulphate in Bread. — -Calcium sulphate is occasionally found as an added substance in bread. The addition is probably due to the aeration of the bread by a phosphatic baking powder, in which the acid phosphate contains calcium sulphate as a natural impurity. As only traces of sulphates exist ready formed in the cereals, they may be detected by an examination of the unignited bread. The best plan is to soak 12-20 grams of the bread for some days in 1200 c.c. of cold distilled water until mould forms on the surface of the liquid. The solution is then strained through muslin and the filtrate treated with 20 c.c. of phenol distilled over a small quantity of lime. The whole is then raised to the boiling point and filtered through paper ; 1000 c.c. of the filtrate are slightly acidulated with hydro- chloric acid and precipitated in the cold by barium chloride. Every 237 parts of barium sulphate represent 136 parts of calcium sulphate. {^Allen's Commercial Organic Analysis, vol. 1., p. 460.) 922. Mineral Oil for Parting Loaves. — ^In the case of close-packed bread it is the custom to smear the contiguous surfaces of loaves with melted lard or oil for the purpose of preventing their sticking together. For this pur- pose a petroleum residue is employed (1896) in Germany, known as Brotel. Illness has been traced to this practice in Hamburg, the residue remaining in the loaf and causing digestive disturbances. {Jour. 8oc.Chem.lnd., 368, 1896.) 923. Colouring Matter in Cakes. — ^In order to determine whether cakes and other confectionery have been coloured with yolk of egg, or with other colouring matters, Spaeth recommends that the fat be extracted and ex- amined. The following are the characteristics of egg -yolk fat and wheat meal fat respectively : — Sp. g. at 100° C. (water at 15°=1*00) Melting point of fatty acids Saponification number . . Iodine value ,, ,, of fatty acids Reichert-Meissl value . . Refractive index at 25° C. ,, ,, on Zeiss refractometer scale Egg Fat. Wheat Fat. 0- 881 0-9068 36° 34° 184-43 166-5 68-48 101-5 72-6 — 0-66 2-8 1- 4713 1-4851 68-5 9-20 When the iodine value exceeds 98, and the phosphoric acid (P2O5) in the fat is below 0-005 per cent., there cannot be more than traces of egg -yolk. {Analyst, 233, 1896.) In this proposed method, no cognisance is taken of the fact that cakes and similar articles have large quantities of butter and other fats added to them, the constants of which may vary widely from those of either egg-yolk or wheat fats. CHAPTER XXXII. ROUTINE MILL TESTS. 924. Practical Adaptation of Flour Tests to Mill Routine.— The fore- going chapters have contained descriptions of the modes of making various flour tests and the conclusions to be drawn therefrom. There now remains for discussion the problem of their adaptation to commercial milling routine. This may be done in two ways, either by the employment of a chemist at the mill, or by sending samples by arrangement to a chemist who under- takes work of this class. In either case some special training is requisite. A professional knowledge of the science of chemistry and the principles of analysis is of course essential ; but in addition to these a chemist who under- takes the work of commercial flour analysis should be familiar with the general properties of wheats and of flour. He should also have had suffi- cient experience of the physical methods of testing employed by both miller and baker, and of the carrying out of baking tests under conditions of scien- tific accuracy. In cases where it is decided to carry on such work at the mill, a laboratory must be provided ; of this some description has been already given in Chapter XXV. on Analytic Apparatus. 925. Dispatch of Samples and Results. — ^If the alternative is adopted of entrusting these duties to an outside chemist, then arrangements must be made for the collection of the necessary samples and their dispatch. It should be made the special business of some responsible person to take the samples at some specified time. This person must be familiar with the process of sampling, and must take care that the samples are properly representative of the bulk. The quantities must depend on the nature of the tests to be made. Among some of the most frequent of such tests are those of moisture. For each of these an ounce of the material is sufficient. Having regard to the ease with which wheat products either absorb or lose moisture, the samples for this purpose must at once be packed in air- tight receptacles. Probably the most convenient form is a glass tube of the requisite size, fitted with an india-rubber cork. Special wooden blocks are made for holding these for postal purposes ; any desired number can then be packed in the one block and dispatched by post. For an ordinary analysis, an 8 oz. sample is a suitable quantity, and a convenient pack- age consists of a small bag made of fine close-textured canvas or similar material. This in turn should be enclosed in a tin canister with tightly fitting lid. Wooden boxes should be provided to hold a certain number of these canisters, for dispatch to the chemist’s laboratory. The locks of tliese boxes should be provided with two keys to be held respectively by the forwarder and recipient. A systematic course of labelling must be adopted. Tlie labels should be affixed to the bags or glass tubes, and not to the covers of canisters or the corks of tubes. The reason is that the identifying label must not be capable of detachment from the sample by the act of opening the package. Further, the label should bear the name and address of the sender. A ])roper dispatch book must be kept in which descriptions of samples, identify- ing marks or numbers, and dates of dispatch are entered. For baking tests, ROUTINE MILL TESTS. 845. ! a larger sample must be sent, and for this 2 lbs. is a very convenient quan- Ij tity. Larger bags of the same kind of material as before are on the whole Ij most suitable. It is not absolutely necessary that they be enclosed in tin ; canisters, but they should also be packed in wooden boxes. The sample sent for baking will also serve for the other analytical texts, except that for moisture. The small samples for this purpose should always be packed in the air-tight tubes ; and the larger carrying boxes may be easily fitted ; with a small division to hold the tubes. The packed sample cases should so far as possible be regularly forwarded by a certain mail or train. There are very few districts in which samples cannot be dispatched in the evening i so as to be in the hands of the chemist early the next morning. He will of course be perfectly familiar with the routine of treatment on their reception,, the only suggestion to be made being that such results as are wanted most quickly should be arranged for first. For example, moistures are fre- quently required with the utmost expedition, and the determinations should therefore be started immediately. In returning results, they may frequently require to be sent by tele- graph ; in that case a code should be arranged by which the data could be sent cheaply and with the least possible risk of mistake. A certain number of figures can always be sent as a word ; but figures are prone to mistakes in transmission, and above all such mistakes are not evident on the face of them. Code words are not so liable to the same errors, and should there- fore be used in preference. As an example, the following is a convenient and simple code for the transmission of moisture results. 9*0 Aback 10*0 Babel 11*0 Cabin 12*0 Lark 9*1 Abbey lO-l Bank IM Cask 12-1 Late 9*2 Accent 10*2 Beach 11*2 Chart 12*2 Lean 9*3 Adder 10*3 Beef 11*3 Civil 12-3 Lell 9*4 Affix 104 Bird 114 Clamp 124 Lip 9*5 Agate 10*5 Blank 11-5 Clock 12*5 Li van 9*6 Aisle 10*6 Blow 11*6 Code 12*6 Lock 9*7 Alarm 10*7 Boast 11*7 Court 12-7 Lose 9*8 Ambit 10*8 Box 11-8 Crest 12-8 Lrag 9*9 Anchor 10*9 Buoy 11*9 Cube 12*9 Luel 13*0 Ear 14*0 Fault 15-0 Gas 16-0 Hack I3-I Ebb 14*1 Fear 15*1 Gear 16*1 Hair 13*2 Echo 14-2 Feud 15-2 Gem 16-2 Head 13*3 Eddy 14*3 Field 15-3 Gill 16-3 Help 134 Eel 144 Fight 154 Give 164 Hide 13*5 Effect 14*5 Flock 15*5 Gland 16-5 Hint 13-6 Egg 14*6 Foam 15-6 Good 16-6 Hoax 13*7 Ember 14-7 Fowl 15*7 Gout 16-7 Hole 13*8 End 14*8 Freak 15*8 Grain 16*8 Hulk 13*9 Equip 14*9 Fury 15*9 Gust 16-9 Hurt All telegraphic results must be confirmed by post, to be in the hands of the miller at a regular time. and dispatched so as 926. Standard Quality. — ^It must be borne in mind that high quality is not a fixed and invariable standard, but depends largely on what are local requirements. This question most generally arises when systematic tests are for the first time introduced, and requires its proper answer in each individual mill before such tests can yield results of much value. That which is the best flour in the one district is not the best in another, and therefore the chemist first requires to know the exact kind of flour the miller 846 THE TECHNOLOGY OF BREAD-MAKING. M'ishes to make. The miller can usually lay his hands on one particular parcel, which has the approval of his most skilful and critical customers, which he would like always to supply, and which he would be content to take as a standard. If he can also obtain certain samples which more or less fall short of this standard, and with clearly marked defects, they will also be of service. The chemist should be supplied with these samples, and his first object should be to find out where the faulty examples differ from the standard one. No precise directions can be given for doing this, since it is here that the skill and judgment of the expert are brought to bear on the problems of each particular flour. Care should be exercised in discriminating between differences which are accidental and those which are fundamental. From these data the requirements in the standard flour for each particular mill are formulated, and the effect of any departures from the standard of quality are duly noted. This is a judgment which cannot be formed immediately ; the first opinion must only be looked on as provisional, and must be confirmed or otherwise by subsequent tests. Still it is remarkable how soon, as a result of regular testing, the chemist forms an opinion on the quality of the flour and recognises any deviation. These opinions are usually confirmed by subsequent baking tests. 927. Uniformity in Quality. — ^Having formulated standards for each miller’s requirements, the next object is to see that flours of these qualities are being uniformly produced. For this purpose flours are regularly tested. The first and simplest object of such tests is to serve as a control on the working of the mill, and to secure the most help from such tests the miller (Le., the working miller) should work in unison with the chemist. So far from being antagonistic, their real duties are complementary, and any real improvement is largely dependent on their mutual co-operation. The miller will take samples from those parts of the mill which will afford the most information, and the chemist will duly test same. In particular if suspicion attaches to the work of any particular machine or part of the mill, samples of the products of this section will receive special attention. In this way tests are made, and the results carefully recorded. In cases where any marked departure from the usual standard occurs, attention should be drawn to it, and the flour watched in its future stages so as to note whether it has been found in any way unsatisfactory in actual use. 928. Actual Routine Tests Employed. — ^Of set purpose the selection of these is left to the judgment of the individual chemist. In previous pages the nature and objects of the most important tests have been described in detail. The following are among those which will probably be regularly employed. Moisture . — This test has a very important bearing on the whole question of the conditioning of wheat. Samples may be tested of the whole wheat unmoistened and after the moisture has been added by any means. The comparison of these shows how much water has actually been added. Then tests may be made on the whole wheat, the flour, and the bran. These will show how far and to what extent the moisture has penetrated. Lack of penetration may be due to a particularly hard bran, or it may be the result of conditioning not having been carried out sufficiently long before grinding. Where any system of improving treatment is carried out as a part of the conditioning process, or by the spraying of either stock or flour, the moisture tests serve the secondary purpose of determining the quantities of the improving agents which have actually been added. Moisture tests, intelligently applied, have therefore most important uses in the mill. Ash . — As a control on the degree of length of patent, regular ash deter- . minations are exceedingly valuable when properly made. Protein Estimations . — The details of them have been given most fully. ROUTINE MILL TESTS. 847 Tlie selection must depend on individual judgment. Total proteins, gluten, ' and alcohol-soluble proteins will probably be included in most schemes of i protein determmations. Water -Absorption . — Viscometer tests not only measure an important property of flours, but also one which serves as a most important check on uniformity of production. Colour . — In every well conducted mill, the colour of flour is always being carefully watched. This is especially necessary where any bleaching process is being employed. 929. Replacement Tests. — Tests for uniformity are not confined to being a check on the satisfactory working of the mill, but they have a further most important bearing on the difficult question of replacing in a mixture one wheat by another. Some useful general information on this point is given on page 282, but that scarcely more than touches the fringe of the problem. To start with, the same kind of wheat varies with its age, and as the crop from a fresh harvest arrives it must be carefully tested before it can be regarded as the equivalent of that of the preceding year. When a miller is grinding a mixture of several varieties of wheat, and one of these runs out, it is imperative that any proposed substitute shall not seriously alter the character of the flour produced. In making the change he is limited by the facts that the average price of the wheat composing his mixture must not exceed a certain amount, and that the various grades of flour he manu- factures must all maintain their specific qualities ; and so far as possible must be produced in their usual proportions. In making any tests on the whole wheats, they may be reduced to fine meal, and the results of gluten or other determinations calculated out on the assumption of a 70 per cent, yield of straight-run flour. Evidently this can be nothing more than an assumption, because the flour yield of wheats varies within wide limits. Again, for reasons on which the previous subject matter will have thrown some light, the mixmg of various wheats does not always produce the expected results. A mixture of strong and weak wheats having a known percentage of gluten, for example, sometimes yields a loaf which is quite appreciably better or worse than was expected, and there is always some anxiety as to the result of a new blend until test bakings have been made on the resultant flour. 930. Milling Tests. — ^The only true test under these circumstances is the milling test, in which the various wheats are ground separately and their resultant flours tested chemically and by baking. They should then be mixed in the desired proportions and again tested until such a blend is obtained as satisfies the miller’s desideratum — a maximum of quality at a minimum of cost. With very small milling plants it is the custom to make a trial by putting a few sacks of a newly arrived wheat through the entire mill. But while this is a tedious and expensive experiment with a small plant, it is practically an impossibility with a large one. The obvious alternative is to lay down a small milling plant for experimental purposes. This must not be too large, and yet must be large enough to make a fairly good commercial sample of flour. A very convenient plant for making these tests has recently been intro- duced, which consists of a machine that in a condensed form is able to per- form all the operations of a gradual reduction roller plant built in one frame, driven by one main belt and taking up a very little space. This machine is illustrated in Fig. 122, and embodies within itself two pairs of “ Break ” or fluted rollers, a sieve between the first and second pair, a centrifugal ■dressing machine to dress the flour from the first break meal and another 848 THE TECHNOLOGY OF BREAD-MAKING. to deal with the second break stock and tail over the bran to the sack. There is then left the semolina from the tails of the first centrifugal and the bran middlings from the “ Cut-off ” of the second break centrifugal, to be ground on two pairs of smooth reduction rollers in sequence, each of which is suc- ceeded by a flour dressing reel. The whole process is entirely automatic from the incoming wheat to the marketable products of flour, bran and sharps. Fig. 122. — Midget Testing Mill. This useful little appliance, which goes by the name of the “ Midget,’^ and is made by Messrs. Alfred R. Tatter sail and Co., 75, Mark Lane, London, E.C., lends itself admirably to the testing of small parcels of wheat, as its capacity is to make from 140 to 280 lbs. of finished flour per hour. By its means a grist can be made from two or even one sack of wheat, and a very passable yield can be obtained. While the results got on this machine may not be identical in every respect with those got on the larger and more elaborate systems, they yield trustworthy comparative results. Fig. 123. — Wheat Cleaning Machine, ROUTINE MILL TESTS. 849 A very useful adjunct to testing mills is a cleaning machine made by Messrs. Howes & Co., of Mark Lane, and shown in Fig. 123. This little machine goes in very small compass, and has a double sieve to take out large and small impurities by a powerful aspiration. The floor space it occupies is only about 15 in. x 40 in. Working with a plant of this description, any wheat may be taken weighed, and milled either with or without conditioning. Its comparative behaviour during milling can be observed, and the total yield of flour deter- mined. Finally the quality of the flour can be tested against, and com- pared with that of, flour milled from the standard mixture on the same machine. 931. Replacement Calculations. — ^In making wheat replacements, the following is a very common occurrence. Given a wheat strong in one con- stituent (C), and another wheat weak in the same constituent (C), it is required to calculate the proportions of each that must be taken to give a mixture that shall have a desired intermediate percentage of C. Thus as an example, a wheat has been in use which has 4 per cent, of C. The only wheats that can be used to replace it are a stronger wheat in that particular respect, containing 5 per cent, of C, and a weaker one containing only 2 per cent, of C. In what proportions must they be used to give a mixture containing 4 per cent, of C ? Stronger wheat, S, contains 5 per cent of C. Weaker ,, W ,, 2 „ „ C. Alixture, M, is required to contain 4 per cent, of C. First calculate the quantity of each that will contain 4 parts of C. As 5 (of S) is to 4 : : 100 : 80 As 2 (of W) : 4 : : 100 : 200 Therefore, 80 parts of S will contain 4 of C. . 200 „ W „ „ 4 of C. and 100 ,, M must ,, 4 of C. Call the quantities that will contain the amount of C in M as just indi- cated, QS, QW, and QM. Then QS (QW — QM) = amount of S to be taken. andQW(QM-QS) = „ W „ Thus QS (QW-QM) = 80 (200 — 100) = 8000 parts of S to be taken, and QW (QM-QS) = 200 (100 — 80) = 4000 parts of W to be taken. Then 8000 parts of S contain 400 of C. and 4000 „ w „ 80 of C. 12,000 „ M 4*^ of C. and 100 „ M 4 of C. Of the stronger wheat, therefore, 8 parts must be taken, and of the weaker, 4 parts ; or yet more simply in the proportion of 2 to 1 . The following is a somewhat more difflcult example : — S contains 4-3 per cent, of C. W „ 1-9 „ „ C. M to contain 2-7 ,, ,, C. As 4-3 : 2-7 : : 100 : 62-8 = QS. „ 1-9 : 2-7 : : 100 : 142 1 = QW. Then QS(QW-QM) = 62-8(142-l-100) = 2643-88 of S. „ QW (QM-QS) = 142-1(100 -62-8) = 5286-12 of W. 850 THE TECHNOLOGY OF BREAD-MAKING. As S contains 4-3 per cent, of C, 2643-88 of S contain 113-68 of C. „ W „ 1-9 „ „ C, 5 286-12 o f W „ 100-40 of C. 7930-00 of M „ mT 08 of C. As 7930 : 100 : : 214-08 : 2-7 = desired percentage of C. An inspection of the composition of the mixture shows that it contains as nearly as possible 1 part of the stronger wheat to 2 parts of the weaker one. In percentages, the result works out thus : — As 7930 : 100 : : 5286-12 : 66-66 per cent, of W. 100-66-66 =33-34 „ „ S. 932. Use of Improvers. — ^When any system of artificially inproving flours is in operation, the duty of checking and controlling the same will naturally fall to the chemist whether working in or out of the mill. In the case of the use of a bleaching plant, the miller Avill exercise his own judg- ment as to the extent of the bleach he requires. The chemist should com- pare the reactions of the bleached with the unbleached flour and see that no essential of the flour undergoes any material alteration. In event of the employment of any process of saline or other treatment, whether by direct addition, spraying, or otherwise, more exacting chemical duties are required. The proportions of saline constituents, sugars, and amylolytic and proteolytic enzymes in what has been called the mill’s standard flour should be carefully estimated. It should also be ascertained whether any flours which are below standard show any great deviation in any of the foregoing particulars. Experiments should be made in order to determine whether the addition of these deficient bodies improves the quality of the flour, and if so to what extent they should be added. The object of all these tests is to formulate some definite scheme for the addition of these agents to the flour of each individual mill. Some such data having been acquired, the experimental flours of new wheats should be tested vdth and without the improving addition, and the system of adding or not adding any improver carried out on a scientific basis. It must be borne in mind that the object of all these additions is simply to remedy the natural defi- ciencies of some wheats and thus place them on the level normally attained by other wheats without any addition whatever. Important responsi- bilities are thus cast on the chemist, as non-addition is in some cases as- necessary as addition is important in others. 933. Baking Tests. — Not only the control of the testing mill, but also that of the mill’s baking tests will probably be within the functions of the chemist. It will be more especially his duty to see that conditions of exactitude, both as to quantities and modes of working, are secured. He A\'ill also see that the baking methods used represent as nearly as possible those under which the flour is baked commercially, and will inspect the baked loaves and keep a record of their properties. Under certain circumstances it may be necessary for him to make a more or less complete analysis of the l)aked bread. 934. Summary of Chemical Functions in Mill. — ^The preceding para- graphs contain an outline of suggestions as to the adaptation and organisa- tion of chemical functions to milling routine. They apply equally to the performance of such work in the mill or in the laboratory of some outside specialist. The suggestions have not been made too definite, because after all each particular mill’s set of problems must be worked out by the chemist to whom they are entrusted. As to the utility of such tests, it must be re- membered tliat the chemical aspect of Avheat quality may now be regarded as fairly settled on a scientific basis, and questions involving chemical investi- EOUTINE MILL TESTS. 851 gation must continually arise in practical milling if the best results are to be obtained with the greatest commercial success. There is a certain amount of healthy rivalry between what may for convenience be called “ chemical ” and baking tests on flour. Each has its own merits, but a frequent criticism is that “ baking is after all the final test of flour.” To this no open-minded chemist will demur, but he will like- wise know that his own work also throws most important light and guidance on milling. And this light and guidance are usually of a kind which baldng tests are absolutely unable to furnish. It is frequently astonishing to note how in regular routine testing of flours the chemist on observing some depar- ture from the normal is able to predicate successfully an alteration in the quality of the flour. And the importance of the knowledge thus fur- nished lies in the fact that it is not merely the observation of a result, but is based on the discovery of the cause. As to the value of chemical work as applied to milling, the following testimony from the Ogilvie Flour Mills Co., Ltd., who were among the pioneers in this direction, cannot fail to be of interest : — “ I would say that in the operation of mills of large capacity such as we control, our experience has been that laboratory work is one of the absolute essentials to successful and economical operation, and an actual necessity for the maintenance of a uniform product of high quality. We certainly would not for one moment think of dispensing with this feature of our business.” [Personal Communication, April, 1908.) One last suggestion may be respectfully made to those who may decide to enlist chemical assistance in their milling operations, and that is to have patience and not expect too much at the commencement. The first task of any chemist will be to thoroughly familiarise himself with all the pro- perties of the particular mill’s flour, formulate standards on the lines indi- cated, accumulate data, and generally study the whole chemical aspect of the problem before him before he makes or suggests any radical alterations. This takes time, but the work having once been done, his recommendations have the merit of being not simply speculative, but based on a reasonable degree of certainty. Further, the introduction of the new wheel in the machinery is not keenly welcomed by those already responsible for its general running. In certain cases the present mill foremen, testing bakers and others have keenly resented what they regard as the intrusion of the chemist. It is to be feared that under such circumstances, even if no active steps are taken to nullify the recommendations of the chemist, no great amount of assistance is rendered in the direction of carrying them into effect. Much will here depend on the tact of the chemist himself, and he can do much by taking the stand that his functions are not to replace or displace those who occupied the responsible positions before him, but rather to co-operate with and assist them. It is a truism to say that the miller can make a good sack of flour, whereas the chemist qua chemist cannot ; but if the miller and the chemist, by working heartily in unison, can make a better and cheaper sack of flour than can the former alone, then the milling chemist has justi- fied his existence. This phase of antagonism and suspicion has to be lived down, and the chemist requires at this stage all the moral support that can be afforded him by his employer. CHAPTER XXXIII. CONFECTIONERS’ RAW MATERIALS. 935. Flour Confectionery. — ^Under the general term confectionery are included articles of such a widely diversified nature, that some sub-division is necessary. It is a convenient classification to include in one group those goods of which the cake may be taken as a type, and into which flour enters as an essential constituent, and call them flour confections. The second group may then include those goods of which sugar is the basis, and which may be viewed as sugar confections. The present work attempts to deal principally with the raw materials of the first or flour group. Incidentally, some explanation will be afforded of the chemical changes underlying certain confectionery manufacturing processes. A good deal of the matter of this chapter formed the subject of a course of Cantor Lectures delivered by one of the authors before the Society of Arts. The authors’ thanks and acknowiedgments are due to the Society for placing at their disposal the report of the lectures, which appeared in its Journal. 936. Flour. — ^The composition and properties of flour have already been dealt w ith so exhaustively, that but little further reference is necessary at this stage. In bread- making, the baker will naturally prefer a flour with a high absorbing power, since all else being equal, the cost of making dough Avith a larger percentage of w^ater is obviously less. But with the con- fectioner, the moistening ingredients are in most cases more expensive than his flour, and consequently it is to his interest to use a flour which shall obtain its desired degree of moistness wdth the minimum of these more expensive materials. Further, the w'eaker and softer flours lend them- selves more readily to the manipulation and working necessary, than do those of stronger nature. It should also be noted that in bread-making, the flour during the operation of fermentation undergoes considerable softening, wiiile no similar changes occur in the manufacture of confectionery. For these various reasons, therefore, the confectioner usually selects a weak and somewhat soft flour containing much starch and comparatively little gluten, Avhicli latter should be of a soft, ductile, and silky character. For the sake of the colour of the cakes or other manufactured goods, a flour of a wFite or delicate creamy tint is preferred. xAmong flours used by the confec- tioner, and answ^ering more or less to this description, are finest flours from Englisli wheats, Hungarian flours, and those from the softer wFite wheats of North America. Moistening Ingredients. 937. Milk. — ^As a cake moistening ingredient, milk holds a very prom- inent place, and requires a somewhat extended reference. There is prob- ably no substance of which so many analyses have been made, as milk, and consequently, its composition and variations of composition, are well known. Milk is used by the confectioner in at least three distinct forms — new milk, skim or separated milk, and sour separated milk. This latter is 852 CONFECTIONERS’ RAW MATERIALS. 853 at times supplied mixed with butter-milk, and has special uses, to which reference wull again be made. The following table, based on the authority of Vieth and Richmond, gives the average composition of pure new milk : — Fat . . Proteins Sugar Ash . . . . 3 6 . . 4-5 .. 0-7 4 0 Total Non-fatty Solids . . — 8-8 Water 87*2 100 0 By the removal of fat the percentage of other solid bodies in milk is slightly increased, and separated milk has about the following average composition ; — Fats . . .. 0-3 Proteins . . 3-7 Sugar 46 Ash .. 0-7 Total Non-fatty Solids . . 90 Water . . 90-7 100 0 The fat of milk, like that of other fats, confers richness on cakes, and will be dealt with in detail subsequently. The sugar present in milk is a special variety, to which has been given the name of lactose. Lactose, or sugar of milk, is represented by the formula, C 12 H 22 O 11 , and has therefore the same composition as cane sugar and maltose. It is not, however, iden- tical with either of these bodies. Lactose differs from cane sugar in that it is far less sweet, and hence is not such a powerful flavouring agent as sugar of the latter description. The remaining constituent of milk of im- portance to the confectioner is the protein matter. This last has, like the white of egg, no very pronounced taste, but yet its presence confers on milk a fulness and roundness of flavour (if phraseology may be borrowed from other tasters’ vocabularies) which a simple solution of lactose in water would not possess. In the baked goods, the protein of milk produces a moistness and mellowness of character, which decidedly differs from that caused by water only. Summing up, new milk gives richness through its fat, sweetness through its sugar, and what for lack of a better term, may be called “mellowness ” through its proteins. Separated milk is practically new milk less its fat. 938. Milk Standards. — ^The composition of mflk has been indicated in the analyses already quoted, but these figures are not by any means the lowest obtainable from undoubtedly pure samples of milk. For purposes of the Food and Drugs Adulteration Acts, the limits have been adopted of 3 per cent, of fat, and 8*5 per cent, of non-fatty solids. But for confec- tioners’ purposes, a direct estimate of value is of more importance than knowing whether or not a particular sample of milk passes the limits of the pubhc analyst. Thus milks containing respectively 3 and 4 per cent, of fat, would, so far as the fat is concerned, be passed as free from adulteration ; but evidently the former sample has only three-fourths the fat value of the latter. For some years this subject of the valuation of milks has en- 854 THE TECHNOLOGY OF BREAD-MAKING. gaged the attention of one of the authors, who suggests, and has for some considerable time employed a standard of valuation worked out on the following lines : — From an examination of a large number of commercial milks an average conventional standard of quality was first determined, the aim being not to go so low as the Government limit for adulteration, but to take figures which a buyer might reasonably demand to be reached in milks supplied to him. These were ultimately taken as being for New Milk. Separated Milk. Total Solids. . . . 12-5 9-3 Fat . . 3*5 0-3 Non -fatty Solids . . . . 90 9 O’ The figure, 9-0, is in reality somewhat too high for the non-fatty solids of an average new milk, but in order to make the comparison between new and separated milk as simple as possible, the same figure has been adopted for each. The difference between 9-0 and the more correct figure, 8-8, does not practically affect the valuations. At the time when these figures were adopted, the approximate whole- sale prices of milk were, new, \0d. per gallon ; separated, 2\d. per gallon. New milk differs essentially from separated in that it contains an excess of 3-2 per cent, of fat. According to the wholesale prices this excess of fat lias a market value of 7-5c?., and in the same proportion 3-5 per cent, of fat is worth ^-'2d. From this the value of conventional standard samples can be expressed in terms of their constituents ; — New Milk. Separated Milk. Fat 3-5 = S’2d. .. 0-3 = 0-7t^. Non-fats .. .. .. 9-0 = l-8c?. .. 9-0 = l-8c?. per gallon . . . . 10 -Ot/. 2-5d. Obviously other prices can be assigned to new and separated milks and the values of the constituents similarly calculated. If the value of standard new milk be called 100, then the value of any other sample can from the analysis be expressed in terms of percentages of the standard from the following Table : — Valuation of Milks. Fat in Terms of Standard, Fat Percentage of f Fat Percentage of Fat Percentage of per cent. Standard. per cent. Standard. per cent. Standard. 0-1 — 2-34 1*7 — 39*83 3*3 zi: 77*32 0-2 — 4-69 1*8 42*17 3*4 79*66 0-3 — 7-03 1*9 44*52 3*5 — 82*00 04 — 9-37 2*0 46*86 3*6 — 84*34 0-5 — 11*71 2*1 49*20 3*7 — 86*68 0*6 r= 14*06 2*2 = 51*55 3*8 89*02 0-7 16*40 2*3 53*89 3*9 — 91*36 0-8 18*74 2*4 56*23 4*0 = 93*70 0-9 =r 21*09 2*5 58*57 4*1 nr 96*04 1-0 = 23*43 2*6 60*92 4*2 — 98*38 M 25*77 2*7 63*26 4*3 =Z 100*72 1-2 — 28*12 2*8 65*62 4*4 — 103*06 1-3 — 30*46 2*9 67*95 4*5 nr 105*40 14 — 32*80 3*0 70*29 4*6 nr 107*74 1-5 .35*14 3*1 72*63 4*7 nr 110*08 1-6 37*49 3*2 = 74*98 4*8 nr 112*42 CONFECTIONERS’ RAW MATERIALS. 855 Non-Fatty Solids in : Terms of Standard. Non-Fatty Percentage X'on-Fatty Percentage Non-Fatty Percentage Solids of Solids of Solids of per cent. Standard. per cent. Standard. per cent. Standard . 4-8 9-6 64 = 12-8 8-0 =z: 16-0 4-9 = 9-8 6-5 z= 13-0 84 = 16-2 5-0 — 10-0 6-6 = 13-2 8-2 164 5-1 = 10-2 6-7 134 8*3 16-6 5-2 104 6-8 nr 13-6 84 = 16*8 5-3 10-6 6-9 = 13-8 8-5 z=; 17-0 54 ZIZ 10-8 7-0 =: 14-0 8-6 z= 17-2 5-5 = 11-0 7*1 =z 14*2 8*7 1= 174 5-6 11-2 7-2 — 144 8-8 = 17-6 5-7 114 7-3 14-6 8*9 z= 17-8 5-8 11-6 74 :z= 14-8 9-0 18-0 5-9 11-8 7*5 := 15-0 94 — 18-2 6-0 =z 12-0 7*6 z= 15-2 9*2 =Z 184 6-1 12-2 7*7 = 154 9-3 — 18-6 6-2 = 124 7-8 = 15-6 94 =Z 18-8 6-3 = 12*6 7-9 15-8 9-5 19-0 In the Table on page 856 are given the results of analysis of some typical examples of milk, their values in terms of standard and per gallon, assuming standard milk to be worth lOt?. per gallon. Attention is drawn to the fact that milk No. 7, although of highest value in terms of standard, shows, nevertheless, evidence of having been watered, and would probably be made the subject of a prosecution if analysed for the purposes of the Foods and Drugs Acts. The public analyst is con- cerned simply with adulteration, while the commercial user is more vitally interested in the Cjuestion of actual value. A gallon of milk weighs approximately about 10-3 lbs. or 10 lbs. 5 ozs.^ and if this be bought at 10c?., the purchaser gets, if the milk is of standard value, 0-36 lbs. = 5-76 ozs. of butter fat, for which he pays 8 -26?., or at the rate of 2'2-ld. per lb. ; and 0-93 lbs. = 14-88 ozs. of mixed protein^ milk-sugar, and ash ; for which he pays l-8(i., or at the rate of l-9c?. per lb. A gallon of separated milk of standard value weighs about 10-5 lbs. or 10 lbs. 8 ozs., and if this be bought at 2Jc?., the purchaser gets 0-03 lbs. = 0-48 ozs. of butter fat and 0-945 lbs. = 15-1 ozs. of mixed protein, milk- sugar, and ash, making 0-975 lbs. of total solids, which he buys at the rate of 2’56d. per lb. Taking butter, containing 87 per cent, of butter fat, at Is. per lb., then — One gallon of separated milk, costing . . . . 2^d. And 0’33 lbs. of butter, costing . . . . . . 4Jc?. Together costing . . . . . . . . 7c?. will yield the equivalent in quantity of the total non-fatty solids, and butter- fat of one gallon of new milk costing 10c?. 939. Condensed Milk. — Condensed milks of the unsweetened variety are at times employed instead of new^ or separated milks. In ascertaining the value of these, it is well to dilute them to three times their original volume. Then such a milk as No. 9 is, as nearly as possible, of the same degree of coifcentration as standard milk. One gallon of such milk, in the concentrated form, is worth, as against standard milk, 9-8 X 3 = 28 •4(?. per gallon. 856 THE TECHNOLOGY OF BREAD-MAKING. No. Description of Milk. i Com- position. Value in terms of Stand- ard. Value per Gallon. 1 Milk with 26 per cent, of added water ( Fat . . . . ( Solids not fat ’ 3-2 ()-6 74-98 13-20 9-8 88-18 8-8d. 2 Milk deprived of 40 per cent, of its cream (Fat . . . . 1 Solids not fat 1-8 91 42-17 18-20 1 10-9 60-37 6-Od. 3 Old Somerset House limit, below which I Fat . . . . 2-5 58-57 milks were considered adulterated 1 Solids not fat 8-5 17-00 11-0 75-57 7-5d. 4 Present Government limit (Fat . . . . i 1 Solids not fat 3-0 8-5 1 1 70-29 17-00 11-5 87-29 8-7d. 5 Author’s conventional standard f Fat . . . . ] Solids not fat 3-5 9-0 82-00 18-00 12-5 100-00 10 -Od. 6 Average composition of pm’e new milk ( Fat . . ( Solids not fat I 4-0 ‘ 8-8 1 93-70 17-60 12-8 111-30 1 11-ld. 7 Very rich milk slightly watered (Fat . . ( Solids not fat 4-3 ^ 8-1 100-72 16-20 12-4 1116-92 11 -7d. 8 High quahty sample of skimmed milk ( Fat . . t Solids not fat ' 0-4 1 9-1 9-37 j 18-20 9-5 27-57 2-7 ad. 9 Unsweetened condensed milk diluted to ( Fat . . 3-5 82-00 three times its volume . ] Solids not fat ! 8-2 ! 16-40 11-7 I j 98-40 9-8d. 10 Unsweetened condensed milk diluted to ( Fat . . ; 2-0 1 46-86 three times its volume , t Solids not fat 8-6 i 17-20 10-6 i 64-06 6-4d. No. 10 has been deprived, before condensing, of nearly half its fat, and con- sequently is only worth 6-4 X 3 = 19-0(^. per gallon. Such condensed milks may not only be diluted and used as moistening agents, but also at times are employed in their concentrated state, as a more or less complete substitute for butter. These condensed milks have, or should have, an approximate density of IT, and therefore a gallon of No. 9 will weigh about 11 lbs., and is worth, on the milk standard, or 2 - 58 ( 1 . per lb. A gallon of the milk will contain, roughly, 2-70 lbs. of non- fatty solids, and 1T5 lbs. of butter fat. . This is the equivalent in quantity CONFECTIONERS’ RAW MATERIALS. 857 •of 2-85 gallons of separated milk, at a cost of 7Td., and 1-32 lbs. of butter which at Is. per lb. costs 15-8(i., or a total of 22-9d. Unless, therefore, such full value milk as No. 9 is bought at 2-OSd. per lb., its proteins, milk- sugar and fat, can be more cheaply supplied from separated milk and butter. 940. Milk Powders. — ^By modern processes, milk is now reduced to the condition of a dry powder, and is an article of sale containing only a very • small percentage of moisture. Full cream, half cream, and separated milk powders are now on the market. In the absence of moisture, these bodies -have the following approximate composition : — Composition of Milk Powders. Constituents. Full-cream. Half-cream. Separated. Fat 31 *2 17-2 3-2 1 Proteins 28-1 34-0 .39-8 Sugar . . 35-2 42-3 49-5 Ash 5-5 6-5 7-5 100-0 ! 100-0 i 100-0 Weight of water required to convert 1 lb. of each into liquid of the same strength as milk . . 7-8 lbs. 9-3 lbs. 10-7 lbs. One pound of the full-cream powder is equivalent in butter value to about 5| ozs. of butter ; in addition to which it contains proteins and sugar in approximately the same quantities. On mixing the powders with warm water in the proportions given above, a fluid corresponding to the original milk is produced. 941. — ^Eggs. — ^Next to milk, eggs are one of the most important moisten- ing agents to the confectioner. The raw white of egg is a viscous glairy liquid, the yolk being somewhat more fluid in character. In composition, the white of egg consists of protein matter dissolved in water, while the yolk contains in addition to protein, fat and colouring matter. The follow- ing table gives respectively the results of analysis of the white, yolk, and whole interior of the egg : — Constituents. White. Yolk. White and Yolk together. Water 85-7 50-9 73-7 Protein . . 12-6 16-2 14-8 Fat 0-25 31-75 10-5 Ash 0-59 1-09 1-0 The white of egg may be viewed as a solution of one part of albumin in seven parts of water, while in the whole egg about two -fifths of the solids consist of fat, and three-fifths of protein matter. The water of the whole egg amounts roughly to three-quarters of its weight. Or putting it another way, 1 lb. of whole eggs contains about 4 ozs. of solids, and I lb. of white of egg just half that quantity or 2 ozs. When either of these are used in making 858 THE TECHNOLOGY OF BREAD-MAKING. a dough with flour, the w ater part of the egg does the moistening, and acts in the same w ay on the constituents of flour as w'ater alone w'ould do. The wiiite, if used alone, is so nearly tasteless that it cannot be said to confer any very decided flavour ; but, as w^as remarked with regard to the protein matter of milk, it imparts the property described as that of niello wmess to goods in whose manufacture it is used. The yolk, on the other hand, is very marked in flavour, and just as eggs themselves are in consequence most pleasant eating, so cakes have a remarkable richness of flavour caused by the yolks of eggs used in their manufacture. The yellow of the yolk confers its distinctive colour on the cakes and other goods in which it is employed ; as a consequence the full yellow of a cake has become associated with the idea of its richness. With cakes made at very low' prices, the use of eggs in full proportion becomes an economic impossibility, and therefore, in the cheaper cakes, an effort is made to please the eye by adding artificial colouring matter. The nature and composition of the substances used for this purpose are described in a subsequent paragraph. 942. Dried Egg Whites. — ^For certain purposes, in place of the wLite of eggs, the confectioner has offered to him such w'hites as desiccated albumin. This preparation should consist of the pure fresh wLite of egg evaporated dow'n to dryness at a temperature w'ell below' that of the coagulation or setting of albumin. Such dried albumin should soften on tlie addition of W'ater and form a solution possessing the same properties as fresh w'hite of egg. The solution should be free from any unpleasant taste or odour of decomposition. As w'hite of egg contains one-eighth its w'eight of pure albumin, it follow'S that dried egg-albumin should, everything else being equal, be worth w'eight for w'eight eight times as much as fresh w'hite of egg. In other words, pure egg-albumin at anything below eight times the cost of white of egg is economically to be preferred to such fresh w'hites. The objections to such commercial albumin are first, that it may be partly coagu- lated, and second, that it may be unpleasant in odour or taste either as the result of preparation from unsound eggs, or incipient putrefaction during its manufacture. Among adulterants, to which dried egg-w'hites are subject, are dextrin, sugar, and gelatin. Serum- or blood-albumin, is less expensive than egg-albumin, and so may possibly be substituted for it w'ithout declara- tion to the purchaser. The table on the follow'ing page gives the results of analysis of a number of samples of dried egg-whites, together w'ith that of fresh w'hite of egg taken for comparison. A 5 per cent, solution of the pow'dered albumin in cold w ater was prepared and filtered through paper. The total solid matter, and nitrogen by Kjeldahl’s method, w'ere determined on the filtrate. Another portion of the filtrate w'as acidulated with acetic acid, and boiled so as to coagulate the albumin, which was in turn filtered off. The re^ sidual soluble matter and nitrogen w'ere then determined in the second filtrate. In each case the nitrogen multiplied by the factor 6-25 gave a ([uantity which did not amount to as much as the total matter present. The difference is therefore returned as non-nitrogenous matter. The samples 1 , 2, and 3 w'ere specimens of commercial dried egg-whites : 635 Silicic acid 38 Silicon, silica, and the silicates . 38 Simple proteins .... 96 Smoke nuisance . . . .590 Smut 195 Soaps and Fats .... 49 Sodium bicarbonate . . . 464 Sodium chloride PAGE 400 — compounds .... 40 Solid and flash heats . 429 Solids, Solution of . 23 Soluble ferments 121 — proteins .... . 294 of wheat .... 100 — extract .... 296, 768 — starch 81 , Estimation of . 818 Solution 22 — , Gaseous .... 22 — of liquids .... • 23 — of solids .... 23 Sour bread • 433 , Briant’s researches on . • 434 , Researches on • 437 , Remedies for . • 450 , Separation and identification of acids of . . . . 438, 774 , Summary of views on . . 449 Souring of bread. Ammonia pro- duced during .... 447 , Effect of high tempera- tures on 447 Sourness, Relation of, to acidity 434, 447 attenua- Soxhlett’s extraction apparatus Special breads and bread-making processes . Specific heat — gravity of worts and tion . — rotatory power . Spirits of wine, alcohol , Methylated Sponging and doughing by machinery Sponge — and dough . , Management of Sponge-making machines Spontaneous fermentation Sporangia Spores Spraying treatment of wheaten stock and flour Stability of flour tests “ Standard ” bread .... , Snyder on ... . Starch — , Action of caustic alkalies and zinc chloride on — , Action of diastase on — , Action of iodine on 763 483 5 . 247 . 807 44 . 46 . 425 . 637 . 402 404. 425 . 426 . 644 . 191 . 192 . 185 498 705 553 561 77 . 294 82 127 82 — , Admixture of, with yeast . . 239 — , bruised, Action of malt extract on 129 — cellulose 77 — , Estimation of . . . 814,816 — , Fermentation of ... 206 — , Gelatinisation of . . 80, 89 — , — , Temperature of . . , 81 — grains. Effect of size of, on flour, Armstrong 321 — , Hydrolysis of . . . 139,143 — in yeast .... 239, 840 — , Molecular constitution of . . 130 — , Occurrence of . . . . 77 — of wheat .... 77, 78, 79 906 INDEX. PAGE PAGE Starch paste, Action, of malt extract Tcxalbumins .... 224 on . 129 Transmission of heat 8 — , Preparation and manufacture of 80 Treacle ..... 872 — , Properties of, in solution 82 Trimethylamine SI — , Saccharification of . . . 120 True gluten .... 296 — , Solubility of ... . 80 , Estimation of 783 — , Soluble 81 — proteins. Estimation of 784 — , — , Estimation of . . . 818 Trypsin 138 — solution. Properties of 82 Tuberin 97 , Reactions of . . . 82, 89 Turog bread .... 487. 493 — sugar, glucose .... 876 Tyrosine 54 — , ungelatinised. Action of malt extract on 128 Starches, Microscopic character of 1 1 various 77 U — , — examination of . . 88.^21 Steam oven 659 Underground bakehouses . 582 Stearic acid 49 Unsound, or very low grade flours. Storage of flour. 629 Working with . , 459 Strength of flour . 29 1 , 294, 3 1 1 , 3 1 9 Ustilago segetum 195 yeast 198 “ Strengthening ” flours 374 Striking gear ..... 624 V Substitution, or compound, ammonias 54 Succinic acid 50 Vacuum oven .... 693 Sucrose, cane sugar . . . 85, 871 Vanilla and vanillin . 889 Sugar and dextrin of wheat . 294 Vanillin, Synthetic . 890 — boiling 874 Veda bread. Analysis of . 495 — , cane, inverted, Polarimetric Vegetable albumin . 96 behaviour of ... . 811 — myosin 97 . 99 — , Cutting the grain of . 875 Veltex 869 — , Fondant 875 Vernier, Description of . 810 — , Polarimetric estimation of 811 Vibrio suhtilis .... 185 Sugars 294,871 Vienna bread .... 461 — , Commercial, Composition of . 872 — ovens 668 — , Estimation of, by Fehling's Viennara kneading machine . 641 solution 800 Virgin, barm .... 249 — , — — , by polarimeter 811 Viscometer .... 702 Sulphates 37 — , Mode of testing with . 703 Sulphites 37 Viscometric gluten valuations 298 Sulphur 37 Viscous fermentation 191 — dioxide 37 Vitellin 94 . 97 Sulphuretted hydrogen . 37 “ Volatile,” ammonium carbonate 464 Sulphuric acid and sulphates . 37 Voller on wheats 282 Sulphurous acid and sulphites 37 Voller’s dictionary of wheat . 284 Symbols and formulae 12 Volume, Laws of chemical com- Systeme-Schweitzer of bread-mak- bination by . . . 15 ing 483 — , Measures of . 25 T Tailings, Composition of . 345 . 351 Tannin, Effect of, on bacteria . 190 Tartar, Cream of . . . . 464 Tartaric acid .... 50. 464 Tartrate powders . 467 Telegraphic codes . 845 Temperature .... . 2 — , Absolute zero of 7 — , Automatic regulator . . 227 — , Effect of, on fermentation . 214 Test mills . 691 Testing with viscometer . 702 Thermometer .... 3 Thermometric scales 3 Tintometer .... . 709 Total proteins. Estimation of . 780 Tourmaline .... 66 W Walsh and Waldo on effect of bak- ing on bacterial life . . 450 Wash-bottle .... . 761 Water 29, 400 — bath 227, 769 — , Corrosive action of . . 637 — ■, Estimation of . • • . 691 — for washing wheat . 361 — free from carbon dioxide . . 772 — heating . . . 675 — in furnace ashpit . 674 — Measuring and attemperating :or tempering ...» . 636 — of wheat .... 297, 691 — , Softening of . • • . 400 — , Solvent power of 29 INDEX. 907 PAGE Water-absorbing power of flour 345, 699 , Effect of temperature on 706 Water-absorption burette . . 700 Watkins on ropy bread . • -452 Weighed filters .... 763 Weighing of bread . . • 562, 648 — , Operation of . . • .685 Weight, Measures of . . • 25 Weights, Analytic . . • .683 — and measures, English . . 27 Weyl and BischofE on wheat pro- teins 99 Wheat, Agricultural improvement of . . . • • -497 — ash. Composition of . • 69, 270 — blending . . • • • 473 — , Chemical changes during ripening of 282, 290 — , Chemical composition of . . 207 — , Cleaning machine for testing . 849 — ’ Commercial assay of . . .307 — , Constituents of . . 68,73,270 — , Damping of . . . • • 360 — , Distribution of gluten in . . 370 — , Durum, Norton .... 280 — , Fatty matters of . • 70, 294 — , Foreign matters in . . . 690 — , Germination of . . • • 267 — grain. Construction of . 68, 254 , Crease of . . • .256 , Functions of . . . 254,559 — Grinding of samples . . . 690 — , Insoluble proteins of, gluten 105, 1 19, 296, 305, 343 — , Microscopic examination of . 258 — , Mineral constituents of . .68 — mixtures, Voller . . . .282 — oil, de Negri, Frankforter, and Harding 7 1 — , Organic constituents of . • 7 ^ — products. Nutritive ratio of . 527 — , Protein of, soluble in dilute alcohol, gliadin . . • 310 A— proteins. Properties of, Cham- berlain 3^0 — replacement calculations . . 849 tests 847 — • section cutting . . . .257 — , Soluble proteins of . • .295 — testing 689 — , — Commercial, Snyder . . 307 — , Treatment of, by moist heat . 497 — , , by water-soluble phos- phates 497 — washing, Water for . . . 361 — . Water-soluble phosphates of. Wood 323 — , Weight per bushel . . • 689 — , — of 100 grains . . • 689 Wheaten stock, Spraying treatment of 498 Wheats, American . . • .728 — , Analyses of . ... 272 — and flours, Artificial drying of . 362 — , Artificial drying of . . • 361 — , Composition of, Fleurent . . 280 — , Damping of . . • • 369 — , English and Scotch . . . 273 \ Wheats, Foreign . . . . — , McDougall’s tests on. — , Replacing mixtures of White bread, analysis of . Whole meal bread .... — , Analysis of . • • Wild yeasts Wire ropes Wood on strength of flour Worts, Preparation of . • • — , Specific gravity of, and attenua- tion PAGE 276 279 282 495 470 495 179 628 311 236 247 X Xanthoproteic reaction of proteins 93 Y Yeast . . • • *150 — , Admixture of starch with . . 239 — an article of food . . • • 241 — and other organisms. Isolation of 167 — as an organism . . • -153 — , Ascospores of . . • 166,176 — , Bakers' home-made . . .241 — , Behaviour of free oxygen to . 160 — , Botanic position of . . • i 54 — , Bottom-fermentation species . 179 — , Brewers’ 233 — brewing, Suggestions on . • 246 — , Budding of 1 5 5 — cells, Nature of . . • *155 — , Chemical composition of . • 152 — , — reactions of . . • *155 — compressed, Characteristics of 239 — , — , Manufacture of . . *235 — counting ^3 — , cultivated. Varieties of . • I 79 — culture and isolation . . .167 — , Distillers’ ^72 — , — , Manufacture of . . • 235 — , Efiect of rousing on . . • 161 — , Endogenous division of . .166 — growth, Influence of tempera- ture on . . • . . I 58 — , High . . *.*..• • — ^ — and low, Convertibility of . 172 ’ , Distinctions between 1 70 — ’ Insufficiency of either sugar or nitrogenous matter only for nutriment of . . • .160 — , Isolation of . • • .167 — , Keeping properties of . 213,231^ — , Life History of . • • .156 — , Low or sedimentary . . .170 — , Mal-nutrition of . • .165 — , Manufacture of . . • .233 , bakers’ “ patent ” or home-made malt and hop • 241 — ^ brewers’ . . • • 233 — ^ compressed . • .235 ’ Scotch flour barm . . 249 ’ Methods of isolation of, and other organisms . . .167 908 INDEX. PAGE Yeast, Microscopic study of 1 8 1, 233, 248 — , Mineral matters necessary for growth of — mixture .... 203 — , Multiplication of, by endogenous division — , Nature of cells of . . . — , Necessity of saccharine matter for — , Nitrogenous nutriment of. “ Patent ” — , Formula for .... — , Suggestions on . . . Purification of . . . 167, 189 Sporular reproduction of . .166 Starch in 840 Strength of ig8 Substances requisite for nutri- ment of 158 160 230 166 155 158 159 241 246 246 Yeast, Technical researches on — testing ..... Apparatus — , Top-fermentation species of — , variety and quantity used Yeasts, Classification of . — , Detection of wild — , Hansen on analysis of Young on alum PAGE . 198 198, 229 199, 227 . 180 155.426 . 170 • 179 . 176 . 842 z Zein Zero, Absolute Zoogloea . . . . Zymase . . . . — theory of fermentation 97 7 183 139 148 L & A. Harris, Printers, 94, Leadenliall Str^, E.C,