Iisued June 30, 1913. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY.— Bulletin *65. A. D. MELVIN, Chief ok Bureau. THE MANUFACTURE OF CHEESE OF THE CHEDDAR TYPE FROM PASTEURIZED MILK. BY J. L. SAMMIS, PH. D., Associate Professor of Dairy Husbandry, College of Agriculture, University of Wisconsin, AND A. T. BRUHN, Expert Cheese Maker, Dairy Division, Bureau of Animal Industry. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1913. \mkch d Jun U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY.— BULLETIN 165. A. D. MELVIN, Chibf of Burbau. THE MANUFACTURE OF CHEESE OF THE CHEDDAR TYPE FROM PASTEURIZED MILK. BY J. L. SAMMIS, PH. D., Associate Professor of Dairy Husbandry, College of Agriculture, University of Wisconsin, AND A. T. BRUHN, Expert Cheese Maker, Dairy Division, Bureau of Animal Industry. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1913- THE BUREAU OF ANIMAL INDUSTRY. Chef: A. D Miiun Attittani Chief: A M I'm chief Clerk: I b uu i - C Cabbou Animal Butbandrff Division: Gi oboi M Rommel, chief. - on: M I »■ ►bsbt, i bief. Dairy Division: B 11 R I M i . « lii«'i'. Field Inspection R \ Ramsay, chief. Iftof Inspection R. P. Btbddom, chief. Pathological D n\ R MOHLEB, chief. Quarantine Division: Ki< BARD \\ . Ill* KMAN, chief. Zoological Division: B II RAN80M, chief. Experiment Station: E C. >< HBO] i»i ft, superintendent. r; Jambs M Pickens DAIRY DIVISION. B H Rawl, chief. Mm mkr Rabilp. in charge of Dairy Farming Investigations. 8 I THOMPSON, in charge of Dairy Manufacturing Investigations. I \ RoGl BS, >n charge of Research Laboratories. m charge of Market Mill: Investigation*. Robert McAdam, in charge of Renovated Butter Inspection. 2 LETTER OF TRANSMITTAL. U. S. Department of Agriculture, Bureau of Animal Industry, ^Yashington, D. C, January 30, 1918. Sir: I have the honor to transmit for publication as a bulletin of this bureau the accompanying manuscript entitled "The Manufac- ture of Cheese of the Cheddar Type from Pasteurized Milk, " by Prof. J. L. Sammis, of the College of Agriculture, University of Wisconsin, and Mr. A. T. Bruhn, expert cheese maker in the Dairy Division of this bureau. The work herein described was conducted at Madison, Wis., in cooperation between the Dairy Division and the Wisconsin Agricultural Experiment Station. The Dairy Division has been represented at Madison by L. D. Bushnell, Alfred Larson, and Miss Alice C. Evans, bacteriologists, in succession; S. K. Suzuki and E. F. Flint, chemists, and J. W. Moore, F. W. Laabs, and A. T. Bruhn, expert cheese makers, in succession, all of whom have assisted at various times in this work. The Wis- consin Station has been represented by Prof. Sammis, who from the beginning has had charge of the cooperative experiments in the manu- facture of the Cheddar type of cheese from pasteurized milk. The comparison of this cheese with that made from raw milk by the regular factory method has been systematically and thoroughly carried out under a variety of conditions by the use of duplicate vats of milk, one of these being pasteurized in each instance. During 1910 and 1911, especially in the latter year, the new process was per- fected and a large quantity of the pasteurized cheese was made under commercial conditions and placed upon the open market. The results are fully described, also the process of making the cheese, and it is shown that the use of pasteurized milk is highly satisfactory and economical. As pathogenic bacteria have been found to survive for several months in cheese made from raw milk, the pasteurization of milk in making cheese is also desirable for the protection of the health of the consumer. Respectfully, A. D. Melvin, Chief of Bureau. Hon. James Wilson, Secretary of Agriculture, CONTENTS Page. Introductory 9 The need for a new method of cheese making 9 Faults to be corrected in milk for cheese making 10 The necessity for the pasteurization of milk for cheese making 11 Amount of heat necessary to destroy various bacteria 12 Previous attempts to make cheese from pasteurized milk 13 Difficulties met in making cheese from pasteurized milk 14 Difficulties overcome by acidulation of pasteurized milk 15 The pasteurization process 18 Pasteurization in a discontinuous or " held ' ' pasteurizer 18 Continuous and ' ' held ' ' pasteurization compared 18 Selection of best temperature for pasteurization in the continuous machine . 20 Objections to higher temperatures than 160°-165° F. for pasteurization 23 Effect of pasteurization on the properties of cheese curd 25 The different types of continuous pasteurizers used 28 The acidulation process 28 The standard acidity of milk for cheese making 28 Comparison of different kinds of acid for cheese making 30 The proportion of hydrochloric acid required daily 30 Testing milk for acidity 31 Preserving the tenth-normal solution 32 Diluting normal alkali to tenth-normal 32 Adding acid to milk after pasteurization 33 Calculating the amount of acid to be added 33 Preparation of normal hydrochloric acid in the cheese factory 35 General directions for pasteurizing and acidulating milk 37 Making ready to pasteurize 38 Starting and stopping the pasteurizer 39 Starting and stopping the acidulator 40 The use of bacterial starter in the new process 40 The reason for adding starter in making pasteurized-milk cheese 40 A practical sterilizer for the cheese factory , 42 Preparation of the starter 43 Method of making cheese by the new process 45 General arrangement of schedule 45 Uniform proportion of color used in 1911, and rennet required 46 Adding starter, color, and rennet to the milk 47 Cutting, stirring, and heating the curd 48 Drawing the whey, matting, cutting, and turning the curd 49 Milling, salting, and hooping the curd 49 Pressing and dressing the cheese 50 Drying, paraffining, and curing 50 Branding and selling the cheese 51 Testing cheese for moisture when dressed in the hoop 52 5 CON Page. tS Of tWO J ears' trial of the new method 53 In. i.m-.'I \ it-lil i.i < h. •»•<«• .,1,1a i i m-« 1 l.\ the D6H | 53 Apparatus and methods of stud) 53 Sean 1 1 i'..r 13 sternal i«- erron in experiments on \ Laid of cheese Shrinkage before paraffining, and yield of paraffined cheese Shrinkage and > teld of cured cheese 62 The causae of the increased j ield Erom pasteurized milk »,!< Til.- Lossse "i ia i Erom vat and prees The increased moisture content ol pasteurized-milk i 73 Tin- quality <>i pasteurized-mili cheese ad criticisms of pasteurised and raw milk cheese Cheese cured at Madison at normal temperature 7.'. Cheese cured in tin- South t 79 tired in warm room at Madison 84 Cheese cured in cold storage 85 Exceptional differences between the raw and pasteurized milk cheese. 86 Summary of discussion of -'ores 87 The demand for pasteurized-milk cheese 88 I » pinions of purchasers 89 The extra cost of making pasteurized-milk cheese 89 Further trials of the new process in cheese factories 90 Summary 00 Preliminary and comparative work with the old and new methods 90 Sum.- advantages Erom the use of pasteurized milk and hydrochloric acid.. 02 Outline of the new method 93 ILLUSTRATIONS. PLATES. Page. Plate I. Outfit used in testing milk for acidity (Manns's acid test) and in testing strength of hydrochloric acid used in cheese making 32 II. The continuous disk pasteurizer, and apparatus used in acidulating pasteurized milk 32 III. The continuous "flash " pasteurizer, and apparatus used in acidulating pasteurized milk 32 IV. Transferring acid from full to empty carboy by means of siphon 36 V. Vat strainer for straining milk into receiving vat 36 VI. A uniform layer of curd, showing use of curd gauge 48 TEXT FIGURES. Fig. 1. A combined sterilizer, cooler, and incubator for cheese-factory starter.. 43 2. Method of marking cheese 52 3. Distribution of total scores of pasteurized and raw milk cheese 78 4. Distribution of flavor scores of pasteurized and raw milk cheese 78 5. Distribution of texture scores of pasteurized and raw milk cheese 79 6. Distribution of total scores of pasteurized and raw milk cheese 81 7 Digitized by the Internet Archive in 2012 with funding from University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation http://archive.org/details/mancheOOusde THE MANUFACTURE OF CHEESE OF THE CHEDDAR TYPE FROM PASTEURIZED MILK. INTRODUCTORY. THE NEED FOR A NEW METHOD OF CHEESE MAKING. Economy of time and labor and improved quality and uniformity of the cheese produced make the large cooperative factory more profitable to farmers than the small factory, provided they retain the control, if not the complete ownership, of it. There are two objections sometimes raised against the replacement of four or five small cheese factories in a neighborhood by one large, better- equipped, better-manned, and more economical cheese factory, namely: First, that by present factory methods cheese makers could not make as good cheese from milk gathered over a large territory, because it would be longer on the road to the factory and therefore would not be so fresh as otherwise; second, farmers object to haul- ing milk a great distance, even to a good cheese factory. The only way to get a large, first-class cheese factory located within a short distance of a sufficient milk supply is to centralize the latter — that is, to keep as many of the best cows on every farm as the land will support. Until this is done there will be many factories which must draw milk from a large area. Some modification of present cheese-factory methods is needed by which milk from a large territory can be successfully handled. The great amount of inferior cheese on the market and the lack of uniformity which characterizes the product of the present cheese factory of average size is due primarily to the variable quality of the milk supply from different farms, especially as to the presence of dirt and bacteria, which produce faulty flavors and textures in great variety, and to the variable ripeness or acidity of the milk received from day to day, depending upon the care given to it on the farm, its age, etc. The immediate effect of these conditions is that cheese makers in their effort to produce cheese of uniform quality from milk of variable quality must necessarily use methods which vary from day to day and from factory to factory. Under this system each vat of milk must be watched carefully at every stage of its manufacture, and the 9 [0 OHEDDAB < SBE8I PROM PA8TK1 SIZED MILK. cheese-making process must be hastened, or delayed, or modified ever] day, tccording to the cheese makera 1 judgment. The yield uf cheese also varies from da} to day. depending upon t lit* quality of the milk and the method used id handling it. The ideal conditions for cheese making require an absolutely clean and perfect milk BUpply, and this can not he realized until methods of milk production <>n the farm are vastly improved. In the mean- time a process tor treating milk daily at the factory bo a- to bring it into practically uniform condition for cheese making purposes i- needed. Such a process should include means for Btopping the ripening and the growth of harmful bacteria, etc., in the milk as Boon a- it i» received at the factory, in order that it may be ripened with a clean starter, in a uniform manner, daily. The process should he applicable t<> milk of any degree of ripeness which can properly he accepted a-- lit for cheese making from a sanitary standpoint. When milk is thus brought by a preliminary treatment into uniform condi- tion at the factory, both as to acidity and as to bacterial content, the present variable and irregular methods of making cheese could probably be replaced by a routine process, operated upon a fixed time schedule without variation from day to day. As a result, it is to be expected that the uniformity, quality, and yield of cheese would be much improved as compared with that obtained by the older methods. In many other lines of manufacture in recent year- preliminary proc- esses have been devised for bringing raw materials into uniform condition before they enter the manufacturing process, and improved products, increased economies, and larger output and profit- have resulted. It i- desirable that the same general methods of improve- ment which have been used with success in other lino be applied also to the cheese-making industry. WILTS TO BE CORRECTED IN MILK FOR CHEESE MAKING. The defects most commonly met with in milk, which must be cor- rected by such a preparatory process as that contemplated, are of bacterial origin. A variable content of lactic-acid bacteria causes milk when received at the factory to exhibit different degrees of acidity and also causes the subsequent development of acid in the milk and curd, while in the vat, to go on at varying rates. On unt of the important influence which acidity has upon the rate at which whey is expelled from curd, as pointed otit in a previous bulletin. 1 it may well be said that this is the leading controlling factor in the manufacture of American Cheddar cheese. Therefore it is of prime importance to secure milk of uniform acidity with which to . .... B K... and Laabs, F. \V. Factors controlling the moisture content of cheese Department oX Agriculture, Bureau of Animal Industry, Bulletin 122. Washington, lyiu. Seep 29. NECESSITY FOR PASTEURIZATION. 11 begin choose making, and also to provide for subsequent acid de- velopment at a practically fixed rate every day in order to avoid the present troubles due to irregular acid formation. Those bacteria which produce gas or tainted, unclean flavors are all too common in milk, and are the cause of much trouble in the cheese factory. Bacteria which produce diseases such as tuberculosis, typhoid fever, diphtheria, dysentery, etc., have often been found in milk, although it is difficult to prove that any person ever contracted these diseases from eating cheese. These and other bacterial infec- tions of raw cream and milk for city trade are usually combated by pasteurization; this is true, likewise, in butter making, and with skim milk when used for feeding stock. It seems reasonable, therefore, that any process, such as pasteurization, which will kill the acid, taint, gas, and disease-producing organisms in milk would also im- prove the quality of the cheese produced therefrom. THE NECESSITY FOR THE PASTEURIZATION OF MILK FOR CHEESE MAKING. In view of the possible presence of tubercle bacilli in market cheese, Mohler x in 1908 recommended the " pasteurization of the milk in order to make the cheese perfectly safe." Mohler, Washburn, and Doane 2 prepared and studied cheese from milk to which cultures of bacillus tuberculosis had been added. They inoculated guinea pigs with such cheese at various periods of time after its manufacture and found that — Advancing cases of generalized tuberculosis were developed (in guinea pigs) by means of inoculation of cheese 220 days old, and that slight tubercular lesions were caused by the injection of an emulsion of cheese when 261 days old." They add: If it is possible to Use pasteurized milk in the manufacture of cheese without injuring the product a simple solution of the problem is offered to the cheese manufacturer in the process known as pasteurization. These authors also give a brief resume* of previous work on this subject in Europe and America. It is evident that the bacillus of tuberculosis not only retains its life but also its virulence in cheese for a considerable period of time, and that cheese made from raw, unpasteurized milk should therefore be considered as a possible carrier of tubercle bacilli. There is a strong tendency at the present time to cure American cheese more rapidly than in the past, so that it commonly reaches i Mohler, John R. Conditions and diseases of the cow injuriously affecting the milk. U. S. Treasury Department, Public Health and Marine-Hospital Service, Hygienic Laboratory, Bulletin 41. Washing- ton, 1908. See p. 495. J Mohler, John R., Washburn, Henry J., and Doane, C F. The viability of tubercle bacilli in cheese, Twenty-sixth Annual Report of the Bureau of Animal Industry, U. S. Department of Agriculture (1909), pp. 187-191. Washington, 1911. L2 CHEDDAR 0HXX81 FBOM PABTBUBIZKD MILK. the consumer %i i leas ige ihun four months. It has also been Bhown ' thai practically all d.~> t<« 98 per <<* 1 1 1 of the bacteria presenl in milk arc retained in the oheeae. These fact- Berre to emphasize the desirability of pasteurising milk for cheese making. An ordinance passed by the common council of the city of Chi July 13, 1908, contemplated the pasteurization of milk used for Cheese making, although at that date no practical method- for making American cheese from pasteurized milk had been published. The ordinance \\ ;i- B£ follow ined by the city council of the city of Chicago, * * * ;:<>\ 2 it shall be unlawful to eeU any such cheese in the city of Chicago unleM there !'<• stamped on the package in plainly legible Letters of not Leas than onen inch type: "Made <>!' milk an) bom cows free from tuberculosa as ahown by tuberculin teat," of "made from milk (or cream) pasteurized according i" the rules and regulations ,,i the department of health <>i" the city ot Chicago * * *. " ! Tin- ordinance .-hull be in lull force aii1 HKAI VRY TO DESTROY fABIOUfl BAOTBBIA. The question as to what temperature of pasteurization will kill disease-producing bacteria in milk is of interest to the consumer and all connected with the bushu The thermal death point of various pathogenic organisms i> already Well known. Kosenau states as a result of bifl work and that of otheis that "milk heated to 60° C. (140° F.) and maintained at that temperature tor two minutes will kill the typhoid bacillus." The greal majority of these organisms are killed by the time the temperature teaches 1 or 2 degrees below the point named and few survive to 140° F. The diphtheria bacillus succumbs at comparatively low tempera- tures. Oftentimes it fails to grow after heating to 5.5° C. (131 1 . Some occasionally survive until milk reaches 60° C. (140° F.). The cholera vibrio is similar to the diphtheria bacillus so far as its thermal death point is concerned. The dysentery bacillus is somewhat more ant to heat than the typhoid bacillus. It sometimes withstands heating ai 60° C. (140° F.) for five minutes. All. however, are killed when held at this temperature for ten minutes. 2 In 1904 Russell and Hastings 3 found that the tubercle bacillus is killed by beating at 71° C. (160° F.) for one minute. From the foregoing it is clear that pasteurization at 71° C. (160° F.) lie minute, and in most cases for a shorter period, is effective in »Sant: tamkj B K . raj Eaabs, F. W. Factors controlling the moisture content of cheese r!ment of Agriculture, Bureau of Animal Industry, Bulletin 122. Washington, 1910. Milton J. The thermal death points of pathogenic microorganisms in milk. U. S. Treasury ii.iit, Public Health and Marine-Hospital Service, Hygienic Laboratory, Bulletin 56, pp. 6S3-686. 1 Ku> .ni "fVtl*. 1 <.. Effect of short periods of exposure to heat on tubercle bacilli in milk. Wisconsin Agricultural Experiment Station, Twenty-first Annual Report (1904), pp. 178-192. Mad- Uon, 1904. See p. PREVIOUS ATTEMPTS WITH PASTEURIZED Mil K. 13 destroying pathogenic bacteria in milk and preventing their nit ranee into cheese. Babcock and Russell, 1 from their experiments upon the thermal destruction of galactase, state that "heating the enzym solutions for 10 minutes at 76° C. (169° F.) suffices to destroy the digestive fer- ment galactase, and even at 71° C. (160° F.), for the same exposure, its action was materially reduced." It seems likely, therefore, that an exposure to 160° F. for 1 minute or less in the continuous pas- teurizer would not greatly weaken the action of this enzym in milk for cheese-making purposes. 2 Much less attention has been paid by bacteriologists to the thermal death point of those bacteria in milk which produce gas and tainted flavors in cheese. Moore and Ward 3 have described a gas-producing bacillus isolated from milk and from gassy cheese which "is destroyed in freshly inoculated small tubes of bouillon when exposed to a tem- perature of 60° C. (140° F.) for 10 minutes in a closed water bath." It is to be hoped that in the future investigators will determine also the minimum temperature required to kill various species of milk bacteria with an exposure of 1 minute or less as in the continuous pasteurizer. PREVIOUS ATTEMPTS TO MAKE CHEESE FROM PASTEURIZED MILK. The possibility of making American cheese from pasteurized milk has been studied at several experiment stations and elsewhere. The two difficulties met with are: First, the fact, long known, that heated milk coagulates slowly with rennet, giving a loose, spongy curd which is not suitable for cheese making because it is too fragile to be handled. Second, pasteurization causes curd to expel whey more slowly than otherwise. In order to restore the coagulability with rennet to pasteurized milk, Klein and Kirsten 4 in 1898 added calcium chlorid and a bac- terial starter and were able to obtain fairly good limburger and other soft cheeses. They used for 100 kilograms of skim milk 100 to 125 cubic centimeters of a solution containing in 100 c. c. 40 grams of calcium chlorid, corresponding to 20 grams calcium oxid. 1 Babcock, S. M., Russell, H. L., and Vivian, Alfred. Properties of galactase: A digestive ferment of milk. Wisconsin Agricultural Experiment Station, Fifteenth Annual Report (1898), pp. 77-86. Madison, 1898. See p. 82. 2 Kastle, Joseph H., and Roberts, Norman. The chemistry of milk. U. S. Treasury Department, Public Health and Marine-Hospital Service, Hygienic Laboratory, Bulletin 56, pp. 315-417. Washington, 1909. 3 Moore, V. A., and Ward, A. R. An inquiry concerning the source of gas and taint producing bacteria in cheese curd. New York (Cornell) Agricultural Experiment Station, Bulletin 158. Ithaca, 1899. See p. 236. * Klein and Kirsten, A. Versuche, betrerlend die Wiederherstellung der Verkasumgsfahigkeit erhitzter Milch durch Chlorcalciumzusatz. Milch-Zeitung, vol. 27, no. 50, pp. 785-787, Dec. 10; no. 51, pp. 803-805, Dec. 17. Leipsic, 1898. See also Fleischmann, W. Lehrbuch der Milch wirtschaft. 4th edition. Leipsic, 1908. See pp. 304, 305. 14 CHEDDAB OHEEfi] FBOM PASTBUBIZBD MILK. J 1 1 Denmark i kind of cheese is made from pasteurized skim milk to which about 10 i>»t <«'nt of buttermilk is added bo as to l>riiien and Weak in body and texture. He adds: ( >n the whole the results art- not very satisfactory and ire shall require more light on the subject of making pasteurised milk cheese before we could recommend the : to Canadian cheese makers. In 1010 C. A. Publow 1 mentioned briefly some experiments in making cheese from pasteurized milk, adding to each 100 pounds of milk 2 cubic centimeters of a 25 per cent BohltioD of calcium chlorid and 2 or 3 pounds of bacterial starter. The details of the method and the opinions of cheese judges other than the author respecting the product are not published. At this station in previous years efforts have been made to obtain good American cheese from pas- teurized milk with the aid of calcium chlorid. hut without success. DIFFICULTIES MET IN MAKING CHEESE FROM PASTEURIZED MILK. Pasteurization of milk prevents or greatly delays subsequent coagulation with rennet. The curd from such milk when finally eut into cubes expels moisture with much greater difficulty than a raw-milk curd, probably because of some chemieal change produced in the casein by the heat of pasteurization. Rapid acid formation by bacterial action which occurs in raw milk and raw-milk curds does not occur in the pasteurized material. The presence of a mod- erate amount of Lactic acid in raw-milk curds greatly hastens the separation of whey from the curd, and the lack of acid development m pasieuiTzed-milk curds is another condition favoring the retention of excessive moisture in the curd and che< The addition of calcium chlorid to milk which has been pasteurized 18 known to restore in a measure the coagulability of (he milk with rennet, but we have observed, as Publow 4 points out. that, although coagulation begins in about live minutes, "the curd does not beeome linn enough for cutting in the usual time and should not be cut before it i* linn." Although the addition of calcium chlorid restores .king, oth edition. Madison, Wfc., 1900. See p. 194. • Dean. EL U. BxpflriDttDtl in cheese making. Ontario Agricultural College, Thirty-third Annual ; 130. » Publow, Charles A. Fancy ObMM fan America. Chicago, 1910. See p. 20. 1 Lo U, DIFFICULTIES OVERCOME BY ACIDULATION. 15 the coagulability with rennet, it does not correct the acidity and the other difficulties mentioned above as being caused by pasteurization. The lack of acidity in such curd might be supplied by adding starter to the pasteurized milk and ripening for several hours before starting the cheese making, but the resulting loss of time would prohibit this practice in factories. Where both starter and calcium chlorid are added to milk after pasteurization, as suggested by Publow, and the cheese-making process is begun at once without waiting for ripening, the daily variations in natural acidity of the milk used produce cor- responding variations in the moisture content of the cheese which affect its quality. (See Table 1.) What is needed in place of calcium chlorid for addition to pasteur- ized milk is something which will not only restore the coagulability with rennet, but which will also bring up the acidity without delay to a sufficiently high percentage to induce reasonably rapid and com- plete separation of whey from curd. A uniform acidity is necessary daily so as to avoid daily variations in moisture content of cheese. DIFFICULTIES OVERCOME BY ACIDULATION OF PASTEURIZED MILK. The substance which has been found to meet all of the foregoing requirements and which appears to be unobjectionable from all stand- points is Irydrochloric acid. While it might appear impracticable at first glance to acidulate milk in large quantities daily at a factory, yet upon trial this is found to be entirely practicable; and it has now been done almost daily for nearly three years, without any trouble arising from coagulation of the milk with acid at any time. In Table 1 is shown the moisture content of green cheese obtained on 12 days from pasteurized milk by the use of calcium chlorid in the proportions suggested by Publow (see p. 14) and by the use of hydrochloric acid, using always sufficient acid to raise the acidity of the milk to 0.25 per cent calculated as lactic acid. The milk used in the two vats was taken from the same receiving vat full of milk, after thorough mixing. It was all pasteurized alike and one-half was then treated with calcium chlorid and the other with hydrochloric acid. These were then made up into cheese separately and were sampled for moisture at the time the cheeses were dressed, after pressing one hour. 1 From the table it can be seen that whenever the acidity of the milk used was low (0.16 to 0.18 per cent) the moisture content of the cheese made with calcium chlorid was high (40 to 44.45 per cent), and when the acidity was high (0.21 to 0.23 per cent) the moisture content was low (38 to 40 per cent). But in all cases where hydrochloric acid was added instead of calcium chlorid the moisture content of the card was 37.5 to 40 per cent, whether the natural acidity of the milk was high or low. i The correctness of this method of sampling cheese for the moisture test is demonstrated in the latter p art ofthisbulietin. [6 OHBDDAB III M PASTEURIZED MILK. TABLI 1— Corn, IfRl and fuMj of cheese made with MaMMR • I ..f milk when teur- Moisture content of Critici in. nade. 1 I. vor. ture. or. Text tire. Ml. 17 .17 . 1 7.". . 1 76 .17", . 1 7". .17.'. . 17'. . 1 v.'. . 1 B8 .190 .190 .21 .21 .21 .21 .31 ,lv7 .21o Calcium chlorid ... Hydrochloric add . Calcium chlorid . Hj 'lrrx'hli.r ( allium chlorid . . . Bydrochlorl Calcium chlorid . H> drochloric acid. Calcium chlorid.. . Hydrochloric acid. ( aW lam chlorid . . . Hydrochloric acid. Calcium chlorid.. . Hydrochloric ari-1 t alcium chlorid.. . Hydrochloric acid. Calcium chlorid.. . Hydrochloric arid. Calcium chlorid. . . Hydrochloric acid. < allium chlorid .. . Hvdrochloric acid. do do do Calcium chlorid.. . Hydrochloric acid. Per crnt. 87.70 13 38 38.80 41 BO ■a: 7ii 44.27 39.20 44 27 39.62 44.46 39.02 42.90 39.90 41.50 39. 95 39. 20 39.62 38.60 40.60 39. 95 39. 05 38 41* 40 41 M 411 2| 17 41 411 41* 40 8 1 g' 41 39 411 41 41 26 24 27 25 26* 25 26 27* 26 26* 26* 17 26J 27 | Flat, punpent Clean Curdv.loo.se, weak. Trifle , juiv a Plat, Lackinj ('Iran and 0. K . . acid Trifle add... Trifle weak. md sticky. kicky. Trifle weak. Do. \ >rv loo-e. weak. Trifle m Stick] . loo^e, short. Kxu n Do 1 Low, LackJn| Trifle hat] Sour-milk flavor. . Trifle sharp (loan and O.K... o. K 1 Hitter, larks acid.. O.K Coarse, loose. 1 I'M ... Aup. i: Aup. 11 P.. Aup. : fcug, Li \ hitter Acid aftcrta do * Vinegar flavor Clean and O. K . .. Trifle bitter Weak, mechanical holes. Mechanical holes. Weak . Loose, sticky. 'ides.' Trifle 1 Short, stickv. Trifle short.' 38.67 •i 42.00 39. 45 41.23 25. 73 Prom the above table it is evident that when milk is acidulated with hydrochloric acid after pasteurization, as in the new method, the moisture content of the green cheese is not affected by the ripeness of the milk before pasteurization and is quite constant between 37.5 and 40 per cent. This advantage does not attend the use of calcium chlorid. The daily variations of moisture content shown in column 4. which are between 37.5 and 40 per cent, are doubtless due to causes other than acidity, and did not Qoticeably affect the quality of the ch( The BOOree and criticisms show that the cheese made with calcium chl<»rid was neither ;:s uniform Dor as good in quality as that made with hydrochloric acid. The addition of hydrochloric or lactic acid to cream to raise Its acidity without delay, preparatory to churning, was attempted by Babcock in L888. 1 The addition of a commercial acid to raw milk 1<> raise its acidity without waiting for bacterial action was BUggested to the writer in 1905 by Dr. S. M. Babcock. chief chemist of the Wisconsin Experiment Station, and during the years L905 6 the effort ^n- made, following the suggestion of Dr. Babcock. to avoid the necessity for ripening milk for cheese making at the factory and M ChurninK U mbl Igrioultora] Kxperiment station. Fifth Annual Report, - Sec p. IIS. notes , m this subject in s 3m e volume, pp. 125, 4ft4, 701, 750. DIFFICULTIES OVERCOME BI iCIDULATION. 17 to substitute for such ripening the addition of a commercial acid to the milk as soon as it was received, [mmediately after acidulating the milk it was heated to 86° and rennet was added and the process completed in the usual manner. Those experiments slowed conclu- sively that a commercial acid such as bydro< hloric a; id can he added to milk without in any way damaging the quality of t be < beese obtained. However, the quality of choose obtained from overripe or tainted milk was not improved by the use of the acid, and it was concluded that acid ulat ion alone does not offer sufficient advantages to warrant its recommendation to cheese makers. The addition of acids to pasteurized milk for choose making was begun by the writer in 1907. Pasteurization and acidulation of milk appear to be complementary processes, each supplying what the other lacks and together forming the basis of an improved method of cheese making. Since the use of calcium chlorid in pasteurizod-milk cheese will not be referred to again in this paper, two other points will be mentioned hero in which the use of hydrochloric acid is more advantageous. Those are: First, that the hydrochloric acid curds always begin to thicken 6^ to 7 minutes after rennet is added, while with calcium chlorid the first visible coagulation occurs earlier if the milk used is very ripe and later if the milk is sweet, thus varying from day to day, as shown in Table 2. Second, the percentage of fat lost in the whey is on the average about 0.14 per cent greater in the method using cal- cium chlorid than when hydrochloric acid is used, as also shown in Table 2. This is probably because calcium chlorid curds are always more mushy and easier to break up in stirring than curds made with hydrochloric acid. The latter are really superior in this respect to curds obtained by the regular factory methods. Table 2. — Comparison of calcium chlorid with hydrochloric acid as to their effects on chee&e made with pasteurized milk. Date. Time required for visible coagula- tion after adding rennet. Per cent of fat in whey at time of drawing whey and ma 1 1 i n g curd. Acidity of milk used. Calcium chlorid. Hydro- chloric acid. Calcium chlorid. Hydro- chloric acid. 1911. July 28 Aug. 11 16 17 18 22 23 24 25 28 Average.. Minutes. 14 15 6 4 14 141 18 18 16 .6* Minutes. 7 7 7 7 7 7 7 7 7 7 Per cent. 0.23 .35 .16 .21 .32 .32 .39 .42 .38 .17 Per cent. 0.13 .14 .12 .14 .19 .18 .20 .20 .16 .13 Per cent. 0.17 .185 .21 .21 .165 .165 .175 .175 .175 .22 .295 .159 79994°— Bull. 165—13- Is OHEDDAB 0HBE8I FBOM PA8TEX7BIZED MILK. THE PASTEURIZATION PROCESS. PASTEURIZATION I \ a DISCONTINUOUS OB iu:i.l>" PASTEURIZES. In M;i\ . L907, one day's milk supply was divided in two portions, one of which was made up by the regular method and the other was pasteurized for I"*- minutes at 160° F. and acidulated with hydro- chloric acid. 'Idic pasteurized vat gave the best-flavored cheese after curing, though it was inferior in texture to the other, (hi March 12 and 27, 1908, milk pasteurized at 140° for 20 minutes and then acidu- lated gave Buch good cheese that a systematic Btudy of the combined process of pasteurization and acidulation was begun in Jury, L908. Cheese was made from milk pasteurized at l lo F. for 20 minutes, either in a Potts pasteurizer <>r in the cheese vat, by ronning first Bteam and then cold water into the jacket. At the >aine time part of t he milk Bupply after mixing and dividing was used for making cheese by the regular methods. The scores given to the two Lots of cheese thus obtained are shown below : Taule $.— Comparison of flavor :.:':. 81 10.25 36.5 26.5 40.58 L'T.on 3S.30 26.66 The, scoring was done by J. W. Moore and F. W. Laabs. In BVeiy case hut one the pasteurized cheese had better flavor and there was little difference in texture between the two lots. CONTINUOUS \\l> HELD PASTEURIZATION COMPARED. On account of the Large volume of milk which must be handled daily in a cheese factory, and the greater expense involved in providing arrangements of sufficient capacity for beating and cooling 5,000 to ! pounds of milk at one time BS compared with the small cost of a continuous pasteurizer, most of (he later work was done with continuous pasteurizers. These can he used for handling any required volume of milk, a larger quantity simply necessitating a COMPARISON OF CONTINUOUS AND HELD PASTEURIZATION. 19 longei time for running. At the present time they are believed preferable for cheese-factory use over any form of intermittenl pas- teurizer vet devised. Good results had been obtained by pasteuri- zation at 140° for 20 minutes, but since continuous pasteurization Beemed the more practical factory method, it was determined to use both methods in comparison on the same milk for several days. On eight days, between July 16 and 24, 1908, half of the milk was pas- teurized at 140° for 20 minutes and the other half at either 150°, 160°, or 170° in the continuous machine. The effectiveness of the two methods of pasteurization was judged from the increase in acidity observed in the whey within the time from cutting curd to drawing whey specified in each case. Table 4. — Increase of acidity after pasteurization by continuous and by held processes. Date. Milk held at 140° for 20 minutes. Miik pasteurized at 150°. Instan- taneous. Milk pasteurized at 160°. Instan- taneous. Milk pasteurized at 170°. Instan- taneous. In- crease. Time. In- crease. Time. In- crease. Time. In- crease. Time. 1908. July 16 17 18 20 21 22 23 24 Per ct. 0.11 .068 .055 .01 .02 .03 .078 .018 H. m. 2 57 2 17 2 17 2 31 2 19 2 21 2 10 2 30 Per ct. H. m. Per ct. 0. 055 .03 .03 H. m. 3 2 59 2 46 Per ct. H. m. 0.01 .01 .035 .053 3 30 3 30 3 20 3 8 0.01 2 40 From the above it can be seen that where milk is highly inoculated when raw, as on July 16, 17, 18, and 23, the acidity of the whey rose 0.05, 0.06, 0.07, and 0.11 per cent in about 2\ hours after pasteur- izing at 140° for 20 minutes, while it rose only about half as high in 3 hours after pasteurizing at 160° or 170° in the continuous machine. A further substantial difference between curds from milk pasteur- ized on the one hand at 140° for 20 minutes and on the other at 160° in the continuous machine is that the former curds often become mel- low and greased on the surface and leak white whey after milling, in this respect resembling some raw-milk curds. It was supposed at first, from analogy to ordinary factory methods, that the curd which became mellow and somewhat greased on the surface and which leaked more or less white whey was more likely to turn out well than the other, which was supposed to be lacking in acid or acid-forming bacteria. The observation was made that a curd from milk pasteur- ized at 170° and afterwards treated with 5 per cent starter did not become mellow in the least, while curds from the same day's milk pasteurized at 140° for 20 minutes and then treated with three- (Ill DDAR (ill I SE FROM PAS! EUBIZED MILK. fourths per cent starter, became very mellow and abundantly greased before milling. It was j i m Ilt*-« I unnecessary, thereafter, bo wait for mellowness or any other evidence of bacterial action or acid develop- ment in a pasteurized-milk curd. If a sufficient proportion <»f Btarter has '"•-•ii ads to be regarded as objectionable and as evidence of lack <>f uniformity between different days' make, and since this n iver occurs with milk pasteurized at L60 c in the continuous machine the hit ter appeals preferahle. The cause for the greater increase of acidity in whey after cutting curd from milk pasteurized at 140 for 20 minutes, a- shown al i- in- doubt the fact that the milk thus pasteurized contained more living, active bacteria than that pasteurized in the continuous machine. Sample- were taken for bacteriological count in every case immediately after pasteurizing, and then three-fourths per- cent of starter was added to each \at, followed immediately by rennet as soon as the vat could he heated. Bacterial count- were made on these samples by Mr. L. D. Bushnell, bacteriologist, as follow - : Table. Number of bacteria per cubic centimeter in raw and pasteurized milk. Date. Raw milk. Pasteurized milk. At 14')° for 20 minutes. In continuous machine. 1908. Julv 17 18 30 21 22 23 21 Number per c. c. 102, (XX), 000 72. (XX). (MX) !HUHX),000 00,000 173. (XX). (XX) 3G0,(x 66, (XX), 000 Number per c.c. 2,306,000 -O.000 33,000 .000 16,820,000 62,000 Number per cc. -.000 (.000 200,000 9,200 38,000 1,300.000 1,100,000 °F. 160 100 170 170 170 170 150 SELECTION OF BEST TEMPERATURE FOR PASTEURIZATION IX THE (ONI [NUOUfi MACHINE. The temperature -elected should be high enough to insure that the ri| ening of the milk shall he uniformly checked daily, regardless of the bacteria] content of the milk used, and it should not be so high as to injure the quality of the cheese. Testa were made as follow-: Qd several days the milk supply after mixing was divided into four lots, one of which w a- made up by regular methods, the other- were pasteurized at 140°, 150°, and 1G0° and made up in separate vats. The cheese after curing was examined by several r.i.sr i i.\iri:i;\ hue for r.\srKii{iz.\TKix. 21 export cheese judges, Including Messrs. U. S. Baer, Etoberl McAdam, H. J. Noyes, K. W. Laabs, and Gottlieb Marty, whose score- are given in Table 6: Table G. — Quality of cheesi made from raw milk and from milk pasteurized at different temperatures in the continuouS'disk machine. Date. Pasteurized at— 140° F. 150° F. 100° F. Flavor. Tex- ture. Flavor. Tex- ture. Flavor. Tex- ture. Flavor. Tex- ture. 1908. July 14 15 16 17 20 21 22 15 IG 17 20 21 22 23 24 40.0 40.5 38.0 38.0 40.0 41.0 37.0 28.5 28.5 28.0 28.5 28.5 28.5 28.0 41.5 41.0 40.0 41.0 41.0 41.0 38.0 28.5 29.0 29.0 29.0 28.5 28.5 28.0 43.0 41.0 41.0 42.0 42.0 41.5 39.0 41.0 44.0 42.0 40.0 44.0 41.5 38.0 44.5 43.0 40.5 44.0 41.0 40.0 40.0 44.0 37.0 40.0 35.0 43.0 40.0 43.5 36.0 28.5 29.0 29.0 29.0 29.0 29.0 27.5 27.5 28.0 28.0 27.0 28.0 28.5 23.0 29.5 29.0 28.5 29.0 28.0 28.0 27.0 29.0 29.5 25.0 25.5 27.0 28.0 28.5 26.0 40.6 36.0 36.0 38.0 39.0 35.0 38.0 40.0 40.0 38.0 38.0 36.0 37.0 40.0 35.0 37.0 42.0 33. 36.0 37.0 39.0 36.0 42.0 37.0 44.0 36.0 43.0 32.0 28.5 27.0 28.0 28.5 29.0 28.0 27.0 26.0 26.0 26.0 24.0 27.0 26.0 26. 26. 5 26. 27.0 28.0 28.0 25.0 26.0 28.0 28.0 27.0 26.0 27.0 28.0 28.0 In nearly every case the 160° pasteurized-milk cheeses were cleaner in flavor and scored higher than the check, and in every case they scored higher than the cheeses pasteurized at 140° and 150°. The different judges scored the cheese at different ages, which will account for the wide variation of some scores. Bacterial counts made by Mr. W. H. Wright 1 show that pasteurization at 160° is more effective than at lower temperatures. This is well illustrated in Table 7. Unpublished work by W. H. Wright, instructor in agricultural bacteriology, University of Wisconsin. CHEDDAR CHEESE FROM PASTE1 SIZED MILK. ial content of milk) Itemperatt ont'uiuous- machine. MllllC. Milk i-u-w-urized at— 1+J° r. 150° F. Jul. B M 6,080,000 1,5-*. 600,000 50,000 11,60 That the use of 160° for pasteurization is high enough to kill most of the bai teria in milk, so as to meet requirementfl Mich as those of (he Chicago ordinance previously referred to on page 12, is shown in Table S by the following bacterial counts made by Mr. Alfred Larson in 1909: Tjlblk 8.— Bacterial content of milk before and after pasteurization in the continuous- disk machine at 160* P Date. Bacteria per cubic centimeter. Decrease. Raw milk. Pasteurized milk. 1909. Per cent. Aup. 17 161,600,000 223,350 99.8 18 43,300,000 1.275,000 97.0 19 -1,000 211,600 99.6 20 •<>,000 21 20,^ 99.8 22 15,543 97.0 24 SO, 600 99.0 26 44,075,000 99.8 27 70,000,000 99.9 28 05,000 166,460 99.8 31 148,200,000 99.9 Sept. 1 - ..IKK) 99.9 2 99.9 14 50,000 99.9 10 ' 1,606 341.606 99.6 17 38, 91 - 99.6 18 124,766,660 19 99.5 •Jl 185,00 477,660 99. 8 22 100,666 99.7 23 85,000 28 29 13,680,606 51,000 30 14,580 9S.5 1910. July 11 6,500.000 93.6 12 1,660,000 25,000 u 14 4,70 99.3 15 10, (H 1 99.7 20 5,350,000 99.6 Sept. 19 2,525,000 30,000 98.8 OBJECTIONS TO HIGH TEMPERATURES FOB PASTEURIZATION. 23 Similar determinations were made by Miss A. C. Evans upon milk pasteurized in the continuous "Hash" machine in 1910. They are shown in Tabic 4 9: Table 9. — Bacterial content of milk before and after pasteurization in the continuous ' 'flash' ' machine at 160° F. Number of bacteria per cubic centimeter. Date. Killed by pasteuriza- Raw milk. Pasteurized milk. tion. 1910. Per cent. Aug. 3 7,950,000 4,700 99.95 4 4, 250, 000 15,300 99.65 5 9,750,000 142,000 98.45 9 1,500,000 4,850 99.68 11 6,450,000 11,250 99.83 15 2,850,000 43,600 98.47 16 1,017,500 12, 725 98.75 17 38,000,000 700 99.99 18 4,500,000 6,000 99.87 19 3,750,000 5,500 99.86 24 18,150,000 13,800 99.93 25 14,000,000 6,500 99.96 30 47,300,000 16,200 99.97 Sept. 1 2, 150, 000 12,000 99.44 7 5,650,000 27,000 99.53 8 8,800,000 63,000 99.29 9 2,800,000 5,500 99.80 12 10,200,000 21,200 99.73 13 2,120,000 18, 500 99.13 16 18,000,000 5,700 99.97 19 2,525,000 4,300 99.83 21 1,700,000 11,000 99.35 23 9,000,000 30,000 99.67 26 11,200,000 28,000 99.75 OBJECTIONS TO HIGHER TEMPERATURES THAN PASTEURIZATION. 160°-165° F. FOR Cheese made by the new process from milk pasteurized at 160° has always a clean, mild flavor which suits practically all markets, and will please any consumer who likes a mild-flavored cheese. Those who are accustomed to and prefer very old high-flavored cheese would not be suited, but estimates by leading cheese dealers indicate that the proportion of consumers preferring the high-flavored cheese is very small. Most of the cheese sold to-day is only a few weeks old, because the dealers generally avoid long storage, preferring quick sales and immediate profits. Tins makes it practically impossible for most consumers to develop a taste for any but the new mild cheese sold in most markets. The steady sales of pasteurized-milk cheese during the past two years indicate that the flavor of the 160° pasteurized product is satisfactory for filling regular orders. Indeed, it is an open question whether most of the "high snappy'' flavor often observed in old cheese is not due to the long-continued, slow development of those same taints and off flavors from unclean milk which we recognize as objectionable when they develop rapidly. 24 CHEDDAR CHEESE I BOM PAS! EUBIZED MII.K. The use of 1 1 i lt 1 1 < * i temperatures than 160° For pasteurization was tried on Beveral days, with the result that the flavor production in the cheei practically prevented and the texture was inferior. The scores given to these cheeses are tabulated below: 'Jaii.i in Quality from milk pasteurized ni different temperaturet in Ou. continuous-disk nun ■ •1 ;it Paste rized at lui | 17(1° F. WW i made Flavor. Ocl 12 4«i - 27 18 13 40 28 35 IS n 40 Zl IS The scoring was done by Mr. F. W. Laabs. The w>° cheeses have < heddar flavor, but taste like first-class cottage cheese. They jo crumbly and short that it la impossible to draw a solid plug. Tlie\ keep well, and it is possible thai a good trade ought be built by the sale of this product under some such name as " pressed cottage cheese." En all cases the i se of 100° for pasteurizing milk gave better se than higher temperatures. Three reasons have been suggested why the milk pasteurized at lso° gives flavorless cheese; First. If bacteria are the essentia] cause of flavor production, it would appear likely that the necessary kind- of milk bacteria are oyed by the high temperature of pasteurization. ond. If milk enzyms such as galactose are the essential cause of flavor production, these enzyms are perhaps destroyed by tie of 180°. Third. It may be that the casein or other native milk constituent which in normal cheese undergo - cl forming the flavor-giving Bubstances present in ripened cheese, is changed chemically either in : osition or as to constitution by the heating to 1J hat upon cleavage by bact< ria, enzj s, acids, or other agencies it yields differ- ent cleavage product-. Lacking the flavor, etc., which characterize rial chees In attempting to test the first of these possible explanations a variety of substances have been added as Btarters to milk after teurizing at 180 or other high temperatures in order if possible to Bupply the bacteria or enzym needed for normal curing and flavor production. Among the special Btarters bo used were pure cultures Of various bacteria: raw milk up l() - (! P ,T (( ' ,:t °f tr,< V:lt contents; cultures of bacteria isolated from jnilk and che< >< capable of develop- EFFECT OF PASTEURIZATION ON ( IIKKSE CURD. 25 ing 1 .(> percent or more lactic acid in milk (described by Hastings 1 ); cheese of various ages rubbed to creamy consistency with milk and added in different proportions through a hair sieve to the pasteurized milk in the vat; eultures made by adding cheese in this manner to milk and incubating overnight before adding to the cheese vat. All of ties- materials were added to milk which had been pasteurized at higli temperatures up to 180°, and cheese was made therefrom; but in no case was it possible to get a normal flavor development in the resulting cheese. The lack of flavor production under these circumstances, wdiere many kinds of bacteria and starters were added to the pasteurized milk, seems to indicate that the casein, etc., in milk thus treated is incapable of cleavage into the flavor-giving substances; in other words, that the casein, etc., is changed chemically by the heat of pas- teurization. There is additional evidence that such a change occurs. EFFECT OF PASTEURIZATION OX THE PROPERTIES OF CHEESE CURD. A series of cheese curds made from milk pasteurized at 160°, 170°, 180°, or higher temperatures show a regular gradation of certain char- acteristics. The higher the temperature of pasteurization the more tenaciously the curd retains moisture and the more difficult it is to expel the whey by ordinary means. This is shown in the following experiment: The milk in the receiving vat each morning w r as thor- oughly mixed and then divided into three portions which were run through the pasteurizer at different temperatures and made up into cheese in different vats. Three-fourths per cent of starter was added to each vat and the milk and curds w r ere handled in all respects as nearly alike as possible, the only difference being in the temperature of pasteurization. The curds in separate hoops were pressed in the same press, and the next morning moisture tests were made on each. This entire work was repeated on several days. The results are shown in Table 11. Table 11. — Moisture content of green cheese made from milk pasteurized at different tem- peratures in the continuous-disk pasteurizer . Date. Milk pasteurized at— 160° F. 170° F. 180° F. 1909. Oct. 12 13 14 Per cent. 38.4 37.0 39.0 Per cent. 42.2 39.9 40.7 Per cent. 46.6 43.5 45.5 i Hastings, E. G., Hammer, B. W., and Hoffman, C. Studies on the bacterial and leucocyte content ot milk. Wisconsin Agricultural Experiment Station, Research Bulletin 6. Madison, June, 1909. CHEDDAR CHEESE FROM PASTEURIZED MILK. Bach per cent given is the average of two closely agreeing dupli- cates. It i- seen that in every case the higher temperatures of pas- teurization cause higher moisture content in tJir green cheese. These curds were all cut with a three-eighths-inch knife and heated to mi in the \\ hey. Even when a 180 curd w;i> cut wit ] i one-fourth inch curd knives and a KK» curd with three-eighths inch knives, the moisture content in the former remained higher, a-- is shown in the follow ing experiment : Taui k i_ content qfcurdi madefrom milk pasteurized at different tunpcratures at the amt&nuout-disi pa U win knives of different aizts. Milk pasteurized at 160° F. Milk pasteurized at Time ftftef cutting curd. Cut into f-inch Cut into |i'ich Cat into J-inch //. m. 1 () Per cent. 60. l 17 2 4.}. a 42.2 41.4 Per cent. 70. 63.9 52.4 47.2 45.9 45.1 Per cent. 66.5 61.0 50.6 #6.0 44.6 43.9 2 o Drew whey... 2 30 3 30 Milled curd... 4 30 Salted cud... 4 50 Hooped curd. Each per rent in the table is the average of two closely agreeing moisture determinations. It is unquestionably true that pasteurized-milk curds retain mois- ture more tenaciously than raw-milk curds, and this effect is more marked the higher the temperature used in the pasteurization. It therefore follows that the higher the temperature used in the pasteur- izer the greater will be the weight of cheese obtained from pasteurized milk. The yield per hundred pounds of milk weighed before pasteur- ization in each vat on three days is given in Table 13. Table 13. Yield of cheese per hundred pounds of miU: pasteurized at different tempera- tures. Date made. Temperature of pasteurizat ion. 160° F. 170° F. 180° F. 1909. Oct 12 a 14 Poumh. 12 X 12. 10 11.93 Pounds. 1.5.42 1.- '.'7 Pounds. 15. 42 14.53 14.44 It will be shown later that the yield of cheese obtained by pastcur- izing at lfii i i> slightly greater than that obtained from raw milk, so that in this ropect the effect of pasteurization is distinctly noticeable even when the lower teniperat ure is used in the pasteurizer. Again, EFFECT OF PASTEURIZATION ON CHEESE CURD. 27 among the peculiarities of pasteurized-milk curds is their decreased power to coalesce or mat when on the rack or in the press. This effect is not noticeable with milk pasteurized at 160° to 165°, but is perceptible at 170° and is very marked when the milk was pasteurized at 180° or higher. The 180° curd cubes when piled on the rack pack together like raisins or figs in a box but do not coalesce or unite, and by rubbing the linger over the mass at any time the pieces can be pulled apart. The same effect is noticed when the curd is pressed in the hoop. The pieces pack together tightly but do not unite; and at any time during the curing a plug drawn with a trier will either come out in fragments or will break into pieces instantly wben han- dled. Instead of milling such a curd, it is merely stirred or shaken apart with the hands. These two peculiarities of pasteurized-milk curds, which can not be remedied or avoided by any other means than reducing the tem- perature of the pasteurization, considered together with the impos- sibility of developing Cheddar flavor after pasteurization at high temperatures, appear to indicate that the pasteurization produces some deep-seated change in the chemical constitution of casein. Another peculiarity of pasteurized milk, that of coagulating with rennet only with great difficulty, need only be mentioned in this connection, because in the process of cheese making here described the addition of hydrochloric acid to the pasteurized milk entirely restores the coagulability w T ith rennet, producing a curd in many respects superior to and easier to handle than the curd commonly obtained in the regular way from raw milk. From what has been said it will be seen that the use of 160° to 165° for pasteurization offers many practical advantages. It is sufficiently high to check effectually the further ripening of the milk during the next few hours, while the use of 150° is not high enough for this pur- pose. Furthermore, 160° gives cheese of cleaner flavor than 140° or 150° (no doubt by more effectual destruction of taint-producing bacteria) or than raw milk, as shown in Table 6. It may be mentioned also that over 99 per cent of the total bacterial content of the milk is destroyed by use of 160°, as shown in Tables 8 and 9. The 160° is preferred to 170° or 180° because the cheese obtained by the use of 160° is more nearly like the best American cheese in moisture content (see Table 11) and in texture and flavor. (See Table 10.) So far as it is possible to say at the present time, the use of 160° is sufficient to kill most probably 99 per cent of the gas and taint- forming bacteria in milk. It can not be claimed that they are all killed, because it is true that when very unclean milk is handled by this process the cheese sometimes shows slight traces of unclean flavors, though not enough to affect the market value. While gas and pin holes have often been seen during the seasons of 1909, 1910, OHEDDAB CHEESE FROM PASTEURIZED MILK. and 1911 in cheese n ade l»\ regular methods at this factory, no whatever was Been in any curd or cheese n ade during 1909 or 1**1 1 . and the obtained, nine days in succession, in 1910 was demons! rated to be due to the use by mistake of st arter which added to the i ilk after pasteurization. The fault arose at thai fro i the ii efficient n i ai - then at J. a: d for pre] aring and heat- ing milk for propa at ion of i he si arter. An in prov< d stea i sterilizer was at once Bet up for this purpose, which prevented all further diffi- culty of this soil during the past two years. The temperature finally selected as most completely securing the advantages and avoiding the disadvai of pasteurization for cheese making is 160 to 165 F. In practice the pasteurizer is running at 163 and held th< re as closely as possible. THE DIFFERENT TYPES Oi CONTINUOUS PASTEURIZERS DSED. Two different pasteurizers were used in this work with entire Buccess, being apparently equally effective in producing the des results at 160 to 165 . Tj ese were a disk machine of 2,000 pounds per J cur capacity and a "flash" n achine of 1,200 pounds capacity per ho p. See Pis. II and 111.) The choice between these two types of pasteurizing machines for use in this process appears to depend upon their relative cost and ease of operation and cleaning, rather than upon any diff< rence in eff< cl iven< bs. They w< re us< d alternately on successive day- for several week-, and on three day-. September 1 . 1l\ and l ( .>. 1910, the milk was divided, one-half being run through each. The cheese was first class in each case and Bhowed no differ- ence s that ( ould be traa d to the use oi different machini 9. THE ACIDULATION PROCESS. THE STANDARD ACDDITl OF MILE FOB CHEESE MAKING. Milk as it Bows from the pasteurizer varies daily in acidity and is Lacking in bacteria of the lactic-acid type, needed to aid in cl curing. By the addition of sufficient hydrochloric acid to raise the acidity of the milk to 0.25 per C4 nt (as lactic acid' after pasteurizing, and of three-fourths per cent of a first-class -tarter, the pasteurized milk i- brought daily into Standard condition both as to acidity and bacterial content for cher-e-n akiiiLT purposes. The reasons for adding acid and -tarter a- specific d will row be given in detail. The Btandard acidity is 0.25 per cent, and the acidity of pasteur- ized milk i- raised to this figure rather than to 0.20 or 0.30 per cent for the following tea-' PilBt. In regular cheese making the acidity of whey when drawn b on the average, about 0.17 per cent, corresponding to an acidity STANDARD ACIDITY OF MILK. 29 of milk of about 0.2."> per cent. Anyone can test the correctness of this statement by transferring a pint of milk from a cheese vat, just before adding rennet . to a small tin pail, keeping the milk sample at the same temperature as the vat and titrating the milk in the pail as well as whey from the vat at intervals. When the whey reaches 0.17 pei cent the milk reaches nearly 0.25 per cent. The control of acidity at the instant the whey is drawn is commonly regarded as most important in regular cheese making. With milk pasteurized at 160° there is little or no increase of acidity (usually about 0.01 per cent) in whey, before the whey is drawn. The acidity of milk is adjusted to 0.25 per cent in this process after pasteurizing in order to parallel ordinary working conditions at the time of drawing the whey. Second. Mixed milk in the factory cheese vat is commonly at 0.16 to 0.18 per cent acidity when received, although often at 0.19 to 0.21 per cent. It should never be over 0.23 per cent acidity. It is found that an addition of hydrochloric acid equal to at least 0.02 per cent of lactic acid is required to restore the coagulability with rennet to such milk after pasteurization, but the daily addition of only 0.02 per cent of acid would leave the milk of varying acidity, which is objectionable. If 0.20 per cent were adopted as the standard acidity, after adding 0.02 per cent in the form of hydrochloric acid, this rule would exclude from use all milk having a higher acidity than 0.18 per cent when received, which it is not desirable to do. Only rarely is a vat full of milk at 0.23 per cent acidity received at any factory, but even such milk can be handled in the routine manner at the stand- ard acidity of 0.25 per cent by adding the required 0.02 per cent of hydrochloric acid after pasteurization. It might be stated as a matter of record, not as a precedent for factory practice, that vats of milk of 0.24 to 0.28 per cent acidity when received have been successfully made up into good cheese with- out varying the process in any particular, excepting that only enough acid is added after pasteurization to raise the acidity 0.01 per cent, which is sufficient to restore the rennet coagulation to such ripe milk. The only apparent limit of acidity for milk to be handled by this process is that the milk should not, of course, be sour enough to curdle in the pasteurizer, and this limit is reached at or about 0.30 per cent. However, it should be recognized by everyone that milk that has reached 0.30 per cent or even 0.25 per cent acidity before it gets to the cheese factory must have received very poor care and attention on the farm and must be entirely unfit for cheese making from a sani- tary point of view. 30 CHEDDAB CHEESE PROM PASTEURIZED MILK. COMPARISON <>i DIFFERENT KINDfl "I iCWB FOB USE EN CHEESE M \ 1 1 " • ■ ( )f the more common acids sulphuric, hydrochloric, and phos- phoric the first is the least convenient to handle, especially in a cheese factory . be< ause of the great an ount of heat liberated when it is diluted, and the impossibility of diluting it in the carboy in which ■■ i ved. Hydrochloric acid is much better in this respect as n med to have a Blight peculiarity of flavor, as a rule, after curing. Most of the cheeses made from pasteurized milk have bo far been made with hydrochloric acid, and the use of this acid is described and rec o:n- mended in the present bulletin. The selection of hydrochloric a< id was made because it is cheap and more easily obtained than any other chemically pure acid, and being a natural i onstituent of gastric juice in the human stomach, no objr< tion could be raised on sanitary or other grounds against its use m this p TIIK PROPORTION OF HYDROCHLORIC \( ll> REQUIRED DAILY. it is necessary to determine first what the acidity of each vat of the mixed milk is. in order after pasteurizing to add the requisite quantity of hydrochloric acid to bring the acidity up to 0.25 per cent. Where only one vat of milk i^ to be pasteurized and only one workman TESTING MILK FOR ACIDITY. 31 is employed it is probably better to weigh in all the milk then stir the vat well and take out a half cupful of milk for the acid test. Where two men are employed and it is desired to start the pasteurizer running as early as possible (before the receiving vat is full), the intake man should take from each weigh can of milk a sampling tube full, mixing these samples in a pint jar. The acidity of this mixed sample will then be the same as the average acidity of all the milk run into the vat. As soon as one vat full of milk (say 5,000 pounds) has been run from the weigh can into the receiving vat, the pint jar containing the sample for the acid test is handed from the intake to the man running the pasteurizer, together with the total weight of milk run into that vat. The pasteurizer was started when perhaps only half of this milk had been received, but the receiving vat is still about half full, and after making the acid test on the sample the operator can tell exactly how much more hydrochloric acid must be added, while pasteurizing the remaining milk in order to bring the acidity of the whole vat up to the right point, or 0.25 per cent. TESTING MILK FOR ACIDITY. In determining the acidity of milk, measure a 17.6 cubic centimeter pipette full of milk sample into a white china cup, which should be shallow and wide rather than narrow and deep. Add two drops of phenolphthalein indicator and while shaking or stirring the milk in the cup run in tenth-normal alkali (Manns's solution) from a burette, rapidly at first, and later by single drops, until the faint pink color pro- duced by the last drop does not disappear on thorough, mixing. The volume of tenth-normal alkali used is read from the burette, and this volume divided by 20, which can be done mentally, gives the exact acidity of the milk in per cent of lactic acid by weight. For example, if the volume of alkali solution used was 3.2 cubic centimeters the acidity is 3.2 divided by 20, which equals 0.16 per cent. Subtracting the acidity of the raw milk from 0.25 per cent shows how much the acidity of the milk is to be raised with hydrochloric acid after pas- teurizing. For example subtracting 0.16 per cent from 0.25 per cent leaves 0.09 per cent, which shows that the acidity is to be increased 0.09 per cent with hydrochloric acid. The outfit needed for testing milk is shown in Plate I. It consists of: 1. A burette with rubber tip and pinchcock; capacity 25 c. c, with Yo c. c. graduations. 2. A 17.6 c. c. pipette as used for the Babcock test. 3. A white china teacup, which is best if shallow and wide and with flat bottom. 4. A support for the burette, which may be an iron stand and clamp, or a wooden strip with a hole in it, fastened to a window casing, as shown at the left in Plate I. CHEDDAB CHB] 4 PASTEUBIZBD MII.K. \ rubber-stoppered bottle of Manns's - luti d (tenth-normal alkali which may be purchased at SI per gallon of dealers in dairy supplies, or may be made by diluting the normal alkali b Lution, which mu>t be purchased as it is required in this pr i ess as described on i' ii \ 2-ounce or t-ounce bottle of phen lphthalein indicat r b -lu- ti .n. 7. The additional outfit required for use in this pr cesa of clu making is ale i shown in the figure. It coi sists of 1 gallon of normal alkali (ten times as Btrong as Manns's neutralizer . a 50 cubic centi- meter measuring flask, a 500 cubic centimeter measuring cylinder, and a 2 cubic centimeter pipette, which should be accurately made. A gallon of n rmal caustic alkali contains about 5 ounce- of ca s mIji. Worth about 15 cent-, and Bh »ul\i lei with a rubber -t >pper, and to fill this smaller b ttle occasi 'Dally fr m the Larger b ttle. which is then put away, tightly Bt >ppered, in a Bafe place. The small 1> ttle is kept near the burette and used daily in filli ig it. and the large b ttle is thus pr tected from unnecessary exp sure. 1 ss < f strength, and fr >m r \ Bpilling. The use I f tw i h .ttles in this manner has pr vcn in si satisfactory in this lal>< ratory and dairy school during the past four year-. It i- recommended 1 as a means of avoiding less of gth thr, ugh exp' -ere to the air. which has bereft f* re been the greatest difficulty to overct me in the i Be of Manns's test in the cl factory. DILUTING NORMAL ALKALI TO TENTH-NORMAL. One may prepare tenth-normal alkali by diluting the normal alkali 11 avs: Tour into a 500 cubic centimeter graduated cylinder exactly "><> cubic centimeter- of the normal s lution measured in the on cubic centimeter Bask. Add at once 150 cubic centimeters of pure water, either rain water or condensed -team. Pour the mixture into a (lean L r la-- bottle, mix by shaking, and keep stoppered with a rubber stopper to avoid loss i f strength by exp: sure to air. If the mixture is muddy or turhi 1. the water used in diluting was not pure. A Blight turbidity may he neglected. o.J I. I !,-• pit .'\;ition of Mann's alkaline solution in cheese factories. Hoard's Dairyman, vol. 41), No. 41, p. 1200. Fort Atkinson. Wis., Nov. 12, 1909. U. S. Dept. of Agriculture. Plate I. z z < * — < m * t- 05 Q uj O I c needed, etc. If the milk Bhowed an acidity of 0.21 per cent when raw, then subtract 0.21 from 0.25, which Leaves 0.04 percent. In this case, since the milk is riper to atari with, less acid will need to be added; only four-ninths of a pound id for each 100 pounds of milk will be accessary to bring the acid- ity up from 0.21 to 0.25 per cent. In any case the weight in pounds .. ,. .. 0.25 acidity of raw milk weight of milk. «•! acid required is equal to =^ X — «^ — .09 ' x LOO • ,. r .„ weight of milk , . , or 0.25 acidity of raw milk x- Q n Stated in words the rule is, divide the weight of milk by 9 and multiply by 0.25 minus the acidity of the raw milk. The following table shows the amount, in pounds, <>f normal acid required to be added for each loo pounds of milk when the acidity of the latter before pasteurizing is 0.15, and for each one-hundredth increase up to 0.27: Table 14. — Weight of normal acid required to be added/or each 100 pounds of milk. Weight of Acidity of normal Aciditv of milk when arid added milk nfter pasteur- to 1(H) the addi- ized. jKMinds of milk. tion of acid. Per cent. Pounds. Per cent. o. us 1.11 0.25 .16 1.00 .25 .17 n .25 .18 :: .25 .19 .66 .25 .20 .55 .25 .21 .44 .25 .2l> . 83 .25 .22 .25 .24 .11 .25 .11 . 38 .11 .27 .11 Where milk appears to be of, say. ( ) . 1 7 "> per cent acidity when n •< i ived, it is treated as if it were at 0.17 percent, dropping the 0.005 out of the calculation. The following table, conveniently posted, may aid in calculating the weight of acid required for any weight of milk at any acidity: PREPARATION OF NORMAL HYDROCHLORIC ACID. 35 Table L5. Weight of normal hydrochloric acid required for stated quantities oj milk at stated aridities. Hydrochloric acid required when acidity is Weteht of milk. 0.27 tO 0.24. 0.23. 0.22. 051. 0.20. 0.19. 0.1S. 0.17. 0.16. 0.16. 0.14. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. 10, (XX) ll.l 33. 3 44.4 55.5 till, (i 77.7 Ss. s 100.0 111. 1 L22.0 9,000 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 1(H). 1) L10.0 8,000 8.9 17.8 26.7 35.6 44.4 53.3 62.2 71.1 80.0 88. 9 97.8 7,000 7.8 15.5 23.3 31.1 3S.9 46.7 54.4 62.2 70.0 77.8 85. 6 6,000 6.7 13.3 20.0 26.7 33.3 40.0 46.7 53.3 60.0 66.7 73.3 5,000 5.6 11.1 16.7 22.2 27.8 33.3 38.9 44.4 50.0 55. 5 61.1 4,000 4.4 8.9 13.3 17.8 22.2 26.7 31.1 35.5 40.0 44.4 48.9 3,000 3.3 6.7 10.0 13.3 16.7 20.0 23.3 26.6 30.0 33.3 36.7 2,000 2.2 4.4 6.7 8.9 11.0 13.3 15.6 17.8 20.0 22.2 24.4 1,000 1.1 2.2 3.3 4.4 5.5 6.7 7.8 8.9 10.0 11.1 12.2 IKK) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 800 .9 1.8 2.7 3.6 4.4 5.3 6.2 7.1 8.0 8.9 9.8 700 .8 1.6 2.3 3.1 3.9 4.7 5.4 6.2 7.0 7.8 8.6 600 .7 1.3 2.0 2.7 3.3 4.0 4.7 5.3 6.0 6.7 7.3 500 .6 1.1 1.7 2.2 2.8 3.3 3.9 4.4 5.0 5.6 6.1 400 .5 .9 1.3 1.8 2.2 2.7 3.1 3.6 4.0 4.4 4.9 300 .4 .7 1.0 1.3 1.7 2.0 2.3 2.7 3.0 3.3 3.7 200 .2 .4 .7 .9 1.1 1.3 1.6 1.8 2.0 2.2 2.4 100 .1 .2 .3 .4 .6 .7 .8 .9 1.0 1.1 1.2 75 .08 .17 .25 .34 .42 .50 .60 .67 .75 .83 .92 50 .06 .11 .17 .22 .28 .33 .39 .44 .50 .56 .61 25 .03 .06 .09 .11 .14 .16 .19 .22 .25 .28 .31 To find how much normal hydrochloric acid will be needed to raise 6,754 pounds, for example, of milk of 0.17 per cent acidity to 0.25 per cent acidity, take from the table the figure given under 0.17, opposite 6,000, which is 53.3; add to this the figure opposite 700, which is 6.2; then add the figure opposite 50, which is 0.44; the total gives the number of pounds of acid required, namely, 59.9 pounds. PREPARATION OF NORMAL HYDROCHLORIC ACID IN THE CHEESE FACTORY. Chemically pure hydrochloric-acid solution, as purchased in carboys containing about 120 pounds each, contains about 40 per cent by weight of hydrochloric acid and 60 per cent of water, and costs about 7 cents a pound. Its strength varies somewhat, and it must be diluted with water before it can be added to milk in this process. The preparation of normal-strength acid used in cheesemaking is carried on at the cheese factory in two steps, as follows: First step. — Kemove the wooden cap from the top of a fresh carboy of acid and loosen the glass plug in the neck by tapping it on different sides very gently with a piece of wood (not metal) until it can be drawn out readily with the hand. Set an empty carboy alongside the newly opened carboy. Fill both limbs of a glass siphon with water, removing all air bubbles, and insert the two limbs into the carboys at once, as shown in Plate IV. When the siphon is in place, as shown in the lower figure, the acid will flow from the full carboy into the other until in about half an hour each is practically half full. Xow fill up OHEDDAB ( ill.!. si: I BOM PAS1 BUBIZBD MIl.K. each carboy nearly to the neck with water. Leaving -pace enough beneath the neck to permit mixing the contents readily by Bhaking. Tip each carboy up on one edge and rock vigorously for about five minutes with the stopper out to induce thorough mixing. The liquid gets Blightly wanner <»n mixing, and il 18 stoppered and Jei'l to -land OVemighl tO COOl and i- then called "•dilute*' acid. To determine how much further each carboy of dilute acid requires to be diluted with water to make it exactly "normal" iii strength, set up the burette used in Mann-'- test, but fill it with normal alkali solu- tion, which is 10 times as Btrong as that used in testing milk. I a _' cubic centimeter pipette, transfer exactly 2 cubic centimete the dilute acid from the carboy to the porcelain cup containing a Little pure water, letting the pipette drain into the cup half a minute by the watch and blowing OUt the la-t drop of acid from the tip into the cup. Now add one or two drops of indicator and after reading the Level of alkali in the burette, draw out the alkali from the burette, precisely as in testing milk, rapidly at first, Later by single drops while Bhaking the cup in a circle until the last drop added produces a distinctly pink color which remains throughout the entire Liquid after thorough mix- ing. Read and record the volume of alkali solution used. Kinse out the cup, lill up the burette, shake up the acid in the carboy for a minute and test another 2 cubic centimeters of the acid for the sake of accuracy. If the contents of the carboy were thoroughly mixed at first, the two titrations will agree closely, not differing by more than 0.20 cubic centimeter. If they do not agree, the carboy contents were probably not well mixed at first, and should be given another very thorough Bhaking for five minutes, after which the titration- are repeated. Once thoroughly mixed the acid and water remain mixed, and never need in be shaken again. Suppose that in the two tests the 2 cubic centimeters of acid required 11 and 11.2 cubic centimeters of normal alkali to produce the pink color, the average being 11.1 cubic centimeters. Divide the volume of alkali by 2 the volume of acid used-— which gives in this _J_ « 5.55. Tin- means that the acid i- 5.55 time- as Btrong a- it should be for normal acid, and that it must be diluted to tune- it- volume with water to make it exactly normal in strength. The work described above i- performed once on each carboy of dilute acid before Using it for cheesemaking, and the object i- to get the figun in tlii- case) which shows how much too Btrong the acid is, and how much it mu-t be diluted to make it normal in strength. Hi />. The Becond Btep consists in diluting up, each day, as much of the acid as will be needed for the milk on that day. This Bul. 165, Bureau of Ammal Industry, U. S. Dept. of Agriculture. Plate IV. FULL CARBOY OF HYDROCHLORIC ACID EHPTY CARBOY Transferring Acid from Full to Empty Carboy by Means of Siphon. I thy, U. S. Dept. of Agriculture. Plate V. DIRECTIONS FOR PASTEURIZING AND ACIDULATING All IK. 37 is performed as follows: Having determined thai the dilute acid is 5.55 times Btronger than normal, the acid is further diluted for use each day, adding 1 volume of acid to 4.55 volumes of water, thus making the total volume 5.55 times as great as the acid used. To do this, measure out any convenient volume (say 500 cubic centimeters for about 2,500 pounds of milk) of the acid in a glass cylinder and add it to 4.55 times its volume of water (in this case 500x4.55 = 2/275 cubic centimeters water). The acid should always be measured, but if more convenient the water can be weighed in pounds if it is remembered that 453 cubic centimeters of water weigh 2 275 1 pound. In this case ' =5.02 pounds of water needed. The acid and w T ater can be mixed in the acidulator or in a w r ooden pail, or in a bright tin pail, if the water is put in first and the acid added later. After the proper amounts of acid and water have been poured into the acidulator, they should be thoroughly mixed at once by stirring with a w r ooden paddle, and once thoroughly mixed the normal acid is always ready for use. Of course the acid should not be handled in galvanized iron or aluminum vessels, as it will rust them. The undiluted acid will also discolor tinware and should be measured in the glass cylinder, as directed. The " dilute" acid is drawn from the carboy into a gallon glass bottle through a glass siphon, which is first filled with water. The water used in the siphon is so small in volume — about 1 per cent of a gallon — that it does not noticeably affect the strength of the acid. There is nothing difficult about the preparation of normal-strength hydrochloric acid lor use in cheese making, and anyone who knows how to titrate milk for acidity can learn to do this also. To test the cor- rectness of the work when completed, transfer two cubic centimeters of the acid with a pipette from the acidulator to the porcelain cup, and titrate it with the normal alkali in the burette. The volume of alkali required should be between 1.9 cubic centimeters and 2.1 cubic centimeters, or, better, exactly equal to the volume of acid used. The degree of accuracy required in this whole process is very easily attained, as quite satisfactory results will be obtained in acidulating milk if the normal acid used is anywhere between 0.95 and 1.05 normal. GENERAL DIRECTIONS FOR PASTEURIZING AND ACIDULATING MILK. The method described is well adapted for use in a large factory. At a factory handling two to three large vats of milk daily two men should be employed. The inspection and weighing of milk at the intake is performed by one man while the other makes the determi- tions of acidity and runs the pasteurizer. After the milk is all in and pasteurized the two men work together, heating up the vats, I DDAB (in i BE I 'BOM PASTBUBIZEJD MILK. adding the starter, color, and rennet to the vats at Least 10 or 15 min- utes apart. They cut 1 1 1 < - curds in the Bame order, each l'.") minutes after the rennet has been added, and -tart the agitators in cadi curd on as cut. The vate arc heated up and the whej is drawn from the vats in the same order, I oth men working together in putting the curds on the rack, finishing each vat of curd in time to handle the next . If more than three vat- are handled in one factory, additional help will be needed, especially for bandaging hoops, turning cheese, and other labor. Where only one vat of milk is handled daily, the milk is run first into the receiving vat, from which it flows into the pasteurizer, through the cooler, and into the chei If two vats of milk are handled daily, the first milk received may he run into one cheese vat, from which it is pasteurized into the other cheese vat, while the milk received later is run into the Bteel receiving vat, from which it is pasteurized into the second cheese vat. If three or more vats of milk are handled daily, the receiving vat and the first cheese vat are filled alternately with milk from the in- take, and alternately emptied through the pasteurizer into the other cheese vats. It is only necessary to Bee to it that the Last vat filled from the intake shall he the receiving vat in order that this last milk may he run into one of the cheese vats after pasteurization. One re- ceiving vat is needed in addition to the necessary cheese vats wherever this process is used. MAKING READY TO PASTEURIZE. Since pasteurization is essentially a cleaning process, care should be taken to keep the make room, the vats, machinery, etc., and every- thing with which the pasteurized milk comes in contact as clean as possible. Although milk Hows intermittently from the weigh cans, it is de- sirable that the pasteurizer, once started, shall run continuously, with a Bteady milk supply, and for this purpose a receiving vat i- pro- vided. The milk should he run into the receiving vat through a strainer which will remove all Hie-, straw, etc.. and which can not by accident fail t<» work properly. Such a strainer i- shown in Plate Y. It i- set up by slipping a piece of seamless cheese bandage over the wooden frame of the vat -trainer and placing the metal part on top. The metal part collect- all Large piece- of dirt and prevent- the milk from Bplashing over the Bide. The two thicknesses of cheese- cloth effectually remove liner particles of dirt. This arrangement has been used in this series of experiment- for about two years and is heartily recommended. Of course the cloth -hould be scalded daily. OPERATION OF THE PASTBXJBIZEB. 39 The weigh can, conductors, receiving vat, and pasteurizer should be washed daily, immediately after use, and again rinsed with clear hot water before use, if necessary. The pasteurizer and cooler and the connecting pipes should be washed thoroughly daily. .lust before starting the pasteurizer each morning the operator should rinse nut the cheese vat and steam it by running steam into the jacket. The pasteurizer and delivery pipes, especially those parts which are in contact with the cooled pasteurized milk, should be also scalded < li- st earned. This can be done by running a couple of pails of hot water into the heating compartment, heating it there to 180° or higher, and running it over the cooler without having any cold w T ater inside the cooler. Where only one vat of milk is being pasteurized, the acidulator may be set on the edge of the vat, but to avoid moving it, wiien several vats of milk are handled daily, the acidulator should be set near the pasteurizer and the acidulated milk run into the different vats through a movable conductor, as shown in Plate III. STARTING AND STOPPING THE PASTEURIZER. When milk enough has been received to insure a continuous supply for the pasteurizer, the latter may be started. First, see that everything is in place and that the pump supplying water for cooling is running. Set the pasteurizer in motion, turn on a little steam, and run enough milk into the heating compartment nearly to fill it so as to register its temperature on the naked glass bulb of the thermometer placed near the exit to the cooler. Do not allow any milk at all to run into the cooler. If any does by accident, draw it out and scald the cooler with a pail of hot water. Open the steam valve to the full running capacity. When the thermometer in the milk registers about 155° start the milk supply again and adjust so that the thermometer stands at 162° at the exit from the heater. Use care to see that no milk at all is allowed to run to the cooler at a temperature below 160°. If any irregularity occurs in starting, it is much better that the first milk should be heated higher than 160°, even up to 180°, rather than that any portion should pass over into the cheese vat without reaching 1 60°. It will do no harm at all if for a few minutes at first milk at 170° or 180° passes over into the cooler, because this milk will at least be thoroughly pasteurized, but if milk at 140°, or any temperature below 160°, passes over it may carry over harmful bacteria which may injure the entire vat of cheese. A file mark on the steam-valve handle is a great help in quickly adjust- ing the steam supply to the right point. Once adjusted, and with steady milk and steam supply, the pasteur- izing temperature remains nearly constant and requires only momen- In CHiM'Ai: cm. i.si. ri:...M PA8TBUBIZED MILK. ia iy inspection <-\ ery few minutes. No doubt an automatic tempera- ture-controlling device < -< » » 1 1* 1 be used to advantage here. Although the thermometer now supplied with some forms of i- metal jacketed 1<> prevent breakage, yet in all the experiments here reported this metal-cased thermometer was found to register more slo* ly than a naked glass-bulbed thermometer, sel in a rubber stopper, The latter kind has been in use two years without breaking and is therefore preferred. In stopping tlit* pasteurizer for any reason, the operator should remember to st:>]> the acidulator first, then the milk supply, and last of all the Bteam. If the stoppage is for 1 < • 1 1 lt . as at the end of the day's run. the hot milk in the heating compartment is drawn out in a pail (its temperature ^1 »< m l the vat. The milk in the cooler is also drained and rinsed, if desired, into the vat . The water Bupply for cooling must be ample so that a thermometer placed in the milk flowing from the cooler is not above 85 c at any time, and preferably at 80° or lower. since the milk in the vat can easily be heated to 85° 86? for setting with rennet, but can not BO Well he set, or easily cooled, if ahove .S(j°. STAIMI.M; AND STOPPING THE A( IIKLATOR. As Boon as the pasteurizer has he. mi Btarted and regulated the pinchcock at the acidulator is opened, allowing one or more small streams of hydrochloric acid to run into the milk. The height of the liquid in the acidulator should be marked on the glass BCale with a pencil or string, when starting, and another mark placed lower down on the scale t'> show how much acid is to he drawn out for that vat of milk. By this means the operator can see from any part of the room when the acidulator is ready to lie B topped. Always stop the acidulator before Btopping the milk. THE USE OF BACTERIAL STARTER IN THE NEW PROCESS. Tin: REASON FOB ADDING BTABTEB IN MAKING LAsTLl Ll/.Lh-M ILK ( REESE . The addition of the required amount of hydrochloric acid to milk raises its acidity at once to 0.25 percent, hut does not cause any fur- ther increase of acidity at any time. Of the acid thus added, only about one-fortieth remains in the curd, the rest escaping in the whey. No chemical method has b< * n found for increasing the acidity of a curd on the rack, so that if a. id pi ivs any important part in the cheoc- curing process, it will he necessary to add bacteria to the milk in order to develop the necessary acid in the curd and cheese. A number of THE USE OF BACTI.UIAI. STARTER. 41 experiments were performed in which the milk supply was divided and made up in different vats, using different proportions of starter. The cheese was finally scored by Mr. J. \Y. Moore with the following results: Table 16. — Quality of cheese made from pasteurized milk with varying amounts of starter added. Date, made. 1908. Aug. 17 31 £ept 1 Chees i No." 1076c 1079 1081 L083 1085c 1087 1S89 1091 1093c 1095 1097 1099 1101c 1103 1105 1109c 1111 1113 1115 1117c 1119 1121 1123 1157c 1159 1161 1163 1165c 1167 1169 1170 1173c 1175 1177 U79 1024 1026 Propor- tion of starter. Per cent. None. .3 3.0 5.0 Tempera ture of pasteuri- sation. ;•'. 0. 25 157 .50 157 .75 157 . 25 157 .50 157 .75 157 .25 157 .50 157 .75 157 .25 157 .75 157 .75 157 1.00 157 1.25 157 .75 157 1.00 157 1.25 157 None. 162 .3 162 • 6 162 None. 162 .3 162 .6 162 162 162 162 Flavor. Texture. 40.50 40.50 41.25 42.50 41.00 41.75 41.00 40.25 40.. 50 41.25 42.50 42.75 41.25 42.50 42.25 40.75 42.25 42.50 42.50 39. 50 42.25 41.75 42.25 41.00 41.00 42.50 42. .50 39.00 40.50 42.00 42.50 40.00 41.00 41.00 41 . 50 Sour. Sour. 27.00 27. •_'.-, 27.25 28.00 27.25 27.75 27.25 27.00 27.00 27.00 27.75 28.00 27.00 28.25 27.75 27.00 27.25 27.25 27.75 27.25 27.00 27.25 27.00 27.00 27.00 28.00 28.00 28.50 26.00 27.50 28.00 27.00 26.00 27.00 27.00 Color-cut. Color-cut. 1 "c" In this column indicates raw-milk cheese. These scores may be summarized as follows: Table 17. — Summary of scores in Table 16. Amount of starter. Number of cheeses scored. Average scores. Flavor. Texture. Combined. Per cent. 0. 25 to 0. 30 .5 to .6 .75 1.0 1.25 3 6 6 2 2 40. 83 41.04 41. ^ 42. 04 42. 12 42.37 26.33 27.53 27.54 27.50 27.25 27.37 67. IB C9.18 69.42 69.54 69.37 69.75 12 I SDDAB CHEESE iiaeM PAS I l.i i;l/.i.h mii.k. 'I'll, 68 indicated that the cheese obtained by three-fourths, one, <>r one and ;t quarter per cent Btarter are about equally good, considering both flavor and texture, and the use of three-fourths per cent Btarter has been continued Bince August, 1908, to the present time, with good results. Tin* Btarter used Bhould be first da-- in quality, just beginning to thicken, containing the maximum number <»f lactic acid bacteria in active condition, and free from all objection- able germs or flavors. Only a Btarter above criticism, such as every g 1 cheese maker should know how to prepare, can be used with pasteurized milk. If the starter is :>t all tainted it i- Bure t<» damage the flavor of the cheese ►me extent. With raw, badly tainted milk, especially in warm weather, a Btarter of only fair quality will often greatly improve the quality of a vat of cheese, but pasteurized milk i- freed from practi- cally all taints by the pasteurization, and to such milk only tlie best starter can Bafely be added. The importance of a good Btarter was made apparent when, begin- ning June .». 1910, nine days' make of pasteurized-milk cheese proved to he gassy and oil' flavor, and bacteriological examination of the starter as well as of the cheese demonstrated the presence of the same gas-forming organism in both. Jt was (dear that the organism-- in question did not pass through the pasteurizer, since their thermal death-point was found to be lower than the pasteurization tempera- ture (160°) employed in the process. Therefore there could be no doubt that the improper preparation of milk for propagating "startoline" was the cause <>( the trouble in this case. A PRACTICAL STERILIZES FOR THE CHEESE FACTORY. The essential equipment for propagating a starter i- some Bort of a Sterilizer, an incubator, and a supply of a do/en pint cream bottles which are best provided with fairly tight tin covers about '2 inches dee]). Various different Bterilizers have been recommended, the sim- plest being an inverted tin pail covering the bottles of milk on the Steam table. For use as an incubator, a small covered shotgun can may be Bteamed out daily, and after placing the bottles therein ami adjusting the cover it may be carried to the ice box. the cellar, a hay cooker, or any room of suitable temperature. Where bottle- of -tarter must be handled and carried about there is always some danger of their becoming infected, and this can only be prevented by intelligent work on the part of the operator. On account of it- small >i/.e a culture propagated in a bottle is often called a "startoline," meaning a little Btarter. A combined sterilizer, cooler, and incubator made of galvanized iron ha- been devised, and used in our work during the past year with entire satisfaction. Its use saves time in I'KKIWKA THIN n| I III. SI Mil KK. 43 handling and reduces the danger of contamination to a minimum. It is shown in figure 1 . The apparatus consists of a galvanized-iron container with cover, a movable false bottom, and with steam, water, and drain connections. Where pint bottles are used, the perforated shelf is raised and set on lugs as shown. If quart bottles are used, the perforated bottom is lowered, so thai the top of the bottle always stands at the top of the sterilizer. COVER FALSE BOTTOri-v£ *ROUND COcr r ■96 Cap for mm BOTTLE CAP FOR water bottle: 3 NOTGHE5 £ *i Fig. 1.— Combined sterilizer, cooler, and incubator for cheese-factory starter. PREPARATION OF THE STARTER. The bottles having been cleaned and filled nearly full with the best whole milk obtainable are each covered with a tin cap and set in the sterilizer, together with one bottle of water carrying the ther- mometer. The lid is put on and the steam turned on very slowly at first, by turning handle a. After the thermometer projecting through the small hole in the lid shows that the contents of the bottles are heated to 200° or above, the steam is left running for three quarters of an hour, and then turned off. To cool the bottles of sterilized milk open valve b and slowly run in cold water, which escapes at the overflow c. If the water is turned on by mistake faster than the 1 1 OB BDDAB < HEESE I BOM PAfil BUBIZED .MIl.K. overflow <-an <;ni\ it off, the tin caps will keep it from entering the bottles of milk. When the thermometer Bhowa thai the bottle con- tents are cooled to about To the water may be turned nearly or entirely off. The bottle of "startoline" from the previous day, which has uot yet been opened, is now brought in and a portion* about a tablespoonful by guess, is poured into each bottle of newly Bterilized milk in the apparatus, lifting the tin caps For an instant for this purpose. The n i should be free from drafts, floating dust, or other source of contamination, and the transfer should be made as quickly and carefully as possible. The cap is then replaced and the cover put on. The temperature of the water can be kept between 60 and 70 for a leu bours, and in the evening, in summer, if the weather i- \ cry warm, a piece of ice e;in be added to the water. This daily process of propagating the "startoline" was performed in the cheese factory during the year 1 ( .»11 by Mr. A. T. Bruhn, with entire success, carrying along the same culture of bacteria throughout the year. Each day after inoculating the fresh bottles of milk, the remainder is examined hy pouring out a little in a teaspoon or cup, to he tasted and smelled t-> Bee that it i-> in good condition; 1 ami if so, the remainder in the jar i^ used in making up starter for the next day's cheese vat in the following manner: To prepare starter from this u startoline,*' place in a shotgun can about eight or nine pounds of milk for each thousand received daily, cover up, and heat in a tub or dee]) pail of water by passing steam until the water is boiling and a thermometer in the milk reads at least 1 so . Keep it at this temperature for three-quarters of an hour and then cool by filling the tuh with cold water. A dash stirrer whose handle is slipped through the smallest possible hole cut in the cover i- a convenience and saves opening the can for stirring. When thor- oughly co«»l about 70 add to the contents of the can the remain- ing contents of the "startoline" jar. as Mated above. Stir this well and leave for five or six hours at this temperature, after which it may he put in a cooler place to stand overnight. The general principle on which the temperature of starters, etc.. is regulated is that the starter should ripen only fast enough bo he barely thick, or just getting thick, when required for use next day. If the acidity increases too rapidly at first, the bacteria are kept too Long before use in a highly acid medium, not favorable to their growth, and in general this i> to he avoided. The thickening of the milk at about (i()° or 70 may be taken as an indication that the acidity is in the neighborhood of six-tenths per cent, which is about as high as it ought to go for this purpose. To control the temperature for ripening is not so likely to he troublesome as to avoid getting dirt and foreign bacteria into the •• Btartoline " .»r starter after it has l>e< n once thoroughly sterilized. irtber the quelitj of the .^tai-wr. a bottle of the thickened milk. unshaken and unopened, may .mi | la. »• for .i dft] oi tv . • , . lop. TIMI-: SCHEDULE FOR MAKINH CHEESE. 45 Strictly speaking it is impossible fco Bterilize milk so perfectly .-is to kill all spores by one such beating, and on this account attention should be given bo selecting the host possible milk for starter making. At the beginning of the season a small bottle of bacteria] ■tarter can be obtained from dealers or from a college of agriculture. It is well to begin propagating the starter several dux* before cheese making is to begin, and also to carry along two or more starters from different sources, separately, in order that if one is lost or found unsuitable another may be at hand. METHOD OF MAKING CHEESE BY THE NEW PROCESS. GENERAL ARRANGEMENT OF SCHEDULE. In making cheese by the new method the cheese maker is relieved of a great deal of the uncertainty winch attends cheese making by the ordinary methods. Having inspected the milk at the intake and rejected any that is curdled or otherwise unfit for use, he determines by means of Manns's acid test the acidity of the entire vatful of mixed milk. This may be anywhere from 0.14 to 0.25 per cent, or even a little higher, but if much above 0.28 per cent the milk is likely to curdle and clog the pasteurizer. He then runs the milk through the pasteurizer and adds to the cold milk as it flows into the cheese vat enough dilute hydrochloric acid to raise the acidity of the whole vat to just 0.25 per cent (calculated as lactic acid). Three-quarters per cent of a first-class starter is added, and after heating to 85° the color and rennet are stirred in immediately. The rest of the process is conducted according to a fixed time schedule, which is never varied. The time from adding rennet to hooping the curd is always exactly five hours and fifteen minutes, and the intermediate process is as shown in Table 18. Tins is carried on every day in the season without exception. While it may be found desirable or convenient at some factories to modify somewhat this routine, described below, yet it appears practically certain that whatever routine of operations is adopted at any factory, it can be followed without modification throughout the season. Table 18. — Time schedule for making cheese by the new method. Operation. Time inter- val between operat ons. //. m. 25 15 20 1 25 1 30 1 00 20 Total time after add- ing rennet. Adding rennet Cutting the curd Beginning to heat Turning off steam Placing rack after drawing whey Milling the curd Salting the curd Hooping the curd 777. 25 40 60 25 55 55 15 46 CHEDDAB OHEESE I BOM PAS! EURIZED Mil .K. For example, if the rennet were added to the milk at exactly o'clock the cunl would !><• ready t<> put in 1 1 1<- hoops five hours and fif- teen minutes later, i.e., at 2.15 in the afternoon. As soon, as the rennet is added it is best to have ■ written schedule showing the time when each operation should be performed. Having once learned how to perform each operation in this method of cheese making it is only aar} to do everything in as uniform manner as possible in order to get satisfactory results daily throughout the season. There is never ;m\ need to hurry the process if the milk was overripe at the beginning, because the lactic-acid bacteria are practically all killed by tin 1 pasteurization. The Bame is also true of the gas-forming bacteria, bo there is no time Lost in working gas out of the curd. There is no reason for waiting to ripen the milk at the beginni the process before adding rennet. i \moi:m PROPORTION <>f COLOB i BED i\ L911, wi> i:i:wi.i REQ1 [RED. Color. Throughout the season of 1911 two-thirds of an ounce of a standard make of cheese color per thousand pounds of milk was used, giving the cheese a medium shade of color. These cheeses were shipped into a number of different cities and appeared satisfactory to dealers in all parts of the country, except in Philadelphia, Pa., and Boston, Mass.. where some dealers asked for white and others for highly colored cheese, a- is Bhown by the following extracts from letters. Where more than one extract appears from the same city they are from different dealers. Our market usee white cheese exclusively. ■i. Mm as Use both white and colored. Boston, Ma — \ very light color would not do for this market. Chicago, 111 No comment on color. Fond du Lac, Wis V little too light color. ( leneva, X. Y No comment on color. Marahfield, Wia No comment on color. Minneapolis, Minn No comment on color. New York, N V ( lolor is exactly right. York, X. V should be a trifle higher color. Philadelphia, Pa Eave to have white cheese for Philadelphia. Plymouth, W i- No comment on color. Sheboygan, Wia \ good commercial color, but might stand a iritle more color. Bhebo} gan, Wia No comment on color. llis, M" No comment on color. Washington, I'. I Most of our customers want it colored. Waterloo, Wis No comment on color. "Rennet. The Bame proportion <>f rennet is always used in this process, because the milk is always in the Bame condition as to acidity at the time of adding rennet . and always ripen- equally fast afterwards. Therefore, having once selected the most Buitable proportion <>f rennet, there is no reason for changing it. The use of 2 ounces of ADDING STABTEB, COLOR, \M> RENNET. 47 Hansen's or MarschalTs rennet per thousand pounds of milk is adopted as the best practice, since this quantity produces visible coagulation in 7 minutes, as shown in Table 2, and the curd is in prime condition for cutting in 25 minutes after adding rennet. If the rennet extract is weaker than it should be, such amounts should be used as will cause coagulation in the time stated. If a larger proportion of rennet than 2 ounces per thousand pounds were used, there would hardly be time for the milk to become quiet before visible thickening began, and the curd might be damaged and broken through thickening while still in motion. On the other hand, over two years' experience with the method has shown that there is no need for using a smaller proportion of rennet than 2 ounces. Good cheese can be made with 1 ounce of rennet per thousand pounds of milk, but the coagulation of the milk is unnec- essarily slow. As in regular cheese making, great care must be taken not to measure or dilute rennet extract in any container in which there is present the least trace of cheese color, because the cheese color is strongly alkaline, and rennet loses its coagulating power almost instantly when in contact with alkalies. ADDING STARTER, COLOR, AND RENNET TO THE MILK. The temperature of all the mixed milk after pasteurizing is never above 85° and commonly only 70° to 80°. The acidity may be tested, if desired, and should be just 0.25 per cent, or between 0.24 and 0.26 per cent. Three-quarters of a pound of starter per hun- dredweight of milk in the vat is added immediately through a hair sieve, stirring the milk. The rake is then put in and the vat stirred, while heating up to 85°. The desired amount of color is stirred in, and always, without exception, the rennet is stirred in last of all. The rennet extract measured out for 5,000 pounds of milk should be diluted in a pailful of water. In adding rennet, first stir the milk across the vat the short way, going rapidly from one end of the vat to the other. With the largest-sized vats, two men with rakes may begin at the middle and walk toward the ends while stirring. Then walk back along the vat, adding the diluted rennet from a pail to the milk which is still in vigorous motion, noting on the clock the instant when the rennet first enters the milk. Set down the pail and again stir the milk across the vat the short way, with the rake or rakes, for exactly one minute, in which time the operator should be able to walk up and down the vat three or four times. In this way the smallest as well as the largest vats of milk should be set. Take out the rakes promptly one minute after the rennet entered. Cover the vat at once, and leave undisturbed. No top stirring is necessary or permissible, as the milk begins to thicken almost exactly seven min. 48 CHEDDAB CHEESE PBOM PASTEURIZED MILK. slier adding rennet, before there is any visible cream rising. Follow exactly the directions as to temperature, acidity, and propor- tion of rennet every day in the season. CUTTING, STIBRINGj wi> in. \ I i\o THE CUBD. The curd formed in this process Is always ready to cul exactly 25 minutes after the rennet entered the milk. Therefore as soon as the rennet has been added it is best for the operator to write the entire time schedule, as shown in Table I s . For the rest of the day's work on a paper, or, better, on a blackboard, which can be seen across the room. Some operators may suppose that possibly the curd might l>e cut a little earlier or later, but experience has Bhown that the curd is always in a thoroughly satisfactory condition for cutting just 25 minutes after adding rennet. There is therefore no need for repeated testing of the curd with the finger; it is only necessary to keep an eye on the clock, and follow the t ijne >chedule. In cutting, begin with the horizontal knife and cut lengthwise <>f the vat : t hen use t he vert ical knife across t he vat . cnt t ing alternately toward and away from the operator. Finally cnt Lengthwise, with the vert ical knife. Do not cnt the vat more than once in each direc- t inn, and t ry to do t he cnt t ing in exactly t lie same manner every day. The different cuts should not lap, nor should portions of the curd wider than three-eighths of an inch he left uncut between the knives, except in the following case: In cutting next to the sides of the vat, a- in the first and last cuts in each direction, hold the knife as close to the metal sides of the vat as possible. If the knife doe- not appear wide enough to cnt the remaining curd at the last stroke, cut close to the tin and leave a narrow strip of uncut curd, not at tin 1 edge of the vat, hut between the last cut and the next to the last. This strip will he cut more thoroughly by the knives moving in other directions than if it had been left next the tin. Knives with hlades three-eighths of an inch apart are required for this method. Immediately after cutting put tin 4 agitator hlades in place and Mart them in motion. The curd obtained in this process is so firm and solid that this can always he done safely. Go around the^vat with the hand some t hue during the next 15 minutes, loosening the eurd From the sides, bottom, and corners of the vat. A form of agi- tator which is very satisfactory has one pair of revolving hlades which also move up and down the vat. somewhat resembling the mot i<>n of t he rake. Bxacl ly 15 minutes after cutt big turn steam into the jacket of the vat , and raise the temperat ure gradually during the next 2(1 minui just !!• to 104° — which temperature is maintained until the whey is draw n. Bul. 165, Bureau of Animal Industry, U. S. Dept. of Agriculture. Plate VI. o MISCELLANEOUS OPERATIONS IN CHEESE MAKING. 49 DRAWING THE WIIKY, HATTING, CUTTING, AND TURNING THE 01 RD. The agitator is left running until about t wo minutes before i be \\ bey is to be drawn, when it is removed, and the curd, after settling a few sec- onds, is pushed slowly away from the gate with one or two rakes. The whey strainer is placed inside the vat and the hair sieve below t be gate in the conductor, the gate being opened at such a time as will permit the whey to be out and the first rack to be put in place at the time given in the schedule. When the whey is nearly all out, the gate end of the vat is lowered gradually, and a few seconds later the curd is pushed down toward the gate, leaving the upper third or half of the vat bottom bare and free from whey. In this process the curd is always sufficiently firmed in the whey so as not to need any stirring in the whey or on the rack. With reasonably brisk work the curd can be transferred to the curd cloth on the rack with a curd pail or scoop before it has time to become lumpy on the bottom of the vat. Each pail of curd as it strikes the rack should fall apart loosely and not show the presence of great lumps of curd matted together. Any such lumps should be lightly broken up with the hand, and if many lumps appear it indicates lack of skill and quickness. The curd is piled evenly on the rack about 4 or 5 inches thick, and the top is leveled off with the hand in the usual manner and cov- ered with a curd cloth. More racks if necessary are put in place and the vat is finally covered, leaving the curd to drain. The little curd gauge, made of wood, devised during the course of these experiments is a help in getting the layer of curd of the right thickness and also gives a good square end to the curd, which makes it easier to cut into blocks of uniform shape. (See PI. VI.) Just 15 minutes after the time scheduled for putting in the rack the curd gauge is removed and the cutting of the matted curd into blocks 8 inches square, or 6 by 12 inches is begun. The blocks are turned over immediately after cutting, and again turned 15 minutes later. They are then turned once in 10 minutes, and one hour after drawing the whey are piled two deep, and repiled every 10 minutes until milled. In turning and piling, care is always used to turn the outer cooler surfaces toward the inside, in order that the entire mass of curd may remain at practically uniform temperature throughout, as in ordinary practice. MILLING, SALTING, AND HOOPING THE CURD. Exactly one and a half hours after the whey is drawn the curd is milled. The milled curd is piled along the sides of the vat, so as to drain toward the middle. It is stirred up with the hands from the bottom, turning the pile over about once every 10 minutes after milling, so as to cool it somewhat, prevent matting, and allow free 79994°— Bull. 165—13 i 50 OHBDDAB CHEB8E PBOM PA8TBUBIZBD MILK. drainage. Little or no white whey ever escapee from the curd after nulling or Baiting when made u|> by this process, although some clear w bey or brine does drain nw ay, One bour after milling sail i- thoroughly ini\<'f curd, which amounts practically to 2 pounds per thousand of milk in the spring and early Bummer, and 2] pounds per thousand of milk in the fall, when the yield of cheese per hundredweight of milk is Bomewhat greater. The curd is Btirred overseveral limes during the next 20 minutes, by which time the sail is all dissolved, and the curd, at a temperature of 82° to 86°, is ready to he hooped. Kach hoopful of curd is covered with a cloth and follower as soon as filled, in order to prevent the sur- face of the curd from coolingSO far that, it might fail to close well in the pic— . It is of the utmost importance that every cheese should he well dosed and develop a perfect rind, free from cracks or other openings. Where openings occur mold is sure to enter during the curing pro< and the flavor especially is apt to suffer as a result. PRESSING AND DRESSING THE CHEESE. Throughout the present set of experiments the cheese has heen pressed for about an hour, applying pressure with the hand lever only, and at first only sufficient pressure is used to keep the drippings running from the hoops. After an hour the cheese is dressed and returned to the press, when continuous pressure is put on and it is left for the night. In bandaging the hoops, the usual starched circles are used under the heavy muslin or duck cap cloths, or if it is found that the circles are hard to remove for paraffining they may he left out and the cap cloths left on the cheese until paraflined. The cap cloths, being of heavy cloth, can be stripped ofT rapidly without tearing and washed; in this way they may be used many times. The next morning it is customary, as in cheese factories generally, to look over the cheese, Btraighten any bandages which may be faulty, and turn any crooked cheese over in the press, leaving them until noon to straighten. DRYING, PARAFFINING, AND CUBING. The cheeses when taken from the press are stenciled witli the brand and date of making or a reference number, and placed on shelves in a well- vent dated room to dry on the surface. This room may be as high as 70°. Mere they are turned over once a day. The cheese Bhould be paraffined when 5 to 10 days old. or pos- sibly earlier. The paraffin should be at 220° F., at Least, and better at MISCELLANEOUS OPERATIONS IN OHBESB MAKING. 51 230° to 250° F. The thinnest possible coal of paraffin is the best, and the cheese should be held in the paraffin aboul 5 seconds and then drawn out and left to drain over the vat, OH a rack, until it can bo handled. A thin coating of paraffin is llcxihlc and Jess likely to crack than a thick coating. It is possible to euro this eheose at any temperature between '.l and 75°. When it is desirable to cure the cheese as fast as |><»-il>lr, a temperature of 75° may be used without injury to the quality. However, at this temperature 4 there is considerable shrinkage, and it is necessary to wipe the cheeses occasionally and turn them over to prevent them from getting moldy and sticking to the shelves. At 45° to 55° the cheese cures well, with little shrinkage and a minimum amount of labor. It also cures well when stored at 34° at the age of 1 week and develops little or no mold on the surface, but owing to the extra cost this temperature should only be employed where it is necessary to hold the cheese for a considerable length of time. BRANDING AND SELLING THE CHEESE. In order that customers may be sure that they are getting genuine pasteurized-milk cheese when called for, every cheese should be marked with the words "Pasteurized cheese' 7 running all round the edge of the cheese. All persons making cheese according to the process here described should use such a brand, in order to distinguish this product from the ordinary Cheddar cheese. A large number can be rapidly marked with a rubber stamp or by rolling the cheese over rubber type, set in a board, as shown in figure 2. Narrow strips of wood on each side of the board prevent the cheese from rolling side- wise off the type. In a new style of product uniformity is a quality which consumers and dealers require. It is recommended that the maker of this style of cheese keep back one cheese from each day's make, when shipping, until the consignment has been accepted and paid for by the buyer. The sample cheese can then be sent along with the next shipment without plugging. If necessary, the cheese can be plugged with a trier, and by this means the maker will be able to study any faults which may be observed by the buyer and avoid them in the future. Names of leading cheese dealers who have already received sample shipments of this make of cheese and found it suitable for their trade may be obtained from the authors. Where a maker doubts whether the buyer is giving him fair treat- ment, it is recommended that parts of each day's make be sent to two different dealers, whose criticisms, if any are received, can be compared by the maker at the factory. CHEDDAR CHEESE FROM PASTEURIZED MILK. TESTING CHEESE FOB MOISTURE WHEN DRESSED IN THE HOOP. In making cheese by this process, the green cheese was found to differ very little in moisture content from day to day. as is Bhown in Table 19 Excepting the first day the cheese was made each day in two rats, and each \ at of curd was tested for moisture separately. The determination of moisture in cheese is not recommended as a pari of the daily work in a factory. It is of great value, however, in experimental work, where it is desired to study the effect on their moisture contenl of different methods of handling curds, or the effect of different moisture content on the market value or keeping quality (•I cheese. FlO. -Method of marking cheese. Moisture tests are easily made. It is objectionable, however, to plug a new cheese every day for a moisture test because of the dan- ger of admitting molds, etc., beneath the rind, and it has been found that plugging the green cheese can ho entirely avoided by sampling it at the time it is dressed in the hoop, about one hour after putting it to press. The trier hole made at this time by turning down the bandage and inserting the trier at the side will close entirely over night in the press, leaving the rind perfect. Samples of cheese thus taken from the dressed curd and tested for moisture agreed closely in moisture content with samples taken with a trier from the same cheese the next day. after pressing about twenty hours, as may be seen from Table 19. The moisture tests were all made by heating 10-gram portions of the curd for at least three hours in the Wisconsin hidi-prossurc INCREASED HELD OF CHEESE OBTAINED. 53 steam oven. 1 After three or four hours there is practically no Further loss of weight from Bamples o( Fresh curd in 24 hours' heating. Sam- ples of cured cheese continue to lose weighl with continued heating much more noticeably than Bamples of Fresh curd or green cheese. Tahi.e 19. — Comparison of moisture determination* made on samples taken when was dressed, three-quarters to one hour after pressing, and on samples taken from green cheese, next day, when removed from press. Moisture content when • Moisture content, next day, Dale. was dressa . whtM removed from pre DilTer- enee. First. Second. Average. First. Second. Average. 1911. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. Aug. 15 37.40 37. 5 J 37. ti 1 +0.10 16 38.50 38.60 38.50 39.00 3s. 75 + .15 16 38.50 3 38. 70 38.50 3s. 27 - .43 17 39.10 39.35 38. 6J 3s. 55 - .80 17 38. 90 39.00 38.95 39. 40 :-!'.'. 4 i 39. 4 ) + .45 In 37. B i 37. 75 37. 77 37. 75 37. 95 37. s", + .08 18 42. 25 42. 25 42. 25 41.25 41.40 41. 32 - .93 23 38.80 3S.80 3s. s ) 38.05 38. 4". 38! 21 — . .").") 23 42.25 42. 45 42.35 42.20 42. 1.1 42. 15 - .20 24 39.35 39. 05 39.20 39. 70 40. 3 ) 4 >.().) 24 44. 25 44. 3 ) 44. 27 43.15 43. 3 ) 43. 22 -1.05 25 39.55 39. 70 39. 62 39. 30 39.65 39. 46 - .If, 25 44.10 44.4.3 44. 27 44. 25 44. 95 44. 6 ) + .33 26 38.95 39.10 39.02 :>. S 1 39.00 3s. 90 - .12 26 44.30 44.60 44.45 42. - 1 43.00 42. 9J -1.55 RESULTS OF TWO YEARS" TRIAL OF THE METHOD. INCREASED YIELD OF CHEESE OBTAINED BY THE NEW PROCESS. APPARATUS AND METHODS OF STUDY. In the season 1909-1910 it was found that an increased weight of cheese is regularly obtained after pasteurization as compared with the weight obtained by the regular factory methods. For the pur- pose of accurately studying the yield of cheese in 1911 two scales were used, one of 5,000 pounds' capacity graduated on the beam to one-half pound and one of 300 pounds' capacity graduated on the beam to one-tenth pound. The larger scale was set up permanently in one corner of the make room, and a wooden frame carrying a 300- gallon steel receiving vat was placed upon it. The outlet of the vat is of sanitary metal piping, suspended by wire to the vat in such a way that the pipe and contents are weighed each time with the vat. The frame, vat, and pipe weighed 487^ pounds when empty. The separate weights and the scale on the beam were carefully tested by use of test weights. The entire set of weights agreed among them- selves so closely that no difference could be detected in the equilibrium of the beam when one weight was substituted for another in weighing a load. The error in a single weighing is not over one- quarter of a JFarrington, E. H. A creamery method for the determination of water in butter. Wisconsin Agri- cultural Experiment Station, Bulletin 154. Madison, Sept., 1907. 54 CHEDDAB CHEB8E li:-»M PA8TBUBIZED MILK. pound with large or unaD Loads. Except when weighing the lever is kepi up, thus relieving the knife edges from load and wear. The method of using this apparatus is as follows: The vat being empty with the pipes in place and Btopcocks closed] the supply of milk is run into the vat through a conductor and cloth strainer. The Btrainer and conductor arc then removed, the lever is lowered, and the weight of vat and contents determined. Jt i< our habit to balance the scales exactly, giving neither "Up" nor ••down" weight. The lever is then raised, and the operator climbs up the ladder on the frame to the runboard along the Bide of the vat. With a dipper he stirs the milk continuously and vigorously for 5 or 10 minutes, and continues Btirring while a portion i t the milk is being drawn ou1 for use in one of the experimental cheese vats. The vat and the remain- ing milk are then weighed with the Bams precautions as before, after w hieh another portion of the milk may be drawn off for use in another Vat in the same manner. The precautions mentioned above seemed sufficient to insure that the milk used in the two vats one for ordinary and one for pas- teurized cheese was thoroughly mixed at the time it was drawn from the receiving vat, and that each lot was weighed accurately with a total possible error of not over one-half a pound in a vat of 200 to 2,000 pounds of milk — an error of one-fortieth to one-fourth of 1 per cent, at most. The other new scale mentioned above is a counter scale graduated on the beam to one- tent li of apOUnd and sensitive to one-twentieth of a pound with any load up t i 200 pounds. This was used for weighing the cheese throughout the work lure described. The set of weights used with this Bcale. agreed among themselves and with the test weights mentioned above in the description of the other scale. With the smaller scale. 20 to 200 pounds of cheese could readily be weighed with an error of not over 0.05 of a pound, or 0.25 per cent, at most. On 68 days during the season of 1911 the receiving vat of milk was divided into two accurately weighed portions fortius exper- iment. One of these was pasteurized and made up into cheese by the new method, the othei portion was made ii]> into chee-e by regular, factory methods. The cheese was I3j inches in diameter by J inches high, the "daisy" Bize. The green cheese was always weighed as quickly a- possible after being removed from the hoops. 'Die daily record of weights of milk used and of cheese obtained, and the per cent of increased yield which resulted from pasteurization, are shown in Table 20. IXCHKASKD VIK1.D OF C'HKKSK OMTAINKI). 55 Table 20.- Increased yield of gran elms,' obtained by the /"" method from pasteur- ized milk. Pasteurized milk. Raw milk. <;;iin by Proportion of tarter used. Date made. Yield of Yield of pasteur- cheese cheese ized Pas- Milk- Green per hun- Milk Green per hun- milk. Raw. used. cheese. dred- used. cheese. dred- teur- ised. weight weight of milk. of milk. 1911 Pounds. Pounds. Pounds. Pounds. Pounds. Pounds. Per cent. Per ct. Pet a. Feb. 23 538. 53.20 9.89 380.0 35.40 9.31 6.23 0.75 0.00 24 504. 5 51.00 10.11 380.0 36.60 9.63 4.98 .75 .00 27 1,026.5 106.20 10.35 600.0 57.80 9.63 7.48 .75 .00 28 800.0 82.20 10.27 400.0 38.30 9.57 7.31 .75 .75 Mar. 1 350.0 35.40 10.11 510.0 50.20 9.84 2.75 .75 1.50 2 389.5 39.00 10.01 628.0 59.70 9.51 6.61 .75 .75 3 340.0 35.00 10.29 522,0 52.30 10.02 2.79 .75 1.50 7 855.0 88.20 10.32 380.0 38.40 10.11 2.08 .75 2.00 8 590.0 60.70 10.29 388.5 39.30 10.12 1.68 .75 1.50 9 418.0 42.80 10.24 417.5 41.00 9.82 4.27 .75 1.00 10 442.0 44.70 10.11 700.0 66.40 9.49 6.53 .75 .00 13 1, 166. 122.00 10.46 275.0 25.70 9.34 12.00 .75 .00 14 956.0 103.40 10.81 260.0 25.80 9.92 8.97 .75 .75 15 570.5 58.10 10.18 380.0 37.50 9.87 3.14 .75 .75 16 531.5 56.90 10.71 359.0 37.40 10.42 2.78 .75 2.00 17 395. 41.20 10.43 396.0 39.80 10.05 3.78 .75 2.50 20 1,344.0 136.00 10.12 384.0 36.60 9.53 6.19 .75 .00 21 570.0 56.40 9.89 378.0 35.30 9.34 5.89 .75 .00 22 362.5 36.00 9.93 542.0 51.80 9.56 3.87 .75 1.67 Apr. 5 585.0 60.80 10.39 390.0 37.70 9.67 7.45 .75 .75 7 508.0 51.15 10.07 339.5 32.50 9.57 5.22 .75 .75 11 549.0 55.00 10.02 549.0 52.60 9.58 4.59 .75 .75 13 364.0 35.70 9.81 364.0 34.55 9.49 3. 37 .75 .75 17 800.0 80.25 10.03 600.0 55.50 9.25 8.43 .75 .00 18 720.0 71.15 9.88 540.0 49.80 9.22 7.16 .75 .00 24 1,254.0 122. 80 9.79 660.0 61.90 9.38 4.37 .75 .75 27 570.0 55.30 9.70 380.0 35.70 9.39 3.30 .75 .75 28 420.0 40.85 9.73 420.0 40.05 9.54 1.99 .75 .75 May 2 636.0 65.05 10.23 424.0 42.00 9.91 3.23 .75 .75 3 558.0 54.30 9.73 372.0 35.55 9.56 1.81 .75 . 75 8 1,693.0 158. 15 9.34 800.0 70.95 8.87 5.30 .75 . 75 10 798.0 77.60 9.72 798.0 73.70 9.24 5.19 .75 . 7.5 15 1,587.0 161.60 10.18 800.0 76.90 9.61 5.93 .75 . 75 17 1.088.5 109. 00 10.01 800.0 76.60 9.57 4.60 .75 .75 22 1.223.0 129.40 10.58 800.0 78.20 9.77 8.29 .75 . 75 25 851.0 87.00 10.22 800.0 78.80 9.85 3.76 .75 . 75 29 1,315.0 138. 60 10.54 800.0 80.20 10.02 5.29 .75 .75 June 1 798.0 83.50 10.46 800.0 83.10 10.39 .67 .75 . 75 2 799.5 82.85 10.36 800.0 79.50 9.94 4.23 .75 .75 7 790.5 79.65 10.07 800.0 76.60 9.57 5.22 .75 . 75 9 800.0 82.30 10.29 800.0 78.15 9.77 5.32 .75 .75 13 1,090.0 119. 70 10.98 800.0 80.20 10.02 9.58 .75 .00 15 795.0 85.50 10.75 800.0 80.70 10.09 6.54 .75 .75 16 800.0 83.45 10. 43 800.0 78.95 9.87 5.67 .75 .75 19 810.0 87.60 10.81 800.0 79.65 9.96 8.54 .75 .00 21 798.5 81.75 10.24 800.0 77.70 9.71 5.46 .75 .75 26 770.0 80.65 10.47 770.0 75.45 9.80 6.84 .75 .00 27 801.0 83. 50 10.42 800.0 79.00 9.88 5.46 .75 . 75 28 801.5 85.90 10.73 800.0 82.00 10.25 4.68 .75 .75 July 3 1, 234. 122. 75 9.95 800.0 72. 35 9.04 10.07 .75 .00 6 995.0 102.45 10.30 660.0 66.10 10.02 2.79 .75 .7.5 8 1,068.0 108. 50 10.16 660.0 62.80 9.52 6.72 .75 .00 10 1,064.5 107. 30 10.08 800. 74.35 9.29 8.50 .75 .00 11 914.0 93.50 10.23 660.0 63.65 9.64 6.12 .75 .00 12 873.0 93. 15 10.67 800.0 78.20 9.77 9.21 .75 .75 24 1,195.0 125.10 10.47 600.0 58.20 9.70 7.94 .75 . 75 26 1,099.0 118.32 10.77 190.0 19. 32 0.17 5.90 .75 .00 Aug. 29 294.5 31.58 10.72 290.0 30.50 10.52 1.90 .75 .75 30 344.0 35.82 10.41 340.0 34.05 10.01 4.00 .75 .75 Sept. 1 322.0 34.10 10.59 320.0 32. 60 10.19 3.92 .75 .75 5 291.5 31.00 10.63 292.0 29.65 10.15 4.73 .75 . 75 6 276.0 28.95 10.49 275.0 27.20 9.89 6.46 .75 .75 7 286.5 31.03 10.83 286.5 29.48 10.29 5.24 .75 . 75 8 292.0 31.50 10.79 292.0 30.25 10.36 4.14 .75 .75 20 263.0 29.15 11.08 263.0 27.80 10.57 4.82 .75 .75 22 265.0 29.20 11.02 266.5 28.05 10.52 4.75 .75 .75 25 748.0 83.90 11.22 250.0 26.40 10.56 6.25 .75 .75 Oct. 2 700.5 79.25 11.31 420.0 45.10 10.74 5.31 .75 .75 A vera 3 ge. . 251.0 27.75 11.05 250.0 26.25 10.50 5.24 .75 .75 10. 7 9.815 5.374 " CHKDDAB CHSE8B PBOM PASTBUBIZBD MH.K. It w ; ll be noted thai every day in the season there waa a greater a ield <»f cheese from the pasteurized milk. Prom 250 to 1 .Too pounds of milk were bandied in each rat. The average yield of green ch< from raw milk was 9.815 pounds ami from pasteurized milk l> pounds per hundred pounds of milk. The daily increase in yield ranged from 0.6 per cent t<> 12 per rent, and in 50 casea (72 per cent lay between •': and 8 per cent, while the average increase in yield l>y the new pmci^ on 69 day- was ~>.:;7 per cent. 1 On h") days the same proportion <»f >kim milk starter tl fourths per <-<-nt was uaed in both the raw and the pasteurized milk. In the raw milk none vtaa used on 16 days, and on s days l tu 2\ per cent ion the average 1.71 per cent was used, while in every case the pasteurized milk received three-fourths per cent Btarter. If the use of starter affects the yield of cheese, the average yield from the pasteurized milk on in day- was raised about three- fourths per cent, while the average yield from raw milk was i on 8 days about 1.71 pet- cent. These two effects offset each other in the table, giving a slight advantage to the yield from the raw milk, so that the final average figure ")..*>7 per cent representing the aver- :ain in yield of green cheese by the new process, i> no higher and possibly a trifle lower than it would have heen if equal proportions of Btarter had heen used in all Among the 17 cases in Table *J(> in which no starter was used in the raw-milk vat. the average gain in the pasteorized-milk vat. using three-fourths per cent Btarter, was 7.48 per cent ; and in B casea where more than three-fourths per cent Btarter was uaed in the raw milk, the average gain in yield in the pasteurized-milk vat was '■'> per cent. From thia it would appear that the proportion of starter used does notably affect the yield of cheese, contrary to BOme recent >tateinent>. 2 ;» B FOB SYSTEMATIC ERRORS IN EXPERIMENTS ON" YIELD OF CHI I The presence of systematic errors was carefully guarded against in the daily work on the yield of cheese. Before dividing the milk from the receiving vat for use in the two make vats, the milk was first thoroughly stirred for i to 10 minutes, as already stated, and the Btir- ring was continued while the milk was running out. The portion of milk drawn out first was commonly used for making the raw-milk cheese, but sometime-, as on March 8, :•. in. 17. lM. 22, and April 7, 11. 17. 18, and May 10, the portion drawn first was used for making the past urized-milk cheese. The average gain in yield through pas- i Both the medial) and the mode lie l>etw- . r i-ent. The mode is the class which 000O1 nqueney; U the magnitude at the middle of the series from larger B.DftVBOp Principles of Breeding." by E. Daven- of cheese making. New York, INCREASED HELD OF CHEESE OBTAINED. 57 teuiization on these 1 1 days was 5.15 per cent, so nearly equal to the general average of 5.37 per cent (sec Table 20) as to indicate thai the gain in yield is not due to any difference in composition of the milk when divided into two lots. Carefully tested thermometers and the same pair of curd knives were used in every vat. Usually the vat of pasteurized milk was set first with rennet, and the vat of raw milk 5 minutes later. The two vats were placed near each other, and conditions were such that one operator could stir them both at once, if desired. On 11 days, April IS, 24, 27, May S, 10, 15, 17, August 29, 30, September 1, and October 2, the rennet was added to the raw milk first, and to the pasteurized milk 5 minutes later. The average gain in yield on the 11 days was 4.63 per cent, indicating that the order of setting the vats had nothing to do with the gain in } r ield. In order to ascertain what per cent of unavoidable error enters into the measurement of yield of cheese, a special experiment w T as performed on 34 days. Each day, with all of the usual precautions, two lots of milk drawn from the receiving vat were run through the pasteurizer, one after the other, and made up into cheese in separate vats marked (C) and (D) standing near each other, and handled by the same oper- ator (Mr. Bruhn). The vats were heated and set exactly 5 minutes apart by the w T atch, and the time schedule for each vat was strictly followed in every detail. The same curd knives and thermometer were used in both vats. The pasteurizer and cooler are ahvays rinsed with hot water at the beginning of the first run, but are wet with adhering milk at the close of the run just before beginning the second run. Thus the actual weight of milk in the first vat might be slightly less than it should be. To avoid this source of error, the pasteurizer and cooler were allowed to drain each time into the vat for several minutes (until the stream of milk broke into single drops), and then the metal surfaces were carefully rinsed with two measured portions of clean water. Thus the surfaces of the pasteurizer and cooler w r ere wet with water at the beginning of the second run as w T eft as the first. The milk content of the rinsings (see Table 21) was found to be very small and uniform, amounting to about 0.8 of a pound of milk each time, which if it were all lost from one vat but not the other would cause a difference of yield of cheese from a 500-pound lot of milk (as in Table 22) of about 0.16 per cent. In order to avoid this source of error entirely, the rinsings from both runs were either thrown away, as on the first 15 days listed in Table 22, or the rinsings after each run were added to the respective vats, as on the last 19 days. 58 OHEDDAB CHEESE FROM PA8TEUBIZED MH.K. Tabu 2] Milk content of rii and cooler. at . hi of •• In rinsings. -•it of milk In tngfl 1911. Pmt/mia, Pounds. Pounds. The yield of cheese obtained in duplicate vats thus handled was never exactly equal and varied on the average for 33 day- by 0.585 per cent of the weight of the cheese, as shown in Table 22. The milk in Vat C was drawn first from the receiving vat, and was pasteur- ized and set first in all cases except where otherwise noted. Tabi i. 22. Variation m yield of cheese from duplicate vats of pasteurized milk. Ratio of Vat I). Dtflar enee m Weigh! Weight milk Weight yield of the two of milk of green per cut. of milk J*T CWt. of milk. cheese. of milk. Vat Vat 1911 1'nunds. Pounds. Pou nds. C. D. Pou nds. Pounds. Pounds. Per cent. Mar. 23 430.0 1 1 42.55 0.11 390.0 9.949 1 1 390.0 39.10 iaoo6 .77 27 36.10 1 3 1,125.0 109.20 • a 10. 457 1 2J 10. 537 59. 10 10. 102 i; i 390.0 39.45 10.115 .13 30 50.10 10.121 ii l 330.0 33.50 10.151 .30 31 540.0 10.038 360.0 36.15 10.042 .04 Apr. 4 585. ttO. 50 10. 342 ii l 390.0 10.307 6 54. 15 10. 140 lj l 37. 35 •3.46 10 1,080.0 106.30 9 842 3 1 36a 35.65 .62 12 555.0 10.036 li 1 370.0 37.60 10. 162 14 38a 38. 10 10. 026 1 1 - 10.105 1" 400.0 40.30 10.075 1 1 4O0.0 10. 150 .74 - 370. 1 11 55..0 55.40 .50 21 a 87.00 1 U 570.0 55.45 4 21 Ml 41.00 - .25 26 3m o 36. 20 1 U, 555.0 54.35 .09 May 4 42. lo 10.024 1 1 420.0 12 " 10.119 .95 5 51.40 n i 354.0 D 4a 65 i n 612.0 11 410.0 41.50 10. 122 l i 410.0 41. Ml In 195 12 795.0 i i laooo 1.59 800.0 10.037 i i Boao In (161 .44 is 10.633 l i 10.450 1.75 600.0 W.387 i i 10.325 .41 23 i i 10.625 .39 24 612.25 10.510 i l 612.25 ln.Ml 1.24 30 600.0 61.30 10.217 i l eoao in. 125 .91 600.0 10.350 i i 600.0 10.353 .03 June 6 Hi. 146 i l .91 B l l 10.308 .49 ii 600. i l 62. 15 10.358 .21 17 62.71 in 160 i i 63. 1 1 ■Jii 600.0 60.30 111 (Ml i i ..(HI II 60.90 10.150 .99 - 10.105 536.37 10. 149 '.5S5 1 The recall foe Apr. 6 Is omitted In computing i « of abnormal conditions. Among the 34 days' results obtained during the season, as shown ible 22, the difference in yield between duplicate vats exceeded per cent in only one case. On this day there was unusual difficulty in the work because ^( unexpected failure of the supply of DISCUSSION OF \\i;i\TKi.\ IN HELD. 59 water for cooling, and, although the direct cause of the exceptionally high figure (3.46 per cent) can not be directly traced, i1 -reins likely that sonic gross error occurred, which was avoided on the other days. Therefore this figure (U)v April 6) is omitted from the general average. On 28 days (82 per cent of all cases) the variation in yield between duplicate vats lay below 1 per cent and on 33 days (omitting April (i) it averaged 0.584 per cent. For present purposes, therefore, it may be considered thai the figure 5.37 per cent, from Table 20, representing the average increased yield of green cheese obtained through pasteuriza- tion, is correct within 0.58 per cent, or about one-ninth of its value. The yield of cheese from pasteurized milk is thus capable of meas- urement with an average difference between duplicate determina- tions of 0.6 per cent of the amount determined. This degree of accuracy in manipulation is comparable with that attained in many analytical chemical processes, in which a limit of 1 per cent of the amount determined is commonly set as the maximum allowable difference between duplicates. The principal cause for the difference of 0.60 per cent in the yield in making duplicate vats of cheese does not lie in the weighing of the milk or cheese, because with the scales employed both the milk used and the cheese obtained therefrom could be weighed with an error of not over 0.10 per cent. The per cent of difference in yield was not reduced when the weight of milk handled was increased. It appears likely, therefore, that there are small unavoidable differences caused by the size of the cubes or in the manipulation of the milk and curd which cause an average difference in yield of from 0.50 to 0.60 per cent between duplicate vats. An effort was made so far as time permitted to determine w T hether any one of several causes was regularly or chiefly responsible for this average difference in the yield. The stirring of the vats was done by hand in all cases where the weight of milk in a vat was less than 400 pounds. For experiments with 400 to 800 pounds of milk in a vat a pair of vats of 800 pounds capacity w r as used. These were stirred with a pair of w r ooden rakes, exactly alike in shape and size. Larger quantities of milk than 800 pounds were always handled in a vat of 2,400 pounds capacity in which a two-bladed rotating and oscillating agitator was used instead of the rake. The difference in yield between duplicate vats could not be traced to the methods of stirring. Thus, on March 27, the agitator-stirred vat (D) gave 0.83 per cent greater yield than the hand-stirred vat (C), but on April 10 the hand-stirred vat (D) gave 0.62 per cent greater yield than the agitator-stirred vat (C). The average difference on 12 days in yield between duplicate rake-stirred vats was 0.70 per cent, and the average difference in yield between duplicate hand-stirred vats on 19 days was 0.52 per cent. The differences varied slightly whatever method of stirring was employed. 60 ("ll l M>\l: till 1-1. I ROM PAS! EURIZED MII.K. ain, handling different amounts of milk did not appear to affect the yield in duplicate \ais. On L2 days, using one and one-half to three times as much milk in one \ r a1 as in the other, the average differ- ence in yield was 0.40 per cent, which is a little Bmaller than the average of the other days, showing thai the quantity of milk handled h\ this method does not affect the yield. Since the same results are obtained in a small \ai with .17.") pounds of milk as in a large one with 1,125 pounds of milk, it is believed that the general result^ of this investigation are applicable to the Largest sized vats of milk used m factories. BHRINKAOl BEFORE PARAFFINING, LND YIELD Ol PARAFFINED CHEESE. Since there is always some loss in weight of cheese previous to paraffining, it is of interest to compare the shrinkage of ordinary cheese with that of new -process cheese, and to determine whether there is an increased yield of pasteurized-milk cheese when paraffined Corresponding to the increased yield observed in the same c! when green. This can he done readily from Table 23, which shows the average results for the season and also the range of daily variation. Table 23. Comparison of old and new process che* hrinkagt be/on paraffining anil yii Id of paraffined < i ■ Shrinkage per loo pounds of green Yield per 100 A ge cheese hi' fore pounds of in (lain in when paraffining. yield made. jiar- alline«l. by new process. Pasteur- ized. Raw. Pasteur- ized. MM. Dat/s. Pounds. Pounds. Pound*. 1 '<>u nds. Per cent. Peb. 23 19 6. '.'2 5. 23 9.30 24 1^ 5.98 9.60 9. 14 27 15 4.67 9. Is < | i 28 14 7). 23 4. 7,7 '.' 74 9. 14 Mar. 1 13 4.ss 1*. 36 2 21 •j 12 6.26 4. 36 9. 49 4.44) ii 17) 6.71 «.»71 '.'. 4s 2. 4:< 7 11 4. ).i 111 - 10 1 s, 9 '.' 4.S2 9.35 3.53 10 ■A. 35 •'. 17 13 12 :,.us 4.2s 14 11 5. 13 4.26 10.26 9.50 us 10 3.96 ;i. 73 9. 7s 9.50 16 it 4. 22 3.61 16.25 10.04 17 B 3. 27 10.03 •-'(i 12 4.;<7 9. 1 1 :, 16 L'l 11 1 12 23 10 4.72 9. 19 Apr. 5 10 4. 36 9. 82 7 B 4. 10 8, 85 9.20 ) Ml 11 10 4.66 9.51 9. 14 4.06 a B 4.06 '.i. 1 1 2. i 3 17 12 6. 1 1 4.23 7 16 Is 11 1 v.", 4.42 9.40 8.81 21 12 6.06 4.11 9. M) 27 3. - 1 9. 32 28 B 1.72 Mr, 2 11 :<. 93 I 10 •1 us 9.31 «». 17 1.61 B 13 i 66 8.01 in U i I't :<. 73 9. 32 i:. 12 i 1 i 4.36 9.71 9. I'i 17 ID •*. 4<> '.I. I'i 22 12 4.71 in. us 7.7,7 28 11 4.71 9.74 u 4.72 4..!7 in. in 4.e.» COMPARISON OF S1IK1NK \i;K IJY OLD AND N E \\ PROCESSES. 01 Table 23. — Companion <>/ <>l shrinkage before paraffining ana yield of paraffined cheese Continued. Shrinkage pit kid pounds of green y [eld por 100 Ago oheese berore pounds of milk. 1 i;iiii in Date when paraffining. yield made. paraf- fined. by new Pasteur- ized. Raw. Pasteur- ized. Ra a 1911. Days. Pounds. Pounds. Pounds. I'tni mis. Per ci nt. June 1 10 3.92 3.67 10.05 HUH n. id 2 9 4.22 3.92 9.93 'i..., 3. 98 7 7 4.21 3. 66 9.66 9. 22 4.77 9 8 3.80 3.58 9.90 !i. 42 5.09 13 10 5.26 4.74 10.40 9.55 s. Ill) 15 8 4.49 3.82 10.18 9.70 4. it.", 16 7 4.43 3.64 9.97 9.51 4.84 19 12 4.85 4.27 10.29 9.53 7.97 21 10 4.46 4.18 9.78 9.31 5.05 26 12 4.53 4.17 10.00 9.40 6. 38 27 11 4.19 3.80 9.99 9.50 5.16 28 10 4.02 3.41 10.30 9.90 4.04 July 3 14 4.56 3.91 9.49 8.69 9.21 6 11 4.20 4.01 9.86 9.61 2. 60 8 9 3. 64 3.42 9.79 9.19 6. .53 10 10 4.80 4.64 9. 60 8.86 8. 35 11 11 4.46 4.01 9.77 9.26 5.51 12 10 4.54 3.6;": 10.19 9.42 8.17 Aug. 29 11 4.99 6.07 10.18 9.88 3.14 30 10 4.22 4.05 9.97 9.61 3.75 Sept. 1 8 4^14 4.14 10.15 9.77 3.89 5 13 4.35 4.05 10.17 9.74 4.42 6 12 3.82 3.49 10.09 9.54 5.65 7 11 3.49 2.99 10.45 9.98 4.71 8 10 3.17 2.81 10.45 10.07 3.77 20 10 3.80 3.41 10.66 10.21 4.41 22 8 3.43 3.21 10.64 10.19 4.42 25 Average.. 16 6.49 5.87 10.49 9.94 5.53 4.546 4.078 9.833 9.3S8 4.761 In practically every case in Table 23 the pasteurized-milk cheese showed a greater shrinkage than the raw-milk chees e during the period before paraffining, which was 7 to 19 days. The average shrinkage of raw-milk cheese before paraffining, for all 65 cases, was 4.08 pounds per hundred of green cheese, and for the pasteurized-milk cheese it was 4.55 pounds per hundred, nearly one-eighth greater than the raw. This excess shrinkage is observed whether the cheese was paraffined at 7 or 14 days, as is shown in the following table, which is a summary of Table 23. Table 24. — Shrinkage of cheese when paraffined at different ages (summary of Table 28). Average shrinkage in weight per 100 Age when paraffined. Cases av- eraged. pounds green cheese. Excess in pasteurized. Pasteur- ized. Raw. Per cent of Days. Number. Pounds. Pounds. Pounds. raw. 7 to 8 11 3. 9.5 3.56 0.39 11 9 5 4.31 3.88 .43 11 10 16 4.35 3.83 .52 13 11 12 4.52 4.10 .42 11 12 10 4.84 4.17 .67 16 13 to 19 11 5.29 4.78 .51 11 62 < II EDDAR I ll EESE 1 ROM PAS! EURIZED MILK. On account of this excess shrinkage before paraffining, amounting to about one-half |><»iinf cheese after paraffining was studied: (1) With cheese cured at Madison, Wis., .-it a temperature t<» 7"» : (2) with cheese cured al New Orleans, La., and weighed both at New Orleans 1 and Madison; (3 with cheese cured at New Orleans or at Columbus, Ga., and weighed both at Chicago and at Madison; I \> with cheese cured in a warm room at Madison; and (5) with cheese put in cold Btorage at :; 1 K. at Waterloo. Wis., at differ- ent ages after paraffining. So far a- possible duplicate cheeses from the same days' make were cured in the different ways stated. These different methods of curing were chosen for study as repre- senting (1) curing conditions at Wisconsin factories; (2), (3), and (!) condition. t«» which annually large amounts of cheese arc subjected when shipped south for sale; and (">) when cured in cold storage as Commonly practiced by dealer-. The shipments to New Orleans wore sent on four date- between April 29 and July 24, 1911. Each shipment consisted of 9 to 25 pasteurized-milk cheeses, and an equal Dumber of raw-milk eh' for comparison. In order that the cheese stored might he a- repre- sentative as possible, each pair represented a different day's make. l-'->r each lot of cheese shipped away from Madison for storage, a duplicate lot from the same days' make was kept at Madison. The method of designating these different l<>t> of cheese is Bhown in Table 25: Table 25. — Rej mh< rs to diffen >rf lots of cheese stored in l^n . Data made. CI . ■ Cured at Madison. Cured at New Or- leans. Ci:n'r- leans and Columbus, (la. Cured in warm room at Madison Cured at Moo, Feb. 23 i" Apr. if,.... Api 17 ,M:i\ 23 to June 16.. . . Jane 19 to July 12. ... July n i" Aug. 21.... ri to l'ii: 211 1 230 ' 248 to 263 ! \ u 3A ) \ ■ \ IB 2B 3B 415 3C 4C . 41) Tn addition to weighing each cheese separately they were also weighed in lots of five, and the close agreement of the weight of a lot details of the work at New Orleans connected with the storage, weighing, and shipping of the Mr. W '. J. Bleacher, junior dairyman of the Dairy Division, Bureau of Animal industry. Thanhs are duo to Mr. Blaaohar for his vary careful attention to this work. CUEING VARIOUS l.K N < i'l 1 1 S t>l I I M 63 of five with the sum of the five separate weights proved the accuracy of the weighing. This general method of double weighing was followed in obtaining all the weights of cheese in the I 1 lots. The tabulated results show the shrinkage of the different lots and the yield of green, paraffined, and cured cheese per hundred pounds of milk. In addition to tin 4 average results for each lot of cheese, the individual variations in shrinkage and yield of the single chei are shown, from which the extent of daily variations from the general average figures can be studied by anyone interested. Cheese cured at Madison (lots 1A to 5 A). — Fifty-two pairs of cheese cured at 60° to 70° w r ere weighed one or more times (92 times in all) at different ages, from 21 to 117 days after paraffining. In every case there was a gain in yield of pasteurized cheese over raw cheese. The gain averaged 4.59 per cent among 10 pairs of cheese cured 20 to 30 days, 4.58 per cent among 37 pairs of cheese cured 30 to 60 days, 4.38 per cent among 28 pairs of cheese cured 60 to 90 days, and 3.58 per cent among 17 pairs of cheese cured 90 to 117 days. On the average of all cases the gain in yield of pasteurized over raw was 4.22 per cent of the weight of the cheese. Table 26. — Comparison of yield of raw and pasfeurized-mtlk cheese after curing for various lengths of time at Madison, Wis. Weight of cured Time cheese per 100 Date made. cured alter pounds of milk. Gain by pasteur- ization. paraffin- ing. Pasteur- ized. Raw. 1911. Days. Pounds. Pounds. Pounds. Per cent. Apr. 24 21 9.27 8.96 0.31 3.46 Mar. 20 26 9.52 9.06 .46 5.08 21 26 9.40 8.94 .46 5.15 22 26 9.37 9.12 .25 2.74 20 33 9.47 8.99 .48 5.34 17 32 9.87 9.63 .24 2.49 16 32 10.02 9.96 .06 .60 15 32 9.68 9.38 .30 3.20 14 32 10.03 9.34 .69 7.38 13 32 9.72 8.80 .92 10.46 2 42 9.53 9.36 .17 1.81 7 42 9.57 9.49 .08 .84 8 42 9.61 9.51 .10 1.05 9 42 9.55 9.29 .26 2.80 10 42 9.62 9.09 .53 5.83 Apr. 17 42 9.30 8.73 .57 6.54 18 42 9.13 8.64 .49 5.67 May 15 44 9.43 8.89 .54 6.07 17 44 9.15 8.85 .30 3.39 June 13 44 9.86 8.94 .92 10.29 15 44 9.70 9.30 .40 4.30 16 44 9.64 9.04 .60 6.64 Feb. 23 45 9.12 8.63 .49 5.67 24 45 9.26 8.93 .33 3.69 27 45 9.51 9.00 .51 5.67 28 45 9.49 8.99 .50 5.56 Mar. 1 45 9.57 9.08 .49 5.39 2 45 9.21 8.94 .27 3.02 Apr. 11 50 9.29 8.98 .31 3.45 13 50 9.06 8.86 .20 2.26 May 10 50 8.95 8.51 .44 5.17 June 7 50 9.19 8.79 .40 4.55 9 50 9.41 8.58 .83 9.67 64 CHEDDAR CHEESE FROM PASTEURIZED MII.K. Tabu 26.— H td-milk cfo canny fur 1 otinued. Time cured pounds of milk. by . -n. • ■ 191 1. I'i r a nt. Jul. 51 61 .14 - JllIU' 1 • .10 1.06 Mi \: km Ma 58 3 .if, 1.84 Apr. 7 .47 62 9.40 v 71 ft] 9.16 . 17 28 • -1 19 21 0. If, .44 ATM 65 .15 1.70 65 8.10 .68 24 9.01 . 33 Mar. 10 'X 10 24 21 «.'. 1.') . 18 20 9.15 B.74 .41 Apr. 17 is 72 8.81 .47 Mar. 17 74 '.i. 4.: .1.") lf> 74 .17 1.7s 1.5 74 3.09 14 74 7.01 14 74 - " .84 Apr. 13 .is 11 VI) .V74 .24 7 .41 4.72 5 .4.-> ' ' Mar. 9 B4 8 84 9. 40 9.09 .:,1 3.41 7 B4 9.13 . 26 •J. V, 3 84 9.24 2.44 - 87 1 -7 .12 Feb 28 w 9.25 v71 27 S7 B.78 ^7 . - 3 Mar. 20 - 3.71 21 - V44 .:.i 6.04 22 8.91 17 104 .12 16 104 9.61 .if. 1.71 15 104 9 12 14 104 '.'.41 13 104 '.'.14 • - 114 3.44 8 114 0. 1 4 V XV - ! 7 ' 114 9.14 .21 3 114 9.06 .21 2 117 S - 8.51 .29 :;.4l 1 117 .11 1.2S Feb. 28 117 9. l.' - .40 117 o. 16 .46 24 117 .17 1 "7 Avt ■ 8.907 .38 4.22 Cl<<ts IB to J[B). Fifty-four days 1 make represented by •"> l raw mid 54 pasteurized-milk cheeses were shipped to New Orleans in four lots at different times during the n. Tli. ihowed an increased yield for. the new-process cheese compared with the old. in every case. The average figures f<»r each l<>t are given in Table 27, CUBING VARIOUS LENGTHS OB 1 TIME. 05 Table 27. — Average yield per 100 pound* of milk of raw and pasteurized-milk cured a! YU. Method. Num- ber of days' make. Yield of cheese per 100 pounds of milk. Lot Green. Paraf- fined. Ship- ped to New Or- leans. Re- al New Or- leans. Stored one month. two months. Re- ceived at Madi- son. f Pasteurized 25 25 Pounds. 11). lvi 9. 67 Pounds. 9.26 Pounds. 9.55 9.16 Pounds. 9.52 9.14 Pounds. 8.36 Pounds. 7.85 Pounds. 8.31 Haw 7.78 IB Gain, pounds .52 5.37 .43 4.64 .39 4.25 . 38 4.16 .49 5.86 .53 6.75 .53 Gain, per cent 6.81 9 9 9. S3 9.45 9.40 9.08 9.37 9.05 9.26 8.97 8.48 8.12 8.40 Raw 8.01 2B Gain, pounds .38 4 02 .32 3.52 .32 3.54 .29 3.23 .36 4.43 .39 4.87 f Pasteurized 10 10 10.47 9.93 9.99 9.54 9.92 9.47 9.77 9.34 9.29 1 8.69 9.17 Raw 8.55 3B Gain, pounds .54 5.44 .45 4.72 .45 4.75 .43 4.60 .60 0.90 .62 Gain, per cent 7.25 f Pasteurized 10 10 10. 38 9.G9 9.92 9.31 9.83 9.24 9.78 9.19 8.94 : 8.71 Raw 8.28 8.14 4B Gain, pounds .69 7.12 .61 6.55 .59 6.38 .59 6.42 .66 7.97 .57 Gain, per cent 7.00 (Pasteurized 54 54 10. 22 9.68 9.74 9.29 9.64 9.21 9.57 9. 16 8.89 8.37 8.56 Raw 8.03 1-4 B Gain, pounds .54 5.58 .45 4.84 .43 4.r Btorage in the South through a firm 1 ofchi lera in Chicago, who weighed the cheese, both before and after Btorage for one month. In the first shipment l cheese, No. 243 - Lost in transit, and iji the second shipment, 2 ch< 254 1 and 254C1, were damaged so thai their weights arc not included in the following summary. Jn the first shipment, according to the Chicago weights, 9 pasteurized-milk cheeses weighed 172J pounds before and 162] pounds afterwards. The loss, 10J pounds, is 5.94 percent of the original weight. In the dpment K) raw-milk ch( weighed 189J pounds before shipment and 175 pounds afterwards. The Loss here. 14J pounds, is 7.53 per rent of the original weight. Jii the second shipment nine pasteurized-milk i 176* pounds before and 1593 pounds after pounds, is 9.49 per cent of the original weight <>f the cheese, in the same shipment nine raw-milk cheeses weighed 161 pounds before and pounds after storage. The loss in this case, L6J pounds, is 10.09 | er cent of the original weight. In both shipments the raw- milk cheese lost a greater per cent of their w eight than the pasteurized- milk cheese. On comparing the individual - in pairs, it was found that in most cases the pasteurized-milk cheese 1 Bt Less than the raw-milk cheese, although hi a few true. The weights taken at Madison on the saim e the figures shown in Table 28, agreeing substantially with the results obtained at Chicago: Table 2S.—Ai i ith. Method. i of milk. - 1 ! ■ . . 3 \ .."■4 .46 10.38 .69 .61 ,60 7.10 In this work. CHEESE CURED IN WARM ROOM. 67 Cheese cured in a warm room (lots 3D and 4D). — To Further test the effect of storage at high temperature 40 cheeses, lots 3D and -H). were put for 47 days into a warm curing room at Madison where the temperature was held at 75° to 85°. TABLt; 29. — Average yield per hundred pounds of milk of run- and pasteurized mill; cheese cured in warm room. Method. Number m.ike. ' 100 pounds of milk. Lot No. Green. Paraf- fined. Put in Tata? room. ™™ room. 9 Pounds. Ki.47 9. 93 Pounds. 9.99 Pounds. Pounds. 9.91 , 9.37 9.46 ' 3D . 7.4 .45 4.72 .45 4.75 .49 5.52 9 9.92 1 9.33 9.31 | 8.73 4D til .62 G.72 60 7.12 From these results with eight lots of cheese— IB, 2B, 3B, 4B, 3C, 4C ', 3D, and 4D — it can be stated with certainty that pasteurized-milk cheese does not lose more in weight than raw-milk cheese when stored in warm rooms or in the South, after paraffining. On the contrary, the pasteurized-milk cheese lost on the average a smaller percentage of weight in warm storage than the raw-milk cheese. At first this fact seemed inexplicable, but the reason became clearly apparent from inspection of the cheese kept in the warm curing room at Madison. Within a few days after going into the warm room the raw-milk cheese became very greasy on the surface, and the grease running on to the shelves and the floor marked the spot where each cheese stood. The pasteurized-milk cheese, standing alongside of them on the same shelves, did not exude grease, or only very slightly in a few cases, and the difference between the greasy raw-milk cheese and the dry surface of the pasteurized-milk cheese was so marked that there was no culty in picking out each kind by the sense of touch alone. To demonstrate further the difference in this respect, each cheese of the last lot when put into the warm room was placed on a piece of wire gauze in a shallow tin pan, so that the grease running from each cheese could be collected. A very little of the paraffin was scraped from the surface of each cheese by contact with the wire gauze in the bottom of the pan. The total weight of material, practically all paraffin, collected from the 10 pasteurized-milk cheeses weighed 0.13 of a pound, while the material, mostly fat, with a little paraffin and mold, collected from the raw-milk cheeses, weighed 1.92 pounds, vmich is 1.2 per cent of the'weight of the raw cheese when placed in the store- room. 68 CHEDDAR RIZED MILK. At present we are unable to explain \\ ith certainty why the past ized-milk cheese should losefaf Less readily when stored al 7n c t< than the raw-milk cl Further Btudy will be made of this phe- nomenon. The purpose <»f beginning these Btudiee of losses of weight in warm rooms waa to determine whether the increased yield obtained by pasteurization would be offset by increased I weight when pasteurized-milk cheese arc Bhipped to the South, and it i- now fully demonstrated thai the pasteurized-milk cheese stored in the South maintain their advantage as to increased yield. Cheese placed in cold storage at Waterloo, R "/•.'. Thel of weight observed in 35 pasteurized-milk cheeses put into cold Btora •' at different ages are Bhown in Table 30. T. represent Beven days' make during July and August, 1911. Table 30. — shrinkage of pasteurized-milk d < I storage. When parutlined. When put When made. Weight, green. into cold stoi out of cold : 'ge. Totul shrinkage. Age. Weight. Age. Weight. Age. Weight. 1911. Pounds. Day*. Pounds. Days. Pounds. Pounds. Pounds. Per cent. Julv 19 9 (») P) 18.15 11.89 10 21.11 1 1 100 .73 19 20. 10 : 19. 21 7 19. 21 100 19.15 19 264-1 21.07 9 14 100 1.22 19 19. S9 9 28 18.70 100 1.61 19 9 19.44 41 10* J 21 22.49 8 (») w 99 21 1 17.58 17.45 .53 21 7 7 19.35 99 21 18.86 8 17.98 14 99 17.::, 1.11 21 B 18.68 28 18.42 99 1.53 7.81 21 19.25 18.40 18.13 99 1.57 21 19.75 8 18.86 40 99 18.10 25 1 287-1 - 32 11 19.86 (") (") 95 - - 11.14 20.29 1 19.95 1 19. 95 95 2.41 19.97 7 19.11 7 19.11 95 1.07 5.35 11 14 - 95 - 3 1.17 5.43 25 . S 11 29 95 18.58 8.15 22 - 11 43 . - 95 1.95 18.70 9 17.80 (>) (») 93 16.45 - . 27 1 19.45 93 19.20 3.42 27 19.83 7 19.01 7 19.01 93 .90 9 14 19.92 93 19.55 27 18.80 9 17.91 27 17.00 93 27 20.22 9 41 93 l.'.C Aug. 1 21.91 11 (*) (») 19.00 2. n 13.28 1 272 2 19.78 1 1 19.30 19.05 .73 3.09 1 19.40 7 7 18.55 1.18 6.08 1 21.82 11 20.55 14 20.55 7.19 l 21.80 11 29 19.90 1.90 1 21.75 11 40 19. 75 89 19.50 10.34 1 19.90 11 w (») 13.56 8 276-2 1 1 81 4.01 8 2il. A4 7 7 M 1.14 5.57 8 19.90 11 15 1.56 7.53 8 19.70 11 18.45 28 is. 21 17.75 1 . 96 20. In 19.90 ( J ) 1 19.50 18.10 19. 3S 2. (HI 9.95 r 19.68 8 18.81 8 18.81 18.76 .93 4.72 ii 15 17.70 17.40 1.40 7.44 19.84 ii 18.84 67 IV 4.'. 7.00 ii 17.62 42 (■) >l MM AMY. i 7 day. ireek. 7 2 weeks. 4 we 7 eks. 6 w 6 eeks. 1 7 n cellar. 1 hoi . A \- shriii- per 5.10 C. 51 8.29 9.29 11.78 » In warehouse at Waterloo, Wks., by courtesy of the Ko.icu A Seeber Co. 1 Cured in cellar. CAUSES OF INCREASED HELD. 69 Although the seven cheeses put into storage at the age of l day showed an average oi' only 3.22 per cent shrinkage after three months, yet they wore not well broken down and required further curing at 60° to 70° to get rid of their curdy, lumpy texture. The cheese paraffined and stored when 1 week old showed an average total shrinkage of 5.10 per cent, and these were found to be thoroughly broken dow r n when taken out of cold storage. This series appears to indicate that the quality of pasteurized-milk cheese is not damaged by placing in cold storage at the age of 1 week, while the shrinkage (5.10 per cent) is about half that of the duplicate cheese, cured in the cellar at Madison (11.78 per cent), as shown at the bottom of the table. THE CAUSES OF THE INCREASED YIELD FROM PASTEURIZED MILK. THE LOSSES OF FAT FROM VAT AND PRESS. The increased yield of green cheese from pasteurized milk, amount- ing to over 5 per cent (Table 20), is due partly to the fact that about half of the fat lost in the whey and drippings by the old process is retained in the cheese by the new process of making. Also it is found that a little more moisture can safely be incorporated in the new-process cheese without danger of spoiling it, but on the contrary giving it a moist, fat appearance which consumers generally like. The loss of fat in the whey is caused partly by the passage of the curd knives through the curd in cutting, at which time a considerable proportion of fat is brushed away from the surface of the curd cubes. During the stirring and heating some further fat globules are lost from the curd cubes, and still further losses occur after milling and during pressing. In the new process of making cheese from pasteur- ized milk the. curd is so firm and elastic (not brittle) at the time of cutting that the loss of fat in the whey averages only about one-half that observed in cheese making by the ordinary process. The average fat content of whey from good clean milk is stated to be 0.30 per cent and from average cheese factory milk 0.36 per cent. 1 On a great many days during the past two and one-half years the milk supply in the receiving vat has been divided and one half made up by the regular methods and the other half by the new method. The quality and composition of the milk was thus the same in both vats. On the 24 days listed in Table 31 the average fat content of the whey from the regular vats was 0.25 per cent and from the pasteurized-milk vats was 0.159 per cent. » Van Slyke and Publow, loc. cit., pp. 189, 190. L CHEDDAB CHEESE FBOM PASTEUBIZED MILK. TABU 81. <>n of the percentage of fat in « I and by regular nutl • making. milk. ' of milk drawn. whey drawn. 1911. . ; I l'er cent. 4 1 M 17 .14 t 1 .15 .') "*4.*6" .17 7 4.1 . 18 8 .Ki 1909. July n .15 .21 .12 4.0 .15 to .12 12 3.7 .18 - July LS 4.1 2t>0 .12 Oct. l 4.7 2 4 5 200 .18 7 4.4 .14 .19 8 4.0 .15 Sept. 1 4.3 .17 2 4.2 .is 14 12 . is .24 16 4.(1 .27 17 4.4 .19 L8 4.4 .is 19 4.2 .17 1 .150 .25 Tn those cases the small amount of milk handled in each vat per- mitted hand stirring, and neither the rake nor the agitator \\ By this means the whey fat of the regular-process vats was kept at a lower figure, perhaps, than could have been done with large vats, as handled in a commercial factory using the regular proc< On 22 days, using l.'Joo to 2,000 pounds of pasteurized milk in each vat, the percentage of fat in the whey at the time of drawing the whey averaged 0.17 per cent, as shown in the following table. In the - the vats were stirred with an agitator. Table 32. — Fat content of whey j teat. Fat in whey two if tor cue :ht Of milk bandied. of cl .' L910. Jui.' Per cent. 0.14 . Ki .17 .12 .18 .14 .18 .17 Pound*. 1 . 427 1.431 Pounds. 144 166 147 CAUSES OF INCREASED HELD. 71 Table 32. — Fui content of whey from pr the determination of yield and shrinkage. The samples of cheese weighed into the Babcock bottles were rapidly dissolved in a mixture of hot water and >ul- phuric acid, b d by one of us in a previous paper. 1 / milk Data. ' lied. Raw. DIflei 1911. Feb. 24 27 28 .Mar. 1 _> 3 7 B 10 13 14 15 16 17 21 22 Apr. 5 11 13 17 is 24 Max 2 - in 15 17 A\ • 31.60 31.05 31.90 32. r. 33. 15 31.62 34. 15 32. 90 34. 10 31.78 32. 28 34. 17 31.02 31.87 P(TCt. 30. 15 30.75 31.47 30. 17 31.45 30.00 31.95 30. >7 30. in 32. 20 3t.97 30. 15 32.70 3.40 .85 I', ret. + l'(TCt. 2. 15 1 . 15 1.00 3. 15 .17 .04 1. It 5 1.85 1.61 1.92 41.43 .1^ 1.13 1. 15 .15 1.82 1 . _'n .01 .71 32. 09 .01 38.59 .05 .26 The combined effect upon the percentage composition of ch< caused by increasing both the fat and moisture content is Bhown in the following example: Ten pounds of raw-milk cheese of the same average percentage composition as in Table shown at 1. below, would contain the weights of fat, moisture, and casein, etc.. shown at II. if by pas- teurization the fat. content of the cheese is increased ahout 1 per cent of itself, ami the moisture content i^ increased ahout li'^ per cenl of itself, there will he ohtained L0.54 pounds of pasteurized-milk el . '.est. Journal of Industrial aiid - • . lag., utw. QUALITY OF PASTEURIZED-MILK CHEESE. 7.") as shown at III instead of 10 pounds of raw-milk cheese, a theoretical gain of 5.4 per cent in the yield of cheese. (The actual gain shown in Table 20 was 5.37 per cent.) The percentage composition of this pasteurized cheese will be as shown at IV, which agrees closely with the average composition of the pasteurized-milk cheese .shown a1 the bottom of Table 38. I. II. III. IV. Far 3S.V) per cent, 3.859 pounds+0.154 pounds=4.013 pounds. 38.07 per cent- Moisture.. 31.28 per cent. 3.128 pounds+0. 391 pounds=3. 519 pounds. :;:;.:;: percent, i. etc. 30.13 per cent. 3.013 pounds+. --- pounds=3. 013 pounds. 28.57 per cent. 100.00 per cent. 10.000 pounds. 10.545 pounds. 100.00 per cent. The increased moisture content of pasteurized-milk cheese made by this process is due to the effect of pasteurization on the properties of curd, as stated on page 25. THE QUALITY OF PASTEURIZED-MILK CHEESE. SCORES AND CRITICISMS OF PASTEURIZED AND RAW MILK CHEESE. The milk supply used at Madison is no better than the average cheese-factory milk. Sunday's milk is delivered on Monday through- out the year and is therefore inferior to that of the other days. Cheese from every day's make during the season was scored by two judges, Mr. U. S. Baer, assistant dairy and food commissioner of the State of Wisconsin, and Mr. A. T. Bruhn, junior dairyman, United States Department of Agriculture, who during the past year have scored the cheese sent to the monthly scoring exhibition, conducted by the Wisconsin Experiment Station. The judges worked independently and pinned their scoresheets to each cheese without knowing even the numbers of the cheese, which were turned toward the wall. Their scores show close agreement with each other in most cases and leave no doubt as to the relative quality of the cheese scored. After finishing about 20 of the cheeses, they turned them around and added the cheese numbers to the sheets. In general, a score of 92 or above indicates that the cheese is of good quality and salable at full market price. A cheese scored below 92 is likely to be cut in price in a dull market. Tables 39 to 46 show the scores of both judges as well as the average scores, which latter are used in the discussion. Raw-milk cheese is in all cases indicated by the letter C attached to the serial number. CHEESE CURED AT MADISON AT NORMAL TEMPERATURE. Lots lAj 2 A, 3 A, and J+A. — These lots include 53 pairs of cheese cured in the cellar at Madison. The temperature of the curing room showed daily about 3° to 5° difference between maximum and mini- mum and ranged from 60° to 73° from February to July, 1911. By opening the windows at night only, it was kept at 60° to 70° from July to October. 76 CITEDDA1 5E i ROM PAS! EURIZED MILK. r Ili< of the 53 pairs of chi as shown in Table 39. The re of all the pasteurized-milk < i] ■ • _* . 7 r> and of the raw-milk cheese v.' >"sc (lots 1 '/ lit M LA AM* 2A, 91 OBED Jl l.v 17, 1*1 1 - 'lVm- BruhiL curing room B a. in. vor. Hire. To'ul. lore. Total. ture. •F. 1911. Feb. 24 172 41.0 92.0 40.0 91.5 40.50 24 172C 27.0 27 42.5 28.0 27 40.0 27.0 92.0 27.00 91.00 174 41.0 41.0 41.00 174C 90.0 Mar. 1 17:. 41.(1 27.0 40.0 20. 91.0 92.00 1 175C 40.0 91. 40.0 1 178 40.0 93.0 41.0 93.0 40.50 93.00 9 176C 37.0 27.0 39.0 27.0 91.0 27.00 90.00 3 177 40.0 92.0 40.0 91.5 91.75 3 177C 26.00 : 178 40.0 91.0 40.0 27.0 40.00 91.50 7 178C 27.0 90.0 " 91.0 27.00 90.50 8 179 92.0 41.0 8 179C 35.0 26.0 - 180 41.0 20. 92.0 41.0 27.0 93.0 41.00 92.50 9 39.0 26. 90.0 40.5 92.0 91.00 10 181 41.0 26. 92.0 42.0 27.0 41.50 93.00 Id 181C 27.0 39.0 90.25 13 182 40.0 41.0 27.00 92.50 13 182C 41.0 92.0 40.0 14 183 40.0 91.0 40.0 40.00 91.25 14 40.0 92.0 40.0 91.5 40.00 15 184 40.0 26. 91.0 41.0 27.0 40.50 15 184C 40.0 92.0 41.5 27.0 " go" 16 185 40.0 41. 5 10 l?5C 20. 41.0 27.0 17 186 42.0 28.0 41.0 41.50 17 !8fC 41.0 94.0 41 (i 27.0 93.0 41.00 03" 20 187 43.0 27.0 95.0 41.0 20 187C 35.0 25.0 39.0 ■ 37.00 21 188 43.0 •_n.ii 96.0 41.0 93. 21 188C 38.0 40 27.0 39.00 '"go* 22 189 43.0 27.0 95.0 95.00 22 189C 39.0 27.0 91.0 39.50 "'& Apr. 5 198 43.0 27.0 42.0 5 198C 41.0 27.0 93.0 41.5 7 42.0 •J7.ii (14.0 42. "4.0 "'ei' 7 200C 35.0 40.0 ! 91.0 11 202 42.0 20. 93.0 27.0 11 202C 26. 90.0 27.0 39.50 91.00 13 •_>, .4 41.0 27.0 93.0 42.0 - 41.50 94.00 39.0 20. 90.0 4O.0 27.0 39.50 91 00 17 41.0 93.0 41.0 27.0 93.0 41.00 93.00 17 206C 40.0 90.0 38.0 25.0 S7.0 39.00 18 43.0 20.0 94.0 41.5 27.0 18 42.0 92.0 40.0 90.0 41.1X1 9] 00 24 211 43.0 26.0 94.0 42.0 27.0 211C 2.-..0 ftg (i 39.0 27. 91.0 39.00 90.00 •_>7 214 40.0 42. 5 27. 27 214C 37.0 24.0 - 37. 37.00 R7.00 28 215 42.0 94 42.0 27.0 42.00 27.00 94 00 37.0 B7.0 a 211 41.0 26. 92.0 40.5 "l 6 •1 78 ■ 2 21 C 37.0 \i:>.o S7.0 n vv 00 3 217 42. 95.0 41.5 27.0 41 77. 3 217C 37.0 ^7.0 40.0 26. 91.0 B 220 41.0 27. 93.0 42.0 27. 94.0 41.50 27.00 ^ 25 «4.0 25.0 36. 50 in 40.0 25.0 90.0 40.0 27.0 40.00 "1.00 10 2224 J 37.0 - 40.0 91.0 - • R9. 00 15 225 40 24 Q "1 (i 4 2.0 41 00 27.00 93.00 '"&' 15 vi n 27.0 r M.O 17 41.0 '.'2. 41 .0 27.0 41.00 17 35.0 24.0 B4.0 37.0 25.0 36.00 S5.50 "C" In this column indicates raw-milk cheese. QUALITY OF PAST I : I ' HI/. KM MILK CHEESE. 77 Table 39. — Scores of 58 pairs of raw and pasteurized cheese (lots 1 A l I and LI) cured at Madison Cum Lnued. LOT 3a, scored AUGUST 14, 1911. Tem- pera- ture of Date Cheese Scored by U.S. Baer. Scored by A.T. Bruhn. curing room s a. in. made. No. 1 Fla- vor. Tex- ture. Total. Flavor. Tex- ture. Total. Flavor. Tex- ture. Total. •F. 1911. 67 May 22 230 43.0 27.0 95.0 41.5 26.5 93.0 42. 25 26. 75 94.00 ' 22 230C 40.0 26.0 91.0 37.0 25.0 S7.0 38.50 25.50 SO. 00 66 25 233 41.0 25.0 91.0 41.0 26. 92. 41.00 25.50 91.50 25 233C 38.0 25.0 88.0 36. 25.0 86.0 37.00 25.00 S7.00 29 234 42.0 27.0 94.0 42.0 27.0 94.0 42.00 27.00 94.00 • 29 234C 39.0 25.0 89.0 37.0 25.0 87.0 38. 00 25.00 88. 00 June 1 237 42.0 27.0 94.0 41.0 26. 5 92.5 41.50 26. 75 93.25 6G 1 237C 35.0 25.0 85.0 38.0 26. 89.0 36.50 25.00 87.00 2 23S 40.0 26.0 91.0 41.0 26.5 92.5 40.50 26.25 91.75 66 2 238C 37.0 26.0 8S.0 37.0 25.5 S7.5 37.00 25.75 87.75 7 240 40.0 27.0 92.0 41.0 26.0 92.0 40.50 26. 50 92.00 66 7 240C 33.0 25.0 83.0 37.0 26. 88.0 35. 00 25.50 85.50 9 242 39.0 27.0 91.0 41.5 26.0 92.5 40.25 26. 50 91 . 75 70 9 242C 39.0 26.0 90.0 38.0 26. 89.0 38.50 26. 00 89. 50 13 243 40.0 27.0 92.0 41.0 26.0 92.0 40.50 26.50 92. 00 68 13 243C 38.0 25.0 88.0 38.0 25.0 88.0 38.00 25. 00 88.00 15 245 41.0 27.0 93.0 41.5 27.0 93.5 41.25 27. 00 93.25 66 15 245C 37.0 26.0 88.0 40.0 26.0 91.0 23. 50 26. 00 89.50 16 246 40.0 27.0 92.0 40.0 26.0 91.0 40.00 26.50 91.50 66 16 246C 40.0 26.0 91.0 39.0 27.0 91.0 39.50 26.50 91.00 LOT 4A, SCORED SEPTEMBER 18, 1911. June 19 19 21 21 26 26 27 27 July 248 248C 250 250C 253 253C 254 2540 255 255C 258 258C 260 260C 261 261C 212 262C 2C 3 263C 42.0 40.5 40.0 37.0 37.0 35.0 41.0 3/.0 41.0 35.0 40.0 35.0 41.0 37.0 40.0 38.0 41.0 37.0 40.0 35.0 27.0 26.0 26.0 25.0 25.0 25.0 27.0 26.0 27.0 25.0 27.0 25.0 27.0 25.0 25.0 27.0 27.0 26.0 26.0 26.0 94.0 91.5 91.0 87.0 87.0 85.0 93.0 88.0 93.0 85.0 92.0 85.0 93.0 87.0 90.0 90.0 93.0 88.0 91.0 86.0 42.0 40.0 41.0 38.0 39.0 35.0 41.0 37.0 41.0 37.0 40.5 35.0 41.0 36.0 39.5 38.0 41.0 37.0 40.0 35.0 27.0 20.5 26.5 25.0 25.0 26.0 27.0 26. 27.0 25.5 26.5 25.0 26.5 25.0 26.0 27.0 26.5 25.5 26.0 26.0 94.0 91.5 92.5 88.0 89.0 86.0 93.0 88.0 93.0 87.5 92.0 85.0 92.5 86.0 90.5 90.0 92.5 87.5 91.0 86.0 42.00 40.25 40.50 37.50 38.00 35. 00 41.00 37.00 41.00 36.00 40. 25 35.00 41.00 30.50 39. 75 38.00 41.00 37.00 40.00 35.00 27.00 26. 25 26. 25 25. 00 25. 00 25.50 27.00 26. 00 27.00 25.25 26. 75 25.00 26.75 25.00 25.50 27.00 26. 75 25.75 26.00 26.00 94.00 91.50 91.75 87.50 88.00 85.50 93.00 88.00 93.00 86. 25 92.00 85.00 92.75 86. 50 90. 25 90. 00 92.75 87.75 91.00 86.00 "C" in this column indicates raw-milk cheese. In 51 cases out of the 53 in the table the pasteurized-milk cheese received a higher average total score than the raw-milk cheese; but in two cases the raw-milk cheese scored one-fourth to one- half a point higher (Nos. 183 and 184). In the 51 cases just mentioned the differences in total score between pasteurized and raw milk cheese ranged from one-fourth of a point to 7 points and averaged 3.82 points. In four-fifths of these cases the difference in the score was over 2 points. In 49 of the 53 raw-milk cheeses the average score was below 92, while 39 of the 53 pasteurized-milk cheeses scored 92 or above. The distribution of the scores in each case is most clearly shown in figure 3. 78 CHEDDAR CHEESE FROM PASTEURIZED MILK. It can readily be seen From figure 3 that hi per cent (60 out oi of the pasteurized cheese scores lie between '.'l and 95, a range of i points, while the same proportion (9 i per cent of the raw-milk cl scores are quite uniformly distributed between 85 and 92, a ran 7 points. The variation in quality of product from day to v P/4STEU&/ZEQ-M/LK' CHEESE :: : : ••• •••• •• • ••••§••••••• • RAW-M/LK CHEESE i ... : . : .:: : : :•• . . ... ....... ... 85 86 87 39 90 91 92 93 TOTAL 3-CO/PFS. 94 95 96 Fig. 3.— Distribution of total scores of pasteurized and yaw milk cheese. t he new process. In scoring all o cheeses t tie color and make-up were al- ways marked per- fect . and the ch< were marked off only on flavor and texture. It is of in- terest therefore to consider the flavor and texture scores separately, in addition to the discussion of total -iveii abo The average flavor score for all of the pasteurized cheese Is 41.05 and for the raw-milk cl, $.13. In 50 cases out of 53 the pas- teurized-milk cheese lias a higher average l ! ore than the raw, in 2 cases the scores are equal, and in 1 case the uized cheese is one-fourth point less than the raw. In the 50 cases just mentioned the difference in the fla- vor score between the two makes of cheese ranged from 0.50 to 5.50 points, averaging 3.1 points. The difference was equal to or greater than. L.25 points in 47 out of the 50 -. showing that the improvement in flavor through pas- teurization was not only unquestionable, but also consistent. In 51 out of the the pasteurized-milk ch< ) or above for flavor, while 45 out of the 53 raw-milk che< ed below 40 Tor flavor. Figure 1 shows that 94 per cent (50 out of 53) of the pasteurized cheese flavor scores lie between 40 and 42J, a range of 2\ points: while the raw-milk cheese flavor scores are quite evenly distributed P/tSTEOR/ZeO-M/l/f CN££5£- M • • • i ••••••• ••• •••••••••••• • • &A W-M/LK CHEESE • • f • • * • • • •••••••• • 36 37 38 39 40 4/ 42 43 Distribution of flavor scores of pa iw milk PASrEUR/ZED -M/Uf CHEESE* • Li . : Hilh • RAW-M/LK CHEESE • • • i i • • • • i • : % : : • • # • • o c • •So • : 2* 25 26 27 23 CIIKKSK ( rilKD IN iiir. SOUTH. 79 aver a range of 5 points (from :;"> to 40 or 11 >. The range of varia- tion is thus twice as great in the raw as it is in the pasteurized, show- ing thai the daily variation of flavor is reduced about one-half by the new process. The average texture scores show also some advantage for the new- process cheese. The average texture score on all of the pasteurized- milk cheese was 26.70, and on the raw-milk cheese 25.96. In 40 cases out of 53 the pasteurized cheese scored higher than the raw, in live cases the scores were 4 equal, and in 8 cases the pasteurized cheese scored 0.25 to 1.5 points (average 0.59 point) lower than the raw. Among the 40 cases just mentioned, the differences in texture score between the two makes ranged from 0.25 to 2 points, and averaged 1.09 points. Figure 5 shows that 90 per cent (48 out of 53) of the pasteurized- milk cheese texture scores lie between 26 and 27.50 ; a range of 1.50 points; while 94 per cent (50 out of 53) of the raw-milk cheese scores are quite evenly distributed between 25 and 27, a range of 2 points, a distinct advantage in favor of the new process, both as to quality and uniformity of texture. CHEESE CURED IN THE SOUTH. Lot IB. — Four lots of cheese, lots IB, 2B, 3B, and 4B, were shipped to Xew Orleans for storage, the first lot for two months and the other three for one month. Lot IB consisted of 25 pairs of cheese which were made on 25 days between February 23 and April 18, at Madison, and shipped to Xew Orleans April 29, arriving May 9. They were stored there until July 3, and then shipped back to Madison where they were scored sepa- rately on July 17, 1911, by Messrs. U. S. Baer and A. T. Bruhn. The temperatures at Xew Orleans given below are taken from the United States Weather Bureau monthly meteorological summaries. The average daily mean for May was 75.8°, with temperature on different days varying from 60 to 96. For June the average daily mean was 83.2°, with temperature on different days varying from 70 to 98. The quality of both the raw and pasteurized cheese after returning from Xew Orleans was very poor, as shown by the scores of the judges and by letters from dealers to whom they were afterwards sold at a FIG. 5.— Distribution of texture scores of pasteurized and raw milk cheese. 80 CHEDDAB CHEESE FROM PASTEURIZED MILK. reduced price. The >re of the 25 pasteurized-milk ch< 35.10 and of the 25 raw-milk < . a difference of 1.76 points. In 17 cases out of 25 the pasteurized-milk chees higher, b [ual to, and in 5 cases Less than the raw-milk chees* Table 40.) The highest avei ire given to any cheese in the lot wi and the lowest 78.50. The scores are Bhown in Table 40. arj of rati * tuu ■ Date ma le. Bruhn). 191L 171 81 171C ^7 ^7 -7 172 -1 24 172C • 28 174 - 28 17IC 84 Mar. 1 175 " 1 175C - 84 2 L76 - 88 87 2 176C 3 177 84 3 177C 7 3 - - 7 - 8 179 01 8 179C S 84 9 180 ^7 9 I80C 33 85 10 181 88 10 181C - 85 13 182 S 80 3 13 § 80 14 S 14 15 35 15 85 32 16 B5 18 3S 85 ss 17 5 17 B 8 20 79 S 30 187C 21 77 21 80 - 189 - s 189C - 80 V ' • " 5 198C 81 7 - ^7 7 200C 32 11 M 89 11 - 13 2M 13 84 17 i 17 - 207 Jf 18 8 » "C" in this column indicates raw- CHEESE CURED IX THE BOUTH. 81 It can be soon that storage for so long a period as two months in New Orleans, at such temperatures, can not be practiced with either raw or pasteurized cheese without great loss of quality; and that of the two lots, the pasteurized was somewhat the better when taken out of storage. On account of the unmarketable quality of both Lots of cheese when scored it appears unnecessary to give the detailed score and criticisms as to flavor and texture. Lots 2B, SB, and 4B. — These lots were stored at New Orleans for one month each during parts of June, July, August, and September, 1911. The mean daily temperature during this period averaged 83.2° for June, 80.2° for July, 81.8° for August, and 82.6° for September. In lot 2B the 9 pasteurized-milk cheeses received an average total score of 90.44, and the raw-milk cheese of 85.56. The pasteurized was better in every case, and on the average 4.88 points better. PASrEUP/ZED-M/Ltf CHEESE \ \ • • • • • •••••• • • • •••••§•• •• •••• •• • •••• ••• •••••• ••• • • PAW-M/LK CHEESE • • • • • • • • • • • • • • • • • .iltiii... 77 76 79 60 81 62 63 84 SS 66 67 86 89 TOT/4L. ^CO&tt. 90 91 92 33 Fig. 6.— Distribution of total scores of pasteurized and raw milk cheese. In lot 3B the 10 pasteurized-milk cheeses scored the highest in every case, the average being 7.7 points higher. The average score of the pasteurized was 90.30, and of the raw 82.60. In lot 4B the 10 pasteurized-milk cheeses scored the highest in every case but one, and averaged 85.62, while the 10 raw-milk cheeses averaged 82.10, a difference of 3.52 points. From the results shown in Tables 40 and 41 and in figure 6, it is clear that after storage in the South the pasteurized-milk cheese came out better in quality than the raw-milk cheese made from the same milk. It is not intended to suggest that cheese could be shipped to the Southern States with the express intention of storing it for one month before it is sold, but it is clear that during the few days or Weeks necessarily elapsing after market cheese reaches its destination in the South and before it is eaten, the pasteurized-milk cheese is less likely to undergo serious deterioration than the raw-milk cheese. 79994°--Bull. 165—13 6 B2 ('II EDDAR the pasteurized cheese scored higher than the raw in every case bul one, averaging 90.52, while the raw-milk cheese averaged 86.15, as shown in Table 13. Taiu.k to. /raw and past* wrized milk cheat {lott 3D and 4D) stored in warm room ai Madison. LOT Ml). M OBSD M '.. H, 1911. Date made. Che Mo." Total Total Bra! total 1911. * May 22 230 87 ^: 22 86 R6 80 25 233< ' M BO 80 iQ M 83 84 29 234C BS BS 86 June 1 237 M 84 1 237C SO BO BO 2 80 81 80. S 2 B6 7 240 '.»4 <»4 84 7 240C 78 78 711 g 242 9 242C BS 13 243 80 13 243C BS 16 24S 87 38 B7. 5 15 24SC 85 16 ?46 ns v7 16 87 u 86 LOT 41' 1 l*T. 18. l'.Ml. Jum 18 *48 91 MJ 81.78 Ifl 248C BS BS 21 250 B8 B8 21 B8 253 B8 B8 88 28 BS 27 81 81. 5 27 254C BO B9 Bl 89 28 2554 ' Jillv A :< 2881 ' B7 88 B 81 BLS B Bfl 10 10 261C VI B7 38 11 84 84 84 11 88 B8 B7 12 12 86 87.5 udieatos raw-milk cheese. CHEESE CURED IN COLD STORAGE. 85 CHEESE CURED IN COLD STORAGE. Lot J^E.— Since much of the cheese made by the ordinary process is put into cold storage at about 34°, and most cheese dealers have cold-storage warehouses, a study was begun of the effect of cold storage on pasteurized-milk cheese. The milk supply was so short at the time thai raw-milk cheese could be made on only a few days. Six or seven pasteurized-milk cheeses were made in one vat each day and placed in the curing room at Madison, and single cheeses were shipped to a cold-storage warehouse at Waterloo, Wis., at different ages. Alter about three months the cheese was all shipped back to Madison in one consignment and examined by the judges. One ch>ese from each day's make was kept at Madison during the entire period Table 44. — Scores of pasteurized and raw milk cheese (lot 4E) put into cold storage at different ages and scored Oct. SO, 1911. Age when stored. Scored by U. S. Baer. Scored by A. T. Bruhn. Average score. Date made. Cheese No.' Flavor. Tex- ture. Total. Flavor. Tex- ture. Total. Flavor. Tex- ture. Total. 1911. July 20 20 264.1 42.00 28.00 95.00 42. 50 27.00 94.50 42.25 27.50 94.75 264.2 i day.... 41.00 26.50 92.50 40.50 27.00 92.50 40. 75 26.75 92.50 20 264. .3 1 week . . 40.00 26.00 91.00 40. 50 27.00 92.50 40.25 26.50 91.75 20 264.4 2 weeks. 41.00 28.00 94.00 41.00 27.50 93.50 41.00 27.75 93.75 20 264.5 4 weeks. 41.00 28.00 94.00 42.00 28.00 95.00 41.50 28.00 94.50 20 264.6 6 weeks. 41.00 28.00 94.00 42.00 27.50 94.50 41.50 27.75 94.25 20 265.1 41.00 27.00 93.00 41.00 26.50 92.50 41.00 26.75 92.75 21 265.2 1 day 40.00 27.00 92.00 41.00 26.50 92.50 40.50 26.75 92.25 21 265.3 1 w T eek . . 42.00 28.00 95.00 42.00 28.00 95.00 42.00 28.00 95.00 21 265.4 2 weeks. 40. 00 27.00 92.00 40.00 27.00 92.00 40.00 27.00 92.00 21 265.5 4 weeks. 40.00 27.00 92.00 40.00 27.00 92.00 40.00 27.00 92.00 21 265. 6 4 weeks. 40. 00 27.00 92. 00 41.00 27.00 93.00 40.50 27.00 92.50 25 265.7 6 weeks. 41.00 28.00 94.00 42.00 27.00 94.00 41.50 27.50 94.00 25 25 267.1 267.2 41.00 40.00 28.00 26.00 94.00 91.00 42.00 40.00 27.00 26.00 94.00 91.00 41.50 40.00 27.50 26.00 94.00 91.00 1 day — 25 267.3 1 week . . 41.50 27.00 93.00 41.50 27.50 94.00 41.50 27.25 93.75 25 267.4 2 weeks. 40.00 27.00 92.00 41.00 27.00 93.00 40.50 27.00 92.50 25 267.5 4 weeks. 41.00 27.00 93.00 40. 50 27.00 92.50 40.75 27.00 92.75 25 267.6 6 weeks. 42.00 27.00 94.00 42.00 27. 50 94.50 42.00 27.25 94.25 25 267C1 36.00 26.00 87.00 36.00 26.50 87.50 36.00 26.25 87.25 25 267C2 1 day 38.00 27.00 90.00 39.00 27.00 91.00 38.50 27. 00 90.50 25 267C3 2 weeks. 38. 00 27.00 90.00 38. 50 27.00 90.50 38.25 27.00 90.25 27 27 269.1 269.2 40.00 40. 00 27.00 27.00 92.00 92.00 41.00 40.50 26.50 26.50 92.50 92.00 40.50 40.25 26.75 26.75 92.25 92.00 1 day 27 269.3 1 week . . 40.00 27.00 92.00 40.50 26.50 92.00 40.25 26. 75 92.00 27 269.4 2 weeks. 41.00 27.00 93.00 40.00 26.50 91.50 40.50 26.75 92.25 27 269.5 4 weeks. 41.00 27.00 93.00 42.00 27.00 94.00 41.50 27.00 93.50 27 269.6 6 weeks. 42.50 28.00 95.50 42.50 27.50 95.00 42.50 27.75 95.25 27 269C1 2 weeks. 34.00 23.00 82.00 32.00 25.00 82.00 33.00 24.00 82.00 Aug. 1 1 272.1 272.2 35.00 36.00 23.00 25.00 83.00 86.00 36.00 36.00 25.00 25.00 86.00 86.00 35.50 36.00 24.00 25.00 84.50 86.00 1 day.... 1 272.3 1 week.. 37.00 25.00 87.00 39.00 24.00 88.00 38.00 24. 50 87.50 1 272.4 2 weeks. 38.00 25.00 88.00 38.00 25.00 88.00 38.00 25.00 88.00 1 272.5 4 weeks. 35.00 25.00 85.00 36.00 24.00 85.00 35.50 24. 50 85.00 1 272.6 6 weeks. 37.00 24.50 86.50 38.00 25.00 88.00 37.50 24. 75 87.25 8 8 276.1 276.2 37.00 40.00 25.00 26.00 87.00 91.00 39.00 40.00 26.00 26.00 90.00 91.00 38.00 40.00 25.50 26.00 88.50 91.00 *i day.'.'.". 8 276.3 1 week.. 40.00 25.00 90.00 39.50 25.50 90.00 39.75 25.25 90.00 8 276.4 2 weeks. 40.00 24.00 89.00 39.00 25.00 89.00 39.50 24.50 89.00 8 276.5 4 w r eeks. 40.00 27.00 92.00 39.50 26.50 91.00 39.75 26.75 91.50 22 22 283.1 283.2 41.00 40.00 27.00 26.00 93.00 91.00 41.50 40.50 26.50 26.00 93.00 91.50 41.25 40.25 26.75 26.00 93.00 91.25 i day.... 22 283.3 1 week.. 42.00 27.00 94.00 41.00 27.00 93.00 41.50 27.00 93.50 22 283.4 2 weeks. 40.50 27.00 92.50 41.00 26.50 92.50 40.75 26.75 92.00 22 283.5 4 weeks. 42.00 27.00 94.00 41.50 27.00 93.50 41.75 27.00 93.50 22 283.6 42.00 27.00 94.00 42.00 26.50 93.50 42.00 26.75 93.75 » "C" in this column indicates raw-milk cheese. 86 OHEDDAH I'HKKSK r'lio.M I'ASTKT HI/.KD MIIK. In everj case the pasteurized-milk oheese put into coW Btorage at the age of one da\ was criticized by the judges as being Hat, Low, and not developed in flavor, and the texture was described as curdy, new, not broken down, not cured, etc. Thej received an average Bcore of 90.84, as shown in Table 1 1. Tin- cheeses put into cold storage at the ageof one week received an average score of 91.93. They were found to be well cured, and they had Less mold on the Burface (practically none, both when put into Btorage and when taken out, than any of the later lots. The cheeses put into storage al two weeks, four weeks, and six weeks of age were given average scores of 91.36, 91.82, and 91.46, respectively, While those kept at Madison for the entire period BCOred 91.39. So far as this short series indicate-, there is no objection to putting pasteurized-milk cheese into Btorage at :i4°, at the age <>f one week, immediately after paraffining. Jt was planned, however, to make a more extensive trial of the use of cold Btorage for pasteurized-milk cheese during the season of L912. BXCEFTIONAX DirFBRBMCSfl BETWEEN nil. raw a\i> PASTEURIZED MILK cm It is of interest to collect in one place all of the cases recorded in the tables where the pasteurized-milk cheese was scored lower than the raw, in order if possible to locate the cause for such difference. Table 45. Summary of cases in which rau-mill; cheese scored higher than pasteurized. LotslA,2A,SA,4A. LotslB,2B,3B.4B. Lots 81 Lot- 3D, 4D. Total No.' Total Score. Cheese No.' Total Cheese No.i 171 •171C 172 • 172( 177 • 177C 183 »183C 184 L84C 188 1 i w ' • 260C 261 MIC 81.00 87.00 81.00 83.00 86.00 79.00 85.50 84.50 83.50 7S.50 80.00 81.50 85.00 81 00 17.' 1720 177 177C 183 '- 184C 188 l.SNC 261 261C 91.75 89.00 91.25 91.78 92.00 92.75 94.50 90.50 91.75 87 50 90.25 90.00 an « 261 C Jul »261C S5.50 85.00 88.00 i "(•• Indicates raw-milk cheese. ■ These are the cases hi which the raw-mil] red higher than the pasteurized. The other scores of duplicate cheese in the other lots are given for comparison. 'Hie fact thai pasteurized and raw cheese from the same milk may occasionally Bcore exactly alike or nearly alike would appear to indi- cate that where the milk supply is excellent the quality of cheese pro- duced is not unproved by the new process. With so small a differ- ence m score as half a point, occurring in No. 184 in lot A and No. DISCUSSION el en BESE S< DEES. 5" 177 in lot B, it is doubtful whether bhere was anj difference betwees the two cheeses which could be ascribed with certainty to the effect of the pasteurization process. The most adverse criticism on the process that can be based upon the LO cases tabulated above is the following: It is entirely possible that sonic harmful bacteria or their enzvms which are occasionally present in dirty milk may not be destroyed by the pasteurization process and that such infections damage the quality of pasteurized- milk cheese as well as raw-milk cheese. In this year's work it has been noticed that on a few occasions when the raw milk was very ripe the quality of cheese produced, even after pasteurization, was not so good as from milk of fairly good quality. For example: The poorest pi steurized-milk cheese in Table 45 is No. 261, and the milk used for making this was of 0.28 per cent acidity before pasteurization. In Table 44, showing the scores of cheese shipped to cold storage, Nbs. 272 and 276 are the poorest in quality and these were made from milk which titrated 0.275 and 0.31 per cent acidity, respectively, before pasteurization. Of course such milk should not be accepted at any cheese factory. No claim is made that the pasteurization process is a cure for all the troubles of the cheese factory, or that it reduces the responsibility resting on factory patrons to improve the sanitary quality of their milk. It would, in fact, be most unfortunate if any process could be used for making cheese, or any other article of food, which would relieve the milk producer or the factory man of the necessity for cleanliness. SUMMARY OF DISCUSSION OF SCORES. The scores of lots IB, 2B, 3B, and 4B, 3C and 4C, and 3D and 4D all show that cheese, either raw or pasteurized, stored for one or two months at about 80° are often seriously injured, so as to be unsalable at the ruling market price. The pasteurized cheese came out of such storage better in quality than the rawvmilk cheese in about 90 per cent of all the cases observed. It is clear that pasteurized-milk cheese is better suited to stand exposure to high temperature than raw-milk cheese. This fact may find useful application in two ways: While it is never advisable to store market cheese for any great length of time in the South, yet several days or weeks may often elapse before cheese shipped South is finally sold to the consumer, and it appears that pasteurized-milk cheese should stand this ex- posure with less damage in quality than raw-milk cheese. It is likely, too, that pasteurized-milk cheese can be cured at ordinary curing-room temperatures below 70° in Wisconsin without the use of ice or mechanical refrigeration, thus avoiding part of the expense for cold storage. The quality of the 53 raw-milk cheeses in lots 1A, 2 A, 3 A, and 4A, cured at 60° to 73° at Madison, is represented by the CHBDDAB OHBBSB ii;<»m PAfl I i.l'iil/l.D MILK. average total score of 89.09, and would no doubt have been greatly improved if the cheese bad been cured in cold storage. In 51 i out of 53 the pasteurized-milk cheese In these lots scored lugher khan the raw, on the average 3.8 points higher, the average total score of the pasteurized being 92.76 points, which indicates that cold storage for the pasteurized cheese was not necessary. In a short series of cheese placed in cold Btorage at 34° F. at dif- ferent ages, it was found that those stored at the age <»f one day were CUrdy and uncured at the age Of three months, while those placed in Btorage at the age Of one week were free from this fault and scored as high, even a little higher, and showed les^ mold on the surface than those put in storage when older than one week. From this it appears that pasteurized-milk cheese can he safely put in cold Btorage at the age of one week immediately aft or paraffining. It was planned to try cold storage with hoth raw and pasteurized-milk cheese during 1912. THE DEMAND FOR PASTEURIZED-MILK CHEESE. One of the objects of the work during 1909, 1910, and 1911 was to sell the cheese to consumers as widely as possible, and learn whether it WOUld meet with favor and continued demand. It was felt neces- sary thus to establish its suitability for the market before recom- mending cheese makers to take up the new process. The amount of pasteurized-milk cheese sold each year was limited by the output of the factory, it being impossible to secure a larger supply of milk. Much more cheese could have been sold to the same purchaseis. and doubtless to others, if we had had the cheese to sell. In nearly all cases the cheese was sold at the current price ruling on the Plymouth cheese board, f. o. b. Madison without discount. During 1910. 4.S15J pounds of pasteurized-milk cheese valued at $711.1(3 were sold to 19 representative grocery stores. hotels, restaurants, and delicatessen stores in Madison. Wis. The total number of such sales was 137 during the season. Nearly every purchaser reordered it several times, and three of the leading retailers reordered it 15. 20, and 49 times, respectively, during the season. The average price paid for all of this cheese was 14J cents per pound. During 1900, 1911). and 1911, 41 shipments of pasteur- ized-milk cheese weighing 10,126 pounds in all and valued at $1,382.93 were sent to 27 leading cheese dealers, including a few retail store-, at New York, Boston, Philadelphia, Chicago, St. Louis. Minneapolis, and San Francisco, and at various Wisconsin points outside of Madison, including Plymouth, Sheboygan, Fond du Lac Marshfield, Richland Center. Waterloo, and Milwaukee. Samples of the cheese were also Bhipped to expeiiment station workers in the leading dairy States for an examination. EXTRA COST OF PASTEURIZED Mil K CIIKESE. 89 OPINIONS OF PURCHASERS. No written opinions were asked from dealers in Madison handling the pasteurized-milk cheese, neither were they urged bo purchase a second time. The university delivery wagon making two t rips daily among retail stores took such orders as were given. The fact that a dealer bought this make of cheese only once may be due to a variety of causes, such, for example, as business relations with other wholesale cheese dealers in the city. The fact that several of the leading grocers sold tins cheese continuously for several months and repurchased it every week or oftener, and always without reporting any complaint from consumers, is taken to indicate that it was satisfactory to the retail trade of this city. An effort was made to obtain a written opinion from every firm outside of Madison to whom the cheese were sold. It was usually impossible to send many shipments to a single purchaser, because it was desired to distribute the available supply of cheese as widely as possible. The letters received from dealers outside of Madison show that all except a very few found the cheese to be entirely satisfactory, and salable at the full market price. Here again the occasional disap- proval of a cheese may be due to an oversupply in the buyer's ware- house, or other causes than the quality of the cheese iteslf. It is interesting to note that pasteurized-milk cheese shipped to two firms who apparently disliked it was the same day's make as others shipped on the same date to three other firms who praised their quality and pronounced them satisfactory. In every case dealers were informed that the cheese "was made by special process, which we are trying at Madison, by which it is hoped that cheese of cleaner flavor and greater uniformity can be obtained. " In no case were dealers in- formed as to the nature of the process or that the milk was pasteur- ized. The purpose was to excite the dealers' interest and secure careful examination of the cheese, unqualified by any prejudice for or against pasteurization. The very general expression of approval of the product in the let- ters from dealers and experiment stations appears to warrant fur- ther trial of the method on a larger scale than heretofore. THE EXTRA COST OF MAKING PASTEURIZED-MILK CHEESE. While it has been shown that an increased yield of cheese is ob- tained there are also additional costs, which must be charged agamst the cheese made by this method. Such costs will include the interest on investment, and depreciation, of a pasteurizer, cooler, and receiv- ing vat, a charge for the hydrochloric acid used and for the expense of steam heat and power for pumping water for cooling the pasteur- ized milk, and for running the pasteurizer. '.ill OHEDDAB CHBS8E PROM PASTEURIZED MH.K. Preliminary estimates, based upon available data, seem to indicate that ilif extra cost of making pasteurized milk cheese is less than the additional value of the cheese, Leaving a net profit from tlic 1186 of the process, as compared with the regular factory process. Since the Bteam and water supplies used in the work at Madison were drawn from the general Bervice pipes of the Wisconsin Agricultural Experi- ment Station it was impossible to determine these items of cost with exactness. In order to ascertain precisely what the charges for Bteam heat. power, etc. are at an average cheese factory in Wisconsin, a c. m- plete ontlit for making pasteurized-milk cheese will he Bet up at a country cheese factory, easily accessible from Madison, and operated 1>\ an experienced and successful cheese maker. Cheese will be made there by both the regular factory method and by the new method in order to ascertain more fully the cost of making, the increased yield, and the market value of pasteurized-milk cheese. FUETHEB TRIALS OF THE NEW PROCESS IN < EEESE I A< M>i:h The results described in this bulletin appear to indicate that the new method of cheese making is an improvement over the regular process now commonly used. Working with the milk supply avail- able at Madison, the new method is unquestionably an improvement over the old. It is a fact well known to cheese makers, however, that the milk supplies found at different factories d<> not always behave alike in the cheese vat, so that the old process must frequently be modified to suit the conditions encountered in different Localities. It remains, therefore, to test the new method at several factories in dif- ferent cheese-making districts before it can be recommended for use generally. Cheese maker- are advised to await the publication of results of further trials before undertaking to use the new method on a commercial scale. It is hoped that the new method will receive careful attention and criticism by such cheese experts at experiment stations in different parts of the country as may be able to give it a trial. The authors will be glad to correspond with any one interested and to aid in such trials so far as circumstances permit. SUMMARY. l'hlilMlNAKY AND COMPARATIVE WORE Willi THE OLD AND NEW M LTHODS. The continued improvement of the cheese-making industry calls for more economical factory management. Large, well-equipped facto- ries should replace many of the small, poorly supported factorii the present time. SUMMARY. 91 To enable cheese factories to handle milk from larger areas of ter- ritory, and for other reasons also, a new method of cheese making is needed by means of which milk of variable quality from inan\ farms can (1) be brought into practically uniform condition for cheese making at the factory, and (2) can be made up into cheese in a uni- form, routine manner daily without variations of time or method of handling; also (3) cheese of greater uniformity should be produced. and (4) the losses in yield and quality of cheese due to defective milk, now common in factories, should be avoided. During the years 1905 and 1906 experimental cheese was made without starter, adding in its place to the raw milk some commercial acid, as hydrochloric acid or other kinds. The method of adding the acid to milk was perfected, and a two weeks' trial of the process was finally made in a commercial factory at Muscoda, Wis. It was show n clearly that the addition of hydrochloric acid to milk in a cheese fac- tory is entirely practicable and that the quality of the cheese is not in any way injured by such addition, but it was also found that the quality of cheese obtained from overripe or tainted milk was no bet- ter than by the use of the ordinary factory methods. Therefore, there was no reason for recommending the use of hydrochloric acid to cheese makers at that time. Most of the defects observed in cheese-factory milk are of bacterial origin, and in other branches of the dairy industry pasteurization is successfully employed to overcome these faults. The desirability of pasteurizing milk for cheese making, if possible, has often been pointed out. In 1907 a few lots of milk were pasteurized in a discontinuous pasteurizer and acidulated with hydrochloric acid, and the cheese obtained was such as to demonstrate the importance of further study. In 1908 equally good results were obtained by use of the contin- uous pasteurizer. A temperature of 160° to 165° was decided upon as being sufficiently high to effectually check bacterial action in milk for cheese-making purposes. Bacterial counts showed that over 99 per cent of the total bacterial content of the milk was de- stroyed at this temperature. The use of higher temperatures was shown to be objectionable on account of the effect upon the quality of the cheese. In 1909 cheese was made almost daily both by the regular factory process and by the new process from pasteurized milk. The regular milk supply was thoroughly mixed each day and divided into two lots for the two different processes. The cheese made from pasteur- ized milk was found after curing to be cleaner in flavor and superior in texture to the raw-milk cheese. The difference was more marked the poorer the quality of the milk supply. Many of the details of the process were studied and improved. 92 OHEDDAB CHEESE PBOM PASTEURIZED MILK. In 1910 the making of cheese by the two methods for comparison was continued, and the emir*' output of pasteurized-milk cheese was Bold to retail grocers, mostly in the city <>f Madison, in order to determine bo* tins cheese would suit the trade. The cheese met With read} and continued sale. It w.is noticed also that the yield of cheese was. regularly, somewhat greater by the new process than l>\ the old. In mil better facilities were provided for weighing Large quan- tities of milk and cheese (juieklv and accurately, and the yields of cheese obtained from raw and pasteurized milk were carefulU de- termined. The accuracy of the experimental methods was such that in making duplicate vats of cheese from pasteurized milk the yields differed l>y only 0.58 per cent on the average. A greater yield of cheese was always obtained from the pasteurized milk than from law milk, and during the year 1911 the average ,L r ain in yield of green cheese was ">.:;7 per cent. However, the green pasteurized- milk cheese shrank a little more than the raw-milk cheese, BO that when paraffined the average gain in yield from pasteurized milk was 4.76 per cent. After curing cheese at 60° to 70° F. for about loo days, the gain in yield of pasteurized-milk cheese over tin- raw was 4.22 per cent. SOME ADVANTAGES FROM THE USE OF PASTEl'lM/ED MILK AND HYDRO- CHLORIC ACID. The average loss of fat in whey from pasteurized-acidulated milk is about ets of cheese were cured at New Orleans for one month at 70 to 83 (monthly average Bgures during the summer), and here the raw milk Lost more in weight than the pasteurized, so thai the average gain in yield of pasteurized over raw rose to 6.21 per cent. OUTLINE OF THE NEW METHOD. 93 From other cheese cured at Madison on tin pans in a warm room, it was Learned that the raw-milk cheese lost considerable amounts of fat at 75° to 85° while the pasteurized-milk cheese lost none. Storage for a month at an average temperature of 75° to 80° at New Orleans is not recommended for any cheese, yet it was found that pasteurized-milk cheese averaged 3 to 8 points better in total score after such storage than raw-milk cheese. Since pasteurized-milk cheese can be cured without injury at 70°, it is likely that in most cases the expense of cold storage for this cheese can be avoided. Pasteurized-milk cheese can be put into cold storage at 34° at the age of one week and possibly earlier without injury. The earlier the cheese can be put in storage, if this is done afc all, the greater will be the gain in yield by the new process. It is planned to study the cold storage of this cheese further. During 1910-1911 about $2,100 worth of pasteurized-milk cheese was sold to about 50 dealers, both wholesale and retail, in various large cities from New York to San Francisco. The cheese sold readily for the ruling market prices and often above. Very few dealers offered any objections to them and several wished to buy them regularly. A good many were sold throughout the South by dealers. In general, the cheese passed through the market without exciting special comment, selling for full price and giving satisfaction. They were not labeled or marked except with a number for purposes of identification. There appears to be no reason why pasteurized- milk cheese can not be sold regularly in any market with entire satisfaction, excepting possibly to the limited trade that demands very high-flavored cheese. OUTLINE OF THE NEW METHOD. In the method here described a principle is applied to the cheese- making process which has already been found useful in many other lines of manufacture, namely : The raw material, milk, is first treated by a preparatory process to bring it into uniform condition before it enters the manufacturing process proper. Material of uniform quality thus prepared is made up into the finished product by a uniform routine process without daily variations of the time schedule or other details, and the product is more uniform in quality, has better keeping qualities, etc., than the product obtained by the older process. The difficulties met with hitherto in making American Cheddar cheese from pasteurized milk are: First. That heated milk coagulates poorly with rennet; and Second. The curd when obtained does not expel moisture pre- cisely as a raw-milk curd does, and this effect is more marked the 9 1 OHEDDAB 0HBB8B FROM PASTEURIZED MILK. higher the temperature of pasteurization. The quality and behavior of pasteurized-milk curd Buggest that it Lacks the acid which is normally produced in raw-milk curds by the action of bacteria on milk sugar. The first of these difficulties, but not the second, can be over- come by adding calci um-chlorid solution to pasteurized milk. This method has been tried experimentally, hut is not recommended for use m American cheese factories. Both difficulties, however are over- came by adding an acid, preferably hydrochloric, to the pasteurized milk. Hydrochloric acid Lb normally present in the human stomach during the process of digestion in larger proportions than that added to milk in this pi cheese making. Further, 95 per cent of the added acid passes out of the cheese with the whey during tin' process of manufacture. On this account no objection can he made on sanitary grounds to the use of this acid in the manner and for the purposes described. Among different lots of cheese part of winch was made with hydrochloric acid and part with calcium ehlorid added to portions of the same milk after pasteurization, those made with acid were found to he more uniform in moisture content and superior both in flavor and texture to those made with calcium cldorid. The 1 of fat in the whey are reduced by the use of the acid. Pasteuriza- tion and acidulation of milk for cheese making appear to be com- plementary processes. Used together they furnish a means for bringing milk daily into uniform condition both as to acidity ami bacterial content for cheese-making purposes. The acidulation of milk with hydrochloric acid after pasteuriza- tion is accomplished without difficulty or danger of curdling by running a small stream of the acid, of normal concentration, into the cooled milk as it flows from the continuous pasteurizer into the cheese vat. One pound of normal-strength acid is sufficient to raise 100 pounds of milk from 0.16 per cent to 0.25 per cent acidity (calculated as per cent of lactic acid). The amount of acid needed each day to bring the milk up to 0.25 per cent acidity is read from a table or calculated from the weight of the milk and its acidity, determined by the use of Manns's acid test (titration with tenth- normal sodium hydrate and phenolphthalein). Tin 4 preparation <>f Standard-Strength acid in carboy lots for this work and the acidula- tion of milk present no great difficulty to anyone who is able to handle Manns's acid test correctly. After the milk is pasteurized and acidulated three-fourths per cent of first-claSS --tarter is added and the vat is heated to 85°. It i- set with rennet, tiding 2 ounces of rennet per thousand pounds of milk, so that the milk begins to curdle in 7 minutes and is cut with three-eighth inch knives m 25 minutes. All portions of the OUTLINE OF THE NKW METHOD. 95 work after adding rennet are carried out in an unvarying routine manner, according to a fixed-time schedule every day. As booh as the rennet has been added the cheese maker is able to calculate the exact time of day when each of the succeeding operations should be performed, and the work of making the cheese is thus simplified and systematized. It is possible that the routine process here de- scribed may be varied somewhat with advantage at different factories. For example, some experienced cheese makers may prefer to mat the curds on the bottom of the vat instead of on racks or may find the use of the "curd gauge" unnecessary, and local conditions may be found in different factories making other adjustments of details desirable. However, the experience already had with the process indi- cates that the routine of daily operations found suitable at any fac- tory can be practiced there throughout the season without variation. It is the intention to give the new process a thorough trial in different cheese factories in various localities to test its applica- bility to different milk supplies before recommending it for general use by cheese makers. These trials will show whether new diffi- culties may arise winch were not encountered heretofore. Cheese makers are therefore advised to await the publication of results of further trials of the method by the writers before undertaking to use the new process at their factories. The extra cost of making pasteurized-milk cheese is being studied with a view to finding out accurately what the net profit is in making this cheese compared with the regular process. The new process should interest the farmer because of the increased yield and the avoidance of the usual losses in yield and quality of cheese due to defective milk. It should interest the cheese maker because the process of making is systematized to such a degree that it is conducted upon a fixed-time schedule for all operations. It should interest the dealer because the cheese is more uniform in quality and there is less need for cold storage in curing. Finally, the cheese should interest the consumer, because it is more uniform in flavor than most of the cheese to be found on retail counters and because it is made from pasteurized milk and is therefore a more sanitary product than ordinary American cheese made from raw milk. ADDITIONAL COPIES of this publication ii- may be procured from the Superintend- ent of Documents, Government Printing Office. Washington, D. C, at 15 cents per copy UNIVERSITY OF FLORIDA nun ii 111 1 1 3 1262 08928 6537