Class .^ ^ Book fopyriglit}!! Ci)FIRIGHT DEPOSm An Ice Cream Laboratory Guide BY W. W. FISK Assistant Professor of Dairy Industry at Cornell University and H. B. ELLENBERGER Instructor of Dairy' Industry at Cornell University NEW YORK ORANGE JUDD COMPANY 1917 -^^1 f*^ Copyright, 1917, by ORANGE JUDD COMPANY All Rights Reserved SEP 26 1917 If DMd Printed in U. S. A. ©C1.A476258 TABLE OF CONTENTS PAGE Preface ..... i Discussion of Laboratory Equipment 3 Exercise I Inspection and Study of Ice Cream Machinery .... 6 Discussion of Standardization 8 Exercise II Standardization 12 Exercise III Testing Ice Cream for Fat 14 Exercise IV Effect of the Salt and Ice Mixture on Temperature . . 16 Classification of Ice Cream 18 The Use of Stabilizers 21 Exercise V Freezing Plain Ice Creams 24 Exercise VI Methods of Measuring Swell 26 Hardening Ice Cream 28 Exercise VII Freezing Fruit Ice Cream. Hardening in Salt and Ice . 30 Exercise VIII Freezing Nut Ice Cream 32 Exercise IX Freezing Bisque Ice Cream 34 Exercise X Making Bricks and Fancy Moulded Ice Creams » • . Z7 Exercise XI Freezing Custard Ice Cream 41 Exercise XII Freezing Parfait or French Ice Creams 45 Exercise XIII Freezing Puddings 49 Exercise XIV Freezing Ices . 52 ill CONTENTS PAGE Exercise XV Freezing Water Sherbets 54 Exercise XVI Freezing Milk Sherbets 56 Exercise XVII Freezing Punches and Lacto 58 Exercise XVIII Freezing Mousse 60 Exercise XIX Standardize Mix to a Given Percentage of Fat .... 62 Score Card for Judging Ice Cream , . 64 Exercise XX Judging Plain Ice Creams 66 Exercise XXI The Effect of Fat Content on Ice Cream 68 Exercise XXII The Effect of Different Binders on Ice Cream .... 70 Exercise XXIII The Effect of Varying Percentages of Milk Solids Not Fat on Ice Cream "jo. Exercise XXIV Freezing Ice Cream from Raw, Pasteurized, Emulsified and Homogenized Cream 74 Exercise XXV The Effect of Aging Cream on the Viscosity and Swell . 76 Exercise XXVI The Effect of the Temperature of the Mix as It Enters the Freezer on the Swell 78 Exercise XXVII Effect of the Time of Freezing on the Swell and Quality of the Ice Cream 80 Exercise XXVIII Bacterial Counts of Ice Cream 82 Exercise XXIX Testing Samples of Gelatin 84 Exercise XXX Trip to Commercial Plants 86 Exercise XXXI Students' Receipts 88 PREFACE The manufacture of ice cream is based on certain scientific principles. It is the purpose of this labora- tory manual to help the student to better understand the application of these principles. This manual, which is the result of several years' experience in teaching, is not intended as a textbook, but as a brief and concise outline of laboratory exercises. It will also serve as a suitable place for the student to record observations. The exercises have been prepared, so that each instructor may make selections and combina- tions suitable for the equipment and the needs of his course. Because this is comparatively a new subject and the ideas regarding ice cream production and manufacture are constantly changing, the authors recognize that this manual will need frequent revisions. An effort will be made to keep it thoroughly up to date. Dairy Laboratories, Ncit York State College of Agriculture, at Cornell University, Ithaca, New York, February, J917. An Ice Cream Laboratory Guide LABORATORY EQUIPMENT The exercises in this manual may be selected or easily modified, so that they will be suitable for any laboratory equipment. For example, the receipts have been prepared with the expectation that a 10-gallon freezer would be used ; if a smaller freezer is used, the receipts may be reduced proportionally. Much better instruction can be given if the equip- ment includes an artificial refrigerating plant for freez- ing and hardening the ice cream. If the equipment does not include an artificial refrigerating plant, a tub and can freezer, using an ice and salt mixture for freezing, and a wooden box for packing and hardening the ice cream, in ice and salt, may be used. The hardening box should be made of 2 inch matched lumber so that it will not leak. The size of the box will be determined by the amount of ice cream manu- factured. It should be built in compartments which will hold six five gallon cans. This will require a box 26 inches wide by 32 inches deep by 36 inches long, outside measurement, with a hinged cover for each compartment. If much ice cream is to be made an ice cream mixer is a necessity, but if a small amount is made each batch may be mixed in a 40 quart milk can. A homogenizer and emulsor may be included in the equipment. With whatever type of freezer is used, there should be one or two small hand freezers, to freeze small 3 4 AN ICE CREAM LABORATORY GUIDE batches and to try new receipts. An ice crusher should be included for crushing ice. The equipment should include the necessary small utensils, such as pails, dippers, ladles, spoons, ther- mometers, scales, measures, pack cans, etc. There should be a suitable sink connected with hot and cold water and steam, for washing and scalding the utensils. A suitable rack should be provided for drying and holding the utensils and pack cans. Be- cause of the salt used, care must be exercised, as it is liable to get on the utensils and cause them to rust. All belts and gears on machines should be protected, so that persons cannot be caught and injured in them. AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER I INSPECTION AND STUDY OF ICE CREAM MACHINERY Artificial refrigerating systems. I. State briefly the principles involved in an arti- ficial refrigerating plant. 11. Make drawings showing the working principles of the refrigerating system. III. Tell how to start and stop the compressor. Ice cream freezers. I. Tell the principles on which the various types of freezers work. II. How can the temperature in the different types of freezers be regulated? Cleaning utensils. I. How should utensils be washed? Why? II. Are all utensils so constructed that they may be easily and thoroughly cleaned? What provisions have been made to make cleaning easy ? AN ICE CREAM LABORATORY GUIDE EXERCISE I REPORT AN ICE CREAM LABORATORY GUIDE STANDARDIZATION One of the main requirements for a successful ice cream business is uniformity of quality. In order to obtain this, it is necessary to have cream each time containing the same percentage of fat. As it is im- possible to always get cream of a uniform fat content, the cream must be standardized. That is, the percent- age of fat must be either increased or decreased to the desired amount. It is the usual practice to have richer cream than is to be used and reduce it by the addition of less rich cream, whole milk, or skim milk. If the cream was lower in percentage of fat than was desired, it could be standardized only by the addition of richer cream. Prof. R. A. Pearson has devised a very simple method, known as the rectangular method of standard- ization. This method is as follows : draw a rectangle and place in the center the percentage of fat desired. At the left hand corners place the percentages of fat in the materials to be mixed. It is customary to place the larger figure at the top, thus: 16 parts of] 25% cream] 5 parts of milk = 21 parts "of 20% cream Then subtract diagonally, placing the remainders at the right hand corners, as shown above. These AN ICE CREAM LABORATORY GUIDE Q show the proportions by weight in which the materials must be mixed to give the desired percentage of fat. A problem may serve to illustrate the method. How many pounds each of 30% cream and 4% milk are necessary to make 260 lbs. of 20% cream? This shows 16 lbs. 30% cream and 10 lbs. 4% milk make 26 lbs. of 20% cream, but 260 lbs. is required. This is best solved by simple proportion: 10 lbs. milk : 26 lbs. 20% cream : : x lbs. milk : 260 lbs. 20% cream. Solving X = 100 lbs. 4% milk required and 260 lbs. — 100 lbs. milk = 160 lbs. 30% cream required which may also be determined by proportion. To be sure no mistakes are made in figuring, it is best to prove all standardizations. The proof is simple. • 260 lbs. 20% cream contains 52 lbs. fat (required). 160 lbs. 30% " " 48 lbs. " 100 lbs. 4% milk " 4 lbs. " Making a total of 52 lbs. fat, the amount required. In the above problem a definite amount of the mix- ture was required. There is another class of standard- ization problems in which the amount of one of the lO AN ICE CREAM LABORATORY GUIDE materials is given, to find the quantity of the other re- quired to standardize it: How much 4% milk must be mixed with 420 lbs. of 40% cream to make a mixture testing 25% fat? This shows that 15 lbs. of 4% milk will standardize 21 lbs. of 40% cream to a cream tasting 25% fat. But there are 420 lbs. of 40% cream to standardize. By simple proportion, 15 lbs. 4% milk : 21 lbs. 40% cream :: x lbs. 4% milk : 420 lbs. 40% cream. Solving X r= 300 lbs. 4% milk 420 lbs. cream + 300 lbs. milk = 720 lbs. 25% cream. Proof : 720 lbs. of 25% cream contains 180 lbs. fat. 300 lbs. of 4% milk " 12 lbs. " 420 lbs. of 40% cream '' 168 lbs. " Making a total of 180 lbs. fat. 12 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER II STANDARDIZATION Cream and milk to standardize will be furnished. Test both by the Babcock method and report the result to the instructor, who will assign a definite per- centage of fat for the standardized mixture. After standardizing, test a sample of the standard- ized mixture by the Babcock method to test the ac- curacy of your work. Report all calculations and results on opposite page. AN ICE CREAM LABORATORY GUIDE 1 3 EXERCISE II REPORT 14 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER III TESTING ICE CREAM FOR FAT Ice cream cannot be tested for fat, by the Babcock test, as milk, because the acid chars the sugar, which interferes with the reading. Various methods of test- ing ice cream, so as to overcome this disadvantage have been devised. A few of the simpler ones follow. Test a sample of ice cream by each of the following methods and report results on the opposite page. Method of Prof. H. E. Ross: Mix equal parts by weight of melted ice cream and water. Weigh into a 9 gram 50% cream bottle 9 grams of the mixture. Add 17.5 cc. of glacial acetic acid. Shake for two to three minutes. Next add 15 cc. of sulphuric acid such as is used for the Babcock test. Shake for one minute and proceed as in the ordinary Babcock test. Multiply the reading by two. Method of J. P. Dawson: Weigh 18 grams of melted ice cream at a temperature of 70 degrees F. into a 30%, 9 inch cream test bottle. Add 8 cc. of glacial acetic acid, agitate gently for 2 minutes and add 10 cc. of Babcock sulphuric acid. Shake and centri- fuge in the usual manner. Note : There appears to be no reason why one half the quantities of ice cream and acids may not be used in a 6 inch 9 gram 50% cream bottle. Method often used by the authors : Weigh 9 grams of melted ice cream into a 6 inch 50%, 9 gram cream bottle and add about 9 cc. of water. Add three quarters of an acid measure of glacial acetic acid and mix thoroughly. Next add two thirds of an acid measure of Babcock sulphuric acid. Shake till well mixed and centrifuge in the usual manner. AN ICE CREAM LABORATORY GUIDE 1 5 EXERCISE III REPORT It) AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER IV EFFECT OF THE SALT AND ICE MIXTURE ON TEMPERATURE Alake a brine one part salt to ten parts of water by- weight. With part of this fill the can of a hand freezer two thirds full just as though it were an ice cream mix which you were going to freeze. Record the temperature of this brine. Trial 1. Using a mixture of one pound of salt to 10 lbs. of crushed ice, try freezing the brine in the freezer can. Turn 10 minutes, keeping the freezer can well covered with the ice and salt mixture. Open and record the temperature of the brine in the can. Trial 2. Empty the freezer can and tub and refill the can with more of the brine used in Trial 1. Be sure to have it the same temperature. Using a salt and ice mixture of the same proportions, pack the tub again and in addition add enough cold water so that it starts to run from the overflow hole in the tub. Turn the freezer 10 minutes, recording the temperature of the brine flowing from the overflow hole every 2 minutes. Be sure to keep the ice-salt-water mixture in the tub well mixed by punching with a stick such as a sawed- ofif broom handle. Again record the temperature of the brine in the can. Why does it differ from what it was in Trial 1 ? Trial 3. Repeat Trial 2, except use a mixture of salt and ice one to six instead of one to 10. Record results. Trial 4. Repeat Trial 3 but do not mix the ice, salt. AN ICE CREAM LABORATORY GUIDE I7 and water in the tub. Explain the difference in the results obtained in Trials 3 and 4. Tabulate and report all the data which you have recorded. EXERCISE IV REPORT l8 AN ICE CREAM LABORATORY GUIDE CLASSIFICATION OF ICE CREAM In the absence of the adoption of any uniform standard classification of ice cream, the following classification in use by the authors is given. It is simple, yet comprehensive, and is arranged according to fundamental differences in composition. This seems to be the most logical basis for classifying ice cream and is very satisfactory from a laboratory standpoint. Exercises and representative formulas will be given for each of these classes. I. Plain or uncooked ice cream, often known as Philadelphia ice cream, is made from cream, sugar, and flavoring, with or without condensed milk or some stabilizer. It may be subdivided as follows : 1. Plain — Flavors such as Vanilla, Chocolate, Car- amel, Coffee, Mint, etc. 2. Fruit — Flavored with fresh or canned fruits such as Peach, Pineapple, Strawberry, Cherry, etc. 3. Nut — Flavored with such nuts as Walnut, Al- mond, Filbert, Chestnut, Pistachio, etc. 4. Bisque — Flavored with Marshmallows, Maca- roons, Sponge Cake, Nabisco Wafers, Grape- nuts, etc. II. Cooked ice cream, often known as French or Neapolitan ice cream, is made from cream, sugar, flavoring, and eggs. As custards they sometimes con- tain flour or cornstarch. The following subdivisions are recognized: 1. Parfaits or French — Flavors such as Vanilla, Chocolate, etc., are most common, but various fruits are sometimes used. AN ICE CREAM LABORATORY GUIDE 1 9 2. Puddings — These are highly flavored with va- rious dried and candied fruits, nuts, and spices. Examples are Nesselrode, Roman, and Eng- lish Plum. 3. Custards — These contain flour, cornstarch, tapi- oca, or other similar ingredients, and are al- most always flavored with vanilla. III. Sherbets and Ices are made from water or milk, sugar, often egg albumen and a stabilizer, and flavored with fruit juices or other natural flavoring. The most prominent classes are the following : 1. Ices — Made from water, sugar and some natural flavoring without eggs or a stabilizer. This may include granites and frappes. Granites are frozen with little agitation, while frappes are only semi- frozen to a slushy consistency. 2. Water Sherbets — are made the same as ices with the addition of egg whites and sometimes a stabilizer. If the whole egg is used, they are sometimes called souffles. 3. Punches — are ices or water sherbets flavored with liquors or highly flavored with fruit juices and spices. 4. Milk Sherbets — Made from skimmed or whole milk, sugar, and egg whites, with or without a stabilizer and flavored with some natural flavoring. 5. Lacto — Made from skimmed or whole sour milk instead of sweet milk but in other respects they resemble milk sherbets. IV. Mousse is a rich cream, sweetened and whipped to a stifif froth, flavored and frozen in moulds or cans. In the laboratories at the New York state argricul- tural college 20% cream is used in making all plain or uncooked ice creams. Therefore in the following ex- 20 AN ICE CREAM LABORATORY GUIDE ercises and formulas a 20% cream is used as a base in most cases. This, however, may be reduced to 18% or 16% if it is thought desirable. It must be remembered that the formulas given are for laboratory use and are not especially recommended as ideal formulas for commercial use. Many of them have given good results in commercial plants but there are so many variations and combinations possible that no single formula or group of formulas can be given as ideal for all commercial plants. If the use of condensed milk is desired eight pounds of whole condensed milk may be substituted for the same amount of cream with excellent results in any of the formulas given for plain ice cream. Most com- mercial plants use condensed milk to give the ice cream more body and better standing quality. AN ICE CREAM LABORATORY GUIDE 21 THE USE OF STABILIZERS A stabilizer of some kind is generally admitted to be necessary in commercial ice cream. The three most commonly used are gelatin, ice cream powders and gum tragacanth. Gelatin may be prepared in any of the three follow- ing ways, using either milk or water for dissolving it. However, if milk is used, one of the first two methods should be used, so as to avoid any cooked flavor from boiled milk. 1. Using one pint to one quart of water or milk to each two ounces of gelatin, soak the gelatin in the cold liquid for fifteen to thirty minutes. Then heat the mixture up to a temperature of 160 degrees to 170 de- grees F. and add to the cream with rapid agitation. 2. The same as number one, except heat the mix- ture only to a temperature of 125 degrees to 130 de- grees F. for a sufficient time to thoroughly dissolve all of the gelatin. 3. Heat the necessary amount of water to boiling, dump the gelatin into it and stir till dissolved. Then add to the cream with rapid stirring. Ice cream powders should be used according to the directions given with them. Gum tragacanth stock is made in the following manner. Place the dry gum in cold water, using one ounce of gum to four pounds of water. Heat slowly and uniformly over a low flame or better in a double boiler to a temperature of about 110 degrees F. Hold at this temperature for several hours or until the dry gum has absorbed all the water it will hold. It does not go into true solution in water but will absorb about 22 AN ICE CREAM LABORATORY GUIDE fifty times its own weight of the water. Strain through a coarse strainer and cool. It is then ready for immediate use. Sometimes enough is made at one time to last for several days, in which case it is best to add sufficient sugar to keep it from spoiling. 24 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER V FREEZING PLAIN ICE CREAM Freeze ice creams after the following formulas, which may be reduced to suit the capacity of the freezer used. Eight pounds of whole condensed milk may be substituted for eight pounds of the cream if desired. Fill out the rec^ord blank on opposite page. No. 1. 40 pounds* of 20% cream 8 pounds of sugar 4 ounces of vanilla extract 4 ounces of gelatin if desired (See page 21) No. 2. 40 pounds of 20% cream 8 pounds of sugar 2 ounces of vanilla extract 4 ounces of gelatin if desired (See page 21) lj4 pounds cocoa dissolved in four pounds of boiling water with one pound of sugar. (Chocolate may be used.) Cinnamon to taste if desired. No. 3. 40 pounds of 20% cream 8 pounds of sugar 2 ounces of vanilla extract 2 pounds of coffee (boil, strain and use enough to flavor to taste) 4 ounces of gelatin if desired (See page 21) No. 4. 40 pounds of 20% cream 8 pounds of sugar 1 pint of creme de menth syrup 4 ounces of gelatin if desired (See page 21) Color pale green. AN ICE CREAM LABORATORY GUIDE 2^ EXERCISE V REPORT Date Receipt Number CREAM : ICE CREAM : Age Gallons Acidity Weight per gallon Temperature SWELL: STANDARDIZATION: Gallons Per cent. Per cent fat in cream. Per cent fat in milk FREEZING: Standardize pounds of Freezer used cream testing per Pounds ice used... cent fat. Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. That freezing is completed Total time required to Give proportion. freeze X = the pounds . — Pounds of cream used TEMPERATURE Pounds of milk used Of mix entering freezer MIX Of brine when mix reaches Pounds Gallons 30° F Weight per gallon Of ice cream when removed Per cent fat it should test Of brine at this time Was gelatin used? By method 1, 2 or 3? In milk or water? Remarks : Comments on ice cream after it is hardened 26 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER VI METHODS OF MEASURING SWELL Freeze one or more batches of plain ice cream as as- signed and measure the per cent, of swell in each of the following ways. Record results on the opposite page. Receipt: 40 pounds of 20% cream 8 pounds of sugar 4 ounces of vanilla extract 4 ounces of gelatin if desired (See page 21) 1. Measure the gallons of mix used. Then measure in packing cans the gallons of ice cream ob- tained and calculate the per cent, of swell. 2. Weigh one gallon of the mix. Weigh the first gallon and the last gallon of ice cream removed from the freezer and calculate the per cent, of swell in each case. 3. Take two samples, perferably from different packing cans of ice cream from the same freezer, and determine the per cent, of swell by the method given in Bulletin 241 of the Wisconsin Station as fohows: Take a 50 cc. sample of ice cream with the sampler furnished you and transfer to a 300 cc. beaker, using exactly 200 cc. of hot water to melt it. Then transfer all of this to a 250 cc. Florence flask and add 1 or 2 cc. of ether (measured) to reduce the foam. Next add enough water measured from a burette to fill the flask to the mark. The ether and water required represent the swell. Calculate the per cent, in each case. Which method do you consider the most accurate for commercial use and why? For experimental use and why? Give special advantages of each test. AN ICE CREAM LABORATORY GUIDE EXERCISE VI REPORT 27 Date Receipt Number., CREAM : Age Acidity Temperature ICE CREAM : Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk Standardize pounds of cream testing per cent fat. SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used... Pounds salt used. TIA/[E Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. X r= the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after it is hardened: 28 AN ICE CREAM LABORATORY GUIDE HARDENING ICE CREAM Ice cream may be of the highest quality when re- moved from the freezer and yet be ruined before it becomes hard enough to ship unless the hardening is properly accomplished. The two principal methods in use are the salt and ice method and the artificially cooled dry hardening room where the cans of ice cream are simply set in a very cold room and hardened by still or circulating cold air. The temperature of such a room should be maintained at near zero F. With either method the hardening process should not require more than twelve hours. The packing cans should always be cold before they are filled with ice cream, so as to prevent melting in the bottom. Directions for hardening in salt and ice. Either ordinary packing tubs or a large box may be used for this purpose. If tubs are used, simply pack well with salt and ice mixed in the proportion of one to eight. It is necessary to repack these tubs two or three times a day in order to keep the ice cream hard. When several cans of ice cream are to be hardened at a time a better method, more economical in labor and material, is to pack the empty cans up to the covers in a large box, using salt and ice, one to eight. The soft ice cream is poured into these partly packed cans and when full they are completely covered with the ice and salt mixture. With such a box it is not necessary to re- pack oftener than twice a day. 30 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER VII FREEZING FRUIT ICE CREAM— HARDEN- ING IN SALT AND ICE Freeze fruit ice creams after the following formula, using such of the flavors as are assigned. Fill out record blank on opposite page. Receipt: 40 pounds of 20% cream 8 pounds of sugar 4 ounces of gelatin in 4 pounds water 3 quarts pulped fruit Color, if desired. Flavors: Pineapple, raspberry, peach, cherry, strawberry. Either fresh or canned fruit may be used. If a perpendicular freezer is used, the fruit should not be added until the ice cream begins to thicken, which will prevent the fruit settling to the bottom of the freezer. Harden this ice cream in a salt and ice mixture. AN ICE CREAM LABORATORY GUIDE EXERCISE VII REPORT 31 Date Receipt Number. CREAM : Age Acidity Temperature ICE CREAM : Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk Standardize pounds of cream testing per cent fat. SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used... Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. X = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per ■ cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time- Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after it is hardened : 32 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER VIII NUT ICE CREAM Freeze nut ice creams as assigned, using the formula given below. Fill out the record blank on opposite page. Flavors: Walnut, fxlbert, almond and pistachio. It is better if all of these, except the walnuts, are blanched before using by scalding with boiling water and removing the skins. Prepare the nuts by running them through a meat chopper and add to the ice cream after it freezes enough to begin to thicken. Receipt: 40 pounds of 20% cream 8 pounds of sugar 2 ounces of vanilla extract 4 ounces of gelatin in 4 pounds water 3 pounds of nut meats If pistachio nuts are used, color the ice cream a pale green. AN ICE CREAM LABORATORY GUIDE 33 EXERCISE VIII REPORT Date Receipt Number. CREAM : Age :. Acidity Temperature ICE CREAM : Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk Standardize pounds of cream testing per cent fat. SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used... Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. X = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after It is hardened: 34 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER IX BISQUE ICE CREAM Freeze bisque ice cream after the base formula given below, using such of the following flavors as are as- signed. Fill out the record blank on opposite page. Flavors: Macaroons, sponge cake, grapenuts, and Nabisco wafers. Receipt: 40 pounds of 20% cream 8 pounds of sugar 3 ounces of vanilla extract 4 ounces of gelatin in 4 pounds water 5 pounds pulverized bread product. Any bread product used should be dried sufficiently so that it may be easily crushed into fine crumbs. If perpendicular freezer is used, do not add the crumbs until the ice cream freezes enough to begin to thicken. AN ICE CREAM LABORATORY GUIDE 35 EXERCISE IX REPORT Date Receipt Number. CREAM : Age Acidity Temi5erature ICE CREAM : Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk Standardize pounds of cream testing. per cent fat. SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used- Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. X = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? _ Remarks : Comments on ice cream after it is hardened: AN ICE CREAM LABORATORY GUIDE 37 EXERCISE NUMBER X MAKING BRICKS AND FANCY MOULDED ICE CREAMS Freeze the following plain ice creams as assigned. Freeze in the order given. Fill out record blank on the opposite page and make bricks and molds of the ice cream as directed below. Receipts: No. 1. 40 pounds of 20% cream 8 pounds of sugar 5 ounces of gelatin in 4 pounds water 4 ounces of vanilla extract No. 2. 40 pounds of 20% cream 8 pounds of sugar 5 ounces of gelatin in 4 pounds water 1 quart pulped strawberries 4 ounces strawberry extract Color pink No. 3. 40 pounds of 20% cream 8 pounds of sugar 5 ounces of gelatin in 4 pounds water 3 ounces of vanilla extract 1%. pounds chocolate with 4 pounds of water and one pound of sugar (cocoa may be used if desired). Fill the outside of a few center mold bricks with vanilla ice cream. Harden in a salt and ice mix- ture one part salt to two parts of ice. When hard 38 AN ICE CREAM LABORATORY GUIDE withdraw the center mold and fill with the straw- berry or chocolate ice cream. Again pack in salt and ice to harden. Fill a few fancy individual molds and pack in the salt and ice mixture till hard. Each student should make a 3 layer tri-colored brick. First prepare the molds, attach your name and pack in salt and ice to become thoroughly cold. As the vanilla ice cream is drawn from the freezer fill each mold one third full and pack in the salt and ice mixture, so that it will be hardened by the time the strawberry ice cream is ready to be drawn off. Then fill another one third with the strawberry. Finish filling with the chocolate, being sure to have the brick so full of soft cream that no brine can enter under the lid. Care should be taken each time to have the bricks set level in the salt and ice. AN ICE CREAM LABORATORY GUIDE 39 EXERCISE X REPORT Date Receipt Number CREAM: ICECREAM: Age Gallons Acidity Weight per gallon. Temperature SWELL: STANDARDIZATION: Gallons Per cent. Per cent fat in cream — — ___ Per cent fat in milk FREEZING : Standardize pounds of Freezer used cream testing per Pounds ice used... cent fat. Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. That freezing is completed ^. . Total time required to Uive proportion. freeze X = the pounds Pounds of cream used TEMPERATURE Pounds of milk used Of mix entering freezer ^^ , ^ „ Of brine when mix reaches Pounds Gallons 30° F Weight per gallon Of ice cream when'removed Per cent fat it should test Of brine at this time Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after it is hardened ; AN ICE CREAM LABORATORY GUIDE 4I EXERCISE NUMBER XI CUSTARD ICE CREAM Freeze custard ice creams after the following re- ceipts as assigned and fill out report blank on opposite page. Quantities given are for hand freezers. Receipts: No. 1. 6 quarts of milk 3 pounds of sugar 24 eggs 12 tablespoonfuls of cornstarch 6 tablespoonfuls of vanilla or to taste. Put the milk over the fire in a farina or double water boiler. Moisten the cornstarch with a little cold milk so that it can be added to milk without lumping. When the milk is hot, add the cornstarch and stir until it begins to thicken. Beat the eggs and sugar together until light and then add them to the hot milk. Cook a few minutes, take from fire, flavor and cool and freeze same as ice cream. Other flavors as coffee or chocolate may be made by substituting these flavors for the vanilla. No. 2. 5 quarts milk 1 quart 30% cream 8 eggs 2}4 pounds sugar % 6 tablespoonfuls flour I3/2 ounces of vanilla or to taste Follow directions given for No. 1. 42 AN ICE CREAM LABORATORY GUIDE No. 3. 2 quarts 30% cream 4 quarts of milk 3 pounds of sugar 1^ quarts Minute Tapioca yolks of 4 eggs 1 teaspoonful salt 4 teaspoonfuls lemon extract 2 teaspoonfuls rose extract Cook the tapioca in two quarts of milk for 10 minutes, then add the rest of the milk, the sugar and salt. Cook ten minutes longer. Remove from fire and add the egg yolks well beaten. Then add the extract, cool, and freeze. When nearly done, add the cream previously beaten to stiff froth and finish freezing. AN ICE CREAM LABORATORY GUIDE EXERCISE XI REPORT 43 Date Receipt Number.... CREAM : Age Acidity Temperature ICE CREAM : Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk. Standardize pounds of cream testing per cent fat. SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used... Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. X = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after it is hardened AN ICE CREAM LABORATORY GUIDE 45 EXERCISE NUMBER XII PARFAIT OR FRENCH ICE CREAM Freeze the following receipts as assigned and fill out report blank on opposite page. Receipts: No. 1. 40 pounds of 20% cream 10 pounds of sugar 4 ounces of vanilla extract 8 dozen eggs well beaten Beat the egg yolks till smooth, add the sugar, and beat again till it is dissolved. Beat the whites to a stifY froth and stir into the yolks and sugar. Mix all with the cream and cook in a double boiler to a temperature of 180 degrees F. for 15 minutes. Cool to 40 degrees F., add vanilla and freeze. No. 2. 40 pounds of 28% cream 10 pounds of sugar 4 ounces of vanilla extract 8 dozen eggs well beaten 2 quarts crushed strawberries Beat whole eggs together, add to the mix and freeze, or the whites may be beaten separately if desired and added after the mix is partly frozen. No. 3. 40 pounds of 25% cream 12 pounds of sugar 4 ounces of vanilla extract 4 pounds chopped walnut meats yolks of 8 dozen eggs 46 AN ICE CREAM LABORATORY GUIDE Beat the egg yolks till smooth, add the sugar and beat again. Then add to the cream and cook in double boiler to 180 degrees F. for 15 minutes. Cool, add the balance of the mix and freeze. AN ICE CREAM LABORATORY GUIDE EXERCISE XII REPORT 47 Date Receipt Number. CREAM : Age Acidity Temperature ICE CREAM : Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk Standardize pounds of cream testing per cent fat. SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used- Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. X = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after It is hardened: AN ICE CREAM LABORATORY GUIDE 49 EXERCISE NUMBER XIII PUDDINGS Freeze the following puddings as assigned and fill out report blank on opposite page. Receipts: No. 1. — Nesselrode. 32 pounds 28% cream 10 dozen eggs 10 pounds of sugar 6 ounces vanilla 4 pounds chopped walnut meats 3 pounds chopped candied cherries 3 pounds chopped candied fruits 4 pounds chopped raisins Cook the ^gg yolks with the cream. Beat the whites and add when partly frozen. No. 2 — English Plum. 32 pounds 25% cream 8 dozen eggs 12 pounds sugar 3 pounds cocoa or chocolate 5 pounds assorted fruits that do not pulp 2 pounds seeded raisins 3 pounds dates 4 pounds walnut meats 4 tablespoonfuls ground cinnamon 1 tablespoonful ginger 1 tablespoonful ground cloves Use the eggs as directed under receipt number one. Chop the fruits and nuts fine. 50 AN ICE CREAM LABORATORY GUIDE No. 3. — Fruit Pudding 32 pounds 10% cream 8 pounds whole condensed milk 8 pounds of sugar 5 ounces of gelatin dissolved in part of cream 2 pounds chopped cherries 2 pounds chopped raisins 2 pounds chopped nuts 1^ quarts sherry wine Soak the fruit over night in the sherry wine. AN ICE CREAM LABORATORY GUIDE 5 1 EXERCISE XIII REPORT Date Receipt Number. CREAM : Age Acidity Temperature ICE CREAM : Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk Standardize pounds of cream testing per cent fat. SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used- Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. X = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after It is hardened ; 52 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER XIV ICES Freeze the following water ices as assigned and fill out record blank on opposite page. Receipts: No. 1. 48 pounds of water 20 pounds of sugar 6 pounds of lemon juice No. 2. 48 pounds of water 20 pounds of sugar 2 pounds of lemon juice 4 quarts pineapple juice No. 3. 48 pounds of water 20 pounds of sugar 2 pounds of lemon juice 4 quarts finely pulped strawberries No. 4. Same as number two, except freeze very rapidly with little agitation. This is often called a granite. AN ICE CREAM LABORATORY GUIDE 53 EXERCISE XIV REPORT Date Receipt Number. CREAM : Age Acidity Temperature ICE CREAM : Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk Standardize pounds of cream testing per cent fat. SWELL : Gallons Per cent. FREEZING : Freezer used Pounds ice used- Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. X = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks ; Comments on ice cream after it is hardened 54 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER XV WATER SHERBETS Freeze the following sherbets as assigned and fill out record blank on opposite page. Receipts: No. 1. 48 pounds water 16 pounds sugar 1 pound lemon juice 4 quarts grated pineapple (or pineapple juice) 6 ounces of gelatin in 4 pounds of water, if de- sired 24 Qgg whites beaten stiff and added when mix- ture is partly frozen No. 2. Same as number one except replace the pine- apple with grape juice. No. 3. Use same mix as number one except re- place the pineapple with orange juice. Boil the water and sugar to a clear syrup, then strain and cool before freezing. AN ICE CREAM LABORATORY GUIDE 55 EXERCISE XV REPORT Date Receipt Number. CREAM : Age Acidity Temperature ICE CREAM : Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk Standardize pounds of cream testing per cent fat. SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used... Pounds salt used. TIME Of starting freezer That mix reaches 30° F. Required to reach 30° F. Give proportion. X = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE ~ Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after it is hardened : 56 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER XVI MILK SHERBETS Freeze milk sherbets after the following base for- mula, using such of the flavorings as are assigne !. Fill out the record blank on the opposite page. Flavors : Orange, grape, cherry, pineapple, and strawberry. If lemon is desired, use only two quarts of lemon juice with a quart of orange juice. Receipt: 48 pounds of milk 16 pounds of sugar 5 ounces of gelatin in 2 quarts water 1 pound lemon juice 4 quarts fruit flavoring 12 Qgg whites beaten stiff and added after mix- ture is partly frozen. AN ICE CREAM LABORATORY GUIDE Cy EXERCISE XVI REPORT P^^^ Receipt Nu mber CREAM: ICECREAM: Age Gallons ^^ature-z:::::::::; ^^'^'^^ p- ^'^- SWELL : STANDARDIZATION: Gallons Percent Per cent fat in cream — — Per cent fat in milk FREEZING- Standardize pounds of Freezer used cream testing per Pounds ice used c^"t fat. Pounds salt used TIME Of starting freezer That mix reaches 30° F.."" Required to reach 30° R That freezing is completed Give proportion. "^"freeze'™" "^^'^ "^ X =3 the pounds -^ Pounds of cream used TEMPERATURE Pounds of milk used Of mix entering freezer ^Pounds Gallons ^\^o%' ^^^" "^^" ^^^^^^^ '^s'^'Lir g^^^^-shouid ^^.^- :::^ ^^^^- Of brine at this time Was gelatin used? By method 1, 2 or 3? In milk or water? Remarks : Comments on ice cream after it is hardened : 58 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER XVII PUNCHES AND LACTO Freeze the following formulas as assigned and fill out the record blank on opposite page: Punches: No. 1. 48 pounds water 20 pounds sugar 1 pound lemon juice 1 quart brandy and rum mixed No. 2. 48 pounds water 20 pounds sugar 1 pound lemon juice 1 quart orange juice 2 quarts wine 4 ounces gelatin in part of the water No. 3. 48 pounds water 20 pounds sugar 1 quart lemon juice 1 quart raspberry juice 1 quart grape juice cloves, cinnamon, allspice and nutmeg to taste. Lacto (From Iowa Station Bulletin 140) 48 pounds good starter just nicely coagulated 18 pounds sugar 24 eggs, whites and yolks beaten separately 2 quarts of grape juice 1^ quarts lemon juice Mix in the order given in the formula. Other flavors may be substituted for the grape juice. AN ICE CREAM LABORATORY GUIDE $9 EXERCISE XVII REPORT Date Receipt Number. CREAM : Age Acidity Temperature ICE CREAAi: Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cieam Per cent fat in milk Standardize pounds of cream testing per cent fat. -<- SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used... Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. X = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should test Of brine when mix reaches 30° F Of ice cream when removed Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after it is hardened : 6o AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER XVIII MOUSSE Prepare and freeze mousse after the following formulas as assigned. No. 1. — For five gallons 20 pounds aged sweet cream, at least 40% fat 5 pounds sugar 6 ounces of gelatin juice of three lemons 3 quarts strained strawberry juice Dissolve the sugar in the fruit juice, then stir in the gelatin dissolved in a very little water. Chill this mixture but not enough to form a jelly. Whip the cold cream till stiff and then fold in the gelatin-sugar-fruit mixture. Pack into molds or cans and harden in a salt and ice mixture one to two. Other flavors may be substituted. No. 2. — For five gallons 20 pounds of aged sweet cream, 35% fat 4 pounds of sugar 5 ounces of gelatin 2^ ounces of vanilla Dissolve the gelatin and stir into the cream. Whip till stiff, then fold in the sugar and vanilla and pack in cans, hardening in salt and ice mixed one to two. Report results on opposite page. AN ICE CREAM LABORATORY GUIDE ' 6l EXERCISE XVIII REPORT (i2 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER XIX STANDARDIZE MIX TO A GIVEN PERCENT- AGE OF FAT The following materials will be furnished : cream, milk, sugar, chocolate, fruit, vanilla and gelatin. From them make up a receipt and freeze a batch of ice cream to contain a given per cent, of fat as assigned. Test the frozen ice cream for fat and report the re- sult to the instructor at time of testing. Include your receipt and all calculations and tests on opposite page. Mark plainly each can of ice cream with the receipt number, your name, and the date. No. 1. Vanilla ice cream to test 14% fat. No. 2. Vanilla ice cream to test 12% fat. No. 3. Vanilla ice cream to test 9^% fat. No. 4. Fruit ice cream to test 11% fat. No. 5, Chocolate ice cream to test 12% fat. AN ICE CREAM LABORATORY GUIDE EXERCISE XIX REPORT 63 Date Receipt Number. CREAM : Age Acidity Temperature ICE CREAM: Gallons Weight per gallon. STANDARDIZATION : Per cent fat in cream Per cent fat in milk Standardize pounds of cream testing per cent fat. SWELL: Gallons Per cent. FREEZING: Freezer used Pounds ice used... Pounds salt used. TIME Of starting freezer That mix reaches 30° F Required to reach 30° F. Give proportion. 21 = the pounds Pounds of cream used. Pounds of milk used That freezing is completed Total time required to freeze TEMPERATURE Of mix entering freezer MIX Pounds Gallons Weight per gallon Per cent fat it should Of brine when mix reaches 30° F Of ice cream when removed test. Of brine at this time. Was gelatin used? By method 1, 2 or 3?. In milk or water? Remarks : Comments on ice cream after it is hardened : 64 AN ICE CREAM LABORATORY GUIDE SCORE CARD FOR ICE CREAM The comparison of ice creams is accomplished best by reducing their quahty to a numerical basis. This is done by use of a score card. Two score cards are suggested as follows : Modification of the Cornell Score Card Wisconsin Score Card Flavor 45 Flavor 40 Body and texture 35 Body and texture 25 Richness 10 Bacterial count 15 Appearance 5 Richness 10 Package 5 Appearance 5 Package 5 100 100 It may be more advantageous to use the Cornell score card in the Laboratory because immediate results can be obtained, while with the modified Wisconsin score card bacterial counts must be made of the ice cream, so that it would be two to three days before the final score of the ice cream could be obtained. Discussion of Qualities of Ice Cream Flavor. The ice cream should have a pronounced flavor which will blend with the flavor of the cream to give a clean, desirable typical flavor. Body and Texture. The body should be firm and mellow. It should not be tough or rubbery neither soft or mushy. The texture should be smooth and velvety and entirely free from graininess and lump- iness. Richness. If the ice cream meets the legal require- ments, it should be given a perfect score. If it falls below the legal requirement, it should be scored zero. AN ICE CREAM LABORATORY GUIDE 65 Appearance. The ice cream should have an at- tractive appearance and be of the characteristic uniform color. Package. The package should be neat and clean and, if for long shipment, some provision should be made to protect the ice on top of the packing tub. Bacterial count. An ice cream which has a count of 20,000 should be considered perfect. For each in- crease of 20,000 above this one point should be de- ducted from the score. Application of score card. When judging samples of ice cream, it is best to try some of them to obtain some idea of the qualities of the samples to be scored. This is necessary so that the score will not run above 100 and to set a standard. Then with a definite stand- ard in mind, the samples may be carefully scored. The cuts in score should be made in proportion to the quality of the ice cream and the definite standard in mind. 66 AN ICE CREAM LABORATORY GUIDE EXERCISE NUMBER XX JUDGING PLAIN ICE CREAM Score and criticize the samples of plain ice cream recording the scores on the opposite page. (For score card see page 64.) One sample will first be scored by the instructor as an example and guide to the severeness of the cut for different defects. After the students have finished, he will score the remaining samples with them. Three of the samples are ice cream made in the college laboratory. The others are purchased and represent well known commercial ice creams. After scoring on all other points make a fat test of each sample. (See page 14.) AN ICE CREAM LABORATORY GUIDE 67 l/l 1 1 <& '75 mm u KM 5- » U '^ 3JB|,I ttJ • |B)O.F. aau>iOBj 3,\JB0f1ClV pUB J0|03 BIJOJOBa ssouipiy oin^xai putj Apog JOATJIJ jsquinN }dj9oaa OB "O CO T) to •o to •c to •c 6 IP 1? 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