FACTCRS AFFECTING FAT LOSSES IN ICE CREAM PROCESSING Thesis far fha Dogma of M. S. MICHIGAN STATE COLLEGE Joshua W. Kearney, Jr. I952 ,y’fi ’«o‘ -( This is to certify that the 15,-. .l' \ - n O— ‘1’ 4 ' thesis entitled Y. . .'_. ‘5 v a L “. Mggflguéz Factors Affecting Fat Losses 3a: jifi-r ' in Ice Cream.Processing qvj -' 472‘ presented by - Joshua W. Kearney I ’l . I .r a: I. ,. 3"," ‘ A“ ,. I v —' I ' J: _. ',r‘.,- u, N . . ‘A o IIA,‘ I. 4'. .-. ' . . v , :Zaéfi’fi. has been accepted towards fulfillment _ ‘ I . of the requirements for ' 3,16 . _M..S_.__degree in_fleiqt_ ‘£ ...-$ 5:11“: p r I“ at? Era-’1 1"? figs L 5* , M r . . .5‘3. 3‘ r: ”.v ~ 4.5,. r '1" h" . I ,I. ; 'u'.“' ‘5" '3‘- " "“A‘ “ “ar- JIVII.. at. H‘ ~‘ , v ‘ 1,- . 4‘ _ I J I' v - I, ,/ ~J' I r , . r'l' h ‘ f" 1.. Q I D 4 v .7 . l ', .' . -' . v -o v . r 20 7 ‘ »' 15.": .’. ' ' .- -~ , u.) . (I . . , .. . -. ..- -« - ,. w - s v ~ , ~ -‘.’l-L§l— -. I‘; .: . I _ ".5’ .v .. ~. . . ~ .I ’L‘. “a. “3‘4qu “05.17.41: a ‘.Wi€’—F fl- f’b-fi’u'flfs; *1 .. ..',— g . _!_\.‘, T" "7" “3.351..- 7.7" 4- v "l‘ . I , V: .I .I I; I.I'f 3 ,I . .. er" L :17 4:} “:1“; I; #6. JL 451'. $4,319. "VI???” ‘04?“‘é :ch‘ *: 6!? u‘ £4,“ \fi'r _Iv-;I t‘. (I :1 .V' . s . . ..‘ I . ‘. r... _ .A_ ‘s n grad ' ."I . v-wfiz’" .. ' ._¢A‘.‘¢--l‘" n” ---’. v. r. - ‘ - 7 5‘ - . s i ' - ' ‘. (5 {AJ‘ SVAJ‘”; “:- «3- .'. 71 "if 1" .~ 9‘73 " "7‘45"“ 33"” 1'23 "Ar - ’. I In .-" -. '. -I , . . :”‘. '.I .‘QI" 91‘” ' ' ,..\' “flu-”,3: ”‘57.. 5739:. ”hi-1"}: '31.‘%‘If-‘ " “’35., .‘L. ' ~ ' ' "A 5‘2" 4 )3 3‘ ,‘ ."“ ‘0 -* - I? l - : "th; T"10‘I‘I‘I .‘,"-I ‘ ‘ 5 ..'.’u A“! J» a ‘ "- un. .4 .- .. ., ‘. . - \ ~ w. n . . m; , ‘ " «A43 A A" -'- -‘ ' 2. :Ai'u‘x - “7‘ ‘= 'J' V ‘: w “v , J ‘ , r-‘ - ' -.-.-.- - w ‘.::~. ~. - , -..: , \5 'I ,- I use: .HI'I"\/.I .é- . IQ‘ 1-1.) I It...“ (‘13.), - A.) \— '3’: A: {5. . . A k V " - ‘ - ‘. lu’ : " "I ‘0'. ' ‘\ l;’.‘ b j! ‘ I’ ‘ . ;-| . H ,3 - s .'- v I .4 I . I' / . \ .b' ‘ ‘A ‘ q 4 u" u. ‘ . , II . age-fix“; 2'5". r 5-< ' ’:_ . . _ '0 ~ D - -I' - ' ~ g; _(. \' L--.\ PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before date due. MAY BE RECALLED with earlier du e date if requested. FACTORS AFFECIIie FAT LOSSES IN ICE CREAm PROCESSIKG By Joshua W. Kearney, Jr. up A THESIS Submitted to the School of Graduate Studies of richigan. State College of Agriculture and Aonlied Science in partial fulfillment of the recuirements for the degree of EASTER OF SCILJCE Deoartment of Dairy 1952 1111.123: CKHCWLEDGEEKTS The writer Wishes to express his sincere apnrec- iation to the following: Dr. Earl Weaver, Professor and Head of the Department of Dairy, for placing the facilities of the department at the writer's disposal. Dr. J. A. leiser, Assistant Professor of Dairy, under whose direction this work was done, for his help- ful suggestions and constructive criticism throughout the course of this investigation, and for his invaluable assis ence in the nreparation of this manuscript. Ii -‘_4 \("’(')I"‘)l; . . 1 ‘ r , . . . _i h:____1- TABLE OF INTRODUCTION . . . . . . . . . REVIEW OF LITERATURE . . . . . GENERAL PROCEDURE. . . . . . . Processing the Mixes . . . . Sampling and Analytical Methods. . . . . . . . . . . PLAN OF EXPERIMENT . . . . . . EXPERIMENTAL . . . . . . . . . CONTENTS Variation in the Fat Content of Ice Cream Mix Pass- ing Over the Cooler. . . . Distribution of Butterfat in Ice Cream Mix During Storage. . . . . . . . . . The Effect of Agitation on the Fat Test of the Ice Cream Mix. . . . . . . PAGE 0 o o o o o o o c o o o 1 o c o o o o o o o o o o 2 o o o c o o o c o o o o 5 o o o o o o o o o o o o 6 6 o o o o o c o o o c o o 8 o o o o o o c o o o o a 11 o o o o o o o o c o o c 11 o o o o o o o o o o o o 18 o o o o o o o o o o o o 21 The Effect of Aging the Mix on the Composition . . . 25 Analysis of Ice Cream from the Freezer as Compared to that Remaining on the Dasher. . . . . . . . . . 29 DISCUSSION . . . . . . . . . . SUZKARY AN CONCLUSIONS. . . . BIBLIOGRAPHY . . . . . . . . . LIST OF TABLES TABLE PAGE I. Variation in the Fat and Solids Content of Ice Cream Mix Passing Over the Cooler -— (Butter Mix) . . . . . . . . . . . . . . . . . . 14 II. Variation in the Fat and Solids Content of Ice Cream Mix Passing Over the Cooler -— (Cream Mix) . . . . . . . . . . . . . . . . . . 16 III. Distribution of Butterfat and Total Solids in Mix After Holding 24 Hours in Storage Tank . . . 20 IV. The Influence of Agitation Upon the Distribu— tion of Fat and Solids in the Mix. . . . . . . . 23 V. Distribution of Butterfat and Total Solids in Mix After Storage in Ten Gallon Cans . . . . . . 27 VI. Analysis of Ice Cream From the Freezer as Compared to that Remaining on the Dasher . . . . 30 INTRODUCTION Formerly ice cream was considered a confection rather than a staple article of our diet, but recently for many people ice cream has become a regular item of their daily diet. Consequently, the manufacture and sale of ice cream must be controlled as rigidly as milk. Most states and pro— gressive municipalities have set up standards and regula— tions that insure the consumer a safe and wholesome ice cream. These standards and regulations are closely patterned after those which have successfully improved the quality of milk. Ice cream standards as enacted in most statutes speci- fy a minimum percentage of butterfat for all flavors. In many instances it is desirable to exceed these values by as much as three or four per cent, thus composition control from a legal standpoint is not a problem. However, the greatest percentage of this Nation's ice cream volume is placed on the market possessing a butterfat content that meets or slightly exceeds these minimum standards. It is exceedingly possible that marginal values such as these may sometimes fall below the legal standards. Although these violations may be unin— tentional, the product if discovered by enforcing agencies must be confiscated and prOper legal action taken. Thus, to avoid unfavorable publicity and to maintain one's reputation, it is essential that manufacturers understand how processing procedures may give rise to compositional control problems. REVIEW OF LITERATURE Although many articles have been published relative to the analysis of ice cream, out of this numerous list only a few publications located to date deal with the effect of processing or handling practices on the fat content of the mix or of the frozen product. MacBride (1925), investigating the Mojonnier testing of ice cream, called attention to the fact that the Mojonnier method for ice cream analysis gave a lower fat test with the frozen product than it did with the ice cream mix. The differences which he noted ranged from 0.1 to 0.6 per cent. The cause of these differences was thought to be churning in the freezer. The differences themselves were eliminated by placing a quantity of ice cream, in the frozen condition, into tared stoppered Mojonnier fat extraction flasks, allow— ing it to attain room temperature prior to weighing. Crowe (1930), investigating the testing of ice cream for hutterfat, stated that ice cream when once frozen churns extremely easy when the sample is mixed for analysis. He further stated that the ice cream must be melted below 27° c. to prevent melting of the fat and that the fat must not be churned before testing for the fat content. Bird and Johnson (1931) studied the effect of process— ing, handling and testing procedures on the fat content of ice cream. They compared the fat content of ten mixes and the finished ice cream made from these mixes. The experiment is summarized as follows: Samples of ice cream mixes were taken from the holding vat after homogenization, whereas frozen ice cream was ob- tained at the time batches were pulled from the freezer. Representative samples of retail material were obtained with a dipper from the packer when it was from one—third to two- thirds full. When ice cream was sampled in the frozen condition, the fat tests agreed within 0.20 per cent or less with the analyses of the mixes, however the tests made on ice cream sampled in the frozen condition were lower in all cases than the mix analyses. No churning in the freezer was indicated when the mix, the ice cream, and the scrapings from the freezer wall and dasher were analyzed. Johnson and Ormond (1937), in studying some of the factors influencing the fat content of ice cream mix and the corresponding finished product,found that excessive shaking of melting ice cream samples used for analysis caused fat separation which produced erratic variations in the tests With a tendency toward low results. The variations ranged from 0.05 per cent fat to as high as 0.50 per cent with an average of about 0.20 per cent. Also, vigorous agitation of the ice cream mix in the holding tank caused a concentration of fat and solids in the top layer of the mix and a reduc- tion in the lower layer. Therefore, the accumulated foam layer had to be stirred into the ice cream and the agitation stopped just before drawing the mix to the freezer. They further concluded that condensation of moisture in the standardized ice cream mix and in the ice cream during freez— ing caused a fat reduction especially when the relative humidity was high, and when the frozen ice cream was de- livered from the freezers to metal hoppers. Finally, the adding of color and flavor at the freezer caused a definite loss which could be calculated. GENERAL PROCEDURE The ice cream mix used in this study was prepared under commercial conditions in the Michigan State College Creamery. The composition of the mix was as follows: 12 per cent milk fat; 10.9 per cent milk solids-not-fat; 15 per cent sugar and 0.30 per cent gelatin. The ingredients used in compounding the mixes were as follows: 1,fl87.5 pounds of 518.0 13%.0 270.0 73.0 86.0 7.8 3.5% milk 50% cream skim milk powder cane sugar corn sugar Sweetose gelatin With but one exception, the above ingredients were used throughout the study. The exception was a butter mix compounded as follows: 135.00 pounds of butter 087.25 135.00 2.00 538.50 fl skim milk powder sugar " Dricoid " water Processing Egg miggg. The mixes were prepared in 2,600 pound quantities and pasteurized at 160°F for thirty minutes into a 300 gallon Creamery Package Series B Steam Vapor pas- teurizing vat. At the end of the pasteurization period, the mixes were homogenized in a Cherry Burrell Superhomo Homegen— izer Model A 3500. The pressures used in homogenizing the mixes were 2,000 pounds per square inch on the first stage and 700 pounds per square inch on the second stage. Follow- ing homogenization, the mixes were cooled in a Creamery Package, plate type, heat exchanger. Immediately after cooling, the mixes were stored into a Pfaudler 600 gallon storage tank and held at 40°F. Following aging, at 40°F for 24 hours, the mixes were removed from the storage tank and frozen in a 40 quart Cream- ery Package Fort Atkinson Direct Expansion Ice Cream Freezer. The mixes were frozen until the Draw-rite Controller read 6 amperes, at which time the ammonia was shut off. The temper— ature of the ice cream at this point was approximately 23.5° F. The ice cream was permitted to whip until an overrun of 90 percent was reached. At this point, the ice cream was drawn from the freezer and placed in the hardening room at —10°F. Sampling and Analytical method. Samples of the ice cream mix were taken directly from the flow of mix as the product 7 passed over the cooler during the processing. Samples from the storage tank were taken from the top of the tank with a long handle dipper and those from the bottom were taken from the outlet valve. The ice cream samples were taken as the ice cream came from the batch freezer. All samples were collected in half pint milk bottles, sealed with sanitary caps and stored at 40°F until analyzed. All analyses were made at room temperature. To insure proper mixing, the bottles containing the samples were ro- tated gently. Precautions were taken to agitate the samples as little as possible to prevent the churning of the samples. Five gram samples were immediately taken after mixing in lots of four by means of the Mojonnier 5 ml. pipettes. The pip- ettes were inserted to approximately one~third the depth of the liquid and the required amount drawn into the pipette. Following the procedures outlined by hojonnier and Troy (1922), the samples were tested for fat and total solids. PLAN OF EXPERIMENT For a number of years there has been a belief among ice cream manufacturers that ice cream always tests lower in fat than the mix from which it was made. It was thought that the freezing operation caused a shrinkage in the fat content. From the previous assumption, there was a need for knowledge concerning the difference in fat between the ice cream mix and the finished product. A review of the litera— ture disclosed only limited information regarding the varia- tion in fat of the ice cream mix and the ice cream. host of the available information had to do with testing of the ice cream for butterfat. It was the purpose of this study to determine, if possible, the causes of any irregularities in the fat con— tent which might result from processing and handling of the mix and of the frozen ice cream. Thus, this investigation was limited to the study of processing methods and their ef— fect on the composition of the finished product. The mix used throughout the study was prepared according to the same formula, thereby eliminating any influence which may be at— tributed to change in the mix composition. The nature of this study was divided into sections. Consequently, each section was devoted to determining the butterfat and total solids in ice cream at various stages of processing as follows: I. Variation in the fat content of the ice cream mix passing over the cooler. Samples of the ice cream mix were taken as follows: A. The first mix over the cooler. B. When one—half of the mix was over the cooler. C. When two-thirds of the mix was over the cooler. D. The last mix over the cooler. II. Distribution of butterfat in ice cream mix during storage. For this experiment, the storage tank was used. Samples were taken from the top and bottom of the storage tank as follows: A. From the top of the tank prior to agitation. B. From the bottom of the tank prior to agitation. C. From both the top and bottom of the tank follow— ing thirty minutes agitation. III. The effect of agitation on the fat test of the mix. For this eXperiment the storage tank was used. Samples were taken from the top and bottom of the storage tank as follows: A. Prior to agitation. B. Following two minutes agitation. C. Following five minutes agitation. EXPERIEVNTAL Variation in.th§_£a§ content g; ice cream mix passing eve; jhg egole . In order to ascertain what reasonable variation might occur in the analyses of mix taken at different points in the manufacturing procedure, the mix was analyzed for fat and total solids as the product passed over the cooler. The samples were taken off the cooler as follows: Of the first mix out of the pasteurizing vat; after one—half of the mix was out of the vat; after two—thirds of the mix was out of the pasteurizing vat; and of the last mix out of the pasteur— izing vat. The samples were tested for percentage of butter— fat and total solids as previously described. The ice cream mixes analyzed were compounded from cream and butter as the source of milk fat. Cream is used primarily because it is the best source from which to secure concentrated milk fat. However, when cream is not available, the milk fat may be secured from butter or butter oil. The materials used and the formula adopted vary with the indi- vidual manufacturer; consequently, both cream and butter mixes were analyzed. The data presented in Tables I and II indicated that ice cream mix was not a homogeneous mixture as it passed over the cooler. The percentage of butterfat in the mix coming from the pasteurizing vat was in an ascending order 10 D. Following ten minutes agitation. E. Following twenty minutes agitation. IV. The effect of aging the mix on the composition. For this experiment three cans of mix (ten gallons each) were set in the ante-room of the ice cream hardening room. The cans of mix were tested after one, two and five days as follows: A. The top of the can. B. After pouring off the top five gallons of mix. 0. The combined contents of the can. V. Analysis of ice cream from the freezer as compared to that remaining on the dasher. For this experiment, the batch freezer was used. Ice cream samples were taken from the first and fifth batches of ice cream as follows: A. From the ice cream coming from the freezer. B. From scraping off the dasher. 12 with the first mix from the vat testing lowest and the last mix testing highest. Butter mixes, Which are the most diffi- cult to process, exhibited the greatest variation in butterfat content. Evidently there was a concentration of liquid butterfat on the top of the mix during pasteurization. This fat layer remained at the top of the mix even though the agitator of the pasteurizing vat was running. Since the ice cream mix passed from the bottom of the vat through the homOgenizer over the cooler, the first mix to reach the cooler would possess the lowest percentage of butterfat. The largest variation in fat was observed when the butter mixes were processed. The solids—not-fat content varied inversely to the fat with the exception of the first mix over the cooler. These data indicated that the solids-not—fat were concentrated in the middle section of the pasteurizing vat. The possible ex- planation of this may be attributed to the mix ingredients, since a portion of the milk solids—not-fat was supplied by roller process skim milk powder containing 97 per cent milk solids. The mixing of liquids, or liquids and powder, so that the end product is homogeneous presents a problem. The ice cream manufacturers attempt to overcome this obstacle by the use of an agitator. Since the force of an agitator is not always great enough to force sufficient solids to the top of the vat for a uniform distribution throughout, a low 13 percentage of solids-not-fat may exist at the top of the pasteurizing vat. The explanation for the decreased solids-not-fat in the bottom of the tank may be attributed to the position and force of the agitator. The agitator blades are located near the floor of the pasteurizing vat. The sweep of the agitator blades forces the solids upward, but not completely to the top of the vat. Therefore, a low percentage of solids is found at the bottom of the vat. Though, the agitator has done much to aid the ice cream manufacturers in their efforts to secure a homogeneous mix, it must be concluded that in- corporation problems still exist. in nnnnnnuuunuuunnuuunnuununnunuuunnnununnuwmammoaam Baa comma oHdemm cademm .Hmaooo Hobo HHS pmufim mo pmmv eonm Cowpmdnmbo I! ~:.H+ No.ma mo.ma 41. mo.ma No.ma Hmaooo wmso was pass .>H A mm.a+ mm.HH mm.HH mm.HH Nm.HH Hmaooo Hose was no M\m .HHH mm.o+ m:.HH os.HH a:.HH ::.HH wmaooo Ho>o aha mo m\a .HH om.oa om.oa om.oa mm.oa Hmaooo “use was panda .H hm fi numb mm HOME. .02 soapmaswbe owmno>4 cofipesasnopon opeOHHQaHB II mm.o+ H~.HH o~.HH MN.HH 0N.HH Hmaooo nm>o was swag .>H .J mm.o+ ~m.aa mm.HH No.HH mm.aa neaooo peso was we m\m .HHH '1, om.o+ mm.HH mm.HH mm.HH mm.HH wmaooo nope was no m\H .HH n, ms.HH H:.HH _ ma.aa ma.HH Hoaooo Hobo was panda .H m & new m soak .oz soapwanmba ommsm>4 soapmcasnmpmo opmofiadfina sexes oflmsmm oHaemm .H $094m 94h MHE MNBBDM EHAOOU mme mm>o wszm H qu¢8 15 .noHooo Hobo was pmnam Mo was» scam soapoandbo mm.o. am.oa m~.oa ma.oa sm.os “maooo Hobo was pass .sH wm.a+ mm.a: om.a: m~.H: mm.a: woaooo nope was go m\m .HHH mm.a+ mw.H: pm.as Hw.ae m:.az umaooo nope was so m\a .HH mo.o: ma.oa :o.o: mo.o: amaooo Hobo was panda .H a a. neasom a sons .oz soapmaum>u owmso>< aofipwcasaopon opeoaamass nexus oaasdm oaaesm .HH moaem mquom :o.o+ mm.mm mm.am mm.~m ma.~m smaooo peso was omen .>H wa.a+ ~m.mm mm.mm mm.mm ma.mm Hmaooo nmso saw no M\m .HHH Hm.a+ o~.wm mm.mm m~.mm mm.mm wmaooo nose awn mo m\a .HH ms.~m ms.~m mm.am oa.am Hmaooo peso was panda .H it; a a meadow a some . .02 v qofipmfismbe mmmaoem aofipmcfisnmpoo mpmofiaofina comma madamm madsmm {I llaIIIII, H mosdm mQHaom HHS mmaabm mmqooo Ema mmbo aszm Aemsqapaoov H egmo was pass .pH Ha.o+ ~m.ma nm.ma mm.ma mm.ma nmaooo wm>o was mo m\m .HHH mo.o+ mm.ma Hm.ma mm.ma mm.ma noaooo ws>o was ac «\H .HH ma.ma ma.ms NH.NH mH.NH uoaooo wmso was pawns .H R fi pom * Bosh .oz soapmanw>¢ mwwnopd aoflpmcflsnmpon opmoaaaana comma oaoemw oaaawm nun .HH moaam sea ll oa.or Hm.HH Hm.HH om.HH mm.aa noaooo wm>o use pass .>H nn.o+ :N.HH :N.HH mm.HH mm.sa wmaooo “see was no m\m .HHH Ho.o+ mm.HH Hw.aa m~.HH mm.HH nmaooo nope was no m\a .HH Hm.aa om.HH mm.HH om.HH Hmaooo peso was panda .H Ill a a pee a sons .02 _ acaamanm>g ommnm>4 coapwafissmpma opmoaaadne comma madamm oaaswm .H moemm Bdh RH“ mo mmaooo Mme mm>o oszm¢m NHH Hammo HOH ho sawezoo 94h mme 2H ZOHB HH mamo was pmswm mo pmmp son“ cofipmapmba jfllnIIJlf 14 :H.o+ mm.mm no.0: mm.mm mw.oa Hmaooo peso was swag .pH so.a+ m~.oa mm.oa m~.oa ww.o: Hmaooo nape was no m\m .HHH m.o+ mm.o: m:.o: m.o: mm.oa nmaooo Hose was we m\a .HH m~.mm pw.mm Hm.mm ~m.o: amaooo Ho>o was pawns .H a a meaaom.e sons .02 soapmaaw>e owmno>< soapmcasaopoa mpwoaaafine comma oadsmm V cadsmm 0 ”HM! In” %L HH muaam mnHaom _ mo.o+ om.mm mm.wm ~:.mm om.wm amaooo Hmso was pass .eH mm.a+ om.oa om.o: om.o: oa.o: Hmaooo wo>o was no m\m .HHH mm.H+ :~.mm o~.mm o~.mm mw.mm “maooo Hmso was me N\H .HH. Hm.mm m:.mm mm.mm m~.mm Hmaooo nmso was sauna .H a a menaom a scam .oz cospmfinmbe ommso>4 scavmcfisnmpoo omefiHafina comma madamm _ madamm .H 52m .838 I1 NHH mH quH quda 2’4- SH.H+ mm.o: mm.mm Hm.oa 05.0: mm.oa Ha.mn 0:.mm am.mm eoaPSaama opscaalhpsoka mm.a+ mm.H: o~.mm a m.a: :m.~: am.H: o~.mm m~.mm am.mm cospopawa opseaaueoa HH.m+ mm.aa mm.mm mm.H: om.as am.H: Hm.mm am.mm om.mm soapopama opaeasuoaaa :a.m+ mm.a: mm.mm ~m.a: mm.aa m~.Ha mm.mm ca.mm ~m.mm noapSpama opaaasuoua Hm.m+ mm.Ha Hm.mm mm.H: om.Ha am.Hs cm.mm mm.mm mm.mm eopopawauoom ,aoa Scam Soapo Emmifi a a5: seas 3:3 a so: 32.. a .aam xHE mme 2H mQHAom ho 20m: ZOHBH qu¢a onebmHMBmHn Ema Hozwbdth Ema 25 _1_§ effect 9;.gggpg Egg m;§,gg the compogitiop. There is a common practice among ice cream manufacturers to store ice cream mix in cans. This experiment was carried out to see if can storage of ice cream mix has any effect on the mix composition. For these data, three-ten gallon cans contain— ing mix were placed in storage at hOOF. for prescribed per— iods. The samples for analysis were obtained following one, two, and five day holding periods. The samples were taken as follows: from the top of the can; then the top five gal— lons of mix were poured off and samples were taken from the bottom half of the mix remaining in the can; then, the two halves were combined and a sample taken. An examination of results in Table IV indicates that fat separation had occurred within the cans up to the second day of storage. Following the second day, there was little or no change in the mix composition. The percentage of fat taken from the can after one day storage averaged 12.51 per cent for the top, 11.S4 per cent after removal of the top half, and 11.92 per cent for the combined contents of the can. The difference in percentage between the top and com- bined contents of the can was 0.59 per cent, whereas the com— bined contents of the can differed from the mid-point of the can by a minus 0.07 per cent. Samples from the can after two and five days storage showed the same variation, 0.51 per cent for the top of the can and 0.14 per cent successively 26 from the combined contents of the can. As the storage period increased, the solids from the top of the can decreased; whereas the solids from the mid— point of the can increased for the first day, decreased for the second day and increased for the fifth day. The data presented indicates that there is a separa— tion of ice cream mix when stored in cans prior to freezing. The separation reaches its peak following two days storage, after which there is practically no change. The solids of the mix seem to decrease from the top of the can and increase at the mid—point. TABLE V DISTRIBUTION OF BUTTERFAT IN XIX AFTER STORAGE IN TEN GALLOR OAKS 27 Sampled After Triplicate Determination Average *Variation1 1 Day % Fat % % Top 12.53 12.49 12.50 12.51 +0.59 After Removal of Top Half 11.87 11.80 11.85 11.84 —0.07 Combined . Content of Can 11.99 12.01 11.97 11.92 t“ Sampled After Triplicate Determination Average *Variation 2 Days % Fat 0 % JJ Top 12.u9 12.50 12.50 12.50 +0.51 After Removal of Top Half 11.85 11.87 11.83 11.85 —0.14 Combined ’ Content of Can 12.00 11.98 11.99 11.99 Sampled After Triplicate Determination Average *Variation 5 Days % Fat % % Top 12.87 12.u4 12.47 12.n6 +0.51 After Removal g of Top Half 11.83 11.81 11.80 11.81 -O.1u Combined Content of Can 11.94 11.97 11-95 11-95 1 Wm .____:— * . Variation from test of comb1ned can contents. IN MIX AFTER STORAGE IN TEN GALLON CANS TABLE V (Continued) DISTRIBUTIOE OF TOTAL SOLIDS 28 Sampled After Triplicate Determination Average I"Variation 1 Day % Solids a Top 38.55 38.52 38.48 38.52 +1.30 After Removal of Top Half 39.29 39.37 39.41 39.35 -0.47 Combined - Content of Can 39.87 39.9 39.88 39.82 .3d Sampled After Triplicate Determination Average *Variation 2 Days % Solids p % Top 38.59 38.64 38.72 38.65 —1.22 After Removal of Top Half 39.54 39.49 39.55 39.53 -0.34 Combined Contents of Ca 39.84 39.81 39.80 39.87 Sampled After Triplicate Determination Average *Variation 5 Days % Solids % Top 38.64 38.78 38.69 38.70 —1.08 After Removal of Too Half 39.0 39.13 39.21 39.11 -O.67 Combined Contents of Can 39.72 39.84 39.78 39.78 *Variation from test of combined can contents. 29 Analysis pf _i_g_e_ my; £93 £113 freezer pg compared Lg 3135 remaining pg 3h; dasher. This experiment was designed to determine if there is a building up of fat on the dasher as the freezing process continues. For these data, samples were collected from the first and fifth batches of the ice cream as the ice cream came from the freezer. Samples were also collected from the dasher at the end of the first and fifth run. The results of this eXperiment are reported in Table VI. An examination of the results in Table VI revealed a lowering Of the fat content of frozen ice cream as success- ive batches are drawn from the freezer. This is offset by a continued building up of the fat around the dasher as the freezing process continues. From the data obtained, the average percentage of fat for the first batch, both the frozen ice cream and the scraping from the dasher was 12.01 per cent; whereas the samples collected from the fifth batch showed an average percentage of fat of 11.98 per cent for the frozen ice cream and 12.05 per cent for the scraping from the dasher, a difference of .04 per cent which indicates that the fat builds up around the dasher as the freezing pro- cess continues. TABLE VI ANALYSIS OF ICE CREAM FROT THE FREEZER AS COAPARED TO THAT REEAINIEG ON THE DASHER 3O Samgéecgzggen % Fat Aveiage Variation First Batch 12.0 12.03 12.01 12.01 Fifth Satoh 11.98 11.97 11.99 11.98 +0.03 1 SCRAPING FROM DASHER First Batch 12.01 12.01 12.03 12.01 Fifth Batch 12.03 12.05 12.06 12.05 +0.04 Sample Frozen % Solids Average Variation Ice Cream m p First Batch 39.64 39.61 39.67 39.64 __rifth Batch 39.65 39.62 39.69 39.65 +0.01 First Batch SCRAPIhG Fans DASHER' 39.67139.61 [39.65 l 39.64 [ Fifth Batch w 39.67[39.63 B85 I39.65 ] j +0.01‘JJ DISCUSSION Since the percentage of butterfat in frozen ice cream is lower than that of the original mix, it indicates a loss of butterfat during the processing procedure. This experi— ment was designed to determine at what step or steps this loss occurred. Analysis of mix coming from the pasteurization vat through the homogenizer indicated that ice cream mix is far from being a uniform mixture. The butterfat content varied from a low of 0.10 per cent for a cream mix to a high of 1.47 per cent for a butter mix. The total solids content varied inversely to the fat with the exception of the first mix over the cooler. Secondly, the distribution of butterfat in the storage tank was not uniform. Analysis of results in Table III indi- cated that a separation of butterfat occurred after holding the mix for twenty—four hours in the storage tank. The dif- ference between the samples taken from the top and bottom of the storage tank was in one instance as high as 1.53 per cent. Further, the results indicated that the total solids tend to settle to the bottom of the storage tank upon storage for twenty—four hours. The difference between the samples taken from the top and bottom of the storage tank was 2.27 per cent. 32 The use of cans as a method of storage for ice cream mix indicated a fat separation taking place within the cans. The results in Table IV indicated that this separation reached its peak at the end of the second day of storage. The difference in percentage of fat of samples taken from the top of the can and mid-point of the same can as compared to the combined contents of the can was 0.59 and minus 0.07 per cent respectively, for the first day of storage; whereas the samples taken the second and fifth days from the top and mid—point exhibited an 0.51 per cent and minus 0.14 per cent from the combined contents of the can. The solids at the top of the can tend to vary inversely with the storage period from the combined contents of the can; whereas the solids at the mid-point of the can tend to increase. Agitation to insure uniformity of the mix held in vats or cans is essential. Samples were collected from the top and bottom of the storage tank after zero, two, five, ten, twenty and thirty minutes agitation. The results in Table V indicate that the percentage of butterfat at the top of the tank decreased inversely with the agitation; whereas at the bottom of the tank the percentage of fat increased with the time of agitation. After thirty minutes agitation, the vari- ation in percentage of fat between the top and bottom of the tank was less than 0.01 per cent. The solids increased at the bottom of the tank with the time of agitation, until at 33 the end of thirty minutes agitation, the difference between the top and bottom of the tank was 0.02 per cent. The final tests indicated a building up of fat on the dasher as the freezing process continued and a corresponding reduction in the fat content of the finished ice cream. The average percentage of fat in the frozen ice cream from the first batch was 12.01 per cent and for the fifth batch 11.98 per cent, a difference of 0.03 per cent. The samples from the scraping of the dasher averaged for the first batch 12.01 per cent, and for the fifth batch the average was 12.05 per cent, a difference of 0.04 per cent. Results of tests on the frozen ice cream and scrapings from the dasher indicated that there is a definite separation of fat within the freezer, and the separated fat concentrates around the dasher. The increased percentage of fat around the dasher accounts for the difference in the fat test be— tween the mix and the frozen ice cream. If the ice cream mix is thoroughly agitated for at least thirty minutes before freezing to insure a uniform composition; the the lowered percentage of fat in the frozen ice cream is due to the sepa— ration of fat in the freezer. The separated fat concentrates around the dasher and is removed when the dasher is washed. The fat loss then is in the wash water used to clean the freezer after use. In preparation of ice cream mixes, the ingredients 34 should be combined in the pasteurizing vat and heated until all of the ingredients are completely suspended and thoroughly mixed. Following pasteurization, homogenizing and cooling, the mix must be collected in a storage vat and thoroughly mixed prior to freezing. Canning directly from the cooler is to be discouraged since considerable variations in the compo- sition of mix as it passes over the cooler has been shown. Should mix be held for indefinite periods, it must be agitated prior to drawing the mix into the freezer, whether stored in cans or tanks, for approximately thirty minutes to insure complete uniformity. There is, however, a limited extent of agitation, since it is possible to over-agitate, thus causing the mix to churn. If this occurs, the previous processing operations are rendered ineffective. When stand— ardizing ice cream mixes to meet the minimum legal standards for butterfat, an extra 0.2 to 0.3 per cent of butterfat must be added in order that the percentage of butterfat of the frozen ice cream will be within legal limits. The ad- dition of butterfat insures the ice cream manufacturers against losses due to churning in the freezer. SUMMARY AND COXCLUSIONS 1. Ice cream mix is not a homogeneous mixture as it passes over the cooler. The butterfat passes over in an ascending order, while the solids are inverse of the fat with the ex— ception of the first mix over the cooler. 2. Mixes compounded using butter exhibited greater compo- sitional variation than those utilizing cream. 3. Separation of fat occurs during storage of the mix; the fat concentrates at the top of the mix whereas solids concen— trate at the bottom of the mix, this separation reaching its peak after two days storage. 4. Agitation is essential to obtain a homogeneous mixture. The ice cream mix must be agitated whether stored in cans or storage tanks for approximately thirty minutes prior to freezing. 5. As the freezing process continues, there is a build up of butterfat around the dasher and remains in the freezer when the bulk of the ice cream is drawn from the freezer. 6. Mixes must exceed the minimum butterfat standard by 0.2 to 0.3 per cent in order that the frozen product will be within legal limits. 1. 2. 7. BIBLIOGRAPHY Bird, E. W. and E. A. Johnson 1931 The effect of processing, handling and of testing procedures on the fat content of ice cream. Iowa Agr. EXpt. Sta., Bul. 287. Crowe, L. K. 1930 Testing ice cream for butterfat. Neb. Agr. EXpt. Sta. Bul. 246. Fisher, R. C. and Charles C. Walts 1925 A comparative study of methods for determin- ing the per cent of butterfat in dairy products. I. Ice Cream. Jour. Dairy Sci. 8: 54—60. Johnson, J. J. and J. I. 0rmond 1937 Some factors influencing fat content in ice cream and the corresponding finished ice cream as determined by the hojonnier Nethod. Jour. Dairy Sci., 20: 159-154._ Maack, A. c. and P. H. Tracy I " 1940 A method for the accurate sampling of ice cream. Jour. Milk Technology. 3: 123-125. MacBride, C. S. 1925 A detail in Mojonnier testing of ice_cream. Intern. Assn. Dairy Milk Inspectors Ann. Rept. 14: 177-178. Mojonnier, T. and H. 0. Troy 1925 The Technical Control of Dairy Products. 2nd Ed. Published by Mojonnier Brothers Co., Chicago, Illinois ROOM "(I ONLY -,‘ X “- t ‘ v n . _ ~' ~ ., sq. ”film - -,_a p V) d c ' V . A' A . ‘ * 3. I 3'. .- 1". - :.‘q' I “ 3‘ 'u A - -1»- -' - _-.,..-_M—H’ I MICHI I II I IIIIIIIIIII 3 1293 01763 0207