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I " ‘-p‘ N, 1‘ .fi; .1”. I 44 . ' Na 1‘--"~‘- ‘ .1 (gm-"0 ' . ' \ ‘ TI ‘1 4a.. imp '0' .. l '3; _‘,‘v-" 07,0 '1" .. . ~ .1 ' .' v ’ ..4 V .. ._ _ _ ‘ ' ." ’. - H .A ,W. 50- - ‘ 4 ' ‘ - ‘ II > ' ..a_\-‘ .0 . I. a ' ' ‘ '4 -' - - ,J“ ‘ . - , \ ~w , ‘. . 3 V .. " t . ‘.' '. . . .' :v‘: _ ‘. 1 } )‘jfi' -.. V ‘4‘?) 2'... ‘ ‘ x. -‘."'.‘M-‘.I A ~ . ‘ ‘ V , 4 ‘ I . ‘ . ' .< ‘ 0‘. .4 . . ' ' ~ - M n . . .— .4 v . ' p _I . . ‘ _ “. "“ JL M , ' V7 ‘3» ~74.- ‘ K. «:‘ré-aém .’ _ . ‘aft‘v "a ”—w, . l’ “'0‘ v”. ..gy ~. -._._’.‘.. Av - V ' .-.‘ — ‘ V i ' - ‘ I _-.-"{.'11\‘ r- ' '. . . ' .‘ _ ' _-..:$‘ 4‘ ‘3‘. ' ' ' ' '.’.’4"3‘}'€71'b;“v‘?’-t \ 4",_.,'..,‘:‘(:‘ - ' ' .‘_ - : -: .".'_ ’ ' ' ‘_ .' -_ . k \ . ‘ ..t. ‘ \ l 'A.. ,- I. .' ‘U. " ‘f' it}? .‘hg'ar A STUDY OF ma EFFECTS OF SEVERAL FACTORS ON THE SEPARATION OF SKIM MILK mom BOTTLED 012T? R 9 I A STUDY OF THE EFFECTS OF SEVERAL FACTORS ON THE SEPARATION OF SKIN MILK FROM BOTTLED CRT; :11 Thesis Reapectfully submitted to the Graduate School of M1chigan.8tete College of Agriculture and Applied Science in.partial fulfillment of the requirements for the degree of master of Science. By John Curtis mcCan 1951 THESIS . ACKNO'XLEDGIEHI‘S The writer wishes to express his sincere appreciation to G. MEI- colm Trout, Assistant Professor of Dairy manufactures, for his kindly guidance and help in carrying out this work and for his aid and criti- cisms in the preparation of this mamscript. The writer is also greatly indebted to E. L. Anthony} Professor of Dairy Husbandry, and to P. S. Lucas,.Associate Professor of Dairy manufactures, for their aid in making this work possible. 1023408 TABLE OF CONTENTS INTRODUCTION REVIE?’ 0? LI TrllfiTURE A Discussion of Results Obtained in Studying Cream Rising in Milk. Effect of; 1. 2. 3o 4. 5. 6o 70 8o 9. Separation, clarification and agitation Pasteurization Standardization Method of cooling Temperature of creaming Viscolization Addition of salts Addition of gelatin Addition of milk solids 13 Theoretical Aspects of Cream Rising 1. 2. 3. 4. 5o 6. 7. Fibrin theory Fat clumping Adsorption Relation of various components Relation of viscosity Theory of viscolization Miscellaneous considerations EXPEREEHTAL WORK A Purpose of Experiment page 11 12 13 14 15 16 17 17 17 18 21 27 29 30 55 57 37 page 3 Plan of Experimental Work 39 1. Source of Milk Supply 39 2. Processing 39 a. Separation 39 b. Pasteurization 40 c. Cooling 40 d. Standardization 41 e. Agitation 41 f. Viscolization 41 3. Addition of gelatin 41 11. Addition of salts 42 1. Addition of condensed milk, milk powder and casein 42 3. Method of taking samples for creaming 42 k. Temperatm-e of storage and creaming 45 3.. Description of tests mde and observed 43 a. Butterfat tests 43 b. Temperature . 43 0. Observation of "creaming off" 44 d. Feathering test 45 RESULTS 46 L Factors considered: 1. Temperature of separation 46 a. Fresh milk 46 b. Stored milk 50 2. Pasteurization of milk prior to separation 52 3. 4. 5. 6. 7. 8. 9. 10. 11. Pasteurization of cream a. Raw standardized cream b. Cream from pasteurized milk High temperature pasteurization of milk versus cream used in staniardization Standardization of pasteurized cream with: 9.. Raw whole milk 1:. Pasteurized whole milk c. Skim milk from pasteurized milk Standardization a. Standardizing back 1). Standardizing with whole versus skim milk c. Temperature of standardization d. Standardizing fresh versus after storage Agitation of Cream after storage Method of cooling Temperature of creaming Time of creaming Viscolization of raw cream 8.. Temperature and pressure b. Viscolization of high test cream 0. Viscolization of only a portion of the cream 6.. Feathering of viscolized cream 12. Addition of salts page '53 55 55 55 55 59 59 59 61 64 64 68 68 72 72 72 74 75 75 78 13. Addition of gelatin 14. Addition of evaporated milk and skim milk powder 15. Addition of casein DISCUSSION CONCLUSIONS BIBLIOGRAPHY PHOTOGRAPH page 85 83 86 88 95 101 112 ”MOI It is mmhwtht, esssesslt etthe intense adver- this: end soles panties mum» .: the p... sevesel yeers, the ettentiesettheeessssssisbeisclmsnreestseretethemuy eithepredsetsshiehhebvs. heresult,leism.re crit- uel .r u. may. ..- nr. amen; n the leek or may, st the seeds um he is etfesed es the whet. manners ess distributes-s ere realism am it is 0! tb (but: of their We that seed sill est perm-est tsede reletiess ere stained sits the nine. tsetse- tsress ese, thesefese, stteqtisc te reuse te saint-nth deteets e! mummamyun. . neeeperstiesetemeretskissiuersemetthsbefleset theisttleeteseesissdeteetisthetulityeteseesefeeeseeieil- pests-es ts every silk distributes. he m ”tributes the release .tm.mnuu.mmnqpn.m1.mm.umppm esseanhidesflpereesthflex-fet,ieeveryiestetees- tent. Sines the pester preperties e: esees is ..u es tale. es some nee-.eslsiseeprestieellyellettuscrueefeseesissteslesuset by the distributes ts ”predate” u per out fittest“, eerreletien bythewettuemtettheskissinmsithmteteuhst is especially sslssireble, issues it is believed thst an testes-s ether mntwutheeseesetteettheveluetmssusluklms. ammoummumimwnmimmmm u..tmm.mm.r.m3m.rmmu.um. eetestiseseel. Insstereseeuldtem.seexpesinestslseskhesevesbeen reps-tedesthiepsetlee. m.thsseeseseweerresttheesieeeeu mmwumuum.mmnmymumu mutual-yes. lilkplestpnetieesispseeeseisceseesese is.“ 108001! W results nus-u he. W 11." m.- vith Ink efl general etssrsetiese is senseiel pleats. a... stasis, theaters. mwmuu. hlieviu tht wmmettfih, in: te verity er dispute the pseveiliss theories essesistel sith this problem would be e eestrimun te the mt milk Must”. this std: ettbefleetserseverelteetersetteetinctheeepssetienerthesfll nummnsuumnsm nu. 01 um Although as reeerd .: experiments}. sets directly “in spes e stslwetths seperstienetskissilkfreseseessesresnutn lites- eture. e sessidsretle ensst er study hes been a... both is this sentry efl ones, seletive te tn separatism of me.- from nttlel Ink. Sines m. is little differenee in tn ”tent of ere-led Wt ei'ltuttnr M fat to seliu-nt-fst ratio, tn sens asters respensitle fer fat sepesetien mm b. isvelved. A review or n. unmanned vest «.1- muons. filters nil‘eDsemd inthis M0! “M1, tar.- i'ere, to e: vein. _s_:_r_._._s 3 my}, 0151:1931“ 2!. 59.“... snow, mun..- terehuelennstretei thet e‘itetienluveriessnesshesesefteetsps the mes-.1 entities of an. silk. kilns; all Benin (9) fend Wt tn Viscosity of men could be crestly elterei t: is. “a... .r a. am: 1.. at the tin .2 up...- tiel. If tn fat was in e Deli-solid sedition, tn viscosity of tn esenfseutethsesesipeste'esisei-ilkses issrenei. lithe-ills” men name. «.11... i-siietely tennis: um ..- W1..- ties. tn resulting esee- ses les in viscosity. These verbose believe nettlesepeseterensrteiitsisflssneebyitsetteetentnsiseed misc et the tet clehles. I Munstetetthsttleseisemmtesepmtem etimrtespesetereeiserderteinsseesethewutn“. hastens inflicts" s... etserved thst violent ecitsties .r wm.mu1~ummmu.nmtm. mu. a... w the elesitieeties studies et lens: (as). ”in set Cent. (37), mus... momma. a... est 01...... (m. n... (1.), but... out wt (n). M (a). «sun‘s-i n...- (u). mm (s3). eat I. h... ..s dank... a.) st this mum am... (so) as min... (as) .9... t... emitieeties 2...... the esedsveln 5...... to ma...- sent. me. aim (s1) ..- sesteteslichtieesesee isesessliseestethsesesljestessiseidlk la elesitieeties. . manual-1mm“... (n) she-eitnttnseet fever- .u. “mam. mm. a. nan-1's...“- v.1... see we r. ..- uz... sheressnissseeee human... a... «'1. resulted 1....- esesset ereen layer. Bees (16) else etesrvet thet elesitiesties er eeu 2.. un reused m amt: slightly, est a... elesitieeties a l“. r. n... m- m: newt... Missties et ans son ..u t» Mums-immeues'r.mumuwa momummmu uwfimwmmm. mus... nan-u. an... est or... (a) «ma... a» nutty... te- tseesto a... r.ndesl:esli¢htefteet.shilet~esetueeaeve 00.1. pveeeensimetleieeseese tsetse-tel... amen-shed a... ..s m. (u) m... a... ..1. elesifiesties between If as whseeseeitnesee-velsseetesttseper eentshileeleritieeties ettttett’haevesseuetiesetesesuese-helrpeseest. ”is use...» (an ..m..n¢s.e..n... hmnl'ln ”aura”... , . . \ C y e u u H . . . . I . a. , \ . I‘ a . o . . . t .J A . . . I _ . , I \A I t l .. v I d s ', l t nu'ruunwuee'r. ”museum-menu‘s numb-unann-mwuummmun‘mem guano-nun. no: manna their runes mun-e an .111: home e. We: W me: eminent“ teen mt hen n- nee- 1: mm: mad he te a- mu or an emitter. M(M)miheeeuelumthete1ermeeuee 02m mdufllittnmmummamwumum mutant-netwwmmmmm aluuemmMei-emm1mmuumaumu nuns-e. . mom-eumummmutmuuunum elee ieeeived eeneuerene site-Men. mm m ee-eerhere m) . mmmtmmmkumemanmmmm'r. mmnmetmnmueelmtmnmeuee, mummmumu'r.mmmwmeuuu- m 10' eat 10' 1. he. mamn can» at» an. n». “hum-(fllwmtmmuuuuunomew mmmeMawu-o'nmamm emu tee) mm in» mine Wat-urn us“ I. er tom eo' iu"ee'r.amemtmummuunmmnm 53mm ‘mu m 115' eel 135' the m mpg no man; We, there}: reaming” er the leee he fie Menus. mm~nuuce’mm,mmuu—eo'wmm mamumem‘m. muwttmuauu nu emu“: e um «nu running a no 1. an. um museum-hm». In ”are to ecitetien, Ihiteher, mhiheld, Bhere en! clement (6|) «about. ecitetien was the so Iinnte mung period u no“ I. met]; hee he eppreeiehle erteet en the men veluee. it teqeretu-ee umeo'uem° r. tuna-sum nun-n. mama-m (87) theetei let em: to ecitetien it: e lens period of tile. he Iilk w e pm leee a weenie: ebility, bong reletively ~11 fer-the tint tee here in me:- thet the leee muted te no te 75 per eeet. heat (“I tend thet eneuive ecitetiee et teepereteree he” no he 136' iv. an a» net-run: reieee m m ehilityo an innate. o: ecitetia‘ eell am he um centreiieter: evi- . «a; eel ee mm eel max-at (10) pointed at, thie ie prehehly en to the feilnre to eejerete the effeete or seine .111: no. the effeete e! exitetiee. mm: (:4) iieeevei'ei thet an received et m ,1.» hole. 50' Duvhtnheetetmuyte meow ne'r. pneeieeeeeee n ueeenl-‘e. mm reeeivincteqeretueeee no te ‘0' r. um» htmumllywwedn m. Ihenthe mmormnn no out 55' r. m heetinc resulted in e 4mm ieereeee in nu.- in ehility. lentil; believed. thie iniieetei thet ecitetiee ehile eeli effeetei the nee-inc ehilit: er tee eilh, ht ee but»: eel Wt (10) heee peinted at it ie prehehl: he te W etter eterece et e eeli teqeretere. Whither eel. ee-eerhere (6t) reeehei the eeeeleeiee thet the re- ueeeieceteeeeilhieu-eeeei the nee-”lune. betcha-mm insthe O" eftheeilkmeere inn-tut thenthemheret tieee it new ”Wetmuaeilkeleeheieeetei- (. Xx. Intel effect en the me- velI- ehieh theee eerhere believe ie of cen- meiel inerteeee et pleete which hettle peetehrieei eilk etter it he teen elle'ei to m Miter. eel Wt (10) eteted thet cree- leyer vole-to toning en an em: eet fer nee-inset a“ 2. were eelell: redeeed, 1: m ericieel freeh Iilh u been parietal: eeelei w e turtle: eeeler te 0' r. n: ma ter 11: heue herere was; an re-eettiu. Very elee eeelihc or the heel an: te a. m u' 1., er tepid tebeler eeelih: te (0' 1.. ton-cu h: an: a theee mm. ”tell: W the min telnet. mum e‘itetien W very elicht inereeeee in tree. value. e: .111: eterei eel mum u to“ r. an very elicht u.‘ eeeeeee a eo‘ r. leeelte with peetenrieel .111: me thet eterece. prier te eettinc~ et en teeperetu-e. we reamed men veleeee. neee eerhere euee, heeevee, tut there eee eeneiierehle verietiee ie the ”III.“ e: “in ed Int-tin eaten-int Ink. ADO-81. to M (u). when ee-lee ere W, there it null: e elight deereeee in MA amt: with e leee iietinet m.- we. _l_t_i’e_e_t g reetmieetiee Binee the peetnrieetiee preoeee he heeeee elnet eeivereell: eleptei ee e neeee er protecting the mine publie tree the eeetreetieh er eilh-herhe iieeeeee ee eell ee en eeeneeie heeee- eity. eni einee inteetigetere ere united in the eyieien thet peeteu-iee- tieh, eeeerrieieetet the eriieeryexpenree requireihyheelthiepert- lute, reieeee the nee-inc ehilit: er hilt. thie pheee er the prehlee he received e greet ieel of experimtel 0}..th C mum: and ee-lerkere (es) and thet mm; eilh to 143' r. fer so a... ma preetieellyhe-eemeee in the ma- n1:- while in eeee eeeee ee ieereeee reeulted. Peeteurieetien et w. to l“. I. fer ”Ii-flee reieeeithe ereeelqer eeeeerece er epprexintel: I per eeht. elthevzh the renlte the.“ eeneiderehle mietieh. Peeteerieetien et Max: in. r. for the eeee “. am e ieereeeei mum-e m m. 1a.: ti 41.7 per eent eith en Imm- et :1 per eeht. mu int-mourn elee mm tint m mmm in tree. «1m due to pu- teerieetieeet 14.5. to lu'r. nun-t ee as» am one otuuu heueeldlilhee amen-mne- te the M‘Mfi.1‘l11kd9008‘_ cite ee deep e ereee line hetore peeteurieetien ee deee treeh hilt. an: mm: mm thet peeteurieetioa or on nethet um: tended to re- etere ite tree-inc ehility. M'e (£4) reeulte eheeed thet ’eeteuieihc et 16' r. fer 80 limtee «aha m m ebilit: or eilk held et iee eeter taup- eteture eppi-exintel; 9 per cent. Herding (24) teen! tht the telnet of area hetihe te ieereeee Wu thin in pelteurieetion teIperetu-e rieee free 142' to 144’ I. end ee the teqeretere ghee m the iemeee bonnie- mm: (teeter, am ever 10 per cent reduction a 145°. 1»: per out a 14s“. at ennui-tel: 4.0 per eent et lit. 1‘. he etetei thet eltheuh peteeriee- tiee et 151. 3. hell reimi the me- veleee are then ea per cent, e iietieet ereee line tee um fez-nee. mm elee mm the arm e: um: nu): ma eee received a the pleat et verim teqeeetu-ee. le eheertei thet .11: received a 59° 1. or below, when heetei eeeeeterily to moc’ to it? r.. am on w mule-t. 3mm treet- mtorunnuttuumao' to 60.1. menus". at ehehcoehilo hilt recoivoi chore to. r. are e iietioct iooroeeo in crooning ehility. mm mounted thooo reeelte ee manta; thet the aunt of ore. ehicheill level» ohreeeilkiepehioteelercooxtoetepehtho ecite- tioh it ie wanted to ehilo cold. lie-er (a) foul thet peetoerioetioh reduced the oroee voluo, hot thie reaction could he um gut. can I: cerofhl toIporetere control, tilhe'erho'e (as) roeulte m:- conorcin ocniitione ehoeod eeheiiorehle terietioh‘het the creel ton-e too many reduced by patent-tattoo. new. (or) roeulte ehoe thet peetoerieetioh et no' - 143' r. to; creoeoi the a... not to e 3.311391. extent. 145' r. am e 1c )0! cent reduction, 130. I. we ehoet 8: per cent. eei 15!. pro epproxintol: o1 per cent roieetioe in cree- volue. Jodhihe eel route (81) ohoervoi mtmmmtqoumumntuuut-ntmmmm the reduction in once line. he: foul e 1.0 per cent evoreco reduction ot 14.5.5' eel o.1 per cent et 101.5“ I. ' mun on! one. (on putmtut em: et no" to 145' r. for so eieetoo eni replay oeoloi it ever e corrooe cooler. l'hie troeteent cove eteoroeee inoroeevoloeoveryiufroeitolbpor oeet. mun (:2) etetoi thet heetiec .111: et uc’ r. m' c.) eeeooi theoroeetorieoecrorepiilrtheeiethooeooorreeeilh. Iheethe Iilk eee held ooee tin et thet toqeretnro or when hoetoi to 10' " (oe' c.) or over. the creel roeo are eloel: then on peeteeriood hilt. ehile peotoerieetioe et lad. r. (‘5' c.) for e tee nineteo are ehoet the cone renlte ee uhoetoi tilt.- 10 According to lorrincton end nueeu (:1). peetoorieetion et 140' r. for on hour ante nereel crooning. Peetonrieetion et 155° r. for 1s nin- etee folloeod w eeeux to 50' r. eeve e rodnood ereee lino whicheee loco distinct end which cenld not he reodily one until crooning hed con- tinned cont eo henree nee-er end meer (88), who peetonrieod e111: in the hottle, etntod thet e m teqereture'er peetenrieetion decreneed the crooning ehility ehilo en inoroeoo in crooning ehilit: one inlneod h: e elight oxpoenre to hoot. no: need nilh received ot the college crooner: in thie meri- nonte Jerri (c) peetonrieod nilk for 80 ninntoo ot every eholo degree he- teeee 55' an" a. (1:1 to no“ r.). llo tenet thet crooning ehilit: ineroeeed iron 55. tool. 0. (181 to 141.0. I.) otter ehich there no e docreeeoe ' Dehlherc end Ierqnerdt (10) here recently nde en oxtonoire etndq ettne one-incorre'endpeetenrinednilh. mum-eerteeereee leyoro ehoved tor: elicht docroeeoe with inereeeod peetonrioetien to.- oretnreo eoeve no“ then held for so ninntoe, hnt thooo eeeeeeeee, they etete, eere eat e: apex-teen et 144' r. reeteerteettee et leo’ r. cove e docroeee or 10 per oont, hovoter, end higher tenoretnroe brought ehent It. repid decroeooo in the depth of the oroen were. neoo eorhore noodthondlktonporerilyheetodte roc'te w’ reutheir oheeheen- )loo repreeontins noral crooning. Dehlhorc end Wt further eeeeeetretee thet the reduction e: ereee uret- h: peetonrieetion ie e tine-tenporetnro releticnehip. neuter; heetinc to 150° r. m- loee then one nimto did not effect crooning. nu: hold et 140‘ r. for three . D . , e . ‘ A . -. - . . .h . o ‘ I t ' - .7 ._ . I . I . . . ‘ . . ‘ , I t _ b. 1 ' . v . . e - . k. ., . . ‘ ' Q - . . I I, . _ o . - e 0 . . \‘ . 7 ’ u ‘ e . . t ‘ I y e - , t ~ e D ” I ‘ . ! ’ . I o’ . 0' v n e_ i A , e . , _ _ 2 e .. . . l’ I l‘ . I s r ' . , . - t . e I 7‘ e ‘ 1 r O — l' u t ‘ ’ C . ‘ t > \ “ t . e I -1 A ~ I e v I ,, . . e. . I l e | e ' J . . - e » e O ,- e“ v -. .- I' 7 .. - e x ..A ‘ I n. t 4 . e u x _ e s; l . t. ,.. u _, .I e I, I ' e e _ ‘ _. H ‘ . _r r . ‘ ‘1 e I I -, . .1». 4r - ‘ I ”I u. . -. . ‘ ex,— ‘ -. ‘ v Q t u 0 y " .1 h v 4. o " 'i . - o . e I. - . e o . ‘ . I. ‘- . e. . 11 been (eve no noticoehlo dooroeeo in creel lever volue end et 150° r. the influence of hoot on crooning tee very repid during the firet so hunter end the elnoot over in 90 ninntoo. It no further ohcvn h: neutereeeenerwet thetthe Mmpertieoof tnnilhee elterod h: the tenoretnro of etorece, could he reetorod to nernl h: noting the need nilh tree 135' to no" I. eat thet peetonrieetien in- croeeed, doeroeeed. or did not ohuuo the crooning ehility of the nilh, dependincupontho hietory of the runilh. he: further etete thet re-peetoerioetien did not opprooiehl: effect the coming of nilh. £93.12! Miutun been (it) found thot Inn froeh roe creel end ehinnilheoroninedtocivo the originl perm of fot, the . lever vee ocnotineo deeper end eonetieoe ohellovor then the orieinele unincpeotonrieed ehinnilhvithrevoreenme egreetor loee inoroen- tueuutrtheeeueixmru chi-endpeetonrieod ereee. neee (17), in hie otu: of vieoolieed nilh. letor otenderdieod freoh h per oent reecreentodyeroontnilhnoin‘froehronehinnilk. meetenderd- ieod nilh ave 18.0 )or oont oreenvolnee ee oeqerod with 13.0 for the howl vhelo nil! toetinc 4 per cent. Only one triel eee roe, he'evor, no he one not etnlairg' the effect of otenierdieetione loner (It) to“ e elicht decree.” in Motility“ h rolnlt of relish; Duluth tron oeperetor clerified nilh on! eroen ’oy elloving the tie liqnide to rudireot fro-the ooperetor into the cone oenteinore mm Ii. Murdt (10) etndiod the tree-inc ehility of hill m french-nukendoreele my etete the croenvolnle ofthoro- lode-11km emltethet efthe oricinl freehlilhmvidintthelilh 12 III freeheedeernet the tint of eeperetieh. thet the ehieeiihenr tree-em ro-eined i-odietoly, end thet the ro-ndo nilkvee eot et once for oroee rieieg. then the ehie eiih eee oeolod end otorod um. eteflerdining the creel volnn nee reduced. In dotrimtel influence ofegod ohinnilheeeoveroonehyheeting the ehinnilhortn roe-do eiihteoo°r.ereheve :ereheirheerereereprierteeettingter croo- rieinge no eging of men et cold toneretnroo did not give Ini- fern reeeite. 'tnt in gonerel. it did eet eltor the veieee of the ereee leworoe he rodnood cree- leyore voro. therefore. eeeooietod vith the cold eging of the eti- hllke lheee invoetiptore eenelnded ee e roenlt of tnir vorh thet ell eteeteriieetiee of eiih ehonld he done hoforo ' )eetonrieetien to econ-e heifer. croo- vol-tee Pol-or eet inter-en (to) etete thet thee ehin eiih ie heetod to 15‘ r. for unintoeendninodvithru oreen. ee eeeeeein rite. ehereee. vhelo eiu-eettepeeteerieee et uo'r. or etete todeotro: connlotol: the croeniu ohilitre he: odd tnt r. cree- nixed with ruehilnilheilljrodnoe enernl oroenleuere mgmgmeig nlooo nine (to) fend thet eeeiieg (eiohl: reenltod in e loee love of fet in theme huh. thiturer. hrehihelt. chere. eeicieeeet (to) etetod theteuheeeiet iee teeh or invet peetoerieere fronldl. to ec' r. envodeeoor once-volt. ehiie teen-gem: ine tenhor vet peeteerieee to 110' or 1". fel- loeod h: tepid cooling holoe cc' 1. over e enrfeco cooler rooeltod in e good ereee volneee their toote eloe eheeet thet cooling eiih to e lovtoneretnreeftorpeetonrieetionpvo edoopereroenlino einoe ooolingholcedfll. ehovede-ohhottor oroenvclnno thenooolingte e t .-‘ l t L... oo' r. er eheve. whine «Downs (31) cooled em: in the vet end ever e eerreee cooler. the redeeticn ie'ereee nee vee 2.9 per cent eet 1.5 per cent reepectivolye ' I firtin ed Ocehe (87) eleo found loco leee d. to peeteerieetion chenthc eilhcee cooled ever e cerfece cooler tnnvhen cooled intn vet. nehlhorgendnrqnerdt (10) found thettn oreoeluereenrow. freeh nilh vere not erreetei'hy'teheier cooling while the ereee leyero onyeetenricednilhwere dooperwhenthepeetenrieodeilhwec taller cooled. neee lcyere were oepocielly deeper e few henre eftor cooling. me indieeted to the inveetuetere thet re- eet peetclrieed nilh ree’ende differently to teheler eeeii-c. mgmgm m”‘¢“" m '11 “”31 Mthetlowteqoretnree of crooningor etorege give deeper-erec- leyere then do higher taperetnree. hung the eerly invcetigetorc, Iiu one nith (m. Eille (1!). wing (71). hehcoch (a) (a). rive-h (4.7), end neee'ue) ell-eueed thet‘the lower the tenporetoretho eere efficien- iethe ereeeiereeeeeeereahytheeeemt offet left inthe rue-ilk. Mentor" of epprexintoly ec' I. end lower elweye cove nore efficient crooning thee higher teqereturee end the crooning efficiency doeroeeed with increeee in teqoretnre. hetor, eftor the efficiency of grevity crooning hed heoene loco incrtent bounce of the wideepreed nee of the centrifuel eepereter end the depth of the cree- line techno the ell in- nertent teeter in erec- rieing, le-er (88) noted thet ice weter towere- teree .eve hig incc-eeeeo in ereee vein-e ever thet et reoe temeretero. fin he end Iii-he (66) nice etetod thet grevity eeperetion ie hotter the I. 14 lower tn teqeretnre. Min concluded (at) thet the etorege towere- tnre for hottlod nilh ehonld he no clcee to ireceing ee peeeihle. front (dd) ehoorvod thet the neon vol. wee elidttly greeter on row nilh eeeeeeeet d0' 1. their theeet or“ r. in ice-wetorwhilo 10' r. am e uoh loco ereee vein-e. vith peeteerieee eiih. u' r. ave e (renter volnne of creentnneo. r. onto. r. pveeuchgreetor cunnt then 70' r. vhiteeereec ee-verhere (so) eterodnilhet ec' to to. r. eneet teeeereteree eheve 50' r. they tend thet the difference in fevor of the colder touporetnreeweenrenrhodintncecoofthorewnilktnnin thet of th Wind “Ike neuter; end nerqeeret no) eelceletcd the eroen venue for eech yer eeht fet et eo’ end oe° r. the lower teneretere cevedeh per cent while the higher twentnre geve only 8.0 per cent. £9325 Yiecolieetienggmggg M (u) in 1016 celled ettenticate the feet tnt'hendlk “We“. definite ereen leyer ie thrown no. nrtinend Gone (I?) were yrohehly the firct tegive definite tete ehewingtho effect onthc erecnleyer ethane-he hymn-unitedunencflehinlilke Iilhteetiudyeroenteee “meted efi the creel vieeeliced et 8500 condo )roecnre before recen- etrnctinc. hie recenctrneted conic ave e nth greetor creee vol. the the originl roe nuke Proviene to thie, theeo werhnre vieceliecd eecnle efnlhetmOpcnndeendehteinedeeroenvelueefhporoent eeeoqercdwithtn lOporeenterecnvelneeontnnnproceecedcnch "he been (it) reported thet the nnogonieetion of e portion of the eilk decreeecd the'ereee veieee et ell preeeeree het heeereeieetiee of the 15 creenelcne geve en enornne increeee in cree- volnne. troy end Int-p (to) ohteined cindler reenlte hy heugenieing tn creen end nixing with thie eiih. heter neee (in epee further etndy with viooelieod eiir heeereeieee to percenterecn end conetrnctod 4 per cont eiih or hiring withehinnilh. nelurcudedpernntnilhwithioperoontnn- hengoniecd creel. no fer-er geve 71.8 per cent croen vclnee while the letter geve 11.0 per cent. He elee donnetretod thet in ehteiniu en eheeneuy deep creen leyer, the greeter the eeeeet of croen tehcn off, the lergor will he tn velue of creel, end nice the ricnr the erecn vicoclieed the lerger tn role. of creen, elthoogh tn crocn vole-e dcee not eorroleto directly with the outlet of. fet viecolieed. been concluded tnt the fector exerting the greetect inflnenee on the volm of ereen ie not the enonnt of fet expceod to n-gonieeticn. int tn event of create in which n civen aunt of fet ie centeined. he etetod elee thet honogienieetion of whole nilh doctrcye the croen leyer entirely. letor Don (is; eteted thet neither nilh nor ereen which hed teen ho-g- enieed willflecierete e creen leyer on otendinge hell (on) ado the etetenent thet precticel experience no chewn thet in orier‘te preteee henrehieeeeiih of enffieient etehility to prevent at eeperetion, preeenree of 8500 to 8000 pcnnde per care inch ere required. _r_:_t_e_<_:_t_ 3; Addition 3; £12 neverei ettonpte heve been eete te inoroeec tn depthefthe tree-lever innilh threvghtnedditienefvericnc chen- icel ceeponnde. Selte heve genorelly been need. lehcooh (8) found thet u eddiu 0.1 per cent cenetic code, eiih tree-ea repidly end efficiently leeving only ehent one-third tn neml mount of fet in the chin nilh. weei. nehoeehyehi hueeen m) eddod line to em: in en etteept te re- etere the vieooeity to peetcerieod wilt. hie wee not cocceeefel for tn ceeein fleoenletod in tin neeee. however, by edding cene wear to thie, tnflhy developing viecepn, they roetorod the vieooeity of the peetewrioed line loner (oz) fed thetlergoe-nnteofviecegenincrceeedtn ereenleyertntil tnnelo utertelndthe eppeerutoe oferen. lie reenlte were not nnifern, however, for in eertein trielc. I‘ll enewnte of viecegcn ave hotter roenlte then lerge cneente. ten he end airhe (“I etetod thet nth elhnli eni ecid decreeee the velocity of oopere- tier with freeh eiih het in old eiir eiheii hell. very little influence. ‘ but (19) recently chewed thet the edditicn of eeln'ble eelciwn eelte to Inn: Shite hed loot me er ell of ite crooning ehility eeve no rector- etien of creening end thet when celcinn wee eddod in wtity there wee ferther loco. ceeiee eitrete produced eieiier offeote theegh eet ee «tri-etei. has. (to) (no) end neuter; end WHO) tenet eelte edded in eettioieet‘reeetitiee hindered ereee rieing. trey end there (‘5) ”wilt.“ tenth-tom with coda-hydroxide “Met 6'0. ave e to per cent crcen velnn. 3321 :5 Addition 3; eeietie Iehn'e (to) roenlte chewed thet the ed- ditien of geletin leede te e quieter crooning eei e deeyer leyor of orecneflevery coqlete eeperetionefthe fet intn creel. Mr oelleidel enhcteneee heetoned tn eeperetion of croen frcn r- nilh end rectered the crooningpcwer of oeohednilh.’1ennenend31rhe(do) elee eheerveethet nloheugutrepcentheeneidcrehlyincrceeedthc h... retion of creon free wilt. end thet gen erotic, eteroh, em geletin hed e eieiler though not we pronounced effect. 17 mg mitieeggigw have (it) reenlte enwed thet the eddltion of nor. colide in the fern of plein coulcnwed chin will on wklllihpcwder gevc he incrceee ieereeeiigetiiity either to rower Manned nuke mm e3 Wt (19) by dilwtm new I111 with dietilled weter or the eddition of chin ndlk, end eendcnecd chin nilh mood thet enngoe in corn eelid content deco not effect crec- rioixe rnonrian. mm or am none dlcngwithtn reenlto obteined frcnthe experinentel work thet no beendoneencrcenrieinghevo eonennyetthte to onleintnce re-. nlte on e eeicntific heeie. Ihile .ny of the conclnoione expleinix creel rioing free e phyoieo-chenicel etendpoint heve been drown with e eenoidereticn of e eingle fecter involved rether then expleining the phenonene on e breeder beeio, e ctndy of theoe theercticel eepecto ohcnld be telneble to em etwdcnt of thie prohlen. It hee elweye been ogreed thet the hale-ntel canoe of the rice of fet onnernlnilhtc ferne crcen leyer ie, of conree, the difference between the opecifio grevity et the fet end the plea-e. 3.1.22 232 Probebly the firot theory of creen rioing wee the fibrin theorypreoentod by nbcech (a) in 18». He noted the cluped fet glob- nlco ere believed thet eiih conteined e onhetenoe identified with blood fibrin, cepehle of opcnteneone coegnletion, the elcto of which entenglod the fet glebn‘leo ed. being heevy, prevented on efficient crooning. nb- ceoh calcined the efficiency of low temperetu'e crooning end the eddi- tion of cenotie code on the groundo thet the ceegnleticn of the fihrin, which would clnotor the fet globnlee , wee prevented. 18 9.19.335. i few yeere leter heteoek end Rneeell (t) obeerved theft at tie-pm wee ebeent in eilk Ihieh m not eroee ”new. te hich teqeret'ere peeteerieetion, whereee, ol-pinc one proeent in ndlk which hed ereeeed nomlly. hey, therefore, reverced the for-er theory rele- tive to eluterinc, etetmg thet olnminc of the fet alebeloe wee neoco- eeryinereeerieinc. hreovcrglehe(zolheeeleechoenthet nor-cl _ em: doee net eentein fibrin. may, in eteeyteg the differonoee in sepia eat elee crooning um. elee eetee thet the tee-her hed m fet clehelee often in clue, while in the letter, peeping of the fet clebIlee wee rere. Since thet tine Mlberc end Wt (10) (11). the ne- end emu (ct). leel, eeteeeh eee meen (u). me (it) (so); eat an end mm; eftor heme; opecifio eted: e: the reletien of clneteriu to oreeeriein; roeened the oenelneion thet clneterinc of the fet clobelee ie ceeentiel to men ricin‘. [nor (It). leoee end ee- worhere [at] end ten (52) here eeeoeietod ezqm'uth oreee rieinc in calcining their reeelte in proeoeein eilk end ioc cree- nine. he: end Sher, (65). outlying Btehee l. to the velocity of rieiec of the individual fet‘clobnlee, reeehed the eeneleeion thet the clobnlee rice ee elevly ee individule thet it woeld reqeiro m tieee the ordi- neryereenincperiod for thentofcrnthe ereeeleger. Iiththeeidef e eioroeeopie crooning eell theee inveetiptore ebeerved olnetere lee“ enough to eoeonnt for neml oreee ricing. Definer: end truer“ (10) m thet the int elutere of 33.1 nee-inc lilk were lute w tobe eeeneeeilyeiththe eneidedoyeehenobeervod iee one-ducal. Incec wot-here eteted thet the lee-cor elutere were econ to rice ee feet ee one inch per ninetee 19 Iehn (IO), cbecrvin: the creedn; proocce through c herieontel netteeepe; a... re- nilh eontcined fet clobelce met in lerce eel .11 neeee while in heetod nilh the individul clobnlce were quite dietinote he lercer neeee rece Itch feetor then the individul clot- elee. hhn, therefore, ececented for the differeneee in ereen rieinc cfr-endhcetednilhinthiewwe lehn (a) (so). the ne- eat can (u). eat the. (to) etetee thet meteneee‘eeeelcretin: efl inereecing eroen fornetion ouch cc celetin, trepeenth, celeb, end ecforth, increeccd the mtien of the fet clcbnleee i'reyend me (to) teen thet treetnente feverinc nee-1a; . elee inereeeed the mute; tendency, end obeerved thet wieeocen eee eediu hydroxide which cevc very doe, creen linee threw the globulec in- to extremely lei-cc clnctcrce heel-oft (I) ceueeted the inortenee of elqinc in oreen ricinc inexpleinincthettheurcrepidereeningindoeytheninehellowyene in die to the fimr globulec ei’ betterfet being tencht by the coerce: once end ewept epoch-dc, the concentretien of the ecercer clcbnloe be- eeeiu aee't eeench to heve e filtering ectiene On the other hen. Pol-er. Benin. .d Andereen (46), with the oil of the niereccepc, fennd no releticn between Mn: end fet elector- in, end therefore, roechcd the ecneleeicn thet fet cleqinc wee not on incl-tent teeter in tree. ricinc. he hey end there (“I heve pointed cet, their concluion wee notebly dne to the difficulty of finding fine in their uthed of etndye deeerdiu to rel-er end tnderecn (do), the cine of fet globelee deo to hrecd differencee hee no effect on creel fernetione met efl Mull (H. mu (4’) (50), Reid (53), M be! end nee-p (ea) ell expleined the effect of pectenrinetion on tree-1n; ee the to~tho breehing up of the fnt elnetcre. troy end there (as) eteted tut in yeetenriced nilh which eroene nor-elly the fet globelec which ere broken up by peetenrinetion ro-clm. bet the detrincntel effect on eroeningie eencodbyhoetingthenilhtothccxtont thet the globelcc do not clnq egein on cooling. my end then (an) believed thet too nnoh egiteticn while the em: ie being cooled brcehc ep the elnqc end rcenlte in poor crooning. 'hlnerney (It), Leone end ee-eerherc (at) end m-er (u) ecoonntod for the redeeticn'in ereen line on clerified .11: on due to the hreeking u of the eleeterc. khlberg end firqnerdt (ll) helimd thet thie effect of elerifieeticn et e high temperetnre in I. to heth e broeking up of the clneterc end e reduction in cine of the eriginl glehelce. le-r (I!) believed ecperetcr clerifieetion hroehe up cinetere to e greetor cxtont then crdinry clerifioetien end thet the elight decrceee a cron- line due to ogiteticn ie e rocnlt of e elight nodifieeticn in the grena- inge of the globelee. khlbcrg eul honing (t) cteted thet the eepereter enerted ite infleenoc on wieeeeity hy ite effect entho cine end gunning of the glctelce. the (51) believed thet plent cpereticnc which egitetc the em: tend to ”lit the’giemee. but only to e elight extent, end elee. eteted thet when the te-peeetu-e ie not over es’ 0. (145.4' r.) incerteineeeee cfegitetien, there ieeteuonoyto elm the fet clebueee lemr (It) held tht the breehing up of clnetere throngh egitetion wee reeyeneiblo-for the clight docroeee in ereening ehility which he ob- cervcd when re-creening nilk. froyendlherp (GI) etteqtedtoexpleinthe incroeec inereening ebility cf nilk peetenrieed et e low teeperetere obecrvcd by nee-er (or). w efl moor (28). ell 'hiteker, hchiheld, Shore en! Olenent (69% hey oheerved thetflif'nilh ie egitetcd, eepocielly et neer roen tapere- tnrc, the eleepe of fet globulce ere hrohee eeeh end theee do not reedily fernepincvonif the nilh ie cooled to e low tenperetnree 3y eerofnlly peetenrieing thie nilh end cooling repidly to e low tenporetnre the hue- clwewereesinfornedendthe nilhgevc enimrcwederennleyc’reee reenlt of peetenrieinge my, therefore, believed en incroeee in cree- wclnne on e rceelt cf peeteerieetion indicetce thet the row nilh hee been treeted in ceoh e w during or eftcr cooling co co to ’oreek ep the clone of fet globelcc or to prevent their fornticne troy end flherp (to) found thet the rete of electering of the at globelce in frcch new eilk dcpcuod upon the rete of cooling which prob- ebly canine why repid cooling increeeee the eroening ehility of nilh. m ee- inveetiutcre (cc) cenol'ded thet for e given pcrcentege of tee the depth of the ereee leyer depelie prinrily on the states-tug end condition of the int globelce, lergo, irrogeler, etehle clnetore ftrnix deep leyere while eonpeet, cpherioel, week clnctore fcrning chellow levcre. hooper creee leyere et lower tcnpcretnree ere, therefore. calcined on the heeie thet the rigidity of the clnetcre loccen with in- ereeec in teneretnro, pernitting cloeer pecking of the fet et the werner tenpcretnrcce 3 Room ion It in well known in colloidel ehenietry thet emleione ere etehilined by the edccrpticn of nteriel et the intorfeoee Since edit in en e-leicn of fet in weter eonteining vericne cnhcteneee which ere eepeble of being odecrbed, it ie believed by new invcotigetore, thet the fet glcbolee ere cnrronnded by on edeorbed nonbreno which probobly pleyc en i'ortont role in the etobility of the fet or, to be ncrc epo- cific, in ereen rieing. hole (50) eftcr reviewing the reenltc cf verione inventigetione, hoe concloded thet opecifio edecrption end hydreticn chengee et the glcbnlc-eeru interfeco enert e nrhed effect upon the retec of rice of glebelee end perhpc expleine the .rked verietione in no. nilhe with reepect to eroon rieing. Pelner (d!) etotcd thet the nore or loce pornnent dicpereion of the at man; in out: ere due npperent]: te e concentretion of the pleen ocllcide et the globnlc-pleen interfece ell thet the reletive ‘ proportion of the cclloide odeorbed - coleinn ceeeinote, lectelbuin, lute-globulin. end eolcinn phocpheto - ehonld be in proportion to thir ebility to lower mace teneion rether then in the proportion in which they occur in nilke Pelner odded thet thie property of the nilh ecllcide hoe never been neoenrcde dcoerding to Deon (ll), the cloning tendency of the fet globelee eheee there ic on ettrection between thee, which he believed, in prob- ebly beet exputnee en en intorfeciel teneion erreet eh which he on- lergee ecuwhct ee followet let end weter interfecee give rice to rel- etivcly high nut-teem teneiene othee thie free energy on be redeeed byedoeroeec inenrfeeeerooudepoeeible by ceelceoenccofthe fet glebnlcc, the globnlec would nlti-toly eeperete into e ley'er or fet eee e lcycr cf weter, bet in oil: there ere oppccix forcee which coontereot thie inter-globe.“ ettrect ion. rhe interfeciel energy ie elee "an... by the edccrpticn of enrfeoe toneion ectivc webctencec preccnt in the eilh pleene. Adcerption econrc rodncing the free energy, elthoogh thie energy ie not entirely done ewey with eincc the fet glebnlee in nor-.1 eiih tend to oalntinete ihte eiupe due to the elight ettreetioh re-in- im. lo ooelcccence tehee plecc, however, Donn etetcd, either becenec the tendency ic co greetly overconc thet it in inenffioicnt to do nerc then ettrect the globulec together, or are logieel, he believed, be- eenee the edcorbcd leyer preventc en intinte contoct of the globnloce Priegcr (it) reeched the ecncleeien thet the fet perticlce ere enr- reeheee by protein-like filne. ritee. nee-er end nert (to) concluded eftcr nuns e ethey in en ottth te detereine the netnrc’ef the en.- . corbcd leyer, thet the odcorbed leyor wee rcletcd with, if not identicel te; eeeeih. elthcngh eiieht werieticne in cheeieel propertiee indicoted e pocciblo eenteninction with cone enhewn cnbctencc. holler (to) elee believed the fet glcbnloc ere protected free eeelcccing by e protectin cent of nilh preteine. hhn (t9) eteted thet it wenld eppeer en the“ em centeine e oelleidel eeehreee. which eccenntc for the mtiee of fet globelee end thet thie nenbrene ic deetroyed by hoot. hhn (it) om lirhc (59) both believed thet the benefieiel ecticn of geletin, treaoonth-ond einiler cnbetenoee in prenoting ereon rieiru ic doe to their edeerption which pronotee the etiching together of the globnlec. m h- “ Birhe (66} believed tilt in the me of old Iilk the ed- eerbcd protein uh... caning. elthengh there wee he effect on freeh 'eiu. no fet globulec of oil: ordinerily com o clight negotive elee- trieel ehergc doc to the edccrpticn of eeltc end dieeolvod preteine (ht). Severel inventigetore heve eddcd clectrclytec to em in en etteept to pronto greetor cloning end, therefore, better crocnim throngh e ehengc in the eloctricel ehergc on the globulee. holler (75) ctetcd thet e protecting cent of protein givec the globelec en electricel eherge which con be deetroyed by the oddition of en ogent cf nnlihe ehergo or by the destruction of thie nenbrene ntcriol through eene phyeieel agency Inch on bent or frcoeing. lirhe (at) ccnclficd thet while the negnitnde of the eherge en the globelec of verione eenplcc cf nilh worded irrcgnlerly, he fcnnd no ro- lntion between thie cherge em velocity of clnnping. In e very recent ctndy of the effect of the clectricol ehergc on creon'ricing center end earth (61) feend en increeeed crcon mei- eenee Inder conditione eeneing e eeereeee in the negotive cherge en the fet. Aging, er henting to 143' 1., deereeced, while hoeting to 143' r. in- erooeed the ehrgc. Ooleinn eeltc or iron chloride decroeeed, while eediwn citretc end di-eodinn-pheephetc increeeed, the ehergc. fhoec inveetigotore expleined the increeee in vieooeity reenltiog fron oging on due to e decree-e in the electricel cherge on the fet-globulce, thee pernitting then to clncter. hbeech (8), Inner (88) end boy end aerp (t5) foul greetor croon- ing only whenflrcletivcly lei-go eunntc of e ctrong electrolyte Inch cc cedinn hydroxide wee need while Mlberg end Wt (10) pointed out thet feilnre to obtein cncceee with eeen eeeente ie probebly dne to the effiniticc cf ceverel will: eonetitnente fer the iene edded which n in- terfere with their edccrpticn on the fete nhlbcrg end manor“ (10) preccnted e theory of croon ricing in which they enplein the clnctcrix of the globnlee on due to e docrooee 25 in the electric charge due to a change in the calcium ion concentration. Locording to those investigators "The most plausible theory of the cause of the fat globules forming into clusters was.that this aggregation was caused by the presence of e maxim quantity of calcium ions, which, by importing some positive charges to the weak, negatively charged fat globules, created an electrical affinity between the globules. it warm temperatures the Brownian mvsmsnt caused by kinetic enera was consid- ered to be sufficient to hold the globules apart which would account for the better dreaming near 40° 1?. or below. Both prolonged holding at the cold temperature of 40° or pasteurization at 14.50 F. or above precipi- tated calcium as colloidal salts and hence diminished the crooning powers of tho nilk. In the former case the calcium could be redissolved by in- creased temperature, while in the latter case tho reaction was not re- vorsiblo which agreed with the observed change in crooning.” There is e difference of Opinion, however, no to whether soluble calcium is precipitated at pasteurization temperatures especially in quantities large enough to account for the affects of pasteurization on crooning. Pelmor (42) end Van Slykc end Bosworth (67) believed that the cal-- cium phosphate of milk is present as neutral di-oalcium phosphate. Palmer (42) concluded that the partial fixation of this di-calciun phosphate during heating is due to its precipitation as colloidal nono-celciun phosphate. mgee end Harvey (35) found about 26 per cent of the total onloiun oxide wen in tho diffusiblo form in fresh milk, about so pcr cent in milk pasteurized et 158° F. for so minutes, and about 15 per cent in boiled 31‘ ailk. lhs lessee in soluble calcium after heating were believed ts be d. to the forntisn sf colloidal tri-salsiu phssphats fit-oaths sslIbls di-ealci- phssphate. _ . t as work sf hp) (56), httick ad [allett (80), ad. Dell (7) is- dieated only a very slight precipitatien ef eeleiuet pasteurisatiea teqeretu-ee up te lsc' te leo' r. loan (19) believed his results led evidence against the ealciu its precipitation theory for he res-t that the additiea ef salable cal- cium salts ts milk which had lest sen er all ef its cresaisg ability ave as resteratien. calcium added, in quantity gave further less. Study with th aid of a stealing sell showed that calcium acetate and ssdiu citrate both interfered with fat clawing, the calcium salt being asst active. ”r afl. firth (61) believed that the increased viscosity falls!- iu the addition cf viseegea is due ts the decrease in the electrical churc- brovsht a... by the calciua salts is the viseesea. as results ebtaiacd by Benin: and tuber; (:7), warns with salts in ice ereae sires, also gave support to the ealeiu isa theery. bees wet-hers feend that by adding the salts befsre bet-causing, sediu salts (ssdiue citrate and di-sediua phssphate) decreased clawing while calcium lactate increased elm-pin; as a result ef the whistles preecss. retassiua exists, which renved the soluble calciu, pve mines free from clue, therefore, indicating te these investigators that tbepreseece cf calcium salts is essential in securing clusters is hencenised aims. Salts added after hengcaisatiea, hswever, produced as effect. uses investigators believed that the sodium and petaseiue 8'? salt content in the lit nde Iron 31“). dairy products varies sufficient- ly to affect the whipping properties of the air, due to their effect on cloning. Iraq and nacho (dd) also believed that there is sufficient variation in the calcinn content of ereen eeeetieee sufficiently greet to cause a oaleian canoes, which brings about feathering in henogonised eroen of lee acidity. Ihey suggest that this variation in the calcium content is probably due to feed a‘ period of lactation. donor and Brt (‘0) have also shown that the salt balanse in Idlk varies enuh to have an influence upon the heat coagulation of evaporated nilk. 3;: Relation :5 Various Osman” _t_e_ _cr_e_an_ gig rm. has been considerable evidence presented to prove that the properties chiefly in- nuencir‘creanrisiixare inherent intheplasu ratherthaninthe fat as shown by the work of sabceck (a), seal (73), Van he and airks (dd), Palmer, Boning and Anderson (dd), and nrtin and Oenbe (87). hbcsct (d) in lddt suggested, and [col (7:) in use concluded, that the physical changes in nilk and crean brought about by heat are due to the unstable character of the nitrogenous or nineral constituents. Palnor, honing and Anderson (dd) also found that the plasu phase was affected chiefly by pasteurieatien and Palaer (as) stated that the preeehee of fat glob- Ilse in shale milk actually seems te protect the tilt against the detri- nsntal effects of pasteurieatien. lahn (d9), however, stated that the effect of pasteurisation on creasing appears to be due to alteration in the fat globule groupings and net to changes in other constituents for he found, Just opposite to Pal-er, losing and Anderson's (dd) results, that if the ehieailheee separated, heated at 147‘ “or c.) and then ronined, that nornal crooning occurred. Dahlberg and hrguardt (lO) pointed out that since the action of yesteerisatieh in reducing the arena layer was, aeseriisr to ease results, due to the effect of heat on the serum, and since others have domestrated the destruction of fat clusps by heat, it is evident that the serum in turn affects fat clawing. It has been aces-ed by my that the effect of pasteurieation is dwe to the precipitation of albumin. eehs (it). however, stated that heat does not weigh the fat globules down with eeegulated albwnin. ms theeryis supportedbyfreyandsharp (“)whepeinted out that thereis not enoughalbuin present to exert this influence. Ihitaker, nor-n see Sharp (10) tabs a sinilar point of view, explaining that if the al- business eeegelateitypesteuieetiesthere wouldbo an increase rather thanadeerease invisoeeityand, further, that them-mucous in viscosity due to heat occurs below the oeuulatiu point of alb-in. It has been shown by em (as) that as oeegulctien of alternates» place at 145‘ r., but at 150', a." per cent is resssrei insoluble. she asset precipitated inst-eases with increase in temperature as 18.75 per cent is osegulated at us'. and approxiutely in per cent at leo' r. In an atteqt to doternine which constituents of the serun were de- flusntial in crean rising phesssesa. raiser, series, and inter-ea (dd) worn. with synthetic milks, oonslfiod that oalciu caseinto, aim the not proninont colloid in nilh, hinders oresn rising, that the whey colloids, lactalbuin and lasts-globulin, pro-to crean rising, and that these effects are enbanod by pasteurieaticn. hensval of sineral salts an. lactose, inalarge nonsuro, by dialysis was found to have as detri- untal effect on ereuing. these conclusions also led then to suspect that the detrimtal effect of paeteurieatien was due chiefly to the of- feet of heat on oalciun eassinate. bees workers pointed out that in tbir belief, questions involved in ores. rising do at include that of eulsicn stability for, while there my be differences between calcium oaseinte and whey proteins concerning enlsien stability, both kinds of proteins are to be considered excellent cuisine". 9.... Relation 9:: Viscosity to 93% hey inestigators have noted the effect of pasteuriaation on viscosity and sons workers have atteqted ts saplain charges in cream rising as due to changes in viscosity. Ml- berg and honing (t) in their viscosity studies of nilh ad ocean observed that the viscosityinsroceod with fat content, especially so per cent and above, that pastourisation decreased the viscosity of nilk slightly see erean greatly, and that the effect of aging on viscosity was inhibited in a large nonsuro by pasteurieation. hboock oil Russell (d) and bid (58) uintainsd that the reduction in viscosity in pasteurieatien is he to a breaking up of the fat slugs. alerwood and sssllnele'lcs) who studied the sleeping isereeaasiiee croanenoging, concluded that the increase in viscosity is attributable to a greater grouping of the fat globules with its resulting fixation of a part of the free corn. wool. (78) ad hereon afl lorris (80) have shown tht the viscosity is decreased at eriissry pasteurieaticn teaperateres. but at considerably higher teap- eraturos (vs-so' c.) the viscosity is increased. sets (d9) stated that there is he sisple relation between viscosity and rats of m. troy ad up (d5), by diluting Iilk eentaining firmlly sinned M withwaterand securisgthe senseless efcreenas intho unliluted shock sample, deunetrated the apparent lack of correlation between viscosity and crean fornticn. a) hvcrtholess, roller and duderssn (d5) stated that the viscosity of res nilk is a good index of its creasing ability ass that viscosity canbe usodasanexplanationof changes increanlayers caused by the tomerature of creasing and the concentration of plasne solids in the nilke i'hoy added, however, that viscosity is only a ninor factor in deternining the crean layers on pastouriaed nilk and that the funda- untal factors exerting their influence renin to be deter-inede Ihitahsr, Sher-an uni Sharp (70) observed that the viscosity of skin ailh was reduced on pasteurisation and, therefore, nintainsd that thebreakingupof fut slums isnot thoonlyoauseofthedecreasoin. viscosity of whole nilh. loll (50) interpreted the literature as inlieatim tht although viscosity is usually greater in cases showing increased crean vslues, there scene to be little doubt that in not cases the viscosity is a result of the msical state rather than a reason for and an explana- tion of its cause. the increased viscosity, often noticed, he believed, is due to larger aggregates brought about by favorable conditions at the interfaces. . a m 35 _1:i_seolieation semgesisec nilk er tress, been (it) stated, will not separate out a layer of cream whether the fat globules are clunpod or uncltnpod. lougenised silk or cream, diluted with skin silk or whslo nil]: yields a croaa layer, the voices of which beocnoe greater as the degree of fat clawing increases. Sulples containing an- clasped fat diluted with skin nilh, however, ave no croan more C. 31 h-sr (as) believed that the loss of cream ability of longe- hiseusiuuceetsthshresnrgepertherstasmesintent-yuan assess which, having less tendency to rise than the origin). globules, resin erenly distributed as does the extrcasly ~11 or residnl fat globules of ordinary ailke hate-n andsharp (c) and boy and flier) (cs) have observed that in heaogeniscd am the globules are set tit-yes set explainthe stability of the fat onlsieninailhenthis lackef slums Dean (17) stated that at crdinry pressures silk does not give rise ts Wises-toluene" of fat until the concentration of fat is in excess of eight per cent which egress very closely with fining's een- . clusiono (86). ’ err-tenses (to). rrey set sherp (to), set been (17) (18) here all found that riscclisaticn er hengonieation of crese'grsstiy reduced the sins of the globules and resulted in the forntion of large oluws, while Dahle and Iartis (1:). Mn (16), and ms and lbscley (cs) agreed on the seas resultcin ice orcaa sires. be greatly increased roluo of orcaa secured by diluting honge- siestsrseh with silk is one, according to been (in, to the ieesssess of packing of the very large clusters of fat globules. a possible reason that the shunt of cross in which the fat is contained is acre inst-tent than the ssent of fat, itself, in increasing the eresa release of sizes We“. silk is that hoaogcniaaticn sets up a structure along the "Vino-clups' of fat in the cross an the value of this structure dc- ieets es the 5mm. space at the ties of Mention and further, tut this structure nintain, to a certain extent, its rel-o uson di- 4“ 32 lution of the oreaa with arm]. whole or skin like Dean (ll) has found that the clwing of hoacgeniaed silk and cross is greatlyangaantod by increases is the fat content, which disagrees with the results of hrtenssu (41) who concluded there sac apparently no definite relationship between fat content and sins of slugs. firt- ensea observed a great difference in clming of different lots of cross contaiaiugthosaaepereentefbuttcrfatendhandlodinasaearlythc seas way as possible. according to noon (ch sud Dc res (it), increased pressures result in s greater dispersionand increased clustering of the fat globules, ~ which is tobc expected, althoughthcse findingsare istisugreeusut with those of Reid and Skinner (5e) and brteucen (t1). nssh (ls) heated the sill: pisses at no“ r. for 10 uiuutes, after shiohtheplssussetsrssssereresnreisniheuegsuisec. lefcundre- dueed singing which he associated with the results of other workers uaehsveshesuthst hestingtheplsssareuueeuthe fat clauses coming power of nor-l silks we» set hole (to) in their study of the :estherisr of hesegsuisee tress, hare suggested thet the single; of fat globules is s result of variation in electrical potential on the fat globules. noun (1” be- licred that if this were true, variation in hydrogen ieu concentration would cause differences in slurping but ism that increased acidity apparently had little effect end concluded, therefore , that the electrical potential on the globules had little effect. rrsoy and nuehe (to). houses, observed that an treat-cut causing the fat to elm increased featuring, s , 1 . . s. . ' . e 1 . t t v u s \ . . I . ' n‘ ' . A i -‘- . .i ‘ ' l t t s . i . 35 am finding that preheating area. and homgenising at a high tslperatnre (175° r.) rcnored ell tendencies to feather, explained this es the, part- ly at least, to the precipitation of soluble calciun salts. It was found by nhle and larnhart (18) that pasteurisation and homgeniaaticn of ice trees nine st 170 and 130° 1. resulted in lower viscosity and greatly reduced fat tin-pier es esupersi with 150' I. It was also sheus that the temperature of hongeniaaticn was nre iQortant than the teworst'ure of pasteurisation. lol- (80), however, explains that the ngnitude of forces of viscosity and interfacial tension is usually less at the hiar tenpcraturoo, and, since these are forces that auot be owercono by ho-i valuation, the degree of dispersion increases, within certain liaits, with increases in tonperature. fraoy and niche (68) also obtained greater clustering hy hangesising at 125' r. than at 145'. Dan (18) foufl. that the ratio of tin a-lmt of seru- solids to tut in the processed aixtures is a liaiting factor in fat olming and stated that there is a critical ratio above which no clming is obtained but that owing to uncontrollable and undoterainod factors this critical ratio cannot be established at a definite value. h diluting with nter, the reducing the proportion of serun to this, noun, was able to secure elm- ing in noml low fat silk. M (10) suggested the following as a partial explamtion of tho phenoaena er fat sleeping of heuegeuieei suture”. 'I‘hcn sin: er trees is heaegesiees, the err-l fat glotulee are divided into frea lo ts 100 individuals. his action creates an enoruus new sin-face area which, of nurse, represents a considerable increase of interfacial tension on! which in turn creates an increased attraction between globules and a la grcat activity in the adsorption of the surface active plum colloids. If the fat content of the product Weed is low, tho dividod'glob- also will be relatively far apart and before any noticeable aanunt of el‘ing can occur, the interracial tension of the globules has been practically noutralised by diffusion of the pleas colloids to the sur- face an adsorption. If, however, the fat content of the product is high, the globules are relatively close together and clawing occurs bo- fero the adsorption has progressed far ouugh to reduce greatly the in- terglobnlo attraction. In this case further diffusion of the colloids to the interface and adsorption will be Itch greater on the outer sur-‘ face of the clun than on the inner surfaces. rhis will tend to leave fire or less nuisturbod the attraction botsecn the globules fol-sing the cluster or clusp and w explain the oesparative stability of tho ell-pa. (Dean (1'!) has denonstrated that pasteuriaation does not destroy the elusps to shy great extent.) It lust be sssuusi that even in the richest crease enough adsorption taboo place instantly, fro: the indi- ately surrounding plaon to provost a coalescence of the globules. "It sight be inferred that in the case of hcngcnised silk (low fat eesteet), where he sluupisg is produced, the individual shell globules prosentwould elulp on aging Just as the individual large globules es in urnl silk. his is not the case, however, all the only apparent on- planatienccesstebe thenchaeatcrnrowaiansovesent inthe case of the caller globules which are than everccses the inter-globule attrac- ticn." ' In explaining the plaon solids-fat ratio effect Dean (01) continues: “Increases in the must of plas. colloids would scan are available sur- face active nterial in tn i-cdiate vicinity of the scaly forscd sur- those after hcsogenisation which would, of course, tend to overcoat are quickly tn free surface enrgy created and prevent the attraction be- tween globules fren being so great. In such cases grouping would be greatly reduced in aunt, if not entirely prevented, depending on the colloid ooncentrat ions "rho increase of heugcniaor pressure was found to favor cluspix and since such increases in pressure create naller globules, sore fat surfaceandagreatertotal increase inthoanunt of interfaeialten- sion, tn i-odiately available plasn colloids, would be nrc quickly. exhausted without reducing the intor-globulo attraction to so low a do- grec as would occur with lesser pressures." no Pew (is) explained the increase in viscosity of hemgoniscd ice areas since as due to the greater dispersion of the fat and the increase in rat surface exposed. lartenseu (so) stated that the increased vio- oooity is due to the increased surface with the resulting fixation of a part of the ecrus and also to the inolocure of scruswithin the clusters. latenn all! Sharp (6) found hosogcnisation increased tn viscosity of silk when the cluape‘woro practically absent. neocllanoous Considerations more are a nuber of nisccllanooue eon- cidoraticns that my possibly be of value in a study of cross rising. his (80), after reviewing the literature, stated tnt the physical stateoftho fatwnnereasingtahoeplaeo influences the rate, thsti: silk is hold cold until tn fat becosos solid before crossing is per- sitted, the rate is decreased and best results are obtained with a ndiun or low teqerature with tn fat in a seal-solid condition. according to ten has and Sirks (so) the surface tension betscen theuilhiatsudtheuilhylesuehedneertact onooparations nhlbergandlcning (9) have ehownthat silkasd creasdecreasos insurfaco tenoionwithaninereaee infat andusuallydccreasoo in surface tension with aches It has been reported by Inhlberg m Wt (10) that tn spo- oific gravity of silk is not associated with creasing. la-r (83) believed that tn greater difference in specific grann- ity of the rat and earns at higher tauparstures than at ice-ester teuper- atures is responsible, in part at least, for tn closer packing of the . fat clusters and, therefore, a onllower areas lines the first theory stteepting to explainwhy sreasingwas increased by rapid cooling was advanced by Arnold (ll who stated that water is a better eondcotor of heat than fat, end tnroforo, when the teupersture of fitssilkvariceoitherupordownthewater inthosilkchangesin specific gravity are rapidly than tn fat and this tends to increase the difference in specific gravity between the too when the teqorature is falling. loln (30) has rated that soot investigators have found that ex- hscstireness or creasing is associated with cross values, and stated that them tn apparent cross vein. is not necessarily an index of thou-nut of fat thathasriscninthe cross, ingcneralthcsoet cos- plete area-ing is associated with the deepest orean layerse 3? PURPOSE OF THE EXPERIENT the purpose of this experisent was to determine the effect of the following factors on the separation of skis silk from bottled cross: 1. Effect of temperature of separation of milk (1) Fresh milk (2) 01d milk stored at low temperature 2. street of heat treatment of silk prior to separation 3. Effect of paeteurisaticn of cross (1) Rnw standardized cross (2) Green secured frcs pasteurisod milk 4.. Effect of high temperature of pasteurisation on the silk as compared with the cross used in standardisation 5. Effect of standardizing pasteurized cross with silk processed cs follows: (1) Raw whole milk (2) Pasteuriscd whole silk (3i Skis silk secured fros postscriaed silk 6. Effect of the following factors involved in standardisation: (l) Separating high test cream and stendardising back as compared with separating low test cross (2) Standardizing cross with whole milk as compared with atandardiaing with skin silk (3) Stundsrdising before as compared with after pasteurisa- tion (4) Temperature of standardization i5) Standardizing cross while fresh as compared with stand- ardising nfter storing 24 hours at low tomorature 7. 8e 9e 10. lls 12. 13. 14. Effect Effect Effect Effect Effect (1) (2) (Si (4) Effect (1) (2) (3) (4) (5) Effect Effect 58 of agitation of cream eftcr storm of rapid as compared with slow cooling of cross of temperature of crossing of time of crossing of viscolisation of raw cross temperature of visoolisation Pressure of viscoliaction Viscoliaing high test cross and standardizing with unviscolisod whole milk ' tiscolising only a portion of the cream of addition of salts Sodium carbonate Calcium chloride Di-calo ium phosphate Sodium citrate Ilene-calcium phosphate of addition of gelatin to the milk before separation of addition of evaporated milk, skis silk powder, and casein PLAN OF EEERIMEM'AL WORK Source of Milk Supply In order to eliminate large variations in the composition and previous treatment of the milk from day to day, and, in order that the results of this work should apply to commercial conditions insofar as possible, it was thought desirable that mixed milk should be used. lhe milk for these experiments was, therefore, obtained each day from the same 300 gallon Pfaudler pastem‘iaer in the college creamery after it had. been filled with milk delivered by the same group of milk patronse- nus mixed milk varied in temperature from 55° to 65" r. when received and the fat content varied from 3.4 to 3.8 per ccnte Processing the greater part of the processing was carried on in the experi- Intal laboratorye However, when milk and cream was needed in amunta too large to handle conveniently in the laboratory, this part of the processing was done in the creamsrye Ration For the major part of the experimental work, where only “All lots of cream were required, the milk was separated in the experi- mental laboratory using a De Laval, no. 12, electrically driven separ- ratore Preliminary runs were made to determine the proper cream screw setting to mks in order to obtain approximately the percentage of cream desired at the various tesperatures. The separator supply tank was filled with milk which had been heated to the proper temperature in the pasteuriaer. Approxiaately ens gallon of milk was allowed to run through the nohine in order to temer the separator before saving the samples of creamand skimmilke The creamsamplewasebtained fromthe remin- ing 25 pounds of milk in the supply tank. when large quantities of cream were needed it was separated in the college creamry with a lo. 40, electrically driven, De Laval separator. Pasteuriaation a Cherry-Barren 50 gallon, soil type, vat pasteuriser was used in pasteurising milk and cream in the laboratery. he coil sas kept running during both the heating and the holding period. ‘i'lm milk pasteurized in the creamsry was processed in a glass lined, 300 gallon, water-Jacket“ Pfaudler pasteuriaer with a propeller agitator which was. shut off during the holding period. Pasteurisaticn of cream in the creamery was accomplished with a 60 gallon water-jacketed Cherry-Darrell pasteuriaer with a propeller agitator. l'he pasteuriaation of cream for viscolisation was done in a water-Jacketed 100 gallon hedd Blue Line paeteuriser that was connected up directly to the visceliser with a pipe line. very small mute of milk and cream were pasteurized in one gallon cans by setting them in a tank of hot water and gently stirrixx the contents at frequent intervals. M135 'l'he cooling was done by three different methods. Some of the cooling was done in the pasteuriaing vats; son of it was ”compliehed by placing the cream or milk in one gallon cans in water and gently stirring at intervals, and the reminder of the cooling was done over a surface cooler. In each method cold water was the cooling medium and the product was cooled to approxismtely 50" r. for stadardisatien er tor the taking of samples. 41 Standardisation Large quantities of cream were standardized by weigh- ing on the springless scales in the creamery. Small quantities were standardised using dairy scales reading in tenths of pounds. With the exception of stored milk and cream which were standardized at the stor- age temperature, all the standardisation was done at near 50° r. unless otherwise stated. The cream was always standardised with skim milk from the some milk from which the cream was semared unless it is otherwise specifically stated in the results. £tation All stirring and agitating was done in one gallon ice cream cans with a stirring rod. uscolisation The cream, after being heated to the proper teqerature in the pasteuriser, was run through the viscoliscr at the various press- ures desired. Care was taken to assure accurate pressures and about two gallons of cream was allowed to run through the viscoliser after the desired pressure was obtained, to assure that the entire sample was processed at that pressure. A new Uhion Steam Pump Oompaw viscoliser of 200 gallons per hour capacity, containing a "Due-Visco" valve, was used. The samples were taken in one gallon cans directlyfrom the via-- ooliser, cooled, and set for creaminge Addition of Gelatin The gelatin was added to the milk before separa- tion instead of adding it to the cream. A high grade of comercial gelatin was used. It was carefully weighed on scales sensitive to 0.1 of a gram, mixed with one pint of cold water and heated in a tank of hot water until completely dissolved. The dissolved gelatin was then added to a 60 pound lot of milk, in the pasteuriser, at 120° F. as the milk was being heated to 145° 1‘. for separation. addition 93 Salt! The sodium carbonate, calcium chloride, mac-cal- cium phosphate and sodium citrate solutions were made up in distilled water so that five cc. of the solution would give 0.1 per cent of the salt when added to a 500 cc. sample of cream. rive cc., 15 cc., and 85 cc. of each of these solutions were added to the cream, by means of a pipette, at 100° to 110° r., the cream being stirred well during the addition of the solutions. A saturated solution of di-calcium phosphate, which was not so soluble in water, was added in be same quantities. Addition in; Condensed _l_t_i_l_k_,__ll_i_l_k_ 33513 3:139:22 These products were weighed on the same scales used in weighing the salts and gelatin. and were added at approximately 110° 1., the cream being stirred gently until the condensed milk, milk powder, and casein were thoroualy dis- solved. The condensed milk used was a well known cousrcial brand of sterilised un-sweetensd evaporated silk which had been condensed 100 per seat. liilk powder, testing 95 per cent solids, made by the spray pro- cess, was obtained from a. local unufacturer. The casein used was a cosmercial brand of soluble food casein. fithods g_f_ 3&5 m £21; 9529.13. Samples were taken in order to determine the amount of the skim milk layer appearing in the cream and, also, to ebserve the distinctness er attention-attracting power of this 1mr as evidenced first by the sharpness of the line of de- nrcatiom between the lsyers, and, second by the difference in the ap- pearance of the cream and skim milk layers as a result of the complete- ness of separation of the fat. It was believed at first that both ob- servations could be made by setting the cream in standard 100 cc. grad- uated cylinders which were need to determine the enonnt of the layer of I. I. skim milk. Preliminary runs, however, showed the distinctness of the layer was always much greater in bottles than in the cylinders. M1" were, therefore, taken in both cylinders and one-half pint cream bottles - in cylinders to determine the amount of the skim milk layer and in the 1 bottles to observe the distinctness of this layer. The samples were taken after the cream had been cooled to about 60" r. The cylinders and bottles were then cooled in ice water to e0° F. and set away for ores-ing. gem rature of. Storage and w The milk and cream was stored in the cold storage room of the creamery which ranged in temperature from so to 40° r. 111 samples set for croaming were placed in this room with the exception of a few samples in that part of the experiment treating with the effect of temperature of creaming. In this study samples were set in ice water in the cold room at 32° 1., in an electric refrigerator held constant between as and 41° 1., in cold running eater neinteined at 56" r. end in a culture control oven hept at es to 70" r. he drops of 40 per cent formaldehyde were added to each pint of cream as a pre- servative after preliminary study showed the addition of this reagent in considerably larger quantities had no noticeable effect on cream ris- 1118. Description of Tests made and Observed Butterfat Es}; me milk and cream were tested for butterfat by the habcock method. Immature The temperature of heating and cooling the milk and cream in the various treatments was observed with dairy thermometers graduated to read to two degrees Fahrenheit. Each thermmeter was checked for ac- .44 curacy against one knovn to be accurate. Regular observations of the thermmters ads accurate temperature control possible. Observation EM 352: he observations of creasing were made after 48 hours except when it was necessary to study the results after 12 hours cresminge Considerable difficulty eas encountered in this part of the work especially in observing the creasing in the cylinders there the separation of the layers was far less distinct than in the bottles. the fat soluble 4,... Men III, was used in an attempt to here more ao- curute and more reliable readings possible but without success. A mic- roscopic light was tried in order to standardise the source of light for the observations. Preliminary work, however, shoved tlmt the best. source of light sas indirect sunlight which was used in nking all ob- servations. Ehe folloving alphabetical and numricsl system was adOpted as a mans of recording the distinctness, and as a means of arriving at the average distinctness of the skim milk layers. ) +1 i Skim milk layer very distinct) 2 l - s ) + e B Skim milk layer quite distinct) 5 l - 6 ) + 7 c Skim milk layer fairly distinct) 8 ) - 9 D Skim milk layer not very distinct’ u ) ~13 ) +15 E Skim milk layer barely noticeable) 14 ) --15 F No distinct skim milk layer but ) + 16 showing a difference in appear- ) l7 ance between the bottom and upper) - 18 contents due to some separation ) of skim milk I ') +19 6 lo evident separation of skim milk) on 3 ~21 Plus and mimic signs were used to show time gradations in distimt- ness. I‘hile layers of the same distinctness were probably not always placed in the some class due to differences in tin intensity of the light from day to day due to cloudiness, and the impossibility of having a pernnent standard of comparison, the data, however, should be reliable in giving comparative results. he observations were checked by some member of the staff who was not informed as to the previous treatment of the samples. when the cream line was so indistinct that accurate reading was impossible, this is shown in the tables by an asterisk (II). leatheri_n_§ 323 In testing the viscolised cream for feathering the eorree was ends with water from the college supply which contained 100 parts per million of calcium. The coffee was nintained at 190-»m0fi l. and the cream was added a drop at a time from a stirring rode RESULTS Effect of Temperature of Separation Fresh Milk The temperature of fresh milk at the time of separation was found to have an influence on both the amount and the distinctness of the skim milk layer as shown in Tables 1, 2, and 3. Separation of the milk at the receiving temperature, 55° to 55° r., gave a deeper skin I milk later than did separation at any of the higher temperatures. This ‘ difference was very evident in the bottled cream as well as in the cyl- inders. Temperatures of separation ranging from 90° to 180° F. were found to have little influence on the amount of the skim milk layer that appeared in bottled cream. Separation at the receiving temperature, 65° to 65° F... or at 90° 3., gave a considerably more distinct skim milk layer than did separation at 120° r. or above. it 145° 1. the layer was more distinct than at 120° F. This difference, however, was only slight and might have been due to the effect of heat on the milk during the time required for the separation process, since pasteurization at 145° F. for 50 minutes, as will be shown in the consideration of the effect of pasteurization, was found to increase the distinctness of the layer. The influence of the temperature of separation at 90° and 120° 1‘. varied depending upon whether the milk was being heated up to those temp- eratures or was being cooled from a higher temperature. Pasteurising milk at 1450 F. for 50 minutes followed by subsequent cooling to 12:00 and 90° F. for separation gave no appreciable difference in the distinct- uses or volume of the skim milk layer at the two temperatures. 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Hilk Stored at Low Tenperature Results reported in the literature suggested that it might be possible to alter the "creaming off" phenomna by storing milk at a low temperature for a sufficient time to harden the fat and then controlling the temperature of separation. 'The results of storing for 24 and 48 hours at 35° to 40° F. and separating after slowly and carefully warming the milk to the various temperatures are given in Table 4. The temperature of separation was found to have little effect on the amount of the skim milk layer as little difference was shown at any of the temperatures from 60° to 14.50 P. The results indicate that the time of storing the milk at low temperature had little influence up- on the volume of the skim milk layer as compared to that obtained from fresh milk, except at 60° F. is compared with fresh milk separated at 55° to 65° 3., separation of old stored milk at 60° F. reduced the skim milk layer from 2.83 per cent in case of the fresh milk to 2.07 per cent in case of the old milk. The volume of the skim milk layer was, there- fore, reduced approximately 27 per cent due to storing the milk at low temperature. for unaccountable reasons there was considerable variation in the distinctness of the skim milk layer when old milk was separated at 500 2. It was found that raising the temperature of the milk from 50° F. to 80° or 90° r. and separating, a mob more distinct skim milk layer was formed than when the old milk was separated at 60° 3. Results of separation of old milk at 30°, 90°, 120°, and 145° 1?. revealed that 51 em." omou +n +m +m 14 o o.m 4H.“ bo.m n.om noma o.ma m.om n.0m n.0m n.mu «.oa N.o~ mp¢m w.mn «a.» .oh4 o a o o a a.“ o.N o.a o.m 0." 0.0m m.oa n.ma o.o~ coma o.o~ o.mu m.mn 0.0a o.¢m H4 ea 4.» o n n 4 4 n . o o.n o.u a.» o.o~ o.oa 0.0a o.ou 0.0m 0.0m m.ma 0.0m o.on o.¢~ 04 4a 5.» p o u 4 .4 o a.» m.~ a.” p.” n.a o.cu n.ma o.o~ 0.0m n.o~ o.om n.0a o.om 0.0m n.mm A4 «a no.n o to h 4 4 . o com a.» n.o~ o.Hm o.ou o.ou o.om o.am ooom 0.9" on we mo.n m o m 4. o 0.“ noa N.H o.m o.Hm n.ma coam n.o« o.a~ m.mn coam 0.5m 04 04 son 4 o n 4 4 n o.“ o.H a.“ n.n 0.“ 0.0m n.ma o.mH 0.0a o.o~ o.om n.ma o.ma 0.0a noun an «4 4.n n 3m n m 4 o.m oom o.m o.a o.oa n.ma o.am o.nm 0.0m n.0H o.H~ 0.9m 04 w¢ won a nu. m h o 0.4 . 0.0a m.ma o.aH m.o~ n.n~ 0.5m an m4 won a m¢a ONH 0m cm on 04a omH om om ow m¢a oma om Co on nee can cm 00 on .m nmohMmc aoapuudmmm no nodoandmom. doauom unaoa m onfipuuomaoa no onsadnogaos noflpuudmom noapuudmom owunovm .m ooafixafia .pa human sans once uom .h 04 no ouspuuogaoa no ouspwnomaoa no qua non no no Hague Baum no son an onsonomv «goo pom .saouo pace aom pu.xafiznvouovm puma anonmbqammmn, nomnn{xH«5Ua«Mm .upm mo puma 9am adfimwkmo pummwwmm no .9508 mmma yum nodadnamom on uoaum Jana douopm no «unapdoua econ no panama .bH ounce 52 there was little difference in the effect of separating old milk as com- pared with fresh milk separated at similar temperatures on the distinct- ness of the skim milk layer, as the old milk also gave a much less dis- tinct layer at 120° than 80° or 900 1?. and raising the temperature from 1200 to 145° increased the distinctness to a slight extent. Effect of Pasteurization of Milk Prior to Separation In view of the results given in the literature in regard to the ef- fect of temperature on the creaming of milk, surprising results were ob- tained in the study of pasteurization upon the skim milk layer forming in cream. The results of separating milk after heating to 1450 F. momentarily; after paeteurizing at 145° F. for 30 minutes; after pasteuriaing at 145° 1'. and cooling to 120° 1m after pasteurizing at 160° 1?. for 15 minutes; and after raising the milk pasteurized at 160° F. to 180° F., indicate with the exception of the milk separated at 160° r. to: 15 mimites, that the pasteurization had little influence upon the amount of the skim milk layer. When milk pasteurized at 160° 1'. for 15 minutes was skimmed at that temperature it was found that a smaller volume of skim milk appeared than at any other temperature of pasteurization. These results are sheen in |tables l, 2, and 3. It was found that heating milk to 145° F. and separating imediately resulted in a slightly more distinct skim milk layer than that obtained in the check sample at 90° 3., and that pasteurising at 145° 1'. for 50 minutes ads for a marked increase in the distinctness of the layer. Pasteurization at 160° F. for 15 minutes, or at this same exposure fol- lowed by raising the temperature to 180° F. momentarily, before separat- ing, gave a slightly more distinct skim milk layer than when the milk 53 was heated only to 145° F. momentarily. These results are indicated in table 3. However, since temperatures of 160° and 1800 F. as well as pasteurizing at 145° F. for 50 minutes, gave only a slight increase in distinctness as compared to that shown by heating to 145o F., these re- sults indicate that the higher temperatures of heating milk, 160° and 180° 3., did not appreciably increase or decrease the distinctness of . o the layer as compared with the usual exposure of 145 F. for 30 minutes. Effect of Pasteurization of Cream Raw Stanisrdized Cream The results obtained by pasteurizing raw stand- ardized cream are given in Table 5. Pasteurizing cream at each of the five degree intervals from 145° to 160° F. for 50 minutes yielded a skim milk layer of less volume and greater distinctness than did raw cream. The different temperatures of pasteurization used between 145° and 160° F. apparently had no marked influence on either the volume or distinct- mess of the layer. Approximately 1.9 per cent skim milk layer appeared in the cream obtained from the pasteurized lots as compared to 2.5 per cent from the raw cream. o Cream from Pasteurized Milk Pasteurizing standardized cream at 145 F. and 160° F. for 30 minutes apparently had no appreciable effect either on the volume or on the distinctness of the skim milk layer as shown by the results in Table 6. 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These results indicate there was little difference in the amunt of the skim milk layer due to high temperature of pasteurization of the skim milk as compared to the same treatment on the cream before standardizing. The detrimental effect was much greater, however, when the cream was pasteurized after standardizing. When the cream and skim milk were so- cured from pasteurized milk rather than from raw milk similar results were obtained. These results are shown in Table 8. The distinctness, however, was much greater when the skim milk was pasteurized before stamiardizing, in the case of raw products, while there was little dif- ference in the distinctness with the different treatments when the cream and skim milk were secured from pasteurized milk. Effect of Standardizing Pasteurized Cream with Milk Processed in Various Ways High test cream was pasteurized at 145° F. for so mimites and then standardized with (l) raw whole milk, (2) pasteurized whole milk, and (3) skim milk from pasteurized milk. The results, as given in Table 9, indicate that there was no marked difference in the volume of the serum layer obtained from the cream standardized with the different products. In... 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E 0. 0.3.3.8330 0o .03....003 00E 0. 08000 .HHHb 0.369 0.0m 58 0 on +0 .6 I0 acom omen mm?" azom «18 5.8 «.md .34 I0 +0 9 now now o 0.8. 0.0“ 0.0m on m3 0:3. 03 I 0m 0 m m In o.m com o.m 0.0m m.om 028 on mg as: ooa I om d o o 9 com wJ o.m 0.8 ooam 0.3 on Q3 add. 03 I om n o o 0 m4 m!" 06.. 0.0m 0.0m 04m. on mi 0.3 00.” I om N I o a I p4 m4 I 0.8.. m.om on m3 90¢ ooa I cm A Hand “2.9 £32 $93 .993 . .pmdm Bonn 39S. 395 295 395 325 89G 39:» 308.» 5.ng .bmdm 3am Baum .pudm tam 336 $35 ham 5%: :33 6333933 598 8:: Jam .53 ..m.mod R ..m 33.26 6333235 8398 €80 nan .53 non 256.. .939 8.390 soapaamom “£3 ”as 3% .mooeamn 3 932 3 388 .3m 580 no no mo .02 no 3230533 .353 fig 835 no name pom noapduanfiouodm anon. 03:39an Hana cam mafia dmuagouoam Bonn Mada 3.3m :3 and J35.“ 305.... vouansopmdm .m. 32.3 395 ham «3 Anal 3.3.6 dosagopmdm wsaaavuddsdpm Mo vacuum .NH 0.3g 59 The distinctness of the layer, however, was less in every case when raw whole milk was used in standardizing as compared with pasteurized whole milk, or pasteurized skim milk. Effect of Standardization Effect 21; Separatirg High Test Cream and Standardizing Back Versus Sepa- m .1!!! _T_e_s_t_ .9392 Since many milk plant Operators are of the opinion that high test cream standardized back to a low fat content gives a greater skim milk layer than cream separated at a lower fat content which requires less standardizing, an attempt was made to prove or dis- prove this assumption. Table 10 was made by taking the averages from Tables 1 and 2 of both high test standardized cream and low test unstand- ardized cream separated at 90°, 120°, and 145°F. The results show a tendency toward higher volumes of skim milk layer in the high test cream standardized back to approximately 20 per cent as compared with the cream separated as near 20 per cent as possible and not standardized. However, with many difficult readings due to the indistinctness of the skim milk layers in the cylinders in this experiment, definite conclusions should not be drawn. There was apparently no significant differences in the distinctness of skim milk layer between the standardized and unstandard- ized cream. - Effect 9.1:. Standardizing with Whole versus Skim Milk It has been assumed by some milk dealers that the skim milk layer is greater in volume when high testing cream is standardized with skim milk than when whole milk is used as the standardizing medium. The results of standardizing raw cream w. to n cm o.m «com nmoa m.o~ n.mH m.o~ o.ofl coma m.om as.» m n In +m. o.m anew m.m o.om H.0fl moma m.a¢ n.m¢ n.0n w¢.n a med 0mm om med qua om men oma om med . Qua cm on aeoaMou .h newswou .m assumed on condom on condom o» deacon .m aeoHMec moflpdusmom o» moapdnsmom ca noflvcuemom noapeucaom no R acanm anmapcoaa anew uoaam encapsoas seem on noaum ensvsnoaaoa MHfis uoheq mags saga .mOomnmn as canon we anmepcona poem ammo neg . no naedna no uuou¢onaouan Ashen mafia admm adono .vpm adoao we pass .oz no vaomwasm woos new mom .HH and H meapme Bonn nexus commumbd aflopssfioaaaq 3 seem .538 €3.80 pea neg mqanaeaueqepm .3 3an .vsuuevpsm «nee no“ om .H.oapms 61 with both raw whole and raw skim milk as given in Table 11 and the re- sults of standardizing pasteurized cream with pasteurized whole and with pasteurized skim milk as given in Table 9 indicate that there was-little difference in either the amount of the skim milk layer or in its dis- tinctness due to this factor. When pasteurized products were used less volume of skim milk layer appeared in the cream than when raw products were standardized. This appears to substantiate the former results ob- tained showing that pasteurization decreased the skim milk layer. In studying the effect of standardization before as compared with after pasteurization, raw cream was standardized with raw whole milk and pas- teurized. The results were compared with those obtained by pasteuriz-e ing the high test cream before standardizing with pasteurized milk. The data given in Table 12, although showing variations in results, in- dicates that the skim milk layer was somewhat greater in volume when the standardization was done prior to pasteurization as compared to standardizing with pasteurized products. An average skim milk volume of 1.9 per cent was found when standardized before pasteurizing as com- pared to 1.5 per cent when standardization was done after pasteurizing. There seemed to be no marked difference in distinctness as a result of the two methods. Effect .93 Temperature of Standardization Since temperature had been found to exert an effect on the appearance of the skim milk layer. in the processes of separation and pasteurization it was thought possible that the temperature of the milk and cream at the time er mixing in standard- isation might have an influence. However, the results of four trials run on the same day, mixing hot and cold cream and milk in all possible oom- 62 a In new n.m meow neon o.m¢ .ehd n .+n new new 0.0m 0.0m o.mm OHM I mm o n n m.m n.m o.om neon m.a¢ can I mm m a n n.m n.m o.om n.0m o.m¢ OHH I mm m a m new o.~ m.nm o.om cows 00H I om n n n o.» m.m 0.0m o.o~ o.¢¢ 00H I om m n o o.m o.m o.HN o.H~ n.d¢ 00H I om a 5mm gone age macaw 5.3m Sons near a»? n33 .38 R deaddnddncpm 860.6 douadnsdnspm 8.3.5 uses non 2.3.8 ..m assumed .oz nutmeg mafia pass you scene .65 no woupdudmom Heaps 83m no amonpogpma ..m oowImn as 930: we no pros «o 3333809 3.93 #32 3am vmom nah vim mafififfiuxm ham RN“ and mafia Odom? 3mm .H. mvHB.Edoho 3mm wcunwduddndvm «a vacuum .HN.erma 9 FL 63 Im In men men meow 438 ~33. .25 + 0 +0 o.~ can 0.0m 0.8 on mg 0.4% 00.." I 0m m m +m men N.m menu neon on mg 9.3 co." I cm a. o o N...” 02w. 0.0m 0.0m on 9A 0.3 03 I om n m o o!" o.m 0.3 0.8. on mg 9.3. con I om N n m «.0 men 0.0m 0.3 on mi 0.3 Go." I cm a .pmem .pmsm .vmam .pusm .uusm .vmcm no»: eaomem .3an oaomom .393 oaommm 332.353 scone douacaqqncpm 8.3.5 noapcuuvusdscpm 5a .héoc w“ ..m 33on .353 6695 name hem ammo you use .959 scope no.“ panama no ..mogImn as mason was 3.098 50.8 no no no .02 3390533 3.93 mag 838 ..Bm no dogmaagovoem coca 3333509 Henna «use new «new can 225 3333.3 5? wfifleeeeefim Semen 3333.3 520 rem .3 can Bea.» 5m spas $33.23..“ to»: 3293....” 3.3.6 a .sofieuuasopusm .334 .5 38mm asouo 3333355 Ho poommm .HHN ounce O O H 1 .' . i. H O O C C H . . l1 . . v ' '1 O . O . F ‘1 v . ' I ‘ fl 0 . 64 binationa, indicate that the temperature of neither the cream nor the ' milk had any appreciable effect on the amount or distinctness of the skim milk layer when raw cream was standardized with raw skim milk. These results are given in Table 13. Effect _o_f_' Standardizing Cream Fresh versus Standardizing After Storig £4; M Results of recreaming and agitation of stored milk as noted in the literature suggested that there might be a difference in "Cream- ing off” when the cream was standardized fresh as compared with standard- izing milk and cream stored at 35° to 40° F. for 24 hours. Table 14 gives the experimental results of a study of this influence with pasteur- ized cream and milk, indicating that there was a slightly greater serum layer when the cream was standardized fresh, whereas standardization after storing gave a layer of considerably greater distinctness. 0b- servation of the bottled cream showed that this difference in distinct- ness was probably great enough to deserve the consideration of the milk dealer. Effect of Agitation of Cream After Storing Green was stored in the cold storage room at 35-400 F. for 24 hours and agitated violently to determine if such agitation, after the fat was in a hardened condition, had any influence on the skim milk layer. Table 15 gives the observations made on this cream as compared with the same cream set fresh without agitation. It was found that agitation of pas- teurized cream after storing 24 hours has no significant effect upon the volunn of the skim milk layer. The stored, agitated cream did, however, give a more distinct layer. 65 .m can as as. "as 38 .m com ad was scone Boo ..m and: we as. is. pom .m and.” as was 53.3 you .3 o o o o 06. com com Com mmeom 3.0m. Heom 0.8 .34 o o u o o.m cem o.m cem 0.0m o.o~ 0.0m 0.0m m.mn «en 0: I mm a. o o o o o.m com oem Oem n.8,. m.om 98 0.0m 0&0 in o: I no n o o o o o.m Com com 02% 0.0m 0.0m Coon 0.0m 0&6 wen o: I mm m o o o o oem oem oem cem 0.8 n.0m 0.0m ooam memo “in o: I mm H O. §§ O! !. 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The rapid cooling was done over a surface cooler and the slow cooling ac- complished by occasional gentle agitation.of the cream set in cold water. The results, as presented in Table 16, indicated that the speed of cool- ing pasteurized creanihad little effect upon the volume or distinctness of the resulting skim.milk layer. Effect of Temperature of Creaming The results of various creaming temperatures upon.the appearance of the skim.milk layer are given in Table 17. These results indicate that there was no appreciable difference in.the amount or distinctness of the layer at ice water temperature, 32° F., as compared with 35 to 40° F. Later work, which was done after an.sccurate temperature controlled, electric refrigeratOr was obtained and the higher temperature constantly maintained at 59 to 41° 3., gave results indicating that ice water temper- ature yielded a slightly smaller serum layer and one which was also slight- ly more distinct than the layer which formed at 39 to 41° F. This small difference, however, was not enough to be of commercial importance. High- er temperatures gave less distinct layers as the temperature was raised. The amount of the layers could not be observed in the cylinders due to lack of distinctness of separation'but the bottles showed larger amounts at 56° F. and so to 70° F. with the latter temperature giving the great- er amount. 69 I0 0 34 men 3.0m 0.8. 0.3 .34 a +9 0...... 03m 0.0m I 0.8 on men 023 00H I 00 .v n 0 a.” o.m oJm I m.8 . on 9.." 0.3 00H I om n 0 0 09m o.m 0.3 I 0.3. on m: 0.3 00H I om m m m 03 «A 0.0m I 0.8.. or. m: 0.3 ooa I om H .oudpeuoaeoa mouuanoopmdm Boom woaaooo nonme_wosaeud0:eve.seon menace 0 +0 3.." 00.." m. 8.. «.3. .34 In I0 0.0 o.m 0.8. on mg: 0.43 00H I 00 n 0 m 03.. men Qua on 03 0:3 00." I 00 a. 9 I0 o.m o.m 0.8 on 0.3 one 00H I cm a m m n.” 0; 04m on m: 0.3 00." 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In In a q q o I I I mIN mIH NIH mION III on mIH m.o¢ 00H I om m m m m a m m I I I oIn oIN I 0.3” I I mom." om H «ma IIH mm mm mI IN mma IIH mm, mm II IN m .nfia .m.mmc a. .m‘mwoumou 930A 930: 83.8 x32 no 083 .939 8.3.5 “33.3.33 nmhdq Mada 83m “Emu pom Igm no "3393.5 3.3.5 no no .02 no 33.3059an .m 0313 pd puma ”H0363 ma no.3.“ vans onspduasg Hanna 3.3a Id: 23m “3m IISISIM ISQSIIm Gm .3336 mo 058 .3 Scam IHHE wands 72 Effect of Time of Creaming Several samples of cream were observed at various intervals to de- termine the effect of time of creaming on the appearance of the shim milk layer. Table 18, showing these results, indicates roughly that there was a gradual increase, the volume of the skim.milk layer becom- ing gradually less in.rate as the time increased. The amounts were dif- ficult to determine, however, especially after 96 hours as the skim.milk layers in the cylinders became less distinct. The distinctness seemed to increase for some 48 to 72 hours and then.gradually decreased. many observations in the study of the varioum factors were made at 96 hours in addition to the 48 hour observations, as a check on the first readings. It was always very evident that the distinctness was less at the 96 hour observation. In studying the effect of storing the milk and cream a day before standardizing, in.which a comparison of the stored, standardized sample was made with the check sample set raw on the fifth and sixth days of creaming respectively, it was found in.every case as shown in Table 14 that the samples were considerably less distinct after creaming five and six days than.after creaming only 48 hours. The skim milk lay- ers were slightly over twice as great in volume after the longer period of creaming. Effect of Viscolization of Raw Cream Effect of Temperature and.Pressure of Viscolization, Raw standardized cream was viscolized at both 145 and 150° F. It 500, 1000, 1500, 2000mm 2500 pounds pressure per square inch. The results given in Table 19 73 OOGMBIII nomad HHdEm II Io whoa 0.0m mw.n¢ Iobd m mIH OIQN nIHm 00H I mm ¢ 9 nIH 0.0m OIQn Goa I on 9 .?9 mod OIQN o.m¢ 00H I On N fa men OION 0.3 00H I on A 3028 .n :03 I. HINTSZZB I P $8».an AIR op Io HIN 0.0m mmIm¢ .ohd n QIN OION DIAQ cos I mm é In mIH OION 0.0» 00H I 0m n +9 MIN 0.0m.I 0.3 ooa I 0m N 9 N.m o.om o.m¢ 00H I om H «goons. Allowed as doauaoouaaIsb I mlmmospsoumrl. a u u OION mm.m¢ .obd a u . w IIIM IIQ anon anon anon anon one: one OION uIHm OHH I mm d o o c IIm . IIQ anon anon econ anon 9.0 Goa 0.0m 0.09 OHH I om n c a c a a anon anon anon anon one: ooa oION 0.0% can I On N a u u u 0 Quad one: one: anon 05.0 cod DION OImd can I om H . .m soma no wouflaoomdbin.mvwmmspsomfill o I I0 Io Io 0.0m mm.m¢ .ohd a 3.3m IIIQ IIm IIm 0:9» Quad 0:8 30“ odon 3H OION moan OHM I mm d o a IIIIo IIIo IIIo anon anon econ one: anon 06H 0.0m OImn cad I om n o c IIIR IIIQ IIQ one: anon one: anon an0 add OIQN o.m¢ Ofiu I om N a IIIm IIIQ IIQ IIQ anon anon anon nIO mboo mfia DION o.m¢ OHH I cm H Im odermd douaaoomab I d.bdoawdoum a m m o E as: a a .a same cannon endomoam.soapsuaaoomab $an “is scam no nmodpodfipman adono sum coaacasunspm no doapduaaooaab mo vacuum nussom oasmmoam_soavsaaaoonfib soapsaaa asoao_asouo soapsndmom pace non $83.96. .3 no no .02 .a @913 I. .33 3 so tasking 83m Iqaoa Inca puma oaspsaomeIa Heads and pea .KHH sands 74 show that low pressures greatly reduced the amount of "Greening off” as compared with the unviscolized cream and that the volume of the layer was reduced by increases in pressure until the layer was entirely elimi- nated. Since "Creaming off" was sometimes noted in the bottles where no separation of cream and serum was apparent in the cylinders this was tabulated in the results. A "Shall layer" indicate a that an appreciable amunt of separation took place and would probably be noticed by the cream buyer. A ”Trace" indicates a very mll layer, often noticed only after careful observation of the samples and would probably never be evi- dent to the consumer. It was found that at low pressures where the cream layer was not entirely eliminated, the small remaining layer was generally more distinct than the check, un-viscolized samples. Viscolization at 160° F. as compared with viscolization at 1450 F. generally gave a less distinct skim milk layer at low pressures, when a serum layer appeared. The layer was also usually entirely eliminated at a lower pressure when processed at 1600 F. as compared to 145° F., thus indicating that visco- lisation is more efficient at high than at low temperatures. Yiecolising raw cream at 1500 pounds pressure per square inch at 145° F. or 1000 pounds pressure at 1.60" F. ordinarily eliminated the skim milk layer en- tirely or reduced the layer to the extent that it would probably have passed unnoticed by the consumer. Effect 33 Viscolising High Test Cream Attempts to eliminate the skin nilk layer by viscolising high test cream before standardizing with un- viscolized milk proved unsuccessful as shown by the results given in Table 20. As compared with the un-viscoliaed cream in Table 19, the skim milk layer was always considerably reduced in volume due to this 75 treatment. The treatment, however, gave a much more distinct skim milk layer, thus overcoming the advantage of the reduced volume. In the first run of this series with 51.5 per cent cream, viscolising at 1500 pounds pressure per square inch, gave cream so viscous that it could hardly be poured and resembled partly whipped cream. It was found that even this high fat content cream, when standardized with unpviscolized milk, gave an appreciable skim milk layer. Since 1500 pounds pressure gave cream too heavy to handle well in the first lot, viscolisation of high test cream at this pressure was discontinued. It was always apparent that the higher the pressure and the higher the fat content, the greater was the viscosity of the cream. ME Viscolizing 29.113. Portion 33.312 25953 is has already been shown, viscolizing 20 percent cream at 2500 pounds pressure always en- tirely eliminated the skim milk layer. Comparing the results with those obtained with un-viscolized cream, it was found that mixing 10 per cent of viscolised cream with un-viscolized cream decreased the volume from 2.1 to 1.18 per cent or approximately 44 per cent. The treatment had no significant influence on the distinctness as compared with the check samples which had not been viscolized. The results of the mixed samples are given in Table 21 and may be compared with the un-viscolised samples in Table 19. Feathering Feathering tests run on three of the four series of viscolized cream gave no feathering whatsoever even when the cream had been processed at a pressure of 2500 pounds per square inch. 76 4 I4 ca 4 +m 3 14 god an; 3.8 3.8 8.3 .34 4 m I 0..” n4 men I o.mm 0.3. 0.3 co." I cm e .. +m a a a; a; a: .. . 93 0.3 0.3 02 .. 8 n I 4 4 I «.0 men as I 98 98 0.3 ooa I om m 4 4 4 o; 0..” as" men 0.8 0.8 98 0.3 on." I mm A com." 83 com com." 003 com 003 coo." com nausea season ..m .Mod 355a 5 3 souvesnooeg 5 5233383» no: uoapeazoosg m ..m assumed a oasmnoam no 0.33on I333 . Meagan aseao degeneaem he en “San 5am pace seal In; «a some new 50.8 no «c .02 no 383533 .m 08.3 as mason 3 cases: assuage tea 333.38. 35 Sass has 3am sages he twee 3a 3a 3:: sum deaaaooawblflp 5:3 Qamndfimdfigm .9390... Boone bum 3.3.300me No anchfim .NH 0.368 77 +n 3; 0.8 no.3 .34 o 0.." comm 3d 0.8 0.3 o: I mm s o 5.0 00.3 men 0.8 0.3 co." I 0a a a a; can... a: 98 o.3 8a .. cm a +n n!" comm 3.." 0.8 0.3 cc." I om a peas." congestion who nausea ..m assumed m m“ ..m eeeuwg #3: 33m dosages: no." coupes: scavsancoeab scene assoc ucaosnsaom no one: .MoodInn as cases 3 Icon: no no conga no Ho .03 Ivengua 3.3a Mag 3mm 3.33am eacpgeaaca «o puma «em some pea oncogene—ea H35 «season comm. encasenm AME vs Scene 33 no wean-Lem .0 genes»; mo pecan .8 ounce 78 Effect of Addition of Salts Detailed results of the addition of sodium carbonate, calcium chloride, di-calcium phosphate, sodium citrate, mono-calcium phosphate, and the check cream samples, both diluted with water equal to the vari- ous amounts of the salt solutions added, and undiluted cream, are shown in Tables 22 to 27 inclusive. The averages of these results are given in Table 28. The addition of 0.1 per cent sodium carbonate gave a con- siderably increased volume and a slightly sore distinct layer than the check samples. The addition of 0.3 and 0.5 per cent decreased the amount as compared with 0.1 per cent but a partial precipitation of the curd took place as demonstrated by the clear whey which was left in the bottom instead of the usual serum. The addition of calcium chloride in the vari- ous amounts apparently had no marked influence on the amount of the serum layer, but 0.3 and 0.5 per cent resulted in a less distinct layer. Di- calcium phosphate in the amounts added apparently had no measurable ef- fect on either the amount or distinctness of the skim milk layer. One- tenth per cent sodium citrate evidently had no marked effect on the vol- ume or distinctness of the layer, but 0.3 and 0.5 per cent increased both the volume and distinctness to a very marked extent. This may have been due to a partial precipitation of the casein for the serum was only slight- ly milky at the bottom indicating that the greater portion of the casein had been carried up with the fat. The addition of 5 cc., .15 cc. and 25 cc. of a saturated mono-calcium phosphate solution increased the volume of the serum with a very great increase in volume with the most concentrated sample. This salt also re- 79 .333 a. a3: .320 .. A a ..o 2.4 2.” 2...“ have .84 a n so o.m o.m a.” 98 on a: 0.3 02 .. 8 4 a a no as.“ 0.... 0.... 98 on a: o3... o3 .. cm a a a .6 n4 a; a.” 98 on a: 0.3 2: .. cm a a n no a: a; a.” 0.8. on me.” 93 8a .. cm a .3330 5320 .3330 5339 . E8 aoa 38 .Sa .3330 3538 .2 .28 Spas +4 +4 +0 3 nm 3.“ 8.... a.» 93 .24 ..+4 ..+4 ..m can a.» 03. 0.8 on 3.— 0.3. 2: .. om a ..+4 .14 ..m oé 3.. NJ ,o.8 on 3.. o.$ ooh .. 8 n 3+4 eevd +0 Gem oem men 0.8 on add 6.3 OOH I oo N .14 .14 3 o.” 0.“ mg" 0.8 on 3.. 93 02 .. o... a n. n. a. n. n. a. } 382.30 538. 38330 538 a .5: :38 m .a .858 33 23 race you 83.8 8.3. .988 nacho nouaeusaem .33 in. aqua £8 8a 832333 5.8 no «a no .8 no 38359.3 .a ocean a. 28a 3 ca 2.9 pea 3332833 28. pea .Qpfloasoa Hera. .543 ad: Ham 06539.30 8.938 360.8 demandofiom on. madam Ho Q3363 Ho voohhm ..HB .35 O c C . C 1 ‘ 1 H ' ' ‘ g I C O C I h F" . a I I q . C L 1 2 U C . V U C I l ' v I C Q . I L—‘l I 0 j v I C C . C v ‘ ' C I HH'r-xH 80 scans a. ba- 3531 has 3 +4 +4 no 3.» an.» no.” 83 .2: 3+4 .34 no 8» 83 8a 88 on 3” 8.3 8H .. 8 3 3+4 3+4 .6 8n 8» 8H 88 on 3” 83 o2 .. 8 n 3+4 3+4 .6 8m 8... 8H 88. on 3” 83 o8 .. 8 a .34 3+4 to . 8a a.» 8A 88. on 3a 83 02 .. 8 a 23.38 538 3830 588 £80 .38 38 .23 £933 538 .5 ER flea. ..o no .5 3 ..o 8; m8" 8: 83 .25 no no nu 8m 8... 8H 88 on 3d 83 08 .. 8 3 ..o ..o ..o 8... 8a 8a 88 or. 3H 83 o2 .. 8 n no no 3 8H 8a 8a 88 8 3H 83 o2 .. 8 a no .5 +9 8." 8” 8m 88. or. 3H 83 08 .. 8 A a. n. H. o. n. H. 33823 53313 328an 5339.8 m .3: v.33 m ..m 32mg 33 non £80 .39 6.3.5 08.5 .939 6.3.5 death-mom 3w...” “:9 5am 38 8m uoflugafi 3.3.6 «o no no .02 .3 32383.3 ..m 818 e. 933 3 .3 33 pan Expands?!” 38 pan 938858 .35 ouofirfig sum 328 SE 5370-3 awoke umuuhdovmdm 0» mpadm no nadaaddd Ho voohnfl .HHH .bHHN ensue b C C O In I I o I .‘ . I D a a o 1 F1 H 'r’-' l—a o I v o '-— ”fl V—fi 3'1 9 o v I! O l{}l 1 . I! ‘ o o uaOc u le—v I 0“!- '. ‘bfi—w ' I I I‘.Q O :'-1 .... . I .r 7 I o ' . HH'TH' I .I’V . . l 1. | ' XIII . 81 63.6.3300 65.6 9:. c.3238 32m:- 25 3 In In In Io no.» on; 3..." 2..." 0.3. .054 In In I I0 ”J o.u I o.” 0.3 on 3." 0.3 cc." I on ¢ Io I0 I I0 o.u od I men 0.8 on 3.." 02$ 00." I om . n Io Io Io Io a!" n!— oJ 83 0.0.9. on mi 0.3 cc." I on « Io Io Io Io men s..." s..." m4 0.8 on 0.3 0.3 can I on H mm 3 o 33 mm 3 a quad nag .3 con 393m .3 com 3 834 no»; .3 .oz 3 .884 .38 .8 .8 .3956 328 .P AER .38 n n +n 3 I0 3.0 am.“ an.« 0.3 .34 :5 n .39 lo n.h o.» O.» Ooou an add 0.3 can I om ¢ 2.3.9 .5 I0 0.9 o.n m.~ 0.8 on a: 0.3 ooa I cm a :3 n .59. +n now no." God 008 on 8d 0.3 OOH I on N 3. n :9 +n o.o 0.." o.~ 0.8.. on 3d 0.3 cc." I on A mm 3 n on m.— m . enhanced.“ Haggai 33395 537703: R .5: ..méoc R ..m :53 .3 yoga . 69.3986 598 alas .33. 50.6 «833.38 up?” £8 aim «:3 gum 832483.... 598 no no no .8 no 3233339 ..m ooeInr. an 933 3 no «39 Ram nogoflpdovnum :8. pg egg-mace dawns auburn» flaw HEMH noapdaom 3.6384 6325:»... I opdammonm gaoadoéan .> 53.8 donannovnam on 2:3 mo dogs“: no vacuum .HBR 0.33. ff O. I I l I ’(fit ' F1?! ..‘l.'. H Ha». F1 H 82 no no no no 84 8.” 8.” 84 0.8 on R: 8:3. 878 e .3956 .328 8 3 n Boa mu 8 n 88 II 6033 you»: .00 dog.» .883 .00 n n .53.:6 .. 86 8.». 8.... I 98 on a: 93 878 4. 329.8 5370.88 8 8 o 28a 8 B n 8.2 33.- 98332. .00 dogs #0338 .00 +4 +4 .0 .. 8.» 8.9 84 .. 0.8 8 8H 98 878 e 33?... 538m .6 ..o .n 3 ..o .. 8; 8; 84 .. 98 or. 3." 33 878 4. 3.38.8 5370.3 ..n n no a 84 2.4 2.; .. 88 on 3" 83 878 a .3830 3538 +4 .4 3 3 ..m u 84 88 o.» .. 0.8 on SA 93 878 4. 3.8.88 538 m. n. H. 282 o. n. H. 38m v.8. was. 88. «7. a .3: do a 883 pg no 33 non 8.09.5 059.9995 3.3.6 H393 .383 “a: 3% 33 Em .Bm no 3.38 .3 Ho. -88 .72.... 884 «in «a 3.3.523 .m .84..» a. 932 3 82.. 83.3 «.8 .3 .8 8.8..“ #3.: 5mm 5% Innovadm 3pm .955 .85 man .. Bun 33.9 8.58 539.5 daagoandm on 3:8 Ho “gonads we gonna .HHEHN canon. duced the distinctness of the layer to a slight extent, particularly when 15 cc. and 25 cc. additions of the solution were made. The 15 00. concentration caused a slight precipitation of the curd, and the 25 cc. concentration caused a considerable precipitation which was noticed. dur- ingthe agitation of the samples at the time the solution was added. Effect of Addition of Gelatin Very interesting results were obtained by adding smll amounts of gelatin as Table 29 indicates. It was found that by adding 0.1 per cent gelatin, the amount of the layer was probably increased slightly, al- though accurate readings were difficult due to the fact tint this amount of the colloid gave a layer of considerable less distinctness than the check samples containing no gelatin. Two-tenths per cent gelatin on the other hand gave a reduction of approximately 25 per cent in the skim milk layer volume as compared to the check sample but showed a layer of much greater distinctness. With the exception of one trial where a trace of layer was evident, it was found that 0.3 per cent gelatin eliminated and 0.4 per cent always entirely eliminated the layer. Effect of Addition of Evaporated Milk and Skim Milk Powder Since it is understood that condensed milk solids are being added at a few commercial plants in an attempt to control the skim milk layer in bottled cream trials were made to determine the effect of adding evaporated milk and skim milk powder. These were added in 0.5, 1.0, 2.0, and 5.0 per cent amounts with the results given in Table 50. One-half 84 .089 .. 4 .. 4 ..n ...e «4; mod an.“ nan 83 8.4“ 4:... 88 an.» .34 ... a 4 a .. .. 38a a; o.» .. u 8.8 98 Q8 .. 44H m.» o a a +4 9 o 282 33H «.4 o.» o.m 0.4“ 0.3. oém oAm o.8 044 a.» a n a 4 in .. .. 28a a; o.» .. .. .33 83 m4... .. 4.44 a.» 4 a a 4 E 0 38 23a to 0.» ad ca... 98. 0.3 98. 8.8 44H m.» n .. m.w 4 no .. 282 .82 a; o...“ .. .. 0.8 0.8. 0.3 .. n44. _ a.» ... a ..4 4 ..o m 83H 46 a... o.“ . 3.. 98. ad... c.4m 0.8. ed... 84 a.» H + “Means. 3028. 4. n. m. 4.0 Ban 4. n. .... 1o Boa 4. n. m. 4.0 38a fin. 3 4.8. gas 3 4.8. ads 3 88.. .mo 4 £3.33 ammo mom navdaomflvdmo mom nmmhmm pdoo gem dogma x23 8&3 Mada 8.3m anon Mom goo heal {snow Ho .02 a. 383523 .a 004.6» a. .23 m4 58.6 .3 .3 439 72a .83 ”:4: 3% pump can .33 wwm soapafiaom 3 82m “:42 .8 3 39474 no 33344 .3 83am .NB 0.3.08 85 n n ...o o no 8». 88 88 0.8 88 88. .34 n n I0 0 o 83! com a.» com com 88 on 3.— .o.mJ co." I om m M n to o n 832 o.m 0.8 o.m o.m 0.3 or. 9: 0.9. co." I om a 63.3 nousom voddd 3.30m x5: 336 £30 uom 3.33 83m 33 Mom 33.8 603.3039” 3. nodsom 33% 5.36 mo ”33.3.3 no woman .HNHM 0.369 a m a lo Io no." u.” o.m com 88 0.3 .22 a H a lo 0 932 8H m!” o.~ o.m 88 on mg 0.3. co.— .. om m u m a lo a 232 n4 men o.~ o.m 0.8 on 3." 0.3 co." I cm H com com 0.." n. 382 06 o.m 0.." m. 282 334 fig 334 fig 28 .52 .883 w .m 398% dopmuomdkm puma nmm copauomwbm “Emu Mom you 039 .938 8.3.5 noggqom 9093 #32 53m £80 90% 3.3.8 33.8 no no no .02 no 339039qu ..m in a... mason 3 Jam no «3363.33me anon. 9393.309 .339 O .33 “as 93m 33 £8 £8 860.8 603945».on on Mag coeduoqg ho nowflddd ho acouum dog 0.33.. 86 per cent of evaporated milk had no marked influence on either the volume or distinctness of the layer. The amount was apparently decreased some and the distinctness decreased to a considerable extent by one and two per cent additions, the effects being greater when two per cent was added. The addition of five per cent of evaporated milk eliminated the layer en- tirely. The results fail to indicate that the skim milk powder, in any of the percentages added had an influence on the amount of the layer al— though accurate observations were difficult when the larger amounts were added. No separation was evident in the cylinders when five per cent powder was added, but a layer was discernible in the bottled cream. It was apparent, from the results, that although from one to five per cent skim milk powder was an aid in lessening the distinctness of the skim mill: layer, powder did not eliminate it entirely as did evaporated milk added at the rate of five per cent. Effect of Addition of Casein The results of four trials in adding 0.5 per cent casein are given in Table 32, and indicate clearly that casein, added in this amunt, in- creased the volume of the skim mill: layer. The check samples gave an average layer of 1.75 whereas the sample to which casein had been added averaged 3.88 per cent. There was, therefore, an increase in the layer of approximately 120 per cent due to the addition of casein. There also seemed to be a tendency for the distinctness of the layer to be increased althmgh this effect was not pronounced. 87 +0 on o to ma.» oped 0.8 0.3 .ebd ....o no n3 m4 0.8 on 0.3 cc." I on a. .5 no 0.... m4 o.o~ on o.$ 8H .. 8 .... o ..o a.» a; o.o~ on 0.3 8a .. ow « o to o.» 0.." 0.8 on 0.3 co." I on .— 533 £028 533 £028 £30 new! .mfl— «bee and ..m eeoauWod ”Boo yea m5 pace non m.b 3.3.8 8.3. 33.8 noggmom news!“ “Sufi Beam name new 23% no 598 no He no .02 no 338333 ..m 031mm we .33 3 tea pea eageflfiofiem toe «ea 838.959 129 ....th AHE— 6.3m 50.8 on ”Sumac Ho donaaddd Ho vacuum oHHNHH 0."me 88 DISCUSSION In view of the results obtained in this study it is impossible to explain many ofthe findings upon our present limited theories in regard to cream rising. Some of the results tend to complicate, rather than to simplify, the search for the fundamental causes responsible for the phe- nomena of cream rising. The results obtained from separating fresh milk at various tempera- tures indicate that the condition of the fat at the time of separation had an influence upon the distinctness of the skim milk layer. The layer was most distinct when the separation was done under conditions when the fat globules were partially in the solid and partially in the liquid state. These results support the belief that the distinctness, in this case, is due to a more exhaustive rising of the fat globules made possible by the influence of the separator in aiding the clumping of the globules under these conditions. The obtaining of the least distinct layer at 120° F. is probably best explained as being due to the greater amount of breaking up of the fat globule clusters, and possibly also, to the breaking up of the globules themselves, to a slight extent, at this temperature. It was always noted that heating either the whole milk prior to sepa- ration, the cream following separation, or the skim milk before its use in standardizing raw cream always resulted in a more distinct skim milk layer. Pasteurizing the raw skim milk before standardizing raw cream always gave a more distinct serum layer than pasteurizing the cream before standard- 89 ising with raw skim milk. These results on the distinctness were ob- tained whether there was a measurable change in the volume of the serum layer or not, although in many cases the layer was decreased. The effect of heat treatment of the milk and the cream on the vol- ume of the skim milk layer is difficult to correlate with any.definite cause because of variations in results. In general, however, when there was a measurable effect on the skim milk layer volume, due to the heat treatment, there was a decrease in volume. A. more distinct skim milk layer, as well as a layer of less volume was, in general, the result of heating the milk and cream. This relationship between the volume of- layer and its distinctness is to be expected as greater grouping of the fat clusters in cream rising make both for an increased cream layer, or less serum layer, and also for a more exhaustive creaming, which promtes a more distinct cream line. It is well to keep in mind, nevertheless, that the volume of the cream that is formed is probably dependent upon the exhaustiveness of creaming and Upon. the size and rigidity of the clusters. that are formed. The latter is, without doubt, far more important in affecting the volum of the skim milk layer in cream. The former, while probably of consider- able importance in milk, is of minor importance in affecting the volume of the skim milk layer in cream, due to the relatively shall volume of this layer. The explanation of a decreased serum layer, as well as a more dis- tinct one, in cream, as a result of pasteurization is a difficult one to make. The results indicate greater clustering of the fat globules, as a result of pasteurization which is Just Opposite the effects that have 90 been obtained in milk. The increased concentration of fat globules in cream as compared to milk, which would make for greater chance cf con- tact and, therefore, greater coalescence of the globules in cream as com- pared to milk, may be a factor in explaining the results obtained. The elimination through separation of the small residual fat globules, which are continually in motion due to Brownian movement, may also be a factor as their movement would probably aid in preventing the permanent coales- cence of the fat globules and might even disintegrate forming clusters. Differences in interfacial tension and adsorption my also be in- volved. It is possible that there may be a change in the ratio of al- bumin and globulin to calcium caseinate broxght about by separation and concentration of the fat. It has been demonstrated, as was shown in the review of literature, that the whey colloids, lactalbumin and lacto-glo- bulin aided cream rising, whereas calcium caseinate was a deterrent to cream rising, and the effect of each was increased by pasteurization. It has been stated in the literature that the fat actually seems to protect milk against the detrimental effects of pasteurization. The in- creased fat content in cream may, therefore, be a factor in making for a more distinct skim milk layer, as well' as a layer of less volume when raw cream is pasteurized. Whatever the heat action may be in cream that ef- fects the creaming phenomena, it is apparently as complete, due to heat- ing at 145° F. for 30 minutes as at 150°, 155°, or 160° F. for the same period. The more distinct skim milk layer due to pasteurization may possi- bly be due, in part at least, to a precipitation of some of the serm 91 colloids, probably calcium caseinate, and the removal of a large part of this precipitate from the skim milk layer through . filtering action exerted by the large clusters of fat globules formed in the cream. The increased distinctness as a result of pasteurizing the skim milk used to standardize raw cream supports the belief that the effect of heat upon the distinctness is an effect upon the serum and, therefore, lends evidence in favor of this explanation. The precipitation of the same colloidal constituent or constituents, into larger aggregates on aging at low temperature, possibly as a result of change in hydrogen ion concentration, would also help. to explain the results secured in which it was noted that the distinctness decreased after 48 to 72 hours creaming. Here the fat has already risen and the precipitated colloids would be left in the serum. The change in size of the particles would account for a change in the appearance of the serum layer. The opposite effect of high temperature pasteurization, 170° F. for 20 minutes, on the cream, which gave increased skim milk layer volumes may have been due to the "oiling off” of some of the fat which was ob- served to occur. This pasteurization was done by setting the cans in hot water and stirring frequently. lie-pasteurization of cream from pasteurized milk apparently did not enhance the effect of heating the milk to am appreciable extent. This indicates that the effect of heat is complete, or nearly so, as a result of the first exposure. 92 The more distinct skim milk layer formed as a result of'agitating after storing and standardizing after 24 hours storage may have been.due, in part at least, to the fact that the fat globule clusters, which had formed, were not easily broken.up by agitation at a cold temperature. These large clusters may have exerted a filtering action on.the single globules and very small clusters. This would result in.a more complete separation of the fat from the serum and would, therefore, give a more distinct skim.milk layer. The increased distinctness as a result of viscolizing only a portion of the creanican also be explained on this basis as viscolizing at 145° F. is known to create large clumps of fat. The smaller serum.volume in case of the standardized cream, which was handled with a minimum of agitation, was probably due to little break- ing up of clusters that had formed. Since these clusters were of'hard- ened fat they were quite rigid and would not pack closely, thereby inp creasing the cream volume and reducing the skim milk layer. When.the cream was thoroughly agitated the clusters were broken.up to a greater extent and, therefore, the smaller clusters packed more closely giving a greater skim milk layer. The increase in volume of the skim milk layer on standing after some 48 to 72 hours was, without doubt, due to the gradual closer packing of the fat globule clusters. The increased volume and decreased distinctness of the skim milk layer resulting from increases in.temperature of creaming were probably due both to a less exhaustive creaming, and to a closer packing of the gldbules since the higher temperatures give a less rigid structure to the fat clusters. 93 The explanation of the greater efficiency of viscolization at 160° F. as compared to 145° F. was probably due to greater diapersion and less clumping of the fat globules at the higher temperature. Since the higher the pressure and the higher the fat content, the greater the viscosity of the cream obtained by viscolization, it indi- cated that greater fat clumping takes place with increases in pressure and percentage of fat, assuming that the increase in viscosity may be attributed both to the clumping of the fat globules and to a fixation of a portion of the serum through adsorption and also to the trapping of some serum within the clusters. . The mechanism of the action of gelatin is not thoroughly understood. It is believed that the addition of 0.2 per cent gelatin accelerated the slumping as a result of adsorption while the separation of free serum is entirely eliminated by the addition of from 0.3 to 0.4 per cent due to the gelatine colloid greatly increasing the viscosity, thus preventing the rising of the fat globules. The results of adding 0.1 per cent gela-" tin indicated that limited adsorption of the colloid may be a deterrent to fat clumping and cream rising. The cause of the effect of adding evaporated whole milk and powdered skim milk in decreasing the separation of the serum layer is not complete- ly understood. The increase in viscosity, however, is believed to be a contributing factor. Though the skim milk layer was not always most distinct under con- ditions causing a decreased layer, in general, there was an inverse re- lationship between the volume and distinctness of the layer. .‘ 94 Until very small layers amounting only to a trace were formed, as was obtained in the results of viscolization, it is believed from ob- servations on this work, that the distinctness is as important a factor as the volume in drawing the attention of the consumer to the existence of the layer. The writer is aware of the impossibility of explaining satisfactori- ly in all cases the results obtained in this study. Milk is one of the most complex natural appearing colloids and, for that reason, since little is yet definitely known concerning the complex phenomenon of cream rising, it is realized that many unknown, but yet fundamental factors may be ex- erting an influence that cannot be eliminated from the experiment. The complexity of it all makes definite explanations difficult. The above discussion is, therefore, offered as a possible partial explanation of some of the results obtained after careful consideration of the many factors involved. 95 CONCLUSIOHS l. The separation.of fresh milk, after receiving at 55° to 65° F., at temperatures ranging from90o to 1800 F. had little influence on the volume of the skim milk layer. Separating at the receiving temperature resulted in an increased skim milk layer as compared to the higher temp- eratures of separation. Freshly received milk gave a more distinct skim milk layer when separated at the receiving temperature, 550 to 650 F., or when raised to 900 F. than.when separated after raising to 120 or 145° F. Fresh milk heated to 120° F. and separated at that temperature gave a less distinct layer than when separated at any other temperature. When the milk was cooled from.pasteurization temperature, however, and separated at 1200 and 900 F. there was no measurable difference in distinctness. 2. Storing mdlk at a low temperature prior to separation at 80°, 90°. 120°, and 145° F., had little influence upon the volume of the skim milk layer appearing in cream as compared with that secured from fresh milk. When separated at 60° F. the stored milk gave a reduced layer as compared to that obtained from fresh milk. Separation of fresh milk at 55° to 55° F. gave a more distinct layer than.did old milk separated at 60° F. Stor- ing had no appreciable influence on the distinctness of the serum.layer at the 90°, 120°, and 145° F. temperatures of separation. o 3. Heating milk prior to separation at temperatures of 145 F. for 30 mdnntes and 1800 F. momentarily had no marked effect upon the volume of the skim milk layer. Pasteurizing milk at 160°F. for 15 minutes de- creased the volume of the layer. 96 Heating the milk to 145° F. momentarily before separation in- creased the distinctness of the skim milk layer as compared with lower temperatures. Holding the milk for 30 minutes at 1450 F. or pasteuriz- ing at higher temperatures increased the distinctness of the layer. file higher temperatures of pasteurization, 160° and 180° r., did not appre- ciably change the distinctness as compared with the usual exposure of 145° 2. 4. Pasteurizing raw cream at 145°, 150°, 155°, and 160° F. for 50 minutes decreased the volume and increased the distinctness of the skim milk layer. The different temperatures of pasteurization had no apparent effect on either the volume or the distinctness of the layer. 5. Pasteurizing cream standardized to 30 per cent, secured from milk pasteurized at 145° and 160° 1?. for 50 minutes had no appreciable effect either on the volume or on the distinctness of the skim milk layer. 5. High temperature pasteurization, 170° 1?. for 20 minutes, of high test cream before standardization as compared to the same treatment on the skim milk before standardization, gave little difference in the vol- ume of the skim milk layer, whereas, high temperature pasteurization of the standardized cream gave a greatly increased layer. lPhis was true with both raw products and products secured from pasteurized milk. Pasteurizing the raw skim milk at high temperatures before stand- ardizing gave a more distinct serum layer than when pasteurizing the raw high test cream before standardizing or when pasteurizing the standard- ized 20 per cent cream. There was no marked difference in the distinct- ness of the serum layer due to the exposure of the high test cream and skim milk secured from pasteurized milk to high temperatures prior to standard izat ion. 4‘ 97 7. Stamiardization of pasteurized cream with raw whole milk, with pasteurized whole milk and with skim milk secured from pasteurized. milk gave no appreciable differences in the volume of the skim milk layer. Standardization with raw whole milk gave a less distinct layer than standardization either with pasteurized whole milk or with skim milk secured from pasteurized milk. There was no apparent difference in distinctness when pasteurized whole milk and when skim milk from pas- teurized milk were used in standardization. 8. No definite conclusions can be drawn in regard to the effect of standardizing back high test cream as compared to separatinghlow test cream on the volume of the skim milk layer, although there seemed to be a tendency for the cream standardized back to give a slightly greater layer. There was no apparent difference in the distinctness of the layer between the standardized and unstandardized cream. 9. There was little difference in either the amunt or the distinct- ness of the skim milk layer as a result of standardizing raw cream with raw whole milk as compared to standardizing with raw skim milk. 10. Standardization after pasteurizing the cream and the milk at 145° F. for 30 minutes gave a skim milk layer of slightly less volume than when the cream was standardized previous to pasteurization. There seemed be little difference in the distinctness .3 a result of the two methods. 11. The temperature of the milk and cream at the time of standardiza- tion had no measurable influence upon either the volume or the distinct- ness of the skim milk layer. 98 12. Standardization.of milk and cream.stored at a low temperature for 24 hours gave a skim.milk layer of slightly less volume and a layer of considerably increased distinctness when.compared with the layer in cream standardized with fresh milk and cream. 13. Agitating pasteurized cream.which had been.stored at 35 to 40° F. for 24 hours had no significant influence upon.the volume of the serum layer. The layer was more distinct than that in the cream set fresh. 14. The speed of cooling pasteurized cream.apparently had little effect upon the volume, or the distinctness of the skim milk layer. 15. An increase in.the temperature of creaming above 320 F. increased the volume and decreased the distinctness of the skim milk layer.{ 16. The volume of the skim milk layer increased gradually and with decreasing rate as the cream was held. The distinctness seemed to inp crease for some 48 to 72 hours and then.gradually decreased. 17. Viscolizing cream at 2500 pounds pressure always elimdnated the serum layer. Low pressures reduced the volume of the layer but increased its distinctness. Viscolizing at 1600 F. at all pressures was found to be more ef- ficient than viscolizing at 145° B. When the serum layer appeared it was always less distinct at low pressures. Furthermore, the layer was elimi- nated entirely at a lower pressure when processed at 1600 F. than.when processed at 145° F. 18. Viscolizing high test cream.and standardizing with unviscolized milk greatly reduced the volume of the skim.milk layer, but greatly in- creased the distinctness of the layer. 99 19. Mixing 10 per cent of cream viscolized at 1450 F. with.unvisco- lized cream.reduced the layer almost 50 per cent as compared with the layer forming on unviscolized cream. The distinctness was not influenced to any marked extent. 20. The salts added gave various results. Di-calcium phOSphate ap- parently had no influence either upon the volume or upon the distinctness of the layer. Calcium chloride, while having no apparent effect upon the volume, decreased the distinctness to some extent. The other salts added, sodiunlcitrate, sodium.carbonate, and mono-calcium.phosphate apparently did not influence "creaming off" until amounts were added that partially or totally precipitated the casein. 21. The addition of 0.1 of one per cent gelatin decreased the dis- tinctness and apparently increased the amount of the layer. Two-tenths of one per cent gelatin reduced the amount of the layer considerably, but gave a very distinct skim milk layer. From 0.3 to 0.4 of one per cent entirely eliminated the separation.of the serum.from the cream. 22. Skim milk powder, in the amounts added failed to have a measur- able effect upon the volume of the skim milk layer. The distinctness became less with increases in the amount of the skim.milk‘pwoder added. The addition of five per cent of the powder, although it did not elimi- nate the layer, reduced its distinctness to a great extent. 25. The addition of five per cent evaporated whole milk entirely eliminated the serum layer. Smaller amounts, down.to one per cent, re- duced both the volume and the distinctness of the layer. The influence was greaer on the distinctness than on the volume. 100 24. The addition of 0.5 of one per cent casein increased the vol- ume of the layer and apparently increased the distinctness slightly, although not to a pronounced extent. l. 2. 3. 4. 5. 6. 7. 101 BIBLIOGRAPHY Arnold, L. B. 1876 American Dairying Rural Home Pub. Co., Rochester, N. Y. Babcock, S. M. 1891 Creaming Experiments Wis. Agr. Expt. Sta. Bul. No. 29. Babcock, S. M. 1889 The Constitution of Milk and Some of the Conditions which Affect the Separation of Cream Wis. Agr. Exp. Sta. B111. 18. Babcock, S. M. and Russell, H. L. 1896 Conditions Affecting the Consistency of Milk Wis. Agr. Exp. Sta. 15th Annual Rpt., 73-80. Bancroft, W. D. 1921 Applied Colloid Chemistry, lst Ed. McCraw-Hill Book Co., N. Y. Bateman, Geo. M. and. Sharp, Paul F. 1928 A. 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B. 1924 The Effect of Milk Plant Operations on the Amount of Cream Rising on Milk Jour. Dairy Sci. VII, 197-204. 38. 39. 41. 42. 106 Mattick, E. C. V. and Hallett, H. S. 1929 The Effect of Heat on Milk Jour. Agr. Sci., XIX, 452-462. McInerney, T. J. 1917 Clarification of Milk New York (Cornell) Agr. Exp. Sta. Bul. 389. Mortensen, M. 1918 Factors Which Influence the Yield and Consistency of Ice Cream Iowa Agr. Exp. Sta. Bul. 180. Mortensen, M. 1927 Effect of Homogenization on Milk, Cream, and Ice Cream Iowa Agr. Exp. Sta. Rpt., p. 32. Palmer, L. S. 1921 The Effect of Heat on the Calcium Salts and Rennet Coagula- bility of Cows Milk . Proc. Soc. Exp. Biol. and Med. XIX, 157-142. Palmer, L. S. 1923 The Chemistry of Dairy Products from a Colloidal Standpoint Proc. Worlds Dairy Cong. Vol. 2, 1157-1166 Govt. Printing Office, Washington, D. c.) Palmer, 1.. S. and Anderson, E. 0. 1922 Factors Influencing the Viscosity of Milk and Their Relation to Creaming Minn. Agr. Exp. Sta. Annual Rpt., p. '59. 45. 47. 49. 50. 107 Palmer, L. S. and Anderson, E. 0. 1926 Physico-Chemical Factors Influencing Cream Rising - I, Viscosity Jour. Dairy Sci. IX, 1-15. Palmer, 1.. 8., Hening. J. C. and Anderson, E. 0. 1926 Physico-Chemical Factors Influencing Cream Rising - II, Relation of Plasma Colloids to Pasteurization Effects Jour. Dairy Sci., IX, 171-191. Plumb, C. S. O 1895 Dairy Experiment Ind. Agr. Exp. Sta. Bul. 44. Prieger, Inge 1950 The Films of Milk Fat Globules Bio-Chem. z. 217, 551-6 Abst. in Chem. Abst. XXIV, p. 1906. Rahn, 0. 1921 Cream Formation Forsch. Geb. Milchw. Molkereuves I; 155-54 3. 215-55 Abst. in Chem. Abst. XVI, 2941, '22. Rahn, 0. 1922 Observations on the Greening of Milk Kolloid 3. XXX, 110—114 Abst. in Exp. Sta. Rec. XLVII, 514. 51. 52. 55. 54. 55. 56. 57. 108 Rahn, 0. 1925 The Division of Fat in Milk Milchw. Forsch. II, 585—404 Abst. in Chem. Abst. XXI, 2942, '27. Reid, Wm. H. 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O I Q C o I 58. 59. 60. 61. 62. 65. 64. 65. 109 Sherwood, F. H. and Smallfield, H. L. 1926 Factors Influencing the Viscosity of Cream and Ice Cream Jour. Dairy Sci. IX., 68-77. Sirks, H. A. 1924 The Agglutination of Fat Corpuscles and their Electric Charge Verslag. land. orderzoek. Ridkslandboumproefsta XXIX, 157-152 Abst. in Chem. Abst. XIX, 501, '25. Sommer, H. H. and E. B. Hart 1919 The Heat Coagulation of Milk Jour. Biol. Chem. XL, 157-151. Sommer, H. H. and North, G. C. 1950 Electric Charge in Milk Found to Have Important Influence Wisconsin Agr. Exp. Sta. Bul. 410, p. 25. Titus, R. 7.7., Sommer, H. H. and Hart, E. B. 1928 The Nature of the Proteins Surrounding the Fat Clobules in Milk Jour. Biol. Chem. LXXVI, 257-250. Tracy, P. H. and Ruehe, H. A. 1950 Factors Affecting the Heat Coagulation of Homogenized Coffee Cream Ill. Agr. Exp. Sta. Bul. 552. Trout, G. Malcolm 1950 Cream Line Studies in Market Milk West Virginia Agr. Exp. Sta. Bul. 299. Troy, H. C. and Sharp, Paul Francis 1928 Physical Factors Influencing the Formation and Fat Control of Gravity Cream Jour. Dairy Sci. XI, 189-226. 66. 67. ° 68. 69. 70. 71. 72. 110 Van Dam, W. and Sirks, H. A. 1922 The Separation of Milk According to the Friesish System Verslag.‘Land. 0nderzoek Rijkslandbouwproefsta XXVI, 106-186 Abst. in Chem. Abst. XVII, 1285, '25. Van Slyke, L. L. and Bosworth, A. W. 1915 Condition of Casein and Salts in Milk Jour. Biol. Chem. XX, 135-152. Webb, Byron H. and Holm, Geo. E. 1928 The Heat Stability and Feathering of Sweet Cream as Affected by Different Homogenization Pressures and Different Tempera- tures of Forewarming Jour. Dairy Sci. , XI, 245-257. Whitaker, H. 1., Archibald, a. 9., Shore, L. and Clement, C. E. 1925 Effect of Various Factors on the Creaming Ability of Market Milk 2 U. S. D. A. Dapt. Bul. 1544. Whitaker, Randall, Sherman, J. M. and Sharp, Paul Francis 1927 Effect of Temperature on the Viscosity of Skim Milk Jour. Dairy Sci. X, 561-571. Wing, H. H. 1891 Cream Rising by Dilution New York (Cornell) Agr. Exp. Sta. Bul. 29. Wing, H. H. and Smith, Clinton D. 1890 Cream Rising by Dilution new YOrk (Cornell) Aer. Exp. Sta. Bul. 20. 73. 74. 75. 111 W011, F. U. 1895 The Effect of Pasteurization and Sterilization on the Vis- cosity and Fat Globules of Milk and Cream Wisconsin.Annua1 Rpt., 164-173. W011, F. W., Babcock, S. It and Russell, H. L. 1903 Conditions Affecting the Consistency of Milk ‘Wisconsin.£gr. Exp. Sta. 20th Annual Rpt. 183-187. Zoller, H. F. 1924 Casein.and the Dairy Industry The Theory and Application.of Colloidal Behavior, R. H. Bogus, vol. 11., 1st Ed., p. 798 McCrawéHill Book Co., New York. 112 Showing the Separation of the Skim Milk Layer from Cream ' I. .‘ V .~ 9 'M. A . 1 ‘.?l \- x "/‘WM‘J'IN ‘I . r ' J ,', ‘1‘ “I ' ll'.‘ " I p: n “ n V '2 a”) s; ' .‘ "x f": ' ‘ V'. 6‘". l ' >.-' .‘Im‘gzv I. ‘ ’ If: )" Jsrlt ." ’ .,,‘~ ‘."v\'.'. 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