éé IIIIIIIIIIIIIIIIIIIHIIIIIIIIIIIII SIGNIFICANCE OF THE COLON-AEROGENES GROUP IN ICE CREAM Thesis for the Degree of M. S- EARL \X’. COULTER I929 THESIS » . v M . III. lo I 7. (WV r ‘u .vli ,v ’ Illlfi. 1‘ 9 4"“ .f i v. Significau ("0 ' v +* . HA“! , ,. fl. ,, .,,, C or Lille 'JU.LOs¢-C~U1.0ilrglx . g. m-. ‘-'r‘ :..--' 1 ."}:1"\'. Hi) viOLLiJ ll; ICC leu.uo '.. U 'Ii-esis Submitted to the Facultv of tge Liehigau ptate College in partial fulfillment of the require eats for the degree of Lester of Science. THESIS Introduction. Historical. Procedure and gesults. 0 Determination of strains oi group shoving resistance to temperature commonly used. eerogenes group. Other factors affecting the viability of neubers of this group. Discussion. Simmer-y . Conclusions. Acknowledgment. References. 94935 *ne colon-serotenes the pasteurizing tip 3'. 1‘, - ..,.,-c°..,./.4.i o u", - —,,”,-. ‘7: . nifect o- tne inirecienus i me 106 0168...: xii}. upon tne viability of member s of the colon— p.‘ Significance of t e colon-aero:*e1es Group in Ice Crc am. lntr auction. A reyieu of tne 'ndustrial detelOpnent of this countrys10\s plainly that the surviving and tros perous industries are those thich have tended to build larger and larger units._ Enis consolidation generally results in a better product for the consumer. This has been particu- larly noticeable with respect to the ice or an industry. Gradually but steadily the small plants have been assimi- lated by tr e larcer organizati n . The result has been a noteworthy increase in the sanitary cuality of tile products offered for sale. Along tith.tnis industrial growth there has been a steady growth of those agencies designed to protect the public from insanitary products. The net facts constantly being discovered are broadening the field of the public health worker. The uork of the past few years has indicated a considerable amount of interest in the sanitation of’ frozen milk products. as the new facts have been made available, the vigilance of the public health authorities has increased correspondingly. Lew legislation is con- stantly being enacted better to control the sanitary quality of dairy products. At the present tine the facts available to the Public health officer are meager and of those standards which exist, hany have not been found acceptable. The confusion and nisunderstandin; which has resulted is only a natural phase in the develoenent of suitable Criteria. The folloming tor; pas undertaken thh the express desire of obtaining further information upon the signifi— cance of the colon-aerogenes group in ice cream. In con- nection tith this problem several questions present them- selves. hoes the presence of this group in retail ice cream indicate inefficient pasteurization or contamination after pasteurization? hhat is the possibility of nenbers of this group survivirg the pasteurization temperatures now in use? Is the health officer justified in condemning ice cream thich contains members of the colon—aerogenes group? It is hoped that the material submitted may be of some value in answering the above questions. 1' (4’. I'storical. Since the di iscover b7 Escherich in 1886 of I,J Esc lierichia coli, this rganism and related species have been a constant center of discussion and investig'tion. established the fact that {)1 As soon as ‘oiLers La Escherichia coli vas a constant inhcoi fant of the intestinal tract, its presence in rater supplies vas regarded as an index of fecal pollution. 1.un rous z.etiods for examination mere advanced uith the result that confirmatory vorh has a scarce a: la no standard form of :rocedure \as adOpte {3 After exteiu ive \.orh onotream pol ution in 1901, Jordan (1) concltded that thenever ex {tensive mortality occured among he colon bacteria a similar mortality could be assuned to have occured among the typhoid bacteria. Savage (2) in 1902 stated that alth ugh a knowledge of the number of Escherichia coli present is essential, arbitrary standards of allovable numbers are of little value. In 1908 Horton (a) sbidied ground raters and concluded that the presence of isc eiichia coli in drilled vell s is generally sufficient evidence to condemn that source. Stoughton (4) in lSOS questioned the \alue of the presump- tive test and presented data to shoy the unreliability of this Lethod of procedure. In the same year the Connittee on Taternna ysis of the Anerican lublic Health Association -‘ indings and tire revise d "5 published their report. These standards folloving have provided a standard procedure for the bacteriological examination of vater sup lies. Letailed qualitative and quantitative procedure for the deternination ..'.‘ rh w 1., ' 1' . .1.4 -.-‘ ' '. -. ~‘ - of “SCLdPlCulfi coli and related EbcClCS is an inpOitant J. feature of this report. The un of the \crl done ‘n (0 1'". q o_\'.. ‘H. o ‘. _‘V_. 1“, -. _1_(~__l _ f‘. 1. v.7“: ‘ nanericnia ceid.ini\:ater supplies IkJudu to she“: -iistq J. \ J. 1 I I. _ " ~ o ‘ A o "_ .0 f”. ’A‘- 1- t O n ”I _ 1 1 o tnat tnis OftflnlSh haltiplies last little, ll at all, in w 4-. .. ~ -. .. +1, . J— r , . 4 ' ' . natural \ater supplies, Lent, tnut a nuantitative ~ ‘. A . " ‘0 " ‘ n 4" . v " ‘. ..I fl ’0 .‘ .‘h".‘( 0‘) deteruuxuition c- LUJMLUFS oi m-lb gi'xag is of image lnleUbahLb 1 1, , -,_,. - J. 4. - , 4... -_ - .;,~ an. ,. . .n 4.x than tne dualitative test; and shat the scarce oi the AI‘ ‘ ‘0 *fl ‘, . V - ‘I,’ ‘: r‘ ‘p 0 "3 : , ~ .4. “. ‘ . 7 j . " ' D; ’3‘- .embers oi tulS r~_roup is or L,reat inpOItance in Q€bdrmlhint ». ¢-,~ ~1;4. , n — . ,4.,.,'- an- . the po Vaniii u" or. a :-1...;..p...cteu \attr supplg. . A .L' W as soon as .Le colon test for \ater supplies had become firnl' V ‘. ‘- establis ed, investigators turned their at- tention to milk. Che of the earlier papers in this field was published in 1908 by Bergey and beehan (a). The authors isolated fifty strains of the colon-aerogenes group from milk. The early zorl of this nature vas concerned primarily with the isolation and identification of seabers of this group. Iot until the pasteurization of bill becaue a COnnon practise did bacteriologists attenpt to find a reliable uethod for determining the efficiency of the pasteurization process. Lunerous studies were nade upon the flora of pasteurized nilk. In lilo Shippen (6) isolated thirty-one n strains or the colon-aerogenes group from pasteurized milk. He found that eleven of these strains possessed a therual death point above 00° C. for fifteen minutes. Three of the strains survived 6&0 C. for thirty minutes and three others 63° C. for thirty uinutes. The author concluded, "that the thermal death point of a given Species varies tith the dif- ferent strains of that Species. Certain strains of v. '4' .. t. ... ,. ~. ... w . ." 1- " ‘ ~31 H ‘V' ‘ ' ‘--'=‘ Ir ‘13-.fi \ . ‘1'! Escherichia coli are not nilldQ at the tenoeiatiies co Loni; fi 1‘ 1 . ‘-- he presence of neoneriCnia coli in F1 used in pasteurization. ‘ A 'v-y".‘ ‘ 0'11 A q, .‘_. ~. _ :A-“_ . . .' 1"” pasteurized niin cannot be taien as an ihuen of ltnyJLP pasteurization or sub-segment COiit'c‘LI'iill'atiOIio" In the sane L year ayers and Johnson (7) confirmed by an extensive study the variation of the thermal death point of henbers of this group. Txo hundred and seventy-four cultures Lere isolated, the najority beinr obtained from cow feces. Their method was to inoculate tubes of sterile litmus milk 11th four drOps of a broth culture of the strain to be studied. The tubes vere then heated in a constant temperature tater oath at various temperatures 30- thirty uinutes. The tubes mere cooled imnediately aid incubated at e70 C. Ihe reSults obtained indicated that many strains have a thermal death point close to 6L.;0 0. (1450 '11 .). Chey concluded that this as a test for ef- p. fact complicates the colon test, if use w'v fioiency of pasteurization, and further, that scherichia coli has a low Lajorit; thermal death point and the survival of some strains is due to a few resistant cells. The finding of large numbers of Escherichia coli immediately after pasteurization nitht be inte'preted as being ‘ue to inef- ficient heating or a heavy recontanination. Another paper by the same authors (8) published in 1924 shoved that a pasteurization temperature must be base’ upon the absolute thernal death point'as deterrined in the laooratorv. They concluded that large scale efficiency tests more not only unnecessary, but were apt to be hisleading. Jenkins (9) in 1‘? I“? 6 studied the fl ra of pasteurized silk and determined the 0.. ‘ a '~. I ..‘ a. .. ~ - ‘.. i~‘ .- r‘ . 0‘ I - 4 .' ‘L x. ' . . f : p .1": u r J ‘ 5’ J "‘ J ’y r,, 4'. ‘ ’ colon orianisn content », inane oi bile salt iWCVOso 5o tone (7* mater. The autLor stat=d tLat an effec tivelv tas eurizea will should not contain lactose fernentinq bacilli in one cubic - 4-. " J- ’ “ ‘ ‘ ‘ ”o. . P . . (I r w :“ fi ._1“ 1') . - Jar centin etcr 9nd bLLL’-L» one “seneiic'iia coli lo a. ‘.(J..L1LQU..LD iiiucn of the efficienc; of the Pasteurizin_ process. Sixteen nilk yla“ s more studied by StenarQOn (l0) 1 in l927, in an effoit to correi te bl; t yerfornance tith '\ \ r—L p... 4; 5. the ’ so erichia coli co 1 tent. Le Ased tern jsc-tmr chia coli to indicate all as b-rs of tne irony of C" n n-spore form- ‘ I V ing aerobic oacilli aluxni.fernent lactose Liiji‘finc production I? . ‘-_ P‘~ H .‘. ' " v" r 3%.. V —‘ _ ‘v _' . ‘ ‘ O f“. . _'_ - oi gas. .nie toiirxies saiiniiizeu.cm: follo.&.. rue cold.cxn:tent eurized nilk 1as found to vary COnsid ei abl; . Centrol 6 o i w ‘»r~ ““-— . ...-‘ V‘ ~.~ .' '3— .-~-. ‘.:. '~.- 7" 4»- cnarts -ron niin giants ticse Llln Lus niin in coii content snowed inproyer Leatinf or irregularit; of ;rocedure. The I \ a. - f‘ 1 charts indicated a dei ini te corre ia tion between coli content and plant procedure. A test for Lscbe r ni. coli can be used ‘. 1 | ' ' ‘ - 4‘ no‘p ’ ‘ ‘ - ' ‘ 'r ‘ I fi‘ r f.“ I" D -.‘ ‘- “ ‘ ’ _ ‘ to 0.16 CAL hi) Oil $14.22;... L .1C'L 4. 1’;‘15L‘LGI$CC O n Eltb~$AU—'-‘-.:. (.A. \. Lib .L‘ .1.O:b;50£4’\z o $.1 . ‘ -. o - l“ L Q _ . . ‘ c .‘v -“.-‘, o . n . J— o _ _ ’V 0 fl N” ior one LanlLuL generi';in Cell 0i Latu-uilbcu nlin. 1‘, -‘ A 1 ‘ . ~ ("‘1 —. . ‘4' .- r~ a\ ‘ . “ “rt uuzc (ll) in 19“! pOlneeu Out the Llf foi- -\ .‘ - . J-‘.. ”I .~ '. , -\.. 4' ' V I" -‘ r‘, .. ': ~ “ ' .“ r'“. "a elice thKIt/Ll- LnLQ—I‘ COLLlL bk‘Lu--U ill \~(--t"\lf L~¢Lu L11 lAAllJL. ‘L-b 4- ,4 4n -r~; 4‘ - .+: r :L- . : . .~Jm- n a -fi “v‘ w- =~ ELL). UALOI‘ QthCu iLsM ~‘ \-L{; lel-‘J-LJCEMAACEJ 0‘ Use-J CC4—Uli O-LI- ErujiLSl‘A ‘. -. - . _ 3". ‘ .' 1. ::u ' ',_ ,_ ._‘ . ' ... fi,‘ . Y¥¢Lell fOLLLlLL LAX X..Ll.rL .L A.) 1—11 ILU 7‘ '6‘.“ gut) & l V LA; U Ltd I J‘D;J~ .L ‘4"J-$-L£A- “ater. Tn’s fact is attributed to the Conditions t;culi9r to tile initfg;riinj Ci 1 ilji IZLlC:i 6:14:0t lye 13.111W313 eljiiinefinad. Tne scientific literature efnt; Ls nunerous buyers c-nccrnin no bacteriolcgg of i*e arena, but very few of these contei: 2:.-:ci=;.,l refer-once to the colon—acrogezws op O _ {. _ I w. ' -~.' _‘1 “_‘ —‘ n ‘ t “V‘ q \f K. . ( I 4‘ ' . L J _. ' 0' I J ._" 4 04- Oijgalllguli) o iJLLK/lictli (.L-n-o) ll- .1... 1U l..L~L.C ;.. CO..ilJlU ub‘ szLL: UL}. .LO" J--, -. -. 0 ‘ - fi - , I. f!r~ .f‘l :4 ‘l. - , 1,‘ V 1 ‘3‘) - ‘O" - . ‘3‘ .~ ’.’~ 3 - r~ l VL‘lLC... t. 1. '.\—~- u . A .5... .1 - ~._.L..L..L .1. (a v CA (J L‘AAL i; .L'u.l.‘. \. 5., lid. «-).; -LO.--U. 0 Out of siitg-sii ca three isolated use ideaiificd fort;- SeHm lOLLbu LO the crlan—eevogenes grtu3. isolation mes accoa3lieled 13 the use of bile salt lactose agar. Vle alin“ 3:1eeeit-d a bacteriological staiderd fc: ice cream "I ' ‘ J \llCh liiited Le cers c; 1:; CClCL- wezogcics gr u; LO L.l cc. of ice CICRQ a: Leesared b3 tne grodiction of acid and €33 in bilfi 3&3- {juicose ore 3. Ole oi‘tfix:;ioet co Ile te act yes recent l, 3ubliehed b3 ;ci4-ir and Harris (1;). liree uethods or deteruinimg the senitar3 quality f icc creau xere studied aid cog3ared. .Qese xere the total count, the coinn-aeroneles count add tLe anerebic spore test. -4e method used 4c: de 'iiiuiu the colon- &G"O:”i€h3 “Cunt k3¢5tJ3 folloiss: Ede £34i3le 143 be te3.t eii \as diluted 1 to l“, l to 100, aid 1 to 1,;c;,cco. Lactose bouill Oil earichgeat tubes were inoculated Lith 0.1 cc. por- tion of each dilution add all tubes slo;ia¢ more tlen 10 per ceat {as tore 31a ed ca Bado's agar. Tron these 31a typical colonies Mere fished and identified accordibb to the Standard Zetliods for later Alalysis a furnished by the ' " -' .~ r“: .4: ..-, ~ 10 unalta eeociatioi. -ae autlcgs CCuClhucQ I,.J American Eco k that the colozi- acrogenes count is of value in con rollir> the efficiency of p-steuriza tion and that it also indicates insa nit r3 conditions. The fact that it does not distinguish between initial contamination and subsegdent cultiplication was cited as a.distinct disadvantage. This brief SHLM‘“: indicates the need of further contributions to this field of research. file greatest need seeus to be for J I‘ significance cf hSMDCPS 0; cream. loaever, it difficu Inilli. products clusions ha? a to indicate tggse 'i .L viability of bonkers o be of sufficiuut vsluc to 7' ’~~ I; ‘ 44“ \‘fi (‘1 bbaliuk;4}¢ ..€ U.-La avid lties The numerous differences vtigation before J-‘I .- LuiiJ. 4‘ . x "‘ v".'a"- :.~. - *‘ ', OJ. Iii/(£1,134. Ctiiib Luib this grcui)\¢uni.30unu in.ice wilt i-L.Cxt this lji'oblcm 8.13;..liéd iea Pc-f f4 IJLE)“. a); .- +- «:31.» (’1 .re he ,— C\ (71' h' ' betyeen these two dairy definite con- -_ — ,. —‘ .. '1: 4 p 1“,... ,4- * - U‘x Little x01“ hub uucn cone ., . 4 Inks 14Cu investigation. affect the to to ~ -, . . ,7 ,1 Linase alone snou- lu. " ‘ J .- - o ‘ ‘ fir“ Iv .‘ . -+-. 1-.-. . V "’ _' """" ' at the outset 01. Le lQLlC/‘Lll-u study it tee needs“, a“ --‘ c ‘1 ‘ - to adOpt an accepteole nethod of pesteurizstion. Chin; to the (D ' “'1 I' 2‘. "‘ ‘0 ‘ ‘ -' n "‘ ' . 0" r1 ’1 ’ " I f ‘ ' ‘ "' " v larbe hunter or culture used it the hUCUSSafy to oncose sous i..J method vhich \ould reouire Smfil snoents of the Luterinl to «L be heated. Although the author realized that the t st tub C? A method of pasteurization is in ill repute, the d (n y A. (E 52;. f") p: I )C.‘ +\ u ‘ _~L"’_ Ulilb 1.1% ULLK) -‘J vantages possessed b“ Mere responsible for its adoption for this particular study. In an effort to Justify this nethod of procedure, extensive preliminary vork mas con- ducted in order to compare the rate of heat transfer 'n ihole milk and in ice cream mix. The results xere grutifying in- asmuch as they indicated very little difference in the rate ‘of heat transfer between these two media. It mes decided to confine the folloxing vorh as nuch as possible to a laboratory problem since facilities for p» P- I field vorl vere not available. The torh is conveniently vided into three parts as follows: the determination of strains of the colon-aerogenes group shovinb resistance to the pasteurizing temperatures commonly enplzyed, the effect of the various ingredients of the ice cream mix upon the viability of the members of the colon-serogehcs group, and other factors affecting the viebili y of nenbers of this group. Determination of resistant strain'. The cultures used throrghout this study vere inten- tionally secured from vurious sources. The majority of the F1 r strains were obtained frcn our luborstorg stocL cultures thich had be n isoluted from vuter supglies and from the digestive D tract oi «a .L. chiclens. A lie 0 the cultures is given in Table I toEether with their source then 3 ssible. As it was desirable to use a l'guid culture for inocu- lation purposes, the synthetic nediun developed by Lolloff (14) Les adopted. 3v the use of a synthetic medium variations in growth due to chsnres in constitition of a natural medium are largely eliminated. Lolloff's Ls dium contains the following: Lactose 5 gas. Anmoniun tsrtrate 5 ans. Ammonium thosuhete 0.62 Listilled tuter 1000 00. Five cubic centineter portions of tne ecove LEthm were dis- tributed into test tubes and sterilized in the sutoclev at fifteen pounds pressure for tnent; minutes. The deternination of living cells in cloudy medium presents numerous difficulties. As direct plating proved unss isfectory for this purpose, it was necessurg to resort to sore other nethod. The use of lactose broth fermentation tubes gave the desired results and so vere stpted for this 1 work. Stenderd extract broth v " adjusted so tndt the pH 93 ranged from 6.9 to 7.0. One per cent lactose and one per cent Andrsde's indicator more added. Five cubic centimeters of the mediun was distributed into Lurlsn fernentetion tubes minutes 0 and outocluved at fifteen pounds pressure for twent ‘t' \, U The production of ecid shu gus in this medium then inoculated vitn 0.1 cc. of tic inoculuu and incubated at 070 C. for 48 J. . f‘ ~-r f" 01 *r ‘ i ~~'-: v I) -. [-1- Ivr' r.‘-_ .3 hours mas ass umed to be ui stive oi bhc survival oi coli. Ciie first portion of the tor; mas concerned with the ice crean mix. This :aterial mas obtained directly from the holdin; taul of tLe College Luirv. The :ix is pasteurized at a tbidbiafui‘ of lééo F. (02.00 C.) for thirty minutes. The material mas first di st riouted in exactly l0 cc. amounts in Pyrex test tubes and then heated for fifteen minutes in flee— ing steam on tLo successive da;s. Tle uediuu thus prepared was tested for sterilit; by seeding a lactose broth fermenta- tion thbe Kith 001 CC. ELe cultures to be studied Lere vroVn in Lollo if's uedium for tLentg-four hours at 07° C. The sterile ice cream mix “as inoculate d vitn 0.1 cc. of this liguid culture. Chis amount contained fro; 10,00 to 50 ,000 bacteria as dete rmire d b: experiuental plating at the outset of the study. Care Vus Q. 3 ~talen thorougulg to agita e the seeded tubes to insure even (‘9‘ distribution of the inoculum. all tubes Vere then incubated for tuo hours at 57° C. At the end of this tiue lactose broth fermentation tubes inoculated with or 1e lOOp-full (inui. ) of the material alLa;s shoved acid and gas production after being in- cubated at 570 C. for t‘eflti-iOL“ heirs. All heating Operations vere carried out in a Le knot- inskv type electrically heated and cont; olled tater bat h. This apparatus permitted the accurate regulation of the bath temperature to within 0.10 C. After adju;tin¢ the bath to the - desired temperature, the tubes Vere inmersed to tithin one- *N. ‘- '. I D $ .’ .1 e 4* ~ D - ~ ‘10 '~ -" "~“'-."~T "' zlalf 1:1ch OJ. U Gilt tOL‘.S . £8. Uglve O- 106 cc: 68.1.1 In .).. CCL.U\L-ll¢.~l.él a thermometer was placed on the Opposite side of {he tunA from the bath thermometer. iAe 50 minute period of heating W s not recorded until the temperature of the material in the tubes had reached tAe telnpe ra t re of the tater bath. Inhediately after the coApletion of the heating period the tubes Lure cooled by imAers ion in col d mater. Lactos broth ferAeAtation tubes \.ere seeded tith 0.1 cc. of the heat- ed nix a Ad iAcubAE'i at 37° C. Aesults vere recorded after tnentg—four hours And forte-eight hour incubution periods. It mas soon found that the cultures shoved extrene variation in their viability as affected bv the heat i115 pro- cess. Repeated trials using the sAAe culture gave different results. Cuese variati As ar pos'ibly one to such factors (fl as, slight cfiuhqe in cenposition aAd p1 of the nix, variatiO‘ L. a; in the numbers of bacteria seeded, and the personal error of technic. HOLEVGP, bf a number of trials the relative viability of a particular cultire CUulu be established. In interp etiAL the following data it is assumed that any fer entation tube shoring at least 5 per ceAt gas production and sufficient acid to change the colcr of Andrade' s i 1dicator, is indicative of the survival of that strain at tAe tempei ature heated. The first teL1reu‘iture selec ted Les 140° F. (e00 C.). The difference in the effect on the viability of the coli on- aerogenes group then heat -d in ice cream nix aAd in skin milk was very barked. At this teAgerature it will be noticed from Table 2 that of the cultures heated in the ice cream mix 23 strains or oz per cent survived. The same cultures heated in luo skin milk shcx a survival of 18 strains or 40 per cent. The heating vas then repeated at a temnerature of lASO F. 62.30) ‘1" ’1 'u“ '5 1r " n+~ , “'- ‘ r" ' . s.“ ’7 “:1 -.‘-.1r:-'> ' T115 increased tt1.1erl‘e.eL11‘e 165311111.th 111 ‘c; 111E11'1111u (111101632119 1n the vi ability of the cultures as it is shown in rSable 3. In H 'I this case, 0. the cultures heated in ice creah nix only 10 strains or 22 per cent survived. The sane cultures heated in skim milk under identical conditions mere all deetr ye . By using a hi her teir; erature of lcOO F (60.50 C.) the re- ‘ sulfs given in Table 4 were oo;aineu. The cultures mere heated in ice creah iii and onlv four, or less than 1 ‘ cent, survived at this ten J. CO 1550 F. J. Che temperature mas again raised, this tine (68.80 C). ZEAJ<1ata tivez1iA1fhacle 5 sho:.1n3 Cultures lewxnic- J. . u o r . .‘ A" -- ‘ .. ~~ ' .r .- . f. —. " 1.- , in "'1 “‘u'.|' 4" "7 “ o 1': '3 '1 4"" f} 1111;, ctClL chit. gab 1-- 102C. 110.38 bl'Otmo A tb1113-bi 11-111138 111,: 119.31 1.111911 155° F. $8.20 C. ) .as ihuossible due to the fact that ice .~ .. ‘~ .- . 14-. .:- ° ._ '4, .f.-,.° , L a.“ cream LiA \As altered 1A its chasical state. 4. "1‘1- ' 1 " “‘ ‘1 1 J" 1‘ ' " '1 ‘. "l "' ' '.. . "‘ ‘. C" “‘9' ..1 . ,1 1Ae 8UOVC data sAo. tAat ic cieaw niA Aas a greater (E) protective effect han rho A by slir milk, or, perhaps, an added effect. The :uestien naturally ar'ses as to that factor or factors cause this protective action. In an attempt to learn more of this protective action, each of the eo1is itucnts of ti 1e ice cre an nix vere studied k=*iratelr to deternine ti1eir effect. ffect of the Ingredients of the Ice Cream Lin Upon the Via- bility of Tenbers of the Colon-aerogehes Group. After having demonst;Ated that the ice cream nix,as a vhole,eierts a certaiii protective influe11ce upon 1ent ers of FJ '4‘ C - ,. -. - 1 A .,- , .. , 7 .- 4-1.- :1 1. the colon-aero.enes ifOuj att enticn vas Lurhzu to .ne -uc- ‘l "5 V " ‘ ' .w‘.‘ ‘ J' y 1". C" '--\ 1 j, . J IQ(‘ -~ v ‘ " . . ”21)" .1 1'51 611-008 ‘1 !.lu.L CO ‘JO .~.-~--'3‘ LLEJ 1111'; 1.06 C;- vL-i.1 1-1;)». .541 {vVAJ-Cl“ ’ 4-‘-'—~ 1 . ~4- ~ ~v'...+-. ,n .. , r~ 4".- . unis ilodact consists t. a couree 0, lat sucn as cream, a \ f) " . ‘7 “ "‘ 1' 4' " J :--. '.‘- .“ fi‘i" “ '-~ '. 1- . W, " 1‘ fi‘ ‘ ’u SOL-.I‘Ce 01-- SOllUL'd ilk.) L. .1. C. u Lub-; 31...; .L '_ ’12.”. £11.]... 11.1.1.1- 01' 1.1.1.1.. .' 1- ,f .. ." - -,._ V, _ ..‘ , _ (‘1', W --1 1 - ,_ __ -I- .J. M111 potder, and 3&filung stcetenin. and steoiiizini agents a -v- of Lhich sucrOse a;d deletin are the most cennonle used. in VOPLihg :ith these varicuc inLredients an at emit 1as nade to studz tfigxr3111terials 111‘u1e sane conceniitjjxni in thich the; Ixnuxi l; occai*in1 the ice cnwnm1rni1. st'hnc formulae .1, 1..~-. °-» , .- .~. .-.——,-* - -.- «4- US‘u rt tne i-c cseau Manuiactlres are varied SUCOPQLnC b0 ‘ ‘ D -‘.‘ I‘. o f- “ . \ «‘< A .' + .. ‘ I’_ .‘ 1;. .' the demands o1 tic censumer, each in :tdie1. vas m1ae up in .-. 4.1- J- .. - ‘ ' ‘1. - -. 'V “4 ' . p“ , 3‘ J '1 ,. _ .. , “ _° .. J.” - . ., ' . - O i 3' ’ 1.3 ' 1" f‘ ’ .\ ’,l '7‘ 4‘ (J 1 .-f A : Y ‘ 1‘ ._‘ (10-1 Ciill-1-.,iu-.‘u \i1-L ’-1 1 UK.J.-\.4. 1.11le{2 11-.y.1.1‘d upon). ill 111.6 51.LLOLLU ‘P ) ~‘1 l!‘; '1'. (“"3 " lr‘I‘”q C'- 2.01.11“ va CV» ;~.L --1J\..L.v 0 mp. 1.‘ .1 z .x . J-‘ 1 f‘ -. J- ' .)4- 4. n J.‘ .. r ,..‘ . . «1 -L- . t -, ~ )1“ (- .. g. , LJv-L-.’ , {1.1 .I .-.U:; LI l... ivOL Uus. U 0... U..'w ‘ ’LLL‘ ul WvL'QsL UL) ’ g...-« 8 CO \. 1,7;51,.,._;..1 _’5i..-‘ :1 t C1}. :3 _v‘ 1'2, :- Z i n y‘ 5- ‘ 1’. 3.1:. r I“ 4“ ‘.‘ .[\ t“ r“. pf\llo- :' . r1». 1-1; kylv“ - lo 0 1-. Q;.Jv-1.k1._\ Jun.- I-C’Lb 1 swab 14.1.. (-1...» .LU nu. . ’- ' 1*: ‘\ ~ - ‘ J- 4. I- n— 4- ~ — ’ > ' ‘ r‘ ‘ ‘ ‘ T- ‘ r. K - ' '. - ' w P ‘ u- ' Ci- 8 --A A by U b-Li- ‘IU l'br OLA t '-‘s ngtl LK! ‘J (-5“ kkw JLL. Q‘ U LJ» {JV-UV . .L‘i 4. + ( w- fl. H ‘ " I. J- ; f. o . t O ‘- ‘-’- J— o I: w. ‘ r~ ‘ Ola r. L) (-4-. OJ. .1. L) u\~a£, ltn LIA..V 5.40;va .A0 .L a U AVA; L ‘44.- L , \ J LA JCL ‘. ‘ " L -" 'n “ ~ ‘. ' ‘- :u I- ' r n : ~ . A 5 .‘ .‘.‘ J‘ -‘ , n ‘ -“ L. ‘- ”‘1' ’1 81111011111112, 01. 2‘35“" wci’C tit-1.1.141... iv .61., 11:10. L.L.C.-11111._ C1; patCi‘. 1111:, .- .' ‘ '-....4- ._V, ,7.,4...- ,,.~ (a, , __ ~: 4. rez~zil‘:.‘11.i.r 1 1.uures c-1A14nreu o 5e11 Oi .in anL in :LiL .1lL a .) for flirt; Linutes. the Colon- t a "'4 h ', ~Jle-I~l-- 1 O _ ~. f“ " I (1‘ o q o '9’ Eatl‘E‘.lIl IC"; ‘JJ'UCfl; dl_l..- - 1.1.JL LO. AClQ Las Lcid Cas Lo. Ice n.-r— 'J 4.6: d'l.l . 4 ,. ‘7. .‘ . nClu was 3L1“ Kilk Acid jII-" LnxS F0 1' 1~ I I l~+++l l I l l +'+++++$~|~+~+1~+*++****+ I n I 114 116 120 131 .1— -r _,_ ‘f ,. 1'— 7,. 1L 7.. *— ~1- #L + 7L + ‘i‘i‘ii‘lw '*+'+""+'*+*~r+~++l+l + _,_ + _,_ .,. L. ,_ .,. .,_ + _,_ _,_ 4% + +++++' + ‘l' l 4. Won 7': .0 ~-.. ; . -, 4.: r1 ‘1 , E_iie -lL-ecrt 0-: .15-) ill. ci_ Lefl-tiinf - Le1n. of “we .Lcltqr- r. --.; .. , f- , --: 1'. 213m“ C-J._ .roLri i 10 'ce Cr . 1L. L-ri i1; LLLL. - lint e1; a . *1 ,:0 .n ... rw -_'_ _, 1'; ‘, T6. #:21‘5.tLLrC Of 11;: o (Uwou Co) 1.0.1 -.ll...'. t‘c .‘-..llU.t-CSO ‘I I _‘ ' )r' - s _ :7 : — r‘+- .- : J n I“ (-3-, - v. .. .. ‘I' Strain Ice C‘e:' uni“ .ilL ~train Ice L eau eLim “11L - v —. I . " l- "I ‘ I. ' . 0 Jr ‘ ‘1 . 4 O f 'Y ‘ ‘ 1.0 o [LULLL \JL.§5 :LUch up...) 1.0 o hUlu. ere...» nvlu. out.) o I D 7... 14 f— — _ e? __ __ + + C (.1 I I I l H C) (j: 51 - -— — - 1.20 .. _ _ _ w‘w. -Lu‘gg U The Sffect on Col\._tz;-£~ero.gc;ic:5 CthLwos '..”.:.enj_'eaicCL Ll Ice C.) for Thirty v: r'. \ C; e cud — -~ _ [V _ u "'. _ .1 J. ‘ P -n -':‘ -.._l.K cvt L4. -wiLmJC‘L‘LLLLL‘c O- luuo Iinutes. F. ( a A ." ‘ - U0 GU Acid Gas :0. Acid GE; 8 L00 H H l—J ~15 C! N O O) 6-3 :0 C: ‘Q C11 (13 ... _. "on -- _. _. #6 ._ .. _. a9 1h .. _. UO ‘— _. — Uu —. _. _. 54 ._ ._ ._ 55 ._ _. _. $6 .— .. ._ Q7 _. _. L. 33 -f- _. ._ 39 .— 100 101 r\ (‘1 UL} ~_. N'J. 7 7 0 1 ".. A n I. - t by.) 1U J .1.» z 1*: ) lb 1 4 1 4 1 «~- A O Q F f o q H‘ r‘ . ”‘1 r I o q ‘ D H ‘ ' MO 0 nClLL ch~b AC]. L Lu...) 4*. '5‘. u -LClCL mt...) {LC-L‘A- Uub b\3 _ - _ — - _ _ — _ F» a A LLU _ _ _ - — — - - _ CO _ _ — _ — - — - — _ H 4-;LV6‘ VI. T'WT ' 1r ~. .- - .1... -:~ .lfluili ~‘ 1rA-~.' v- ILL .LIL --i4LC1II . ., . . a Li)... tum», 0._ .4 ,- k/\-L..-- U‘LLJ. C 1&0 o L j 'I ‘ -L[ “ A. n 'V C - b . l.» .. l‘ rw'. _ .Lch .~4_ .P\-. JJ. DU. . 7.1 LVL‘Q‘g .L wLJQ i”. f‘l ‘ ' .. ‘ . . "' ' .~. '_ ' 3. 4 ‘ I... ‘ ‘ ”I 10 _ , O J. ”i. 1 I.” a“ . .. _ ,_, -44. ‘ C» u 0-; 14L; 11‘... ,lli L“. (-L - 55.-.»; ~'.;. :1 J. L‘;.'- L23... li"£i'.vJ.‘L'v pix :3 ' ~ ‘ ' 1| ”" .' - ".l . 14‘ J- 5 ‘ . ...I t, .. ‘1. J) --'\/‘ L. ,.-’~4 Cu "L: ‘J- l. --A u;.L \-' .L s.‘ ‘4' v-“./ \r .J ". L.-. L'._ \J st» 0... 5.. ‘vu .L‘O \Q‘e C; L) z» ‘_..V - J --.4- D ' - ’1 '1‘} 3A.. 7" ' J _, ““.. $- "A ULDE‘.» LLti C Q..— l‘ZDO g . (DUO U C) .1. LA. .-I AJ-l— U‘. — .J—‘A‘UL Lab b . -. . . ’0. ‘ 1U I 1.“. J 1‘; J I I I . _. ‘- . 9 . . - I", ’ -. v I p.. ‘- J‘.‘ O . 4‘50 i \L _ L-t S ‘&C l L‘- ‘w \‘V S .fi‘o L l k -4 51- L.) r‘r-X UV — — — - — — . (’4‘ V - — — — _ — U7 - — — — — — 1' ‘2) w + - 1" - ‘7“ - ' 9 U _ — - ~ — — The Ljfect of Licatigici I'e...be- ' T - m .-.-~ ---.... J ‘1 .- _.L ,, 1.11 .LCU uibgflh ._.L..m any .;:.l‘luu..: 14cc F lééo F h . .“ d. _ . to F. 1450 :. 147° ;. LO. nClQ Gus Leia Gas nciu Gas Leia gas gain was 18 + f“ 7" + 7‘" .. + _. .. _ 19 fiP 'f- 1P' 1” #L' 4L 1P _. _. ._ 58 1+ .. 1P ._ ~f— _. 7P- _. 7F _. a9 1* _. . 1? -+- 1F' _. 1” .. 1» ._ 40 7" _ + 7“ 7" _. + _ + _ 60 7" _ + _ + .. 7— .. +— .— 101 -f' 1“ HF- _. 1b _. -f- .. 1P- ._ 105 + _ 1" +' ~f- _ +- _ 1- .. Con ... _. .. ... .. _ .. _ _ ... F" u fi'w ‘3 ll“ . ghr' ILcn Lumbers of the =u 'n Ice Cream Iix at a The Effect 0 - - 0 6C. v lébo F. 61.60 C.) for Shirt: Linutes. Colon-across Temgerature O f3 *1 H; (D C. r *3 6 '0‘ 7S l: ‘m;“ 15:11.)“‘8 7v - y t ‘ *v _ ~ ,. . -: N. ‘ . _‘ - -’ .— MO 0 Adlu. vac.» “OLD. Ludo “Lib. 219.5 18 _. _. _. 1F- 19 1L uQ u? H O H nn$+++l II I +$$ l C01 .‘V f LU. Discussion The data submitted hes provided eohe interesting facts which should iOVG use1ul in inte; 116? in the s'hnif ic ince of members of the colon-aerOEenes group in ice 0 cum. :he com- u. peris on of he effect on viability yroduced oy sLim milk end by ice cream indicated definitely thet the letter exhibited a greater erot;ctive action. The tes tin: of the ingredients contributed very little to a solution of the problem as a thole. Cf all the substances AJ teste fet V.ss the one fro; thich a greater pro+ ective ection was expected. The hes. ti;;; of the cultures in feet c‘socnsions shoted greet \&Plublllhv, hovever, the OIg¢LlSLS tere readily killed then heated at a tehgerdture ~f 143° F. (62.80 C.) for thirty minutes. The data sho .s 10 influence of concentreticn of fat upon viability. Heating culture in shim nilk ponder shorcd no correla- tion between concentration end viability. The cultures sur- vivih; e tealereture of 140° F. (60° C.) then hee ed in shim J 1.- milk pomder mere he LQLS cultures SUPViVlLQ that tenpereture then heated in skim milk. Also three of these cult u_cs sur- vived in ice creeh mix at the sshe temgerature. Cultures heated in sucrose solutions sho Led variation in viability, but e;£.in no correlation \i ‘.s Deserve d between this effect and concentr.;:tion o.~ the solution used. Geletin mes tie one in redieit tested VhiCh enhibited the least protectite effect at the concentration used (0.5;). The lowest tehyereture adepted, 140° F., hes suffiCiBLt tO 1111 __ t—____—_.. g._-____4 __ t4 e lIile‘eC ients i 1di- viduslljl eihioite d no hurled effect on viability, the nent step vould huVe been to test vdrioos cozbin; tions of in- "D. 4.‘ h, gredients in an effort to 111 C the 1uctor or factors . w a resbonsiolc nor the protective action observed. Lh1o1tuhste ly, leek of ti1c did not 1er1it consider“tion of this phase of the problem. The nirLed effect eruioited by age of culture mes found to be in accord 11th yrevious torl of this nature. Thus Robertson (1;) found thst young cells mere Lore suscegtible than older cells to the action of high ten; rslures. He con- cluded that the most eff icinet pasteurization vould be obtain- ed if the heet Les Qi1lied before the bacteria had tassed the fi accelerotive eta-,-L (L3 of Crouth. The variations and egpsrent incensistenc ies were not entirely unexpected since other voriers have found similar vsriztions. Agers hLu HOh 1son (7) studied 174 cultures of Escherichia coli and found the fell tin; variations: At a temoereture of 140° F. (62.80 C.) 12 cultures survived the first trial. On retestini th Q found four cultures su rviving the second trial, ei ht surviving the third rial, six sur- .L vivinf 11s fourth trial, nine surviving the fifth trial, and no cultures surviving the sixth trial. The litnus Lilk tube sethod mes enployed. The authors concluded that a texgera- ture of l50° F. (65.50 C.) for thirty minutes should des troy nenbers of the colon-sero enes groun \he; heated in silk. If ns it nould not it is connon for milk o show hurled vuiiet i (\ r, y. 1* .—.~ Qi..v~_L._L b.g£~.-bl ~ . ‘ ., .4» y 1. ..—4 m \-+-. -‘-“, Q40.64 Una LGlmulQhoulg metuuu4 Viscoziu¢ aha bk) 0 J o _ - _ _ , .. _ It ‘ '~ .‘ i C‘ .4. r r‘ '71 U 10:; c-'u;l-1.1 Iiilo‘ inotilgi (444141» c‘vbli vutsfiog of :3 u4C oibt M V is closely linked \ith I k .5 I. ‘ ‘ .1 I . ‘3. ‘l‘ 'V . 4' . an |Au+ 7": v;- icccrc44i_ o C02w1l (1t, ) L041MMLliy l‘ a41xu,uui b; x " F“ ;, J"; ,4 . .AH " I" j" ‘ —, ._- lri LE‘“. -éL‘Q 4uctkfi‘. u-VWLw Uta i1”.~ Labiulv to CO“- - :ii .-.4 Hi. . - - _.“ “A 3‘. hA‘kfi-L‘Lj louL¢:.LO A‘ov Cbi.ul Vl‘ Ali-.). *,L'\.—a ; l"- ‘|.‘;Cll ELCrLu .-,- ~ . . 2. , ‘ ~. Viw- rw ., 44-... $10. 1‘. L.-L.<31‘L,o 3:: '4 Lip-c; :4563 in ‘4. mus ' J . - a“ - J- t. ‘ ,- 4-9 . r: r) -1 4‘ - 4 ~.— ‘9 . 1:“ . Lo .L' 11-4; .- 'uO LLVC u. 1).. Cf Uou , '- uvikfiflé C... tbl" ~ .. V 3-! 0 J4 o' v . J ‘ ‘ - ‘ " 1“ -0 ‘ . _' . ‘ , -. . .’ .... ,_V A..:; -.Clka.l.l> L~—ll..L \azLC 1)-- i;(.4.\~ OJ. t94¢ Kd.‘ C’;'£"Vu_ L] .U 0 - ,.:_~ 4.‘ ,.: ,,.:.:.\: 2. in +L:_- n 4_\_, J ‘. ~ LlC;$A ‘3; 5-;-‘..2‘ KJ‘.:: L‘A... —C\—3c‘cb 0*. L;Li “ J— . 30 iv ’5)" ....Oula , $ - - ' ‘ n in IrzLe iyvblmu LA itggli. A 4‘ 4.4 ..-1- , w _ 3-..”: 1.. fl * .‘ . C4 Ls“; 0-;L-Dt‘ELl.C&.llL-‘ CLLExl‘flCi b6- LiuglCS CI. 108 C. 65.13; ‘r ‘ J». ..- D“.L..~e Ullut H (I O O U) P. c?- .“ H d" I‘) (-h. C". fr ‘1‘ 0‘ {‘1 (f (3 t 1 t (_l H '.L (.L :1 ( 1 . .' J , '.. . J. ,_ 4.‘ . 1..i.:_--.L- L.-LV< J LJCLC’ ll-.LlLu;iLCC‘ 01; Luis r . . _ x .‘ ‘ t. C. if; 1. v U K 0.3;- (1;; O F? H a 0—) :3 \L‘ T (J kw lCELt (’1 ‘- ,n ‘ “ ~ 4.1“ '.. i o ’ ‘,. u.’_- _. ‘ o -_ “ 43:; LOLLLL; szi c...i inc-ragga: 1;; ti c3051.;d 0‘ ult- aci' reduces th ret rdation 0' heat pone- -. rm- 4. y- __ , - - :; iQCucz'14Lich lvdsjllitld 5441 ficurce Lu’l Qer '41.}, n-. V. -. ax -.‘34'v . ’ A - V, -.4.‘ . , .’: 2.;. \ lLLh—L ‘.. J.\-:‘;.AJ ’ Lil A- J L)»: 0.... 1.1 i“ 4'. L'C.J.lce 1.51 {I‘LL} COLJ.LLI‘- f'“ --., ‘ +—-. ' r 1 .. f' .. “usu- LU whine"; t;.61’1..c-zl ueattu O 1 I 7“ - 'actcria in various Lpul&o :40 \or \ L&S sumuzriz ed "The therg&l Caa tii point, deterniiea in bouillon Ufia ion-sue; e be ri 151Lctcria (iiclidiig EschericLia l ’A I“ O ’1 I .l f' ‘ H - a 'y . V ‘ . .I ’ ‘Q \ flavqu 1); 81:81.11 iZ‘J'u. 1.1 4‘- CALLS. U- 6a.. i lb 1Al|~_ liUl tLL‘CLll Cl. '11" eur1"1t101 tengeratl1e (145° 1. for 20 min.), while d- }. ‘ ...J (I) ’U & cr- uany have a tirirt.l death point beloL tin: temgerature of’ pasteurization. Tne casein an; fat in sill offer some protection to bacteria that are subiectea to hi h temperature during the Ce tn poilt detensination." It is impossible to J-‘ ,~ r. -‘ 1-“ , * '4-1 4w, 1.1 .. cougar me a:1ta secures ov J‘iiu ans leiser Nle tnat SuOLn 2 above, since a heating period of ttenty ninetes was used by the former ans a period of thirty ninutes for the latter tork. The fact that ice cream mix does possess considerable protective action for Lembers of the colon-aerogenes group is significant. Thus it is reas0nable to assume that tLis gro- tectisn 1ight be accorced to ot er tro as of bacteria. if this as Un/thu is correct it is evident that a tenperature of 145° F. (62.80 C.) cannot effectively pasteurize ice cream A recent article by Irice (lS) discussed the sig- P“ nificance of Escherichia coli in ice cream. 1ne author stated that the presence of the colon-aerogenes group in ice cream does not necessarily indicate fecal contamination. And 4- further, "Coxs an; other aninals are not susceptible b0 tyghoid fever and other enter'c diseases of nan; therefore, Bact. coli of bovine origin are tithoxt significance as far ‘ as transniss ion 01 such diseases is concer nea. Tne naneroas recor ed outbreaks of t; 11hoid and pa1at31101o.t12u1 1itted by milk supplies are conclusive evidence of their contamination from huran sources. ...... In co_mon 1ith other bacteria menbers of this group are LOTG indicative of the temperature at xiiiclx the will: has been Lest than 01’ original contamination.” «1-5;. '1 1‘ . ._ , . "‘ J " .. T LOU-J.“ '..;‘i)‘J‘-J.. l).:.. 1.-. colon-aerogenes gross lOse Most 01 found in c irg :r ducts The presence of t colon-a ‘y\ ' - ’V ’0 +‘ ' A-b‘JUl‘b O; LLLe their significance then erogenes group in ice cream could hardly be in ergreted as iniicatih inefficient pasteurization inas ush as resistant strains have b=en 1oana to be 001111011. The one other factor of interest 11:11.1- 3' that 9 9 of contamination after n1steu~1 e ion is one thich should be given due consider tion. lrobably the host COHJCU Boui 08 of CQLttifiJLLthM of‘ iris type ixizfron thr lxnxis 01 olmnfia tors. The gossibility of tni sorrce of 3s herichia coli mas recoinizsd by Kinsl v (LC) as early as 190?. A LOPG recent article by Buice, Behested, bade on 251 food handlers. Chev tota nnyber sh0iin; lactose f and Die: found 67.7 e1nie11tizn; (Ll) re" :27 4. L st C} b is": per cent of the aerobes. 37021113111111? 0 \ith Kos=r's sodium citrate lediun, 8.é yer ce1t of the total proved to be of intestinal or gin. 01053 attention to person- al hygiene noel; €11.1n.;e this factor as one of ingortance. The era available at the + indicate that too unch significance colon-aeroflenes grou; then of thi” 1roLJ and not blace too sac ". 4.11. ‘ V .1 -‘ - . ., ......1 - 1- n as t 1111111111 1‘11? sa1 itar 31,414.11 t; 01 found in ice cream. 1;) - shoila I'E'fiCOélliZC‘ t e li1 itatims :L LL61 )ClJ-CLLLLCB r‘ (.1. ~ 1 ‘ .. 1 1 . -1 '31‘1 w shoals not oe ccorsee the r” 1 Lealtli Of- of the test for members ubon it in cairg Lroaucts. r" .‘ 1,- 1.11.11.11.1111‘2; O l. A temg’rnt re of lsSO T. (66.80 C.) ta: focus necessary (‘1 to kill forty—tmo cultxres ”f thg colon-aerogenes gr~up then ninntes. re: a commer- heated in ice crean nix for .hirt Ci&l e sn‘poin; a tewgcrgtnre of lJCO P. (bo.o C.) for ‘ \ .1 v minutes was indicnten for nu pasteurization of ice CI‘GSJLI 1.11.}; o "I 2 ‘ ... \H-‘x'w‘r‘ ‘ - .,r|.-.‘ r- ‘ -. air. . . q? .! .'. 2‘ s. -ne sens Ch11u£6 11cn ne1tsa in snin L111 reluirec a teu;eratnre of only léJO F. (62.80 C.) to effect their death. F? n‘ ‘-" '5” . w . \ n . ‘ fl . x" ‘ ‘ 'L ('\ - ‘ . ‘ .- 'w ‘5." “ 9 - --« " 1' ‘1' . r f} -‘ U o -118 (”1110111. 11L: I Chloi1 '10 €--€‘~...lll'\, LL , ;.\,-.._1’;,’ 1“. , C Clu. L 11L, cream, "r'. ° ‘1 _ ..r - . r 1... H ,, .‘ . ,p- - _1 - , ...; . 4— 1‘1- 81111.; 1.1.1.11- l’O\1U.€‘f, 5‘.--U1 SLI_C.~ 0-1.6 fc~ll§¢k~ to k--LO\ INK... J-C\J. E110 bee bl‘se action on vinbilitg. A ten1eratnre of 140° F. (60° C.) killed 8 '9 > “'1‘ - ". . ,1 .4—:.- . . . .- 02—“9 J- ‘- ....1 .—-\. » ~4- sli 011, run in L,el:1-.11:1 :hll: one other 11 renicn 1s regnired a ten;eretnre of léSO ?. 1&2.8° C.). r'f‘~"_ .001) 4. ‘10 , , p ..‘11‘ .4 , -1 gr}. 1- .n . . é. 1ne e11s01 o1 1.e 01 c 11n1e on tne V1111l1tc o1 tlLLt +1 v. 1‘ . :"v ‘n " ‘ 14“ ' .1 ' ' 'k‘ ’fi- .14 {a -' :‘I‘ A“ ‘V q, . ' ctralhu o1 tnc colon-acro ones t_ronp Les nc1crn1nco. 1t 11s .0 1on1; tlnt all strains :ere lillel at n tengeretnre o ’1) '._J s MJ f. s § — t A . 0 v , A ' r _ 4-;- _ a 0 fl V I .1 _ u . ‘fi ‘ _ (U100 Co) 3.11131- hue-.1191... 111 10:; 07365.13. 1.111. 11.2.3114; Ouitul‘Gb El" 11 0111's 0111 . , “14.1.6 - -. 1 1 ~11. ._ , ~ ,.. ,- - 1. xeno;-1Onr nour on11nres nsntcu onus? Slnllir 00n- 1: :“m‘ ‘ 'xw ~‘ (~“’ r. 1' .0 r. -.\.- ’ . (1113113111; SAULCL C. lLLl‘Nqul 0.1. 7..) .161" CULU. C:1.c--1.;10:‘.s . --l ‘.‘_ ,- :- J', ”1.. ,, ,. .,_- '. ‘ J . lo .' 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A. .Lllmfiun, yr. ;LQ ulltncr, glib. ..Jl'o u. .ut‘JCl‘ellX. w' 0 i ’I ‘4 9. .. 7‘ __‘ , C' ;, .,. .A a v _ -‘u'vr‘. JL'V;-CLHO - .-.. I ‘V .‘ r-~ ‘ .' ’ I1 , J. .. V ‘V ~. ... .' . '- xi' ,. n “ _‘ JOlokLul/l , ...: o C‘ 0 ’ ..--C .. '3‘ LC LIL} J : I.‘1.‘.A.LLL\.~JJ.LU (JJ. .J 0 CU; 92?.) ~ :~-. ‘-.. O ..-. I‘ _,i __‘ ’!° N 8.11 lL1-_c_- 0.. tel; i;L«.-'illC- T, -. ,3 fr- -, __- .' ,4 l .'_ C- ”‘ 1'- il odulo --‘blpl-b, ’ L.«J. EL 0 b :\ ‘_ ~r - .'u . . ‘ c 1’.- " ',-. o -3 o o <" u |-’. ' .. ’ " qug'wfii, "a v0, ulC,L1l...lC:~liCU OJ. 4. 0011 11;. Lil'ligt..l-i(_s yutbro fi 71" . ‘ r, K , I F". ‘ 1 1- q t‘. o “‘1 _' o. " Lofigvh, __,. #1., --.;[J (304.011 DcClllL-m 141 t \ "til. \47.’ port}. H Joor. ngieze, 5, lUS. lEOb. Ltcoghton, 3., Clerectcristics of tle colon bzcilli and valge of tne Lyceumptive test. Jour. Inf. Tiseases, Lupgleb;nt z, 1&7. 1:05. 5,- ” - "... "r r 7‘ ' .. “, . ... 'i' T raw, A) . 1 .’ .‘ -5 - . . .1" ol bacteria. JOLLI'. -UCLLCEJ. :LUSO 19’ 1.7:), ...-LEGS. a Shippen, L. 1., Significance of 3. coli in pasteurizec 11 J..l F4. ’1 H ‘ I -L Joor. Am. )edical Assoc., 64, 1&89-91, 1915. ' Ayers, 3. h., end Johnson, I. T., Ability of bacilli to survive pasteurization. Joer. Abr'l Research, 5, éOl-lO, 1915. 33ers, 3. 3., and Johncon, u. T., Studies in pasteurization. ‘ ‘ n - r] . .: If :: I .:. .r‘. '7' ; . A r. Ol quto v 9, ~Ju-99, he» 19u%o ”I Jeniins, 1., prerizents on the pasteurization of milk. 10. ll. 15. ‘4 C1 0 17. r- cf. ”1.- .- J... "A . ‘ ,- ' i.) ‘1 ( . :,_ ,- . 0 i1, p\.ehazrum;, J., pen -). C\_.ll Lu, ..Loztl Lb .-.]; line. C- 1,4-8 0‘? - (-4- .' ' 1'8" ' prover LuSLChPlZflthu oi hllL Jocr. of fict., v 13, June l917. ‘ ' u. 1 r” K‘ .- .- . -. . ., . -. . - V; ‘ 4 - o. - r. z . 4 7‘ _" _‘ 4‘ 0' ’— -1 ’ ' — route, C. 9., otLe euLLcetioie 1n esoiic the Leenoero metuccs 0 Ag. Jo r. of Iublic Ice th, 17 loge-e, 19:7. Euclizn, G. I"., Co::t::~~.::-.iz;:;tio:1 of ice cem. JLur. Iggiene, 10, 25-105. 1904. 3331113111. J. 5411‘; Kerr‘s, L. S. Co:.-.,-,.>:..i"is.ron of rethods .n . '1._,¢.,_.,._ - , - ~ ,, 1.-- ,- ,._. ,_ _‘-.. '1 ~4 ior QueuldlnlAk tum Suflltuw“ caiiu fl oi ice cream. 50 r. Lair: 30- 11. 234-91, 19:3. Lolloff, A. 3., A Si ply synthetic medium fer the cultivation cf bacteria. SCISLCG, ;l:to 10’ 19:60 V. 63, p. 29%. gobertson, 5. L., fifect of are of Cull re on heat . ' 4...- ”3ng bLLl'lCe o Vereont Agr'l ngt. Ztetizn Bulletin L75. Cohen, 3. ;-fecte cf terperzture and 32 on the viability o; J. ccli. Jotr. :act. 7, 185 92:. Joslyn, T. A., ;ole of viscositg in heat ,enetration. Fruit lrccucts JOurEal: day lELB' 18. Bromn. C. 1., anu Peiser, 1. A s ua; of tne factors which influence the resistance of lactic acid bacteria to ‘Lleat o Iich. Agr'l ont. Station technical Julletin 00. 19. Irice, L. 1., Zhut of sect. coli in ice cream? ‘IV Greater: enu iilk Elent Tonthly, Vec. 1828. :0. Uinslax, C. 3., Occurrence of 3. coli on the hands. Jour. o; fedical Lesearch, lO, Q65. 1905. El. Buice, L. A., Sehesteu, H. C., anu Lieret, “ ‘ Occurrence of B. coli on the henus of food norulers. L~-4 Jour. Inf. Diseases, e0 (2) ze8-Lol, lSzV. wilfflll...‘ ..I.4..1.. .Jflyttki ..K .1444. .1. 'LI'I,E§JJ .... ...r Ir y»: .\iu.\~.k\‘\ ul\\.\ V\. II: lil.1‘11 \ 11.014. _‘VI VJ . .12..”,rluauya.cl!....€-¢? in; . ‘ .rm-‘z- fm'u‘iil'n' 03046 85 0 U“ V" T" m" R” E" V” 29qu 3 IIHIHNIWIIIHIHI