Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1934 Causes of slow acid production in butter cultures Louis Albert Harriman Iowa State College Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agriculture Commons, and the Food Science Commons Recommended Citation Harriman, Louis Albert, "Causes of slow acid production in butter cultures " (1934). Retrospective Theses and Dissertations. 13705. https://lib.dr.iastate.edu/rtd/13705 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. 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ProQuest Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0600 NOTE TO USERS This reproduction is the best copy available. UMI* OATTSTIP op ST,or: ACID PRODUCTION ITT BTTT^I^IP nxn,'VT!V,V.9. BY L. A. HARRIMAN A Tliesls sTibmitted to tb.o ^rndunte Fanulty for the Degree of DOCTOR OP rHIT.OP>OPHY Major Subject Dniry Bacteriology Approved: Signature was redacted for privacy. Signature was redacted for privacy. Heart of Bin jor Department Signature was redacted for privacy. "ean of Sradiiatecollege Iowa Stpte College 1934 UMI Number: DP12739 (@) UMI UMI Microform DP12739 Copyright 2005 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, MI48106-1346 ••• •/ ""2 •" TABL^-' OF' OnTTTEHTr, PR I. INTRODTJflTIOW 4 II. STATI-m'INT OF PROBLEM 6 III. HISTOnCAL 7 A. Exflmples of slov,' sold production . * 7 B. Inflxience of the milk ixsed 9 C. CrerTTiloidpl property of the nilk used 9 D. Effect of hept on the germicidpl property ....... 11 E. Effect of abnormal inilk 12 P. Oontaminct ion 12 (5. BanteriophRfre and primitive forms . 14 H. Bsoterifil vsription 14 I. Bactcripl inhibition 16 IV. rrMERAL METHODS 18 < V. EXPKHIf/TJ'^MTAL 19 Part I. Effefit of milk nsed in mak­ ing butter cultures on the rate of acid production . 19 Section A. The effect of milk from vari­ ous herds end individual cov;s . 20 Section B. The effect of orc^anisms present in the milk ... 25 -3- Pnf^e Section C, Tlie effect of con- taminrtlon from plfint eqiilprnent ... 28 Pp.rt II. T'Jffent of the bntter onltnros used f)3 InopAilnting nmterlpl on the rate of acid production, 37 Section A. ExFiminetion of but­ ter cultures .... 38 Section B. Kxanlnation of bnc- terln free filtrntes from butter cultures. 50 Section 0. Atterripts to prodi.ice slov/ culttires ex- perlTnent filly .... 77 VI. DISOTTSniOTT OF RI'STJT.T? VII. COTICLTTSIorK 89 VIII. BiBLioanArHY 92 IX. ACK!TO'.VLEDai«i:T'TS 96 -4- IfTTHODTTOTION Bufctei' Gultnrcs'"'- eopietl'-es fB?l to procKtioo roid at n normal rnte Vv'hon Inoonlnted into nllk, nnd siich obnorrasl- ly slov/ acid prodnntion probably ooniirn v/herever butter ciil- turos are 'Jsod In the TnonnfnctTJre of ^ftiry products. Bntter ntiltiires \vbloh fpll to develop add nt the tisnal or oxpootod rote are n source of serious trouble in creameries nnd cbeose fpctorles In csusinj^ delays In routine schedu.les of opcrrtlon. Furthermore, If alow fjrov/ing cul­ tures pre Innubnted for RXtended periods, so the t e. normal arnount of acid is flnpllT/" produced, the cultures often show an undeslrpble flavor nnd body, which rriBy be ao ob.iectlonable thnt the culture is rejected. vVhen R slov/ growing culture is used in the manu- factiu?o of various prodiiots, difficulties often result be­ cause the normal chnnr^es do not occur. c^eneral plan of plant operation nay it very inconvenient to allov/ suf­ ficient time for the exnected changes to take plr-ce. ^!ore- over, if un^rsufilly lonp; periods are allowed, which niBy be necessary where procedures depend on the changes normnlly brought about by the culture, defects may develop which would no3?mally be restricted or prevented by a properly growing •»The term butter culture will bo used to reefer to the common type of culture so widely employed in the manufncture of butter, cheese, (artlficlol butter milk, etc* -5- culture« Theae defects my involve the flovor find arom or the •bod7r and textnre of the finished product. They mey he so pronounced as to catxso rejection end loss of the meterlal heinr? mnmxfoctured, or of tr^e finished product. One charaoteristlc of certain slow growing butter cultures Ib the rntber auddon or explosive manner Iti vfblch they ocnur. A culturo v.\py lie entix''el7J- nonnp.l in anpeerfince, yet B transfer of t'-:i8 culti^re may he alov/ In developing add. So for as 1-movm tViere Is no method of bacteriological, chemical or organoleptic examination by v/hich tho occiarrence of the difficulty can ho predicted, p,nd rn actual trial with the culture seena necessary/'. Ttiere are imdouhtedly various causes of slow acid production by butter cultures. Some of these are fairly easily determined, either b77 careful inspection of the Tnothods used In handling the o\,ilttu?es or by hMCt.oriological examina­ tion of the defective cultures. In other cases, hov/ever, such methods fail to disclose the cause of the slow acid produc­ tion, and tho rather unusual aspects of such cases have moti­ vated the v/ork heroin reported. -6- STATK!.T:TTT OP problem The investi5?Rtlon ves tmclertpken to determine the cansQ, or canaes, of the nhnormnlly slow odd production in certain buttor oulturoa. The results nre nrf^semted in two parts, as follov/s: Part I. Effect of the milk used in :nakinrs the butter cultm^e on the rate of acid production. Part II. Effoot of the butter cultitt'ss used as inoculating rnaterinl on the rfste of rcid prodiaction. -7- TTIP.TOKir!AL Itie literP-titro contfiinf. nany state^nents v/hicl\, of aif-piificjiriGe :1.n p oonsiderntion of KSIOVY ncid prodnotion in tetter cnltAires* Becnnse these aro "-ot all. closely re- Inted, the:/- nre diHcnssed in a minhor of sections. A, Jbcernples of slow acid, production. Several instyinoes of the elov; developinent of but­ ter cultures hnve been reported. Kniiclaen jmd ScJrenson (25) noted thrt sonc of the bcictoria ordinnrily fonnd in bxitter cultures grov.' very poor­ ly in sterilized aseptic milk, v/ith ncconipanylnr; feeble de­ velopment of loctic nairl. Yriitehep.d and Cox (40) used the term "non-acid" milk to describe tho milk In which butter ciiltwea gi'ev/ slow­ ly. Tliey gnve r method for determlnirif^ v/hcther or not a but­ ter oulturo vtIII develop nt f» normnl rpte in mnufactujflng processes; it consists essentially of deternininr; the rrrte at which pftsteurized milk inooun.fited v/ith the ctilture v/111 develop acid when incrbeted ft 37® C. Tl-iese v/orkers made the following statement! "The fnct has to be seceT)tod thst dif­ ferent starter culInures vnry in their power to produce acid not only as betv/een c^iltures bi^t PISO in sny one culture at different periods. Unfortunately, exa'n^nption of a ripe cul­ ture hy tciste, nronn or c^'^onionl nethcxls ciives no Indioeti.on of hov/ the atorter will pcrfortn '•n the cheese vat. Cultures whloh shov; exnctly the eeinie p.nldity v/hon rendy for nse and are Indlstlngxitshable In tnste and npomr may yot be entirely different ir; nction In tJie vat." Some of the factors sn^t^ested as censes of inhibi­ tion of Ifjotlc fomentation In t>ie rnamifpct^ire of cheeae y/ere studied by Leitoh (26), \vho eoiiclnded thnt slov/ ncid develop­ ment was not duo to cont«m!lnRtlon v.-itli ony one soecies of bncterip-, or to any property of fresh, rav/, noi'mal nilk. Moir (29) stated tbnt not much, is knov/n about the lo3f of vitality in cultures and listed sone of the possible oausec^^ na follows: "(1) Constantly over ripening the ctxl- tTiros, (2) Or,c;eniarns fron tT-ic sane pure culture may vary conaiderabl:/- in their ability to produce acid, (3) A strep- tooocctia Indistinf^tishable in nnpearance fro?7i a Icctic atrep- tococcus has been found actually to restrain acid develop­ ment, (4) Obacire abnormalities in the r,illk, and (5) Milks of low acidity." Vshitehead and Riddet (41) I'epox'ted a case of alov/ develonment in i^aJcinp: cheeae in v/hich two oi^ three hours over the norniBl time v/as required for the whey to roach an acidity of approxd-nntely 0,9 per cent.