Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1929 Some of the factors influencing the growth of molds in butter Harold Macy 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 Macy, Harold, "Some of the factors influencing the growth of molds in butter " (1929). Retrospective Theses and Dissertations. 14244. https://lib.dr.iastate.edu/rtd/14244 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 miaofilm 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. UTv/n scsis CP Tss PAC-TOHs ii.'PLUisciSG m: aso'sm 0? 2iOLI>£ in BUTTia 3y Harold Uiacj A !Eiesis Sabaitted to the Gradoate Pacolty for the Degree of DOCTOR OF PHILOSOPEI Hajor Sal)ject Dairy Bacteriology improved: Signature was redacted for privacy. In charge o^ &jor vovk Signature was redacted for privacy. H^d of Major' Departoieit Signature was redacted for privacy. Deaa of Graduate College lova State College 1929 UMl Number; DP14491 UMI UMI Microform DP14491 Copyright 2006 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. 60x1346 Ann Arbor, MI 48106-1346 lABLB OF COSTMTS Page Introdoction. l>3 Heriew of Literatare. 4-38 Factors Inflaenclag Qravth 5 Food Supply 6 Molstare, ..... 16 Atzaosphere 20 (Eecperatore 22 liiscellaneoas Chemical and Physical SaTironment 25 Species of 22olds Isolated, fron Battor. , . 35 Purpose of Study 39 Ilethod of Procedure 40-42 Species of Holds Used 40 liethods Saployed 41 Z5anner of Secording Hesolts 42 Szperiaental 45-147 A. Pood Sapply 44 1. Fats and Helated Substances 44 a. Fresh Batterfat 44 h. Old Batterfat 45 c. Batterfat froa Trashed Creaa. ... 47 d. Batterfat Washed with Alcohol. 51 e. Fresh Batterfat plos Water .... 53 f. Old Batterfat plos "ffater ..... 57 g. Alcohol-extracted Batterfat plos Water. ......... 57 h. 0.5;e Aoaeoas 3niil sion of Hilk Jiecithin. .......... 60 i. 0.^ Aqaeoos jSnolsiozi of Milk Leci'&.iii in 1.5^ Washed Agar .. 62' jm 1% Glycerol in 1.5;& Washed . 62 k. ITj Satyric Acid in 1.5^ Washed Agar 64 Page 1. Paloitic Acid in 1.5^ hashed &ear. 66 EX. Stearic Acid in 1.5^ TSaahed agar . 68 a. Oleic Acid in 1.5^ 'Sashed igar ... 71 Z. Proteins aid delated SoJ^stances. ...... 71 a. 1% Aqaeoas Solation of P^tone. .... 71 "b. Card Portion of Batter. ........ 75 c. 2>ialjzed Card froai Batter ....... 76 d. 'Bashicga fron Creaa 76 3. Carbohydrates and Belated Sobstances .... 78 a. 1^ Aqaeoas Solation of Lactose 78 1). 1^ Aqaeoas Solation.of Lactose in 1.5^ 7aslied .Agar. 80 c. l/a Lactic acid in 1.^ Vl^hed Agar. .. 83 d. IXLffasate froia Curd of Batter ..... 83 4. Mineral Salts. 87 a. Milk Ash. in 0.75^ Aqoeoos Solation.. 87 "b. iiiilk Ash in 0.75^ Aqaeoss Solation Seatralized with hydrochloric Acid . 89 5. Combinations of Tarioos foodstuffs SZ a. Scsalsion of Batterfat, Lecithin and l^ter. 92 13. Batterfat plas ]>ry Milk Ash 92 c. i^iztares of Batterfat, Milk Ash aod '^ater 94 d. Aqaeoas Solation of Lactose axid Peptone 97 e. Hiztore of iiactose and P^tone in 1.5^ hashed Agar 97 f. Sterile Unsalted Batter 99 B. Moistare. 103 1. Hoistore in Sa'bstrate 103 2. ^istare in Atoo^here 104 a. Effect of Hcuaiditj apon Growth of Holds on Uiisalted Batter 104 "b. isffect of Hamidily apon Growth of molds on Unsalted Batter Chtzmed froa Inoculated Cream. 106 C. Temperatare 107 1. Growth on iShey BrotJa. ............. 109 2. Growth on llhej igar 110 3. Gbrowth in Sweet Battensilk 112 4. Growth on Sterile Batter 115 5. Growth on Batter ^ade from Xnocolated Creaa. 117 I>. Atoosphere 121 1. 0rdlQaZ7 Air Supply 121 Page 2. Bedaced Mr Supply—Partial Tacaon 121 3. Partial RetroTOI. o£ Carbon Dioxide 122 4. SeaoTal of 0:^sea 124 £. Iliscellaneoas Chemical and Physical Factors 127 1. Salt 127 a. IQiey Broth, plus Salt 127 b. UShey plixs Salt 1^9 c. Sterile, Sveet BattezsdlJc plus Salt • . ISl d. Sterile, Soar Battermllk plos Salt. .. 1S3 e. Sterile Batter plus Salt. • 1S5 f. Sterile Batter plos Salt 159 g. Batter (I^e from Isocalated Cream} plos Salt. ...... 142 Piscassion of Sesolts. 148-170 A. ?ood Supply 148 3. I^oistore 159 C. Tes^eratore 162 D. Atoosx^ere. .... 163 S. Salt 165 F. Species of Molds. 168 Sasimaiy. .......... .171<.174 Acknovledgeneats 175 Bibliography ... ........ .176-191 SC3MB 0? !SHB 7kGT02S ISFUJISOJSG OHS GSO^ 0? MOLDS Ig jiU'Pl'Jiai IiraE03RJCTIC3ff xaarket value of "batter is deterained, in a large aeasare, "bj flavor and axoioa, bat the general e^pearance and ph/sicsJL stroctore also have considerable inflaence apon a critical and. discriminating buyer. CQae of the nost disturbing defects of market batter is dae to the growth of nolds iiiiich piodace discolored areas on the surface of the butter, wrapper or packing, often sufficiently serious to cause the rejection of sucix batter by the dealers. On the other hand, the laold growth may be such that there are no marked, visible signs of molding to oar the appearance of the batter bat quite enoa<^ to bring about decided, deleterious changes in the flavor and arona. 1!he dis­ coloration of the batter due to the growth of laolds is always a aerioas matter in itself, bat when the flavor and aroma may be affected sim- oltaneoosly, or even independently, as they are by the development of certain molds, the situation assumes veiy serious proportions. As a ^1. rule the market has been thinking of the molding of batter, principally, as a defect in appearance because this is the most striking manifeet- ation of the development of these microorganisms. Generally, suldy batter is encountered as an isolated ease. altho at times an oatbreak of aoldiness in batter from certain creaso- eries may asscune the proportions of an epidenic. "^en sack a sitoation arises, losses to the cr^aacries mannfaetaring sach batter are often heavy, involving hundreds ur tJioasands of dollars, quite safficient to eaase a aiaor financial crisis for large creaaeries, and a oajor crisis for sca.ll.er establishments. In recent ^ears, aoldjr batter has attract­ ed aiach acre attention thaji it did at one tinie. The reason for this is not entirely clear altho changes in the oanofactaring methods aiid a more discriminating market may be factors rhich have had a part in this increased interest. The appearance of mold in "oatter has been more frequent in ohsalted "batter, and occurs most commonly daring the early q>ring and summer months. Eovever, isolated oases ma^'- be encountered at any season of the year and in various grades of "batter and margarine. The mold problem is really serious for the creamery industry, considering the damage done b^- the mold in producing liie typical sur­ face discoloration and deterioration of the product. A number of in­ vestigators have interested tiieoselves in a study of some of the factors •which may influence the growth of the mold in the "butter, but there are a number of factors which have not "been studied carefully, and vhich oust "be understood clearly "before the industry may assume control of the situation. ?or instance, it has "been agreed, quite generaJ.l^'-, that salt has a preservative action in "butter and tends to prevent moldiness. IJevertheless, many cases of mold grovth in quite highly salted batter continae to occmr. Qie prolieia is not sifl5)le, nor will it be easy to solve. !Ehere are so oany possible factors vMch. oajr inflaence tiie grovtb. of molds in butter that each of them most be studied thorol/ before a proper eralaation of each of txiem can be made for iMiridoal species of molds and mixtores of species vhich mas' occar in a given, lot of batter. The relationships lehich these factors have, one to the other, mast be established before the problem can be approached td-th a reasonable degree of assurance that control can be exercised. fhe studies rex>orted here hare been undertaken in an attempt to provide farther data from ^diich fatare research may be directed toward a more complete solution of the problem. -4- HS7ISi- Q? LITSaATUiiS Diere is no iadicatioa in the literature as to tiie original o"bser7ation.