The causes of acid liquefaction in a high grade pasteurized milk were investigated.
1. Liquefying milk produced much less acid and had a much lower plate count than normal milk.
2. <i>Bacillus albolactis</i> was found regularly in the milk. It made up a much larger percentage of the total flora in liquefying than in normal milk.
3. Associated growth experiments showed that <i>Strep. lactis</i> could control the liquefying activities of <i>Bacillus albolactis</i>.
4. Pasteurization experiments showed that milk heated for 20 minutes at temperatures higher than 61°C. would undergo acid liquefaction. This appeared to be due to the increase in the percentage of <i>Bacillus albolactis</i>.
5. Inoculation of pasteurized samples with <i>Strep. lactis</i> prevented acid liquefaction.
6. Comparison with a type species showed that the strains of <i>Strep. lactis</i> repeatedly isolated from the milk studied were of the <i>tardus</i> variety.
7. The liquefaction was probably primarily due to an increased percentage of <i>Bacillus albolactis</i> brought about by pasteurization; the lack of the type of species of <i>Strep. lactis</i> and the absence of lactobacilli might also have been contributing factors. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/53492 |
| Date | January 1938 |
| Creators | Rubin, Benjamin Arnold |
| Contributors | Biology |
| Publisher | Virginia Agricultural and Mechanical College and Polytechnic Institute |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | en_US |
| Detected Language | English |
| Type | Thesis, Text |
| Format | 47 leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 29450501 |
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