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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A study of the causes of periodic abnormalities of a high grade pasteurized milk supply

Rubin, Benjamin Arnold January 1938 (has links)
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

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