Cottage-type cheese samples were examined using specialized media. Nine media were used to provide 21 different types of information and to enumerate bacteria able to excrete lipases, proteases, phosphatases, and acids. Further, these media allow subdivision of the bacteria with specific enzymic attributes into gram negative and positive categories and pseudomonads. A yeast and mold count and a test of those able to grow on violet red bile agar also were made. Tests most useful as predictors of keeping quality were primarily those able to differentiate proteolytic and lipolytic gram negative bacteria and pseudomonads, Microbial tests were also correlated with organoleptic analysis. Manufacturers' code dates (last day of sale) overestimated shelf life about 33% of the time.

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Author notes

1Department of Biochemistry

2Department of Ecology

3Dairy Division