Microbiological analyses were performed on samples taken at various stages of processing of 17 vats of cottage cheese manufactured in 12 commercial plants. In 10 vats of fresh cheese whose shelf-life ranged from 5 to 10 days, the logarithmic averages of the counts of coliform, lipolytic and proteolytic bacteria were 50, 1,298 and 1,967 percent greater than the corresponding averages of 7 vats whose shelf-life ranged from 13 to 16 days. Spoilage organisms were found in water, coagulator, starter, air, contaminated equipment and improperly pasteurized milk and cream. Several water supplies contained high populations of lipolytic and proteolytic organisms, but were free of coliform bacteria which are commonly used as an index of acceptability for water supplies.

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Author notes

1Mich. Ag. Exp. Sta. Journal Article No. 1904

Dr. L. G. Harmon received the B. S. degree from Kansas State College in 1936; the M. S. degree from Texas Technological College in 1940; and the Ph. D. degree in Dairy Bacteriology from Iowa State College in 1954. From 1936 to 1954 Dr. Harmon was a member of the Staff of the Dairy Department, Texas Technological College and served as Chairman of the Department in 1947–48. In 1954 he joined the staff of the Department of Dairy, Michigan State University where he presently is located.