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Behavior of Enterobacter aerogenes and Hafnia Species During the Manufacture and Ripening of Camembert Cheese

Rutzinski, J. L., Marth, E. H., Olson, J. L.
Journal of food protection 1979 v.42 no.10 pp. 790-793
Camembert cheese, Enterobacter aerogenes, Hafnia, agar, bile, coliform bacteria, manufacturing, most probable number technique, pH, pasteurized milk, ripening, starter cultures, storage time
Camembert cheese was made from pasteurized milk contaminated with about 10(2)–10(3) cells of Enterobacter aerogenes or Hafnia sp. The coliform bacteria were enumerated with a Most Probable Number procedure and with violet red bile agar. Numbers of viable E. aerogenes decreased rapidly during ripening at 15.5 or 10 C when cheese was made with the commercial lactic starter cultures OD or C-5. No viable E. aerogenes was detected in cheese ripened at 10 C for 3 weeks. Ripening of cheese, made with starter culture OD or C-5, for 1 week at 15.5 C was accompanied by a decrease in numbers of viable Hafnia sp. to 10/g. The number of Hafnia sp. increased markedly during 7 weeks of further ripening at 10 C to yield cheese which contained numbers in excess of 10(7)/g when ripening was almost completed. Growth of Hafnia sp. during the storage period coincided with an increase in pH of the cheese.