Camembert cheese was made from pasteurized milk contaminated with about 102–103 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 107/g when ripening was almost completed. Growth of Hafnia sp. during the storage period coincided with an increase in pH of the cheese.

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