Growth of Listeria monocytogenes and Clostridium sporogenes in cottage cheese in modified atmosphere packaging.
1993
Chen J.H. | Hotchkiss J.H.
Low fat cottage cheese (pH 5.14) was inoculated with three strains of Listeria monocytogenes, serotypes 1a and 4b, an isolate from a dairy processing plant, and Clostridium sporogenes ATCC 3584: The cheese was packaged with or without added dissolved CO2 in polystyrene tubs overwrapped with or without high barrier heat shrink film and stored at 4, 7, and 21 degrees C for up to 63 d. The concentration of CO2 in the container headspace was 35% (vol/vol). The CO2 concentration in that headspace declined by one-third over the 63 d of storage at 4 degrees C. Clostridium sporogenes failed to grow under any condition applied in this study. In the conventionally packaged cottage cheese, L. monocytogenes increased from 104 to 107 cfu/g after lag phases of 28 and 7 d at 4 and 7 degrees C, respectively. In contrast, L. monocytogenes failed to grow in cottage cheese packaged with CO2 and stored at 4 degrees C up to 63 d and increased from 104 to 105 cfu/g in products packaged with CO2 at 7 degrees C. These data suggest that the addition of CO2 to cottage cheese to extend shelf-life does not represent an increased Listeria or botulism hazard but that cottage cheese could be a vehicle for listeriosis.
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