| Abstrakt: |
The suitability of handling practices used in school kitchens was evaluated using ground beef gravy that was contaminated with Clostridium perfringens. Cooked gravy was cooled to 110 F (43.5 C) and inoculated with a mixture of vegetative cells and spores of C. perfringensNCTC 8239 to provide approximately 10,000 organisms/g. After inoculation, gravy was packed in bags, refrigerated for 16 h, held for 5 h at 82 F (28 C) or 42 F (5.5 C), and then heated in a compartment steamer for 35 min or until the temperature of the gravy at the center of the pan reached 165 F (74 C). C. perfringenswas enumerated at intervals during cooling, holding, and heating of the gravy. The number of viable cells after 16 h of refrigeration at 42 F (5.5 C) was influenced by the first 6 h of cooling when the temperature of the gravy was in the range that permitted growth of C. perfringens(65–122 F; 18.5–50 C). Plate counts of gravy held for 5 h at 82 F (28 C) or 42 F (5.5 C) indicated stablization of the C. perfringenspopulation. When 165 F (74 C) was the final temperature to which the gravy was heated, no viable cells of C. perfringenswere found. |
