| The safety of beef and pork roasts that are vacuum packaged, then cooked, chilled and shipped in the same package was evaluated through cooking, chilling and storage challenge studies using Clostridium sporogenes and Clostridium perfringens. The microbial flora of commercially produced beef roast was also evaluated. Beef and pork were inoculated with 106 CFU/g C. sporogenes spores, vacuum packaged and cooked to 82.2°C with a dwell time of 7 h and 4 h, respectively, chilled to 4.4°C within 4 h, then stored at 4.4°C or 10°C for 150 d. Samples were tested for aerobic, anaerobic, and C. sporogenes counts every 30 d during storage. Cooking significantly reduced aerobic, anaerobic, and C. sporogenes counts from 4.07 to <1 Log CFU/g, 3.74 to <1 Log CFU/g, and 6.19 to 3.90 Log CFU/g, respectively for beef and from 3.49 to <1 Log CFU/g, 3.25 to <1 Log CFU/g, and 6.28 to 4.73 Log CFU/g, respectively for pork. Aerobic, anaerobic, or C. sporogenes counts did not change during storage for up to 150 d at 4.4°C or 10°C in cooked beef or pork.; Beef and pork were inoculated with C. perfringens NCTC 8238 (Hobbs serotype 2), NCTC 8239 (Hobbs serotype 3), and NCTC 10240, heated to 75°C, held at 75°C for 10 min, followed by chilling from 54.4°C to 26.6°C in 2 h and 26.6°C to 4.4°C in 5 h. This chilling resulted in an average log increase in C. perfringens of 0.52 and 0.68 in cooked beef and cooked pork, respectively. These log increases were well within the maximum of 1 log increase permitted by USDA.; The microbial flora of commercially produced vacuum packaged, fully cooked, beef roasts from 4 producers was determined. Broth from the roast and broth and cooked beef combined were evaluated for aerobic, anaerobic, and lactic acid bacteria and clostridium type organisms. No organisms were found in the broth. Broth and beef had <2 CFU/g est. This would indicate that the cooking and chilling protocols used limited survival and outgrowth of the microorganisms evaluated in this study. |
