Haneklaus, Ashley (2009-05). Evaluation of Alternative Cooking and Cooling Procedures for Large, Intact Meat Products to Achieve Lethality and Stabilization Microbiological Performance Standards. Master's Thesis.
Thesis
This study was conducted to determine if alternative heating times and slower cooling times, other than those defined by FSIS, could be utilized and still comply with FSIS performance standards. Large (10.43 to 12.25 kg), cured bone-in hams (n = 190) and large (greater than or equal to 9.07 kg), uncured beef inside rounds (n = 180) were utilized in a two-phase study. Phase 1 of the study investigated the effect of alternative lethality parameters on toxin production of Staphylococcus aureus and log reduction of Salmonella Typhimurium and coliforms. Both the hams and roast beef were subjected to 1 of 10 treatments defined by varying final internal product temperatures (48.9 degrees C, 54.4 degrees C, 60.0 degrees C, 65.6 degrees C, or 71.1 degrees C) and smokehouse relative humidities (50% or 90%). Phase 2 investigated the effect of alternative stabilization parameters on log growth of Clostridium perfringens. Stabilization treatments extended the times taken to reduce internal product temperature from 54.4 degrees C to 26.7 degrees C and from 26.7 degrees C to 7.2 degrees C (ham) or 4.5 degrees C (beef), independently. Further, a control treatment following current FSIS, Appendix B guidelines was conducted for ham, and a "worst case" scenario was assessed for both products. The "worst case" treatment evaluated the effects of cooling products at room temperature (approximately 22.8 degrees C) in place of normal cooling procedures in a temperature controlled environment. Results of the study showed at least a 6.5-log10 reduction in S. Typhimurium across all lethality treatments for both products. Further, coliform counts also were reduced significantly, and S. aureus toxin kits returned negative results for toxin production for all treatments of ham and roast beef. Stabilization showed less than 1-log growth of C. perfringens for any treatment, with the exception of the "worst case" scenario for roast beef. As expected, > 1 log growth of C. perfringens was found for uncured roast beef maintained at room temperature for cooling. This study supports that there are multiple time and temperature combinations, other than those currently provided by FSIS, which may be utilized for cooking and cooling large roast beef and bone-in ham products while still meeting FSIS lethality and stabilization microbiological performance standards.
