The low-temperature, long-time cooking of beef, using either a water bath or a conventional oven, resulted in partial inactivation of Clostridium perfringens vegetative cells. Beef roasts were cooked in a water bath for process times calculated to inactivate low and high levels of C. perfringens vegetative cells. Cooking beef in a water bath to an internal temperature of 60 C and holding for at least 12 min, as required by the USDA, reduced a population of C. perfringens by approximately 3 log cycles. To decrease the risk of subsequent outgrowth of C. perfringens, roasts (⩽ 1.5 kg) may be subjected to a process calculated for a 12-log reduction in population, which would include holding times of 2.3 h or longer at an internal temperature of 60 C. Recommendations are given for cooking and cooling roasts to minimize microbiological problems.
1Present address of A.M. Smith, formerly A.M. Hickey: Department of Foods and Nutrition, University of Illinois, Urbana, Illinois 61801.