Thermal inactivation of Bacillus cereus and Clostridium perfringens vegetative cells and spores in pork luncheon roll

The aim of this study was to design a thermal treatment(s) for pork luncheon roll, which would destroy Bacillus cereus and Clostridium perfringens vegetative cells and spores. B. cereus and C perfringens vegetative and spore cocktails were used to inoculate luncheon meat. Samples were subjected to different temperatures and removal times. The decimal-reduction times (D-values) were calculated by linear regression analysis (D = -1/slope of a plot of log surviving cells versus time). The log(10) of the resulting D-values were plotted against their corresponding temperatures to calculate (-1/slope of the curve) the thermal resistance (z-values) of each cocktail. The D-values for vegetative cells ranged from 1 min (60 degrees C) to 33.2min (50 degrees C) for R cereus and from 0.9min (65 degrees C) to 16.3min (55 degrees C) for C perfringens. The D-values for B. cereus spores ranged from 2.0min (95 degrees C) to 32.1 min (85 degrees C) and from 2.2min (100 degrees C) to 34.2min (90 degrees C) for C perfringens. The z-values were calculated to be 6.6 and 8.5 degrees C for B. cereus vegetative and spores, respectively, and 7.8 and 8.4 degrees C for C. perfringens vegetative cells and spores, respectively. The D-values of B. cereus and C perfringens suggest that a mild cook of 70 degrees C for 12 s and 1.3 min would achieve a 6 log reduction of B. cereus and C perfringens vegetative cells, respectively. The equivalent reduction of B. cereus and C perfringens spores would require the pork luncheon meat to be heated for 36 s at 105 and 110 degrees C, respectively. The results of this study provide the thermal inactivation data necessary to design a cooking protocol for pork luncheon roll that would inactivate B. cereus and C perfringens vegetative cells and spores. The data may also be used in future risk assessment studies. (c) 2006 Elsevier Ltd. All rights reserved.