Survival of Bacteria in Food Cooked by Microwave Oven, Conventional Oven and Slow Cookers ¹

To assess the destructive effect of different cookery methods on bacteria, strains of Escherichia coli , Clostridium perfringens , Streptococcus faecalis and Staphylococcus aureus were used to inoculate a meatloaf preparation. After inoculation, a sample was withdrawn for bacterial analysis and the remainder of the meatloaf was divided and cooked by microwave oven, conventional oven and slow cooker. The temperature of the meatloaf was recorded at various locations immediately after cooking to obtain minimum, maximum and mean temperatures for each loaf. Also, just after cooking, representative samples were taken and analyzed by conventional means for the specific bacteria and for total bacterial content. Survival percentages were calculated and plotted against temperature for each cooking method. Temperature variation within the loaf was greatest for those cooked with microwaves and smallest for those cooked by the slow method. For each bacterial strain and the total count, the destructive effect of cooking method was not different at the 0.05 level of significance.