Abstract
The effect of heat treatments on food products related to soybean curd contaminated with Bacillus cereus spores was investigated for the purpose of preventing food-poisoning outbreaks by B. cereus. In the case of B. cereus strains isolated from foods, heating foods inoculated with the spores for 20 min at 70°C, 5 min at 75°C, 2 min at 100°C, or 10 sec with a microwave oven plus reheating after standing for 2 hr at 25°C reduced the number of surviving cells within the foods to less than one-hundredth. In the case of a heat-resistant strain isolated from a food poisoning outbreak, heating for 20 min at 70°C plus reheating after standing for 1.5-2 hr at 35°C, heating for 10 min at 75°C plus reheating after standing for 1.5-2 hr at 35°C, or heating for 2 min at 100°C plus reheating after standing for 4 hr at 25°C was effective. There was not much difference between the flavor components in foods with and without heat treatment at 70°C, as analyzed by gas chromatography-mass spectrometry. These results indicate that these heat treatments are available to control B. cereus spores, without affecting the sensory quality of the foods.
