Studies on the heat resistance of Bacillus cereus spores and growth of the organism in boiled rice.

A comparison was made of the heat resistance of Bacillus cereus spores at 95 degrees C. Spores of serotype 1 strains were more resistant than those of the other types tested. However, there was little difference in the growth rate of the various serotypes in boiled rice at 22 degrees C. Most samples of uncooked rice contained multiple serotypes of B. cereus. These results indicate that the cooking procedure used for the preparation of cooked rice is likely to be selective for certain serotypes, and this is the most likely reason why type 1 is the most common serotype implicated in outbreaks of food poisoning and can be isolated from many routine samples of cooked rice.