Abstract
The risk of food poisoning and growth of spoilage bacteria in Awa-Uirou, a sticky rice cake containing sweet red bean paste, was evaluated. Toxin-producing bacteria such as Staphylococcus aureus and Bacillus cereus are the main causes of food poisoning linked to this kind of food. The water activity in this product is in the range suitable for growth of S. aureus, B. cereus, and B. subtilis. The viable count of S. aureus or B. cereus spore cocktail was significantly reduced to 2.3 log colony-forming units (CFU)/g after 70 minutes steaming treatment at 100°C. However, the heat-resistant endospores of B. subtilis germinated during storage at 30°C to cause appreciable syneresis of the starch gel matrix in 4 days. The addition of 0.5% glycine before steaming treatment was found to effectively suppress the growth of B. cereus but was not effective in controlling S. aureus throughout the 7 days incubation period at 30°C. On the other hand, S. aureus and B. cereus could grow > 5.0 log CFU/g in an inoculated sample without glycine within 3 days when stored at 30°C. Moreover, addition of 0.5% glycine before the steaming process did not have any significant effect on color, texture, or taste of sticky rice cake. Therefore, results of this study demonstrated that the addition of 0.5% glycine before the steaming process could inhibit B. cereus and B. subtilis multiplication in the steamed rice confection which in turn may help reduce the risk of food poisoning or quality loss.