Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2008
Publication Date: 5/1/2008
Citation: Okahisa, N., Inatsu, Y., Juneja, V.K., Kawamoto, S. 2008. Evaluation and control of the risk of food borne pathogens and spoilage bacteria present in “Awa-Uirou”, a sticky rice cake containing sweet red bean paste. Foodborne Pathogens and Disease. 5(3):351-359.
Interpretive Summary: One of the most common types of food poisoning in Japan is caused by the consumption of steamed sticky rice cake contaminated with Bacillus cereus, a common foodborne pathogen. Illnesses have been traditionally associated with B. cereus spores contaminating this product. Also, the product can also be spoiled due to the growth of B. subtilis, a spoilage bacterium. Accordingly, there is a need to explore the potential use of a preservative in such foods. We determined that the addition of 0.5% glycine before the steaming process could serve as a hurdle to growth of bacteria in steamed rice confection and prevent the risk of food poisoning and quality loss. These findings will be of immediate use to retail food service operations and regulatory agencies to ensure the microbiological safety of sticky rice cake and related foods.
Technical Abstract: The potential for growth of food poisoning or spoilage bacteria in “Awa-Uirou”, a sticky rice cake containing sweet red bean paste was evaluated. The water activity (aw 0.92) was in the range suitable for the growth of Staphylococcus aureus, Bacillus cereus and Bacillus subtilis. The viable cell counts of S. aureus cells or B. cereus spore cocktail were significantly reduced to a non-detectable level (2.3 log CFU/g) after 70 minutes of steaming at 100C. However, the heat resistant spores of B. subtilis grew during subsequent storage at 30C to cause appreciable syneresis of the starch gel matrix in 4 days. The addition of 0.5% glycine before the steaming treatment was found to effectively control the growth of B. cereus without affecting the sensory characteristic of sticky rice cake. Inoculated S. aureus cells or B. cereus spores could grow more than 5 log CFU/g within 3 days when stored at 30C. However, the addition of glycine before the steaming process was found to be effective in controlling B. cereus and B. subtilis but was not effective in controlling S. aureus. The results of this study demonstrated that the addition of 0.5% glycine before the steaming process could reduce the the risk of food poisoning and quality loss of rice cakes.