Abstract:
Bacillus cereus is one of the major causes of food poisoning bacteria involved in rice
and rice-based foods. It causes vomiting-type of food poisoning when more than 10
5
CFU/g presented in food. Three food-grade sanitizers were studied for their
effectiveness to reduce B. cereus and total mesophilic bacteria without affecting
sensory acceptance of sanitized cooked rice at the same time. The sanitizers used in
the study were chlorine, citric acid and chlorine dioxide.. The effective concentration
of chlorine, citric acid and chlorine dioxide in reducing Bacillus cereus and total
mesophilic bacteria were 250 ppm, 0.5% and 1.0 mg/L, respectively. Inoculation of
pathogenic B. cereus UBCC026 strain isolated from contaminated food into cooked
rice was done to determine the effect of sanitizers on reducing total mesophilic
bacteria and B. cereus. Treatment of 0.5% citric acid and 1.0 mg/L chlorine dioxide
were suitable for rice sanitization because these treatments did not cause any changes
of sensory characteristic of cooked rice. However, chlorine at concentration of 250
ppm was not a suitable sanitizer for rice since it showed significant (p < 0.05)
differences in sensory attributes from control. Chlorine dioxide at concentration of
1.0 mg/L reduced at least 2.34 log10 CFU/g of total mesophilic bacteria and 2.64 log10
CFU/g of B. cereus. It was found that the most suitable sanitizer for rice sanitization
was 1. 0 mg/L chlorine dioxide because it is the most effective in reducing total
mesophilic bacteria and B. cereus compared to other two sanitizers without affecting
sensory acceptance of the cooked rice.
