Growth and survival of Bacillus cereus from spores in cooked rice – One-step dynamic analysis and predictive modeling

Abstract

Bacillus cereus is a spore-forming foodborne pathogen that can produce toxins causing emetic or diarrheal intoxication. Food poisoning caused by B. cereus is a significant public health concern as it is frequently associated with the consumption of starch-based food products, which are a staple food worldwide. The objective of this study was to investigate the growth and survival of B. cereus in cooked rice under changing temperatures between 1 and 48 °C. A one-step dynamic analysis was used to directly construct a tertiary model to describe the growth and survival of B. cereus and estimate the kinetic parameters.The results of one-step dynamic analysis showed that the minimum, optimum, and maximum growth temperatures were 8.2, 37.6, and 46.8 °C, respectively, with an optimal specific growth rate of 2.21 ln CFU/g/h or 0.96 log CFU/g/h. These parameters agreed well with the reported typical growth kinetics of this microorganism. In addition, this study found that the populations of B. cereus decreased gradually at the rate of 1.21 × 10−3 ln CFU/g/h per °C or 1.2 × 10−3 log CFU/g/h per °C below the minimum growth temperature.The tertiary model was validated using three dynamic growth and survival curves. The results showed that the root-mean-square-error of the predictions was 0.5 log CFU/g, suggesting that the model is reasonably accurate in predicting the growth of B. cereus in cooked rice. The results of this study can be used to predict the growth and survival of B. cereus and assess its risk in cooked rice or other starch-based products exposed to a relatively wide temperature range during manufacturing and distribution.