One-step dynamic analysis of growth kinetics of Bacillus cereus from spores in simulated fried rice – Model development, validation, and Marko Chain Monte Carlo simulation

Abstract

Bacillus cereus is a spore-forming pathogen capable of producing an emetic toxin and several diarrheal enterotoxins that may cause outbreaks of foodborne illness often associated with rice-based and other farinaceous foods. Therefore, the objective of this study was to investigate the growth kinetics of B. cereus from spores in simulated egg fried rice.The growth of B. cereus was observed under dynamic conditions. Three independent growth curves were analyzed simultaneously using a one-step dynamic analysis (OSDA) to determine the kinetic parameters. The results showed that the minimum, optimum, and maximum growth temperatures were 11.8, 40.8, and 50.6 °C, respectively, with an optimum specific growth rate of 2.4 per h. The root-mean-square-error (RMSE) of model development was 0.4 log CFU/g. Deterministic validation with another 3 independent dynamic temperature profiles showed a RMSE of 0.5 log CFU/g. With Markov Chain Monte Carlo simulation, the RMSE of prediction was only 0.3 log CFU/g.This study proved that OSDA is an effective and efficient method for quickly developing integrated predictive models and estimating kinetic parameters. The resulting integrated model can be used to accurately predict the growth of B. cereus and for managing its risks associated with egg fried rice. The developed kinetic models also can be used to guide restaurant owners and catering establishments to properly prepare and store egg fried rice and other related products to prevent the growth of B. cereus. According to the model, the growth of mesophilic B. cereus is unlikely to occur if the food is stored below 10 °C.