Growth Kinetics of Bacillus cereus Vegetative Cells and Spores in Glutinous Rice Dough at Various Environmental...

The growth and proliferation of Bacillus cereus in the processing environment are important reasons why the cell number in the final glutinous rice product exceeds the risk threshold. This study investigated the growth kinetics of B. cereus vegetable cells and their spores in glutinous rice dough at constant temperatures ranging from 11°C to 37°C. The results indicated that the Baranyi, modified Gompertz, and Huang models all successfully described the growth curves of the B. cereus vegetative cells and spores in glutinous rice dough, whereas the modified Gompertz model showed the best fitting accuracy in the majority of cases. The secondary Huang square root model successfully described the effects of temperature on the growth parameters of B. cereus vegetative cells and spores. This study revealed that, compared with spores, vegetative B. cereus cells had faster growth rates, shorter lag times, and higher concentrations (≥ 0.7 log CFU/g) than spores did. However, as the environmental temperature increased, the difference in the growth kinetics between the vegetative cells and spores gradually decreased, indicating that the residual spores in food at relatively high temperatures also have a considerable effect on food safety. Finally, an exponential model was regressed to fit the time required for B. cereus in glutinous rice dough to reach the critical threshold of food safety risk of 5 log CFU/g. The modeling of B. cereus growth in glutinous rice dough provides a theoretical basis for optimizing processing procedures to prevent exceeding the threshold before quick freezing of glutinous rice foods.