Abstract:The investigation of the pathogenic microbial contamination of strawberry revealed that Bacillus cereus had a high detection rate. To study the changes in the number of Bacillus cereus on the surface of strawberry at different temperatures and packaged using different methods, the growth of Bacillus cereus on the surface of the strawberries packaged in a crisper or wrapped with plastic wrap was measured at 7 ℃, 15 ℃, 25 ℃ and 30 ℃. The Baranyi Roberts model was used as the primary model to fit the growth curve of the Bacillus cereus in strawberries at different temperatures and with different packaging methods, followed by model verification. The results showed that the growth of the Bacillus cereus refrigerated at 7 ℃ was slow and independent on the packaging method. During the low temperature storage at 15 ℃, the lag periods for both packaging methods were essentially the same, but the growth decreased by 0.7 lg cfu/g in the case of membrane package compared with the case of using crispers, suggesting that the plastic wrap might exert a certain degree of antibacterial effect at this temperature. During the storage at 25 ℃ and 30 ℃, the specific growth rate and lag period were essentially the same for the two packaging methods, with an increase of 2.9 and 3.2 lg cfu/g, respectively, in the growth of Bacillus cereus after 42 h, indicating that storage temperature was the main factor affecting Bacillus cereus. Therefore, Bacillus cereus will bring potential safety risk of strawberry consumption under high temperature conditions. The results of this study provide important information for quantitative microbial risk assessment.
