乙型副伤寒沙门氏菌在鲜切黄瓜中的生长行为及预测模型建立

为建立不同温度条件下鲜切黄瓜中乙型副伤寒沙门氏菌的生长预测模型,将新鲜黄瓜切丁,添加乙型副伤寒沙门氏菌,分别在10、15、20、25、30和35℃下的恒温条件下贮藏,以观察细菌的生长。使用USDA综合病原体建模程序(USDA-IPMP)拟合每个温度下每种细菌的生长曲线,以找出描述该细菌生长的最适初级生长模型,并拟合得到最大比生长速率。通过温度对初级模型中最大比生长速率的生长动力学拟合,分别建立Ratkowsky、Huang rate、Cardinal、Arrhenius-type二级生长模型,并进行数学评估和实测样品验证。结果表明,实验数据和生长曲线显示乙型副伤寒沙门氏菌的生长表现出三个阶段,包括延滞期,指数期和稳定期。乙型副伤寒沙门氏菌的延滞期时间随着孵育时间的增加而降低。相反,乙型副伤寒沙门氏菌的生长速率随着孵育温度而增加,由此表明风险随温度的升高而增加。使用Baranyi和Huang初级模型分析两种病原体的生长曲线,使用Ratkowsky、Huang平方根模型、Cardinal和Arrhenius模型描述温度对贮藏时间细菌生长的影响,同时应用实验数据和样品实测验证评估所建立的预测模型。从该研究中获得的结果和预测模型可用于预测鲜切黄瓜产品中乙型副伤寒沙门氏菌的生长。

Mathematical modeling of growth of Salmonella paratyphi B and Staphylococcus aureus in ready-to-eat cucumber slices

Fresh-cut cucumber slices which were inoculated with Salmonella paratyphi B were incubated under constant temperature conditions between 10, 15, 20, 25, 30 and 35℃ to observe the growth of bacteria. The growth curves of each bacterium under each temperature were analyzed using the USDA Integrated Pathogen Modeling Program(USDA-IPMP)to find the most suitable primary models for describing the bacterial growth. The effect of temperature on bacterial growth rate and lag time was also evaluated using various secondary models. Experimental data and growth curves showed that the growth of Salmonella paratyphi B exhibited three phases, including lag, exponential, and stationary phases. The lag time of each bacterium decreased as the incubation time increased. In contrast, the growth rate of both bacteria increased with the incubation temperature, suggesting increased risks at elevated temperatures during temperature abuse. The growth curves of both pathogens were analyzed with the Baranyi and Huang primary models, while the Ratkowsky and Huang square-root models, Cardinal and the Arrhenius-type model were used to describe the effect of temperature on bacterial growth during storage. The predictive models were validated using experimental data. The results and predictive models obtained from this study can be used to predict the growth of Salmonella paratyphi B in fresh-cut RTE cucumber products.