超高压协同温度处理对绿色魏斯氏菌的失活动力学

Inactivation Kinetics of Weissella viridescens under Ultra-High Pressure Thermal Sterilization Treatment

为了建立超高压协同温度处理对绿色魏斯氏菌在低温烟熏火腿中的失活模型,采用40、45、50℃结合200～500 MPa对接种10~8～10~9 CFU/mL绿色魏斯氏菌的烟熏火腿进行5、10、15、20、25、30 min的超高压处理,同时做相同条件的离体实验进行对比。采用薄层平板计数,以时间为横坐标,亡菌数量级为纵坐标作失活曲线,选择一级线性模型和非线性模型(Weibull和Logistic)进行模型的拟合,用模型的评价因子相关系数R^2、准确因子A_f和均方差验证方程的拟合度。结果表明:经热压结合处理后,接种于烟熏火腿中的绿色魏斯氏菌比相同条件下离体状态的绿色魏斯氏菌的失活更缓慢,可能因为火腿基质中存在一些大分子物质(如蛋白质、脂肪等)对菌体的保护作用。Logistic方程最适合描述绿色魏斯氏菌在两种状态下的失活情况,为预测绿色魏斯氏菌在烟熏火腿中的失活提供了理论依据。

This work was undertaken to establish a model describing the inactivation of Weissella viridescens on lowtemperature smoked ham with ultra-high pressure thermal sterilization(HPTS).Weissella viridescens suspended in phosphate buffered saline and smoked ham inoculated with 108–109 CFU/mL of this strain were subjected to moderate heating(40,45 and 50℃)combined with high pressure(200–500 MPa)held for 5,10,15,20,25,30 min.The number of surviving cells was counted by the thin agar layer method.Inactivation curves describing the logarithmic value of the number of inactivated cells as a function of time were fitted with a first-order linear model and the Weibull and Logistic nonlinear models.The goodness of fit of the fitted models was examined by the correlation coefficient(R2),accuracy factor(Af)and mean square error(MSE).It was found that the inactivation of Weissella viridescens in situ was slower than in vitro after HPTS,which was due to the presence of macromolecular substances in the ham matrix including protein and fat,protecting bacteria from damage.Finally,the Logistic equation was the best model to describe bacterial inactivation in vitro and in situ,and could provide the theoretical foundation to predict Weissella viridescens inactivation on smoked hams.