含果粒液体食品微波杀菌动力学模型的比较研究

Comparison and analyses of inactivation kinetics models for microwave inactivation of two foodborne pathogens in liquid food containing fruit particles

摘要:

为了描述微波处理下微生物致死动力学的变化规律，以含柑橘果粒的含糖液体作为对象，并分别接种了单增李斯特菌和大肠杆菌，选用800 W微波功率对样品进行杀菌处理，考察其杀菌效果。分别应用一级动力学模型、Weibull模型、Log-Logistics模型和Dose-Response模型对微波处理条件下两种微生物的失活曲线进行动力学分析。结果表明：微波加热40 s过程中，大肠杆菌和单增李斯特菌的活菌数迅速下降，分别下降了2.5和3.5个对数值数量级，两者的热敏感性不同，杀菌过程中致死速率存在差异，两者失活曲线形状较为相似，加热初始活菌数下降缓慢，当温度达到60 ℃时迅速下降，当温度超过100 ℃时，致死速率逐渐趋缓。一级动力学模型不能用于描述微波杀菌下两种微生物致死规律。Weibull模型、Log-Logistics模型和Dose-Response模型均能较好的拟合微波处理下两种微生物的失活曲线，用五个模型评价参数精确因子、偏差因子、根平均方差、根平方和以及决定系数综合分析比较了不同数学模型的拟合程度，Dose-Response模型能最好的拟合单增李斯特菌的失活曲线，Log-Logistic模型能最好地拟合微波杀菌条件下大肠杆菌的失活曲线。

Abstract:

In order to describe microbial death kinetics under microwave treatment, the sugar solution with orange particles was used as the research material. As the sample, Escherichia coli and Listeria monocytogenes were suspended in sugar solution with orange particles. Two samples were exposed to microwave at 800W for 40 s, the bactericidal effect was evaluated. Linear, Weibull, log-logistic and Dose-Response functions were used to model survival curves of two pathogens in sample. The results showed that a treatment of 800W for 40s reduced the counts of Escherichia coli by 2.5 log10 and Listeria monocytogenes by 3.5 log10. Since the thermal sensitivity of two foodborne pathogens is different, the death rates of two foodborne pathogens were different in sterilization process. Both the survival curves showed a slow initial drop in bacterial counts followed by rapid drop when the treatment temperature to 60 ℃, the last tailing tail was caused by a diminishing inactivation rate. First order kinetic model can not be used to describe the law of microbial death under microwave sterilization. Weibull model, Log-Logistics Model and Dose-Response model all can better fit the inactivation of microorganisms. However, five model parameters were used for evaluating the stand or fall of model, the comparison of these indices indicates that Dose-Response model consistently produced better fits to inactivation data of Listeria monocytogenes than others. And Log-Logistic model had better fitting degree for Escherichia coli than others.