Liao Hongmei, Zhang Yan, Hu Xiaosong, Liao Xiaojun, Wu Jihong
Research Centre for Fruit and Vegetable Processing Engineering, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
Int J Food Microbiol. 2008 Aug 15;126(1-2):93-7. doi: 10.1016/j.ijfoodmicro.2008.05.008. Epub 2008 May 15.
Inactivation of Escherichia coli in cloudy apple juice by dense phase carbon dioxide (DPCD) was investigated. The pressures were 10, 20 and 30 MPa, the temperatures were 32, 37 and 42 degrees C. The inactivation kinetic behavior of E. coli conformed to a sigmoid curve with a shoulder and a tail, which was closely related with temperature or pressure. With the increase of temperature or pressure, the shoulder became unclear or even disappeared. The experimental data were well fitted to a model proposed by Xiong et al. [Xiong, R., Xie, G., Edmondson, A.E., Sheard, M.A., 1999. A mathematical model for bacterial inactivation. International Journal of Food Microbiology 46, 45-55], the kinetic parameters of t(lag) (the lag time length), f (the initial proportion of less resistant population), k(1) (the inactivation rate constant of less resistant fraction) and k(2) (the inactivation rate constant of resistant fraction), and t(4)(-)(D) (the time required for an 4-log-cycle reduction of bacteria under a given condition) were obtained from this model. The t(lag) declined from 4.032 to 0.890 min and t(4)(-)(D) from 54.955 to 18.840 min, k(1) was 1.74-4.4 times of k(2). Moreover, the model was validated by more experimental data, the accuracy factor (Af), bias factor (Bf), root mean square error (RMSE), sum of squares (SS), and correlation coefficient (R(2)) were used to evaluate this model performance, indicating that the model could provide a good fitting to the experimental data.
研究了密相二氧化碳（DPCD）对混浊苹果汁中大肠杆菌的灭活作用。压力分别为10、20和30兆帕，温度分别为32、37和42摄氏度。大肠杆菌的失活动力学行为符合具有肩部和尾部的S形曲线，这与温度或压力密切相关。随着温度或压力的升高，肩部变得不明显甚至消失。实验数据与熊等人提出的模型[Xiong, R., Xie, G., Edmondson, A.E., Sheard, M.A., 1999. A mathematical model for bacterial inactivation. International Journal of Food Microbiology 46, 45 - 55]拟合良好，从该模型中获得了t(lag)（延迟时间长度）、f（较不耐药群体的初始比例）、k(1)（较不耐药部分的失活速率常数）和k(2)（耐药部分的失活速率常数）以及t(4)(-)(D)（在给定条件下细菌4个对数循环减少所需的时间）的动力学参数。t(lag)从4.032分钟降至0.890分钟，t(4)(-)(D)从54.955分钟降至18.840分钟，k(1)是k(2)的1.74 - 4.4倍。此外，该模型通过更多实验数据进行了验证，使用准确因子（Af）、偏差因子（Bf）、均方根误差（RMSE）、平方和（SS）以及相关系数（R(2)）来评估该模型性能，表明该模型能够很好地拟合实验数据。
