菌液浓度对大肠杆菌超高压杀灭效果的影响

本实验采用响应曲面法的中心组合设计法,对大肠杆菌超高压杀灭效果进行了研究,着重探讨了菌液浓度对致死率的影响。依据实验结果,建立了大肠杆菌超高压致死的响应模型,y=81.26-8.3x1+29.3x2+5.5x3+7.7x4+11.2x1x2-1.4x1x3+3.4x1x4-5.4x2x3-4.8x2x4-1.4x3x4+0.5x12-1.9x22+1.1x32-6.7x42,方差分析表明,模型拟合度高,实验误差小,可应用于压力对大肠杆菌致死效应的分析和预测。样品的菌液浓度是超高压杀菌效果的显著影响因素,并与压力因素之间存在显著的交互作用。大肠杆菌的致死率随着菌液浓度的增加而下降,随着压力的增加而迅速上升,低含菌量时,较低的压力就可达到杀菌要求,而高含菌量则需较高的压力。此外,压力、温度、时间均是超高压杀菌效果的显著影响因素。根据加工对象含菌量的不同,应选择合适的工艺参数,使超高压杀菌操作更有效和具有实际意义。

Effects of Bacteria Concentration on Sterilization of Escherichia coli in High Pressure Process

In this experiment, effects of high pressure on Escherichia coli were studied and effects of bacteria concentration on lethal rate was highlighted by applying central composite design of response surface methodology.Based on the results,the model is established as y=81.26-8.3x1 + 29.3x2 + 5.5x3 + 7.7x4 + 11.2x1x2-1.4x1x3 + 3.4x1x4-5.4x2x3-4.8x2x4-1.4x3x4 + 0.5x12 -1.9x22 + 1.1x32-6.7x42. Analysis of variance showed that the model is feasible, so it could be used to analyse and predict the experiment. Bacteria concentration of sample is a significant factor in treatment and there is a significant interaction between bacteria concentration and pressure. Results showed that lethal rate decreases with bacteria concentration going up and increase with pressure going up. For example, to low bacteria concentration sample,low pressure could sterilize,while high bacteria concentration sample need high pressure to sterilize.Pressure,temperature and time are also significant factors for high pressure process.It is sugguested that proper parameters should be chosen according to bacteria concentrations in different samples so as to make high pressure sterilization more efficient and practical.