脉冲电场灭菌条件的优化

Optimization Study on Pulsed Electric Field on E.coli by Response Surface Methodology

研究了脉冲电场连续处理设备对E．coli ATCC25922的灭菌效果。结果表明，随着电场强度（5～30kV／cm）和时间（133～266ms）的增大，大肠杆菌灭菌效果提高，最高可获得7．9个活菌对数的减少。使用Design Expert7．0软件对PEF灭菌效果进行了设计并进行实验分析，发现电场强度与时间对大肠杆菌的灭菌效果的影响都极其显著（P〈0．01），并且电场强度比时间更能显著影响灭菌效果。根据响应面结果对灭菌条件进行优化，得出大肠杆菌的最优灭菌条件为：电场强度35．6kV／cm，处理时间为256．1ms，该灭菌条件下可灭活8．3个活菌对数。

E. coli ATCC25922 was treated by a laboratory scale continuous PEF system. Results showed that increase in inactivation ratio with the increase of applied electric field strength （5 - 30 kV/cm ） and treatment time （133 -266ms ） and ultimately a stable value, which can result in 7.9 log cycle E. coli lethal rate. Single factor tests and Response Surface Method （RSM） analysis results demonstrated that factors of both electric field strength and treatment time affect E. coli lethal rate significantly（P 〈0.01 ）, and electric filed strength has a more significant impact on sterilization effect. Accordingly, the optimum inactivation conditions acquired was electric field strength 35.6kV/cm and treatment time 256.1 ms, which result in 8.3 log cycle E. coli lethal rate.