Research On The Key Technologies Of Sterilization With High Pulsed Electric Field System

Pulsed electric fields( PEF)for inactivation of microorganisms is one of the most promising technologies in the field of non-thermal food processing, which can maintain the original nature of the food as long as possible.In the paper,firstly, according to designing theory and achievements at home and abroad of the PEF generator and processing chamber, it proposes there is a problem of the OSU-4Lsystem in the chamber, that the electric field is uneven , which limits the industrialization progress of the sterilization system.According to the existing problem,in terms of chamber's designing requirement and PEF generator's parameters, it develops two different kinds of processing chambers, static plate and dynamic co-axial. Then it analyzes the fluid flow and electric field distribution of the designed processing chamber models by ANSYS software. Finally, with the developed equipment,we do the sterilization experiment on the liquid whole egg,which is inoculated by E. coli.The results and conclusions are as follows:1. With the increase of the electric field strength, PEF sterilization effect of E. coli is becoming more and more obvious. Thus it demonstrates that sterilization rate is proportional to the electric field intensity.2. Doing sterilization experiment on LWE by using static plate chamber, Probably 5.21 log Sterilization is achieved by using PEF-only processing from 20 kV/cm to 40 kV/cm for 400μs when the Pulsed electric field frequency is 10Hz. Predictably, the E. coli sterilization effect of PEF device is obvious. This shows that the designed static chamber is feasible, and it can be used in the related mechanism research, such as Sterilization and inactivating enzyme.3. Doing sterilization experiment on LWE by using co-axial chamber. Probably 4.8 log is achieved by using PEF-only processing at 40 kV/cm for 400μs.Predictably, the E.coli sterilization effect of PEF device is obvious, This shows that the designed co-axial chamber is feasible, and it can be used in the related mechanism research.4. Doing sterilization experiment on LWE with same parameters of PEF treatment at40 kV/cm for 400μs. We get5.21 log cycle reduction of flat plate electrode and 4.8 log cycle reduction of co-axial electrode and 2.1log reduction of co-field electrode .Sterilization Results show: Plate electrode>co-axial electrode>co-field electrode.This paper contributes to put forward the chamber's existing problem of OSU- 4L system,that the electric field is uneven. Then it designs two types of chambers, static plate and co-axial, whose feasibilitiesare verified by doing experiments on LWE with chambers designed. Finally, it compares the sterilization of chambers designed with the chamber of OSU-4L system.The results indicate: bactericidal effect of static plate electrode is the best,co-field is the worst.This topic comes from "Food non-thermal processing and efficient separation technology project" (2006BAD05A02) fund project of State Key Laboratory of Food Science and Technology of Jiangnan University, and the project is National Key Technology R&D Program in the 11th Five year Plan of china.