Optimization Of Sterilization Parameters In High Voltage Pulsed Electric Field And Research Of Electroporation Mechanism

Food sterilization is an important technical means to guarantee food safety,so the research of food sterilization technology is very important.Traditional heat sterilization technology is mainly through direct or indirect heating food to destruct the protein and enzymes and other life substances in the microorganisms.However,some defects like uncomplete sterilization,the destruction of the physical and chemical structure of the food exists in traditional heat sterilization technique,so it is urgented to research and develope the non-heat sterilization technology.High voltage pulsed electric field(PEF)is a new non-heat sterilization technology,which is of great significance to food safety.The main principle of this technology is to exert high voltage between the two plates to treat the material in the form of a pulsed electric field in order to destroy the membrane of the microorganism and cause perforation and disintegration finally inactivated the microorganism.The technology can sterilized at room temperature,and has some advantages like keep nutritional flavor,safe and efficient,energy saving and environmental protection.With the further research on the high-voltage pulsed electric field,it has been found that it has applications in other fields besides sterilization,including inactivation,denaturation and extraction.Therefore,it is of great value and economic significance to further explore the application of high-voltage pulsed electric field besides lethal microorganisms.In order to further optimize the sterilization effect of microorganisms treated by high-voltage pulsed electric field,the paper explores the optimal parameters for the sterilization of Escherichia coli and yeast with different parameters of PEF.In order to further explore the application of high-voltage pulsed electric field besides lethal microorganisms,the paper explores the effects of microbial sterilization and enzyme activity with high-voltage pulsed electric field treatment.Studying the sterilization mechanism of sterilization after high-voltage pulsed electric field treated is helpful to provide guidance for the effect of sterilization.Therefore,the lethal mechanism of PEF-treated microorganism is further studied,and the influence of different pulse parameters on the electroporation of microbial cell membrane is discussed,which is the industrialization of high-voltage pulsed electric field Achieve theoretical support.The main work:1.First of all,based on the different types of parameters that affect the sterilization effect of high-voltage pulsed electric field,this article aims to find the best combination of sterilization parameters.The results showed that the intensity of high-voltage pulsed electric field and the treat time on the material were the main parameters affecting the results of microbial sterilization.Escherichia coli and yeast were used as the test objects.With the increase of electric field intensity and treat time,the survival rate of the two microorganisms decreased;The change of pulse width in the range of 1 ~ 10μs and the change of pulse frequency in the range of 10 ~ 100 Hz have little effect on the sterilization effect.Yeast cells were found to be more susceptible to PEF treatation in the two selected microbial species.2.Secondly,the dual effects of yeast cell lethality and enzyme activity after high-voltage pulsed electric field treated was explored.The results showed that low-level PEF could enhance non-specific lactonase activity in yeast cells with low yeast mortality.High-intensity PEF could inactivate Saccharomyces cerevisiae.The experimental results can provide technical support and theoretical guidance for the industrialization of yeast cells after high-voltage pulsed electric field treatment.3.Finally,the effect of PEF-treated yeast cell membrane electroporation was studied by nanoscale fluorescent microspheres with different particle sizes.The results showed that PEF treatment resulted in perforation in the yeast cell membrane,and the pore size was related to the electric field intensity and pulse processing time.The electric field strength and pulse processing time are positively correlated with the cell membrane electroporation pore size.