电场强度对微波场非热效应杀菌效果及机制的影响研究

Study on the influence of electric field strength on the inactivation effect and mechanism of non-thermal effect of microwave field

目的研究在相同辐照时间和样品终温下,不同电场强度对微波场非热效应灭活生孢梭菌的效果及机制的影响。方法利用同步升温法将微波场的热与非热效应区分开来,以获得非热效应对微生物的影响。基于微波加热腔内电场强度呈中间高两边低的分布,将初温不同的两组样品置于加热腔内不同位置(1号和2号位)以分析不同的电场强度对微波场非热效应的影响。经相同处理时间后样品终温基本一致(排除温度对非热效应的影响),进而分析电场强度对非热效应的杀菌效果及机制的影响。通过平板计数法、紫外分光光度计和激光共聚焦扫描显微镜分析不同电场强度对非热效应带来的杀菌效果、胞内大分子的泄漏量以及细胞膜通透性变化的影响。结果初温为10℃和30℃的样品分别在电场强度较大的1号位和电场强度较小的2号位经微波辐照1.5 min后,两样品终温无显著差异(P>0.05)。微波场非热效应导致的1号位微生物降低的数量级、胞内大分子的泄漏量以及细胞膜通透性的改变均显著高于2号位(P<0.05)。结论相同的辐照时间下,随电场强度的增大微波非热效应对细胞膜通透性的破坏作用也随之增强,造成更多的胞内物质泄露,最终导致更多的微生物灭活。因此,电场强度的增加可以带来更多的非热效应及其对微生物的致死效果。

Objective To investigate the impact of different electric field strengths on the effectiveness and mechanism of non-thermal inactivation of Clostridium sporogenes by microwave field at the same exposure time and final sample temperature.Methods The thermal and non-thermal effects of the microwave field were distinguished using the same time-temperature profile method to determine the effect of non-thermal effects on microorganisms.Based on the microwave heating cavity,the electric field strength was high in the center and low on either side of the distribution,two groups of samples with different initial temperatures were placed in different positions(No.1 and No.2 positions)in the heating cavity to analyze the influence of different electric field strengths on the non-thermal effect of the microwave field.After the same processing time,the final temperature of the samples was basically the same(excluding the effect of temperature on the non-thermal effect),and then analyzed the electric field strength on the non-thermal effect of sterilization effect and the mechanism of impact.The impact of different electric fields on the bactericidal effect of non-thermal effects,macromolecule leakage,and membrane permeability changes were analyzed using plate counting,ultraviolet spectrophotometry,and confocal laser scanning microscopy.Results After irradiating the samples with initial temperatures of 10℃and 30℃for 1.5 min using microwaves at positions 1 and 2,respectively,where the electric field intensity was higher and lower,respectively,there was no significant difference in the final temperatures of the two samples(P>0.05).The study found that the non-thermal effects of the microwave field resulted in a significantly higher order of magnitude of microbial reduction,leakage of intracellular macromolecules,and alteration of cell membrane permeability in site 1 compared to site 2(P<0.05).Conclusion At the same irradiation time,the impact of microwave non-thermal effects on cell membrane permeability increased with the rising electric field intensity.This resulted in more intracellular material leakage and ultimately led to greater microbial inactivation.Therefore,increasing the intensity of the electric field can result in more non-thermal effects and increase its lethal impact on microorganisms.