等离子体活化水对鲜切生菜杀菌效能及贮藏品质影响

Effect of Plasma Activated Water on Microbial Decontamination and Storage Quality of Fresh-cut Lettuce

目的:研究低温等离子体活化水(plasma activated water,PAW)对鲜切生菜的杀菌作用及品质影响。方法:介质阻挡放电低温等离子体设备在电压为35、55和75 kV条件下处理蒸馏水5 min制备PAW。再用PAW清洗生菜5 min,于4℃、85%RH下储藏10 d,每间隔2 d检测样品的微生物(菌落总数、大肠菌群)和生理生化(失重率、颜色、维生素C、叶绿素和多酚氧化酶)等指标。结果:PAW对生菜的杀菌效果随电压的提高而显著提高(P<0.05),贮藏结束时,75 kV处理组的菌落总数和大肠菌群数分别比对照低1.15 lg(CFU/g)和1.38 lg(MPN/100 g)。与对照组相比,不同处理电压的PAW能够有效抑制多酚氧化酶活性,抑制L^*值上升和总色差值下降(P<0.05);35和55 kV处理对样品的维生素C及叶绿素含量无显著影响(P>0.05),但是电压增加到75 kV时会产生不利影响。结论:PAW对鲜切生菜抑菌保鲜的最佳处理电压是55 kV。

Objective:The microbial inactivation and quality changes of fresh cut lettuce treated with cold plasma activated water were investigated in this paper.Methods:PAW was produced by dielectric barrier discharge at 35,55 and 75 kV for 5 min.All samples were washed with PAW for 5 min and stored for 10 days(4℃,85%RH).The microbe(total aerobic plate count and coliform group),as well as the weight loss rate,color,ascorbic acid,chlorophyll and polyphenol oxidase activity of the samples were tested every two days.Results:The sterilization effect of PAW on lettuce significantly increased with the increase of treatment voltage(P<0.05).At the end of storage,the total colony count and coliform count of the 75 kV treatment group were 1.15 lg(CFU/g)and 1.38 lg(MPN/100 g)lower than the control group,respectively.Meanwhile,PAW treatment could effectively decrease the PPO enzyme activity and color change of samples(P<0.05),but there was no significant difference between different treatment groups(P>0.05).The 35 and 55 kV treatments had no significant effect on the ascorbic acid and chlorophyll content of the samples,but when the voltage increased to 75 kV,it would have an adverse effect.Conclusion:The optimum treatment voltage of PAW for keeping fresh of fresh cut lettuce was 55 kV.