电极间隙对脉冲电场处理器杀菌效果的影响

Pulsed electric field(PEF) is a new non-thermal sterilization technology that has high sterilization efficiency and effectively preserves the nutritional components of liquid food, showing application prospects. As one of the key indexes of PEF sterilization processor, electrode gap dominates the distribution of electric field and directly affects the sterilization effect. In order to optimize the optimal gap parameters and explore the sterilization effect, we designed PEF processors with different electrode gaps (3 mm, 5 mm and 7 mm), and investigated the sterilization effect of PEF on two typical bacteria (staphylococcus aureus and escherichia coli) suspension with specified conductivity (equivalent fresh squeezed grapefruit juice conductivity). The study shows that the maximum voltage that can be applied to the 3 mm electrode gap is 18 kV, while 5 mm and 7 mm gaps can reach 30 kV. When the treatment time is 120 s, the sterilization efficiency of all three gaps can reach 99.99%. Therefore, after the performance of the power supply, energy consumption, and processing capacity are taken into consideration, the 3 mm processor is proposed as the preferred option for application. The influence of applied voltage amplitude on the sterilization effect was evaluated, and it was found that the bacteria content decreased with the increase of applied voltage in a “slow-fast-slow” three-stage process. Furthermore, the trend of change in protein content in the supernatant of bacterial suspension was analyzed, which was found to be in good agreement with the trend of sterilization effect change. Therefore, the results fully indicate that the main mechanism of PEF sterilization is the electroporation of bacterial cells.