Study on Bactericidal Effect and Lethal Dynamics of High Pulsed Electric Field on Pectobacterium carotovorum

In order to identify the optimal sterilization parameters for HPEF on Pectobacterium carotovorum (P. carotovorum), and preliminarily explore its potential mechanism, the main factors affecting the sterilization effect were identified by measuring the survival rate of P. carotovorum under different treatment conditions of HPEF. Then, the effects of different electric field strengths and pulse duty cycles on the growth curve, fatty acid content of cell membrane, cell membrane permeability, and nucleic acid and protein leakage of P. carotovorum were studied, as well as the differences in sensitivity of P. carotovorum to HPEF in different growth periods. Finally, the kinetic model between electric field strength, pulse duty cycle and the survival rate of P. carotovorum was established. The results showed that the electric field intensity and pulse duty cycle were the main factors affecting the killing of P. carotovorum by HPEF. When the electric field strength was 28 kV/cm and the pulse duty cycle was 36.5%, the antibacterial effect was the strongest, with a reduction of logarithmic value at 1.60. Under the action of HPEF, the delay period of P. carotovorum was prolonged and its growth was inhibited. At the same time, the structure of cell membrane was damaged, and the permeability was increased, leading to the serious leakage of intracellular nucleic acid and protein. In addition, P. carotovorum in different growth period had different sensitivities to HPEF, and logarithmic growth period was the most sensitive. Finally, the kinetic equation was established between the log reduction value of lnS and the electric field strength and pulse duty cycle (y=−0.1067x+0.1166 and y=−0.0895x+0.3249). The equation was in accordance with the first-order kinetic model and reflected the growth relationship of P. carotovorum after HPEF treatment well, which provided data support for the selection of appropriate treatment conditions. In this study, the optimal parameters of HPEF inhibiting P. carotovorum were determined, which provided theoretical data for further realization of HPEF sterilization in the industrial application of postharvest and fresh-cutting industries.