Influence of Pulsed Electric Field on Escherichia coli and Saccharomyces cerevisiae

Heat sterilization destroys the color, smell, taste, and nutrients of food. Pulsed electric field can effectively kill microorganisms for many foods at room temperature without compromising sensory and nutritional quality. The effect of pulsed electric field on the sterilization rates of Escherichia coli and Saccharomyces cerevisiae was investigated. The fundamental mechanism of pulsed electric field sterilization on S. cerevisiae was briefly discussed. The inactivation of E. coli and S. cerevisiae increased as the electric field strength and treatment time increased. Pulsed electric field treatments at 35 kV/cm and 90 μs reduced S. cerevisiae and E. coli by 5.30 and 5.15 log numbers, respectively. The inactivation of E. coli and S. cerevisiae was not remarkable at increased conductivity and the same electric field strength. Concaves and holes in S. cerevisiae cell surface, protoplast deletion, overflow of substances from cells, and denatured DNA were observed. These results supported the hypothesis of “membrane perforation” to explain the mechanism underlying pulsed electric field sterilization.