Electrical environment surrounding microbes exposed to pulsed electric fields

Inactivation of microbes by the application of intense pulsed electric fields (/spl sime/10 to 40 kV/cm) could result in low-temperature pasteurization of liquid foods. Advantages over conventional heat pasteurization include longer shelf-life, better flavor, and less enzyme damage. Numerical modeling of electrical parameters near the microbe during exposure to these intense electric fields is described. The continuity equation describes movement of positive and negative ions while Gauss's law yields the electric field after movement of the ions. One negative ionic species and one positive ionic species are assumed to be in the suspension fluid and protoplasm of the microbe. The microbe membrane is modeled as a nonconducting dielectric. With application of unidirectional electric fields, free volume and free surface charge densities form along the membrane. Comparison is made with a uniform conductivity model and it is shown that significant differences exist in parameters such as ion concentration, free surface charge density, free volume charge density, heat sources due to conduction current, and ionic injection at membrane surfaces.