ELECTRICAL ENVIRONMENT SURROUNDING MICROBES EXPOSED TO PULSED ELECTRIC-FIELDS

Inactivation of microbes by the application of intense pulsed electric fields (similar or equal to 10 to 40 kV/cm) could result in low-tempe rature pasteurization of liquid foods. Advantages over conventional he at pasteurization include longer shelf-life, better flavor, and less e nzyme damage, Numerical modeling of electrical parameters near the mic robe during exposure to these intense electric fields is described. Th e continuity equation describes movement of positive and negative ions while Gauss's law yields the electric field after movement of the ion s. One negative ionic species and one positive ionic species are assum ed to be in the suspension fluid and protoplasm of the microbe. The mi crobe membrane is modeled as a nonconducting dielectric. With applicat ion of unidirectional electric fields, free volume and free surface ch arge densities form along the membrane. Comparison is made with a unif orm conductivity model and it is shown that significant differences ex ist in parameters such as ion concentration, free surface charge densi ty, free volume charge density, heat sources due to conduction current , and ionic injection at membrane surfaces.