Space charge near microbes during pulsed electric field pasteurization of liquid foods

Inactivation of microbes by the application of pulsed electric fields could result in low temperature pasteurization of liquid foods. Advantages over conventional heat pasteurization include longer shelf life, better flavor, and less enzyme damage. In this work, fields as high as 40 kV/cm have been applied to milk, apple juice and an electrolyte that was inoculated with microorganisms. Modeling of the microbes during exposure to these intense electric fields is described. Suspension solution and liquid protoplasm are modeled with a relative permittivity of 81 and each contains two species of ionic charge carriers (one species plus and one species minus). The microbe membrane is modeled with a relative permittivity of 2 and zero conductivity, The continuity equation has been solved numerically in 1 dimension for low ion concentration in order to investigate the transient behavior of space charge sheaths near the microbes. The free surface charge density, which accumulates on both sides of the cell membrane is also described by this model. Mesh size and simulation time step were adjusted to resolve space charge sheath dynamics near the microbes