Kinetics of Microbial Inactivation for Alternative Food Processing Technologies High Voltage Arc Discharge

High voltage arc discharge is a method to pasteurize liquid foods by applying rapid discharge voltages through an electrode gap below the surface of aqueous suspensions of microorganisms. Inactivation of microorganisms and enzymes contained in food products by electrical discharges began in the 1920s with the electropure process for milk. This process consisted of passing an electrical current through carbon electrodes and heating milk to 70 ° C to inactivate Mycobacterium tuberculosis and Escherichia coli (BarbosaCánovas and others 1999). It was one of the first electrical techniques used by the food industry to pasteurize milk (Palaniappan and others 1990). When rapid high voltages are discharged through liquids, a multitude of physical effects (intense waves) and chemical compounds (electrolysis) are generated, referred to as electrohydraulic shock, which inactivate the microorganisms (Edebo and Selin 1968). Enzymes are also inactivated by high voltage arc discharges. Inactivation is attributed to oxidation reactions mediated by free radicals and atomic oxygen. There is no significant temperature increase during treatment by arc discharge. The major drawbacks of this electrical method, however, are contamination of the treated food by chemical products of electrolysis and disintegration of food particles by shock waves (Barbosa-Cánovas and others 1999). The method based on continuous high voltage arc discharges was not considered suitable for use in the food industry (Dunn and Pearlman 1987; Jayaram and others 1991). More recent designs show some potential; however, chemical reaction products need to be identified and results validated.