ABSTRACT
Application of pulsed electric “eld (PEF) technology is based on the fact that many foods can conduct electricity when they are placed between the electrodes of an electrical circuit because of the presence of ions (Zhang et al., 1994a,c). Foods are subjected to different electrochemical reactions or changes under the applied electric current, and these reactions can cause microbial inactivation. Because of the electrical resistance of the foods, several reactions such as ohmic heating, electrolysis, cell membrane disruption, and shock waves caused by arc discharge can occur (Hulsheger and Niemann, 1980; Sitzmann, 1995; Sastry and Barach, 2001; Zuckermann et al., 2002). Ohmic heating is formed by the conversation of applied electrical energy to the heat instantly inside the food, and the amount of the heat is directly related to the current induced by the voltage gradient in the “eld and the electrical conductivity (Sastry and Li, 1996). It should be noted that these reactions are not independent from each other, and the application of electrical energy determines the individual effect on microorganisms. In order to minimize the undesirable effect of each reaction such as temperature increase, electrolytic oxidative effects, and disintegration of food particles, which have adverse effect on foods, duration of the high-voltage pulses were applied with relatively long intervals (Hulsheger and Niemann, 1980; Palaniappan and Sastry, 1990; Zhang et al., 1994a; Sitzmann 1995), pulses applied during process is practiced with extremely short duration (1-100 μs), and pulse intervals between discharges is adjusted from 1 ms to several seconds (Qin et al., 1995b). On the other hand, applied electric “eld is kept between 10 and 80 kV/cm in order to obtain maxiumum amount of microbial and enzyme inactivation (Barbosa-Canovas et al., 1999).
