7 - Enzymatic Inactivation by Pulsed Electric Fields

Abstract

This chapter reviews the current information available on the effect of pulsed electric field (PEF) on enzymes, including what is known on the inactivation mechanisms, the factors that influence the changes of activity, as well as the models that are currently used to describe the reduction of enzyme activity. PEF is a nonthermal preservation method that uses high voltage to inactivate enzymes and to produce microbiologically safe foods with fresh-like flavor and taste without significant loss of nutrients. PEF technology is gaining popularity in processing foods as a means to avoid the negative impacts of thermal treatments. PEF treatment involves the application of a short burst of high voltage (kV/cm) to foods placed between two electrodes. To achieve a great extent of enzyme inactivation, higher energy levels than those required to destroy microorganisms are needed. The results of PEF inactivation of enzymes are encouraging in the exploration of an alternative nonthermal method of food preservation. Most enzymes are almost completely inactivated while some show resistance to PEF processing. PEF can be employed as an effective hurdle when used with other preservation factors such as pH and additives, or as a complementary step with mild thermal processes. First-order kinetic models as a function of treatment time or field strength can be successfully used to describe enzyme inactivation.