Pulsed Electric Fields for Pasteurization: Food Safety and Shelf Life

Abstract

Pulsed electric field (PEF) processing is a non-thermal method of food preservation that uses short bursts of electricity to inactivate microbial populations in foods and causes minimal or no detrimental effect on food quality attributes since it preserves foods using minimal heat or without heat. PEF processing involves treating foods placed between electrodes by high voltage pulses in the order of 20–80 kV for microseconds. The applied high electric field results in microbial inactivation. PEF treatment has lethal effects on various species of vegetative bacteria, molds, and yeasts. A series of short, high-voltage pulses breaks the cell membranes of vegetative microorganisms in liquid media, allowing for the formation of new pores and/or the expansion of existing pores (electroporation) in microbial cell membranes. Pore formation is reversible or irreversible depending on factors such as the electric field intensity, the pulse duration, and number of pulses. As a result of pore formation, the membranes of PEF-treated cells become permeable to small molecules; permeation causes swelling and eventual rupture of the cell membrane. A typical continuous PEF processing system for food pasteurization is composed of four major components: pulse generator, PEF treatment chamber, fluid handling system, and control and monitoring devices. There are multiple processing conditions associated with each of these components to be selected or controlled to achieve a desirable reduction in microbial populations. Application of PEF technology has been successfully demonstrated for the pasteurization of foods such as juices, milk, yogurt, soups, and liquid eggs. This chapter introduces various PEF systems, processing parameters, and theory of microbial inactivation; discusses PEF applications for food safety and shelf life; and concludes with main challenges and future trends.