Use of pulsed electric field pre-treatment to improve dehydration characteristics of plant based foods

Conventional dehydration of fruits and vegetables affects their physical and biochemical status leading to shrinkage, change of colour, texture and taste. Alteration of the physical properties of foods with minimal influence on the quality could be a means of reducing drying time, minimising quality degradation and saving energy. Increasing consumer markets for minimally processed fruits and vegetables have prompted researchers to study combined methods as preservation techniques. Pulsed electric field is one of the more promising non-thermal processing method inducing membrane permeabilisation within a very short time (mus to ms range) leaving the product matrix largely unchanged while positively affecting mass transfer in subsequent processing of foods. Rapid and accurate on-line determination of the state of cell membrane systems is important in optimising various processes (i.e. minimizing cell damage in minimal processes, monitoring disruption for mass transfer purposes and inducing biosynthetic stress/ wound reactions/responses). This paper reviews recent work on the use of pulsed electric fields as an upstream process in dehydration and rehydration of plant based foods. An effective and simple method for quantifying extent of membrane permeabilization is also discussed and suggestions for future work are highlighted. (C) 2002 Elsevier Science Ltd. All rights reserved.