Development in the Combined Treatment of Coating and Osmotic Dehydration of Food - A Review

Abstract

Osmotic dehydration is gaining considerable attention as a minimal processing method because of its advantages such as saving energy to compliment drying process, better control of flavor loss and tissue damage problems and improved retention of color and nutritional constituents. The problems of flavor loss, tissue damage, color degradation and nutritional loss are present in traditional hot air drying due to the high temperature involved. However, except for candied food, large penetration of solute into the food becomes a major problem in osmotic dehydration. The application of a coating on food prior to osmotic dehydration is a promising solution to alleviate the large solute intake problem. Edible coatings serve as a barrier to limit the penetration of solute without having an adverse effect on water removal. This paper focuses on this combined technology and its potentials. The effects of edible coatings on both water and solute mass transfer in osmotic dehydration are reviewed. Suitable coating materials and their applicable concentration range for osmotic dehydration of food are evaluated. Mathematical models describing the mass transfer in osmotically dehydrated food with coatings are also reviewed.