Osmotic Dehydration of Fruits and Vegetables

Abstract

The flux of water is much larger than the counter-current flux of osmoactive substance. For this reason the process is called osmotic dehydration or osmotic dewatering. Osmotic dehydration is a complex process of countercurrent mass transfer between the plant tissue and hypertonic solution. Fruits and vegetables undergoing processing come from different parts of a plant. Sucrose, lactose, glucose, fructose, maltodextrins, and starch or corn syrups are commonly used in osmotic dehydration of fruits and vegetables. Solutions of sugars are mostly used to dehydrate fruits and glycerol, starch syrup, and sodium chloride are used for vegetables. Osmosed fruits and vegetables have different forms that come from the technology and consumer requirements. Use of osmotic dehydration practically eliminates the need to use preservatives such as sulfur dioxide in fruits. Fruits and vegetables treated by osmosis can be further dehydrated in a convection dryer to lower the water activity to the level of 0.65–0.90.