Potential of Refractance Window Technology for Value Added Processing of Fruits and Vegetables in Developing Countries

摘要

Refractance Window~(R) (RW) drying and evaporation technology is a novel method for conversion of liquid foods into valued-added powders, flakes, or concentrates. In RW drying systems, fresh fruits and vegetables, after pureeing or juicing, dry withina short time and under very hygienic conditions into valued-added powders with excellent color and high retention of vitamins and antioxidants. Both the drying and evaporation systems are simple and relatively inexpensive when compared with freeze-drying or vacuum evaporators that are more economical in large commercial operations. The drying system was designed based on a novel concept where thermal energy is transferred from hot water to a thin film of pureed product deposited on a transparent plastic conveyor belt in contact with the hot water. The evaporator, which works on the same principle, can be a pre-concentration step prior to drying, thereby shortening drying times and improving thermal efficiency. The RW drying and evaporation systems operate at atmospheric pressure and have been used to produce dehydrated foods with very high quality. This paper presents the principle of Refractance Window drying and evaporation and some results to show its potential for processing fruits and vegetablesthat usually go to waste in many developing countries. Besides solving the food loss problem, the value added and extended shelf life products can boost the nutritional status of people in those countries. Investigations are continuing on retention of antioxidants, changes in structure (molecular weight), and shelf stability of fruits and food polysaccharides processed by this technology.