ABSTRACT
The dehydration process is used to preserve the perishable foods by removing the moisture content and thereby increasing the shelf-life of the product. Refractance window (RW) drying is a novel pre-eminent dehydration technology which dehydrates the wet food products onto the thin Mylar film, which is transparent to infrared (IR) radiation and creates as a ‘window’ for drying. It enhances the self-limiting drying process in which the hot water transmits the heat energy into the wet product by forcing the product moisture to evaporate. Heating water transmits heat energy within itself by conduction, convection, and radiation. Among them, radiation is the most rapid process. In RW dryer, the circulating water temperature is maintained between 95 and 98°C. During drying, the hot water surface is covered by a Mylar film which blocks the evaporation of water and its heat loss. Hence, the product temperature remains at 60-72°C. At this reduced temperature, the pharmaceutical and bioactive products can be dried efficiently. This ideal technique promises to heat-sensitive food products by processing at low temperature and rapid drying with high retention of sensory, nutrients, and bioactive compounds in the end product. By applying this technique, dried products with free-flow in nature, lower water activity, and good storage stability can be achieved.
