Refractance WindowTM-Drying vs. Other Drying Methods and Effect of Different Process Parameters on Quality of Foods: A Comprehensive Review of Trends and Technological Developments

Abstract Refractance WindowTM-Drying (RWD) is one such novel fourth-generation drying technology which has recently gained huge attention due to its several advantages. It is employed to dry the heat-sensitive products even juices and purees to retain the product color, aroma, antioxidant compounds, and nutritional properties. This technology dries the product through a thin, transparent infrared film which effectively forms a "window” for drying, keeping the product's temperatures very low and ensuring rapid drying, involving all modes of heat transfer. The drying temperature, time, cost, and energy consumption are also lower in this case, but thermal efficiency and product's quality are higher than conventional drying technologies like drum drying, freeze-drying, spray drying, tray drying, etc. which possess their own limitations. The present work, therefore, summarizes the recent trends in RWD, emphasizing its impact on process and food quality properties, and highlights differences between RWD and existing drying technologies. This manuscript discusses in detail the effect of RWD on physical, chromatic, biochemical, functional, structural, textural, and microbial properties of end-product. Further, the patents based on RWD have also been highlighted comprehensively for the first-time, considering their contribution to scientific knowledge and as a platform to support the upcoming developments in the field.