Refractance Window Drying: Technology and Product Quality Characteristics

Abstract

Refractance Window drying (RWD) is an innovative and energy-efficient dehydration technology that preserves the quality and nutritional integrity of food products. Utilizing conduction, convection, and radiation, it operates at relatively low temperatures (39–70°C), making it ideal for heat-sensitive materials. The process involves heat transfer through an infrared-transparent membrane in contact with heated water, enabling rapid moisture removal while minimizing the degradation of ascorbic acid, carotenoids, and phenolics. Compared to conventional drying methods, RWD offers superior energy efficiency, lower operational costs, and enhanced retention of sensory and functional properties. Dried products exhibit vibrant colours, high rehydration ratios, and minimal textural changes, comparable to freeze-dried products but with significantly lower energy demands. This manuscript aims to provide a comprehensive review of RWD technology, focusing on its working principles, key process parameters, and impact on product quality. Additionally, it highlights recent advancements such as hybrid IR-assisted RWD and discusses its potential applications in the food industry. The novelty of this study lies in its detailed assessment of RWD’s role as a sustainable alternative to conventional drying methods, emphasizing its ability to enhance energy efficiency and product integrity while addressing challenges related to scalability.