Refractance Window Drying–a Revisit on Energy Consumption and Quality of Dried Bio-origin Products

The postharvest losses of agricultural and horticultural crops are high as a result of the lack of postharvest handling, storage, and processing technologies in India. Over the years, drying has been an essential food preservation strategy for reducing postharvest losses and extending the shelf life of products. Traditional drying techniques exhibit a negative impact on the flavour, colour, nutritional properties, and retention of bioactive components due to the high-temperature exposure. An alternative for traditional drying methods is required to retain quality and maintain greater nutritional content in processed foods. Refractance window drying (RWD) is a thin-film drying technique that uses high heat and mass transfer rates to accelerate the moisture removal process. This technique dries the product spread over a transparent plastic film with creation of a drying “window,” ensuring lower product temperature and rapid drying by using all modes of heat transmission. When compared to traditional drying methods such as drum, hot air, freeze, and spray drying, RWD occurs at a reduced drying temperature, time, cost, and energy usage. This review paper covers recent RWD trends, stressing their impact on process and food quality attributes, as well as the contrasts between RWD and other drying technologies.