Controlling surface temperature in Intermittent Microwave Drying of potato slices using evaporative cooling: An experimental study

Abstract

A new method to control the surface temperature of biomass during Intermittent Microwave Drying (IMWD) is proposed in this study. The feedback-based drying method involves rewetting the food surface during drying to maintain its temperature below a certain threshold. The surface of potato slices was artificially rewetted during IMWD at different threshold temperatures for experimental validation. Containing the temperature at lower levels improved the cosmetic and nutritional quality of food. It was found that artificially rewetting the surface of potato slices when their temperature exceeded 60 °C reduced the average surface temperature by 16%. While it increased both drying time and specific energy consumption by 40%, the dried potato retained 14.2% more Vitamin C and 13.4% better color characteristics compared to the control sample. The textural quality was also improved. It was found that slices that were maintained below a lower surface temperature showed a 52.2% higher increase in hardness compared to the control sample, and they retained 43.1% more cohesiveness, resulting in harder and more mechanically stable dried slices. The study revealed that this method of drying resulted in a significantly improved nutritional, cosmetic, and textural quality of the product.