Optimization of Refractance Window Drying for Nutrient-Rich Mushroom Slices: A Comparative Study With Convective and Solar Drying

Abstract

This study aimed to optimize the drying parameters for mushroom slices using the refractance window drying (RWD) method, addressing the challenge of preserving both the quality and efficiency of drying in mushroom processing. By evaluating various pretreatment options and refining the drying conditions, the research sought to identify the most effective approach for enhancing the physico-chemical parameters of the dried mushroom slices. The effects of water temperature (70°C, 80°C, and 90°C), slice thickness (2, 4, and 6 mm), and potassium metabisulphite (KMS) concentration (0.5%, 1.0%, and 1.5%) were analyzed for the same. The highest drying rate was achieved with 2 mm slices at 90°C, with rates decreasing as temperature lowered or slice thickness increased. Using a Box-Behnken design in response surface methodology (RSM), the optimal parameters were identified as 90°C water temperature, 6 mm slice thickness, and 1.01% KMS concentration. The best results for total color difference, phenolic content, bulk density, antioxidant activity, and protein content were found in RWD samples. Compared with three-stage convective tray drying and solar drying, RWD produced samples with superior drying rates, lower moisture, better rehydration, and higher protein and antioxidant content, especially for pretreated samples.