Influence of Convective Drying Temperatures on the Moisture Removal Kinetics and Physicochemical Characteristics of Japanese Persimmon (Diospyros kaki) Peel Powders

Persimmon peel is an excellent source of antioxidants, phenolic compounds, and other phytochemicals, making it a valuable byproduct rather than a food waste. This study evaluates the effects of air-drying temperatures from 40 to 70°C on the drying kinetics, physico-chemical properties, color, yield, turbidity, particle morphology, thermal stability, functional groups, antioxidant capacity, and total phenolics of persimmon peel. Drying was conducted at air temperature between 40°C to 70°C with a constant air velocity of 2.7 ms ^− 1 . The results indicated that higher air temperatures led to a decrease in drying time with the process occurring primarily during the falling rate period. Seven thin-layer drying models were analyzed using the coefficient of determination and root mean square error, and the Weibull model was determined as the best fit for characterizing the drying kinetics of persimmon peel. The antioxidant capacity dropped while the overall phenolic content increased with higher drying temperatures. Although drying temperatures did not have a significant effect on morphological and functional characteristics and thermal stability, the color changes were noticeable. Despite the larger color changes, 60°C produced the optimum combination of antioxidant and phenolic chemicals.