Evaluation of drying kinetics, energy consumption, thermo-physical characteristics, and color quality of sweet cherries dried in an active-passive indirect dryer

Since cherries are a seasonal product, it is not possible to obtain them at all times of the year. Due to their high moisture content, they cannot be stored for long periods of time. For these reasons, the drying of sweet cherries is of great importance in preventing product losses and preserving market value. In this study, cherries were dried with different solar energy using passive (without fan; P1), active (with three fan speed; F1, F2, F3) and open (exposed to the sun) methods in order to extend the shelf life and provide access in all seasons. The kinetics of the drying processes, energy consumption parameters, thermophysical properties and their effects on color parameters were investigated. Drying rate in drying processes changed in the range of 6.09–13.98 × 10−4 g moisture/g dry matter min. It was determined that effective moisture diffusion values ranged between 1.43 × 10−8–9.62 × 10−9 m2/s. The highest average specific heat, thermal conductivity, thermal diffusivity and specific mass of the dried samples were obtained at activated type-F1 fan speed. The dry product closest to fresh according to all color values was determined in the open drying method. According to the results, it is recommended that solar drying at a single fan speed (F1) be prioritized as a promising approach for sweet cherry drying in future applications and studies, while further optimization of active systems can improve specific moisture extraction rate (SMER) and specific energy consumption (SEC) performance.