Moisture content of soybean kernel at harvest time is too high for storage, and needs to be reduced. In this research, drying characteristics, quality and energy requirement for microwave-fluidized bed drying of soybean kernels were studied. The results showed that air temperature (80-140 °C), velocity (1.8-4.5 m/s) and microwave power (200-500 W) significantly influenced drying time, moisture diffusivity, rehydration capacity, cracking, and specific energy consumption (P ≤ 0.05). Among the applied models, Page's model has the best performance to estimate the microwave-fluidized bed drying behavior of the soybean kernels. Moisture diffusivity values increased (6.25 × 10(-10) to 42.14 × 10(-10) m(2)/s) as the air velocity decreased and air temperature and microwave power increased. Activation energy was foundto be between 3.33 and 17.70 kJ/mol. Minimum cracking percentage of soybean kernels (12.96 %) was obtained at 80 °C, 1.8 m/s and 200 W treatments. The increase in microwave power and decrease in air velocity level decreased the rehydration capacity. Specific energy consumption varied from 50.94 to 338.76 MJ/kg water and the lowest specific energy consumption were obtained at 80 °C, 4.5 m/s and 500 W.
Keywords: Cracking; Energy consumption; Microwave-fluidized bed drying; Rehydration; Soybean kernel.