Effects of microwave - fluidized bed drying on quality, energy consumption and drying kinetics of soybean kernels

• Published in: Journal of food science and technology 2015-08, Vol.52 (8), p.4749-4760
• Main Authors: Khoshtaghaza, Mohammad Hadi, Darvishi, Hosain, Minaei, Saeid
• Format: Article
• Language: English
• Subjects: Air flow; Air temperature; Analysis; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Drying; Energy consumption; Fluidized beds; Food; Food preservation; Food processing industry; Food Science; Humidity; Microwaves; Moisture content; Nutrition; Original; Original Article; Soybeans; Studies; Temperature; Velocity
• ISSN: 0022-1155; 0975-8402
• DOI: 10.1007/s13197-014-1557-6

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.