Spouted bed and microwave-assisted spouted bed drying of parboiled wheat

► Microwave-assisted spouted bed drying reduced drying time siginificantly. ► The drying rate increased with air temperature and microwave power. ► Constant rate period was not observed in drying of parboiled wheat. ► The effect of microwave was dominant rather than the effect of air temperature. The effect of spouted bed and microwave-assisted spouted bed drying on drying rates of parboiled wheat was investigated. In addition, the effective moisture diffusivities of parboiled wheat were calculated. The drying experiments were performed using 200g of parboiled wheat, at three different air temperatures (50, 70, 90°C) and at two different microwave powers (3.5W/g (db), 7.5W/g (db)). Microwave-assisted spouted bed drying at microwave power of 3.5W/g and 7.5W/g reduced drying time by at least 60% and 85%, respectively compared to spouted bed drying. The effective diffusivity values were in the range of 1.44×10−10–3.32×10−10 in spouted bed drying while they were between 5.06×10−10 and 11.3×10−10 in microwave-assisted spouted bed drying at different experimental conditions.