Effects of fluidized bed drying on the quality of soybean kernels

The effects of air temperature and velocity on the drying qualities (cracking, bulk density, shrinkage and rehydration) of soybean kernels in fluidized bed dryer were investigated. Drying was carried out at 80, 100, 120 and 140 °C and air velocity of 1.8, 3.1 and 4.5 m/s. Soybean kernels were dehydrated from the initial moisture content of 25% (w.b) to a final moisture content of 10%. The drying evaluation showed that high drying temperature and air velocity resulted in high cracking and low rehydration ratios (P < 0.05). However, air velocity had no significant effect on bulk density and shrinkage of soybeans. By increasing the temperature and air velocity over their full ranges, drying time decreased from 380 to 50 min. Cracking, bulk density, degree of shrinkage and rehydration ratio varied from 31.80% to 58.22%, 1101.31 to 1186.39 kg/m3, 0.730 to 0.787, and 0.583 to 0.873, respectively. Regression equations were established which can be used for the estimation of the quality parameters as a function of the drying variables.