Effect of humidified hot air fluidized-bed drying On quality of partial parboiled rice

Abstract

This research aimed to experimentally investigate quality of paddy dried by hot air and humidified hot air fluidization technique. Quality such as head rice yield (HRY), degree of crystallinity and color of dried paddy were evaluated. The paddy (Chainat 1) with initial moisture content of 14% d.b. was soaked in hot water at temperature of 70 degree Celsius for 5 hours. Then the soaked paddy was dried in a fluidized bed dryer using a humidified air at dried air temperature of 150 degree Celsius, an air velocity of 4.0 m/s and a bed height of 10 cm. The results showed that when the drying time of paddy in a humidified air drying was taken longer than that in hot air drying. The amount of head rice yield obtained from the humidified hot air was relatively higher than that of hot air drying. The whiteness index (WI) of humidified hot air samples was darker when compared with the color of hot air dried samples. From the XRD analysis, the humidified hot air sample showed a lower percentage of crystallinity than that of the hot air dried product.