Drying Kinetics of Steamed Glutinous Rice with a Free Convective Solar Dryer

Abstract

The drying kinetics of steamed glutinous rice with a free convective solar dryer was studied and compared with open sun drying. The color of the dried product was also evaluated. The drying behavior of the steamed glutinous rice formed in the short cylindrical shape, known as Kao-Tan, from 100 % dry basis to a constant moisture level was investigated. Several drying models, namely Newton, Page, Henderson & Pabis and the Two term exponential were fitted to the data for both drying methods. The experimental results showed that solar dryer provided a higher air temperature and higher drying rate than open sun drying. The drying rate depended on the air temperature. The color comparison of the dried products between the 2 drying methods revealed that the solar dryer led to a significantly lighter, less red and less yellow product than that dried by open sun drying. From this study it can be concluded that a free convective solar dryer can be used to produce dried steamed glutinous rice well. Finally, the best drying model was Henderson & Pabis, whose model parameters was functioned with drying air temperature.