Drying rate for solar-assisted spouted bed was as high as nearly 3.5 times as open sun drying (Fig. 3). The rate difference was due to the temperatures of drying and also mobility of particles during spouting as explained before. Furthermore, during both drying methods only falling rate period was observed, indicating that the mechanism in drying was diffusion controlled. More than one falling rate periods was observed as in the case of the study of Simal et al. (1996) for drying of green peas. During falling rate period, sample surface is not wet enough for keeping constant rate and moisture content starts to decrease continuously (Geankoplis, 2003).