FUZZY AND CONVENTIONAL MODELING OF OPEN SUN DRYING KINETICS FOR ROASTED GREEN WHEAT

Roasted green wheat is a high-value product made by roasting green (under-mature) wheat. Due to its high initial moisture content, drying is needed to avoid fast deterioration. Open sun drying of this product is by far the most common practice due to its simplicity, effectiveness, and low cost. The assumption of open sun drying adequacy to prevent deterioration was tested in this study. The drying data were fitted into eight common thin-layer drying models. Goodness of fit for each model was evaluated using coefficient of determination (R-2) and root mean square error. The two-term exponential model was found to best describe open sun drying of roasted green wheat with R-2, and root mean square error values of 0.988 and 0.038, respectively. A fuzzy model of open sun drying for roasted green wheat was also developed and compared with conventional modeling. The results showed a much better performance of fuzzy model compared to conventional models with a much lower value of root mean square error (1.2 x 10(-6)). The effective diffusivity was also evaluated for roasted green wheat kernels and found to be 1.7 x 10(-11) m(2)/s, which was in agreement with published data. The results showed that open sun drying for 5.5 h was effective and adequate to reduce moisture content to a safe level and to prevent deterioration of this product. These findings will provide valuable information for the design of a commercial roasted green wheat solar drying system.