Mathematical modeling of packed bed and microwave drying of enriched couscous

In this study, the drying kinetics and modeling of enriched couscous with two different compositions (A and B) were carried out by using packed bed (60 and 80 A degrees C) and microwave (180 and 360 W) drying techniques. Seven drying models were used to determine the best fitting of experimental data. Moreover, the effects of drying methods and parameters on color, yield and sensory attributes of enriched couscous were evaluated. It was found that microwave intensity increment is more effective on drying rate and drying time in contrast to the increment of drying air temperature in the packed bed drying. The free moisture contents of the enriched couscous decreased with time. The effective moisture diffusivities of enriched couscous produced with composition A and B were between 0.93 x 10(-8) to 1.68 x 10(-8) and 0.86 x 10(-8) to 1.42 x 10(-8) m(2) s(-1), respectively. Midilli and others model for the packed bed and microwave drying was observed to be the most suitable for the experimental data with the highest values of R-2, and the lowest values of RMSE, chi(2) and RSS.