Abstract
varieties (white and red) and some quality characteristics were also examined. The experimental data obtained at drying temperatures of 40, 50 and 60 oC, and thicknesses of 2, 4 and 6 mm, were subsequently fitted into four commonly used models (Henderson and Pabis, Lewis, Page and Logarithmic). The moisture diffusivity and activation energy ranged from 8.91 × 10-10 - 8.39 × 10-9 m2/s and 55.98 - 65.68 KJ/mol, respectively. Significant differences (p <0.05) were observed in the color profile and rehydration ratio. The optimum desirable color was obtained at 50 oC with 2 mm thickness onion slices and the observed higher rehydration ratio indicates good quality of dried onions. Among the four selected drying models, Page model predicted optimally (R2 > 0.9) and was found to better in describing dried onion varieties, while Lewis model gave the least fit.