In this research the drying of four kinds of vegetables was investigated in a vacuum dryer.The effect of temperature on drying rate of samples at various temperatures (30, 35 and 45oC) was studied. Six thin-layer drying models were fitted to drying data and suitable model was selected from them. Then effective moisture diffusivity and activation energy of samples were calculated.The Diffusion approximation model gave excellent fit for fenugreek and mint leaves and vegetative parts of leek and the page model was considered adequate to describe the thin-layer drying behavior of parsley leaves. The effective diffusivity values changed from 2.92x10 -10 to 9.81x10 -10, 1.77x10 -10 to 5.99x10 -10, 9.3x10 -11 to 1.7x10 -10 and 1.27x10 -9 to 3.4x10 -9 for fenugreek, mint and parsley leaves and vegetative parts of leek, respectively. An Arrhenius type of equation was used to evaluate the effect of temperature on the effective diffusivity and the activation energy values was found 66.36, 66.34, 32.27 and 51.16 kJ/ mol for fenugreek, mint and parsley leaves and vegetative parts of leek, respectively.

Vacuum drying of Salicornia herbacea L. was performed at different drying temperatures (50, 60, 70, and 80oC) to evaluate the drying characteristics and the effect of drying temperatures on the quality of Salicornia. As the drying temperature increased, the drying time decreased significantly (P< 0.05). The drying rate decreased with decrease in moisture content and increase in drying time. On the other hand, the drying rate increased with increase in drying temperature. The logarithmic model exhibited the best fit to the experimental drying data among the tested models. The drying constants estimated using the logarithmic model were found to be affected by the drying temperature. The activation energy for drying was 15.02 kJ mol-1. The surface color of the Salicornia herbacea samples was significantly affected by the drying temperature (P< 0.05). CIE L*-, b*-, and Chroma (C*)-values increased significantly, while a*- and hue angle (h*)-values decreased significantly after drying at all of the drying temperatures (P< 0.05).