Impact of process variables on effective moisture diffusivity during convective drying of Osmotically dehydrated mushroom samples

Abstract

The drying characteristics of osmosed mushroom slices were investigated in an experimental axial flow dryer at various air temperatures of 45, 55, 65, 75 and 85oC and velocity of air such as 1.0, 1.5 and 2.0 m/s. The entire drying process took place in the falling rate period. Effective moisture diffusivity (Deff) was determined for examined temperatures and velocities using Fick’s second law of diffusion adapted to slab geometry. The calculated effective moisture diffusivity of osmo-convectively dried mushroom samples varied considerably with moisture content and air drying temperature from 1.39 x 10-9 to 4.67 x 10-9, 1.44 x 10-9 to 4.81 x 10-9 and 1.57 x 10-9 to 4.92 x 10-9 m2/s for air velocity of 1.0, 1.5 and 2.0 m/s, respectively. Activation energy was also calculated and found to be 26.69, 27.91 and 29.26 kJ/mol for 1.0, 1.5 and 2.0 m/s air velocity respectively.