Mass transfer kinetics and determination of effective diffusivity during convective dehydration of pre-osmosed carrot cubes

The convective dehydration kinetics of un-osmosed and pre-osmosed carrot cubes at drying air temperatures of 55, 65 and 75 degrees C. Prior to convective dehydration, the osmotic pre-treatments were given in solutions of NaCl salt, sucrose and mixtures of sucrose-NaCl. Among the models applied, Middilli model well represented the experimental data for convective drying of un-osmosed and pre-osmosed carrot cubes. Effective moisture diffusivity was estimated using the analytical solution of Fick's law of diffusion and iterative technique, which was conducted by a simple computer program, was used to solve the equation. The program was being executed only for positive values of effective diffusivities. For above said conditions of convective drying, the effective moisture diffusivity was found to be in the range of 7.81 x 10(-10)-10.6 x 10(-10) m(2)/s. The activation energy for the convective drying of carrot cubes was 22.1426 kJ/mole for unosmosed samples, which was 10.0017, 14.8729, 16.2130 kJ/mole in case of NaCl, sucrose, and mixture of sucrose-NaCl salt, respectively. (c) 2006 Elsevier Ltd. All rights reserved.