Study of mass transfer kinetics and effective diffusivity during osmotic dehydration of carrot cubes

The mass transfer kinetics during osmotic dehydration of carrot cubes in ternary solution of sucrose, NaCl salt and water were studied. The osmotic solution concentrations used were 50 °B + 5% salt (w/v), 50 °B + 10% salt (w/v) and 50 °B + 15% salt (w/v), osmotic solution temperature used were 35, 45 and 55°C, fruit to solution ratios 1:4, 1:5 and 1:6 and the process duration varied from 0 to 240 min. Among the models applied, Azuara model well represented the experimental data for water loss; whereas solute gain was well represented by the Magee model. Effective diffusivity of water as well as solute 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 with first six terms. For above conditions of osmotic dehydration, the effective diffusivity of water was found to be in the ranged between 1.594 × 10−9 and 2.078 × 10−9 m2/s and that of solute between 1.175 × 10−9 and 1.645 × 10−9 m2/s.