Kinetics of Mass Transfer during Osmotic Dehydration of Banana Slices

Osmotic dehydration process is one of the drying methods which commonly used for fruits and vegetables. The objective of this work was to study the mass transfer kinetics phenomenon duringosmotic dehydration of bananas slices, as well as evaluate the effective diffusion coefficient ofwater, based on an analytical solution of Fick’s second law. Fresh bananas were obtained from thelocal market. Six different mixtures of sucrose and NaCl dissolved in distilled water were used as osmotic agents. The experiments were performed in a shaker at intervals of 1.5, 3, 4.5, 6, 7 hr. The governing equations of this process, were solved analytically and effective diffusion coefficient was found for each of experiments. The results showed that moisture loss increased with time nonlinearly at all concentrations. Also water loss increased with increase in sucrose solution from 50°B (Brix index) to 60°B with salt percents of 0%, 5% and 10%. Water loss values for 50°B and 60°B after 6 hours osmosis were 21.5%, 27.75% in 0% salt , 38.5%, 39.75% in 5% salt and 41.75%, 46.5% in 10% salt, respectively. In addition, the results indicated that the effective diffusion coefficient of water varied from 5.67×10-9 to 9.11×10-9 m2/s.

Keywords:

Osmotic Dehydration , Mass Transfer , Effective Diffusion Coefficient , Banana