Evaluation of water, sucrose and NaCl effective diffusivities during osmotic dehydration of banana (Musa sapientum, shum.)

Osmotic dehydration of banana (Musa sapientum, shum.) was optimized with respect to temperature (25–55 °C), salt (0–10 g/100 g) and sucrose (30–60 g/100 g) concentrations through response surface methodology. The solution of Fick’s law for unsteady-state mass transfer in a cylindrical configuration was used to calculate the effective diffusivities of water, sucrose and NaCl. Analyses were conducted in triplicate for moisture, sugar and salt contents. Peleg’s model was used to predict the equilibrium condition, which was shown to be appropriate for water loss and solute uptake. For the above conditions of osmotic dehydration, the effective diffusivity of water was found to be in the range of 5.19–6.47 × 10−10 m2 s−1, the sucrose effective diffusivity between 4.27–6.01 × 10−10 m2 s−1 and that of NaCl between 4.32–5.42 × 10−10 m2 s−1. The working conditions that simultaneously optimize these 3 variables were the temperature of 25 °C with a solution composed of 30 g/100 g of sucrose and 10 g/100 g of sodium chloride. This condition provided values of 4.80 × 10−10 m2 s−1 for effective diffusivity of water, of 3.21 × 10−10 m2 s−1 for effective diffusivity of sucrose and 4.49 × 10−10 m2 s−1 for effective diffusivity of sodium chloride.