Mass transfer kinetics and optimization during osmotic dehydration of beetroot (Beta vulgaris L.)

The present study was carried out to investigate the mass transfer kinetics and optimization during osmotic dehydration of beetroot. The samples were osmotically treated in different hypertonic sugar solution (55, 65 and 75 0 Brix) with salt concentration of 5 % (w/v), at different solution temperature (30, 45 & 60 °C). Mass transfer kinetics was modeled according to Magee and Azuara model, and kinetic parameters were calculated. It was found that the magee’s model was appropriate for predicting water loss (WL) and solute gain (SG), while Azuara’s model fitted water loss as well as solute gain (SG) data represented more accurately the condition of the complete process close to equilibrium. Quadratic regression equations describing effects of process variables on water loss, solute gain and weight reduction were developed and optimization of osmotic dehydration was done using response surface methodology (RSM). The regression analysis revealed that linear terms of all process parameters have a significant effect on all the responses. The optimum conditions were found to be as sugar of 75 0 Brix with 5% salt, solution temperature of 47.70 0 C and immersion time of 120 min at constant osmotic solution to sample ratio of 4:1. At these optimum values, water loss, solute gain and weight reduction were observed as 28.78, 4.42 and 24.36 (g/100 g of initial mass) respectively. Index Terms Beetroot, osmotic dehydration, mass transfer kinetics, modeling, and optimization