Mathematical Modeling of Mass Transfer Phenomena of Sucrose Molecules During Osmotic Dehydration of Star Fruit

Star fruit (Averrhoa carambola L.) is an Asian fruit widely consumed in eastern Peru. The objective of this study was to quantify mass transfer during osmotic dehydration of star fruit using mathematical modeling. Slices of 8 mm thickness were used and the fruit-to-solute ratio was 1:3. The duration of the process ranged from 0 to 420 minutes. The effects of two process variables were evaluated: syrup concentration (50°, 60° and 70° Brix) and dehydration temperature (40°, 50° and 60°C). The experimental data on water and sucrose transfer were fitted to linear, polynomial, exponential and logarithmic mathematical models. The model with the best goodness of fit was selected based on the correlation coefficient R^2. The results showed that the quadratic polynomial model successfully predicted solute gain and water loss. The diffusion coefficient was quantified using Crank's model with logarithmic fit, and Peleg's mathematical model was fitted to the moisture loss in the fruit. Sucrose diffusion was maximum at 70 °Brix and 60 °C, while water loss was maximum at 70 °Brix and 60 °C. In the Peleg model of water loss, the highest initial water transfer rate was obtained at 50 °Brix and 60 °C, and the lowest equilibrium moisture content was obtained at 70 °Brix and 60 °C. Higher temperatures and sucrose concentrations were observed to lead to higher diffusion rates for water loss and sucrose gain in star fruit.