Optimization of osmotic dehydration of apple in sugar beet molasses

Abstract

Osmotic dehydration is an environmentally acceptable, material gentle drying process, which received considerable attention because of the low processing temperature, base waste material and low energy requirement. Response surface methodology (RSM) was used to determine the optimum processing conditions that yield maximum water loss and dry matter content and minimum solid gain and water activity during osmotic dehydration of apple in sugar beet molasses, and that reduce energy requirements for the process, on the other hand. Temperature (45-65°C), processing time (1-5 h), molasses concentration (40-80%) were the factors investigated with respect to water loss, solid gain, dry matter content and water activity. Experiments were designed according to 33 full factorial experimental designs with these three factors each at three different levels. For each response, second order polynomial models were developed using multiple non-linear regression analysis. Analysis of variance (ANOVA) was performed to check the adequacy and accuracy of the fitted models. The response surfaces analysis showing the interaction of process variables were constructed. Using Maple 13 Software optimum operating conditions were found to be at temperature of 45°C, molasses concentration of 80%, and treatment time of 222 min. At this optimum point, water loss, solid gain, dry matter content and water activity were found to be 0.6628 (g/g initial sample weight), 0.1156 (g/g initial sample weight), 49.34% and 0.879, respectively.