Optimization of the osmotic dehydration of mango (Mangifera indica L.) slices

Fresh mango (Mangifera indica) slices were osmotically dehydrated using four treatment variables: treatment time, temperature, sugar concentration and slice thickness. Treatment times for 2, 4 and 6 mm slice thickness were 3, 5 and 7 h at temperatures of 20, 30 and 40degreesC and sugar concentrations of 40, 50 and 60% (w/w). The responses variables tested were weight reduction (WR), sugar gain (SG), final moisture content (M-f) and overall product acceptability (OA). A fractional factorial design (3 level-4 parameter) with 27 runs was used as the experimental design. A Response Surface Methodology (RSM) was performed to analyze and predict the optimum conditions of the mango osmotic dehydration process. All treatment variables significantly affected WR, while SG and M-f were significantly affected only by thickness. On the other hand, none of the variables showed no significant effect on the OA. The optimum conditions were determined with the following response limiting values: at least 30% WR, at least 8% in SG, M-f of not exceeding 70% were based on previous studies and panel evaluation results. The optimum conditions generated were: treatment time of 6h, temperature of 35degreesC, sugar concentration of 65% (w/w) for 5mm slice thickness. Results of validation tests were fairly acceptable since the Coefficient of Variation (CV) of the responses were less than 15% except for sugar gain with a 26.5% CV.