Effect of Osmotic Dehydration and frozen Storage on Quality Characteristics of Mango Slices

Osmotic dehydration (OD) is one of the promising preservation technique for dehydrated foods, especially fruits and vegetables and it has some benefits such as reducing heat damage to the color and flavor, inhibiting enzymatic browning and reducing energy cost. The study was conducted to determine the effect of osmotic dehydration and frozen storage on quality characteristics of mango slices. The mango slices were prepared by using different concentration of sucrose. For this purpose, dussehri variety of mango was used. For three ripening levels, three levels of sucrose solutions (10, 20 and 30°Brix) were used for the osmotic treatments. Proximate analysis of mango slices was done before and during storage period for 10 days of interval and physico-chemical analysis was carried out to determine the pH, color, ascorbic acid, water activity, total soluble solids, reducing, non-reducing and total sugars. Osmotic dehydration was able to modify quality parameters of slices before and after frozen storage. However, treatments carried out with osmotic solutions (especially those with high concentrations of sucrose) improved significantly the quality of mango slices after frozen storage. Higher moisture losses and solid gain values were reported for slices from the highest osmotic solution concentration. Moisture content decreased from 87.6 to 73.7% while protein, fat and ash content increased from 0.88 to 0.89%, 0.31 to 0.33% and 0.493 to 0.5% respectively. Some physico-chemical parameters decreased from 0.4738 to 0.306, 0.982 to 0.978, 17.76 to 16.68%, 15.49 to 10.48% and 19.03 to 11.78 mg citric acid/ 100 g pulp respectively for titratable acidity, water activity, total sugar, non-reducing sugar and ascorbic acid while pH increased from 2.85 to 3.19. Firmness and lightness decreased from 3543.9 to 2492.7g and 52.39 to 49.49 respectively. Thus, slices dipped in 30°Brix were better protected against freezing damage. The effect of sucrose concentration on the slices and ripening stages on frozen mango flavor perception were determined. Four flavor descriptors (color, texture, appearance and overall acceptability) were evaluated by a sensory trained panel. The results obtained from all the parameters were subjected to statistical analysis.