Osmotic Dehydration of Orange Fruits in Sucrose and Prickly Pear Molasses Solutions: Mass Transfer and Quality of Dehydrated Products

The osmotic dehydration of orange fruit slices in sucrose and prickly pear molasses was studied in order to examine the changes in total mass loss, water loss, and solid gain as well as physical properties (dry matter content, total soluble solid and color parameters) during this process. The contents of total phenolics, ascorbic acid, and sugars, as well as antioxidant capacity and texture parameters of fresh orange slices and these dehydrated in both solutions were also analyzed. The osmotic dehydration was carried out at a temperature of 30°C for 3 h and after this processing time, the total mass loss of orange slices dehydrated in molasses solution was higher (0.18 kg/kg) compared to that treated in a sugar solution (0.16 kg/kg). Throughout the process, higher ratios of water loss to solid gain were noted for orange slices dehydrated in molasses solution than in the sucrose one. No significant difference was found in water activity between orange slices dehydrated in both solutions. Molasses induced more substantial and perceptible color alterations in orange slices compared to sucrose with total color difference values of 9.12 and 3.28, respectively. Immersion in osmotic solutions reduced hardness of orange slices from 0.63 N for fresh slices to 0.52 N and 0.40 N for these dehydrated in sucrose and molasses solutions, respectively. Compression work values of dehydrated orange slices were 0.38 mJ after the treatment in a sucrose solution and 0.36 mJ in the molasses one. The total phenolic content, antioxidant capacity in ABTS assay and ascorbic acid content increased in dehydrated slices compared to fresh material, particularly in the slices processed in molasses (2,197 mg CA/100 g DM, 6.26 mg Trolox/g DM and 50.14 mg/100 g, respectively). Sugar profiles of dehydrated orange slices varied, with molasses favoring glucose (5.47 mg/100 g DM) and reducing fructose (1.80 mg/100 g DM) compared to sucrose. Prickly pear molasses could be incorporated into the preservation of seasonal fruits as a valuable osmotic solution.