Effects of Freeze-drying and Freezing on Vitamins and Sugars of Mango Pulp (‘Apple’ Cultivar): A Preliminary Comparison of Methods for Improving Sample Storage

Abstract

Mango (Mangifera indica L.) fruits are highly perishable ones whose important nutrients such as vitamins and sugars quickly decrease under storage. In this study, we compared two methods of fruit pulp storage; freezing and freeze-drying in order to compare total carotenoids, β-carotene, ascorbic acid (AA), titratable acidity (TTA), total soluble solid (TSS) and pH. Mean total carotenoid, β-carotene and AA of frozen pulp were 7.08±0.15 µg/g, 1.47±0.09 µg/g and 92.77±17.49 mg/100 g respectively. While freeze-dried pulp had 8.06±0.03 µg/g, 2.35±0.03 µg/g and 113.02±0.07 mg/100 g for total carotenoid, β-carotene and AA respectively. The total carotenoid, β-carotene and AA of fresh pulp were; 8.15 µg/g, 2.44 µg/g and 119 mg/100 g respectively. TTA, TSS and pH were; 3.01±1.01%, 9.40±1.42 °Brix and 2.97±0.19 for frozen pulp and 2.97±0.01%, 11.70±0.08 °Brix and 2.99±0.01 for freeze dried pulp respectively. TTA, TSS and pH for fresh pulp were; 4.85%, 11.90 Brix% and 3.48 respectively. All measured parameters were significantly higher (p <0.05) in fresh sample than in the stored pulp (frozen or freeze-dried). Mean total carotenoids, β carotene, AA and TSS were significantly (p <0.05) higher for freeze-dried pulp than for frozen pulp. However, mean TTA and pH did not differ between freeze-dried and frozen pulp. Slow decrease of AA in the freeze-dried pulp further suggests the method as preferred for long term storage of mango pulps.