Biochemical Properties and Nutrient Composition of Some Indigenous Tropical Fruits as Affected by Coating/Waxing Preservation

The fruits of avocado (local variety), banana (giant cavendish), cashew (yellow skin variety), mango (Julie variety) and sweet orange (improved variety) at firm ripe stage were obtained, preserved by waxing method and storage effects on biochemical properties, reducing sugar, vitamin C and soluble solid contents investigated. Four different edible fats/oils (animal fat – ANF, Bleached palm oil – BPO, sheabutter – SHB and vegetable oil – VGO) were separately used to wax each fruit commodity in triplicates, including uncoated fruits in storage and fresh samples as control. Then, samples were packaged in perforated plastic baskets, kept in storage at tropical ambient conditions for seven days. After storage moisture, vitamin C, sugar contents, hydrogen ion concentration (pH) and total titratable acidity (TTA) values determined. Moisture losses of 5.3±0.41; 14.7±1.1, 6.2±0.5, 6.7±0.3 and 45.1±1.0% in avocado, banana, mango, sweet orange and cashew apple respectively were recorded by using ANF, SHB and VGO edible fats/oils. On the other hand, moisture losses in the respective uncoated fruits were 22.9±1.9; 23.2±0.9; 66.2±1.5; 9.1±0.3 and 12.7±0.2%. The moisture content loss was based on the original moisture of the fresh fruits. TTA generally reduced among all the preserved fruits regardless of fat/oil used for coating (avocado, 0.010 to 0.014; banana, 0.018 to 0.024; mango, 0.018 to 0.030 and sweet orange 0.016 to 0.039 mg citric/100g) which showed evidence of further ripening during storage. There was also reduction in pH values of fruits which varied among edible fats/oils. The pH values for avocado, banana, mango and sweet orange reduced from 5.94 to 4.05; 5.36 to 4.25; 5.12 to 3.30 and 4.90 to 3.52 respectively. SHB and BPO contributed the least reduction in most of the fruits, showing no significant difference (p < 0.05) between fresh, ripe fruit before storage. Apparently, reduction in total soluble solid and reducing sugar contents of fruit followed the same pattern, while BPO, SHB and VGO contributed the least reduction in banana, mango and sweet orange. Most vitamin C contents 0.084-0.242 mg/100g pulp (65.0-87.5%) were retained in sweet orange, avocado, banana and mango with SHB and BPO. Sheabutter and vegetable oil were found most suitable edible fat/oil as coating agent for retention of moisture, vitamin C, soluble solids and preservation of freshness of ripe banana, sweet orange, avocado and mango for the purpose of shelf - life extension to prevent spoilage during distribution prior to consumption.