Determination of ascorbic acid content of some tropical fruits by iodometric titration
The ascorbic acid content of three common juicy tropical fruits, orange, water melon and cashew, were determined using iodometric titration method under three temperature regimes (refrigerated, room temperature, and heated to about 80 oC), representing the range of temperatures the fruits may be exposed to during processing and storage. It was observed that fruits exposed to higher temperature contained the least of the ascorbic acid. This is as a result of increase in oxidation of ascorbic acid with increase in temperature, as higher temperature favours redox reaction. Refrigerated orange gave an ascorbic acid value of 43.80 mg/cm3, room temperature had 41.84 mg/cm3, while the heated (80 oC) orange contained 39 mg/cm3. Water melon contained 27.30 mg/cm3, 27.05 mg/cm3 and 25.68 mg/cm3 for refrigerated, room temperature and heated fruits respectively. Cashew contained the highest ascorbic acid with 213.62 mg/cm3, 211.79 mg/cm3 and 210.55 mg/cm3 for refrigerated, room temperature and heated fruits respectively.
Keywords: Ascorbic acid, iodometric titration, vitamin C, temperature, orange, water melon, cashew