Kinetic Modelling of Vitamin C Degradation in Selected Fruits under Market Storage Conditions

The degradation kinetics of vitamin C in three fruits namely; orange, banana and apple under different market storage conditions prevalent in Nigeria were investigated. Orange and banana samples were stored in sacks and open air at ambient conditions, while open air and refrigerator were used for apple samples. Storage was for 6 days duration. .Iodometric titration was used to determine vitamin C content of the fruits on a daily basis. Regression analysis was employed to fit the variations in vitamin C concentration in the different samples with time, to three kinetic models, to determine which model best describes the degradation trend. Results showed that vitamin C concentration in all the fruit samples reduced over time following zero order kinetics. Kinetic studies obtained the following degradation rate constants: orange 0.44g.L-1.s-1 and 0.29 g.L-1.s-1, for sack and open air storage respectively, banana 0.316 g.L-1.s-1 and 0.264 g.L-1.s-1, for sack and open air, and apple 0.122 g.L-1.s-1 and 0.188 g.L-1.s-1, for refrigerated and open air respectively. The study indicated that with respect to vitamin C retention, open air storage is preferable to sack for oranges and bananas while apples are preferably stored in refrigerator.