A COMPARATIVE ANALYSIS OF VITAMIN-C CONCENTRATION IN COMMERCIAL FRUIT JUICES AND FRESH FRUITS OF NEPAL WITH EFFECT OF TEMPERATURE

Abstract

Objective: It was aimed to determine the best storage temperature for fruits to achieve the highest quality of vitamin-C and to compare vitamin C concentration between commercial fruits juices and fresh fruit juices in by using Spectrophotometry and Titrimetric method

Methods: Titration involved the redox reaction between iodine and vitamin C. As the iodine was added during the titration, the ascorbic acid was oxidized to dehydroascorbic acid, while the iodine was reduced to iodide ions. The Spectrophotometric method involved the coupling reaction of 2,4 dinitrophenylhydrazine (DNPH) dye with Vitamin C. The samples were analyzed using UV-Vis-Spectrophotometer at 521 nm.

Results: Titrimetric and spectroscopic methods were performed for fresh and marketed fruits comprising of apple, grapes, lemon, orange. The maximum amount was found in lemon and orange whereas apple and grapes contained lesser amount of Vitamin C. The stability of marketed fruit juices made up of apple, grapes, lemon, orange were analyzed by storing them on the freeze at 0 °C and 10 °C and on the hot air oven at 20 °C, 30 °C, 40 °C, 50 °C for 72 h and estimated by both Titrimetric and Spectroscopy method. UV-Spectroscopy method showed that, at freezing condition up to 10 °C temperature, degradation was too low but when the temperature reached 50 °C the extent of degradation was more, showing 24.56% apple juice, 10.89% orange juice,12.70% grapes juice and 50% orange juice were degraded in 100 ml sample. Similar results were observed by analysing the samples with titration technique.

Conclusion: A new analytical method was developed to address the content of vitamin C in fruits consumed in the local market of Nepal along with the best possible storage of fruit juice to yield the maximum amount of nutrients.