Extraction, Characterization and Antioxidant studies from Grape peel

Abstract

This research is aimed at extracting, characterizing and investigating the antioxidant potential of grape peels in solving the problem associated with lipid oxidation in food. Grape peel sample was collected and oven dried at 60 for 48 hours, after which it was grinded and sieved to a particle size of 500 µm. Extracts were estimated from grape peel using methanol as solvent in a soxhlet extractor at different solid - solvent ratio, temperature and extraction time. The optimum conditions of the solid-solvent ratio, temperature and time obtained for the grape peel extract were 10: 200, 55 and 180 minutes respectively. The grape peel extract obtained at the optimum conditions was then characterized using Atomic Absorption Spectrophotometer to identify both the major and minor elements present. The elemental analysis of the grape peel extract confirmed potassium as the major element by percentage composition of 90.1. In assessing the effect of the grape peel extract on the mixture of cow fat and groundnut oil sample, oxidation stability of the oil sample with and without the extract were analysed using Rancimat test. The oxidation stability of the oil mixture samples mixed with and without the grape peel extracts were found to be 569 minutes and 67 minutes respectively. This clearly showed that the grape peel extract is effective in increasing the possible time by which oxidation process can take place within the oil sample from 67 to 569 minutes. In addition, peroxide, pH and free fatty acid tests of the oil mixture with and without grape peel extract were carried out and antioxidant effectiveness of the grape peel extract calculated. The results obtained clearly confirmed the potential ability of grape peel as an antioxidant agent.