Efficiency of grape seed extract (GSE) on inhibition of lipid oxidation of soybean oil in comparison to butylated hydroxytoluene (BHT) was studied. Grape seed was extracted with ethanol 80% and total phenolic content was (90.26 mg/100gs dry weigh). 2, 2-diphenyl-picrylhydrazyl (DPPH) radical scavenging activity was used to assess the antioxidant efficacy of GSE. HPLC analysis of GSE sample showed that the extract contained phenolic acid such as gallic acid, caffeic acid, m-hydroxy benzoic acid and coumaric acid. GSE was examined for antioxidant activity under accelerated oxidation condition using soybean oil as oxidation substrates at different concentrations (200, 400, 600, 800 and 1000 ppm) for 10 days at 70˚C. Inverse relationships between peroxide values and oxidative stabilities were noted and also between secondary oxidation products. Conjugated dienes and conjugated trienes were increased gradually with the increase of storage time. Results indicated that GSE exhibit stronger antioxidant activity than butylated hydroxytolune (BHT).The obtained result inducted that GSE has great potential to be used as a natural antioxidant.
Keywords: Antioxidant activity; Grape seed extract; phenolic acid; Lipid oxidation