Determination of antioxidant activity of polyphenol extract from grape seeds

The aim of the study was to determine the antioxidant property of grape seed polyphenol extract (GSPPE) and compare it with synthetic antioxidant butylated hydroxy toluene (BHT). Canola oil containing 0, 200, 500 ppm of GSPPE and BHT (200 ppm) were subjected to an accelerated oxidation test at 70°C with continuous aeration. Degree of oxidation was monitored at every 48 hours for 8 days using peroxide value (PV) and thiobarbituric acid (TBARS) analysis.; The total phenol content of GSPPE was 43-48% gallic acid equivalent. Regression analyses for the three trials showed PV had a similar pattern of results unlike that of TBARS. The GSPPE 500 ppm showed better antioxidant activity than GSPPE 200 ppm as measured by PV, but the activity was not prevalent throughout the storage period of 8 days. So based on PV, GSPPE 200 ppm and GSPPE 500 ppm are not effective antioxidants when compared with BHT.