The antioxidant ability of grape seed extracts

摘要

The study was carried out to evaluate the antioxidant activity of grape seed extracts by measuring acid value, peroxide value (POV), thiobarbituric acid reactive substances (TBARS value) and electron donating ability by 1,1-diphenyl-2-pycryl hydrazil (DPPH) method. Total phenol content of freeze dried crude solvent extracts increased in the order of ethanol>acetone>hot water. Among extracts, the total phenol content of 70 percent ethanol extract of grape seed (GSE) was the highest, 51 percent. Besides the total phenol, the other major components of GSE were crude carbohydrate (29.63 percent), crude protein (3.38 percent) and crude lipid (2.84 percent). The acid values of crude rice bran oil containing GSE or several antioxidants at the concentration of 0.01 percent were 52.3 for the control, 0.5 for GSE, 2.3 for dibutyl hydroxytoluene (BHT), 45.0 for tertiarybutyl hydroxy quinone (TBHQ), 29.9 for tocopherol and 37.7 for ascorbic acid. The POVs for linoleic acid methyl ester in the presence of 0.01 percent antioxidants were 1220 meq/kg in control, 55 meq/kg in GSE, 104 meq/kg in BHT, 952 meq/kg in tocopherol and 71 meq/kg in ascorbic acid. The antioxidant activities for TBARS (percent) in the presence of 0.01 percent antioxidants were 53 percentin GSE, 37 percent in BHT, 37 percent in tocopherol and 52 percent in ascorbic acid. The electron donating abilities by DPPH in the presence of 0.01 percent antioxidants were 95.3 percent in GSE, 75.0 percent in BHT, 96.3 percent in tocopherol and 98.2 percent in ascorbic acid. These results indicated that the antioxidants activities of GSE were significantly higher than those of several antioxidants compared.