CONICET | Buscador de Institutos y Recursos Humanos

Peanut skins are a natural source of phenolic compounds with antioxidant property. Some groups of component obtained from crude extract should have higher antioxidant activity. The objective of this study was to evaluate the antioxidant activity of phenolic fractions purified from peanut skins. Peanut skins were obtained by blanching process from Runner peanuts (Argentina). Crude extract (B-Cr) was obtained by solid-liquid extraction from peanut skins using ethanol 70%. B-Cr was partitioned in 2 fractions with ethyl acetate (B-EA) and water (B-W). B-EA was separated by column chromatography (CC) packed with Sephadex LH-20 using ethanol as elution solvent in 3 new fractions: yellow (Y), purple (P), and brown (B). Dry weight yield, total phenolics, and flavonoid content were determined in all fractions. The antioxidant activity of each fraction was determined by DPPH analysis (scavenging activity) and by accelerated oxidation test (60 C) on sunflower oil with 0.02 % (w/w) of each fraction. BHT was used as reference. Peroxide values (PV) in sunflower oil were evaluated during storage. Statistical analysis was performed on the data (ANOVA and LSD test). Dry weight of Y, P, and B fractions were of 4.7, 3.9, and 91.4 %, respectively. Fractions B and P showed higher phenolic content than B-EA. Y had higher flavonoid contents than the other fractions. Fraction P showed higher scavenging activity (IC50=0.65), followed by B (IC50=1.03), and B-EA (IC50=1.58). Y and BHT showed the lowest scavenging activity (IC50=4.70 and IC50=3.94, respectively). Fraction Y exhibited lower PV in sunflower oil followed by BHT, P, B, and B-EA fractions. Peanut skins are rich in phenolic compounds with antioxidant properties. Purification process of peanut skins extracts increased the phenolic content and the antioxidant activity in the fractions. These purified fractions could be used as food additive with functional properties.