Antioxidant activity of phenolic fractions purified from peanut skins

LARRAURI M; ASENSIO, C.; ZUNINO MP; ZYGADLO, J.A.; GROSSO NR; MESTRALLET MG; NEPOTE V

Las Vegas, USA

Congreso; Annual Meeting - IFT 2012; 2012

Institute of Food Technologists

Peanut skins are a natural source of phenolic compounds with antioxidant property. Some groups of component obtained from the 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 two 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 three 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 skin extracts increased the phenolic content and the antioxidant activity in the fractions. These purified fractions could be used as food additive with functional properties. Industry Relevant Information: The shelf-life of food products could be prolonged by the addition of natural preservatives. Peanut skins are a waste from blanched processing of peanut kernels. Phenolic compounds extracted from peanut skins showed remarkable antioxidant activity. These compounds from peanut skins have a considerable potential in the food industry as natural antioxidant to be used in fatty food products to substitute synthetic ones.