Chemical Composition and Antioxidant Activity of Peanuts Skin Extracts Obtained From Virginia and Runner Varieties

BARRIONUEVO G.; GROSSO, N.R.; OLMEDO R. H.; NEPOTE, V.

Chicago

Congreso; IFT 2015; 2015

Institute of Food Technology

Peanut skins have phenolic compounds with antioxidant properties and could be used as a source of natural antioxidants. The objective of this work was to compare the efficiency, chemical composition, and antioxidant activity of skin extracts obtained from two peanut varieties. Peanut skins were prepared by blanching process from kernels of Runner (R) and Virginia (V) peanut varieties. Phenolic extracts were obtained by solid-liquid extraction from defatted peanut skins using ethanol-water 70-30. The chemical composition of R and V peanut skins and their extracts was determined (fat, protein, moisture, ash, and carbohydrate contents). The extraction yields, total phenol, and flavonoid contents and free radical scavenging activity (DPPH) were determined on R and V peanut skin extracts. An accelerated oxidation test on sunflower oil with R and V extracts (0.2%) was conducted at 60 °C. Also a control sample (sunflower oil without additives) and a comparative reference (0.02% BHT) were prepared. Peroxide values and conjugated dienes were determined in oil samples removed from storage. Data were analyzed by ANOVA and LSD test. R skins exhibited higher ash and lipid contents, and lower total carbohydrate than Virginia peanut skins. V skins showed high phenolic extraction yield (18.96%) than R skins (10.96%). V extract resulted with higher phenol (1214.50 mg/g) and flavonoid (78.48 mg/g) contents than R extract (726.60 and 76.31 mg/g, respectively). V and R extracts did not showed significant differences in radical scavenging activity (IC50 4.44 and 4.06 µ g/mL, respectively). R and V extracts and BHT showed similar antioxidant effect on sunflower oil preventing peroxide and conjugated dienes formation. Shelf life of sunflower oil with the addition of V and R extracts and BHT were near 1.4 times higher than the control sample. Virginia and Runner peanut skins had similar antioxidant properties, but Virginia showed higher extraction yield.