Effect of Extraction Techniques and Solvent Systems on the Extraction of Antioxidant Components from Peanut (Arachis hypogaea L.) Hulls

This research work was carried out to investigate the effect of different extraction techniques on antioxidant potential of peanut (Arachis hypogaea) hulls. The antioxidant extracts of peanut hulls (PH) were prepared using different extraction methods such as soaking, stirring, shaking, and sonicated-assisted stirring with methanol/water (80:20) and ethanol/water (80:20) solvents systems. The antioxidant potential of extracts was measured using different in vitro antioxidant assays like estimation of total phenolic contents (TPC), estimation of total flavonoids contents (TFC), DPPH-scavenging capacity, percentage inhibition of linoleic acid peroxidations, and bleachability of ß-carotene in linoleic acid system. TPC and TFC of different PH extracts were found in range of 1.23–8.43 mg/g of dry plant material, measured as gallic acid equivalent, 0.33–5.06 mg/g of dry plant material, measured as catechin equivelent (CE), respectively. All the PH extracts exhibited good free radical scavenging potential and moderate inhibition of linoleic acid peroxidation. Significant (p ≤ 0.05) variations were observed in the antioxidant potentials of various extraction methods and solvent systems. Among all the extraction methods, sonicated-assisted stirring showed better yield and antioxidant capacity. In view of the present findings, it is reasonable to say that different extracts of peanut hulls exhibited varying degree of antioxidant activity, which might be attributed to various mechanisms involved in extraction procedures.