Free Radical Scavenging Activity of Some Legumes Hulls Extract and Its Efficacy on Oil Oxidative Stability.

Abstract

Synthetic antioxidants have toxigenic effects, there is therefore growing interest in substituting them with natural antioxidants. Attention is being focused on extracting them from agricultural industry residuals to minimize costs. Legume seed hulls could be cheap sources of such natural antioxidants. This study aims to unravel potential free radical scavenging activity, antioxidant activity, and total phenolic and flavonoid contents of some legumes' hulls extracted by different solvents and evaluate their efficacy to enhance sunflower oil stability. Legume hulls extracted by different solvents were evaluated for their antioxidant activity coefficient (AAC), free radical scavenging activity [by 2,2-diphenyl-1- picrylhydrazyl (DPPH)], and phenolic and flavonoids contents. The protection factor and induction periods (rancimat test) of the highest activity extracts were evaluated. Sunflower seed hull ethyl acetate extract, lupine seed hull ethanol extract, and mung bean hull petroleum ether extract exhibited stronger DPPH scavenging activity, AAC, and protection factor values than other solvents. Ethyl acetate extracts of sunflower seed hulls showed an antioxidant and scavenging activity close (P>0.05) to that detected for α-tocopherol. Legume hulls may possess strong free radical scavenging and antioxidant activity. The analogous effect between sunflower hull extract and α-tocopherol make it a potential, cheaper substitute of α-tocopherol in food systems. The analogous effect between sunflower hull extract and α-tocopherol give it the potency to allow substitution at a concentration of 0.5% of sunflower hull ethyl acetate or 1% of lupine hull ethanol extract instead of 0.5% α-tocopherol to enhance induction periods and protection factors of sunflower oil.