Phenolic Compound, Antioxidant Activity and Nutritional Components of Five Legume Seed

Abstract

Legume is a major source of antioxidant and nutritional component that is very helpful for human health. In recent years, the functional properties of legume seed have received attention, particularly with respect to antioxidant, antitumor, anti-diabetic and anti-cholesterol effects. The objective of this study was to investigate the phenolic compound, flavonoid, antioxidant capacity and nutritional profiles of five legume seeds. The phenolic content determined according to the Folin Ciocalteu method, for five legume samples varied from 13.68 to 35.5 mg Tannic acid equivalent/g of extract. Flavonoid content was measured using 2% aluminum chloride varied from 1.21 to 4.81 mg quercetin equivalent/g of extract. Red bean contained maximum phenolic (35.5 mg/g extract) and flavonoid (4.81 mg/g extract) content that was statistically different from other legume seed (p<0.05). Antioxidant activities were comparatively assessed by ABTS (2, 2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical decolorization assay method. Red bean, soybean and black bean showed good free radical scavenging capacity by ABTS and DPPH. Red bean contained highest amount of protein (262.73 ± 8.87 mg/g), free amino acid content (27.19 ± 0.40 mg/g) and reducing sugars (35.78 ± 0.76 mg/g) whereas black bean contained highest amount of total soluble sugar content (570.52 ± 5.44 mg/g). Obtained results suggest that red bean, soybean and black bean can be regarded as promising candidates for natural plant sources of antioxidants with high nutritional value.