Bioactive components of malted millet (Pennisetum glaucum), Soy Residue “okara” and wheat flour and their antioxidant properties

Abstract

ABSTRACT This study evaluated bioactive components and antioxidant properties of malted millet, soy residue “okara” and wheat flour. The flour extracts were screened for phenolic content, flavonoid content and total antioxidant capacity using standard methods. The antioxidant activities of the studied flours to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, reduce iron (111) chloride and inhibit lipid peroxidation and nitric oxide (NO) were determined spectrophotometrically and the effective concentration (IC50) of the extract required to inhibit DPPH, lipid peroxidation and nitric oxide radical formation by 50% was obtained using linear regression analysis. Results indicated that okara flour had a significantly (p < .05) highest flavonoid content following this trend: Okara flour (48.42mg/100g) > malted millet flour (34.73mg/100g) > wheat flour (19.02mg/100g). Malted millet flour showed significantly (p < .05) highest phenol content (38.36mg/100g) >okara flour (26.26mg/100g)> wheat flour (21.17mg/100g). In all these assays studied, the reference antioxidant (ascorbic acid) exhibited lowest IC50 values, while among the flour extracts, wheat flour displayed significantly (p < .05) lowest IC50 value in DPPH and nitric oxide radical assays. The lipid peroxidation assay showed that malted millet exhibited significantly (p < .05) lowest IC50 value (50.19µg/ml) indicating that malted millet demonstrated highest anti-lipid peroxidative functions. The methanolic extract of the studied flours exhibited potent antioxidant activities that increased with increasing amount of extract concentration and this validates their potential use in functional food application.