Polyphenolics extracts from legume seeds: Correlations between total antioxidant activity, total phenolics content, tannins content and astringency

Extracts of polyphenolic compounds were obtained from seeds of faba bean, broad bean, adzuki bean, red bean, pea, red lentil and green lentil using 80% (v/v) acetone. The total antioxidant activity (TAA) of extracts was determined and their astringency (Sensation Astringency Indices - SAI) investigated using the sensory scaling method. The content of tannins in extracts was expressed as absorbance values at 500 and 550 nm after color developed with vanillin/HCl reagent and after n-butanol-HCl hydrolysis, respectively. A statistically significant correlation was found between the TAA values and total phenolics (P = 0.01), TAA and tannins determined by vanillin method (P = 0.05), TAA and tannins determined after n-butanol-HCl hydrolysis (P = 0.05), SAI values and tannins determined with vanillin method (P = 0.10), SAI values and tannins determined after n-butanol-HCl hydrolysis (P = 0.05), SAI values and total phenolics (P = 0.01), total phenolics and tannin content determined by vanillin method (P = 0.01), total phenolics and tannin content determined after n-butanol-HCl hydrolysis (P = 0.05), tannins determined with vanillin method and tannins determined after n-butanol hydrolysis (P = 0.02).