Distribution of phenolic compounds in mung bean (Vigna radiata), red bean V(igna angularis), black bean (Vigna cylindrical) and white bean (Vigna unguiculata) and their antioxidant capacity

Abstract

Total phenolics and flavonoids of four kinds of colored beans (black bean, mungbean, red bean and white bean) grown in Vietnam were investigated. The three solvents (ethanol, methanol and acetone) and different ratio of solvent to water were used to determine the best solution for extraction of total phenolics and flavonoids of beans. For extraction of total phenolics, the ratio of methanol to water at 25/75 was the best for black bean whereas the ratio of solvent to water at 0/100 was good for extraction of free phenolic compounds of red bean, mung bean and white bean. Water was also detected as a good solvent for total flavonoid extraction. The total phenolics of the black bean was the highest, followed by red bean, mung bean and white bean, whereas the total flavonoids increased in order of white bean, black bean, mung bean and red bean. As a result, the extracts of colored beans could be used as a functional food or food additive in food and pharmaceutical industries. Keywords: Total phenolics, total flavonoids, colored beans, functional food