Abstract Nutraceutical foods are thought to play an important role in the prevention and management of cardiovascular diseases, diabetes, obesity and some cancers. This study was undertaken to screen the commonly grown Zambian market classes of common beans for nutraceutical value based on the antioxidant activities (DPPH and FRAP) and total polyphenolic profiles. Phenolic phytochemical profiles were determined using Folin Ciocalteu assay and aluminium chloride colorimetric method. The total polyphenol content ranged from 37.3 to 123.7 mg GAE / 100 g DW. Red beans consistently displayed the highest total polyphenol contents in both the methanolic and aqueous extracts, followed by grey mottled, brown and white. Tannin concentration ranged from 10.2 to 55.4 mg GAE / 100 g DW for the aqueous and from 3.1 to 53 mg GAE / 100 g DW for the 70% methanol extract. Flavonoid concentration ranged from 42.1 to 62.6 mg quercetin equivalents / 100 g DW (aqueous extraction) and 95.2 to 123.5 mg quercetin equivalents / 100 g DW (70% methanol extraction). The various classes of common beans displayed varying antioxidant activities. The bean extracts exhibited DPPH free radical scavenging activities with pseudo firstorder rate constants (K) ranging between 0.006 min -1 and 0.053 min -1 and FRAP derived antioxidant power between 1.69 and 6.88 Fe 2+ / 100 g DW. The red market class displayed the highest antioxidant activity in the aqueous extract, but showed little difference with the grey mottled beans in the methanolic extract. Ranking the market classes based on the free radical scavenging capacities and the FRAP-derived total antioxidant power, the following order was observed: red beans > grey mottled beans > brown beans > white beans. On a comparative basis, white beans displayed far lower antioxidant activities compared to the others. Keywords: antioxidant, polyphenols, nutraceuticals, common beans Cite This Article
