Antioxidant activities and anthocyanins composition of seed coats from twenty-six kidney bean cultivars

Colour features, anthocyanins composition and antioxidant activities of the coats from 26 kidney bean cultivars were investigated. The colour of kidney bean coats was diverse, and a good correlation was observed between c value and delphinidin content (r2 = 0.7454). Based on 5 common forms of anthocyanidins, 16 anthocyanins were identified. The individual content of pelargonidin, cyanidin, petunidin, delphinidin, malvidin and the total anthocyanindins were in the ranges of 0-0.71, 0-1.44, 0-0.41, 0-4.45, 0-0.27, and 0-5.84 mg/g of dry weight of bean coats. Significant differences of the antioxidant activities were observed. Non-white bean coats which contained more anthocyanidins showed much higher antioxidant activities than the white ones which contained no anthocyanidins. Delphinidin and cyanidin played an important role in the strong antioxidant activities of the tested samples. Our study revealed that appropriate selection of kidney beans could provide abundant sources of anthocyanins for food colourants endowed with antioxidant activities.