A comparison of the proximate, mineral and amino acid composition of some known and lesser known legumes in Nigeria

Abstract

The proximate, mineral and amino acid composition of various cultivars of three legumes consumed in Nigeria were compared. They include the African Yam bean ( Sphenostylis stenocarpa (Hochst ex. A. Rich) Harms.), Pigeon pea ( Cajanus cajan (L) Millsp.) and Cowpea ( Vigna spp.). Results showed that, on average, apart from protein and ash, the proximate compositions of all the legumes were similar. The protein content of cowpea was significantly higher ( P < 0·01) than those of the African Yam bean and Pigeon pea. Cowpea and Pigeon pea had significantly higher values for ash ( P < 0·05) than the African Yam bean. Two popular cultivars of Vigna unguiculata (white and brown) contained lower values of dietary fibre, i.e. about 60% of the amount in the African Yam bean and 48% of that found in the Pigeon pea. Cowpea seemed to have a better mineral pattern than Pigeon pea and the African Yam bean. In terms of amino acid composition, the African Yam bean had a better pattern of essential amino acids (EAAs). All legumes were, however, deficient in cystine and methionine. In addition to these amino acids, Pigeon pea was also deficient in valine and isoleucine. The necessity of combining legumes with cereals is further stressed.