Nutritional potential of nine underexploited legumes in Southwest Nigeria.
There is increasing interest in finding new food sources to alleviate malnutrition in developing countries. Nine little known legumes (Mallotus subulatus (white variety), Cassia hirsutta, Canavalia ensiformis, Vignea subterranean (checkered variety), Vigna racemosa, Mallotus subulatus (red variety), Vignea subterranean (cream variety), Sphenostylis sterocarpa and Cajanus cajan in the South western Nigeria were studied to highlight their nutritional significance. The proximate composition, fatty acid composition, total phenolic content, antioxidant activity and amino acid profile of the legumes were evaluated using standard methods in the literature. Significant (p<0.05) variations existed among the legumes with respect to their proximate composition, fatty acid profile, total phenolic content, antioxidant activity and amino acid composition. Mallotus subulatus (red variety) rated highest in protein, Vigna racemosa and Sphenostylis sterocarpa had high starch contents, while Cajanus cajan rated best in dietary fibre (non starch polysaccharides) among the legumes tested. The total unsaturated fatty acids were much higher than the total saturated fatty acids in all the legumes. Linoleic acid (C18:2) was the most abundant polyunsaturated fatty acid (PUFA) identified, at varying levels, in all the legumes studied. All the legumes had varying levels of linolenic acid (C18:3). Sphenostylis sterocarpa had the least essential fatty acid contents (32.73%) and the highest (57.25%) was found in Cassia hirsutta. Cajanus cajan had the highest total phenolic content (293.23 mg/100g) and also rated best in its antioxidant activity. The percentage total essential amino acids were between 45.53 and 48.44 which are considered adequate for ideal protein foods. All the legumes were good sources of total phenolics and possess moderate to high antioxidant activities suggesting that these lesser known legumes are promising commodities in combating food and nutrition insecurity in Nigeria and other countries where they are known and consumed.