SOME ASPECTS OF THE BIOCHEMISTRY AND NUTRITIVE-VALUE OF AFRICAN YAMBEAN SEED (SPHENOSTYLIS-STENOCARPA)

The proximate and mineral compositions, amino acid profile and the quality of the protein of three varieties of African yambean (Sphenostylis stenocarpa) seed, in the raw, autoclaved and cooked forms, were assessed. The average crude protein, crude fibre and ash values of the raw yam bean were 23·3%, 4·9% and 3·9%, respectively. Mineral concentrations, on dry weight basis, were: 3·3-4·2 g kg-1 for P; 0·70-0·80 g kg-1 for Ca; 1·3-1·7 g kg-1 for Mg; 9·7-12·0 g kg-1 for K; 0·04-0·06 g kg-1 for Na; 27·8-46·2 mg kg-1 for Mn; 38·2-44·0 mg kg-1 for Zn; 52·0-63·0 mg kg-1 for Fe and 8·1-11·8 mg kg-1 for Cu. The amino acid composition of the protein indicated lysine, 7·38-8·09 g 16 gN; tryptophan, 1·21-1·26 g 16 gN and methionine + cystine, 3·08-3·45 g 16 gN to be above, or close to, the values recommended by FAO/WHO. Cooked yam bean seeds contained relatively lower amounts of the nutrient components determined. Significant differences (P < 0·05) between raw, autoclaved and cooked seeds were found for the protein quality indices. The findings are discussed in terms of the nutritional potential for this resource for man and livestock. © 1990.