Compositional differences in some limabean (Phaseolus lunatus) varieties

Eighteen varieties of limabean (Phaseolus lunatus) were analysed for their proximate chemical composition, mineral constituents and amino acid composition. The crude protein levels were remarkably similar except for that of TPL 071-33 (25·9%), which was higher than for most of the other varieties. Ether extract was low in all varieties, with a percentage coefficient of variation of 46·2%. Potassium was the most abundant mineral element, ranging from 550 mg/100 g in TPL 4 to 2380 mg/100 g in TPL 14e. Phosphorus and magnesium contents were also appreciably high in all varieties while calcium was the poorest major mineral element. Methionine and cystine were the most limiting amino acids and showed some degree of intervarietal differences, their coefficients of variation (CV) being 19·0 and 12·2%, respectively. Other amino acids which showed varietal differences included serine (CV 18·2%), glutamic acid (CV 15·4%), proline (CV 14·4%), glycine (CV 14·5%) and alanine (CV 14·4%). Limabean TPL 2 was deficient in histidine whilst trytophan was adequate in all varieties but deficient in TPL 2, TPL 6, TPL 13 and TPL 187. Glutamic acid, followed by aspartic acid, levels were generally the highest in each of the limabean varieties. The implications of these findings are fully discussed.