Abstract
The nutritional quality of some improved varieties of chick peas (Cicer arietinum), mash beans (Phaseolus mungo), mung beans (Phaseolus aureus) and cow peas (Vigna sinensis), grown in Pakistan, was measured chemically (including amino acid analyses) and biologically in N‐balance experiments with growing rats. Lysine and total sulphur amino acids were lowered in varieties with a higher content of protein. The true protein digestibility (TD), biological value (BV) and net protein utilisation (NPU) of different varieties of chick peas, mung beans and cow peas varied between 85–89, 83–85 and 87–92%, 62–69, 54–56 and 55–59% and 55–60, 45–48 and 50–51%, respectively. The TD of protein was highest (89%) in chick peas, 6560 having a higher protein content (29.4%) while its BV was lowest (62%) as compared to the other varieties of chick peas. There was a significant correlation (r=0.97) between BV and the total sulphur containing amino acids and BV could be predicted from the regression equation; BV (%)= 33.03 + 10.56x methionine+cystine (g per 16 g N). This indicates that methionine+cystine are the first limiting amino acids in these varieties. Tannin content does not seem to affect the TD of mash and mung beans.