Nutritive value of the winged bean (Psophocarpus palustris Desv.)

Abstract

The winged bean (Psophocarpus palustris Desv.) has been grown successfully for several seasons, on an experimental basis, in the forest belt of Ghana, where earlier attempts to grow the soya bean had proved unsatisfactory. Although botanically different, the composition of the dry seeds was found to be very similar to that of the soya bean, containing 37.3 yo protein, 18.1 Yo fat, 13.9 ppm thiamin and 1.8 ppm riboflavin. The oil of the seeds contained 125.9 mg tocopherol (y+P) per 100 g. The amino acid composition of the protein was very similar to that of the soya bean, with methionine as the first-limiting amino acid. The content of unsaturated fatty acids and that of polyunsaturated essential fatty acids were satisfactory. Active trypsin inhibitor found in the raw seeds could be destroyed satisfactorily by moist heat. No urease activity was detected. The protein efficiency ratio (PER) and net protein utilization (NPU) of the beans determined with rats, were superior to those of groundnuts. The supplementary value of the protein was shown by mixing two parts of the winged bean and three parts of maize flour. When adjusted to either 10 Yo or 16 yo protein, the PER values of these mixtures were similar to those of skim milk. At the 16 % protein level, addition of skim milk or 0.3 yo DL-methionine to this mixture produced only an insignificant improvement in PER value. The pleasant, sweet taste even when in the raw state is one of the advantages of the winged bean. Although, it is a climber, and should be staked, its cultivation on a small scale in selected areas of Ghana is recommended