Chemical composition, protein fractionation, essential amino acid potential and antimetabolic constituents of an unconventional legume, Gila bean (Entada phaseoloides Merrill) seed kernel

Abstract

AbstractPhysical characteristics of pods and seeds, proximate composition, different protein fractionation, SDS‐PAGE analysis of proteins, amino acid composition, starch content, fatty acid profiles and various antimetabolic substances of Gila bean (Entada phaseoloides Merrill) were studied. The pod length and the number of seeds per pod ranged from 55 to 90 cm and from 5 to 11 respectively. The kernel comprised 66.1% of the seed weight (18.41 ± 1.14 g). The seed kernels contained 256.7 g kg−1 crude protein, 108.1 g kg−1 lipid, 27.3 g kg−1 ash and a high content of carbohydrate (585.7 g kg−1). The levels of potassium, phosphorus, zinc and iron were similar to those in conventional pulses. Among the different protein fractions of seed kernels, albumins constituted the major storage proteins (69.7%). The kernel proteins were rich in essential amino acids, particularly sulphur‐containing amino acids, and their values appeared to be higher than the FAO/WHO (1990) reference protein for a 2–5‐year‐old growing child and soybean, and comparable to hen egg. Seed kernel lipids contained high levels of unsaturated fatty acids, oleic and linoleic acids, which accounted for 83% of the total fatty acid recovered. The kernel exhibited high trypsin and chymotrypsin inhibitor activities (96.65 mg TI g−1 and 30.02 CIU mg−1 sample respectively) in addition to containing phenolics, phytic acid, lectins and oligosaccharides. Another major toxic constituent was identified as a group of triterpenoid saponins (3.21%), which had high haemolytic activity (HeU) against cattle erythrocytes and caused high mortality in fish. The in vitro digestibility of the kernel protein was low (67%).© 2001 Society of Chemical Industry