Investigations of antinutritional factors of the winged bean (Psophocarpus tetragonolobus)

Abstract Twelve varieties of winged bean ( Psophocarpus tetragonolobus ) were analyzed for tannin, phytic acid, trypsin inhibitor, chymotrypsin inhibitor, α-amylase inhibitor and lectin. Tannin contents ranged from 1·35–6·75 mg/g of bean. Phytic acid contents ranged from 7·77–12·03 mg/g of bean and phytate-phosphorus represented a considerable percentage of the total phosphorus (44·3–54·8%). Chymotrypsin inhibitory activities were about twofold higher than trypsin inhibitory activities. α-amylase inhibitory activities could not be detected in any of the winged bean varieties used in this study. Hemagglutinating activities were observed with respect to all types of trypsinized human erythrocytes (A, B and O). However these activities disappeared completely after heating in a boiling water bath for 10 min.