Investigations on the trypsin inhibitor,hemagglutinin, phytic and tannic acid contents of cowpea Vigna unguiculata

Ten cultivated varieties of mature dry beans Vigna unguiculata were analysed for trypsin inhibitor (TI) and hemagglutinating activities, phytic acid, phytic acid-phosphorus and tannic acid. The respective concentrations were: 19·6–28·2 TUI mg^?1 protein,¹ 33·5–98·9 HU mg^?1 protein,² 280–331 mg 100 g^?1, 131–200 mg 100 g^?1 and 0·42–0·78 g 100 g^?1 dry weight. Phytic acid-phosphorus as a percentage of total phosphorus was highest in Farv-13 (49·9) and lowest in Samaru local (29·8). Considerable variability in hemagglutinating activity was evident among the different varieties as indicated by the high percentage co-efficient of variation. Some of these differences may be genetic and may provide an opportunity for the genetic development of cowpea strains with superior protein quality, low in hemagglutinin content.