The Effect of Processing on the Trypsin Inhibitor, Hemagglutinin, Tannic Acid and Phytic Acid Contents of Seeds of Ten Cowpea Varieties

Trypsin inhibitor (TI) and hemagglutinin activities, tannic acid and phytic acid contents were determined in ten varieties of cowpea. The different varieties were subjected to four processes; cooking, soaking, autoclaving and germination. TI and hemagglutinin activities were completely eliminated by cooking and autoclaving, while tannic acid and phytic acid contents were only partly affected. Cooking reduced tannic acid contents by 31.0–47.3%. Soaking for three days decreased TI activity by a mean of 31.2%, hemagglutinin activity by 19.0%, tannic acid by 13.4% and phytic acid by 24.4%. Maximum germination effects on TI and hemagglutinin activities were obtained in ‘Westbreed’ and ‘Kano 1696’ where percentage losses amounted to 57.2 and 57.6, respectively. The phytic acid contents of all varieties were greatly reduced by germination.