Changes in levels of enzyme inhibitors during soaking and cooking for pulses available in Canada

The effects of processing (soaking and cooking) on enzyme inhibitors (alpha-amylase, trypsin and chymotrypsin inhibitors) in a range of pulses (4 peas, 9 lentils, 3 chickpeas, 2 faba beans and 4 beans) were investigated, using soybean as a control. Analysis of variance indicated that pulse type, treatment and their interaction had significant effects on levels of all enzyme inhibitors. Soybean contained the highest levels of trypsin inhibitory activity (TIA) and chymotrypsin inhibitory activity (CIA) among all seeds. alpha-Amylase inhibitory activity was absent from peas, lentils, chickpeas and faba beans, but was present in beans and soybean. TIA was found to be low in peas but high in beans. Beans contained relatively high CIA levels followed by chickpeas, lentils, peas and faba beans. Soaking markedly decreased the activity of enzyme inhibitors. Cooking of presoaked seeds was even more effective as greater reductions (78.7-100%) were observed for all pulses. The content of enzyme inhibitors in pulses varied widely, but levels of protease inhibitors were generally lower that those found in soybean. Processing, in particular heat treatments, drastically reduced these levels.