Effect of different processing methods on certain antinutritional factors and protein digestibility in green and white faba bean (Vicia fabaL.)

Effects of several physical treatments (soaking, dehulling, ordinary cooking, microwave cooking, and autoclaving) on the level of antinutrtional factors and in vitro protein digestibility (IVPD) of green and white faba beans were investigated. The raw green and white faba bean seeds were found to contain phytic acid (PA), tannins, trypsin inhibitor activity (TIA), and lectin activity, but α-amylase inhibitor was absent. Dehulling significantly increased the levels of PA, TIA, decreased the level of tannins, but lectin activity was not changed. Cooking methods differently affected the levels of the antinutrtional factors. Thus, PA increased but tannins were not changed; on the other hand, TI and lectin activities were inactivated; ordinary cooking and autoclaving were the most effective in both seeds. For combination effect, soaking following cooking treatments significantly decreased PA, tannins, and lectin activity but increased TIA in both seeds. Moreover, dehulling following soaking and cooking methods resulted in a significant increase of PA and TIA. In vitro protein digestibility of raw green and white faba bean seeds were 72.65 and 73.28%, respectively, and it was improved by all processing methods; soaking-dehulling after autoclaving was the most effective in both seeds. Although some treatments increased the level of antinutrtional factors, they improved IVPD. Therefore, the studied antinutrients are not the only responsible factor for lowering IVPD.