Effects of dehulling and boiling on protein digestibility in faba beans with high and low trypsin inhibitor activity

Abstract

This study investigated how dehulling and boiling affect the in vitro protein digestibility (IVPD) of faba beans with either high (Fuego) or low (Granit) trypsin inhibitor activity (TIA), using the INFOGEST protocol. The results showed that dehulling and boiling affected the TIA and IVPD differently. In cultivar Fuego, dehulling significantly increased the IVPD by 15%, as well as a distinct decrease in TIA by 32%. However, in cultivar Granit, the effect of dehulling on TIA and protein digestibility had no significant effect. Boiling was found to decrease TIA in both cultivars distinctly (with a reduction of 93–96%) and significantly improved the IVPD in cultivar Fuego by 8%, but decreased in cultivar Granit by 13%. In both cultivars, protein hydrolysis during the intestinal phase was most significant, accounting for 58–84% of the total hydrolysis. The boiled faba beans displayed significantly higher levels of hydrolysis compared to raw faba beans during the intestinal phase. The findings suggest that the TIA in different cultivars of faba beans significantly differ and processing results in varied effects on their TIA and digestibility. Beyond the reduction of TIA, thermal treatments can induce comprehensive structural modifications and matrix interactions that affect faba bean protein digestibility differently. Generally, dehulling of faba beans also potentially enhances nutrient availability in faba beans.