Nutritional and health promoting bioactive properties of Canadian faba bean in comparison to pea and soy

With the current environmental, public health and food security challenges, there is an increasing need for new high quality and more sustainable protein sources. Faba bean is an underutilized pulse with many favourable characteristics, including a high protein content (28-32%). This study aimed to assess the nutritional quality and health-promoting bioactivities of faba bean proteins after in vitro gastrointestinal digestion. Three Canadian faba bean varieties (Fabelle, Malik and Snowbird) were compared to two control legumes (pea and soy). Raw and processed legume flours (dehulled and boiled) were digested using an in vitro standardized gastrointestinal INFOGEST digestion protocol, to which a digestion phase was added to mimic brush border digestion. The in vitro Digestible Indispensable Amino Acid Scores (IV-DIAAS) were calculated based on amino acid quantification in the digestates. The IV-DIAAS of raw faba bean varieties ranged from to 43–49%, which were higher than those of pea (33 %) and soy (36%). Although, the determined IV-DIAAS values were low, they strongly correlated with published in vivo data (r=0.879, p=0.009). Boiling at the used conditions resulted in an increased protein aggregation leading to lower protein digestibility. For the evaluation of faba bean potential health promoting properties, the digestates of all studied faba bean varieties, pea and soy were filtered on a 3 kDa molecular weight cut-off membrane and recovered peptides in the permeate were assessed for their antioxidant, antidiabetic and antihypertensive activities using in vitro and cellular assays. Overall, faba bean had better antioxidant, antihypertensive (Angiotensin-converting enzyme inhibition) and antidiabetic activity (Dipeptidyl-peptidase-IV inhibition) properties than pea but lower than soy. In summary, this study indicates that faba bean proteins are nutritionally comparable to pea and soy along with valuable bioactive potential against non-communicable diseases. It also demonstrates the utility of the modified INGOGEST digestion for the assessment of protein quality.