Faba bean tempeh: The effects of fermentation and cooking on protein nutritional quality and sensory quality

Faba bean proteins have lower nutritional quality compared to animal proteins, as plant proteins, in some cases, provide a less complete profile of essential amino acids (EAA) and contain antinutritional factors that can limit protein digestibility. Tempeh fermentation though is reported to improve the protein nutritional quality of plant proteins. Therefore, we aimed to investigate the effect of fermentation conditions and cooking on improving protein nutritional quality and sensory quality of faba bean tempeh. Nutritional quality was assessed by in vitro protein digestibility (IVPD), amino acid composition, and trypsin inhibitor activity (TIA). Furthermore, released peptides before and after fermentation were tracked by proteomics. The results showed that a longer fermentation time combined with a higher temperature resulted in a higher overall IVPD and a complete EAA profile. Fermentation alone did not significantly reduce TIA; however, tempeh still exhibited lower TIA levels compared to raw faba beans. Cooking did not significantly affect protein nutritional quality of tempeh. Moreover, different fermentation conditions had no significant impact on the sensory quality of cooked tempehs. In summary, adjusting fermentation conditions can enhance faba bean tempeh's protein quality without compromising taste. This study underscores the potential of faba bean tempeh as a high-quality protein source.