Masking off-flavors of faba bean protein concentrate and extrudate: The role of in situ and in vitro produced dextran

This study produced dextran both in situ by fermentation with Weissella confusa A16 and in vitro by isolated W. confusa A16 dextransucrase enzyme, and investigated its effects on the flavor properties of faba bean protein concentrate (FPC) and the corresponding extrudates prepared by high moisture extrusion. Descriptive sensory profiling revealed that the FPC and extrudates had an intense pea odor and flavor, bitter taste, and astringency. Partial least squares regression analysis suggested that the pea flavor was related to the presence of lipid-oxidation products such as hexanal, heptanal, and nonanal, whereas the bitterness and astringency were likely linked to vicine, convicine, condensed tannins, and arginine. Fermentation under optimized conditions resulted in low acid formation and sufficient dextran production (1.2% end-product basis), which was effective in masking pea and bitter off-notes and enhancing pleasant flavors in FPC (sweet and fruity) and extrudates (sweet and umami). The sweetness was related to fructose produced during fermentation, and the fruity odor was linked to the generated isoamyl isovalerate and ethyl acetate. The masking effect on pea and bitter off-notes was further confirmed by adding enzymatically synthesized dextran in FPC (1.2% dextran) and extrudates (1% dextran). Overall, fermentation with W. confusa A16 or addition of the enzymatically produced dextran showed potential for masking off-flavors of faba bean-based ingredients and extruded meat alternatives. Furthermore, the fermentation method was associated with nutritional benefits (reduction of anti-nutritional factors, e.g., condensed tannins and verbascose) and the generation of flavor compounds/precursors (e.g., esters and free amino acids).