The effect of in situ produced dextran on flavour and texture perception of wholegrain sorghum bread

This study evaluated the effects of dextran produced in situ by Weissella confusa A16 on the flavour and texture perception of wholegrain sorghum bread containing 50% of wheat flour. Descriptive sensory profiling revealed that sorghum sourdough bread containing in situ produced dextran (0.56% bread weight) was more elastic, foldable, moist, cohesive, soft, flexible, and smooth compared to control sorghum sourdough or native sorghum breads (p < 0.05), consistently with the instrumental data. Fermentation significantly increased off-notes such as sour flavour, bitter taste, and aftertaste probably due to the acids production and release of small molecular weight polyphenol compounds (e.g. caffeic acid). The dextran-enriched sorghum sourdough bread, however, showed a significant reduction of flavour intensity perception compared to the control sorghum sourdough bread, despite similar levels of acidification and polyphenols. A trained sensory panel (n = 17) was employed to study specifically the masking effect of dextran on sour and bitter notes in model bread systems containing fixed amounts of tastants (acids or caffeine) and varying concentrations of dextran (0.12-0.96% bread weight) above and below the experimentally determined critical overlap concentration C* of dextran (0.43%, w/w). Breads containing higher levels of dextran exhibited a more cohesive, springy, and soft texture with significantly less perceived sourness and bitterness intensity. The flavour suppressing seemed to occur at above the critical overlap concentration but remained unaffected at lower concentrations. Dextran produced by W. confusa A16 is a promising texture-enhancing and flavour-masking agent in wholegrain products, which may lead to future innovations in this area.