Structural features and feruloylation modulate the fermentability and evolution of antioxidant properties of arabinoxylanoligosaccharides during in vitro fermentation by human gut derived microbiota

In this study, the impact of structural features of (feruloylated) arabinoxylanoligosaccharides (AXOS) on their fermentability and antioxidant properties during in vitro fermentation was investigated. Two AXOS samples with a low average degree of arabinose substitution, specifically differing in average degree of polymerization, and three AXOS samples, specifically differing in ferulic acid (FA) content and appearance (free or bound), were incubated with cultured human colon microbiota. While the impact of average degree of polymerization on AXOS fermentation was small under the conditions used, both bound and free FA inhibited AXOS fermentation. Bound FA probably hinders enzyme activity sterically. Free FA and its microbial metabolites can exert antibacterial effects. Feruloylated AXOS samples exhibited good antioxidant properties, although the antioxidant activity decreased during fermentation as free or released FA was further metabolized.