Development of an ion-exchange chromatography method for monitoring the degradation of prebiotic arabinoxylan-oligosaccharides in a complex fermentation medium.

Arabinoxylan-oligosaccharides (AXOS) are a new class of prebiotics with promising health-promoting characteristics. However, the mechanism by which bacteria break down these compounds in the colon is still uncharacterized, due to their structural complexity. A new analytical method that offers structural information was developed to characterize AXOS degradation during fermentation. The method was based on the simultaneous determination of arabinose, xylose, xylo-oligosaccharides (XOS), and AXOS by applying high-performance anion-exchange chromatography with pulsed amperometric detection. To study the structural features of AXOS in solution without the use of spectroscopic techniques or standards, enzymatic-based reference degradation chromatograms were generated based on enzymes with known specificity. The new method for fingerprinting showed to be a powerful and fast tool to study AXOS degradation with high repeatability with respect to peak area, peak width at half height, and retention time (respective relative standard deviations of ≤3.1%, 2.8%, and 0.8%). This method was successfully applied to study the degradation kinetics of AXOS in a complex fermentation medium by Bifidobacterium longum LMG 11047. The results showed that this strain could use both the arabinose side chains and xylose backbones up to xylotetraose. The characterization of the degradation abilities of AXOS by colon bacteria will allow a better understanding of the beneficial effects of these prebiotics. Furthermore, if the appropriate enzymes are available to design the reference degradation chromatograms, this new method for the qualitative fingerprinting of AXOS breakdown can also be applied for the breakdown of other complex oligosaccharides and polysaccharides.