Introducing Capillary Electrophoresis with Laser-Induced Fluorescence Detection (CE-LIF) for the Characterization of Konjac Glucomannan Oligosaccharides and Their in Vitro Fermentation Behavior

The application of capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) as a tool for the characterization of complex carbohydrate structures was investigated for konjac glucomannan (KGM) oligosaccharide mixtures and the monitoring of their structural changes during 72 h of in vitro fermentation with human gut flora. Different types of KGM oligosaccharide mixtures were produced from a KGM polysaccharide using endo-beta-(1,4)-mannanase and endo-beta-(1,4)-glucanase. Distinction of structures emerging from different enzymatic KGM digests and detection of acetylated oligosaccharides were possible by both CE-LIF and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Using CE-LIF it could be shown that the endo-beta-(1,4)-glucanase digest exhibited a large degradability of the DP2, DP3, DP5, and DP6 components during in vitro fermentation, whereas the endo-beta-(1,4)-mannanase digest was digested only slightly, thereby highlighting the influence of structural characteristics on the fermentability by human gut flora.