Comprehensive structural analysis of a set of various branched glucans by standard methylation analysis, 1 H NMR spectroscopy, ESI-mass spectrometry, and capillary electrophoresis.

Various (semi)-synthetic non-digestible glucans (NDG) (resistant (malto)dextrin, isomaltooligosaccharide, soluble corn fiber, polydextrose) were analyzed by methylation analysis, 1H NMR spectroscopy, ESI-MSn, TLC, and capillary electrophoresis (CE/UV). Partly complementary and partly corroborative results were obtained by these methods yielding a comprehensive overview about the various degrees of complexity and special structural features. Methylation analysis enabled the most detailed quantitative evaluation of glycosidic linkage positions and branching pattern, and detection of furanosyl residues. 1H NMR spectroscopy provided additional information on anomeric configuration. By ESI-IT-MS up to DP 13, for doubly charged up to DP 22 was detected. Glucitol residues in polydextrose as well as anhydrosugar formation in thermally treated glucans could also be recognized from the mass spectra. Furthermore, MS2 of the disaccharide portion gave insights into the linkage positions present in the glucan mixture. Electrophoresis of ANTS-labeled oligosaccharides showed the DP-resolved differences of complexity and was the most powerful method to identify the type of glucan by its CE-fingerprint. The aim was to present complementary analytical data obtained by application of identical conditions and methods to a wide range of NDG with increasing complexity to allow direct structure comparison.