Structural analysis of water-soluble and -insoluble β-glucans of whole-grain oats and barley

Water-soluble and water-insoluble (1→3),(1→4)-β-d-glucans were isolated from whole-grain oats and barley and digested with lichenase. The oligosaccharides thus produced were analysed using anion-exchange chromatography with pulse-amperometric detection (HPAEC-PAD). The FT-IR, 1H NMR and solid-state 13C CP-MAS NMR spectra of the β-glucans were also measured. Analyses of the ratio of oligosaccharides with degrees of polymerisation 3 and 4 (DP3:DP4) showed small structural differences between oats and barley and between the water-soluble and water-insoluble β-glucans. The molar masses analysed using the SEC-HPLC method were 500,000 g/mol for the soluble β-glucans of both oats and barley and <200,000 g/mol for the insoluble β-glucans. No differences were found in the FT-IR and NMR spectra.