Structural features and properties of soluble products derived from Eucalyptus globulus hemicelluloses

► Substituted xylooligosaccharides (XOS) are produced from Eucalyptus wood hemicelluloses. ► Crude liquors containing XOS are refined by physicochemical methods to yield a high purity product. ► The structure of the major compounds present in refined concentrates is assessed. ► The prebiotic protential of the final product is confirmed by in vitro fermentation experiments. Eucalyptus globulus wood samples were subjected to double hydrothermal processing to remove extractives in the first stage, and to cause the selective solubilisation of 4- O-methylglucuronoxylan in the second stage. The hemicellulose-derived products present in the liquors from the second hydrothermal stage (substituted xylooligosaccharides, denoted XOS) were refined by treatments with membranes and ion exchange. The purified XOS product was assayed for composition and characterised by HPLC-RI, HPAEC-PAD, HPSEC, MALDI-TOF-MS and NMR techniques. The results suggested the presence of neutral and acidic XOS with a degree of acetylation of about 0.6. The fermentability of the refined XOS product by faecal inocula was assessed by measuring both substrate consumption and formation of short-chain fatty acids.