Isolation and Structural Exploration of Hemicelluloses from the Largest Bamboo Species: Dendrocalamus sinicus

Abstract

Dendrocalamus sinicus, which is the largest bamboo species in the world, has broad prospects for use in biomass-energy and biorefinery applications. In this study, five soluble hemicelluloses fractions were sequentially isolated with 80% ethanol (containing 0.025 M HCl or 0.5% NaOH), and alkaline aqueous solutions (containing 2.0, 5.0, or 8.0% NaOH) at 75 °C for 4 h from dewaxed D. sinicus, and their structural properties were examined. Gel permeation chromatography analysis revealed that the hemicelluloses isolated from D. sinicus had a wide distribution of molecular weights. The hemicelluloses isolated by ethanol had lower weight-average molecular weights (ranging from 17380 to 19620 g/mol), while the hemicelluloses isolated using alkaline aqueous solutions had higher weight-average molecular weights (ranging from 22510 to 42150 g/mol). Neutral sugar analysis indicated that the soluble hemicelluloses were mainly composed of arabinoglucuronoxylans, followed by minor amount of starch. Spectroscopic analyses suggested that the isolated arabinoglucuronoxylans from bamboo (D. sinicus) could be defined as a linear (1→4)-β-linked-xylopyranosyl backbone to which α-L-arabinofuranose and/or 4-O-methyl-glucuronic acid units were attached as single-unit side chains via α-(1→3) and/or α-(1→2) linkages.