Extraction and characterisation of hemicelluloses from maize stem.

Introduction - Extraction and characterisation of hemicelluloses are very important for converting them into functional materials and chemicals. Objective - To develop a method for isolation of hemicelluloses from all cell walls. Methodology - Sequential steps using 90% dioxane, 80% acidic dioxane, 100% dimethyl sulphoxide and 8% NaOH were used for extraction of the hemicellulosic preparations (H(1), H(2), H(3) and H(4)) from maize stem. Advanced NMR techniques were used for the analysis of native hemicelluloses. Results - Hemicelluloses with high yieldd were isolated from all cell walls, and contained arabinoxylan as the major polysaccharide. H(3) was substituted by alpha-L-arabinofuranose, alpha-D-xylopyranose, and acetyl groups (degree of saturation = 0.12/0.09) at O-3/O-2 of xylan. H(4) had a long continuous side chain of arabinose residues, and associated closely with non-cellulosic glucose. The hemicelluloses formed more linkages with guaiacyl lignins, and some p-coumaric acids built a bridge between hemicelluloses and lignin in maize stem. Conclusion - This modified method is successful for the isolation of hemicelluloses with high yields from all cell walls of maize stem. Copyright (C) 2010 John Wiley & Sons, Ltd.