Extraction and characterisation of hemicelluloses from maize stem

Abstract

Extraction and characterisation of hemicelluloses are very important for converting them into functional materials and chemicals. To develop a method for isolation of hemicelluloses from all cell walls. 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. Hemicelluloses with high yieldd were isolated from all cell walls, and contained arabinoxylan as the major polysaccharide. H(3) was substituted by α-L-arabinofuranose, α-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. This modified method is successful for the isolation of hemicelluloses with high yields from all cell walls of maize stem.