ABSTRACT
In hardwoods such as aspen, beech, and birch, the hemicellulose consists chiefly of O-acetyl-(4-O-methylglucurono)xylan [11], often simply referred to as xylan (Fig. 2). The backbone consists of h-(1!4)-linked D-xylopyranosyl residues substituted with one a-(1!2)-linked 4-O-methylD-glucuronic acid per approximately every 10th such residue. The xylopyranosyl residues are partially acetylated in the C-2 and/or C-3 positions [11]. The degree of acetylation in native aspen glucuronoxylan has been reported to be between 0.6 and 0.7 [12-13].
