Isolation and NMR characterisation of a (4-O-methyl-d-glucurono)-d-xylan from sugar beet pulp

Stable aqueous suspensions of purified and homogenised sugar beet pulp (SBP) cellulose were subjected to various TFA treatments which induced a flocculation of the suspension and the release of a number of polysaccharides. Among these, a 4-O-methyl glucuronoxylan was isolated and characterized by 1H and 13C NMR spectroscopy. In this polysaccharide the molar proportions of d-Xyl and 4-O-Me-d-GlcA were found to be 7:1. The presence of a glucuronoxylan at the surface of the cellulose microfibrils is very likely involved in the stability of the suspensions. To our knowledge, the presence of a 4-O-methyl-glucuronoxylan in the sugar beet cells has not been described previously.