PURIFICATION AND COMPOSITION OF A POLYURONIDE HEMICELLULOSE ISOLATED FROM WHEAT STRAW

Abstract

A homogeneous polyuronide hemicellulose has been prepared from a crude hemicellulose isolated from wheat straw holocellulose by hot water. The method of preparation consisted of fractional precipitation of the acetylated hemicellulose from chloroform solution by petroleum ether. Approximately 50% of the recovered fractions consisted of a polysaccharide made up of 28 moles of D-xylose, 5 moles of L-arabinose, and 3 moles of uronic acid and having an [Formula: see text] and a molar ratio, methoxyl: uronic anhydride, of approximately 1.0. Intrinsic viscosity measurements indicated a degree of polymerization of approximately 30. Separation of hexosans present in the original hemicellulose showed that they were not chemically combined with the main pentosan fraction. They were recovered admixed with short chain pentosan material containing a higher proportion of arabinose to xylose than the main homogeneous fraction.