SOLUTION PROPERTIES OF WATER-INSOLUBLE RYE-BRAN ARABINOXYLAN

An arabinoxylan, extracted from rye bran, was measured by viscosity and lightscattering techniques in different solvents as a function of time over a period of more than three years. The freshly isolated polysaccharide is soluble in DMSO as a double stranded complex. In the course of time, clusters of about seven strands are formed as an intermediate structure which further aggregates unspecifically to very large clusters, which after about three years comprise more than 800 chains. These clusters can be partly broken up with the well-known complexing solvents for cellulose: cuoxam, cadoxen and the iron tartrate alkali complex FeTNa. A substructure of clusters with seven aggregated strands is obtained. DMSO is not capable of disrupting the large clusters and it is a poorer solvent than DMSO containing 10% water. Although used to extract the xylan, 1 N NaOH solution is not a food solvent and clusters of about 30 chains were found. The molecular weight of the individual single-stranded xylan was found from the carbanilate derivative which gave a DPw of 423.