SOLUTION CHARACTERISTICS OF THE XYLOGLUCAN EXTRACTED FROM DETARIUM SENEGALENSE GMELIN

The macromolecular solution properties of detarium xyloglucan, a seed extract of the plant Detarium senegalense Gmelin, were investigated by steady and dynamic shear rheometry, and static light scattering. The main polysaccharide of detarium gum is a xyloglucan, consisting of a c ellulosic backbone with single-unit alpha-D-xylopyranosyl substituents attached to carbon-6 of the glucosyl residues, and with some of the x ylose residues further substituted at carbon-2 by beta-D-galactopyrano syl residues. In this paper, all the semi-dilute solution characterisa tion work seems to be very largely consistent with much of the publish ed data for the rheology of other polysaccharide solutions and suggest s that detarium gum is a well behaved linear polymer entanglement netw ork system. It has been established that when C < similar to C eta(sp )proportional to C1.3, while at C > similar to 2C, eta(sp)proportiona l to C-4.0. The static light scattering technique was successfully app lied to examine the molecular weight and architecture of the detarium xyloglucan macromolecule by employing pressure heating treatment of th e samples. The scattering profile for detarium xyloglucan is not consi stent with that of a linear macromolecule, but instead strongly sugges ts a small degree of long chain branching. The implications of this fi nding are discussed. (C) 1997 Elsevier Science Ltd.