Size and shape of inulin in dimethyl sulphoxide solution

A comparative hydrodynamic characterization of the solution properties of the fructan polysaccharide inulin extracted from two different sources and solubilized in dimethyl sulphoxide is described. For Jerusalem artichoke inulin a weight average molecular weight M-w of 3400 +/- 150 Da from sedimentation equilibrium in the analytical ultracentrifuge is obtained, together with an intrinsic viscosity [eta] of 9.1 +/- 0.2 ml g(-1) and a sedimentation coefficient (corrected to a solvent density and viscosity of that at water at 20 degrees C) s(20,w) of similar to 0.4 S. Chicory root inulin had somewhat similar properties, with an M-w of 6200 +/- 200 g mol(-1), [eta] of 10.7 +/- 0.2 ml g(-1) and s(20,w) also of similar to 0.7 S. These results appear reasonably consistent with a rather compact model with a relatively large degree of solvent association. (C) 1999 Elsevier Science Ltd. All rights reserved.