Molecular architectures and functional properties of gellan gum and related polysaccharides

Certain linear and branched polysaccharides produced by unrelated species of bacteria are grouped in the gellan gum family because of their conserved backbone structures. All have excellent rheological properties and, thus, are useful in industrial applications. Physicochemical investigations of these polysaccharides in solution and structural studies of them in the solid state using X-ray diffraction have provided mutually complementary results. The study double-helix morphology that is characteristic of gellan gum prevails in other members of the gum family in spite of the presence of substituents and side chains. Association between double helices is facilitated by ions and water molecules. The observed physical properties of solutions and gels made with members of the gellan gum family can be directly rationalized at the molecular level in terms of the interactions taking place between the polymer helices.