Associative phenomena in galactomannan-deacetylated xanthan systems

The interaction between mesquite seed galactomannan (MSG; D-mannose to D-ga lactose ratio (M/G) similar to 1.1) and deacetylated xanthan (DX) in 5 mM N aCl leading to synergistic gel formation at 25 degreesC was investigated an d compared with the far more studied system made of xanthan and locust bean gum (LBG: M/G similar to 3.5). Rheology and differential scanning calorime try were used to measure temperatures of gel formation and transition entha lpy as a function of polymer composition, while circular dichroism was used to probe the conformation of DX in the LBG-DX system. MSG and DX associate at 25 degreesC with a well defined stoichiometry of 0.6:1.0 (w/w) at low i onic strength Favouring the disordered coil state of DX. When LBG was used in place of MSG in water or 5 mM NaCl. two types of mechanisms of interpoly meric association are envisaged. (C) 2001 Published by Elsevier Science B.V .