COMPOSITION AND RHEOLOGICAL PROPERTIES OF CASHEW TREE GUM, THE EXUDATE POLYSACCHARIDE FROM ANACARDIUM-OCCIDENTALE L

Anacardium occidentale gum from Brazilian plants has a higher galactose content and lower arabinose and rhamnose content than those gums from India and Papua. The other constituents (glucose, mannose and glucuronic acid) are similarly distributed. GPC of cashew gum detected the presence of 6% polysaccharide-protein complex, 42% polysaccharide of M(pk) 1.6 x 10(4). The whole gum is a low viscosity polysaccharide with an activation energy of flow for solution at 2 and 3% (similar to 16 kJ mol(-1)), characteristic of systems with little intra and intermolecular interactions. Experiments on the effects of NaCl, CaCl2 and AlCl3 on the reduced viscosity, as well as the effect of salt concentration on the specific viscosity, indicated that the affinity between A. occidentale gum and metal ions follows the order: Al-3 > Ca2+ > Na+.