Xanthan gum

The polysaccharide dissolves readily in both hot and cold water, to form a viscous, non-thixotrophic solution, which usually show some opalescence. Concentrations of 0,1-1,0% have a pH in the range of 6.0-7.0. At concentrations as low as 0.25%, solutions will show weak gelation at room temperature. In the cold, the set to soft reversible gels, especially in the presence of salt or alcohol [1]. Removal of the terminal mannose (atet) will lower the viscosity and removal of the terminal mannose and deacetylation (natet) of the remaining mannose will increase viscosity [3].

Temperature has little effect on the viscosity of the polysaccharide, even in the presence of salts. When heat is applied, potassium chloride stabilizes the polymer, and increase the viscosity. The viscosity is essentially independent of pH, and the dry polymer can be dissolved directly in most acid solutions. The viscosity is a function of the concentration of polysaccharide, pH and the composition of the salt. The increased viscosity is believed to be from cross-linking [1]. Heating and cooling xanthan causes the molecule to be more rigid, this is believed to be from the transition from a single to a double helix [4].

No specific adhesion to cellulose has been observed [8].

Xanthan does not adhere signicantly (<5%) to curdlan [9].

The galactomannan locust bean gum forms gels with xanthan gum [10].

The polymer is readily deacetylated by diluted alkali at room temperature. Dilute alkali will not remove the pyruvic acid.

Tensile adhesive strenght on mucin vs. time (s ± s.d. (j/m³) at time (min)) for polymer film:
8 min: 1.7±0.4
15 min: 1.9±0.4
20 min: 2.0±0.4
25 min: 2.1±0.5 [2]

Contact angle for water on polymer film (θ_w ± s.d.): 88.5°±4.8° [2]