3. Physico-chemical properties

The main physico-chemical properties of xanthan gum are linked to interactions between macromolecules and water. The first step is to dissolve the polysaccharide.

• Solubility

Xanthan gum is soluble in cold water (from 10 to 20 ˚C). Solubilization takes place in two stages. The first stage is the dispersion of the grains making up the powder, i.e. the individualization of the particles. The larger the grain size, the faster the dispersion. The second stage is hydration. Water molecules gradually attach themselves to the macromolecules, reducing solute-solute interactions until the macromolecules become individualized. Gums feature hydroxyl groups and negative charges that facilitate solute-water interaction. In addition, the branches spread the main chains apart, facilitating hydration. Hydration is considered...