Xanthan gum is a yellowish-white, free-flowing powder that is soluble in water but practically insoluble in organic solvents. Chemically, it is a high molecular weight polysaccharide used as a rheology modifier. Even in small quantities, it significantly increases the viscosity of liquids. The viscosity of formulations containing xanthan gum remains stable between ambient temperature and 60°C. Additionally, it is suitable for both acidic and alkaline systems, as its viscosity remains nearly constant across a pH range of 2 to 12.
Due to its anionic polysaccharide nature, xanthan gum is compatible with anionic and non-ionic ingredients but is generally incompatible with cationic substances. It is also unstable in the presence of strong oxidizing agents, such as bleach and hydrogen peroxide, which can cause rapid and severe polymer degradation. However, xanthan gum remains stable even in high concentrations (up to 20%) of many mono- and divalent inorganic salts.
Dissolving xanthan gum requires proper dispersion to ensure individual gum particles are fully surrounded by the aqueous medium before hydration. If not adequately dispersed, the outer surface of the particles will hydrate too quickly, forming a gel layer that prevents water penetration, leading to swollen lumps that take additional time and shear to dissolve. High-shear mixing offers quick and lump-free dispersion compared to standard slow mixing procedures. Dissolving xanthan gum in hot water is recommended, as it speeds up the process and produces higher viscosity compared to using room temperature water. This makes it possible to achieve the desired thickness with less material.
An alternative approach is to pre-blend the gum with glycerin before adding it to the aqueous phase. A suggested ratio of xanthan gum to glycerin is 2:5. To prepare, manually mix 2 grams of xanthan gum with 5 grams of glycerin until a smooth, uniform slurry is formed. For glycerin-free formulations, PEG-7 glyceryl cocoate can be used as an alternative. The process closely resembles the method of blending xanthan gum with glycerin, allowing for the quick and easy preparation of even highly viscous gum solutions. Adding the xanthan gum slurry to water is the preferred method, rather than pouring water into the slurry.
