Xanthan (Xanthan Gum)
The anionic xanthan is a fermentation product and is created by natural microorganisms (Xanthomonas campestris, hence the name) on the basis of glucose or sucrose-containing substrates. After fermentation, which can last up to 2 days, the fermentation batch is pasteurized, the xanthan is precipitated with isopropanol, filtered or centrifuged, dried and ground. It belongs to the long-chain, anionic polysaccharides; Its components include D-glucose, mannose and D-glucuronic acid in a ratio of about 3:3:2.
We buy xanthan as a whitish powder with a faint, characteristic odor.
Effect and cosmetic use
In practice, xanthan has proven itself as a gelling agent and stabilizer for hot and cold-stirred emulsions in combination with other emulsifiers, in deodorants, hydro and hydro-dispersion gels and as a skin-friendly thickener in cosmetics, shampoos, shower gels, etc. In addition to its emulsion-stabilizing properties, xanthan has, like all of them Consistency enhancers built up with sugar-like structures. a moisture-binding effect and reduces transepidermal water loss through its film-forming properties; in cold, dry weather we therefore recommend a combination of moisture-binding substances with xanthan or comparable polysaccharides (e.g. hyaluronic acid ).
In contrast to classic emulsifiers, irritating effects from cosmetically used xanthan are excluded due to the high molecular weight, since it does not penetrate the horny layer.
processing
Xanthan is readily soluble in both cold and warm water and exhibits high freeze, thaw and temperature stability. It is also alcohol and salt compatible and pH tolerant. The anionic xanthan is excellently suited to create stable surfactant emulsions (both with nonionic and with anionic surfactants) with a high water content.
Emulsions thickened with xanthan gum are stable at rest and become more fluid with agitation and high shear (you know that from tomato ketchup; it also becomes more fluid when shaken), emulsions with this flow behavior are called thixotropic. They are generally found to be very pleasant to apply, because the products can be distributed very easily and smoothly by the shearing forces that arise when they are spread on the skin. In a direct comparison, a 1% gel with xanthan gum is slightly more viscous than a 1% gel with natrosol, but has a different flow behavior: while the natrosol gel
can be poured like a liquid, the xanthan gel (including the transparent gel produced with xanthan) shows the gel character more clearly with a slightly inhomogeneous flow.
The use concentration is 1%