From Study Force Dictionary
Xanthan gum is a thickening agent produced by fermentation, it is used in molecular gastronomy to thicken sauces and dressings as well as to make fat-reduced, no-ice cream milkshakes that are just as thick.
Xanthan gum is a natural thickener derived from fermentation of glucose or sucrose by a bacterium, the Xanthomonas campestris. This very common bacterium is also responsible for frequent outbreaks of dark spots on the leaves of many vegetables, but it is harmless to humans.
Xanthan gum was discovered by the research team of Allene Rosalind Jeanes of the United States Department of Agriculture and has been marketed since the early 1960s.
The main property of xanthan gum is its ability to significantly increase the viscosity of a liquid. This effect is noticeable at concentrations of xanthan gum as low as 1%. The viscosity of xanthan gum solutions is variable. Indeed, it decreases during mixing and returns to its original balance when the product is put back to rest: this property is called "pseudo plasticity”. Xanthan gum is mainly used for its properties as a thickener and stabilizer, although it can also act as an anti-settling agent.
It dissolves easily in all liquids, hot or cold, and is stable under a wide range of temperatures and pH levels. Once heated, xanthan gum loses texture.
Combined with other types of natural gums, xanthan gum can be used to form gels that are resistant to acidic ingredients, whereas traditional gels like pectin and gelatine are not.