xanthan gum [zan-thuh n guhm] noun
A polysaccharide derived from the Xanthomonas campestri bacterium, commonly used in food preparation as a thickener, emulsifier, and stabilizer all in one. Many gluten-free products use xanthan gum to improve texture, which is usually provided by gluten-containing ingredients. It is important in these instances that the xanthan gum not be derived from wheat. It can also be made from corn, soy or dairy products; of course those allergic to these foodstuffs should be aware of the source as well. Consuming xanthan gum in large quantities may lead to a laxative effect. Many molecular gastronomists consider it a key additive in their arsenal.
Xanthan gum is a highly effective binder and thickener, and it provides elasticity similar to that of gluten. Most recipes will call for about ½ teaspoon to 1 teaspoon per cup of gluten-free flour, so a little goes a long way; too much can yield a gluey texture. It can be found in many Whole Foods stores.