Xanthan gum sounds like something out of a science fiction movie, but it actually has quite mundane origins. The term actually comes from a kind of bacteria called Xanthomonas campestris. This bacteria is the culprit behind the icky, black rot that can form around leafy vegetables and cauliflower if they are left too long in the damp vegetable bin of the refrigerator.
Xanthan gum derives its name from the strain of bacteria used during the fermentation process, Xanthomonas campestris. This is the same bacteria responsible for causing black rot to form on broccoli, cauliflower and other leafy vegetables. The bacteria form a slimy substance which acts as a natural stabilizer or thickener. The United States Department of Agriculture ran a number of experiments involving bacteria and various sugars to develop a new thickening agent similar to corn starch or guar gum. When Xanthomonas campestris was combined with corn sugar, the result was a colorless slime called xanthan gum.
Xanthan gum is considered a polysaccharide in scientific circles, because it is a long chain of three different forms of sugar. What's important to know is that all three of these natural sugars are present in corn sugar, a derivative of the more familiar corn syrup. The Xanthomonas campestris bacteria literally eat a supply of this corn sugar under controlled conditions, and the digestion process converts the individual sugars into a single substance with properties similar to cornstarch. Xanthan gum is used in dairy products and salad dressings as a thickening agent and stabilizer. Xanthan gum prevents ice crystals from forming in ice creams, and also provides a 'fat feel' in low or no-fat dairy products.
Another use for xanthan gum is the stabilization and binding of cosmetic products. One advantage of xanthan gum is that a little goes an incredibly long way. Cosmetic manufacturers add a very small amount of xanthan gum to their cream-based products in order to keep the individual ingredients from separating. Despite the use of bacteria during processing, xanthan gum itself is not generally harmful to human skin or digestive systems, though some individuals may find they are allergic to it. Xanthan gum is often used whenever a gel-like quality is sought.
Xanthan gum is also used as a substitute for wheat gluten in gluten-free breads, pastas and other flour-based food products. Those who suffer from gluten allergies should look for xanthan gum as an ingredient on the label.
One lesser-known use of xanthan gum is in the oil industry. Oil companies often use water as a lubricant for oil well pumps, but regular water is not very thick. A natural thickener such as guar gum or xanthan gum can be added to the water in order to increase its viscosity, or thickness. You could think of this as turning tap water into 10W-40 motor oil. The thickened water keeps the drill parts lubricated and displaces more of the natural oil found in the deposit area.