Xanthan gum () is a polysaccharide with many industrial uses, including as a common food additive. It is an effective thickening agent, emulsifier, and stabilizer that prevents ingredients from separating. It can be produced from simple sugars by fermentation and derives its name from the species of bacteria used, Xanthomonas campestris.
History
Xanthan gum was discovered by Allene Rosalind Jeanes and her research team at the United States Department of Agriculture, and brought into commercial production by CP Kelco under the trade name Kelzan in the early 1960s. It was approved for use in foods in 1968 and is accepted as a safe food additive in the US, Canada, European countries, and many other countries, with E number E415, and CAS number 11138-66-2.
Xanthan gum derives its name from the species of bacteria used during the fermentation process, Xanthomonas campestris.
Uses
Xanthan gum, 1%, can produce a significant increase in the viscosity of a liquid.
In foods, xanthan gum is common in salad dressings and sauces. It helps to prevent oil separation by stabilizing the emulsion, although it is not an emulsifier. Xanthan gum also helps suspend solid particles, such as spices. Xanthan gum helps create the desired texture in many ice creams. Toothpaste often contains xanthan gum as a binder to keep the product uniform. Xanthan gum also helps thicken commercial egg substitutes made from egg whites, to replace the fat and emulsifiers found in yolks. It is also a preferred method of thickening liquids for those with swallowing disorders, since it does not change the color or flavor of foods or beverages at typical use levels. In gluten-free baking, xanthan gum is used to give the dough or batter the stickiness that would otherwise be achieved with gluten. In most foods, it is used at concentrations of 0.5% or less. Xanthan gum is used in a wide range of food products, such as sauces, dressings, meat and poultry products, bakery products, confectionery products, beverages, dairy products, and others.
In the oil industry, xanthan gum is used in large quantities to thicken drilling mud. These fluids carry the solids cut by the drilling bit to the surface. Xanthan gum provides great "low end" rheology. When circulation stops, the solids remain suspended in the drilling fluid. The widespread use of horizontal drilling and the demand for good control of drilled solids has led to its expanded use. It has been added to concrete poured underwater, to increase its viscosity and prevent washout.
In cosmetics, xanthan gum is used to prepare water gels. It is also used in oil-in-water emulsions to enhance droplet coalescence. Xanthan gum is under preliminary research for its potential uses in tissue engineering to construct hydrogels and scaffolds supporting three-dimensional tissue formation. Furthermore, thiolated xanthan gum (see thiomers) has shown potential for drug delivery, since by the covalent attachment of thiol groups to this polysaccharide high mucoadhesive and permeation enhancing properties can be introduced.
Shear thinning
The viscosity of xanthan gum solutions decreases with higher shear rates. This is called shear thinning or pseudoplasticity. This means that a product subjected to shear, whether from mixing, shaking or chewing will thin. When the shear forces are removed, the food will thicken again. In salad dressing, the addition of xanthan gum makes it thick enough at rest in the bottle to keep the mixture fairly homogeneous, but the shear forces generated by shaking and pouring thins it, so it can be easily poured. When it exits the bottle, the shear forces are removed and it thickens again, so it clings to the salad.
Concentrations used
The greater the concentration of xanthan gum in a liquid, the thicker the liquid will become. An emulsion can be formed with as little as 0.1% (by weight). Increasing the concentration of gum gives a thicker, more stable emulsion up to 1% xanthan gum. A teaspoon of xanthan gum weighs about 2.5 grams and brings one cup (250ml) of water to a 1% concentration.
To make a foam, 0.2–0.8% xanthan gum is typically used. Larger amounts result in larger bubbles and denser foam. Egg white powder (0.2–2.0%) with 0.1–0.4% xanthan gum yields bubbles similar to soap bubbles.
Health
Xanthan gum may have some health benefits. It has slowed tumor growth in mice with skin cancer, stabilized blood sugar, lowered cholesterol and improved the symptoms of dysphagia. Xanthan gum may also act as a laxative.