Xanthan gum
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Xanthan gum is a natural gum polysaccharide used as a food additive and rheology modifier. It is produced by a biotechnological process involving fermentation of glucose or sucrose by the Xanthomonas campestris bacterium. It was discovered by an extensive research effort by the United States Department of Agriculture, which involved the screening of a large number of biopolymers for their potential uses.
One of the most remarkable properties of xanthan gum is its capability of producing a large increase in the viscosity of a liquid by adding a very small quantity of gum of the order of one percent. In most foods it is used at 0.5% or as low as 0.05%. The viscosity of xanthan gum solutions decreases with higher shear rates, this is called pseudoplasticity. Foods need high viscosity at low shear rates to be stable. But when consumed they cannot seem to be thick and heavy in the mouth. Due to the pseudoplastic properties of xanthan gum it can seem thin in the mouth (fairly high rates of shear) but still have good stabilization properties. Unlike other gums it is very stable under a wide range of temperatures and pH, and is accepted as a safe food additive in USA and Europe, with E number E415.
In foods, xanthan gum is most often found in salad dressings and sauces. It helps to stabilize the colloidal oil and solid materials found in these products. It is also used in frozen foods and beverages. Toothpaste often contains xanthan where it serves as a binder to keep the product uniform. In the oil industry xanthan gum is used in large quantities. In most cases, the xanthan gum is used to thicken drilling fluids. These fluids serve to carry the solids cut by the drilling bit back to the surface. The widespread use of what are called horizontal wells and their demand for good control of drilled solids has lead to the expanded use of xanthan gum.
Xanthan has also been used to bind fine tobacco solids together so that they can be formed into a strip that is used to extend the normal cut tobacco leaves.
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