Xanthan (415) is a cold soluble hydrocolloid used for thickening and stabilising. Xanthan can synergistically modify the gel texture and viscosity of other hydrocolloids.
|Oil – Water dressings||Emulsion stabilisation and viscosity control.|
|Syrups and toppings||Viscosity control and cocoa suspension.|
|Baked goods||Prevents lump formation during kneading and improves dough homogeneity.|
|Pastry fillings||Viscosity and syneresis control.|
|Soups, sauces and marinades||Viscosity control.|
|Whipped creams & mousses||Air cell stabilisation.|
|Instant mixes||Rapid thickening, suspension and provides body.|
Xanthan gum (E 415) is a long chain polysaccharide composed of the sugars’ glucose, mannose, and glucuronic acid. The backbone is similar to cellulose, with added sidechains of trisaccharide's (three sugars in a chain). These features make it interact with itself and with other long chain molecules to form thick mixtures and extremely viscous sols in water.
It is an extremely viscous sol produced by the bacterium Xanthomonas campestris, which causes black rot on cruciferous vegetables such as cauliflower and broccoli. The slime protects the bacterium from viruses, and prevents it from drying out.
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, on the order of one percent. In most foods, it is used at 0.5% w/w, or even as low as 0.05% w/w.
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 must not seem 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 stabilisation properties.
Unlike other gums, it is very stable under a wide range of temperatures and pH.
When mixed with guar gum or locust bean gum, the viscosity is more than when either one is used alone, so less of each can be used.
The backbone of Xanthan gum is similar to cellulose, but the trisaccharide side chains of mannose and glucuronic acid make the molecule rigid and allow it to form a right-handed helix.
The secondary structure of the Xanthan molecule, in which the side chains are ‘wrapped around’ the cellulose backbone, explains the unusual resistance of this hydrocolloid to degradation by acids or bases, high temperatures, freezing and thawing, enzymes and prolonged mixing.