Xanthan

Structural description

Xanthan gum is a bacterial polysaccharide produced by a process involving fermentation of glucose by the Xanthomonas campestris bacterium.

Xanthan gum chain consists of repeating modules of five sugar units. The backbone of the polysaccharide chain consists of two β-D-glucose units linked through the 1 and 4 positions and the side chain consists of two mannose and one glucuronic acid. The side chain is linked to every other glucose of the backbone at the 3 position. About half of the terminal mannose units have a pyruvic acid group linked as a ketal to its 4 and 6 positions. The other mannose unit has an acetyl group at the 6 positions.

Activities and Uses

Xanthan gum is used as a food additive (thickener, stabilizer) and rheological modifier. It is accepted as a safe food additive in the USA, Canada and Europe, with E number E415. In cosmetics xanthan gum is used to prepare water gels usually in conjunction with bentonite clays. It is also used in oil-in-water emulsions to help stabilise the oil droplets against coalescence. It has some skin hydrating properties.