BIOLOGY

Xantham

consists of D-glucosyl, D-mannosyl, and D-glucuronyl acid residues in a molar ratio of 2:2:1 and variable proportions of O-acetyl and pyruvyl residues.

USES

Physical

Applications based on physical properties include use as water-soluble thickeners, gelling agents, and emulsion stabilizers.

These include wide use as a thickener or viscosifier in both food and non-food industries. Xanthan gum is also used as a stabilizer for a wide variety of suspensions, emulsions, and foams.

Chemical

Applications based on specific structural features include the use of bacterial capsular antigens as vaccines, and the use of polysaccharides as metal complexants.

The polysaccharides are classified according to their uses as viscosity-increasing agents and as gelling agents.

A third category includes polysaccharides with specific applications such as tailor-made dextran and pullulan and polysaccharides used as substrates for the preparation of rare sugars.

OTHER HIGH COSTS POLYSACCHARIDES

Three other industrially useful bacterial polysaccharides have been developed.

(a)                      S−130, the extracellular, high viscosity polysaccharide produced by a strain of Alcaligenes, has excellent suspending and heat stability properties useful in oil field drilling, workover and completion, and enhanced oil recovery fluids.

(b)                     S−194 has excellent suspending properties and unusual compatibility with salts, making it useful in agricultural applications, particularly flowable pesticides and liquid fertilizers.

(c)                       S−198 has excellent stability to shear and has potential application in the developing market of water−based lubricants.