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.