Xanthan gum is a long chain polysacharide composed of
the sugars glucose, mannose, and glucuronic acid. The backbone
is similar to cellulose, with added sidechains of trisacharides
(three sugars in a chain).
A polysacharide is a chain of sugars.
Some familiar polysacharides are starch and cellulose.
It is a slimy gel 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.
Xanthan gum is used as a thickener in sauces, as an agent in ice cream
that prevents ice crystals from forming, and as a fat substitute that
adds the "mouth feel" of fat without the calories. It is used in canned
pet food to add "cling".
In pastry fillings, it prevents "weeping" (syneresis
) of the
water in the filling, protecting the crispness of the crust.
It has a very high viscosity (thickness) even when very little is
When mixed with
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 trisacharide
side chains of mannose and glucuronic acid make the molecule rigid,
and allow it to form a right-handed helix. These features make it
interact with itself and with other long chain molecules to form
thick mixtures and gels in water.
By Simon Quellen Field