Description
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% and can be used in lower
concentrations. The viscosity of xanthan gum solutions decreases
with higher shear rates; This is called pseudoplasticity. This
means that a product subjected to shear, whether from mixing,
shaking or even chewing, will thin out, but once the shear forces
are removed, the food will thicken back up. A practical use would
be in salad dressing: The xanthan gum makes it thick enough at rest
in the bottle to keep the mixture fairly homogeneous, but the shear
forces generated by shaking and pouring thins it so it can be
easily poured. When it exits the bottle, the shear forces are
removed and it thickens back up so it clings to the salad. Unlike
other gums, it is very stable under a wide range of temperatures
and pH.
In foods, xanthan gum is most often found in salad dressings and
sauces. It helps to stabilize the colloidal oil and solid
components against creaming by acting as an emulsifier. Also used
in frozen foods and beverages, xanthan gum creates the pleasant
texture in many ice creams. Toothpaste often contains xanthan gum,
where it serves as a binder to keep the product uniform. Xanthan
gum is also used in gluten-free baking. Since the gluten found in
wheat must be omitted, xanthan gum is used to give the dough or
batter a "stickiness" that would otherwise be achieved with the
gluten. Xanthan gum also helps thicken commercial egg substitutes
made from egg whites to replace the fat and emulsifiers found in
yolks. It is also a preferred method of thickening liquids for
those with swallowing disorders, since it does not change the color
or flavor of foods or beverages.
In the oil industry, xanthan gum is used in large quantities,
usually to thicken drilling fluids. These fluids serve to carry the
solids cut by the drilling bit back to the surface. Xanthan gum
provides great "low end" rheology. When the circulation stops, the
solids still remain suspended in the drilling fluid. The widespread
use of horizontal drilling and the demand for good control of
drilled solids has led to the expanded use of xanthan gum. Xanthan
gum has also been added to concrete poured underwater, in order to
increase its viscosity and prevent washout.
In cosmetics xanthan gum is used to prepare water gels usually in
conjunction with bentonite clays. Is also used in oil-in-water
emulsions to help stabilise the oil droplets against coalescence.
It has some skin hydrating properties
