Derived from a fermentation process by bacteria, xanthan gum was
discovered in the 1950s by American scientists. The microorganism
Xanthomonas Campestri transforms sugars, nitrogen, magnesium
and other minerals into polysaccharides. This transformation is
a little like yeast which, when combined with sugars, produces
alcohol and carbon dioxide.
These micro-organisms occur naturally on plants in the cabbage
family and they are often responsible for the presence of dark
spots on broccoli, cauliflower and other leafy vegetables. In
factories, the bacteria are inoculated in a sterile environment until
their fermentation has finished. The microorganisms are finally
eliminated by heat and the gum is collected through precipitation,
centrifuging and drying.
Xanthan gum belongs to the hydrocolloid family, and like each
member of this family, its molecules must have time to hydrate
after having been dissolved. This hydration period allows water
to penetrate inside hydrocolloid molecules, which then facilitate
reactions as they are surrounded by water and suspended in the
solvent. Hydration can be done equally well in a hot or cold liquid.
Heat only slightly alters the thickening effect of xanthan gum once
the product has cooled, but its viscosity is temporarily decreased
during the process. This additive also tolerates a wide range of pH
and the presence of salts and alcohol up to 60%, but it is best to
complete the hydration phase before these additions.
Xanthan gum is a thickener and stabilizer, but it does not form
a gel. Rather, it suspends particles in salad dressings and gives
sauces their creamy texture. By preventing bread starches from
crystallizing, it also preserves freshness. For this reason, it is
commonly used in bakeries.
Pseudoplasticity is also a property of xanthan gum widely used
by the industry. It consists in the ability of a preparation to change
from a thick, viscous form to an almost liquid state after stirring.
A dressing containing xanthan gum will thus be thick when the
bottle is slowly turned upside down, but its contents become liquid
if the bottle is vigorously shaken before being turned upside down.
It returns to its original viscosity when put back to rest.
Fifty percent of xanthan gum is used outside the food industry,
including cosmetics, personal hygiene products, and the
pharmaceutical industry, where it is also used as a stabilizer.