Xanthan Gum is a type of sugar (a Polysaccharide) produced by the fermentation of corn using a growing medium to yield the gum which is then purified, dried and ground to a fine powder. It has some unusual properties which make is ideal for some food applications. When the powder is added to liquid to form a gum solution it displays pseudoplasticity (shear thinning) properties; this means the viscosity of the solution is reduced when shear forces are applied (i.e. stirring, mixing or shaking), the viscosity increases again once the shear forces are removed. For example, Xanthan Gum is used in salad dressings to increase the viscosity when the bottle is stationary (preventing the herbs, oil and water from mixing) then when the bottle is shook or mixed the viscosity is reduced making it easy to pour on to your salad.