Karaya gum is used in cosmetics and food, and in pharmaceuticals as a laxative and adhesive.
Karaya gum has been used commercially for about 100 years. Its use became widespread during the early 20th century, when it was used as an adulterant or alternative for tragacanth gum. However, experience indicated that karaya possessed certain physiochemical properties that made it more useful than tragacanth; furthermore, karaya gum was less expensive. Traditionally, India is the largest producer and exporter of karaya gum. Increasing amounts are exported by African countries. Currently the gum is used in a variety of products, including cosmetics, hair sprays, and lotions.
Karaya gum is a complex, partially acetylated polysaccharide obtained as a calcium and magnesium salt. The polysaccharide component of karaya has a high molecular weight and is composed of galacturonic acid, beta-D-galactose, glucuronic acid, L-rhamnose, and other residues. , ,
The quality of karaya gum depends on the thoroughness of impurity removal. Food-grade gum is usually a white to pinkish gray powder with a slight vinegar odor. Pharmaceutical grades of karaya may be almost clear or translucent.
Karaya gum is the least soluble of the commercial plant exudates, but it absorbs water rapidly and swells to form viscous colloidal solutions even at low concentrations (1%). The swelling behavior of karaya gum is dependent upon the presence of acetyl groups in its structure. Deacetylation through alkali treatment results in a water soluble gum. When used in higher concentrations in water (up to 4%), karaya forms gels or pastes. Unlike other gums, karaya swells in 60% alcohol, but remains insoluble in other organic solvents. Karaya may absorb up to 100 times its weight in water.
Because the gum is partially acetylated, it may release acetic acid during storage.