Gum karaya or gum sterculia, also known as Indian gum tragacanth, is a

vegetable gum Natural gums are polysaccharides of natural origin, capable of causing a large increase in a solution's viscosity, even at small concentrations. They are mostly botanical gums, found in the woody elements of plants or in seed coatings. Human u ...

produced as an exudate by trees of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Sterculia ''Sterculia'' is a genus of flowering plants in the mallow family, Malvaceae: subfamily Sterculioideae (previously placed in the now obsolete Sterculiaceae). Members of the genus are colloquially known as tropical chestnuts. ''Sterculia'' ma ...

''. Chemically, gum karaya is an acid polysaccharide composed of the sugars

galactose Galactose (, '' galacto-'' + ''-ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molecu ...

, rhamnose and

galacturonic acid -Galacturonic acid is a sugar acid, an oxidized form of galactose, -galactose. It is the main component of pectin, in which it exists as the polymer polygalacturonic acid.Debra Mohnen "Pectin structure and biosynthesis" Current Opinion in Plant B ...

. It is used as a

thickener A thickening agent or thickener is a substance which can increase the viscosity of a liquid without substantially changing its other properties. Edible thickeners are commonly used to thicken sauces, soups, and puddings without altering their t ...

and emulsifier in foods, as a

laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...

, and as a

denture Dentures (also known as false teeth) are prosthetic devices constructed to replace missing teeth, and are supported by the surrounding soft and hard tissues of the oral cavity. Conventional dentures are removable ( removable partial denture or ...

adhesive. It is also used to adulterate Gum tragacanth due to their similar physical characteristics. As a food additive it has E number E416. Gum karaya can be obtained from the tree '' Sterculia urens''. It is a valuable substance and is traditionally tapped by cutting or peeling back the bark, or by making deep gashes at the base of the trunk with an axe. These crude methods of extraction often resulted in the death of the tree, but it has been found that application of the plant growth regulator

ethephon Ethephon is a plant growth regulator. Mechanism of action Upon metabolism by the plant, it is converted into ethylene, a potent regulator of plant growth and ripeness. It is also a butyrylcholinesterase inhibitor. Uses in various crops Etheph ...

stimulates the production of gum, and when used in carefully controlled amounts, increases gum yield and enhances healing of the wounds and survival of the tree.

References

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External links

Sterculia Gum
Natural gums Edible thickening agents Medicinal plants E-number additives