Gum karaya or gum sterculia, also known as Indian gum tragacanth, is a vegetable gum 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 Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with w ...

composed of the

sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or do ...

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 Rhamnose (Rha, Rham) is a naturally occurring deoxy sugar. It can be classified as either a methyl-pentose or a 6-deoxy- hexose. Rhamnose predominantly occurs in nature in its L-form as L-rhamnose (6-deoxy-L-mannose). This is unusual, since most ...

and

galacturonic acid -Galacturonic acid is a sugar acid, an oxidized form of -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 Biology 20 ...

. 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 An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Althoug ...

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 adhesive. It is also used to adulterate Gum tragacanth due to their similar physical characteristics. As a

food additive Food additives are substances added to food to preserve Taste, flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), sal ...

it has

E number E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...

E416. Gum karaya can be obtained from the tree ''

Sterculia urens ''Sterculia urens'' is a species of plant in the family Malvaceae. It is native to India and has been introduced into Burma. A small to medium-sized tree with a pale-coloured trunk, it is commonly known as the ''bhutyā'' ( भुत्या) in ...

''. 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 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