KARAYA GUM

Description

Sterculia gum (also called gum Karaya, gum kadaya, Indian tragacanth, and India Gum, and by other names) is the dried exudate of Sterculia urens, a tree native to the mountainous regions of central and eastern India. Native collectors tap or drill the trees, and after several days collect the exudate in the form of large, irregular tears that may weigh up to several pounds. The best quality gum is collected during the hot spell (May to June) that precedes the monsoon. The collectors sell the product to dealers who clean and fragment the tears and sort the gum before putting it into export markets. Processors in the United States further purify the gum to remove bark, wood fiber, and soil, then grind, size, and blend the material to obtain uniform grades of gum.
Sterculia gum is also produced from various other species of Sterculia found in India, Africa, Australia, China, and Indochina, but the product is apparently not available separately in commercial amounts. These other gums may be mixed with that from S. urens. Another related gum is produced by species of Cochlospermum.
Sterculia gum is a complex polysaccharide with a high molecular weight of about 9.5 million. The molecule is reported to consist of units of D-galacturonic acid, D-galactose, and L-rhamnose in proportions of 43, 13, and 15 percent, respectively. It has a high acetyl content, with acid numbers reported at between 13.4 and 22.7; on aging or heating, the molecule may split off free acetic acid which gives Sterculia gum a sightly acetous odor.
Sterculia gum absorbs water rapidly to form viscous mixtures at low concentrations; up to 4 percent may be hydrated in cold water to form heavy, viscous pastes. A one percent mixture may have aSterculia gum absorbs water rapidly to form viscous mixtures at low concentrations; up to 4 percent may be hydrated in cold water to form heavy, viscous pastes. A one percent mixture may have a viscosity of 3,330 centipoises. Viscosity decreases with heating and aging. It is used as an emulsifier and food stabilizer.
A dried, gummy exudation from Sterculia urens Roxburgh and other species of Sterculia (Fam. Sterculiaceae), or from Cochlospermum gossypium A. P. De Condolle or other species of Cochlospermum Kunth (Fam. Bixaceae). It occurs in tears of variable size or in broken, irregular pieces having a somewhat crystalline appearance. It is pale yellow to pinkish brown, translucent, and horny, and is sometimes admixed with a few darker fragments and occasional pieces of bark. The gum has a slightly acetous odor and a mucilaginous and slightly acetous taste. In the powdered form it is light gray to pinkish gray. Karaya gum is insoluble in alcohol, but it swells in water to form a gel.

Chemical properties

from sterculia tree

Chemical properties

Gum karaya is the exudate of Sterculia urens, a tall (30 ft) bushy tree, native to India, where it grows in forests of the eastern and central mountains. The trees are tapped and the exudate, which may be several pounds in weight, is collected and sold at auction. Crude gum karaya is cleaned, ground, sized and blended to obtain uniform grades. Impurities range from 0.1 to 3% and consist primarily of bark, but other foreign matter may be present. The part used is exudate from the bark. The gum has a slight vinegar smell.

Occurrence

Karaya gum is a tree found in India and Pakistan.

The Uses of KARAYA GUM

As denture adhesive; as binder in paper manufacture; as stabilizer, thickener, texturizer, emulsifier in foods; as thickening agent for dyes in textile industry. A substitute for gum tragacanth.

The Uses of KARAYA GUM

Used as a thickener and emulsifier

What are the applications of Application

Karaya gum is a thickener and emulsifier

Definition

A hydrophilic polysaccharide which exudes from certain Indian trees of the genus Sterculia. Color varies from white to dark brown or black.

Essential oil composition

Gum karaya is a complex polysaccharide with a very high molecular weight, approximately 9,500,000 daltons. The gum karaya molecule contains D-rhamnose, D-galactose and D-galacturionic acid units. Ratios of 43% D-galacturionic acid, 13% D-galactose and 15% L-rhamnose have been obtained by hydrolysis.