DESCRIPTION

Tragacanth is a dried, gummy exudation obtained from the stems and branches of Astragalus gummifer Labillardiere, or other Asiatic species of Astragalus (Fam. Leguminosae). It consists mainly of high-molecular-weight polysaccharides (arabinogalactans and acidic polysaccharides) that, on hydrolysis, yield galacturonic acid, galactose, arabinose, xylose, and fucose; small amounts of rhamnose and of glucose (derived from traces of starch and/or cellulose) may also be present. Unground tragacanth occurs as flattened, lamellated, frequently curved fragments or straight or spirally twisted linear pieces from 0.5 to 2.5 mm in thickness. It is white to weak yellow (although some pieces may have a red tinge) and translucent, with a horny texture and a short fracture. It is easier to pulverize if heated to 50°. Powdered tragacanth is white to yellow-white or pink-brown.