Synonyms

Tragacanth gum

Tragant

Definition

Tragacanth is a dried exudation obtained from the stems and branches of natural strains of Astragalus gummifer Labillardiere and other Asiatic species of Astragalus (family Leguminosae). It consists mainly of high molecular weight polysaccharides (galactoarabans and acidic polysaccharides) which, 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

Molecular weight

Approximately 800 000

Einecs

232-252-5

Description

Unground Tragacanth gum occurs as flattened, lamellated, straight or curved fragments or as spirally twisted pieces 0,5-2,5 mm thick and up to 3 cm in length. It is white to pale yellow in colour but some pieces may have a red tinge. The pieces are horny in texture, with a short fracture. It is odourless and solutions have an insipid mucilaginous taste. Powdered tragacanth is white to pale yellow or pinkish brown (pale tan) in colour

Identification

1 g of the sample in 50 ml of water swells to form a smooth, stiff, opalescent mucilage; insoluble in ethanol and does not swell in 60 % (w/v) aqueous ethanol

Purity

Negative test for Karaya gum

Boil 1 g with 20 ml of water until a mucilage is formed. Add 5 ml of hydrochloric acid and again boil the mixture for five minutes. No permanent pink or red colour develops

Loss on drying

Not more than 16 % (105 ^oC, 5 hours)

Total ash

Not more than 4 %

Acid insoluble ash

Not more than 0,5 %

Acid insoluble matter

Not more than 2 %

Arsenic

Not more than 3 mg/kg

Lead

Not more than 5 mg/kg

Mercury

Not more than 1 mg/kg

Cadmium

Not more than 1 mg/kg

Heavy metals (as Pb)

Not more than 20 mg/kg

Salmonella spp.

Negative in 10 g

E. coli

Negative in 5 g