Tragacanth

• BPTragacanth
• JPTragacanth
• Ph. Eur.Tragacanth
• USP–NFTragacanth

Gum tragacanth; tragacanth gum; gum dragon; tragacantha; E413

Dried gummy exudation from Astragalus gummifer Labillardière and other Asian Astragalus species · [9000-65-1]

Polymer, mixture or material of variable composition — no single molecular formula applies.

Gelling agent, viscosity modifier

Typical concentrations: — · Dosage forms: Liquid, Semi-solid

Used as a suspending agent and emulsifier in oral liquids and lotions, commonly at about 0.5–2% w/v, and as a thickener in creams, gels and jellies. It has also been used as a tablet and lozenge binder, and is widely used in foods.

Occurs as flattened, ribbon-like, white to pale yellow, translucent flakes or as a white to yellowish-white powder. It is odourless and has a mucilaginous taste. Chemically it is a complex mixture of acidic polysaccharides containing galacturonic acid, galactose, arabinose, xylose and fucose, with small amounts of protein.

Composition

a water-soluble fraction (tragacanthin) and a larger water-swellable fraction (bassorin, tragacanthic acid)

Viscosity

1% w/v dispersions are typically about 100–4000 mPa·s, depending on grade; the dispersions are pseudoplastic

pH

about 5–6 (1% w/v aqueous dispersion)

Solubility

practically insoluble in water, ethanol and other organic solvents, but swells rapidly in 10 times its weight of hot or cold water to form a viscous colloidal sol or semi-gel

The powder is stable when stored dry. Dispersions reach maximum viscosity after about 24 hours and are most stable at about pH 4–8; heat and extremes of pH reduce viscosity. Dispersions support microbial growth and need a preservative. Store in a well-closed container in a cool, dry place.

Reduces the efficacy of some preservatives, such as benzalkonium chloride, chlorobutanol and methylparaben, whereas phenoxyethanol and benzoic acid are less affected. Strong mineral acids and alkalis reduce viscosity, and high salt concentrations may also lower it.

The gum exudes from incisions made in the roots and stems of the shrubs, mainly in Iran and Turkey; it is collected, dried, sorted into grades and may be milled to powder.

Widely used in foods and oral and topical products and generally regarded as non-toxic and non-irritant. Hypersensitivity reactions, including rare cases of contact dermatitis and anaphylaxis, have been reported. JECFA has allocated an ADI 'not specified'.

Observe normal precautions for the quantity handled. Avoid inhaling the powder; eye protection and a dust mask are recommended.

GRAS listed. Accepted as a food additive in Europe (E413). Included in the FDA Inactive Ingredient Database (oral suspensions, syrups and tablets) and in non-parenteral medicines licensed in Europe.

Acacia; guar gum; karaya gum; xanthan gum.

Iran is a major source of tragacanth, and the ribbon grades are generally of higher quality than the flake grades. Because the gum clumps when added to water, it is best dispersed first in a wetting agent such as ethanol, glycerol or propylene glycol, or mixed with other powders, before water is added. Quality and viscosity vary between natural lots.