Gum tragacanth (Astragalus, fam. Leguminosae)


Gum tragacanth is the natural exudate from Southwest Asiatic Astragalus species, mainly found in Iran and Turkey. Gum exudes after hand incisions made on the root of the plant and is collected in the shape of ribbons or flakes.

Gum tragacanth – INS 413;E 413; GRAS 21CFR184-1351; European Pharmacopeae 01/2005:0532 – is defined by the EC food Regulation 231/2012 as “ a dried exudation obtained from the stem and branches of strains of Astragalus gummifer Labillardiere and other Asiatic species of Astragalus (family Leguminosae)…”

Due to high viscosity at low concentration (1 to 2 %) in water solution, purification of the raw gum can only be made with dry process. Quality control inspections of each batch of collected gum are necessary to ensure production of consistent quality of the final powder. Selected batches are mechanically ground to a fine powder, usually below 150 µ to insure a fast hydration in water. Throughout the grinding process, foreign matters (mainly vegetable and mineral impurities) are removed by selective sieving, aspirating and density table separation. The finish fine powder meets the regulatory and specific end user specifications.

Gum tragacanth is described as a complex, highly branched, slightly acidic polysaccharide with high molecular weight (approximately 850 000 daltons).

In water solution, gum tragacanth develops high viscosity (from 400 to 4000 mPa s-Brookfield) at low concentration (1 to 2 %). Viscosity depends upon the grade; ribbons giving the highest viscosity.

Due to its protein content (1 to 3 %) which reduces the surface tension at the interface oil/water of an emulsion and its strong pseudoplastic rheological behaviour, gum tragacanth is an emulsifier- stabiliser of choice for liquid or viscous emulsions.

Molecule of gum tragacanth shows strong resistance against hydrolysis in acidic medium and usefull suspending properties (very good stability in solution from pH 2 to 8).

Stabilisation of acidic emulsions such as salad dressings is one of main application of this gum.

Gum tragacanth is used in food industry as food additive and as excipient in pharmaceutical specialities. Emulsifier, stabiliser and thickener are the main functionalities of this gum.

In dressings and sauces, gum tragacanth stabilises the acidic oil in water and water in oil emulsions. Liquid or creamy dressings are formulated using low dosage (0,2 to 0,8 %) of gum. Addition of gum tragacanth in low calorie dressings with reduced oil content matches the mouthfeel of the regular formula.
In confectionery, gum tragacanth is use as a binder and emulsifier in lozenges production to bring cohesion to the tablet and better release of the flavour.

For icings gum tragacanth is part of many formulations. The gum bind the water in high sugar solids systems. This moisture retention prevents drying, flaking and cracking of the icings.
In pharmaceutical applications, gum tragacanth is a thickener and suspending agent for syrups, lotions and tablets.
Gum tragacanth is used for its viscosity and film forming properties in cosmetics for hair fixator creams often in association with other natural gums.

  • Gum tragacanth fact sheet
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  • EC food Regulation 231/2012
    PDF 564 KB
  • History, Production, and Uses of Tragacanth
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  • Enzymatic Depolymerization
    PDF 564 KB