CAS Number: 9000-65-1
E Number: E413
Tragacanth is a kind of natural gum extracted from several species of Middle Eastern legumes of the genus Astragalus, including A. adscendens, A. gummifer, A. brachycalyx, A. microcephalus, A. tragacanthus. Some of these species are known collectively under the common names “goat’s thorn” and “locoweed”. The name “TRAGACANTH” comes from the appearance of the exuded gum, which tends to form ribbons similar in appearance to a goat Thorn (from the Greek “tragos” meaning goat and “akantha” meaning Thorn). The gum is sometimes called shiraz gum, shiraz, gum elect or gum dragon.
The primary source of gum tragacanth is the desert highlands of northern and western Iran, particularly the Zagros Mountains region. Iran is the largest producer of best quality Tragacanth gum. In Iran, the gum is harvested seasonally by making an incision on the upper part of the taproot and collecting the exuding gum. The ribbons of gum are brought to trade centers for processing and exportation.
Uses of Tragacanth Gum:
- Gum tragacanth is a viscous, odorless, tasteless, water-soluble mixture of polysaccharides obtained from sap which is drained from the root of the plant and dried.
- The gum seeps from the plant in twisted ribbons or flakes which can be powdered.
- It absorbs water to become a gel, which can be stirred into a paste.
- The gum is used in vegetable-tanned leatherworking as an edge slicking and burnishing compound, and is occasionally used as a stiffener in textiles.
- The alkaloid it contains has historically been used as an herbal remedy for such conditions as cough and diarrhea.
- As a mucilage or paste, it has been used as a topical treatment for burns.
- It is used in pharmaceuticals and foods as an emulsifier, thickener, stabilizer, and texturant additive.
- Gum tragacanth is also used to make a paste used in floral sugarcraft to create life-like flowers on wires used as decorations for cakes. It makes a paste which air-dries brittle and can take colorings. It enables users to get a very fine, delicate finish to their work.
- Additionally, it has traditionally been used as an adhesive in the cigar-rolling process used to secure the cap or “flag” leaf to the finished cigar body.
- Gum tragacanth is also used in incense-making as a binder to hold all the powdered herbs together. Its water solubility is ideal for ease of working and an even spread. Only half as much is needed, compared to gum arabic or something similar
- Gum tragacanth is less common in products than other gums, such as gum arabic or guar gum, largely because most tragacanth is grown in Middle Eastern countries which have shaky trade relations with countries where the gum is to be used.
Properties of Tragacanth Gum:
- Tragacanth contains from 20% to 30% of a water-soluble fraction called tragacanthin (composed of tragacanthic acid and arabinogalactan).
- It also contains from 60% to 70% of a water-insoluble fraction called bassorin.
- Tragacanthic acid is composed of D-galacturonic acid, D-xylose, L-fructose, D-galactose, and other sugars.
- Tragacanthin is composed of uronic acid and arabinose and dissolves in water to form a viscous colloidal solution (sol), while bassorin swells to form a thick gel.
- Tragacanthin partially dissolves and partially swells in water yielding a viscous colloid.
- The maximal viscosity is attained only after 24 hours at room temperature or after heating for 8 hours at high temperatures.
- The viscosity of these solutions is generally considered to be the highest among the plant gums. The solutions are stable to heat and under a wide range of pH levels.