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Tragacanth refers to a natural gum which is derived from the stem of a small shrub of the species Astralgus that is originally found in the Middle East. Also known as goat's thorn or locoweed, the plant gets its name from the Greek words tragos which means goat and akantha which means thorn. The stem of the plant exudes a gum which is commonly called gum elect, shiraz gum, or gum dragon. This gum is harvested for use as a food additive.
Tragacanth is a stabilizer, emulsifier, and thickener in many foods. Thickeners, also called thickening agents, are substances which increase the viscosity of foods without affecting their flavor. Guar gum and tragacanth are two of the most common edible thickening agents. This gum also has practical applications in stiffening fabrics, artist's pastels, and leatherworking.
The gum is removed from the shrubs by cutting slits or punctures into the stem. Tragacanth will ooze through the openings where it can then be collected. It is generally harvested in long ribbons which resemble the goats' horns after which it is named. This gummy sap is a water soluble carbohydrate that is not suitable for the production of chewing gum like chicle, but is suited for altering the composition of foods without changing the taste.
Before the gum is used as a food additive, it is typically dried and ground into a fine powder. The resulting product may be off-white or cream colored. As a food additive, tragacanth is nearly odorless, tasteless, and colorless making it an additive that does not generally change the flavor of the food. Some food products which contain tragacanth include jellies, mayonnaise, sauces, and syrups. Popsicles, ice cream, liqueurs, and candy sometimes contain this food additive also. Textiles and pharmaceuticals including lozenges and emulsions also sometimes contain tragacanth.
There have been some reported instances of allergic reaction to this gum when used as a food additive. Although uncommon, allergic reactions may range from runny nose and watery eyes to breathing problems and anaphylactic shock. This food additive also tends to be susceptible to contamination from bacteria.
There are more than 2000 species of Astralgus, but the most common source of tragacanth is the Astralgus gummifer Labillardiere. The gum may also come from the species Astralgus Microcephalus Willd. The main components of this dried sap are polyarabinan-trigalaetangeddic acid and bassorin. Water, trace amounts of starch, cellulose, and nitrogenous substances are also contained in tragacanth.
Iran is the largest producer of quality tragacanth gum, particularly the Zagros Mountains region of the country. Other suppliers in West Asia include the countries of Pakistan and Turkey.