Source & Processing
Gum Tragacanth is the dried, gummy exudation obtained from Astragalus gummifer or other Asiatic species of Astragalus. This plant is a small, low, bushy perennial shrub having a large tap root, which, along with the branches, is tapped for the gum.
The plants grow wild in the dry deserts and mountains of Asia Minor, Iran, Syria, and Turkey. Iran is the largest exporter and supplies the best quality. The plants are tapped by making careful longitudinal incisions in the tap root and the bark of the branches. The gum exudes readily from these cuts in the form of ribbons or flakes, which become brittle on drying. The plants requite an abundance of water during the growing season, but need a dry climate during the collecting time, which extends from April to September for ribbons and from August to November for flakes. Collections are first brought to trading centers and then to wholesale markets where they are hand sorted, graded, packed, and shipped.
The uses of Tragacanth are dependent on high viscosity at low concentration, suspending action, stability to heat and acidity, effective emulsifying properties, and extremely long shelf life.
Pharmaceuticals and Cosmetics
Tragacanth is used in a wide variety of medicinal emulsions, jellies, syrups, ointments, salves, lotions, and creams as a thickener, emulsifier and lubricant. By increasing the viscosity of the external phase, the gum suspends and prevents the active ingredients from settling out. Tragacanth is used in cod liver oil emulsions to facilitate the absorption of poorly soluble substances, such as steroid glycosides and fat-soluble vitamins. It is also used in low-calorie elixirs and syrups. Tragacanth acts as a suspending agent in various toothpastes to form a creamy, brilliant product. Its long shelf life and film-forming properties make it useful in hair lotions, and hand lotions and creams.
Tragacanth has been used in textile print paste and sizes for high quality silks and crepes. It has good release properties and gives added body to these fabrics. It is also used in dressing leather and in the preparation of leather polishes. In addition, it is used in furniture, floor, and auto polishes. It has been used as and adhesive for reconstituted cigar wrapper leaves as well.
Because of its relative stability to heat, acidity, and aging, Tragacanth is widely used as a thickener and stabilizer in pourable salad dressings of the regular and low calorie types. For similar reasons, it is used in relish sauces, condiment bases, sweet pickles, liquors, and mayonnaise. It is used at about 0.4–0.75% in the above products. Tragacanth provides clarity and brilliance to frozen pie fillings and toppings in which suspended fruit, fruit purees and flavors are used. The gum gives good shelf life to these acidic products.
Fruit nectars, consisting of pure fruit puree, artificial fruit juices, sugar, ascorbic acid, and citric acid and about 0.2 – 0.8% of total weight. It has replaced Tragacanth in many pickle and relish sauces where rapid cooling is used.
Tragacanth improves the shelf life and reduces syneresis when sued as a cold process stabilizer for meringues. In combination with gum Arabic, Tragacanth produces a superior bakery flavor emulsion. In citrus beverages, Tragacanth acts as a thickening agent to impart proper mouth feel and stability Since the gum has good acid resistance, it has been used in candy cream centers containing natural fruit and acid. It has also been used as a binder in the cold-press process and the extrusion process for making candy cigarettes, and lozenges.