Properties of Tragacanth
pH = 5-6 for a 1% w/v aqueous dispersion.
Less than of equal to 15% w/w
Particle size distribution of Powdered Grades
50% w/w passes through a 73.7 micrometer mesh.
Although insoluble in water, tragacanth gum swells rapidly in 10 times its own weight of either hot or cold water to produce viscous colloidal sols or semigels.
In general, 1% w/v aqueous dispersions may range in viscosity from 100-4000 mPa s (100-4000 cP) at 20oC. However, tragacanth dispersions viscosity varies according to the grade and source of the material. Viscosity increases with increasing temperature and concentration, and decreases with increasing pH. Maximum initial viscosity occurs at pH 8,although the greatest stability of tragacanth dispersions occurs at around pH 5.
Tragacantha, gum tragacanth, locoweed, shiraz gum, gum elect, gum dragon, goat’s thorn (in Greek the word “tragos” means “Goat” and the word “akantha” means “thorn”), trag; tragant, persian tragacanth.
Gum tragacanth is the dried gummy exudation obtained by incisions made on the stems and branches of Astragalus gummifer Labill and other species of Astagalus belonging to the Leguminosae family.
It is indigenous to Greece, Iran, Turkey, Kuwait, Syria and Jordan. Few species of tragacanth are also found in some parts of India like Garhwal, Kumaon and central Punjab.
Persian tragacanth is supplied by Iran and North Syria.Similarly ,Smyrna tragacanth is exported from Smyrna port situated in Asiatic Turkey. The best quality gum is produced in Iran, Iran is also the largest producer of the gum tragacanth.
Gum tragacanth is a natural gum,collected from the shrubs that are thorny and grow at an altitude of 1000m – 3000 m. Tragacanth gum is formed as a result of transformation of the cells of pith and medullary rays into gummy substance. For the collection of gum, incisions are made on various parts of stem and the fluid which oozes out from the incisions is collected after drying.
Produced tragacanth is found in irregular flattened flakes with ribbon like appearance,depending upon the type of incisions made on the plant for collection. Twisted ribbons or flakes are formed when the gum seeps from the plant which is collected and then can be powdered for commercial purposes. This powdered tragacanth on absorbing water, becomes a gel, that can be stirred into paste.
Collection period: It is collected from April to November every year.
Storage of Gum tragacanth: The produced Gum tragacanth is stored and preserved in well-closed air-tight containers.
- Colour- The flakes are white or pale yellowish-white.
- Odour- It is odourless.
- Taste- It has mucilaginous taste.
- Shape- Gum tragacanth occurs in the form of thin,flattened ribbon like flakes, more or less curved.
- Size- Flakes are approximately 25 x 12 x 2 mm in size.
- The gum is horny, translucent with transverse and longitudinal ridges.
- Fracture of the drug is short.
- It is translucent and horny in texture.
The produced tragacanth gum should comply with following standards if intended for human consumption:
- The content of foreign organic matter in the produced tragacanth gum should not exceed 1.0%.
- The sulphated ash of the produced tragacanth gum should not exceed 4.0%.
- The moisture content in the produced tragacanth gum should not exceed 15.0%.
- It should not contain more than 0.001 % of Lead (as per the USP).
- It’s heavy metal content should not exceed 20 microgram per gram of tragacanth gum.
Gum tragacanth contains two fractions, one soluble in water and other fraction is water-insoluble.
- Tragacathin - is the water-soluble portion of tragacanth which constitutes about 8 to 10 % of the gum.
- Bassorin- is the water-insoluble portion of the tragacanth which constitutes about 60 to 70 % of the gum.
- Methoxy group- tragacanth contains about 15% of methoxy group which swells in water.
- Due to the presence of methoxy group as a constituent of the gum ,tragacanth gum has high viscosity.
- Normally, 1.0 % solution of the tragacanth gum has not less than 250 centipoises of viscosity.
- On hydrolysis of the tragacanth, the products are Galactouronic acid, D-galactopyranose, L-arabino-rhamnose and D-xylopyranose.
- Deep yellow precipitate is formed, on boiling the solution of tragacanth with few drops of 10 % aqueous ferric chloride solution.
- Stringy precipitate is formed, on dissolving the tragacanth and precipitated copper oxide in concentrated ammonium hydroxide (conc. NH3OH).
- Canary yellow colour is developed, on warming tragacanth with sodium hydroxide (NaOH) solution.
- It gives green colour with strong iodine solution.
- To rule out Karaya gum as adulterant, boil 1 g of tragacanth in 20 ml of distilled water.When mucilage is formed then add 5 ml of dilute hydrochloric acid and boil the mixture again for 5 minutes. Absence of pink or red colour rules out adultration with Gum Karaya.
- As a demulcent and as an emollient in cosmetics.
- As a stiffener in textile industry.
- As a remedy for cough and diarrhoea, the alkaloid content of the gum is used.
- As a thickening and as an emulsifying agent in pharmaceuticals.
- As a suspending agent along with acacia.
- As a binding agent in the tablets, mucilage of tragacanth is used.
- As an excipient in the pills, mucilage of tragacanth is used.
- As an adhesive, the tragacanth powder is used.
- Also used in lotions for external use and in spermicidal jellies.
- As a stabiliser for ice-creams in 0.2 – 0.3 % concentration and also in sauces.
- As edge slicking and burnishing material in vegetable-tanned leather works.
- The water soluble property of tragacanth gum makes it ideal for ease of work and for spreading it evenly.
- Since long time, in cigar rolling process,this gum is used as an adhesive,by which the cap of cigar is secured to the finished body of cigar.