General Introduction
Tragacanth is a natural gum obtained from the dried sap of several species of the genus Astragalus. It has been used for centuries in traditional medicine and various industries for its excellent emulsifying, thickening, and stabilizing properties. Tragacanth gum is prized for its viscosity, stability in acidic conditions, and ability to form gels.
Chemistry of Tragacanth
Chemical Nature:
Composition: Tragacanth is a complex mixture of polysaccharides, primarily composed of tragacanthin and bassorin.
Main Components:
Tragacanthin: A water-soluble fraction that forms a viscous solution.
Bassorin: A water-insoluble fraction that swells in water to form a gel.
Structure: The polysaccharides in tragacanth gum consist of a backbone of galacturonic acid, arabinose, xylose, and fucose units.
Molecular Formula:
The general molecular formula for the polysaccharide fraction is (C6H10O5)n, where n indicates the number of repeating sugar units.
Sources of Tragacanth
Botanical Source:
Species: Astragalus gummifer, Astragalus microcephalus, and other species of Astragalus.
Family: Fabaceae
Geographical Distribution: Native to arid and semi-arid regions of the Middle East, including Iran, Turkey, and Syria.
Preparation of Tragacanth
1. Collection: The gum is harvested by making incisions in the bark of Astragalus plants, allowing the sap to exude and harden on the plant surface. The hardened gum is collected manually after a period of drying.
2. Processing:
Cleaning: The collected gum is cleaned to remove impurities such as bark and dirt.
Sorting: The gum is sorted based on color and size, with the highest quality gum being the lightest in color.
Grinding: The gum is ground into a fine powder for various applications.
Evaluation of Tragacanth
1. Physicochemical Properties:
Solubility: Tragacanth swells in water to form a gel; tragacanthin is soluble in water, while bassorin is insoluble.
Viscosity: The viscosity of tragacanth solutions depends on concentration and temperature.
pH: Typically between 5.0 and 6.5 in a 1% aqueous solution.
Gel Strength: Measured in terms of the ability to form firm gels.
2. Quality Control:
Purity: Assessed by measuring ash content, moisture content, and the absence of contaminants.
Identification Tests: Includes tests for the presence of carbohydrates, such as Molisch’s test and specific optical rotation.
Microbiological Testing: Ensures the absence of harmful bacteria and fungi.
3. Functional Properties:
Emulsifying Capacity: Evaluated by measuring the stability of emulsions formed with oil and water.
Binding and Adhesive Properties: Assessed in tablet formulations and as a binding agent in various pharmaceutical preparations.
Preservation and Storage
Storage Conditions: Tragacanth should be stored in a cool, dry place, away from direct sunlight and moisture to prevent degradation and microbial contamination.
Packaging: Typically stored in airtight containers or bags to protect from environmental factors.
Shelf Life: When stored properly, tragacanth can have a shelf life of several years without significant loss of functionality.
Therapeutic Uses of Tragacanth
1. Traditional Medicine: Used for its soothing and anti-inflammatory properties in treating sore throats, coughs, and gastrointestinal disorders. Employed as a demulcent to protect mucous membranes.
2. Modern Pharmaceuticals:
Excipient: Used as an emulsifier, stabilizer, binder, and suspending agent in various pharmaceutical formulations, including tablets, capsules, syrups, and topical preparations.
Laxative: Acts as a bulk-forming laxative, promoting bowel movements by increasing stool bulk and water content.
Commercial Utility
1. Food Industry:
Thickener and Stabilizer: Utilized in sauces, salad dressings, and ice creams to improve texture and stability.
Emulsifier: Used in various food products to create stable emulsions.
2. Cosmetics:
Thickener and Stabilizer: Used in cosmetics and personal care products, such as lotions, creams, and gels, to enhance texture and stability.
3. Textiles:
Sizing Agent: Employed in the textile industry as a sizing agent to strengthen yarn and reduce breakage during weaving.
4. Printing and Painting:
Used as a binder in watercolor paints and other artistic materials.
Conclusion
Tragacanth is a versatile natural polysaccharide with significant applications in pharmaceuticals, food industry, cosmetics, textiles, and other industrial sectors. Its unique gelling, thickening, and stabilizing properties, along with its biocompatibility, make it an invaluable resource across various fields. Proper evaluation, preservation, and storage are essential to maintain its quality and efficacy.
