Contents:
Synonyms:
Guar flour, Jaguar gum
Biological Source:
Guar gum is the powder of endosperm of seeds of Cyamopsis tetragonolobus Linn. belonging to family Leguminosae.
Geographical Source:
The plants are cultivated mainly in Gujarat, Maharashtra, Karnataka, Rajasthan and Pakistan by seed germination technique.
Description:
Colour: It is colourless or pale yellowish-white coloured powder.
Odour: Characteristic.
Taste: Gummy and characteristic.
Extra Features:
When mounted in lactophenol and seen under a microscope, it shows irregular principles of various sizes and shapes. Guar gum swells rapidly in water with a translucent suspension. It’s 0.5 % aqueous solution is neutral to litmus.
Solubility:
It is dispersible in water forming a thick colloidal solution. It is insoluble in alcohol.
Standards:
Ash: Not more than 1%.
Acid insoluble ash: Not more than 0.5%.
Loss on drying: Not more than 8%.
Chemical Constituents:
The contents of guar gum are divided into water-soluble and water-insoluble parts. Water-soluble fraction constituting about 85 % of the gum is known as guaran, which is a high molecular weight hydro-colloidal polysaccharide. Guaran on hydrolysis yields 35 % of galactose and 65 % of mannose, which are combined through glycosidal linkage. Guar gum also contains 5 – 7 % proteins.
Identification:
1. It does not acquire olive green colour with a weak solution of iodine.
2. With the solution of ruthenium red, the gummy solution does not acquire pink colour (distinction from agar and sterculia gum).
3. About 2 % solution of lead acetate gives a precipitate with the solution of guar gum.
4. Dissolve 0.5 g of guar gum in 20 ml of water by shaking. To it add 0.5 ml of hydrogen peroxide and 0.5 ml of 1% solution of benzidine in alcohol. No blue colour is produced (distinction from gum acacia).
Uses:
About 1% mucilage of guar possesses similar viscosity to that of mucilage of acacia and a 3 % mucilage is similar to mucilage of tragacanth. It has 5 to 8 times more thickening power than starch. It is used as a protective colloid, a binding and disintegrating agent, bulk laxative, appetite depressant and in peptic ulcer therapy. Guar gum is a good emulsifying agent by binding bile salts, guar-gum reduces the cholesterol content. Industrially, this is used in paper manufacturing, printing, polishing textiles and also in food and cosmetic industries.