Guar flour, Jaguar gum
Guar gum is the powder of endosperm of seeds of Cyamopsis tetragonolobus Linn. belonging to family Leguminosae.
The plants are cultivated mainly in Gujarat, Maharashtra, Karnataka, Rajasthan and Pakistan by seed germination technique.
Colour: It is colourless or pale yellowish-white coloured powder.
Taste: Gummy and characteristic.
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.
It is dispersible in water forming a thick colloidal solution. It is insoluble in alcohol.
Ash: Not more than 1%.
Acid insoluble ash: Not more than 0.5%.
Loss on drying: Not more than 8%.
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.
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).
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.