GUAR GUM

SYNOMYMS: Guar flour, Jaguar gum, Guaran

BIOLOGICAL SOURCE: It is the powder of the endosperm of the seeds of Cyamopsis tetragonolobus Linn belonging to the family Leguminosae.

GEOGRAPHICAL SOURCE: It is indigenous to India. It is cultivated in Pakistan, USA, etc.

COLLECTION AND PREPARATION:  The guar gum is manufactured from the white well developed seeds that are free from foreign matter. Using grinder the seeds are parted and separated into husk and cotyledons containing embryo. Cotyledons are separated from endosperm by winnowing. Further the endosperm is pulverised in a micro pulveriser and grinded for 15 minutes. Again the process of grinding is carried out for 3-4 hrs followed by sifting. This process is repeated for 5-6 times for several hours to give white coloured guar gum. Finally it is sifted using sieve of 40-60 mesh size to get powdered guar gum.

CHARACTERS: Colourless or pale yellowish white coloured powder, characteristic odour, gummy taste, swells rapidly in water neutral to litmus, Ash value-NMT 1%, Acid insoluble ash-NMT 0.5%, Loss on drying- NMT8%

CHEMICAL CONSTITUENTS: The contents are divided into water- soluble and water- insoluble parts. The water soluble fraction consisting about 85% of the gum is known as Guaran, which is a high molecular wt hydro colloidal polysaccharide. Guaran on hydrolysis yields 65% galactose and 35% of mannose, which are combined through glycosidic linkage. Guar gums also contain 5-7% of proteins.

IDENTIFICATION TESTS:

1.      It does not acquire olive green colour with weak solution of Iodine.

2.      It does not acquire pink colour with solution of ruthenium red.

3.      About 2% solution of lead acetate gives precipitate with the solution of guar gum.

4.   To the aqueous solution of guar gum add 0.5 ml hydrogen peroxide and 0.5 ml of benzidine in alcohol. No blue colour is produced.

5.      Aq. Solution of guar gum is converted to a gel by small amount of borax.

USES: Guar gum is used as a thickening agent, as a tablet binder and disintegrating agent, as an emulsifying agent, as a protective colloid, stabilizer, thickening and film forming agent for cheese, ice creams, soups, in pharmaceutical jelly formulations, in suspensions, emulsions, lotions, creams, tooth pastes, bulk laxative, appetite depressant, in peptic ulcer therapy, extensively used as flocculent in ore-dressing, and treatment of water.