Title: Karaya Gum
CAS Registry Number: 9000-36-6
Additional Names: Gum karaya; kadaya; katilo; kullo; kuteera; sterculia; Indian tragacanth; mucara
Literature References: The dried exudate of the tree Sterculia urens Roxb., Sterculiaceae, found in India, especially in the Gujerat region and in the central provinces: Toothaker, The Soluble Gums (Philadelphia, 1921); Mantell, The Water-Soluble Gums (New York, 1947). Constituents and structure: Hirst, Dunstan, J. Chem. Soc. 1953, 2332. Structure is a partially acetylated polysaccharide containing about 8% acetyl groups and about 37% uronic acid residues. Reviews: F. Smith, R. Montgomery, The Chemistry of Plant Gums and Mucilages (Reinhold, New York, 1959); Goldstein, Alter, in Industrial Gums, R. L. Whistler, Ed. (Academic Press, New York, 2nd ed., 1973) pp 273-287.
Properties: Finely ground white powder, faint odor of acetic acid. Acid to litmus. Absorbs water rapidly to form viscous mucilages at low concs. Viscosity decreases on addn of acid or alkali. Color of the soln lightens in acidic media and darkens in alkaline soln due to the presence of tannins. Gum karaya loses viscosity forming ability when stored in the dry state, the loss being greater for a powdered material than for the crude gum. Cold storage inhibits this degradation.
NOTE: Karaya gum occurring in broken irregular pieces having a somewhat crystalline appearance has been referred to commercially as 'crystal' gum.
Use: As denture adhesive; as binder in paper manuf; as stabilizer, thickener, texturizer, emulsifier in foods; as thickening agent for dyes in textile industry. A substitute for gum tragacanth.