Karaya gum

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A dried gummy exudate from Sterculia urens trees native to central and northern India. Karaya gum occurs as tears of variable size and of a somewhat crystalline appearance. The tears are a translucent, pale yellow, with a slightly acetic odor and a mucilaginous, slightly acetic taste. Karaya is a partially acetylated polysaccharide with about 8% acetic groups and 37% uronic acid residues that contains Rhamnose, Galactose, and galacturonic acid. It is acidic to Litmus. Karaya gum is insoluble in alcohol, but swells in water to form a Gel. Gum karaya, which has only been available commercially since 1920, forms an extremely strong adhesive with small amounts of water. It is used as a medical adhesive, dye thickener, textile coating, emulsifier, and paper fiber binder.

Synonyms and Related Terms

gomme de karaya (Fr.); goma karaya (Esp.); kadaya gum; Indian tragacanth; Indian gum; bassora gum; kuteera gum; sterculia gum; gum hog; gum karaya; katilo; kulo; mucara

Physical and Chemical Properties

Swells in cold water. Insoluble in ethanol.

CAS 9000-36-6

Resources and Citations

  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • John S. Mills, Raymond White, The Organic Chemistry of Museum Objects, Butterworth Heineman, London, 2nd ed., 1994
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 5296