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 "
Swells in cold water. Insoluble in ethanol.
Sources Checked for Data in Record
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- 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
- Encyclopedia Britannica, http://www.britannica.com Comment: "Gum." Encyclopædia Britannica. 2 Sept. 2004 .
- Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000