Catechu (// or //) is an extract of acacia trees used variously as a food additive, astringent, tannin, and dye. It is extracted from several species of Acacia, but especially Senegalia catechu (Acacia catechu), by boiling the wood in water and evaporating the resulting brew. It is also known as cutch, black cutch, cachou, cashoo, terra Japonica, or Japan earth, and also katha in Hindi, kaat in Marathi, khaira in Odia, khoyer in Assamese and Bengali, and kachu in Malay (hence the Latinized Acacia catechu chosen as the Linnaean taxonomy name of the type-species Acacia plant which provides the extract).
As an astringent it has been used since ancient times in Ayurvedic medicine as well as in breath-freshening spice mixtures—for example in France and Italy it is used in some licorice pastilles. It is also an important ingredient in South Asian cooking paan mixtures, such as ready-made paan masala and gutka.
The catechu mixture is high in natural vegetable tannins (which accounts for its astringent effect), and may be used for the tanning of animal hides. Early research by Humphry Davy in the early 19th century first demonstrated the use of catechu in tanning over more expensive and traditional oak extracts.
Under the name cutch, it is a brown dye used for tanning and dyeing and for preserving fishing nets and sails. Cutch will dye wool, silk, and cotton a yellowish-brown. Cutch gives gray-browns with an iron mordant and olive-browns with a copper mordant.
- "catechu". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- Cutch and catechu plant origin Archived 2019-02-10 at the Wayback Machine from the Food and Agriculture Department of the United Nations. Document repository accessed November 5, 2011
- Derivation of word from Malay
- Goodwin, Jill (1982). A Dyer's Manual. London: Pelham Books Ltd. p. 60. ISBN 978-0-7207-1327-5.
- Valli Herman (29 October 2003). "They drink this stuff?". LA Times. Retrieved 11 March 2019. See this reference for the use of the dye in vodka
- Tanning, Dye & Processing Materials
- Buchheister G.A.: Handbuch der Drogisten-Praxis. Zweite Auflage, Springer, 1891, p. 322, Catechu at the Internet Archive.