Catechu (/ˈkætɪʃuː/ or/ˈkætɪtʃuː/)[1] is an extract of acacia trees used variously as afood additive,astringent,tannin, anddye. It is extracted from several species ofAcacia, but especiallySenegalia catechu (previously calledAcacia catechu), by boiling the wood in water and evaporating the resulting brew.[2] The Malay namekachu is the basis of the Latinized[3]catechu chosen as theLinnaean taxonomy name of the plant species which provides the extract.
As anastringent it has been used since ancient times inAyurvedic medicine as well as in breath-freshening spice mixtures—for example in France and Italy it is used in somelicoricepastilles. It is also an important ingredient in South Asian cookingpaan mixtures, such as ready-madepaan masala andgutka.
The catechu mixture is high in natural vegetabletannins (which accounts for its astringent effect), and may be used for thetanning of animal hides. Early research byHumphry Davy in the early 19th century first demonstrated the use of catechu in tanning over more expensive and traditional oak extracts.
Under the namecutch, it is a brown dye used fortanning and dyeing and for preservingfishing nets andsails. Cutch will dyewool,silk, andcotton a yellowish-brown. Cutch gives gray-browns with anironmordant and olive-browns with acopper mordant.[4]
Black catechu has recently also been used by Blavod Drinks Ltd. to dye theirvodka black.[5]
White cutch, also known as gambier, gambeer, or gambir, which is extracted fromUncaria gambir[6] has the same uses. Palm-catechu is extracted from the seeds ofAreca catechu.[7]
The catechu extract gave its name to thecatechin andcatechol chemical families first derived from it. Its historic name is "Japanese Earth" or "Japanese Dirt", which is responsible for naming "Japanic acid".
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