Catechu (Black Catechu)

Catechu was described in 1574 by a Portuguese writer ‘Garcia de Orta’ and Dr. Wrath used the scientific process first time to extract catechu. According to him, catechu consists of two parts i.e. kattha and cutch. It is used in India as a masticatory from ancient times. The females used catechu for the colouring purpose of their feet.

  • Synonyms: Kattha, Cutch, Catechu.
  • Biological Source: Black catechu or cutch is an aqueous extract of the heartwood of Acacia catechu Willdenow, concentrated by boiling.
  • Family: Leguminosae.
  • Geographical Source: The plants used for the preparation of catechu are grown in Myanmar and India.

Preparation of Catechu

The trees are felled; bark and sapwood are stripped off from the trunk. Then the dark red heartwood is cutted into chips and boiled with water into earthen vessels. The decoction obtained is strained. This strained liquid is again boiled in iron vessels with continuous stirring until it gets syrupy consistency. The syrupy liquid is allowed to cool. It is spread over leaves of Dipterocarpus tuberculatus Roxburgh, Cassia fistula Linn, etc. which are arranged in a wooden frame or mould. It is kept overnight. Next morning the cutch will be dry and forms brick-like masses weighing about 20 kg. These bricks are broken up for the market.

In another method, the redwood obtained from the tree is cut into chips and kept into the extractor. Then steam is passed through the drug for complete extraction. The extract is allowed to concentrate under vacuum and cooling. The obtained concentrated extract is centrifuged. The kattha cakes will separate and be moulded into different shapes and dried. By this method, the good quality of kattha is ready for market. The cutch is obtained by concentrating the mother liquor left after centrifugation. The cutch is allowed to cool.

Acacia catechu plant and Kattha pieces
Fig.1: Acacia catechu plant and Kattha pieces

Description of Catechu

  • Colour: Dull brownish to black.
  • Odour: Odourless.
  • Taste: Astringent and subsequently sweet.
  • Size: Near about 2.0 cm × 5.0 cm.
  • Shape: Cube like or brick-shaped pieces.
  • Solubility: A brown magma forms with cold water but with boiling water, it dissolves entirely and crystalline sediment is deposited upon cooling.
  • Chemical Constituents: The chief constituents are catechu tannin acid (25-33%) and acacatechin (10-12%). Other constituents are catechu red, gum, quercitin and quercitrin.

Chemical Test of Catechu

  1. When the drug is treated with vanillin and hydrochloric acid, it produces pink or red colour due to the presence of catechin.
  2. Add ferric ammonium sulphate to the aqueous solution of the drug, green colour develops which turns to purple by the addition of sodium hydroxide.
  3. To the aqueous solution of the drug, add lime water brown colour produced which turns into reddish precipitate after some time.
  4. Test for catechin: Dip a matchstick in the test solution, dry it and moist it with concentrated hydrochloric acid. Then warm the stick near flame. The colour of the wood changes to pink due to the formation of phloroglucinol.

Uses of Catechu

Catechu is used as an astringent, cooling, and digestive action whereas cutch is not used medicinally. It is used for dyeing and tanning purposes like fishing nets etc.

Chemical structures of Catechin and Catechol
Fig.2: Chemical structures of Catechin and Catechol


Similar extracts are prepared from other substances and called cutch. Thus mangrove cutch is obtained from the bark of Rhizophora mangle Linn and of Ceriops candolleana Arnold, family Rhizophoraceae which contains 42 percent tannins.

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