Curcuma. Turmeric.
Synonyms.—Turmeric Rhizome; Turmeric Root.
Turmeric is the dried rhizome of Curcuma longa, Linn. (N.O. Scitamineae), a native of Southern Asia, largely cultivated in India, China, Java, and other tropical countries. The rhizomes are dug up after the aerial stems have died down, and are then steamed or boiled, by which their vitality is destroyed. They are finally dried in the sun, or in an oven, and sorted into "fingers," the lateral secondary rhizomes, and "bulbs," the stem-producing rhizomes; the latter are sometimes quartered or sliced to facilitate drying. Finger turmeric occurs in long, curved, or nearly straight subcylindrical pieces, bluntly tapering towards either end. The pieces are compact and heavy, of a yellowish-brown colour, and marked externally with longitudinal wrinkles and transverse leaf scars. Some pieces have short branches or show the scars where these have broken off. The fracture is short, the internal surface being of a brownish-yellow waxy appearance, and of a tough and horny consistence. The transverse section exhibits a paler ring separating the stele from the cortex. Bulb turmeric resembles finger turmeric, but is shorter and thicker, and is often in quarters. The odour and taste of turmeric are aromatic and characteristic. Turmeric yields from 5 to 7 per cent. of ash.
Constituents.—The chief constituents of turmeric are curcumin, a yellow crystalline body, and about 5 per cent. of a volatile oil. The rhizome also contains starch and resin, some of the starch being gelatinised owing to the method in which the drug is prepared for market. Curcumin is a yellow crystalline substance which dissolves in alcohol to form a deep yellow solution, alkalies changing the colour to reddish-brown; concentrated sulphuric acid, or better, a mixture of that reagent with alcohol, produces with tissues containing curcumin a deep crimson colouration, a reaction which is often useful in detecting the powdered drug. Boric acid changes it to reddish-brown, which, on the addition of alkalies, becomes greenish-blue.
Action and Uses.—Turmeric is an aromatic, used principally as a constituent of curry powders and other condiments. Tincture of turmeric may be used as a colouring agent, but the colour is fugitive in solution. Turmeric paper is prepared from the tincture, and is used as a test for alkalies and for boric acid.
PREPARATIONS.
- Tinctura Curcumae, B.P.—TINCTURE OF TURMERIC.
- Turmeric, bruised, 1; alcohol, 6. Prepared by the maceration process. Tincture of turmeric is used as a test solution, being turned brown by alkalies, while the original yellow colour is restored by acids, except in the case of boric acid, which gives a reddish-brown colouration, changing to bluish-black on the addition of ammonia. Turmeric paper is prepared by soaking unglazed white paper in the tincture and then drying it.
- Tinctura Curcumae, U.S.P.—TURMERIC TINCTURE U.S.P.
- Prepared by digesting turmeric repeatedly with small quantities of water, discarding the liquid, drying the residue, and macerating it in six times its weight of alcohol (95 per cent.) for several days, and filtering.
