Aim: To perform the identification tests of turmeric
Test-tube, Stirrer, Measuring cylinder, Different reagents and solutions.
Synonyms: Saffron Indian; Haldi (Hindi); Curcuma; Rhizoma cur-cumae.
Biological Source: Turmeric is the dried rhizome of Curcuma longa Linn. (syn.C.domestica Valeton)., belonging to family Zingiberaceae.
The plant is a native to southern Asia and is cultivated extensively in temperate regions. It is grown on a larger scale in India, China, East Indies, Pakistan, and Malaya.
- Turmeric plant is a perennial herb, 60–90 cm high with a short stem and tufted leaves; the rhizomes, which are short and thick, constitute the turmeric of commerce.
- The crop requires a hot and moist climate, a liberal water supply and a well-drained soil. It thrives on any soil-loamy or alluvial, but the soil should be loose and friable.
- The field should be well prepared by ploughing and turning over to a depth of about 30 cm and liberally manured with farmyard and green manures. Sets or fingers of the previous crop with one or two buds are planted 7 cm deep at distance of 30–37 cm from April to August.
- The crop is ready for harvesting in about 9–10 months when the lower leaves turn yellow. The rhizomes are carefully dug up with hard picks, washed, and dried.
Colour: Outer surface is deep yellow to brown
Taste: Aromatic, Pungent and Bitter
Fracture: Horny; Cut surface is waxy, resinous
Size & Size: Primary rhizomes are ovate, pear-shaped, oblong or pyriform or cylindrical called ‘bulb’. Secondary, more cylindrical, lateral branched, tapering on both ends, rhizomes are 4–7 cm long and 1–1.5 cm wide and called as ‘fingers’.
- The transverse section of the rhizome is characterized by the presence of mostly thin-walled rounded parenchyma cells, scattered vascular bundles, definite endodermis, few layers of cork developed under the epidermis, and scattered oleoresin cells with brownish contents.
- The epidermis is consisted of thick-walled cells, cubical in shape, of various dimensions. The cork cambium is developed from the sub-epidermal layers and even after the development of the cork, the epidermis is retained. Cork is generally composed of four to six layers of thin-walled brick-shaped parenchymatous cells.
- The parenchyma of the pith and cortex contains grains altered to a paste, in which sometimes long lens shaped unaltered starch grains of 4–15 μm diameter are found. Oil cells have suberised walls and contain either orange-yellow globules of a volatile oil or amorphous resinous masses.
- Cortical vascular bundles are scattered and are of a collateral type. The vascular bundles in the pith region are mostly scattered and they form discontinuous ring just under the endodermis.
- The vessels have mainly spiral thickenings and only a few have reticulate and annular structure.
- Turmeric contains yellow colouring matter called as curcuminoids (5%) and essential oil (6%).
- The chief constituent of the colouring matter is curcumin I (60%) in addition with small quantities of curcumin III, curcumin II and dihydrocurcumin.
- The volatile oil contains mono- and sesquiterpenes like zingiberene (25%), α-phellandrene, sabinene, turmerone, arturmerone, borneol, and cineole. Choleretic action of the essential oil is attributed to β-tolylmethyl carbinol.
- The volatile oil also contains α- andβ-pinene, camphene, limonene, terpinene, terpinolene, caryophyllene, linalool, isoborneol, camphor, eugenol, curdione, curzerenone, curlone, AR-curcumenes, β-curcumene, γ-curcumene. α- and β-turmerones, and curzerenone.
Chemical Tests :-
- Turmeric powder on treatment with concentrated sulphuric acid forms red colour.
- On addition of alkali solution to Turmeric powder red to violet colour is produced.
- With acetic anhydride and concentrated sulphuric acid Turmeric gives violet colour. Under UV light this colour is seen as an intense red fluorescence.
- A paper containing Turmeric extract produces a green colour with borax solution.
- On addition of boric acid a reddish-brown colour is formed which, on addition of alkalies, changes to greenish-blue.
- Turmeric is used as aromatic, anti-inflammatory, stomachic, uretic, anodyne for billiary calculus, stimulant, tonic, carminative, blood purifier, antiperiodic, alterative, spice, colouring agent for ointments and a common household remedy for cold and cough. Externally, it is used in the form of a cream to improve complexion.
- Dye-stuff acts as a cholagogue causing the contraction of the gall bladder.
- It is also used in menstrual pains.
- Curcumin has choleretic and cholagogue action and is used in liver diseases.
- Curcumin is a nontoxic authorized colour, heat resistant and sensitive to changes in pH.
- Curcuminoids have antiphlogistic activity which is due to inhibition of leukotriene biosynthesis. ar-Turmerone has antisnake venom activity and blocks the haemorrhagic effect of venom.