turmeric

turmeric, (Curcuma longa), perennial herbaceous plant of the ginger family, the tuberous rhizomes (underground stems), of which have been used from antiquity as a condiment, a textile dye, and medically as an aromatic stimulant. Native to southern India and Indonesia, turmeric is widely cultivated on the mainland and in the islands of the Indian Ocean. The rhizome has a pepperlike aroma and a somewhat bitter warm taste and has a strong staining orange-yellow color.

Uses

In ancient times turmeric was used as a perfume as well as a spice and dye. It is the ingredient that colors and flavors prepared mustard and is used in curry powder, relishes, pickles, and spiced butters for vegetables, in fish and egg dishes, and with poultry, rice, and pork. An essential flavor in many South Asian cuisines, turmeric is consumed daily by millions of people.

In parts of Asia turmeric water has long been applied as a cosmetic to lend a golden glow to the complexion, and it has grown in popularity as an ingredient in cosmetics and skin care products elsewhere. It is also one of the sources of the brilliant colors used to celebrate Holi in India and Nepal.

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Reputed to have anti-inflammatory properties, turmeric is sometimes consumed as a tea or in pill form for a variety of ailments, including arthritis and intestinal problems. It is also sometimes used to flavor betel quids for chewing.

Paper tinged with a tincture of turmeric, on addition of alkali, turns from yellow to reddish brown and becomes violet on drying, thus providing a test for alkalinity.

Physical description

Turmeric plants reach about 1 meter (3.3 feet) in height and bear long simple leaves with long petioles (leaf stems). The leaves emerge from the branching rhizomes that lie just below the soil surface. Older rhizomes are somewhat scaly and brown, while young rhizomes are pale yellow to brown-orange. The small yellow-orange flowers are borne in the axils of waxy bracts that are usually pale green or tinged with purple.

Production and lead contamination

Production involves a boiling process, which is followed by exposure of the rhizomes to sunlight for five to seven days to dry. Then they are polished by hand rubbing or by rotation in a mounted drum. Dried rhizomes vary from about 2.5 to 7.5 cm (1 to 3 inches) in length. The spice is usually sold in ground form. Distillation yields 1.3 to 5.5 percent essential oil, the main components of which are turmerone and ar-turmerone. The coloring matter is curcumin, which is also an antioxidant.

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In the 2000s high levels of lead in the blood of pregnant women and children in rural Bangladesh and in members of the Bangladeshi diaspora in New York City attracted the attention of health researchers, who ultimately uncovered dyed turmeric as the culprit. For more than three decades turmeric wholesalers in Bangladesh had been adulterating polished turmeric rhizomes with yellow lead chromate (PbCrO₄) to enhance the rhizomes’ color, unaware of the compound’s neurotoxic effects. A key spice in Bangladeshi cuisine, the presence of lead in turmeric posed significant risks to human health and development in the region and beyond (see lead poisoning). Indeed, one study found in rural Munshiganj district that 78 percent of about 300 young children had elevated blood lead levels from turmeric consumption. Officials in Bangladesh acted with urgency once the source was discovered, issuing public notices warning consumers and vendors to avoid the brightly colored rhizomes and conducting awareness campaigns for turmeric farmers and millers about the legal and health consequences of adding lead chromate. In addition, contaminated turmeric was confiscated and destroyed. A 2019 study of spices in the United States found lead contamination in turmeric purchased from Bangladesh, India, Nepal, Pakistan, and Morocco, suggesting that adulteration continues to pose a public health challenge.