Coriander

Coriander (/ˌkɒriˈændər, ˈkɒriændər/), whose leaves are known as cilantro (/sɪˈlæntroʊ, -ˈlɑːn-/) is an annual herb (Coriandrum sativum) in the family Apiaceae.

Most people perceive the leaves as having a fresh, slightly citrus taste. Due to variations in the gene OR6A2, some people perceive it to have a soap-like taste, or even a pungent or rotten taste.

It is native to the Mediterranean Basin. All parts of the plant are edible, but the fresh leaves, the dried seeds, and the roots are the parts most traditionally used in cooking. It is used in certain cuisines, like Peruvian, Mexican, Indian and Southeast Asian.

It is a soft plant growing to 50 cm (20 in) tall. The leaves are variable in shape, broadly lobed at the base of the plant, and slender and feathery higher on the flowering stems.

The flowers are borne in small umbels, white or very pale pink, asymmetrical, with the petals pointing away from the centre of the umbel longer (5–6 mm or 3⁄16–1⁄4 in) than those pointing toward it (only 1–3 mm or 1⁄16–1⁄8 in long). The fruit is a globular, dry schizocarp 3–5 mm (1⁄8–3⁄16 in) in diameter. The pollen size is approximately 30 μm (0.0012 in).

The essential oil from coriander leaves and seeds contains mixed polyphenols and terpenes, including linalool as the major constituent accounting for the aroma and flavour of coriander.

Different people may perceive the taste of coriander leaves differently. Those who enjoy it say it has a refreshing, lemony or lime-like flavour, while those who dislike it have a strong aversion to its pungent taste and smell, characterizing it as soapy or rotten. Studies also show variations in preference among different ethnic groups: 21% of East Asians, 17% of Caucasians, and 14% of people of African descent expressed a dislike for coriander, but among the groups where coriander is popular in their cuisine, only 7% of South Asians, 4% of Hispanics, and 3% of Middle Eastern subjects expressed a dislike.

About 80% of identical twins shared the same preference for the herb, but fraternal twins agreed only about half the time, strongly suggesting a genetic component to the preference. In a genetic survey of nearly 30,000 people, two genetic variants linked to the perception of coriander have been found, the most common of which is a gene involved in sensing smells. The gene OR6A2 lies within a cluster of olfactory-receptor genes, and encodes a receptor that is highly sensitive to aldehyde chemicals. Flavour chemists have found that the coriander aroma is created by a half-dozen substances, most of which are aldehydes. Those who dislike the taste are sensitive to the offending unsaturated aldehydes and, at the same time, may be unable to detect the aromatic chemicals that others find pleasant. Association between its taste and several other genes, including a bitter-taste receptor, have also been found.