What is Nigella Sativa?
Nigella Sativa is a flowering plant, native to southwest Asia that grows to 20-30 cm tall with linear leaves. The flowers are delicate, and usually colored pale blue and white, with 5-10 petals. The fruit is a large and inflated capsule composed of 3-7 united follicles, each containing numerous seeds. The seed is used as a spice.
There is a huge understanding about the names of this spice. Nigella Sativa seed is also known as Kalonji (Hindi), Kezah (Hebrew), Habbat-el-barakah (literally seeds of blessing Arabic) or Siyah Daneh (Persian). In English, it is called Fennel Flower, Black Caraway, Nutmeg Flower or Roman Coriander. Other names used, sometimes misleadingly, are Onion Seed and Black Sesame. Frequently the seeds are referred to as Black Cumin; this is, however, also used for a different spice, Bunium Persicum. It is also sometimes just referred to as Nigella or Black Seed. An old English name gith is now used for the corn cockle.
Nigella Sativa belongs to the Plant family of Ranunculaceae (buttercup family). Nigella seeds have little odour, but when ground or chewed they develop a vaguely oregano-like scent. The taste is aromatic and slightly bitter; I have seen it called “pungent” and “smoky” and even compared to black pepper, but I cannot agree with that comparison. There is, however, some pungency in unripe or not yet dried seeds.
Nigella Sativa originated probably from Western Asia. Although nigella is not mentioned in the common Bible translations, there is good evidence that an obscure plant name mentioned in the Old Testament means nigella; if true, this would indicate that nigella is cultivated since far more than two millennia. Today, the plant is cultivated from Egypt to India.
The seeds contain numerous esters of structurally unusual unsaturated fatty acids with terpene alcohols (7%); furthermore, traces of alkaloids are found which belong to two different types: isochinoline alkaloids are represented by nigellimin and nigellimin-N-oxide, and pyrazol alkaloids include nigellidin and nigellicin.
In the essential oil (avr. 0.5%, max. 1.5%), thymoquinone was identified as the main component (up to 50%) besides p-cymene (40%), a-pinene (up to 15%), dithymoquinone and thymohydroquinone. Other terpene derivatives were found only in trace amounts: Carvacrol, carvone, limonene, 4-terpineol, citronellol. Furthermore, the essential oil contains significant (10%) amounts of fatty acid ethyl esters. On storage, thymoquinone yields dithymoquinonene and higher oligocondensation products (nigellone).
The seeds also contain a fatty oil rich in unsaturated fatty acids, mainly linoleic acid (50 – 60%), oleic acid (20%), eicodadienoic acid (3%) and dihomolinoleic acid (10%) which is characteristic for the genus. Saturated fatty acids (palmitic, stearic acid) amount to about 30% or less. Commercial nigella oil (“Black Seed Oil”, “Black Cumin Oil”) may also contain parts of the essential oil, mostly thymoquinone, by which it acquires an aromatic flavour.