Daucus carota Seeds | Black Carrot
LATIN NAME: Daucus carota
COMMON NAME: Black Carrot
Plant Profile
The carrot is a biennial, and its first season makes a taproot with two distinct tissues: a core of xylem and an outer cortex of phloem. Where the colour sits explains what a cut carrot looks like. In orange lines the carotenes are concentrated in the core; in purple lines the anthocyanins are laid down in the cortex, so a purple-skinned carrot so often shows orange flesh beneath.
The foliage is finely divided and two or three times pinnate, and the second-year plant raises a flat-topped umbel of small white flowers. Look closely at the centre of that umbel and there is usually a single dark purple floret, thought to mimic an insect and draw pollinators to the whole head. The seed is a bristly schizocarp that splits into two mericarps with oil canals along the ribs.
Carrot diversity runs from Afghanistan through Iran and Anatolia, and the earliest cultivated roots there were purple or yellow rather than orange. The orange carrot is a European selection, and the older colours became regional specialities. Black-rooted forms survived in Turkey, Afghanistan, Egypt and parts of India because they kept well and because their juice was valued as a dye as much as a food.
To make the drink at home, slice the roots, salt them heavily and ferment them with cracked wheat in water until the liquid turns deep purple and sour. The acidity comes from lactic fermentation, the colour from the acylated anthocyanins, and the result is served cold with the solids.
Roast black carrots with cumin and oil until the edges caramelise and the purple darkens almost to black; the sugars concentrate and the earthiness recedes. They pickle well in vinegar, keeping both colour and crunch, and they can be grated raw into salads, where the pigment bleeds into the dressing and stains everything it touches.
Science & Biotechnology
The pigment is an anthocyanin, and the black carrot version is unusually well decorated: cyanidin 3-O-(2-O-xylosyl-6-O-glucosyl)galactoside, acylated with caffeic, ferulic, sinapic and p-coumaric acids. Those acyl groups fold back over the chromophore in a process called intramolecular copigmentation, shielding it from the water around it. The result is a pigment that resists heat, light and pH change.
A grape-skin extract in a soft drink fades within months; a black carrot concentrate in the same bottle holds its colour much longer, and the difference is entirely due to the acylated structure. That is why the concentrate displaces other plant colourants in beverages, jams, confectionery and dairy products, and why it is approved as a natural colourant in the European Union.
Because the colour trade needs a consistent raw material, breeding programmes select for anthocyanin content and root yield together, and cell-suspension cultures of Daucus carota have been used to study the biosynthetic pathway. The other compounds of interest are the polyacetylenes falcarinol and falcarindiol, studied for cytotoxic activity and also the reason some people react on handling carrots.
Uses & Benefits
The root still has a working life in the regions that kept it. In southern Anatolia it is the base of a sour, salty fermented drink made with bulgur and turnip, sold from carts and drunk with grilled food; in Afghanistan it is sliced and dressed with vinegar and salt as a street snack; in Egypt and Iran it goes into pickles and stews.
Growing from Seed
Carrot seed is small and slow to establish, so the bed has to be prepared properly. Dig it deep in the previous season and work the surface to a fine tilth, adding well-rotted compost but never fresh manure, which forks and burns the roots. Sow thinly about 1 cm deep in drills 25 to 30 cm apart, and keep the surface damp until the seedlings are up.
Thin at the two-to-three true-leaf stage to 4 to 6 cm apart, watering the row the evening before so the roots come out cleanly. Sow a maincrop in late spring and a second sowing in late summer for a winter crop, the one to aim for if flavour matters, because frost converts starch to sugar in the root. Never let the bed dry out and then soak it, since uneven moisture splits the roots.
Carrot fly is the worst of the pests: the adults are drawn by the smell of crushed foliage, which is why thinning should be done in the evening and the thinnings carried away, and a barrier of fine mesh 60 cm high around the crop is the most reliable protection. The willow-carrot aphid transmits the viruses behind motley dwarf. Alternaria leaf blight and cavity spot are the common diseases, and violet root rot appears in wet ground. Lift the roots before the soil freezes, twist off the tops rather than cutting them, and store them in boxes of damp sand in a cool shed.
Our Take
I grow black carrots for the colour as much as the flavour: a handful grated into a salad turns the whole bowl purple, and the juice makes a stain no shop-bought colourant matches. For a mixed row, the purple carrot lines are the nearest relatives in the catalogue, the dependable Nantes carrot will give you the orange roots they were selected away from, and the fat, short Kuroda carrot is the best of the group for heavy ground.
Related Reading
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