Kale or borecole is a form of cabbage (Brassica oleracea Acephala Group), green or purple, in which the central leaves do not form a head. It is considered to be closer to wild cabbage than most domesticated forms. The species Brassica oleracea contains a wide array of vegetables including broccoli, cauliflower, collard greens, and brussels sprouts. The cultivar group Acephala also includes spring greens and collard greens, which are extremely similar genetically.
Kale is very high in beta carotene, vitamin K, vitamin C, lutein, zeaxanthin, and reasonably rich in calcium. Kale, as with broccoli and other brassicas, contains sulforaphane (particularly when chopped or minced). Boiling decreases the level of sulforaphane; however, steaming, microwaving, or stir frying do not result in significant loss. Along with other brassica vegetables, kale is also a source of indole-3-carbinol, a chemical which boosts DNA repair in cells and appears to block the growth of cancer cells. Kale is also a good source of carotenoids.
Kales can be classified by leaf type:
Curly leaved (Scots Kale)
Leaf and spear (a cross between curly leaved and plain leaved Kale)
Cavolo nero (also known as black cabbage, Tuscan Cabbage, Tuscan Kale, Lacinato and dinosaur Kale)
Because Kale can grow well into winter, one variety of Rape Kale is called ‘Hungry Gap’, named after the period in winter in traditional agriculture when little could be harvested.
Kale freezes well and actually tastes sweeter and more flavourful after being exposed to a frost.
Tender kale greens can provide an intense addition to salads, particularly when combined with other such strongly flavoured ingredients as dry-roasted peanuts, tamari-roasted almonds, red pepper flakes, or an Asian-style dressing.
In the Netherlands it is very frequently used in the winter dish stamp pot and seen as one of the country’s traditional dishes, called boerenkool.
In Ireland kale is mixed with mashed potatoes to make the traditional dish colcannon. It is popular on Halloween when it is sometimes served with sausages. Small coins are sometimes hidden inside as prizes.
Kale is a very popular vegetable in China, Taiwan, and Vietnam, where it commonly stir-fried with beef.
Many varieties of kale are referred to as “flowering kales” and are grown mainly for their ornamental leaves, which are brilliant white, red, pink, lavender, blue or violet in the interior or the rosette. Most plants sold as “ornamental cabbage” are in fact kales. Ornamental kale is as edible as any other variety, provided it has not been treated with pesticides or other harmful chemicals.
When uncooked, standard Kale is a popular garnish.