Broccoli (from the Italian plural of broccolo, referring to "the flowering top of a cabbage") is a plant of the Kale family Brassicaceae (formerly Cruciferae). It is classified in the Italica cultivar group of the species Brassica oleracea. Broccoli has large flower heads, usually green in color, arranged in a tree-like fashion on branches sprouting from a thick, edible stalk. The mass of flower heads is surrounded by leaves. Many varieties of broccoli are perennial. Broccoli most closely resembles cauliflower, which is a different cultivar group of the same species.
Broccoli is usually boiled or steamed, but may be eaten raw and has become popular as a raw vegetable in hors d'oeuvre trays. Boiling reduces the levels of suspected anti-cancer compounds in broccoli, with losses of 20 - 30% after five minutes, 40 - 50% after ten minutes, and 77% after thirty minutes. However, other preparation methods such as steaming, microwaving, and stir frying had no significant effect on the compounds. Steaming broccoli for 3-4 minutes is recommended to maximize the anti-cancer compound, sulforaphane.
Nutritional and medicinal
Broccoli is high in vitamins C, K, and A, as well as dietary fiber; it also contains multiple nutrients with potent anti-cancer properties, such as diindolylmethane and small amounts of selenium. A single serving provides more than 30 mg of Vitamin C and a half-cup provides 52 mg of Vitamin C. The 3,3'-Diindolylmethane found in broccoli is a potent modulator of the innate immune response system with anti-viral, anti-bacterial and anti-cancer activity. Broccoli also contains the compound glucoraphanin, which can be processed into an anti-cancer compound sulforaphane, though the benefits of broccoli are greatly reduced if the vegetable is boiled. Broccoli is also an excellent source of indole-3-carbinol, a chemical which boosts DNA repair in cells and appears to block the growth of cancer cells. Broccoli has the highest levels of carotenoids in the brassica family. It is particularly rich in lutein and also provides beta-carotene.
A high intake of broccoli has been found to reduce the risk of aggressive prostate cancer. Broccoli consumption has also been shown to be beneficial in the prevention of heart disease.
There are three commonly grown types of broccoli. The most familiar is a often referred to simply as "broccoli", and sometimes calabrese named after Calabria in Italy. It has large (10 to 20 cm) green heads and thick stalks. It is a cool season annual crop.
Sprouting broccoli has a larger number of heads with many thin stalks. It is planted in May to be harvested during the winter or early the following year in temperate climates. The heirloom variety "calabrese" available in North America is of this type.
Romanesco broccoli has a distinctive fractal appearance of its heads, and is yellow-green in colour. It is technically in the Botrytis (cauliflower) cultivar group.
Purple cauliflower is a type of broccoli sold in southern Italy, Spain, and the United Kingdom. It has a head shaped like cauliflower, but consisting of tiny flower buds. It sometimes, but not always, has a purple cast to the tips of the flower buds.
Other cultivar groups of Brassica oleracea include cabbage (Capitata Group), cauliflower (Botrytis Group), kale and collard greens (Acephala Group), kohlrabi (Gongylodes Group), and Brussels sprouts (Gemmifera Group). Chinese broccoli (Alboglabra Group) is also a cultivar group of Brassica oleracea.