The Cabbage Family: Turnip, Radish

The turnip, Brassica rapa, has been under cultivation for about 4,000 years in Eurasia as a staple, fast-growing food. It consists of both lower stem and taproot, can have a number of different shapes and colors, and has the sulfury aroma typical of the family. Small, mild varieties may be eaten raw and crunchy like radishes, larger ones cooked until soft: but not too long, or the overcooked cabbage flavor dominates and the texture becomes mushy. Turnips are also pickled.

The crisp, sometimes pungent radish is a different species, Raphanus sativus, a native of western Asia, and had reached the Mediterranean by the time of the ancient Egyptians and Greeks. Like the turnip it’s mainly a swollen lower stem, and has been shaped by human selection into many distinctive forms and striking colors (for example, green at the surface and red inside). Most familiar in the United States are small, early-maturing spring varieties, usually with a bright red skin, which take only a few weeks to grow, and become harsh and woody in summer heat. These are usually eaten raw in salads. But there are also large Spanish and German varieties, some with black skins and some white, that reach several inches in diameter and mature over several months for harvest in the autumn. These types are firm and dry, and take well to braising and roasting. And there are the large, long white Asian radishes, best known by the Japanese term daikon, which can be more than a foot/25 cm long and weigh 6 lb/3 kg. They are relatively mild and used both raw and cooked, sometimes almost as a crisp pear might be. Radish pungency is created by an enzyme reaction that forms a volatile mustard oil. Much of that enzyme is found in the skin, so peeling will moderate the pepperiness. Though most often eaten raw or pickled, radishes can be cooked like turnips, a treatment that minimizes their pungency (the enzyme is inactivated) and brings out their sweetness.