Raphanus sativus L.
Radish is an edible root vegetable that belongs to the polymorphic species Raphanus sativus in the cabbage family (Cruciferae, Brassicaceae), together with cabbage, broccoli and turnip. It’s very variable in form, shape and size and is grown and eaten throughout the world.
The world production of radish is estimated at 7 million ton per year, about 2% of the world production of vegetables (PROTA)
Radish is a vegetable of the temperate regions. In the tropics it performs best at higher latitudes, above 10°C (50ºF) during the cool season and in highlands above 1000m.
Radish plants can be small leafy annuals with small globular or oval roots or biennials with tapering or cylindrical, large fleshy roots.
The edible part is the thickened hypocotyl (in globe radish) and thickened hypocotyl and upper tap root in the larger white radish. In both cases it’s just known as the edible root.
The size of radish is variable from about the size of a ping pong to 40 inches (100cm, 1 metre) long, if left to grow.
The weight is variable from a few grams (ounces) to 2.5 kg (5Ib) to 20kg (44Ib). The shape varies from globular, to oval to cylindrical and tapering.
The colour of the skin varies from white to pink, red, purple, yellow, green, grey to black. The skin is mostly thin, but can be thick especially in the black radish. The flesh is usually white and crisp. The flavour varies from mild to hot (pungent).
Common Cultivars of Radish
The Red Globe
The red globe radishes are small, round or oval-shaped. They are also called ‘button’ red radishes. They are usually red in colour but can be yellow, purple or white.
Size: they range in size from about 1.5-5 inches (2.5-13cm in diameter, but the smaller 1-1½ inch (2.5-4cm) diameter ones are more popular because larger ones tend to be pithy.
The flesh is solid and crisp.
They are usually sold bunched with their leaves intact or topped (with leaves removed). Topped radishes are sold in plastic bags.
Small young spring radishes are pungent due to presence of glucosides. They are mostly eaten raw or used to garnish dishes.
They are popular for salads or ‘piquant hors d’oeuvre’. They are also used to add colour to or garnish dishes.
The daikons are native to Asia. They are very large and carrot shaped. They can grow up to 18 inches (45cm) long and weigh 1-2 pounds (0.5-1kg). They are also called Japanese or oriental radishes.
The domestic daikons in the USA-Canada have a white flesh that is juicy and a bit hotter than that or red radishes but milder than that of black ones.
Also known as Black Spanish
This is a large radish with dark grey-brown or black skin. It’s turniplike in size and shape and is about 8-inches (20cm) long. ‘Black Spanish’ is the name for commercially grown black radish which can be round or long in shape.
The flesh is white, quite pungent and drier than other radishes. In Europe they are called Black radish.
California Mammoth Whites
These ones have oblong shaped roots about 8 inches (20cm) long . The flesh is slightly pungent .
These ones are long and tapered and up to 6 inches (15cm)-long. They have a thin skin and a pure white flesh that is milder than that of red radishes.
Comprises Chinese radish, Japanese radish and Mooli. They are crisp and mild in flavour
The roots are thinly peeled, sliced or diced and added to soups and sauces or cooked with meat.
They can be preserved in salt.
They can also be grated and be eaten raw, in salads.
The leaves are eaten as a salad or spinach
Radish sprouts are also edible lightly sautéed or stir fried
Rat tailed Radish
Also called “Mogri”
Rat tailed radish is grown for the immature, crisp, green or purple, 20-60cm long pods. It’s important in India and eastern Asia.The crisp fleshy fruits are consumed raw, cooked or pickled. The root of this cultivar is not edible.
Oil Seed Radish
There are forms of radish that are used as oil seed crop,
The leaf radish is gaining importance in Europe and South Africa as a forage and green manure
How to Buy Radish
Radish is usually marketed either bunched (with the leaves attached to the edible root) or topped (with the leaves trimmed off). In both cases the roots are usually trimmed. The topped radish are usually sold in plastic bags.
Leaves: If the leaves are attached then they should be crisp and turgid and green in colour.
Size: Although globe radish can grow up to 5 inches (13cm) in diameter, the larger ones tend to be pithy so it’s best to buy small radishes of about 1-1½ inches (4cm) in diameter.
Root: whether red or white the edible root should be hard and solid with a smooth unblemished surface. Soft or spongy radishes have lost water and are unpleasant for salads.
Check bagged radishes to ensure they are free of mould (mold).
Black radishes should be solid, heavy and free of cracks (common in Polish or Russian-markets) .
Daikon, in Asian markets or supermarkets should be evenly shaped and firm to the touch. They should have a glossy, almost translucent sheen.
How to Store Radish
If you buy radish with the leaves attached, you should remove them if you don’t plan to use them same day. Radishes don’t keep well with the leaves attached.
The leaves, if fresh are green are edible and can be cooked like spinach or added to soups.
Storing: Place radish in plastic bag in the refrigerator crisper. They will keep up to two weeks.
Black radish can be stored for months if kept dry (moisture will hasten spoilage). Keep in perforated bags in refrigerator crisper.
How to Prepare Radish
Scrub the radish and trim off the stem end and root tip.
Most of the enzymes responsible for pungency are found in the skin so you may want to lightly peel the skin with a paring knife or vegetable peeler.
Red globes and white icicles are usually not peeled. The red globe skin is used as a garnish or to add colour to salads or dishes.
Daikons have a very thin skin that can be removed if you prefer. Use a vegetable peeler.
Black radishes tend to have a thicker skin and should be scrubbed thoroughly. If the skin is thin you can leave it on for it’s striking black colour and white flesh, if not it should be peeled.
Red and white radishes are sold all the year round, but are plentiful in spring.
In the USA the largest growers are California and Florida (encyclo)
Black radishes have a longer shelf life and are at their peak in winter and early spring.
Daikons are most flavourful in fall and winter.
Point to Note
“Bunched radishes are very popular because turgid, dark green leaves are perceived by consumers to be an indicator of freshness; but bunched radishes are very perishable due to leaf yellowing and shrivelling that renders the product unattractive, limiting its marketability
(Hassell 2004). It is likely that attached leaves exacerbate water loss from radish roots by
increasing the surface area for transpiration and drawing water out of the roots.” (Journal of food quality)