Citrus is a common term and genus (Citrus) of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar (Burma) and the Yunnan province of China. Citrus fruit has been cultivated in an ever-widening area since ancient times; the most well known examples are the oranges, lemons, grapefruit and limes.
These plants are large shrubs or small trees, reaching 5–15 m tall, with spiny shoots and alternately arranged evergreen leaves with an entire margin. The flowers are solitary or in small corymbs, each flower 2–4 cm diameter, with five (rarely four) white petals and numerous stamens; they are often very strongly scented. The fruit is a hesperidium, a specialised berry, globose to elongated, 4–30 cm long and 4–20 cm diameter, with a leathery rind surrounding segments or "liths" filled with pulp vesicles. The genus is commercially important as many species are cultivated for their fruit, which is eaten fresh, pressed for juice, or preserved in marmalades.
Citrus fruits are notable for their fragrance, partly due to flavonoids and limonoids (which in turn are terpenes) contained in the rind, and most are juice-laden. The juice contains a high quantity of citric acid giving them their characteristic sharp flavour. They are also good sources of vitamin C and flavonoids.
The pomelo (Citrus maxima or Citrus grandis) is a citrus fruit native to Southeast Asia. It is usually pale green to yellow when ripe, with sweet white (or, more rarely, pink or red) flesh and very thick pudgy rind. It is the largest citrus fruit, 15–25 cm in diameter, and usually weighing 1–2 kg. Other spellings for pomelo include pummelo, and pommelo, and other names include Chinese grapefruit, jabong, lusho fruit & pompelmous. The Chandler is a Californian variety of pomelo, with a smoother skin than many other varieties.
The pomelo tastes like a sweet, mild grapefruit, though the typical pomelo is much larger in size than the grapefruit. It has very little, or none, of the common grapefruit's bitterness.
Lime is a term referring to a number of different fruits, both species and hybrids, citruses, which are typically round, green to yellow in color, 3–6 cm in diameter, and containing sour and acidic pulp. Limes are often used to accent the flavours of foods and beverages.
Limes are a small citrus fruit, Citrus aurantifolia, whose skin and flesh are green in color and which have an oval or round shape with a diameter between one to two inches. Limes can either be sour or sweet, with the latter not readily available in the United States. Sour limes possess a greater sugar and citric acid content than lemons and feature an acidic and tart taste, while sweet limes lack citric acid content and are sweet in flavor.
In cooking, lime is valued both for the acidity of its juice and the floral aroma of its zest. It is a very common ingredient in authentic Mexican, Southwestern United States, Vietnamese and Thai dishes. It is also used for its pickling properties in ceviche. The use of dried limes (called black lime or loomi) as a flavouring is typical of Persian cuisine and Iraqi cuisine, as well as in Gulf-style baharat (a spice mixture that is also called kabsa or kebsa). Lime is an essential ingredient of any cuisine from India and many varieties of pickles are made e.g. Sweetened lime pickle, salted pickle, Lemon Chutney. Lime leaves are also a herb in South, East, and Southeast Asia.
In order to prevent scurvy during the 19th century, British sailors were issued a daily allowance of citrus such as lemon, and later switched to lime, which was not as effective at preventing scurvy but led over time to the nickname "limey" for all Britons. It was later discovered that the greater effectiveness of lemons derived from the 4-fold higher quantities of Vitamin C lemon juice contains compared to the West Indian limes used by the British.
In India, the lime is used in Tantra for removing evil spirits. It is also combined with Indian chilis to make a protective charm to repel the evil eye. Furthermore, it was believed that hanging limes over sick people cured them of the illness by repelling evil spirits lurking inside the body.
The grapefruit (Citrus × paradisi), is a subtropical citrus tree known for its bitter fruit, an 18th-century hybrid first bred in Barbados. When found it was named the "forbidden fruit"; it has also been misidentified with the pomelo or shaddock (C. maxima).
The fruit has become popular since the late 19th century; before that it was only grown as an ornamental plant. The United States quickly became a major producer of the fruit, with orchards in Florida, Texas, Arizona, and California. In Spanish, the fruit is known as toronja or pomelo.
Grapefruit is an excellent source of many nutrients and phytochemicals that contribute to a healthy diet. Grapefruit is a good source of vitamin C, contains the fiber pectin, and the pink and red hues contain the beneficial antioxidant lycopene. Studies have shown grapefruit helps lower cholesterol, and there is evidence that the seeds have antioxidant properties. Grapefruit forms a core part of the "grapefruit diet", the theory being that the fruit's low glycemic index is able to help the body's metabolism burn fat.
The Red grapefruit, starting with the Ruby Red, has even become a symbolic fruit of Texas, where white "inferior" grapefruit were eliminated and only red grapefruit were grown for decades. Using radiation to trigger mutations, new varieties were developed to retain the red tones which typically faded to pink, the Rio Red variety is the current (2007) Texas grapefruit with registered trademarks Rio Star and Ruby-Sweet, also sometimes promoted as "Reddest" and "Texas Choice".
Kumquats or cumquats are a group of small fruit-bearing trees in the flowering plant family Rutaceae, either forming the genus Fortunella, or placed within Citrus sensu lato. The edible fruit closely resembles that of the orange (Citrus sinensis), but is much smaller and ovular, being approximately the size and shape of an olive.
They have long been cultivated in Japan, Taiwan, the Philippines and southeast Asia. They were introduced to Europe in 1846 by Robert Fortune, collector for the London Horticultural Society, and shortly thereafter into North America.
Kumquats are often eaten raw. As the rind is sweet and the juicy centre is sour and salty, the raw fruit is usually consumed either whole—to savour the contrast—or only the rind is eaten. The fruit is considered ripe when it reaches a yellowish-orange stage and has just shed the last tint of green.
Culinary uses include candying and kumquat preserves, marmalade, and jelly. Kumquats can also be sliced and added to salads. In recent years kumquats have gained popularity as a garnish for cocktail beverages, including the martini as a replacement for the more familiar olive. A kumquat liqueur mixes the fruit with vodka or other clear spirit.