Citrus

April 26th, 2007

Citrus is a common term and genus of flowering plants in the family Rutaceae, originating in tropical and subtropical southeast Asia. The plants are large shrubs or small trees, reaching 5â€“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 2â€“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, 4â€“30 cm long and 4â€“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 or pressed for juice.

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 taxonomy of the genus is complex and the precise number of natural species is unclear, as many of the named species are clonally-propagated hybrids, and there is genetic evidence that even the wild, true-breeding species are of hybrid origin. Cultivated Citrus may be derived from as few as four ancestral species. Numerous natural and cultivated origin hybrids include commercially important fruit such as the orange, grapefruit, lemon, some limes, and some tangerines. Recent research has suggested that the closely related genus Fortunella, and perhaps also Poncirus and the Australian genera Microcitrus and Eremocitrus, should be included in Citrus. In fact, most botanists now classify Microcitrus and Eremocitrus as part of the genus Citrus.

Cultivation

As citrus trees hybridise very readily (e.g., seeds grown from Persian limes can produce fruit similar to grapefruit), all commercial citrus cultivation uses trees produced by grafting the desired fruiting cultivars onto rootstocks selected for disease resistance and hardiness.

The color of citrus fruits only develops in climates with a (diurnal) cool winter. In tropical regions with no winter, citrus fruits remain green until maturity, hence the tropical “green orange”. The lime plant in particular is extremely sensitive to cool conditions, thus it is usually never exposed to cool enough conditions to develop a color. If they are left in a cool place over winter, the fruits will actually change to a yellow color. Many citrus fruits are picked while still green, and ripened while in transit to supermarkets.

Citrus fruitsCitrus trees are not generally frost hardy. Citrus reticulata tends to be the hardiest of the common Citrus species and can withstand short periods down to as cold as âˆ’10 Â°C, but realistically temperatures not falling below âˆ’2 Â°C are required for successful cultivation. A few hardy hybrids can withstand temperatures well below freezing, but do not produce quality fruit. A related plant, the Trifoliate orange (Poncirus trifoliata) can survive below âˆ’20 Â°C; its fruit are astringent and inedible unless cooked.

The trees do best in a consistently sunny, humid environment with fertile soil and adequate rainfall or irrigation. (Older ‘abandoned’ Citrus in low valleyland may suffer, yet survive, the dry summer of Central California Inner Coast Ranges. Any age Citrus grows well with infrequent irrigation in partial/understory shade, but the fruit crop is smaller.) Though broadleaved, they are evergreen and do not drop leaves except when stressed. The trees flower (sweet-scented at 2 to 20 meters) in the spring, and fruit is set shortly afterward. Fruit begins to ripen in fall or early winter months, depending on cultivar, and develops increasing sweetness afterward. Some cultivars of tangerines ripen by winter. Some, such as the grapefruit, may take up to eighteen months to ripen.

Limes in a grocery store.Major commercial citrus growing areas include southern China and most part of Asia, the Mediterranean Basin (including Southern Spain), South Africa, Australia, the southernmost United States, and parts of South America. In the U.S., Florida, Texas, and California are major producers, while smaller plantings are present in other Sun Belt states.

Common Uses
Lemonade or limeade are popular beverages prepared by diluting the juices of these fruits and adding sugar. Lemons and limes are also used as garnishes or in cooked dishes. Their juice is used as an ingredient in a variety of dishes, it can commonly be found in salad dressings and squeezed over cooked meat or vegetables. A variety of flavours can be derived from different parts and treatments of citrus fruits. The rind and oil of the fruit is generally very bitter, especially when cooked. The fruit pulp can vary from sweet and tart to extremely sour. Marmalade, a condiment derived from cooked orange and lemon, can be especially bitter. Lemon or lime is commonly used as a garnish for water, soft drinks, or cocktails. Citrus juices, rinds, or slices are used in a variety of mixed drinks. The skin of some citrus fruits, known as zest, is used as a spice in cooking. The zest of a lemon can also be soaked in water in a coffee filter, and drank.Lemon-Tea is a very good and testful drink for many Asians.

Kaffir Lime Leaves:
Aroma and Flavour: The haunting bouquet is unmistakably citrus and scented. The full citrus flavour is imparted when the leaves are torn or shredded.

Culinary Use: Apart from the leaves of the bush , only the fruit rind is used, finely grated, in Thai and Indonesian dishes. The leaves are torn or finely shredded and used in soups and curries - they also give a distinctive flaour to fish and chicken dishes.

Medical Uses:

The citrus juice used to be included in Thai ointments and shampoo, and in tonics in Malaysia.
Citrus juice also has medical uses - the lemon juice is used to relieve the pain of bee stings. The orange is also used in Vitamin C pills, which prevents scurvy. Scurvy is caused by Vitamin C deficiency, and can be prevented by having 10 milligrams of Vitamin C a day. An early sign of scurvy is fatigue. If ignored, later symptoms are bleeding and brusing easily.

A native from Asia, probably from India, it is now widely cultivated in Italy, California and Australia. Lemon was unknown to the ancient Greeks arriving in Europe probably brought by Roman soldiers returning from Asia Minor. It is one of the most important and versatile natural medicines for home use. A familiar food as well as a remedy, it has a high vitamin C content that helps improve resistance to infection, making it valuable for colds and flu. It is taken as a preventative for many conditions, including stomach infections, circulatory problems and arteriosclerosis. Lemon juice and oil are effective in killing germs. It decreases inflammation and improves digestion.

MAIN PROPERTIES: Antiseptic, anti-rheumatic, antibacterial, antioxidant, reduces fever.

Source:en.wikipedia.org