Citrus

Names

Scientific Name

Citrus spp.

Common Names

English: Lemon, Orange, Mandarin, Sweet lime; German: Zitrone, Apfelsine, Mandarine, Limette; French: Citron, Orange, Mandarine, Limette; Spanish: Limon, Naranja, Mandarina, Lima

Taxonomy

Family

Rutaceae.
The taxonomy of the genus Citrus, which belongs to the Rue family (Rutaceae), is very controversial. Not only are the common names for the various fruits used inconsistently (e.g. tangerines are considered as a synonym for mandarins by some authors, and as a group comprising mandarins, satsumas etc. by others), but whether they represent different species or just varieties is almost impossible to decide. They all hybridise easily – a fact that has been utilised by growers for probably thousands of years.

Occurrence

Agriculture Importance

Citrus fruits are the most valuable fruit crop in international trade.

Cultivation Areas

All of the numerous Citrus varieties are cultivated in subtropical or tropical regions. They originate from different parts of the world. Oranges were already being used in China in 2000 BC, while the Seville orange (also known as the bitter or sour orange) was first grown in northern India. The lemon comes from the eastern Himalayas; mandarins, however, probably derive from the Mediterranean.
Today, citrus is cultivated in 140 countries; about 70% of fruits are produced in the northern hemisphere. Lemons, for example, are grown in Southern and Central America, Asia, around the Mediterranean and in parts of the USA, the most significant producers being Europe and Argentina. Under favorable conditions, three harvests per year are possible. Mandarins and kumquats are comparatively hardy and are therefore often cultivated in more northerly areas such as China.
More than two-thirds of global citrus production is done in Brazil, USA, China, Mexico and Spain. In Brazil and the USA, about 70% of the harvest is used for processing, whereas the Mediterranean countries produce mostly for fresh consumption, supplying primarily the European market. In Asia, most of the citrus produced is consumed domestically.

Special Information

Citrus plants are typically evergreen shrubs or small- to medium-sized trees. They are heavily pruned during cultivation, and therefore do not reach their natural height.
Flowers are usually white and often fragrant. Many species bear spherical fruits with a green, yellow, or orange peel containing numerous oil glands. Another common characteristic of this genus are leaf thorns and feathered leaf stalks.
Individual trees of some species may live for up to 100 years.
Citrus fruits can make an important contribution to human nutrition, because they are a prominent source of vitamin C (L-ascorbic acid). The flesh of a lemon provides up to ~50 mg vitamin C per 100g. In the human body, ascorbic acid serves as a reducing agent, e.g. in hydroxylation during collagen synthesis, tyrosine degradation, catecholamine synthesis and the biosynthesis of bile. Vitamin C deficiency causes the disease scurvy, which leads to damage to connective tissues, internal bleeding, tooth loss, fever and eventually, death.
The economically most important varieties are lemon (Citrus limon), orange (Citrus sinensis), mandarin (Citrus reticulata, C. deliciosa), grapefruit (Citrus x paradisi), lime (Citrus aurantiifolia), Seville orange (Citrus aurantium), pummelo (Citrus maxima), citron (Citrus medica) and kumquat (Fortunella margarita/ Citrus margarita).

Use

Food

About one third of worldwide Citrus production is not used for fresh consumption, but rather for processing, primarily for making juice. About 80% of it is from oranges, and is consumed for the most part directly; the juice of the sour varieties in particular is also used as a natural souring agent in soft drinks, preserves and processed food. Citrus peel is used for flavoring. The candied rind of citrons and sour oranges is a traditional ingredient of baked goods (e.g. christmas cakes) in many countries. Marmalade from oranges or lemons is very popular in some regions, too. The annual world production of citrus fruits exceeds 70 million (metric) tons (data from 2007/2008), broken down as follows:

oranges: for fresh consumption 23 million tons
oranges: for processing 22 million tons, about 85% from Florida (USA) and Brazil
mandarins: 16 million tons
grapefruits: 5 million tons
lemons: 4 million tons
others (limes, sour oranges etc.): 2 million tons

Industrial Products

The oils from Citrus peel are used in cosmetics as a fragrance, and also in household detergents, as an active ingredient. Technical applications include use as a thinner, solvent and cleaning agent.

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