Orange trees is a redirect to this article. For the 1878 painting by French painter Gustave Caillebotte, see The Orange Trees.
The orange (pronunciation: [oˈʁaŋʒə] or [oˈʁɑ̃ːʒə]), also called the apfelsine (from Low German appelsina, literally “apple from China/Sina”) north of the Speyer line, is an evergreen tree; specifically, its fruit is so named. The valid botanical name of the orange is Citrus × sinensis L., thus it belongs to the genus of citrus plants (Citrus) in the rue family (Rutaceae). It originated in China or Southeast Asia, where it was created from a cross between mandarin (Citrus reticulata) and grapefruit (Citrus maxima).
The bitter orange, which originated from the same parent species, is distinguished from the sweet oranges because of their entirely different uses. While the bitter orange arrived in Italy no later than the 11th century, the sweet variety was not introduced to Europe until the 15th century, where it was initially grown almost exclusively in Portugal. The sweet orange is the most widely cultivated citrus fruit in the world.
Orange trees are small to medium sized evergreen trees with growth heights up to 10 meters. The round crown of the tree has regular branching. The young twigs are angular and covered with thin, flexible, rather blunt thorns up to 8 cm long.
The alternate and spirally arranged (unifoliate) leaves are divided into petiole and leaf blade. The petiole is obovate, only slightly broadened (winged), with a narrow base, 1 to 3 cm wide and 0.6 to 1.5 cm long. The leathery, thick, dark green leaf blade is clearly separated from the petiole, with a rounded leaf base, oval and acuminate.
The cotyledons are milky white.
Flowers are solitary in leaf axils or clustered together in few-flowered, racemose inflorescences. The fragrant flowers are radially symmetrical and hermaphroditic or purely male with a double perianth. The four or five sepals are fused. The five free petals are white in color. There are 20 to 25 stamens, the filaments of which are fused into several groups at their bases. The ovary is oval and clearly separated from the pistil. In Europe, the orange blooms from February to June, in China from April to May.
Orange trees, like many other citrus fruits, develop fruit without cross-pollination. In the fruit (Hesperidium), the sarcocarp consists of ten to thirteen segments filled with sap tubes of mostly orange, occasionally yellow to red color. Each segment is surrounded by a thin cuticle (endocarp), and the entire fruit is surrounded by a bipartite shell. The inner layer of the peel is white (mesocarp, albedo), and the outer is orange or green when ripe (exocarp, flavedo). Numerous oil glands are located in the ripe fruit skin; they emit an aromatic fragrance. The peel and segments are fused together, and the fruit is more difficult to peel or divide than other citrus fruits. The central axis of the fruit is not hollow, unlike the bitter orange. Each fruit contains many seeds. The large, oval seeds have a rough seed coat and a white interior. Each seed contains one to usually many embryos of varying sizes. In China, the fruits ripen from September to December.
The basic chromosome number is n = 9. Polyploid forms occur in addition to diploid forms.
Fruit color and quality
In regions with tropical warm nights and high humidity, the fruits remain green during ripening. Thus, the color orange is not a ripening characteristic. Since many consumers consider the green color to be an unripeness characteristic, the green fruits are usually degreened before sale by exposing them to ethylene gas, which destroys the green chlorophyll in the skin. Any resulting loss of quality is accepted for the sake of better marketing.
The EU marketing standard for citrus fruits stipulates that the coloration of oranges must be typical of the variety. A maximum of one fifth of the peel may be light green in color. However, oranges produced in areas where air temperatures and relative humidity are high during the development period may have more than one-fifth of the peel colored green. (In addition, all oranges must have a minimum juice content of 30% to 45%, depending on the variety). Degreening is permitted in the EU.
The name orange (Latin formerly Aurantia resp. Citrus aurantium) derives via Old Provençal auranja and Spanish naranja from Arabic (nārandsch / نارنج), which in turn derives via Persian (nārendsch / نارنج / nāranğ, and nāreng / نارنگ) and Sanskrit ञरंगः nāranga from a Dravidian word (cf. Tamil nāram). The n- was replaced by other anlaut consonants when borrowed from Spanish into other Romance languages (Portuguese laranja, Catalan taronja) and was eventually lost altogether (French orange; Provençal irange; Italian: arancia). In Arabic, orange is now called burtuqāl / برتقال (from “Portugal”), while nārandsch / نارنج stands for bitter orange. Similarly, in Modern Greek, the bitter νεράντζι nerantsi is distinguished from the sweet πορτοκάλι portokali. The color orange is named after the fruit.
The name orange is derived from apple-sine, Chinese apple (cf. Dutch sinaasappel “China’s apple”). Until the middle of the 20th century, there was still a clear division in linguistic usage – north of the Main River, in the Rhine Palatinate and in eastern Germany, the fruit was called “Apfelsine”. In the meantime, the leading form “orange” is increasingly gaining acceptance, presumably because this name sounds “finer”. The large northern German fruit juice producer riha says it uses the name “orange juice” when the juice contains fruit pulp.
The orange cannot be traced in Europe before the 15th century – in contrast to the similar bitter orange, which had already reached Europe by land in the Middle Ages. Although individual references to sweet oranges exist for an earlier date, the quality seems to have increased considerably only from 1500 onwards, due to the introduction of better varieties by Portuguese, who spread them in Europe after the discovery of the sea route to India. For example, Vasco da Gama reported in 1498 that he had seen very good oranges in Mombasa, much better than those known in Portugal at that time. The association of sweet oranges and Portugal, which has been reflected in the naming in several languages, was possibly promoted by the tale that the one, original and originally imported tree still stood in Lisbon for centuries.
In Europe, oranges are harvested from August (early varieties from Seville) to May (late variety Tardivo di Sanvito, Sardinia). The most important orange product in world trade is orange juice, most of which comes from Brazil and is traded in the form of concentrate (syrup). Fresh oranges have also become firmly established in the food landscape of numerous countries. In the past as protection, today for advertising purposes, oranges are often offered for sale wrapped in orange paper.
In addition, the orange also serves as a source of fragrance: The terpene d-limonene is extracted from orange peels and has many uses as a biogenic solvent and raw material for the perfume industry. The noble-smelling neroli oil is obtained by steam distillation of orange blossoms, although it is usually not the blossoms of Citrus sinensis but those of the bitter orange (Citrus × aurantium) that are used.
Wafer-thin, bitter substance-free orange peels, as they are needed for flavoring many dishes, can be produced with a zester (sometimes also called zesteur). Dried orange peels are also often found in tea blends. The blossoms can also be made into a tea.
Orange slices, blossoms and peels are also used to decorate food and drinks (orange twist).
Different varieties of oranges: “Navels” (yellow), origin South Africa and “Valencia Late” (orange), origin Spain.
Orange varieties are divided into bitter oranges (Pomeranzen) and four groups of sweet orange varieties, the blond oranges (also: round oranges), the navel oranges (also: navel oranges), the pigmented oranges (blood and half blood oranges) and the non-acid oranges.
Blond oranges (most important group)
- ‘Shamouti’ (also ‘Jaffa orange’), grown mainly in Israel.
- Valencia’ or also called ‘Valencia Late’, mainly grown in the Mediterranean region, South Africa and the U.S.
- Hart’s Tardiff
Navel oranges (originally native to Brazil), also called Bahia oranges. Their characteristic is a protuberance at the flower pole, where – starting from another, smaller circle of carpels – a second, usually underdeveloped daughter fruit has formed.
- ‘Washington NewHal’, recognizable by the large protuberances at the apex and often huge fruit size, usually declared as Navelina
- ‘Cara Cara’, a selection of ‘Bahia’ with red flesh (usually declared as Washington Sanguine), originating in California and from Spain, often confused with blood oranges
- ‘Navelina’, a Spanish selection in all fruit sizes with almost no daughter fruit.
- ‘Salustiana’, small caliber fruit with thin skin, best for pressing
- ‘Navelate’, a late ripening Spanish selection, very sweet.
- ‘NavelLaneLate’, before ‘Valencia Late’ the latest of the Navel oranges
- ‘Powell Navel’, a late ripening very sweet orange
Blood oranges (because of the deep red flesh, and in some varieties also because of the peel). The red flesh coloration is caused by anthocyanin in the pigments of the flesh and peel and occurs in dry areas with large daily temperature differences (night frosts). Moro oranges, for example, grow on the slopes of the Etna volcano in Sicily.
- ‘Sanguine’ (round blood)
- ‘Double fine’ (blood oval)
- La Maltaise Sanguine
- Often mistakenly called acid-free oranges (native to India and elsewhere), these citrus fruits are early-ripening green-skinned, sometimes yellow-skinned sweet limes (Citrus Limetta) that are sweeter but less aromatic due to their low acidity. Harvest this variety in late fall to winter.
Fruit body / fruit juice
The content of phytonutrients in 100 g of fruit pulp from sweet oranges is approx.
19.36 mg ± 0.10 mg vitamin C (ascorbic acid) (the recommended daily requirement of vitamin C is 80 mg according to Annex XIII of the Food Information Regulation (LMIV))
- 0.06 mg ± 0.20 mg vitamin B1 (thiamine)
- 0.11 mg ± 0.20 mg vitamin B2 (riboflavin)
- 0.38 mg ± 0.10 mg nicotinic acid (niacin)
- 0.62 mg ± 0.10 mg Alkaloids
- 0.19 mg ± 0.20 mg flavonoids
- 0.04 mg ± 0.11 mg tannins
- 0.01 mg ± 0.10 mg phenols
- 0.08 mg ± 0.10 mg saponins
Important natural flavoring substances in orange juice are, for example, acetaldehyde, hexanal, octanal, nonanal, decanal, ethyl 2-methylbutyrate, (R)-limonene, myrcene, and (R)-α-pinene. At the same time, the composition of the flavors varies to some extent depending on the orange variety. This applies, for example, to ethyl acetate, ethyl propanoate, (S)-linalool, ethyl 2-methylpropanoate, 1-penten-3-one, ethyl butanoate, 3-isopropyl-2-methoxy-pyrazine, (R)-methyl-3-hydroxyhexanoate and 2- and 3-methylbutyric acid. Many of the esters are only found in orange juice, but not in orange peel oil
After dehydration, both fiber and antioxidants can be altered in quality and quantity, depending on the duration or temperature (30 °C versus 90 °C) of air drying.
The peel contains 0.3 to 0.5% orange oil (main constituent limonene), which is used for flavoring, medicinal, cosmetic and technical purposes. Orange oil is a hazardous substance, harms the respiratory tract, is flammable, irritates the skin and eyes, and is harmful to aquatic organisms. The surface of oranges is often treated with waxes to protect against mold, and preservatives such as thiabendazole (E 233), orthophenylphenol (E 231), sodium orthophenylphenol (E 232), biphenyl (E 230, no longer allowed in the EU), and imazalil are usually added to these waxes (except in organic farming).
Sweet orange seeds, peeled or unpeeled, in one analysis contained about 54.2% fats, 28.5% carbohydrates, 5.5% fiber, 3.1% protein, and 2.5% ash (minerals) in the unpeeled seeds, each on a dry matter basis. Among the minerals, calcium and potassium dominated.