beta-cryptoxanthin),
flavonoid
Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans.
Chemically, flavonoids ...
s (e.g.
naringenin
Naringenin is a flavorless, colorless flavanone, a type of flavonoid. It is the predominant flavanone in grapefruit, and is found in a variety of fruits and herbs.
Structure
Naringenin has the skeleton structure of a flavanone with three hyd ...
) and numerous
volatile organic compounds
Volatile organic compounds (VOCs) are organic compounds that have a high vapour pressure at room temperature
Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a ...
producing orange
aroma
An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sense ...
, including
aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
s,
ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...
s,
terpene
Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ar ...
s,
alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
s, and
ketone
In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...
s.
![Saftpresse hg](https://upload.wikimedia.org/wikipedia/commons/4/4e/Saftpresse_hg.jpg)
Orange juice contains only about one-fifth the
citric acid
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in t ...
of
lime
Lime commonly refers to:
* Lime (fruit), a green citrus fruit
* Lime (material), inorganic materials containing calcium, usually calcium oxide or calcium hydroxide
* Lime (color), a color between yellow and green
Lime may also refer to:
Botany ...
or
lemon
The lemon (''Citrus limon'') is a species of small evergreen trees in the flowering plant family Rutaceae, native to Asia, primarily Northeast India (Assam), Northern Myanmar or China.
The tree's ellipsoidal yellow fruit is used for culin ...
juice (which contain about 47 g/L).
Grading
The
United States Department of Agriculture
The United States Department of Agriculture (USDA) is the United States federal executive departments, federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, ...
(USDA) has established the following grades for Florida oranges, which primarily apply to oranges sold as fresh fruit: US Fancy, US No. 1 Bright, US No. 1, US No. 1 Golden, US No. 1 Bronze, US No. 1 Russet, US No. 2 Bright, US No. 2, US No. 2 Russet, and US No. 3.
[United States Standards for Grades of Florida Oranges and Tangelos]
(USDA; February, 1997) The general characteristics graded are color (both hue and uniformity), firmness, maturity, varietal characteristics, texture, and shape. ''Fancy'', the highest grade, requires the highest grade of color and an absence of blemishes, while the terms ''Bright'', ''Golden'', ''Bronze'', and ''Russet'' concern solely discoloration.
Grade numbers are determined by the amount of unsightly blemishes on the skin and firmness of the fruit that do not affect consumer safety. The USDA separates blemishes into three categories:
# General blemishes: ammoniation, buckskin, caked melanose, creasing, decay, scab, split navels, sprayburn, undeveloped segments, unhealed segments, and wormy fruit
# Injuries to fruit: bruises, green spots, oil spots, rough, wide, or protruding navels, scale, scars,
skin breakdown
Pressure ulcers, also known as pressure sores, bed sores or pressure injuries, are localised damage to the skin and/or underlying tissue that usually occur over a bony prominence as a result of usually long-term pressure, or pressure in combi ...
, and thorn scratches
# Damage caused by dirt or other foreign material, disease, dryness, or mushy condition, hail, insects, riciness or woodiness, and sunburn.
The USDA uses a separate grading system for oranges used for juice because appearance and texture are irrelevant in this case. There are only two grades: US Grade AA Juice and US Grade A Juice, which are given to the oranges before processing. Juice grades are determined by three factors:
# The juiciness of the orange
# The amount of solids in the juice (at least 10% solids are required for the AA grade)
# The proportion of anhydric
citric acid
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in t ...
in fruit solids
Cultivation
Climate
![California Orange Grove2](https://upload.wikimedia.org/wikipedia/commons/d/d7/California_Orange_Grove2.jpg)
Like most citrus plants, oranges do well under moderate temperatures—between —and require considerable amounts of sunshine and water. It has been suggested the use of water resources by the citrus industry in the Middle East is a contributing factor to the
desiccation
Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container.
...
of the region. Another significant element in the full development of the fruit is the temperature variation between summer and winter and, between day and night. In cooler climates, oranges can be grown indoors.
As oranges are sensitive to
frost
Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above-freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase change from water vapor (a gas) ...
, there are different methods to prevent frost damage to crops and trees when subfreezing temperatures are expected. A common process is to spray the trees with water so as to cover them with a thin layer of ice that will stay just ''at'' the freezing point, insulating them even if air temperatures drop far lower. This is because water continues to lose heat as long as the environment is colder than it is, and so the water turning to ice in the environment cannot damage the trees. This practice, however, offers protection only for a very short time. Another procedure is burning fuel oil in
smudge pot
A smudge pot (also known as a choofa or orchard heater) is an oil-burning device used to prevent frost on fruit trees. Usually a smudge pot has a large round base with a chimney coming out of the middle of the base. The smudge pot is placed betwe ...
s put between the trees. These devices burn with a great deal of particulate emission, so condensation of water vapour on the particulate soot prevents condensation on plants and raises the air temperature very slightly. Smudge pots were developed for the first time after a disastrous freeze in Southern California in January 1913 destroyed a whole crop.
Propagation
It is possible to grow orange trees directly from seeds, but they may be infertile or produce fruit that may be different from its parent. For the seed of a commercial orange to grow, it must be kept moist at all times. One approach is placing the seeds between two sheets of damp paper towel until they germinate and then planting them, although many cultivators just set the seeds straight into the soil.
Commercially grown orange trees are
propagated asexually by
grafting
Grafting or graftage is a horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion () while the lower part is called the rootstock. The succ ...
a mature
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
onto a suitable
seedling
A seedling is a young sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle (embryonic root), the hypocotyl (embry ...
rootstock
A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced. It could also be described as a stem with a well developed root system, to which a bud from another plant is grafted. It can refer to a ...
to ensure the same
yield, identical fruit characteristics, and resistance to diseases throughout the years. Propagation involves two stages: first, a rootstock is grown from seed. Then, when it is approximately one year old, the leafy top is cut off and a bud taken from a specific
scion
Scion may refer to:
Arts, entertainment, and media Fictional entities
*Scion, a playable class in the game ''Path of Exile'' (2013)
*Atlantean Scion, a device in the ''Tomb Raider'' video game series
*Scions, an alien race in the video game ''Ba ...
variety, is grafted into its bark. The scion is what determines the variety of orange, while the rootstock makes the tree resistant to pests and diseases and adaptable to specific Soil type, soil and climatic conditions. Thus, rootstocks influence the rate of growth and have an effect on fruit yield and quality.
Rootstocks must be compatible with the variety inserted into them because otherwise, the tree may decline, be less productive, or die.
Among the several advantages to grafting are that trees mature uniformly and begin to bear fruit earlier than those reproduced by seeds (3 to 4 years in contrast with 6 to 7 years),
and that it makes it possible to combine the best attributes of a scion with those of a rootstock.
Harvest
Canopy-shaking mechanical harvesters are being used increasingly in Florida to harvest oranges. Current canopy shaker machines use a series of six-to-seven-foot-long tines to shake the tree canopy at a relatively constant stroke and frequency.
Normally, oranges are picked once they are pale orange.
Degreening
Oranges must be mature when harvested. In the United States, laws forbid harvesting immature fruit for human consumption in Texas, Arizona, California and Florida.
Ripe oranges, however, often have some green or yellow-green color in the skin. Ethylene gas is used to turn green skin to orange. This process is known as "degreening", also called "gassing", "sweating", or "curing".
Oranges are non-
climacteric fruits and cannot post-harvest ripen internally in response to ethylene gas, though they will de-green externally.
Storage
![2010-12-14 Maroc Agadir Soukh local market](https://upload.wikimedia.org/wikipedia/commons/b/b3/2010-12-14_Maroc_Agadir_Soukh_local_market.jpg)
Commercially, oranges can be stored by refrigeration in controlled-atmosphere chambers for up to twelve weeks after harvest. Storage life ultimately depends on cultivar, maturity, pre-harvest conditions, and handling. In stores and markets, however, oranges should be displayed on non-refrigerated shelves.
At home, oranges have a shelf life of about one month.
In either case, optimally, they are stored loosely in an open or perforated plastic bag.
Pests and diseases
Cottony cushion scale
The first major pest that attacked orange trees in the United States was the cottony cushion scale (''Icerya purchasi''), imported from Australia to California in 1868. Within 20 years, it wiped out the citrus orchards around Los Angeles, and limited orange growth throughout California. In 1888, the USDA sent Alfred Koebele to Australia to study this scale insect in its native habitat. He brought back with him specimens of ''Novius cardinalis'', an Australian Coccinellidae, ladybird beetle, and within a decade the pest was controlled.
Citrus greening disease
The Huanglongbing, citrus greening disease, caused by the bacterium ''Liberobacter asiaticum'', has been the most serious threat to orange production since 2010. It is characterized by streaks of different shades on the leaves, and deformed, poorly colored, unsavory fruit. In areas where the disease is endemic, citrus trees live for only five to eight years and never bear fruit suitable for consumption.
In the western hemisphere, the disease was discovered in Florida in 1998, where it has attacked nearly all the trees ever since. It was reported in Brazil by Fundecitrus Brasil in 2004.
[''Asian Citrus Psllids (Sternorryncha: Psyllidae) and Greening Disease of Citrus'', by Susan E. Halbert and Keremane L. Manjunath, Florida Entomologist (Abstract. September 2004) p. 33]
FCLA.edu
/ref> As from 2009, 0.87% of the trees in Brazil's main orange growing areas (São Paulo and Minas Gerais) showed symptoms of greening, an increase of 49% over 2008.[GAIN Report Number: BR9006]
, USDA Foreign Agricultural Service (June, 2009)
The disease is spread primarily by two species of psyllid insects. One of them is the Asian citrus psyllid (''Diaphorina citri'' Kuwayama), an efficient Vector (epidemiology), vector of the ''Liberobacter asiaticum''. Generalist and specialist species, Generalist predators such as the ladybird beetles ''Curinus coeruleus'', ''Olla v-nigrum'', ''Harmonia axyridis'', and ''Cycloneda sanguinea'', and the Neuroptera, lacewings ''Ceraeochrysa spp.'' and ''Chrysoperla spp.'' make significant contribution to the mortality of the Asian citrus psyllid, which results in 80–100% reduction in psyllid populations. In contrast, parasitism by ''Tamarixia radiata'', a species-specific parasitoid of the Asian citrus psyllid, is variable and generally low in southwest Florida: in 2006, it amounted to a reduction of less than 12% from May to September and 50% in November.
In 2007, foliar applications of insecticides reduced psyllid populations for a short time, but also suppressed the populations of predatory ladybird beetles. Soil application of aldicarb provided limited control of Asian citrus psyllid, while drenches of imidacloprid to young trees were effective for two months or more.
Management of citrus greening disease is difficult and requires an integrated approach that includes use of clean stock, elimination of inoculum via voluntary and regulatory means, use of pesticides to control psyllid vectors in the citrus crop, and biological control of psyllid vectors in non-crop reservoirs. Citrus greening disease is not under completely successful management.
Greasy spot
Greasy spot, a Fungal infection in plants, fungal disease caused by the ''Mycosphaerella citri'', produces leaf spots and premature defoliation, thus reducing the tree's vigour and yield. Ascospores of ''M. citri'' are generated in Ascocarp, pseudothecia in decomposing fallen leaves. Once mature, ascospores are ejected and subsequently dispersed by air currents.
Production
In 2020, world production of oranges was 75 million tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s, led by Brazil with 22% of the total, followed by India, China, the United States, and Mexico as other major producers (table).
In the United States, groves are located mainly in Florida, California, and Texas. The majority of California's crop is sold as fresh fruit, whereas Florida's oranges are destined to juice products. The Indian River (Florida), Indian River area of Florida is known for the high quality of its juice, which often is sold fresh in the United States and frequently blended with juice produced in other regions because Indian River trees yield very sweet oranges, but in relatively small quantities.
Orange juice is traded internationally as Juice#Preparation, frozen, concentrated orange juice to reduce the volume used so that storage and transportation costs are lower.
Products
Oranges, whose flavor may vary from sweet to sour, are commonly peeled and eaten fresh or squeezed for juice. The thick bitter rind is usually discarded, but can be processed into animal feed by desiccation
Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container.
...
, using pressure and heat. It also is used in certain recipes as a food flavoring or garnish (food), garnish. The outermost layer of the rind can be thinly grated with a zester to produce orange zest (ingredient), zest. Zest is popular in cooking because it contains oils and has a strong flavor similar to that of the orange pulp. The white part of the rind, including the pith, is a source of pectin and has nearly the same amount of vitamin C as the flesh and other nutrients.
Although not as juicy or tasty as the flesh, orange peel is edible and has significant contents of vitamin C, dietary fiber, total polyphenols, carotenoid
Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic compound, organic pigments that are produced by plants and algae, as well as several bacteria, and Fungus, fungi. Carotenoids give the characteristic color to pumpki ...
s, limonene and dietary minerals, such as potassium and magnesium.
Orange juice is obtained by squeezing the fruit on a special tool (a ''juicer'' or ''squeezer'') and collecting the juice in a tray underneath. This can be made at home or, on a much larger scale, industrially. Brazil is the largest producer of orange juice in the world, followed by the United States, where it is one of the commodities traded on the New York Board of Trade. Frozen orange juice concentrate is made from freshly squeezed and filtered orange juice.
Sweet orange oil is a by-product of the juice industry produced by pressing the peel. It is used for flavoring food and drinks and also in the perfume industry and aromatherapy for its fragrance. Sweet orange oil consists of approximately 90% limonene, D-limonene, a solvent used in various household chemicals, such as wood conditioners for furniture and—along with other citrus oils—detergents and hand cleansers. It is an efficient cleaning agent with a pleasant smell, promoted for being environmentally friendly and therefore, preferable to petrochemicals. D-limonene is, however, classified as irritating to the skin and as very toxic to aquatic life in different countries.
Marmalade preserves are traditionally made with Seville oranges, which are less sweet. All parts of the fruit are used: the pith and pips (separated and placed in a muslin bag) are boiled in a mixture of juice, slivered peel, sliced-up flesh, sugar, and water to extract their pectin, which helps the conserve to set.
See also
* Eliza Tibbets
Eliza Tibbets (born Eliza Maria Lovell; 1823–1898) was among early American settlers and founders of Riverside, California; she was an activist in Washington, D.C., for progressive social causes, including freedmen's rights and universal suffra ...
(for the history of orange groves in California, United States)
* List of citrus fruits
* List of culinary fruits
References
External links
*
*
''Citrus sinensis'' List of Chemicals (Dr. Duke's Phytochemical and Ethnobotanical Databases)
USDA, Agricultural Research Service.
Oranges: Safe Methods to Store, Preserve, and Enjoy
(2006). University of California Agriculture and Natural Resources. Accessed May 23, 2014.
{{Authority control
Oranges (fruit),
Articles containing video clips
Cocktail garnishes
Crops originating from China
Fruits originating in Asia
Symbols of California
Symbols of Florida
Tropical agriculture