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89-455: The grapefruit ( Citrus × paradisi ) is a subtropical citrus tree known for its relatively large, sour to semi-sweet, somewhat bitter fruit. The flesh of the fruit is segmented and varies in color from pale yellow to dark red. Grapefruit is a citrus hybrid that originated in Barbados in the 18th century. It is an accidental cross between the sweet orange ( C. × sinensis ) and

178-656: A sugar nip , a pliers-like tool, in order to break off pieces. The demand for cheaper table sugar drove, in part, colonization of tropical islands and nations where labor-intensive sugarcane plantations and table sugar manufacturing could thrive. Growing sugar cane crop in hot humid climates, and producing table sugar in high temperature sugar mills was harsh, inhumane work. The demand for cheap labor for this work, in part, first drove slave trade from Africa (in particular West Africa), followed by indentured labor trade from South Asia (in particular India). Millions of slaves, followed by millions of indentured laborers were brought into

267-404: A black, carbon -rich solid, as indicated in the following idealized equation: H 2 SO 4 (catalyst) + C 12 H 22 O 11 → 12 C + 11 H 2 O + heat (and some H 2 O + SO 3 as a result of the heat) . The formula for sucrose's decomposition can be represented as a two-step reaction: the first simplified reaction is dehydration of sucrose to pure carbon and water, and then carbon

356-458: A high quantity of citric acid , which with other organic acids including ascorbic acid (vitamin C) give them their characteristic sharp taste. Citrus fruits are diverse in size and shape, as well as in color and flavor, reflecting their biochemistry; for instance, grapefruit is made bitter-tasting by a flavanone, naringin . Most commercial citrus cultivation uses trees produced by grafting

445-576: A linear furanocoumarin derived from psoralen . This claim has been confirmed for lime and bergamot . In particular, bergamot essential oil has a higher concentration of bergapten (3–3.6 g/kg) than any other Citrus -based essential oil. A systematic review indicates that citrus fruit consumption is associated with a 10% reduction of risk for developing breast cancer. Many citrus fruits, such as oranges , tangerines , grapefruits , and clementines , are generally eaten fresh. They are typically peeled and can be easily split into segments. Grapefruit

534-716: A natural hybrid. One ancestor of the grapefruit was the Jamaican sweet orange ( Citrus sinensis ), itself an ancient hybrid of Asian origin; the other was the Indonesian pomelo ( C. maxima ). The pomelo was the female ancestor; the sweet orange, itself a hybrid, was the male. Both C. sinensis and C. maxima were present in the West Indies by 1692. One story of the fruit's origin is that a 17th-century trader named 'Captain Shaddock' brought pomelo seeds to Jamaica and bred

623-454: A plant distinct from grapefruit although still closely related to it. In 1814, the British naturalist and plantation owner John Lunan published the term grapefruit to describe a similar Jamaican citrus plant. Lunan reported that the name was due to its similarity in taste to the grape ( Vitis vinifera ). An alternative explanation is that this name may allude to clusters of the fruit on

712-491: A small number of core ancestral species, including the citron, pomelo, and mandarin. Natural and cultivated citrus hybrids include commercially important fruit such as oranges, grapefruit , lemons, limes, and some tangerines . The multiple hybridisations have made the taxonomy of Citrus complex. Apart from these core species, Australian limes and the recently discovered mangshanyegan are grown. Kumquats and Clymenia spp. are now generally considered to belong within

801-572: A sticky, extracellular, dextran -based polysaccharide that allows them to cohere, forming plaque . Sucrose is the only sugar that bacteria can use to form this sticky polysaccharide. The word sucrose was coined in 1857, by the English chemist William Miller from the French sucre ("sugar") and the generic chemical suffix for sugars -ose . The abbreviated term Suc is often used for sucrose in scientific literature. The name saccharose

890-460: A wasp on one of the fruits. The impressionist Edouard Manet depicted a lemon on a pewter plate. In modern art, Arshile Gorky painted Still Life with Lemons in the 1930s. Citrus fruits "were the clear status symbols of the nobility in the ancient Mediterranean", according to the paleoethnobotanist Dafna Langgut. In Louisa May Alcott 's 1868 novel Little Women , the character Amy March states that "It's nothing but limes now, for everyone

979-460: A wide range of appearance and fruit flavors. The large citrus fruit of today evolved originally from small, edible berries over millions of years. Citrus species began to diverge from a common ancestor about 15 million years ago, at about the same time that Severinia (such as the Chinese box orange ) diverged from the same ancestor. About 7 million years ago, the ancestors of Citrus split into

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1068-485: Is a genus of flowering trees and shrubs in the family Rutaceae . Plants in the genus produce citrus fruits , including important crops such as oranges , mandarins , lemons , grapefruits , pomelos , and limes . Citrus is native to South Asia, East Asia, Southeast Asia, Melanesia , and Australia. Indigenous people in these areas have used and domesticated various species since ancient times. Its cultivation first spread into Micronesia and Polynesia through

1157-435: Is a mutation-bred variety that was developed by treatment of bud sticks with thermal neutrons. Its improved attributes of mutant variety are fruit and juice color, deeper red, and wide adaptation. The 'Star Ruby' is the darkest of the red varieties. Developed from an irradiated 'Hudson' grapefruit ('Hudson' being a limb sport of 'Foster', itself a limb sport of the 'Walters'), it has found limited commercial success because it

1246-468: Is a naturally occurring sugar, but with the advent of industrialization , it has been increasingly refined and consumed in all kinds of processed foods. The production of table sugar has a long history. Some scholars claim Indians discovered how to crystallize sugar during the Gupta dynasty , around CE 350. Other scholars point to the ancient manuscripts of China, dated to the 8th century BCE, where one of

1335-430: Is by isotope analysis of carbon. Cane uses C4 carbon fixation , and beet uses C3 carbon fixation , resulting in a different ratio of C and C isotopes in the sucrose. Tests are used to detect fraudulent abuse of European Union subsidies or to aid in the detection of adulterated fruit juice . Sugar cane tolerates hot climates better, but the production of sugar cane needs approximately four times as much water as

1424-452: Is grown – crush the cane and produce raw sugar which is shipped to other factories for refining into pure sucrose. Sugar beet factories are located in temperate climates where the beet is grown, and process the beets directly into refined sugar. The sugar-refining process involves washing the raw sugar crystals before dissolving them into a sugar syrup which is filtered and then passed over carbon to remove any residual colour. The sugar syrup

1513-477: Is more commonly halved and eaten out of the skin with a spoon. Lemonade is a popular beverage prepared by diluting the juice and adding sugar. Lemon juice is mixed in salad dressings and squeezed over fruit salad to stop it from turning brown: its acidity suppresses oxidation by polyphenol oxidase enzymes. A variety of flavours can be derived from different parts and treatments of citrus fruits. The colourful outer skin of some citrus fruits, known as zest ,

1602-603: Is more difficult to grow than other varieties. Raw white grapefruit is 90% water, 8% carbohydrates, 1% protein, and contains negligible fat (table). In a reference amount of 100 grams ( 3 + 1 ⁄ 2 ounces), raw grapefruit provides 138 kilojoules (33 kilocalories) of food energy and is a rich source of vitamin C (37% of the Daily Value ), with no other micronutrients in significant amounts (table). Like other citrus fruits, grapefruits are sour because of their citric acid content; grapefruit juice contains about half

1691-443: Is often used in food preparation, humans find molasses from sugar beets unpalatable, and it consequently ends up mostly as industrial fermentation feedstock (for example in alcohol distilleries), or as animal feed . Once dried, either type of molasses can serve as fuel for burning. Pure beet sugar is difficult to find, so labelled, in the marketplace. Although some makers label their product clearly as "pure cane sugar", beet sugar

1780-609: Is oxidised to CO 2 by O 2 from air. C 12 H 22 O 11 + heat → 12 C + 11 H 2 O 12 C + 12 O 2 → 12 CO 2 Hydrolysis breaks the glycosidic bond converting sucrose into glucose and fructose . Hydrolysis is, however, so slow that solutions of sucrose can sit for years with negligible change. If the enzyme sucrase is added, however, the reaction will proceed rapidly. Hydrolysis can also be accelerated with acids, such as cream of tartar or lemon juice, both weak acids. Likewise, gastric acidity converts sucrose to glucose and fructose during digestion,

1869-451: Is sucking them in their desks in schooltime, and trading them off for pencils, bead rings, paper dolls, or something else… If one girl likes another, she gives her a lime; if she’s mad with her, she eats one before her face, and doesn’t offer even a suck." Sucrose For human consumption, sucrose is extracted and refined from either sugarcane or sugar beet . Sugar mills – typically located in tropical regions near where sugarcane

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1958-458: Is that grapefruit compounds may inhibit the absorption of drugs in the intestine. If a drug is not absorbed, then not enough of it is in the blood to have a therapeutic effect. Each affected drug has either a specific increase of effect or decrease. One whole grapefruit or a glass of 200 ml (7 US fl oz) of grapefruit juice may cause drug overdose toxicity. Typically, drugs that are incompatible with grapefruit are marked as such on

2047-500: Is the main sugar. In others, such as grapes and pears , fructose is the main sugar. After numerous unsuccessful attempts by others, Raymond Lemieux and George Huber succeeded in synthesizing sucrose from acetylated glucose and fructose in 1953. In nature, sucrose is present in many plants, and in particular their roots, fruits and nectars , because it serves as a way to store energy, primarily from photosynthesis . Many mammals, birds, insects and bacteria accumulate and feed on

2136-594: Is the source of the word candy . The army of Alexander the Great was halted on the banks of river Indus by the refusal of his troops to go further east. They saw people in the Indian subcontinent growing sugarcane and making "granulated, salt-like sweet powder", locally called sākhar ( साखर ), ( شکر ), pronounced as sakcharon ( ζακχαρον ) in Greek (Modern Greek, zachari , ζάχαρη ). On their return journey,

2225-439: Is then concentrated by boiling under a vacuum and crystallized as the final purification process to produce crystals of pure sucrose that are clear, odorless, and sweet. Sugar is often an added ingredient in food production and recipes. About 185 million tonnes of sugar were produced worldwide in 2017. Sucrose is particularly dangerous as a risk factor for tooth decay because Streptococcus mutans bacteria convert it into

2314-580: Is used as a flavouring in cooking. The whole of the bitter orange (and sometimes other citrus fruits) including the peel with its essential oils is cooked with sugar to make marmalade . By the 17th century, orangeries were added to great houses in Europe, both to enable the fruit to be grown locally and for prestige, as seen in the Versailles Orangerie . Some modern hobbyists grow dwarf citrus in containers or greenhouses in areas where

2403-453: Is used in some recipes for fish. Grapefruit and grapefruit juice interact with numerous drugs, resulting in numerous adverse effects . Effects commonly include abnormal heart rhythms, bleeding inside the stomach, low blood pressure, difficulty breathing, and dizziness. One interaction occurs from grapefruit furanocoumarins , such as bergamottin and 6',7'-dihydroxybergamottin , which occur in both flesh and peel. Furanocoumarins inhibit

2492-698: Is yellow-orange skinned and generally an oblate spheroid in shape; it ranges in diameter from 10 to 15 cm (4 to 6 in). Its flesh is segmented and acidic, varying in color depending on the cultivars , which include white, pink, and red pulps of varying sweetness (generally, the redder varieties are the sweetest). The 1929 U.S. 'Ruby Red' (of the 'Redblush' variety) was the first grapefruit patent . The varieties of Texas and Florida grapefruit include: 'Duncan', 'Flame', 'Henderson', 'Hudson', 'Marsh', 'Oro Blanco', 'Pink', 'Pummelo HB', 'Ray', 'Rio Star', 'Ruby Red', 'Star Ruby', 'Thompson', 'Triumph', 'Walters', 'White Marsh'. The 1929 'Ruby Red' (or 'Redblush') patent

2581-698: The Austronesian expansion ( c.  3000 –1500 BCE). Later, it was spread to the Middle East and the Mediterranean ( c.  1200 BCE ) via the incense trade route , and from Europe to the Americas. Renowned for their highly fragrant aromas and complex flavor, citrus are among the most popular fruits in cultivation. With a propensity to hybridize between species, making their taxonomy complicated, there are numerous varieties encompassing

2670-623: The CYP3A4 enzyme (among others from the P450 enzyme family responsible for metabolizing 90% of drugs). The action of the CYP3A4 enzyme itself is to metabolize many medications. If a drug's breakdown for removal is lessened, then the level of that drug in the blood may become and remain high, leading to adverse effects. On the other hand, some drugs must be metabolized to become active, and inhibiting CYP3A4 may lead to reduced drug effects. Another effect

2759-740: The Philippines . This was followed by the spread of citrus species into Taiwan and Japan in the Early Pliocene (5.33 to 3.6 mya ), resulting in the tachibana orange ( C. tachibana ); and beyond the Wallace Line into Papua New Guinea and Australia during the Early Pleistocene (2.5 million to 800,000 years ago), where further speciation events created in the Australian limes . A fossil leaf from

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2848-640: The Pliocene of Valdarno , Italy is described as † Citrus meletensis . In China, fossil leaf specimens of † Citrus linczangensis have been collected from late Miocene coal-bearing strata of the Bangmai Formation in Yunnan province. C. linczangensis resembles C. meletensis in having an intramarginal vein, an entire margin, and an articulated and distinctly winged petiole . Many cultivated Citrus species are natural or artificial hybrids of

2937-638: The West Indies in 1506 ( Cuba in 1523). The Portuguese first cultivated sugarcane in Brazil in 1532. Sugar remained a luxury in much of the world until the 18th century. Only the wealthy could afford it. In the 18th century, the demand for table sugar boomed in Europe and by the 19th century it had become regarded as a human necessity. The use of sugar grew from use in tea, to cakes , confectionery and chocolates . Suppliers marketed sugar in novel forms, such as solid cones, which required consumers to use

3026-665: The citron ( C. medica ) or a conifer tree ( Thuja ). The Latin word is related to the ancient Greek word for the cedar of Lebanon , κέδρος ( kédros ), perhaps from a perceived similarity of the smell of citrus leaves and fruit with that of cedar. Citrus plants are large shrubs or small to moderate-sized trees, reaching 5–15 m (16–49 ft) 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 (0.79–1.57 in) diameter, with five (rarely four) white petals and numerous stamens; they are often very strongly scented, due to

3115-421: The citrons ( Citrus medica ) of South Asia; the pomelos ( C. maxima ) of Mainland Southeast Asia ; the mandarins ( C. reticulata ), kumquats ( C. japonica ), mangshanyegan ( C. mangshanensis ), and ichang papedas ( C. cavaleriei ) of southeastern China; the kaffir limes ( C. hystrix ) of Island Southeast Asia ; and the biasong and samuyao ( C. micrantha ) of

3204-463: The date palm ( Phoenix dactylifera ), sorghum ( Sorghum vulgare ), and the sugar maple ( Acer saccharum ). Sucrose is obtained by extraction of these crops with hot water; concentration of the extract gives syrups, from which solid sucrose can be crystallized. In 2017, worldwide production of table sugar amounted to 185 million tonnes. Most cane sugar comes from countries with warm climates, because sugarcane does not tolerate frost. Sugar beets, on

3293-416: The pomelo ( C. maxima ), both of which were introduced from Asia in the 17th century. It has also been called the ' forbidden fruit '. In the past it was called the pomelo , but that term is now mostly used as the common name for Citrus maxima . Grapefruit–drug interactions are common, as the juice contains furanocoumarins that interfere with the metabolism of many drugs. This can prolong and intensify

3382-487: The water-gas shift reaction also take place. A more accurate theoretical equation is: C 12 H 22 O 11 + 6.288 KNO 3 → 3.796 CO 2 + 5.205 CO + 7.794 H 2 O + 3.065 H 2 + 3.143 N 2 + 2.988 K 2 CO 3 + 0.274 KOH Sucrose burns with chloric acid , formed by the reaction of hydrochloric acid and potassium chlorate : 8 HClO 3 + C 12 H 22 O 11 → 11 H 2 O + 12 CO 2 + 8 HCl Sucrose can be dehydrated with sulfuric acid to form

3471-552: The 1940s, at which point its official name was altered to Citrus × paradisi , the × identifying it as a hybrid. An early pioneer in the American citrus industry was Kimball C. Atwood, a wealthy entrepreneur who founded the Atwood Grapefruit Company in the late 19th century. The Atwood Grove became the largest grapefruit grove in the world, with a yearly output of 80,000 boxes of fruit. There, pink grapefruit

3560-504: The Americas. In sub-Saharan Africa, the Citrus swallowtail, Papilio demodocus , is a minor pest of Citrus plantations. Grapefruits are subject to several diseases of Citrus trees, including citrus tristeza virus , citrus canker (caused by a bacterium, Xanthomonas ), and the vector -transmitted citrus greening disease , where the vector is a psyllid bug, and the pathogen is a bacterium, Liberibacter . Grapefruit originated as

3649-562: The Caribbean, Indian Ocean, Pacific Islands, East Africa, Natal, north and eastern parts of South America, and southeast Asia. The modern ethnic mix of many nations, settled in the last two centuries, has been influenced by table sugar. Beginning in the late 18th century, the production of sugar became increasingly mechanized. The steam engine first powered a sugar mill in Jamaica in 1768, and, soon after, steam replaced direct firing as

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3738-569: The Greek soldiers carried back some of the "honey-bearing reeds". Sugarcane remained a limited crop for over a millennium. Sugar was a rare commodity and traders of sugar became wealthy. Venice, at the height of its financial power, was the chief sugar-distributing center of Europe . Moors started producing it in Sicily and Spain . Only after the Crusades did it begin to rival honey as a sweetener in Europe. The Spanish began cultivating sugarcane in

3827-655: The Mediterranean by Arab traders around the 10th century CE. Sweet oranges were brought to Europe by the Genoese and Portuguese from Asia during the 15th to 16th century. Mandarins were not introduced until the 19th century. Oranges were introduced to Florida by Spanish colonists. In cooler parts of Europe, citrus fruit was grown in orangeries starting in the 17th century; many were as much status symbols as functional agricultural structures. The generic name Citrus originates from Latin , where it denoted either

3916-587: The United States (including California). In the northern hemisphere, the beet-growing season ends with the start of harvesting around September. Harvesting and processing continues until March in some cases. The availability of processing plant capacity and the weather both influence the duration of harvesting and processing – the industry can store harvested beets until processed, but a frost-damaged beet becomes effectively unprocessable. The United States sets high sugar prices to support its producers, with

4005-433: The bond between them being an acetal bond which can be broken by an acid. Given (higher) heats of combustion of 1349.6 kcal/mol for sucrose, 673.0 for glucose, and 675.6 for fructose, hydrolysis releases about 1.0 kcal (4.2 kJ) per mole of sucrose, or about 3 small calories per gram of product. The biosynthesis of sucrose proceeds via the precursors UDP-glucose and fructose 6-phosphate , catalyzed by

4094-529: The center of origin of the genus Citrus is likely the southeast foothills of the Himalayas , in a region stretching from eastern Assam , northern Myanmar , to western Yunnan . It diverged from a common ancestor with Poncirus trifoliata . A change in climate conditions during the Late Miocene (11.63 to 5.33 mya ) resulted in a sudden speciation event . The species resulting from this event include

4183-492: The citric acid content of lemon juice, and nearly 50% more than orange juice. In Costa Rica, especially in Atenas , grapefruit are often cooked with to balance their sourness, rendering them as sweets ; or they are stuffed with dulce de leche as a dessert . In Haiti, grapefruit is used primarily for its juice ( jus de Chadèque ), but also is used to make jam ( confiture de Chadèque ). Grapefruit varieties are differentiated by

4272-414: The container or package insert . In 2022, world production of grapefruits (combined with pomelos ) was 9.8 million tonnes , led by China with 53% of the world total with Vietnam as a secondary producer (table). Grapefruits are hosts for fruit flies (family Tephritidae ) such as A. suspensa , which lay their eggs in overripe or spoiled grapefruits, sometimes causing serious damage in plantations in

4361-463: The damaging citrus tristeza virus , while the aphid-like Asian citrus psyllid can carry the bacterium which causes the serious citrus greening disease . This threatens production in Florida, California, and worldwide. Citrus groves are attacked by parasitic Nematodes including citrus ( Tylenchulus semipenetrans ) and sheath nematodes ( Hemicycliophora spp.). Citrus plants can develop

4450-432: The deficiency condition chlorosis , characterized by yellowing leaves. The condition is often caused by an excessively high pH ( alkaline soil ), which prevents the plant from absorbing nutrients such as iron, magnesium , and zinc needed to produce chlorophyll . Some Citrus species contain significant amounts of furanocoumarins . In humans, some of these act as strong photosensitizers when applied topically to

4539-415: The desired fruiting cultivars onto rootstocks selected for disease resistance and hardiness. The trees are not generally frost hardy. They thrive in a consistently sunny, humid environment with fertile soil and adequate water. The colour of citrus fruits only develops in climates with a ( diurnal ) cool winter. In tropical regions with no winter at all, citrus fruits remain green until maturity, hence

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4628-523: The earliest evidence are seeds recovered from the Hala Sultan Tekke site of Cyprus , dated to around 1200 BCE. Other archaeobotanical evidence includes pollen from Carthage dating back to the 4th century BCE; and carbonized seeds from Pompeii dated to around the 3rd to 2nd century BCE. The earliest complete description of the citron was written by Theophrastus , c.  310 BCE . Lemons, pomelos, and sour oranges were introduced to

4717-404: The earliest historical mentions of sugar cane is included along with the fact that their knowledge of sugar cane was derived from India . By about 500 BCE, residents of modern-day India began making sugar syrup, cooling it in large flat bowls to produce raw sugar crystals that were easier to store and transport. In the local Indian language, these crystals were called khanda ( खण्ड ), which

4806-756: The early 21st century mainly by the increase in cultivation areas, improvements in transportation and packaging, rising incomes and consumer preference for healthy foods. In 2019–20, world production of oranges was estimated to be 47.5 million tonnes, led by Brazil, Mexico, the European Union, and China as the largest producers. Among the diseases of citrus plantations are citrus black spot (a fungus), citrus canker (a bacterium), citrus greening (a bacterium, spread by an insect pest), and sweet orange scab (a fungus, Elsinöe australis ). Citrus plants are liable to infestation by ectoparasites which act as vectors to plant diseases: for example, aphids transmit

4895-450: The effect that many former purchasers of sugar have switched to corn syrup (beverage manufacturers) or moved out of the country (candy manufacturers). The low prices of glucose syrups produced from wheat and corn ( maize ) threaten the traditional sugar market. Used in combination with artificial sweeteners , they can allow drink manufacturers to produce very low-cost goods. Since the 6th century BCE, cane sugar producers have crushed

4984-484: The effects of those drugs, leading to multiple side-effects such as abnormal heart rhythms, bleeding inside the stomach, low blood pressure, difficulty breathing, and dizziness. The evergreen grapefruit trees usually grow to around 4.5–6 m (15–20 ft) tall, although they may reach 13.7 m (45 ft). The leaves are up to 15 cm (6 in) long, thin, glossy, and dark green. They produce 5 cm (2 in) white flowers with four or five petals. The fruit

5073-406: The enzyme sucrose-6-phosphate synthase . The energy for the reaction is gained by the cleavage of uridine diphosphate (UDP). Sucrose is formed by plants, algae and cyanobacteria but not by other organisms . Sucrose is the end product of photosynthesis and is found naturally in many food plants along with the monosaccharide fructose. In many fruits, such as pineapple and apricot , sucrose

5162-512: The first fruit, which were then called shaddocks . The grapefruit then probably originated as a naturally occurring hybrid between the two plants some time after they had been introduced there. A hybrid fruit, called forbidden fruit , was first documented in 1750 (along with 14 other citrus fruits including the guiney orange) by a Welshman, the Rev. Griffith Hughes, in his The Natural History of Barbados . However, Hughes's forbidden fruit may have been

5251-508: The flesh color of fruit they produce. Common varieties are yellow and pink pulp colors. Flavors range from highly acidic and somewhat sour to sweet and tart, resulting from composition of sugars (mainly sucrose ), organic acids (mainly citric acid), and monoterpenes and sesquiterpenes providing aromas. Grapefruit mercaptan , a sulfur -containing terpene , is one of the aroma compounds influencing taste and odor of grapefruit, compared with other citrus fruits. With its sharp taste, grapefruit

5340-478: The forbidden fruit was "maliformis". Macfadyen's and Hughes's descriptions differ, so it is not clear that the two reports are describing the same plant. It has been suggested that Hughes's golden orange may actually have been a grapefruit, while his forbidden fruit was a different variety that may since have been lost. A citrus called forbidden fruit or shaddette has been discovered in Saint Lucia ; it may be

5429-761: The genus Citrus associated with modern Citrus cultivars are the mandarin orange , pomelo , and citron . Almost all of the common commercially important citrus fruits (sweet oranges, lemons, grapefruit, limes, and so on) are hybrids between these three species, their main progenies, and other wild Citrus species within the last few thousand years. Citrus plants are native to subtropical and tropical regions of Asia, Island Southeast Asia , Near Oceania , and northeastern and central Australia. Domestication of citrus species involved much hybridization and introgression , leaving much uncertainty about when and where domestication first happened. A genomic, phylogenic, and biogeographical analysis by Wu et al. (2018) has shown that

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5518-555: The genus Citrus . The false oranges, Oxanthera from New Caledonia , have been transferred to the Citrus genus on phylogenetic evidence. The earliest introductions of citrus species by human migrations was during the Austronesian expansion ( c.  3000 –1500 BCE), where Citrus hystrix , Citrus macroptera , and Citrus maxima were among the canoe plants carried by Austronesian voyagers eastwards into Micronesia and Polynesia . The citron ( Citrus medica )

5607-465: The harvested vegetable material from sugarcane in order to collect and filter the juice. They then treat the liquid, often with lime ( calcium oxide ), to remove impurities and then neutralize it. Boiling the juice then allows the sediment to settle to the bottom for dredging out, while the scum rises to the surface for skimming off. In cooling, the liquid crystallizes, usually in the process of stirring, to produce sugar crystals. Centrifuges usually remove

5696-410: The liquid, which gets recycled in the crystalliser stages. When economic constraints prevent the removal of more sugar, the manufacturer discards the remaining liquid, now known as molasses , or sells it on to producers of animal feed. Sieving the resultant white sugar produces different grades for selling. It is difficult to distinguish between fully refined sugar produced from beet and cane. One way

5785-453: The locules, which provide nourishment to the fruit as it develops. The genus is commercially important with cultivars of many species grown for their fruit. Some cultivars have been developed to be easy to peel and seedless, meaning they are parthenocarpic . The fragrance of citrus fruits is conferred by flavonoids and limonoids in the rind. The flavonoids include various flavanones and flavones . The carpels are juicy; they contain

5874-557: The main genus, Citrus , and the genus Poncirus (such as the trifoliate orange ), which is closely enough related that it can still be hybridized with all other citrus and used as rootstock. These estimates are made using genetic mapping of plant chloroplasts . A DNA study published in Nature in 2018 concludes that the genus Citrus evolved in the foothills of the Himalayas , in the area of Assam (India), western Yunnan (China), and northern Myanmar . The three ancestral species in

5963-402: The manner that glucose and other reducing sugars do. Since sucrose contains no anomeric hydroxyl groups, it is classified as a non- reducing sugar . Sucrose crystallizes in the monoclinic space group P2 1 with room-temperature lattice parameters a = 1.08631 nm, b = 0.87044 nm, c = 0.77624 nm, β = 102.938°. The purity of sucrose is measured by polarimetry , through

6052-630: The other hand, grow only in cooler temperate regions and do not tolerate extreme heat . About 80 percent of sucrose is derived from sugarcane, the rest almost all from sugar beets. In mid-2018, India and Brazil had about the same production of sugar – 34 million tonnes – followed by the European Union , Thailand , and China as the major producers. India, the European Union, and China were the leading domestic consumers of sugar in 2018. Beet sugar comes from regions with cooler climates: northwest and eastern Europe, northern Japan, plus some areas in

6141-410: The pericarp is the mesocarp, which in citrus fruits consists of the white, spongy albedo or pith. The innermost layer of the pericarp is the endocarp. This surrounds a variable number of carpels , shaped as radial segments. The seeds, if present, develop inside the carpels. The space inside each segment is a locule filled with juice vesicles , or pulp. From the endocarp, string-like "hairs" extend into

6230-554: The plant described by Hughes and Macfadyen. The name grape-fruit was used more and more during the 19th century to refer to pomelos, to the consternation of some. It was brought to Florida by the French businessman Count Odet Philippe in 1823, in what is now known as Safety Harbor . Further crosses have produced the tangelo (1905), the Minneola tangelo (1931), and the oroblanco (1984). Its true origins were not determined until

6319-403: The presence of essential oil glands. The fruit is a hesperidium , a specialised berry with multiple carpels , globose to elongated, 4–30 cm (1.6–11.8 in) long and 4–20 cm (1.6–7.9 in) diameter, with a leathery rind or "peel" called a pericarp . The outermost layer of the pericarp is an "exocarp" called the flavedo , commonly referred to as the zest . The middle layer of

6408-601: The production and release of ethylene is gradual. According to the UN Food and Agriculture Organization , world production of all citrus fruits in 2016 was 124 million tonnes, with about half of this production as oranges. At US $ 15.2 billion equivalent in 2018, citrus trade makes up nearly half of the world fruit trade, which was US$ 32.1 billion that year. According to the United Nations Conference on Trade and Development , citrus production grew during

6497-433: The production of sugar beet. As a result, some countries that traditionally produced cane sugar (such as Egypt ) have built new beet sugar factories since about 2008. Some sugar factories process both sugar cane and sugar beets and extend their processing period in that way. The production of sugar leaves residues that differ substantially depending on the raw materials used and on the place of production. While cane molasses

6586-471: The rotation of plane-polarized light by a sugar solution. The specific rotation at 20 °C (68 °F) using yellow "sodium-D" light (589 nm) is +66.47°. Commercial samples of sugar are assayed using this parameter. Sucrose does not deteriorate at ambient conditions. Sucrose does not melt at high temperatures. Instead, it decomposes at 186 °C (367 °F) to form caramel . Like other carbohydrates , it combusts to carbon dioxide and water by

6675-463: The simplified equation: C 12 H 22 O 11 + 12 O 2 → 12 CO 2 + 11 H 2 O Mixing sucrose with the oxidizer potassium nitrate produces the fuel known as rocket candy that is used to propel amateur rocket motors. C 12 H 22 O 11 + 6 KNO 3 → 9 CO + 3 N 2 + 11 H 2 O + 3 K 2 CO 3 This reaction is somewhat simplified though. Some of the carbon does get fully oxidized to carbon dioxide, and other reactions, such as

6764-449: The skin, while others interact with medications when taken orally in the grapefruit juice effect . Due to the photosensitizing effects of certain furanocoumarins, some Citrus species cause phytophotodermatitis , a potentially severe skin inflammation resulting from contact with a light-sensitizing botanical agent followed by exposure to ultraviolet light. In Citrus species, the primary photosensitizing agent appears to be bergapten ,

6853-543: The source of process heat. During the same century, Europeans began experimenting with sugar production from other crops. Andreas Marggraf identified sucrose in beet root and his student Franz Achard built a sugar beet processing factory in Silesia (Prussia). The beet-sugar industry took off during the Napoleonic Wars , when France and the continent were cut off from Caribbean sugar. In 2009, about 20 percent of

6942-449: The sucrose in plants and for some it is their main food source. Although honeybees consume sucrose, the honey they produce consists primarily of fructose and glucose, with only trace amounts of sucrose. As fruits ripen, their sucrose content usually rises sharply, but some fruits contain almost no sucrose at all. This includes grapes, cherries, blueberries, blackberries, figs, pomegranates, tomatoes, avocados, lemons and limes. Sucrose

7031-550: The tree, which often appear similar to bunches of grapes. In 1830, the Jamaican version of the plant was given the botanical name Citrus paradisi by the Scottish physician and botanist James Macfadyen . Macfadyen identified two varieties – one called forbidden fruit , the other Barbadoes Grape Fruit . Macfadyen distinguished between the two plants by fruit shape with the Barbados grapefruit being piriform ( pear shaped) while

7120-480: The tropical "green oranges". The terms 'ripe' and 'mature' are widely used synonymously, but they mean different things. A mature fruit is one that has completed its growth phase. Ripening is the sequence of changes within the fruit from maturity to the beginning of decay. These changes involve the conversion of starches to sugars, a decrease in acids, softening, and s change in the fruit's colour. Citrus fruits are non- climacteric and respiration slowly declines and

7209-451: The uncrystallized syrup. The producers can then either sell the sugar product for use as is, or process it further to produce lighter grades. The later processing may take place in another factory in another country. Sugarcane is a major component of Brazilian agriculture; the country is the world's largest producer of sugarcane and its derivative products, such as crystallized sugar and ethanol ( ethanol fuel ). Beet sugar producers slice

7298-401: The washed beets, then extract the sugar with hot water in a " diffuser ". An alkaline solution (" milk of lime " and carbon dioxide from the lime kiln) then serves to precipitate impurities (see carbonatation ). After filtration, evaporation concentrates the juice to a content of about 70% solids, and controlled crystallisation extracts the sugar. A centrifuge removes the sugar crystals from

7387-406: The weather is too cold to grow it outdoors; Citrofortunella hybrids have good cold resistance. Lemons appear in paintings, pop art, and novels. A wall painting in the tomb of Nakht in 15th century BC Egypt depicts a woman in a festival, holding a lemon. In the 17th century, Giovanna Garzoni painted a Still Life with Bowl of Citrons , the fruits still attached to leafy flowering twigs, with

7476-448: The world's sugar was produced from beets. Today, a large beet refinery producing around 1,500 tonnes of sugar a day needs a permanent workforce of about 150 for 24-hour production. Table sugar (sucrose) comes from plant sources. Two important sugar crops predominate: sugarcane ( Saccharum spp. ) and sugar beets ( Beta vulgaris ), in which sugar can account for 12% to 20% of the plant's dry weight. Minor commercial sugar crops include

7565-481: The α form. Fructose exists as a mixture of five tautomers but sucrose has only the β- D -fructofuranose form. Unlike most disaccharides , the glycosidic bond in sucrose is formed between the reducing ends of both glucose and fructose, and not between the reducing end of one and the non-reducing end of the other. This linkage inhibits further bonding to other saccharide units, and prevents sucrose from spontaneously reacting with cellular and circulatory macromolecules in

7654-541: Was also introduced early into the Mediterranean basin from India and Southeast Asia. It was introduced via two ancient trade routes: an overland route through Persia , the Levant and the Mediterranean islands; and a maritime route through the Arabian Peninsula and Ptolemaic Egypt into North Africa. Although the exact date of the original introduction is unknown due to the sparseness of archaeobotanical remains,

7743-527: Was associated with real commercial success, which came after the discovery of a red grapefruit growing on a pink variety. The Texas Legislature designated this variety the official "State Fruit of Texas" in 1993. Using radiation to trigger mutations , new varieties were developed to retain the red tones that typically faded to pink. The 'Rio Red' variety is a 1984 registered Texas grapefruit with registered trademarks Rio Star and Ruby-Sweet , also sometimes promoted as Reddest and Texas Choice . The 'Rio Red'

7832-482: Was coined in 1860 by the French chemist Marcellin Berthelot . Saccharose is an obsolete name for sugars in general, especially sucrose. In sucrose, the monomers glucose and fructose are linked via an ether bond between C1 on the glucosyl subunit and C2 on the fructosyl unit. The bond is called a glycosidic linkage . Glucose exists predominantly as a mixture of α and β "pyranose" anomers , but sucrose has only

7921-686: Was discovered in 1906. Citrus Ancestral species: Citrus maxima – Pomelo Citrus medica – Citron Citrus reticulata – Mandarin orange Citrus micrantha – a papeda Citrus hystrix – Kaffir lime Citrus cavaleriei – Ichang papeda Citrus japonica – Kumquat Important hybrids: Citrus × aurantiifolia – Key lime Citrus × aurantium – Bitter orange Citrus × latifolia – Persian lime Citrus × limon – Lemon Citrus × limonia – Rangpur Citrus × paradisi – Grapefruit Citrus × sinensis – Sweet orange Citrus × tangerina – Tangerine See also List of citrus fruits . Citrus

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