Theobroma cacao(cacao treeorcocoa tree) is a small (6–12 m (20–39 ft) tall)evergreentreein the familyMalvaceae.[1][3]Its seeds -cocoa beans- are used to makechocolate liquor,cocoa solids,cocoa butterandchocolate.[4]Although the tree is native to thetropicsof theAmericas,the largest producer of cocoa beans in 2022 wasIvory Coast.The plant'sleavesare alternate, entire, unlobed, 10–50 cm (4–20 in) long and 5–10 cm (2–4 in) broad.

Theobroma cacao
Cacao fruits on the tree
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Malvales
Family: Malvaceae
Genus: Theobroma
Species:
T. cacao
Binomial name
Theobroma cacao
Synonyms[1][2]
  • Cacao minaGaertn.
  • Cacao minusGaertn.
  • Cacao sativaAubl.
  • Cacao theobromaTussac
  • Theobroma cacao f. leiocarpum(Bernoulli) Ducke
  • Theobroma cacao subsp. leiocarpum(Bernoulli) Cuatrec.
  • Theobroma cacao var. leiocarpum(Bernoulli) Cif.
  • Theobroma cacao subsp. sativa(Aubl.) León
  • Theobroma cacao var. typicaCif.
  • Theobroma caribaeaSweet
  • Theobroma integerrimaStokes
  • Theobroma kalaguaDe Wild.
  • Theobroma leiocarpumBernoulli
  • Theobroma pentagonumBernoulli
  • Theobroma saltzmannianaBernoulli
  • Theobroma sapidumPittier
  • Theobroma sativa(Aubl.) Lign. & Le Bey
  • Theobroma sativa var. leucospermaA. Chev.
  • Theobroma sativa var. melanospermaA. Chev.
  • Theobroma sativum(Aubl.) Lign. & Bey

Description

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Flowers

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Theflowersare produced in clusters directly on thetrunkand older branches; this is known ascauliflory.The flowers are small,1–2 cm (381316in) diameter, with pinkcalyx.Thefloral formula,used to represent the structure of aflowerusing numbers, is ✶ K5 C5 A(5°+52)G(5).[5]

While many of the world's flowers are pollinated bybees(Hymenoptera) orbutterflies/moths(Lepidoptera), cacao flowers are pollinated by tiny flies,Forcipomyiabitingmidges.[6][7]Using the natural pollinatorForcipomyiamidges produced more fruit than using artificial pollinators.[7]

Cacao flowers

Fruit

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Thefruit,called a cacao pod, is ovoid, 15–30 cm (6–12 in) long and 8–10 cm (3–4 in) wide, ripening yellow to orange, and weighs about 500 g (1 lb) when ripe. The pod contains 20 to 60seeds,usually called "beans", embedded in a white pulp.

The seeds are the main ingredient ofchocolate,while the pulp is used in some countries to prepare refreshingjuice,smoothies,jelly,andcream.Usually discarded until practices changed in the 21st century, the fermented pulp may be distilled into an alcoholic beverage.[8]Each seed contains a significant amount of fat (40–50%) ascocoa butter.

The fruit's active constituent is the stimulanttheobromine,a compound similar tocaffeine.[9]

Fruit

Nomenclature

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The generic nameTheobromais derived from theGreekfor "food of the gods"; fromθεός(theos), meaning 'god' or 'divine', andβρῶμα(broma), meaning 'food'. The specific namecacaois theHispanizationof the name given to the plant in indigenousMesoamerican languagessuch askakawinTzeltal,KʼicheʼandClassic Maya;kagawinSayula Popoluca;andcacahuatlinNahuatlmeaning "bean of the cocoa-tree".[10]

Taxonomy

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Cacao (Theobroma cacao) is one of 26 species belonging to thegenusTheobromaclassified under the subfamilyByttnerioideaeof the mallowfamilyMalvaceae.[1]

In 2008, researchers proposed a new classification based uponmorphological,geographic, andgenomiccriteria: 10 groups have been named according to their geographic origin or the traditionalcultivarname. These groups are: Amelonado, Criollo, Nacional, Contamana, Curaray, Cacao guiana, Iquitos, Marañon, Nanay, and Purús.[11]

Distribution and domestication

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T. cacaois widely distributed from southeasternMexicoto theAmazon basin.There were originally two hypotheses about its domestication; one said that there were two foci for domestication, one in theLacandon Junglearea of Mexico and another in lowlandSouth America.[citation needed]More recent studies of patterns of DNA diversity, however, suggest that this is not the case. One study sampled 1241 trees and classified them into 10 distinct genetic clusters.[11]This study also identified areas, for example aroundIquitosin modernPeruandEcuador,where representatives of several genetic clusters originated more than 5000 years ago, leading to development of the variety,Nacional cocoa bean.[12]This result suggests that this is whereT. cacaowas originally domesticated, probably for the pulp that surrounds the beans, which is eaten as a snack and fermented into a mildly alcoholic beverage.[13]Using the DNA sequences and comparing them with data derived from climate models and the known conditions suitable for cacao, one study refined the view of domestication, linking the area of greatest cacao genetic diversity to a bean-shaped area that encompassesEcuador,the border between Brazil and Peru and the southern part of the Colombian–Brazilian border.[14]Climate models indicate that at the peak of thelast ice age21,000 years ago, when habitat suitable for cacao was at its most reduced, this area was still suitable, and so provided arefugiumfor species.

Cacao trees grow well asunderstoryplants in humid forest ecosystems. This is equally true of abandoned cultivated trees, making it difficult to distinguish truly wild trees from those whose parents may originally have been cultivated.[citation needed]

Cultivation

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Toasted cacao beans, ready for use

In 2016, cocoa beans were cultivated on roughly 10,200,000 hectares (25,000,000 acres) worldwide.[15]Cocoa beans are grown by large agroindustrial plantations and small producers, the bulk of production coming from millions of farmers with small plots.[16]A tree begins to bear when it is four or five years old. A mature tree may have 6,000 flowers in a year, yet only about 20 pods. About 1,200 seeds (40 pods) are required to produce 1 kg (2.2 lb) ofcocoa paste.

Historically, chocolate makers have recognized three maincultivar groupsof cacao beans used to make cocoa and chocolate: Forastero, Criollo and Trinitario.[17]The most prized, rare, and expensive is the Criollo group, the cocoa bean used by theMaya.[18]Only 10% of chocolate is made from Criollo, which is arguably less bitter and more aromatic than any other bean. In November 2000, the cacao beans coming fromChuaowere awarded an appellation of origin under the titleCacao de Chuao(fromSpanish:'cacao of Chuao').[19]

The cacao bean in 80% of chocolate is made using beans of the Forastero group, the main and most ubiquitous variety being the Amenolado variety, while the Arriba variety (such as the Nacional variety) are less commonly found in Forastero produce. Forastero trees are significantly hardier and more disease-resistant than Criollo trees, resulting in cheaper cacao beans.[20]

Major cocoa bean processors includeHershey's,NestléandMars.Chocolate can be made fromT. cacaothrough a process of steps that involve harvesting, fermenting ofT. cacaopulp, drying, harvesting, and then extraction.[21]RoastingT. cacaoby using superheated steam was found to be better than conventional oven-roasting because it resulted in the same quality of cocoa beans in a shorter time.[21]

Production

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Cocoa bean production – 2022
Country Production
(tonnes)
Ivory Coast 2,230,000
Ghana 1,108,663
Indonesia 667,296
Ecuador 337,149
Cameroon 300,000
Nigeria 280,000
World 5,874,582
Source:FAOSTATof theUnited Nations[22]

In 2022, world production of cocoa beans was 5.9 milliontonnes,led byIvory Coastwith 38% of the total. Other major producers wereGhana(19%) andIndonesia(11%).

Conservation

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The pests and diseases to which cacao is subject, along with climate change, mean that new varieties will be needed to respond to these challenges. Breeders rely on the genetic diversity conserved in fieldgenebanksto create new varieties, because cacao hasrecalcitrant seedsthat cannot be stored in a conventional genebank.[23]In an effort to improve the diversity available to breeders, and ensure the future of the field genebanks, experts have drawn up A Global Strategy for the Conservation and Use of Cacao Genetic Resources, as the Foundation for a Sustainable Cocoa Economy.[24]The strategy has been adopted by the cacao producers and their clients, and seeks to improve the characterization of cacao diversity, the sustainability and diversity of the cacao collections, the usefulness of the collections, and to ease access to better information about the conserved material. Some natural areas of cacao diversity are protected by various forms of conservation, for example national parks. However, a recent study of genetic diversity and predicted climates[14]suggests that many of those protected areas will no longer be suitable for cacao by 2050. It also identifies an area aroundIquitosinPeruthat will remain suitable for cacao and that is home to considerable genetic diversity, and recommends that this area be considered for protection. Other projects, such as theInternational Cocoa Quarantine Centre,aim to combat cacao diseases and preserve genetic diversity.

Phytopathogens (parasitic organisms) cause much damage toTheobroma cacaoplantations around the world. Many of those phytopathogens, which include many of the pests named below, were analyzed using mass spectrometry and allow for guiding on the correct approaches to get rid of the specific phytopathogens. This method was found to be quick, reproducible, and accurate showing promising results in the future to prevent damage toTheobroma cacaoby various phytopathogens.[25]

A specific bacteriumStreptomyces camerooniansiswas found to be beneficial forT. cacaoby helping plant growth by accelerating seed germination ofT. cacao,inhibiting growth of various types of microorganisms (such as different oomycetes, fungi, and bacteria), and preventing rotting byPhytophthora megakarya.[26]

Pests

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Various plant pests and diseases can cause serious problems for cacao production.[27]

Genome

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Genomic information
Map showing genetic clusters ofTheobroma cacao
NCBIgenome ID572
Ploidydiploid
Genome size345.99 Mb
Number ofchromosomes10 pairs
Year of completion2010

ThegenomeofT. cacaois diploid, its size is 430 Mbp,and it comprises 10chromosomepairs (2n=2x=20). In September 2010, a team of scientists announced a draft sequence of the cacao genome (Matina1-6 genotype).[28]In a second, unrelated project, the International Cocoa Genome Sequencing Consortium-ICGS, coordinated by CIRAD,[29]first published[30]in December 2010 (online, paper publication in January 2011), the sequence of the cacao genome, of the Criollo cacao (of a landrace from Belize, B97-61/B2). In their publication, they reported a detailed analysis of the genomic and genetic data.

The sequence of the cacao genome identified 28,798 protein-coding genes, compared to the roughly 23,000 protein-coding genes of thehuman genome.About 20% of the cacao genome consists oftransposable elements,a low proportion compared to other plant species. Many genes were identified as coding forflavonoids,aromaticterpenes,theobromineand many othermetabolitesinvolved in cocoa flavor and quality traits, among which a relatively high proportion code forpolyphenols,which constitute up to 8% of cacao pods dry weight. The cacao genome appears close to the hypotheticalhexaploidancestor of alldicotyledonousplants,[31]and it is proposed as an evolutionary mechanism by which the 21 chromosomes of the dicots' hypothetical hexaploid ancestor underwent major fusions leading to cacao's 10 chromosome pairs.

The genome sequence enables cacao molecular biology and breeding for elite varieties through marker-assisted selection, in particular for genetic resistance tofungal,oomycete and viral diseases responsible for huge yield losses each year. In 2017–18, due to concerns about survivability of cacao plants in an era ofglobal warmingin which climates become more extreme in the narrow band of latitudes where cacao is grown (20 degrees north and south of theequator), the commercial company,Mars, Incorporatedand theUniversity of California, Berkeleyare usingCRISPRto adjustDNAfor improvedhardinessof cacao in hot climates.[32]

History of cultivation

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Domestication

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The cacao tree, native of the Amazon rainforest, was first domesticated at least 5,300 years ago, in equatorial South America from theSanta Ana-La Florida(SALF) site in what is present-day southeastEcuador(Zamora-Chinchipe Province) by theMayo-Chinchipeculture before being introduced in Mesoamerica.[33]

In Mesoamerica, ceramic vessels with residues from the preparation of cacao beverages have been found from theEarly Formative(1900–900 BC) period. For example, one such vessel found at anOlmecarchaeological site on the Gulf Coast ofVeracruz,Mexico dates cacao's preparation by pre-Olmec peoples as early as 1750 BC.[34]On the Pacific coast ofChiapas,Mexico, aMokayaarchaeological site provides evidence of even earlier cacao beverages, to 1900 BC.[34]The initial domestication was probably related to the making of a fermented alcoholic beverage.[35]In 2018, researchers who analysed the genome of cultivated cacao trees concluded that the domesticated cacao trees all originated from a single domestication event that occurred about 3,600 years ago somewhere in Central America.[36]

Ancient uses

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Several mixtures of cacao are described in ancient texts, for ceremonial or medicinal, as well as culinary, purposes. Some mixtures includedmaize,chili,vanilla(Vanilla planifolia), and honey.Archaeologicalevidence for use of cacao, while relatively sparse, has come from the recovery of whole cacao beans atUaxactun,Guatemala[37]and from the preservation of wood fragments of the cacao tree atBelizesites includingCuelloandPulltrouser Swamp.[38]In addition, analysis of residues from ceramic vessels has found traces oftheobromineandcaffeinein early formative vessels from Puerto Escondido, Honduras (1100–900 BC) and in middle formative vessels fromColha, Belize(600–400 BC) using similar techniques to those used to extract chocolate residues from four classic period (around 400 AD) vessels from a tomb at the Maya archaeological site ofRio Azul.As cacao is the only known commodity from Mesoamerica containing both of thesealkaloidcompounds, it seems likely these vessels were used as containers for cacao drinks. In addition, cacao is named in ahieroglyphictext on one of the Rio Azul vessels. Cacao is also believed to have been ground by the Aztecs and mixed with tobacco for smoking purposes.[citation needed]Cocoa was being domesticated by the Mayo Chinchipe of the upper Amazon around 3,000 BC.[39]

TheMayabelieved thekakaw(cacao) was discovered by the gods in a mountain that also contained other delectable foods to be used by them. According toMaya mythology,thePlumed Serpentgave cacao to the Maya after humans were created from maize by divine grandmother goddessXmucane.[40]The Maya celebrated an annual festival in April to honor their cacao god,Ek Chuah,an event that included thesacrifice of a dogwith cacao-colored markings, additional animal sacrifices, offerings of cacao, feathers and incense, and an exchange of gifts. In a similar creation story, theMexica(Aztec) godQuetzalcoatldiscovered cacao (cacahuatl:"bitter water" ), in a mountain filled with other plant foods.[41]Cacao was offered regularly to a pantheon of Mexica deities and theMadrid Codexdepicts priests lancing their ear lobes (autosacrifice) and covering the cacao with blood as a suitable sacrifice to the gods. The cacao beverage was used as aritualonly by men, as it was believed to be an intoxicating food unsuitable for women and children.[42]

Cacao beans constituted both a ritual beverage and a majorcurrencysystem inpre-ColumbianMesoamericancivilizations. At one point, the Aztec empire received a yearly tribute of 980 loads (Classical Nahuatl:xiquipilli) of cacao, in addition to other goods. Each load represented exactly 8,000 beans.[43]The buying power of quality beans was such that 80–100 beans could buy a new cloth mantle. The use of cacao beans as currency is also known to have spawned counterfeiters during the Aztec empire.[44]

Modern history

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Immigrant workers from India rela xing on a cacao estate inTrinidad,1903[45]

The first European knowledge about chocolate came in the form of a beverage which was first introduced to the Spanish at their meeting withMoctezumain theAzteccapital ofTenochtitlanin 1519.[citation needed]Cortésand others noted the vast quantities of this beverage the Aztec emperor consumed, and how it was carefully whipped by his attendants beforehand. Examples of cacao beans, along with other agricultural products, were brought back to Spain at that time, but it seems the beverage made from cacao was introduced to the Spanish court in 1544 by Kekchi Maya nobles brought from the New World to Spain byDominicanfriarsto meetPrince Philip.[46]Within a century, chocolate had spread to France, England and elsewhere inWestern Europe.Demand for this beverage led the French to establish cacaoplantationsin theCaribbean,while Spain subsequently developed their cacao plantations in theirVenezuelanandPhilippine colonies(Bloom 1998, Coe 1996).[47]A painting by Dutch Golden Age artistAlbert Eckhoutshows a wild cacao tree in mid-seventeenth century Dutch Brazil. The Nahuatl-derived Spanish wordcacaoentered scientific nomenclature in 1753 after theSwedishnaturalistLinnaeuspublished his taxonomic binomial system and coined the genus and speciesTheobroma cacao.Traditionalpre-Hispanicbeverages made with cacao are still consumed inMesoamerica.These include theOaxacanbeverage known astejate.

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See also

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References

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  43. ^J. Bergmann (1969).
  44. ^S. Coe (1994).
  45. ^Head 1903,p. ii (frontispiece)
  46. ^(Coe and Coe 1996)
  47. ^Alexander Walker (1822).Colombia, relación geográfica, topográfica, agrícola, comercial y política de este país: adaptada para todo lector en general y para el comerciante y colono en particular.Tomo II. Londres: Banco de la República, pp. 284.

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Further reading

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