Theobroma cacao
Theobroma cacao is a small evergreen tree in the Malvaceae family. Its seedscocoa beansare used to make chocolate liquor, cocoa solids, cocoa butter and chocolate. Although the tree is native to the tropics of the Americas, the largest producer of cocoa beans in 2022 was Ivory Coast. The plants leaves are alternate, entire, unlobed, long and broad.
Description
Flowers
The flowers are produced in clusters directly on the trunk and older branches; this is known as cauliflory. The flowers are small, diameter, with pink calyx. The floral formula, used to represent the structure of a flower using numbers, is ✶ K5 C5 A.While many of the world's flowers are pollinated by bees or butterflies/moths, cacao flowers are pollinated by tiny flies, Forcipomyia biting midges. Using the natural pollinator Forcipomyia midges produced more fruit than using artificial pollinators.
Fruit
The fruit, called a cacao pod, is ovoid, long and wide, ripening yellow to orange, and weighs about when ripe. The pod contains 20 to 60 seeds, usually called "beans", embedded in a white pulp.The seeds are the main ingredient of chocolate, while the pulp is used in some countries to prepare juice, smoothies, jelly, and cream. Usually discarded until practices changed in the 21st century, the fermented pulp may be distilled into an alcoholic beverage. The pulp tastes like lychee or tropical melon. Each seed contains a significant amount of fat as cocoa butter.
The fruit's active constituent is the stimulant theobromine, a compound similar to caffeine.
Nomenclature
The generic name Theobroma is derived from the Greek for "food of the gods"; from , meaning 'god' or 'divine', and , meaning 'food'. The specific name cacao is the Hispanization of the name given to the plant in indigenous Mesoamerican languages such as kakaw in Tzeltal, Kʼicheʼ and Classic Maya; kagaw in Sayula Popoluca; and cacahuatl in Nahuatl meaning "bean of the cocoa-tree". While the tree and seeds are generally called cacao, they are sometimes referred to as 'cocoa'.Taxonomy
Cacao is one of 26 species belonging to the genus Theobroma classified under the subfamily Byttnerioideae of the mallow family Malvaceae.In 2008, researchers proposed a new classification based upon morphological, geographic, and genomic criteria: 10 groups have been named according to their geographic origin or the traditional cultivar name. These groups are: Amelonado, Criollo, Nacional, Contamana, Curaray, Cacao guiana, Iquitos, Marañon, Nanay, and Purús.
Distribution and domestication
T. cacao is widely distributed from southeastern Mexico to the Amazon basin. There were originally two hypotheses about its domestication; one said that there were two foci for domestication, one in the Lacandon Jungle area of Mexico and another in lowland South America. 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. This study also identified areas, for example around Iquitos in modern Peru and Ecuador, where representatives of several genetic clusters originated more than 5000 years ago, leading to development of the variety, Nacional cocoa bean. This result suggests that this is where T. cacao was originally domesticated, probably for the pulp that surrounds the beans, which is eaten as a snack and fermented into a mildly alcoholic beverage. 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 encompasses Ecuador, the border between Brazil and Peru and the southern part of the Colombian–Brazilian border. Climate models indicate that at the peak of the last ice age 21,000 years ago, when habitat suitable for cacao was at its most reduced, this area was still suitable, and so provided a refugium for species.Cacao trees grow well as understory plants 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.
Cultivation
In 2023, cocoa beans were cultivated on roughly worldwide. Cocoa beans are grown by large agroindustrial plantations and small producers, the bulk of production coming from millions of farmers with small plots. 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 are required to produce of cocoa paste.Historically, chocolate makers have recognized three main cultivar groups of cacao beans used to make cocoa and chocolate: Forastero, Criollo and Trinitario. The most prized, rare, and expensive is the Criollo group, the cocoa bean used by the Maya. 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 from Chuao were awarded an appellation of origin under the title .
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 are less commonly found in Forastero produce. Forastero trees are significantly hardier and more disease-resistant than Criollo trees, resulting in cheaper cacao beans.
Major cocoa bean processors include Hershey's, Nestlé and Mars. Chocolate can be made from T. cacao through a process of steps that involve harvesting, fermenting of T. cacao pulp, drying, harvesting, and then extraction. Roasting T. cacao by 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.
Production
| Country | Production |
| 2,377,442 | |
| 653,700 | |
| 641,741 | |
| 375,719 | |
| 296,145 | |
| 295,819 | |
| 284,232 | |
| World | 5,600,100 |
In 2023, world production of cocoa beans was 5.6 million tonnes, led by Ivory Coast with 42.5% of the total. Other major producers were Ghana and Indonesia.
Conservation
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 field genebanks to create new varieties, because cacao has recalcitrant seeds that cannot be stored in a conventional genebank. 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. 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 suggests that many of those protected areas will no longer be suitable for cacao by 2050. It also identifies an area around Iquitos in Peru that 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 the International Cocoa Quarantine Centre, aim to combat cacao diseases and preserve genetic diversity.Phytopathogens cause much damage to Theobroma cacao plantations 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 to Theobroma cacao by various phytopathogens.
A specific bacterium Streptomyces camerooniansis was found to be beneficial for T. cacao by helping plant growth by accelerating seed germination of T. cacao, inhibiting growth of various types of microorganisms, and preventing rotting by Phytophthora megakarya.
Pests
Various plant pests and diseases can cause serious problems for cacao production.- Insects
- *Cocoa mirids or capsids worldwide
- *Bathycoelia thalassina - West Africa
- *Conopomorpha cramerella
- *Carmenta theobromae - C. & S. America
- Fungi
- *Moniliophthora roreri
- *Moniliophthora perniciosa
- *Ceratocystis cacaofunesta or
- *Verticillium dahliae
- *Oncobasidium theobromae
- Oomycetes
- *Phytophthora spp. especially Phytophthora megakarya in West Africa
- Viruses
- *Cacao swollen shoot virus
- Mistletoe
- Rats and other vertebrate pests
Genome
The sequence of the cacao genome identified 28,798 protein-coding genes, compared to the roughly 23,000 protein-coding genes of the human genome. About 20% of the cacao genome consists of transposable elements, a low proportion compared to other plant species. Many genes were identified as coding for flavonoids, aromatic terpenes, theobromine and many other metabolites involved in cocoa flavor and quality traits, among which a relatively high proportion code for polyphenols, which constitute up to 8% of cacao pods dry weight. The cacao genome appears close to the hypothetical hexaploid ancestor of all dicotyledonous plants, 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 to fungal, 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 of global warming in which climates become more extreme in the narrow band of latitudes where cacao is grown, the commercial company, Mars, Incorporated and the University of California, Berkeley are using CRISPR to adjust DNA for improved hardiness of cacao in hot climates.