Theobroma cacao, cocoa, cacao

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Taxonomy

cellular organisms - Eukaryota - Viridiplantae - Streptophyta - Streptophytina - Embryophyta - Tracheophyta - Euphyllophyta - Spermatophyta - Magnoliophyta - eudicotyledons - core eudicotyledons - rosids - malvids - Malvales - Malvaceae - Byttnerioideae - Theobroma - Theobroma cacao

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General information

Theobroma cacao L. is a small (4–8 m tall), shade loving, evergreen tree.

• Origins

  Origins of cocoa trees are traced to the Amazon Basin in eastern Peru and Ecuador and far western Brazil. Cocoa beans were originally cultivated by the native Aztecs of Mexico and the Mayans of the Yucatan Peninsula. By 1502, the year of first European encounter with cocoa beans (4^th Columbus voyage), the cocoa trees have been already domesticated for as long as two thousand years. A crude mixture of roasted, shelled, and then ground cocoa beans mixed with various spices and blended with hot water with occasional addition of corn meal was consumed by the wealthiest Indian families. This food-referred to as chocolatl - was perhaps recognized as having a special physiological effect (including that of an aphrodisiac) by the native populations. In its native unsweetened form, however, the chocolate proved very distasteful for the Spaniards.

• Old uses

  Chemical analyses of residues extracted from pottery vessels from Puerto Escondido in what is now Honduras show that cacao beverages were being made there before 1000 B.C., extending the confirmed use of cacao back at least 500 years. The famous chocolate beverage served on special occasions in later times in Mesoamerica, especially by elites, was made from cacao seeds. The earliest cacao beverages consumed at Puerto Escondido were likely produced by fermenting the sweet pulp surrounding the seeds. Cocoa came to Europe in the 16th century and in 1737, Linnaeus named the cocoa tree Theobroma (Food of God).

• Main cultivar groups of cacao beans

  • Criollo, the cocoa tree used by the Mayas, is highly prized and rare, less bitter and more aromatic than other beans, from which only 5–10% of chocolate is made. Criollo's cotyledons (colored flesh inside the bean) are almost white (cream-white and ivory white), rarely with very pale pinkish or mauve (lilac) shades, also in stripes or spots from white (ivory) or almost cream to pale olive, rarely with indistinct shades of very light pink.
  • Forastero, which include several sub-varieties, are significantly hardier than Criollo trees and produce cheaper cocoa beans, in fact they are used for 80% of world chocolate production. The Arriba variety is considered the best one. Forastero's cotyledons are lilac or mauve to very light violet on the two-thirds peripheral portion, and lighter to whitish in the central core.
  • Trinitario, a hybrid of Criollo and Forastero, is used in about 10–15% of chocolate production.

• Shade management systems

  • Rustic cacao management is widespread in the humid portion of West Africa and local in Latin America. It is characterized by the planting of cacao under thinned primary or older secondary forest.
  • Planted shade cacao management systems range from diverse agroforests with multiple species of planted shade trees and occasional remnant forest species to commercial shade systems where other tree crops are interspersed with planted shade trees and the cacao trees, and, finally, can be monocultural where the shade is provided by one or a few tree species.
  • Zero-shade cacao cultivation is common in Malaysia and becomes more popular in parts of Colombia and Peru.

• Processing of cocoa beans

  Despite of its popularity, cocoa is a relatively small commodity. Roughly 2.5 million kg are harvested annually compared with the hundreds of millions of kilograms produced yearly of other major crops, such as rice, wheat, corn, and soybeans. Immediately after harvest and extraction, the beans are moist and covered with pulp. The cocoa farmer must treat the cocoa to produce dry stable beans having good flavor potential. The procedure involves two major processes:
  1. Curing or fermentation For the purpose of describing the curing process, the bean may be envisaged as consisting of two main parts: mucilage (seed coat or testa and the attached pulp that surrounds it) and the nib (embryo, which bulk consists of cotyledons). Fermentation serves two major goals: remove the mucilage and inhibit germination. The methods of fermenting cocoa varies considerably from country to country and can be roughly classified as fermentation on drying platforms (picture below, Dominican Republic, Forastero requires 5-8 days of fermentation/drying for development of flavor), fermentation in heaps, fermentation in baskets, and fermentation in boxes.
  2. Drying Drying is usually done naturally by the sun on various types of platforms. This may require 5-7 days of good sunshine and high temperatures. Drying is sometimes accomplished or assisted by mechanical systems if the weather is too wet on cool. The moisture content of the beans is reduced to less than 8%, typically 7-7.5%, producing a stable product that can be stored and transported for worldwide trade: a commodity.

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Cocoa flower

Cocoa plantation

Cocoa ripe pods

Cocoa pod and cocoa bean (purple inside)

Curing and drying of cocoa beans

Stable cocoa beans are ready for transportation

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Developmental stages (life cycle)

Life Cycle Stages

• Mature seed Each seed contains a significant amount of fat (40–50% as cocoa butter) and polyphenols, which make up about 10% of the whole bean's dry weight and make mature cocoa beans bitter. Polyphenols in cocoa beans are stored in the pigment cells of the cotyledons. Depending on the amount of anthocyanins those pigment cells, also called polyphenol-storage cells, range in color from white to deep purple. Chocolate is considered the third highest contributor of antioxidants (represented by polyphenols) to American diet with 100–107 mg/day (fruits 255 mg/day, vegetables 233 mg/day). Cocoa beans contain approximately 380 known chemicals and 10 psychoactive compounds.
• Seedling Up to 2-3 months plant. Seeds germinate and convert within 5 weeks.
  • Germinated seed Hypocotyl is elongated and radicle is extended.
  • Converted seedling The shoot apex is developed and formed shoot with leaves.
• Plantlet Sturdy plantlets are used for transplanting to plantation site. Cocoa trees are usually planted under larger trees that provide shade and protection from winds. The trees must be planted in regions possessing sufficient, consistent rainfall with warm days and nights, with the range of growth generally accepted as being 20 degrees north and south of the equator.
• Immature tree Young tree incapable of flowering and fruiting.
• Mature tree Tree starts to flower and bear fruits at about 5 years of age and reaches maximum pod production in 17-18 years maintaining this level for as long as 20 years with good farming practices. When mature, the tree reaches a height and breadth similar to a fully grown apple or almond tree. Many trees produce only 50-60 usable pods per year. Fruit set (cherelles are about 14 days old and of maximum length of about 20 mm) signifies the start of the fruiting cycle. Fruiting cycle is approximately defined as the number of days (between the observation of the first fruit set and the ripening phase) required for a given crop to produce half of its total harvest a year. Length of fruiting cycle ranges from about 140 to 175 days depending on the clone of the crop.
  • Flowering Pod formation begins with the pollination of a small flower with a diameter typically about the size of a dime. Flowers occur on the main stem and primary branches of the tree. The vector of pollination is a small (2-5 mm long) insects known as midges (Diptera: Ceratopogonidae and Cecidomyiidae). Cocoa trees are continuously producing flowers and mature fruits at the same time. However, some periodicity, especially in trees planted under deep shade (rustic cultivation) is observed: there usually is greater flower production in the beginning and first half of rainy season.
  • Embryogenesis /
    Fruit development
    • Unicellular embryo /
      Cherelle Embryo remain unicellular for as long as 10 weeks after pollination.
    • Elongation /
      Young pod Length of the embryo increases until 14 weeks after pollination. The green fruit is growing.
      • Globular embryo 10-11 weeks after pollination.
      • Heart embryo
      • Cotyledonary
        embryo 11-14 weeks after pollination. True growth of the embryo; water content is steadily decreased from 98% to 80%. Fruit grows. At the end of the period maximum size of the fruit is reached.
    • Maturation /
      ripening The period starts at about 21 weeks after pollination. Darkening and increasing weight of the embryo. At full maturity, cocoa embryo water content is close to 30% (recalcitrant seed, vulnerable to desiccation as opposed to orthodox seeds, which water content can be as low as 7%). Fruit changes colors from green or dark red-purple to yellow, orange, or red, depending on the variety. The mature bean is thick walled and contains 30-40 beans, each enveloped in a sweet, white, mucilaginous pulp and loosely attached to an axial placenta. Only beans are used in chocolate manufacturing. Typical Trinitario clones take as long as 7 months to ripen whereas other types, such as Upper Amazon Forastero trees, take only 4 months to ripen.

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References

• Rusconi M, Conti A. Theobroma cacao L., the Food of the Gods: A scientific approach beyond myths and claims. Pharmacological Research 61 (2010) 5–13.
• Ciferri R and Ciferri F. The Evolution of Cultivated Cacao. Evolution, Vol. 11, No. 4 (Dec., 1957), pp. 381-397.
• Morgan J. Chocolate: a flavor and texture unlike any other. Ama J Cli,, Nutr l994:60(suppl):1065S-7S.
• Young AM. Habitat Differences in Cocoa Tree Flowering, Fruit-Set, and Pollinator Availability in Costa Rica. Journal of Tropical Ecology, Vol. 2, No. 2 (May, 1986), pp. 163-186.
• Bergmann JF. The Distribution of Cacao Cultivation in Pre-Columbian America. Annals of the Association of American Geographers, Vol. 59, No. 1 (Mar., 1969), pp. 85.
• Gorman J. The Original Cocoa Treat. Science News, Vol. 162, No. 3 (Jul. 20, 2002), p. 38.
• Ceylon Cacao. (Theobroma Cacao, L.) Bulletin of Miscellaneous Information (Royal Gardens, Kew), Vol. 1890, No. 44 (1890), pp. 170-173.
• Hunter JR. The Status of Cacao (Theobroma cacao, Sterculiaceae) in the Western Hemisphere. Economic Botany, Vol. 44, No. 4 (Oct. - Dec., 1990), pp. 425-439.
• Steinberg MK. The Globalization of a Ceremonial Tree: The Case of Cacao (Theobroma cacao) among the Mopan Maya. Economic Botany, Vol. 56, No. 1 (Jan. - Mar., 2002), pp. 58-65.
• McGovern PE. Chemical and Archaeological Evidence for the Earliest Cacao Beverages. Proceedings of the National Academy of Sciences of the United States of America, Vol. 104, No. 48 (Nov. 27, 2007), pp. 18937-18940.
• Emamdie D and Warren J. Varietal Taste Preference for Cacao Theobroma cacao L. by the Neotropical Red Squirrel Sciurus granatensis (Humboldt). Biotropica, Vol. 25, No. 3 (Sep., 1993), pp. 365-368.
• Hunter JR. The Status of Cacao (Theobroma cacao, Sterculiaceae) in the Western Hemisphere. Economic Botany, Vol. 44, No. 4 (Oct. - Dec., 1990), pp. 425-439.
• Alemanno L, Berthouly M, Michaux-Ferriere N. A Comparison between Theobroma cacao L. Zygotic Embryogenesis and Somatic Embryogenesis from Floral Explants. In Vitro Cellular & Developmental Biology. Plant, Vol. 33, No. 3 (Jul. - Sep., 1997), pp. 163-172.
• Efombag MIB et al. Effect of Fruiting Traits on the Field Resistance of Cocoa (Theobroma cacao L.) Clones to Phytophthora megakarya. J. Phytopathology 152, 557–562 (2004).
• Free full text articles in PubMed: major topic "Cacao"

Websites

• Cocoa And Chocolate, 1886
• Cocoa And Coffee, Food Microbiology, 2001 (.pdf)

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