Tannic acid

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Tannic_acid 

 

Tannic acid

Names
IUPAC name 1,2,3,4,6-penta-O-{3,4-dihydroxy-5-[(3,4,5-trihydroxybenzoyl)oxy]benzoyl}-D-glucopyranose
Systematic IUPAC name 2,3-dihydroxy-5-({[(2R,3R,4S,5R,6R)-3,4,5,6-tetrakis({3,4-dihydroxy-5-[(3,4,5-trihydroxyphenyl)carbonyloxy]phenyl}carbonyloxy)oxan-2-yl]methoxy}carbonyl)phenyl 3,4,5-trihydroxybenzoate
Other names Acidum tannicum Gallotannic acid Digallic acid Gallotannin Tannimum Quercitannin Oak bark tannin Quercotannic acid Querci-tannic acid Querco-tannic acid
Identifiers
CAS Number	1401-55-4
3D model (JSmol)	Interactive image
Beilstein Reference	8186386
ChEBI	CHEBI:75211
ChEMBL	ChEMBL506247
ChemSpider	17286569
ECHA InfoCard	100.014.321
IUPHAR/BPS	4319
KEGG	C13452
PubChem CID	16129878
UNII	28F9E0DJY6
CompTox Dashboard (EPA)	DTXSID2026076
InChI[show]
SMILES[show]
Properties
Chemical formula	C76H52O46
Molar mass	1701.19 g/mol
Density	2.12g/cm3
Melting point	decomposes above 200 °C
Solubility in water	2850 g/L or 250 g/L
Solubility	100 g/L in ethanol 1 g/L in glycerol and acetone insoluble in benzene, chloroform, diethyl ether, petroleum, carbon disulfide, carbon tetrachloride.
Acidity (pKa)	ca. 6
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

A bottle of tannic acid (water solution).

Tannic acid is a specific form of tannin, a type of polyphenol. Its weak acidity (pK_a around 6) is due to the numerous phenol groups in the structure. The chemical formula for commercial tannic acid is often given as C₇₆H₅₂O₄₆, which corresponds with decagalloyl glucose, but in fact it is a mixture of polygalloyl glucoses or polygalloyl quinic acid esters with the number of galloyl moieties per molecule ranging from 2 up to 12 depending on the plant source used to extract the tannic acid. Commercial tannic acid is usually extracted from any of the following plant parts: Tara pods (Caesalpinia spinosa), gallnuts from Rhus semialata or Quercus infectoria or Sicilian sumac leaves (Rhus coriaria).

According to the definitions provided in external references such as international pharmacopoeia, Food Chemicals Codex and FAO-WHO tannic acid monograph only tannins sourced from the above-mentioned plants can be considered as tannic acid. Sometimes extracts from chestnut or oak wood are also described as tannic acid but this is an incorrect use of the term. It is a yellow to light brown amorphous powder; 2850 grams dissolves in one litre of water (1.7 moles per liter). 

While tannic acid is a specific type of tannin (plant polyphenol), the two terms are sometimes (incorrectly) used interchangeably. The long-standing misuse of the terms, and its inclusion in scholarly articles has compounded the confusion. This is particularly widespread in relation to green tea and black tea, both of which contain tannin but not tannic acid.

Tannic acid is not an appropriate standard for any type of tannin analysis because of its poorly defined composition.

Quercitannic and gallotannic acids

Quercitannic acid is one of the two forms of tannic acid found in oak bark and leaves. The other form is called gallotannic acid and is found in oak galls.

The quercitannic acid molecule is also present in quercitron, a yellow dye obtained from the bark of the Eastern black oak (Quercus velutina), a forest tree indigenous in North America. It is described as a yellowish-brown amorphous powder. 

In 1838, Jöns Jacob Berzelius wrote that quercitannate is used to dissolve morphine.

In 1865 in the fifth volume of "A dictionary of chemistry", Henry Watts wrote :

It exhibits with ferric salts the same reactions as gallotannic acid. It differs however from the latter in not being convertible into gallic acid, and not yielding pyrogallic acid by dry distillation. It is precipitated by sulfuric acid in red flocks. (Stenhouse, Ann. Ch. Pharm. xlv. 16.)
According to Rochleder (ibid lxiii. 202), the tannic acid of black tea is the same as that of oak-bark.

In 1880, Etti gave for it the molecular formula C₁₇H₁₆O₉. He described it as an unstable substance, having a tendency to give off water to form anhydrides (called phlobaphenes), one of which is called oak-red (C₃₄H₃₀O₁₇). For him, it was not a glycoside.

In Allen's "Commercial Organic Analysis", published in 1912, the formula given was C₁₉H₁₆O₁₀.

Other authors gave other molecular formulas like C₂₈H₂₆O₁₅, while another formula found is C₂₈H₂₄O₁₁.

According to Lowe, two forms of the principle exist – one soluble in water, of the formula C₂₈H₂₈O₁₄, and the other scarcely soluble, C₂₈H₂₄O₁₂. Both are changed by the loss of water into oak red, C₂₈H₂₂O₁₁.

Quercitannic acid was for a time a standard used to assess the phenolic content in spices, given as quercitannic acid equivalent.

In an interesting historical note, the inventor Edward G. Acheson (Inventor of Carborundum) discovered that gallotannic acid greatly improved the plasticity of clay. In his report of this discovery in 1904 he noted that the only known historical reference to the use of organic material added to clay is the use of straw mixed with clay described in the Bible, Exodus 1:11 and that the Egyptians must have been aware of his (re-)discovery. He stated "This explains why the straw was used and why the children of Israel were successful in substituting stubble for straw, a course that would hardly be possible, were the fibre of the straw depended upon as a bond feasible for the clay, but quite reasonable where the extract of the plant was used."

Uses

Tannins are a basic ingredient in the chemical staining of wood, and are already present in woods like oak, walnut, and mahogany. Tannic acid can be applied to woods low in tannin so chemical stains that require tannin content will react. The presence of tannins in the bark of redwood (Sequoia) is a strong natural defense against wildfire, decomposition, and infestation by certain insects such as termites. It is found in the seeds, bark, cones, and heartwood.

Tannic acid is a common mordant used in the dyeing process for cellulose fibers such as cotton, often combined with alum and/or iron. The tannin mordant should be done first as metal mordants combine well with the fiber-tannin complex. However this use has lost considerable interest.

Similarly tannic acid can also be used as an aftertreatment to improve wash fastness properties of acid dyed polyamide. It is also an alternative for fluorcarbon aftertreatments to impart anti-staining properties to polyamide yarn or carpets. However, due to economic considerations currently the only widespread use as textile auxiliary is the use as an agent to improve chlorine fastness, i.e. resistance against dye bleaching due to cleaning with hypochlorite solutions in high-end polyamide 6,6-based carpets and swimwear. It is, however, used in relatively small quantities for the activation of upholstery flock; this serves as an anti-static treatment.

Tannic acid is used in the conservation of ferrous (iron based) metal objects to passivate and inhibit corrosion. Tannic acid reacts with the corrosion products to form a more stable compound, thus preventing further corrosion from taking place. After treatment the tannic acid residue is generally left on the object so that if moisture reaches the surface the tannic acid will be rehydrated and prevent or slow any corrosion. Tannic acid treatment for conservation is very effective and widely used but it does have a significant visual effect on the object, turning the corrosion products black and any exposed metal dark blue. It should also be used with care on objects with copper alloy components as the tannic acid can have a slight etching effect on these metals.

Tannic acid is also found in commercially available iron/steel corrosion treatments, such as Hammerite Kurust.

Use in food

Use of tannic acid in food applications is widespread; significant amounts are used as process aids in beer clarification, aroma compound in soft drinks and juices. Also important are applications in the wine industry, where it finds use as a natural clarifying agent, colour stabilizer and taste enhancer.

In many parts of the world, such uses are permitted. In the United States, tannic acid is generally recognized as safe by the Food and Drug Administration.

According to EU directive 89/107/EEC tannic acid cannot be considered as a food additive and consequently does not hold an E number. Under directive 89/107/EEC tannic acid can be referred to as a food ingredient. The E-number E181 is sometimes incorrectly used to refer to tannic acid; this in fact refers to the INS number assigned to tannic acid under the FAO-WHO Codex Alimentarius system.

Uses as a medication

In conjunction with magnesium and sometimes activated charcoal, tannic acid was once used as a treatment for many toxic substances, such as strychnine, mushroom, and ptomaine poisonings in the late 19th and early 20th centuries.

The introduction of tannic acid treatment of severe burn injuries in the 1920s significantly reduced mortality rates. During World War I, tannic acid dressings were prescribed to treat "burns, whether caused by incendiary bombs, mustard gas, or lewisite. After the war this use was abandoned due to the development of more modern treatment regimens. 

Tannic acid is still used in pharmaceutical applications to produce albumin tannate which is used as an antidiarrheal agent. Tannic acid is also used to produce tannate salts of certain antihistamine and antitussive products to impart increased stability or slow release properties to the active pharmaceutical ingredient. Further to this, tannic acid is the principal but perhaps minimally effective ingredient in anti-allergy sprays.

Tannins have also been reported to exert many physiological effects, such as to accelerate blood clotting, reduce blood pressure, decrease the serum lipid level, produce liver necrosis, and modulate immunoresponses. This would explain common folklore such as that soaking feet in tannic acid (or strong tea) can treat or prevent blisters, foot odor and rough, dry feet.

Hazards

Tannic acid could cause potential health hazards such as damage to the eye, skin, respiratory tract, and gastrointestinal tract. It may cause irritation, redness, pain, blurred vision, and possible eye damage. When tannic acid is absorbed through the skin in harmful amounts, it may cause irritation, redness, and pain. Nausea, vomiting and diarrhoea are symptoms of tannic acid ingestion and prolonged exposure may cause liver damage. Upon inhalation, tannic acid may cause respiratory tract irritation.

Crocodilian coloration

Skin color in Crocodilia (crocodiles and alligators) is very dependent on water quality. Algae-laden waters produce greener skin, while tannic acid in the water from decay of leaves from overhanging trees (which produces some types of blackwater rivers) often produce darker skin in these animals.

History of chocolate

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/History_of_chocolate 

 

"Traités nouveaux & curieux du café du thé et du chocolate", by Philippe Sylvestre Dufour, 1685.

The history of chocolate began in Mesoamerica. Fermented beverages made from chocolate date back to 450 BC. The Aztecs believed that cacao seeds were the gift of Quetzalcoatl, the god of wisdom, and the seeds once had so much value that they were used as a form of currency. Originally prepared only as a drink, chocolate was served as a bitter liquid, mixed with spices or corn puree. It was believed to be an aphrodisiac and to give the drinker strength. Today, such drinks are also known as "Chilate" and are made by locals in the South of Mexico. After its arrival to Europe in the sixteenth century, sugar was added to it and it became popular throughout society, first among the ruling classes and then among the common people. In the 20th century, chocolate was considered essential in the rations of United States soldiers during war.

The word "chocolate" comes from the Classical Nahuatl word Xocolātl, and entered the English language from the Spanish language.

History

An Aztec woman generates foam by pouring chocolate from one vessel to another in the Codex Tudela

Cultivation, consumption, and cultural use of cacao were extensive in Mesoamerica where the cacao tree is native. When pollinated, the seed of the cacao tree eventually forms a kind of sheath, or ear, 20" long, hanging from the tree trunk itself. Within the sheath are 30 to 40 brownish-red almond-shaped beans embedded in a sweet viscous pulp. While the beans themselves are bitter due to the alkaloids within them, the sweet pulp may have been the first element consumed by humans.

Cacao pods grow in a wide range of colors, from pale yellow to bright green, all the way to dark purple or crimson. The skin can also vary greatly - some are sculpted with craters or warts, while others are completely smooth. This wide range in type of pods is unique to cacaos in that their color and texture does not necessarily determine the ripeness or taste of the beans inside.

Evidence suggests that it may have been fermented and served as an alcoholic beverage as early as 1400 BC.

Cultivation of the cacao was not an easy process. Part of this was because cacao trees in their natural environment grow to 60 feet tall or more. When the trees were grown in a plantation; however, they grew to around 20 feet tall.

While researchers do not agree on which Mesoamerican culture first domesticated the cacao tree, the use of the fermented bean in a drink seems to have arisen in North America (Mesoamerica—Central America and Mexico). Scientists have been able to confirm its presence in vessels around the world by evaluating the "chemical footprint" detectable in the micro samples of contents that remain. Ceramic vessel with residues from the preparation of chocolate beverages have been found at archaeological sites dating back to the Early Formative (1900–900 BC) period. For example, one such vessel found at an Olmec archaeological site on the Gulf Coast of Veracruz, Mexico dates chocolate's preparation by pre-Olmec peoples as early as 1750 BC. On the Pacific coast of Chiapas, Mexico, a Mokayanan archaeological site provides evidence of cacao beverages dating even earlier, to 1900 BC.

Pueblo people, who lived in an area that is now the U.S. Southwest, imported cacao from Mesoamerican cultures in southern Mexico between 900 and 1400. They used it in a common beverage consumed by everyone in their society.

Archaeological evidence of Cacao in Mesoamerica

Nature Ecology & Evolution reported probably the earliest cacao use from approximately 5,300 years ago recovered from the Santa Ana (La Florida) site in southeast Ecuador. Another find of chemically traced cacao was in 1984 when a team of archaeologists in Guatemala explored the Mayan site of Río Azul. They discovered fifteen vessels surrounding male skeletons in the royal tomb. One of these vessels was beautifully decorated and covered in various Mayan glyphs. One of these glyphs translated to "kakaw", also known as cacao. The inside of the vessel was lined with a dark-colored powder, which was scraped off for further testing. Once the archaeologists took this powder to the Hershey Center for Health and Nutrition to be tested, they found trace amounts of theobromine in the powder, a major indicator of cacao. This cacao was dated to sometime between 460 and 480 AD.

 

Cacao powder was also found in beautifully decorated bowls and jars, known as tecomates, in the city of Puerto Escondido. Once thought to have been a very rare commodity, cacao was found in many more tecomates than once thought possible. However, since this powder was only found in bowls of higher quality, it led archaeologists to believe that only wealthier people could afford such bowls, and therefore the cacao. The cacao tecomates are thought to have been a centerpiece to social gatherings between people of high social status.

Olmec use

Earliest evidence of domestication of the cacao plant dates to the Olmec culture from the Preclassic period. The Olmecs used it for religious rituals or as a medicinal drink, with no recipes for personal use. Little evidence remains of how the beverage was processed.

Mayan use

The Mayans, (in Guatemala), by contrast, do leave some surviving writings about cacao which confirm the identification of the drink with the gods. The Dresden Codex specifies that it is the food of the rain deity Kon, the Madrid Codex that gods shed their blood on the cacao pods as part of its production. The Maya people gathered once a year to give thanks to the god Ek Chuah who they saw as the Cacao god. The consumption of the chocolate drink is also depicted on pre-Hispanic vases. The Maya seasoned their chocolate by mixing the roasted cacao seed paste into a drink with water, chile peppers and cornmeal, transferring the mixture repeatedly between pots until the top was covered with a thick foam.

There were many uses for cacao among the Maya. It was used in official ceremonies and religious rituals, at feasts and festivals, as funerary offerings, as tribute, and for medicinal purposes. Both cacao itself and vessels and instruments used for the preparation and serving of cacao were used for important gifts and tribute. Cacao beans were used as currency, to buy anything from avocados to turkeys to sex. A rabbit, for example, was worth ten cacao beans, (called “almonds” by the early sixteenth-century chronicler Francisco Oviedo y Valdés), a slave about a hundred, and the services of a prostitute, eight to ten “according to how they agree,”. The beans were also used in betrothal and marriage ceremonies among the Maya, especially among the upper classes.

“The form of the marriage is: the bride gives the bridegroom a small stool painted in colors, and also gives him five grains of cacao, and says to him “These I give thee as a sign that I accept thee as my husband.” And he also gives her some new skirts and another five grains of cacao, saying the same thing.”

Maya preparation of cacao started with cutting open cacao pods to expose the beans and the fleshy pulp. The beans were left out to ferment for a few days. In some cases, the beans were also roasted over an open fire in order to add a smoky flavor to it. The beans then had their husks removed and were ground into a paste. Since sweeteners were rarely used by Maya, they flavored their cacao paste with additives like flowers, vanilla pods, and chilies. The vessel used to serve this chocolate liquid was stubbier by nature to help froth the liquid better, which was very important to the Maya. The vessels also tended to be decorated in intricate designs and patterns, which tended to only be accessible by the rich.

Aztec use

By 1400, the Aztec Empire took over a sizable part of Mesoamerica. They were not able to grow cacao themselves, but were forced to import it. All of the areas that were conquered by the Aztecs that grew cacao beans were ordered to pay them as a tax, or as the Aztecs called it, a "tribute". The cacao bean became a form of currency. The Spanish conquistadors left records of the value of the cacao bean, noting for instance that 100 beans could purchase a canoe filled with freshwater or a turkey hen. The Aztecs associated cacao with the god Quetzacoatl, whom they believed had been condemned by the other gods for sharing chocolate with humans. Unlike the Maya of Yucatán, the Aztecs drank chocolate cold. It was consumed for a variety of purposes, as an aphrodisiac or as a treat for men after banquets, and it was also included in the rations of Aztec soldiers.

History in Europe

Early history

Until the 16th century, the cacao tree was wholly unknown to Europeans.

Christopher Columbus encountered the cacao bean on his fourth mission to the Americas on August 15, 1502, when he and his crew seized a large native canoe that proved to contain among other goods for trade, cacao beans. His son Ferdinand commented that the natives greatly valued the beans, which he termed almonds, "for when they were brought on board ship together with their goods, I observed that when any of these almonds fell, they all stooped to pick it up, as if an eye had fallen." But while Columbus took cacao beans with him back to Spain, it made no impact until Spanish friars introduced chocolate to the Spanish court.

A Lady Pouring Chocolate by Jean-Étienne Liotard (1744)

Spanish conquistador Hernán Cortés may have been the first European to encounter chocolate when he observed it in the court of Montezuma in 1519. In 1568, Bernal Díaz, who accompanied Cortés in the conquest of Mexico, wrote of this encounter which he witnessed:

From time to time they served him [Montezuma] in cups of pure gold a certain drink made from cacao. It was said that it gave one power over women, but this I never saw. I did see them bring in more than fifty large pitchers of cacao with froth in it, and he drank some of it, the women serving with great reverence.

José de Acosta, a Spanish Jesuit missionary who lived in Peru and then Mexico in the later 16th century, described its use more generally:

Loathsome to such as are not acquainted with it, having a scum or froth that is very unpleasant taste. Yet it is a drink very much esteemed among the Indians, wherewith they feast noble men who pass through their country. The Spaniards, both men and women that are accustomed to the country are very greedy of this chocolate. They say they make diverse sorts of it, some hot, some cold, and some temperate, and put therein much of that "chili"; yea, they make paste thereof, the which they say is good for the stomach and against the catarrh.

After the Spanish conquest of the Aztecs, chocolate was imported to Europe. In the beginning, Spaniards would use it as a medicine to treat illnesses such as abdominal pain because it had a bitterness to it. Once sweetened, it transformed. It quickly became a court favorite. It was still served as a beverage, but the addition of sugar or honey counteracted the natural bitterness. The Spaniards initially intended to recreate the original taste of the Mesoamerican chocolate by adding similar spices, but this habit had faded away by the end of the eighteenth century. Within about a hundred years, chocolate established a foothold throughout Europe.

According to the authority on the Spanish language, the Royal Spanish Academy, the Spanish word "chocolate" is derived from the Nahuatl word "xocolatl" (pronounced Nahuatl pronunciation: [ ʃoˈkolaːtɬ]), which is made up from the words "xococ" meaning sour or bitter, and "atl" meaning water or drink. However, as William Bright noted the word "chocolatl" doesn't occur in central Mexican colonial sources making this an unlikely derivation. Santamaria gives a derivation from the Yucatec Maya word "chokol" meaning hot, and the Nahuatl "atl" meaning water. More recently Dakin and Wichman derive it from another Nahuatl term, "chicolatl" from Eastern Nahuatl meaning "beaten drink". They derive this term from the word for the frothing stick, "chicoli". The word xocoatl means beverage of the maize. The words "cacaua atl" mean drink of cacao. The word "xocolatl" does not appear in Molina's dictionary, Vocabulario en Lengua Castellana y Mexicana y Mexicana y Castellana.

Expansion

An early 20th-century chocolate advertisement

The new craze for chocolate brought with it a thriving slave market, as between the early 17th and late 19th centuries the laborious and slow processing of the cacao bean was manual. Cacao plantations spread, as the English, Dutch, and French colonized and planted. With the depletion of Mesoamerican workers, largely to disease, cocoa beans production was often the work of poor wage laborers and African slaves. 

1729 - The first mechanic cocoa grinder was invented in Bristol, UK. Walter Churchman petitions king of England for patent and sole use of an invention for the “expeditious, fine and clean making of chocolate by an engine.” The patent was granted by His Majesty King George II to Walter Churchman for a water engine used to make chocolate. Churchman probably used water-powered edge runners for preparing cacao beans by crushing on a far larger scale than previously. The patent for a chocolate refining process was later bought by J. S. Fry & Sons in 1761. 

Wind-powered and horse-drawn mills were used to speed production, augmenting human labor. Heating the working areas of the table-mill, an innovation that emerged in France in 1732, also assisted in extraction. The Chocolaterie Lombart, created in 1760, claimed to be the first chocolate company in France, ten years before Pelletier et Pelletier.

New processes that speed the production of chocolate emerged early in the Industrial Revolution. In 1815, Dutch chemist Coenraad van Houten introduced alkaline salts to chocolate, which reduced its bitterness. A few years thereafter, in 1828, he created a press to remove about half the natural fat (cacao butter) from chocolate liquor, which made chocolate both cheaper to produce and more consistent in quality. This innovation introduced the modern era of chocolate. Known as "Dutch cocoa", this machine-pressed chocolate was instrumental in the transformation of chocolate to its solid form when in 1847 Joseph Fry learned to make chocolate moldable by adding back melted cacao butter. Milk had sometimes been used as an addition to chocolate beverages since the mid-17th century, but in 1875 Daniel Peter invented milk chocolate by mixing a powdered milk developed by Henri Nestlé with the liquor. In 1879, the texture and taste of chocolate was further improved when Rodolphe Lindt invented the conching machine.

Lindt & Sprüngli AG, a Swiss-based concern with global reach, had its start in 1845 as the Sprüngli family confectionery shop in Zurich that added a solid-chocolate factory the same year the process for making solid chocolate was developed and later bought Lindt's factory. Besides Nestlé, several chocolate companies had their start in the late 19th and early 20th centuries. Cadbury was manufacturing boxed chocolates in England by 1868. In 1893, Milton S. Hershey purchased chocolate processing equipment at the World's Columbian Exposition in Chicago and soon began the career of Hershey's chocolates with chocolate-coated caramels.

Due to improvements in machines, chocolate underwent a transformation from a primarily a drink to food, and different types of chocolate began to emerge. At the same time, the price of chocolate began to drop dramatically in the 1890s and 1900s as the production of chocolate began to shift away from the New World to Asia and Africa. Therefore, chocolate could be purchased by the middle class. Due to the lower cost of chocolate, it happened a problem that forced child labor. In 1900–1907, Cadbury's fell into a scandal due to their reliance on West African slave plantations.

Although it was men leading the charge towards mass production of chocolate for everyday people, advertisements also targeted women, who “were charged with providing wholesome cocoa for respectable consumption within the family,”. Women were also targeted by advertising campaigns within courtship rituals, though most early advertising was aimed more at housewives and mothers than at single women.

Modern use

Roughly two-thirds of the world's cocoa is produced in Western Africa, with Ivory Coast being the largest source, producing a total crop of 1,448,992 tonnes. Ghana, Nigeria, and Cameroon are other West African countries among the top 5 cocoa-producing countries in the world. Like many food industry producers, individual cocoa farmers are at the mercy of volatile world markets. The price can vary from between £500 ($945) and £3,000 ($5,672) per ton in the space of just a few years. While investors trading in cocoa can dump shares at will, individual cocoa farmers can not ramp up production and abandon trees at anywhere near that pace.

Only three to four percent of "cocoa futures" contracts traded in the cocoa markets ever end up in the physical delivery of cocoa. Every year seven to nine times more cocoa is bought and sold on the exchange than exists.

Kola nut

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Kola_nut 

 

Kola nut – pod (with seeds inside their white testa), and seeds (whole without testa and split into cotyledons).

 

The kola nut is the fruit of the kola tree, a genus (Cola) of trees that are native to the tropical rainforests of Africa. The caffeine-containing fruit of the tree is used as a flavoring ingredient in beverages, and is the origin of the term "cola".

General description

Cola acuminata

The kola nut is a caffeine-containing nut of evergreen trees of the genus Cola, primarily of the species Cola acuminata and Cola nitida. Cola acuminata, an evergreen tree about 20 metres in height, has long, ovoid leaves pointed at both the ends with a leathery texture. The trees have yellow flowers with purple spots, and star-shaped fruit. Inside the fruit, about a dozen round or square seeds develop in a white seed-shell. The nut’s aroma is sweet and rose-like. The first taste is bitter, but it sweetens upon chewing. The nut can be boiled to extract the caffeine.

Kola nuts contain about 2–4% caffeine and theobromine, as well as tannins, alkaloids, saponins, and flavonoids.

Uses

The kola nut has a bitter flavor and contains caffeine. It is chewed in many West African countries, in both private and social settings. It is often used ceremonially, presented to chiefs or guests.

In folk medicine, kola nuts are considered useful for aiding digestion when ground and mixed with honey, and are used for coughs.

Kola nuts are perhaps best known to Western culture as a flavoring ingredient and one of the sources of caffeine in cola and other similarly flavored beverages, although kola nut extract (or kola flavoring) in major commercial cola drinks, such as Coca-Cola, is no longer used.

History

Human use of the kola nut, like the coffee berry and tea leaf, appears to have ancient origins. It is chewed in many West African cultures, in both private and social settings, as a source of mental stimulation.

Kola nuts are an important part of the traditional spiritual practice of culture and religion in West Africa, particularly Niger, Nigeria, Sierra Leone and Liberia. The 1970s hit "Goro City", by Manu Dibango, highlights the significance of kola nuts (called "goro" in the Hausa language) to the capital of Niger, Niamey. Kola nuts are used as a religious object and sacred offering during prayers, ancestor veneration, and significant life events, such as naming ceremonies, weddings, and funerals. They are also used in a traditional divination system called Obi divination. For this use, only kola nuts divided into four lobes are suitable. They are cast upon a special wooden board and the resulting patterns are read by a trained diviner.

They were used as a form of currency in such West African groups as the Malinke and Bambara of Mali and Senegal. They are still used as such today in certain situations such as in negotiation over bride prices or as a form of a respect or host gift to the elders of a village should one move to a village or enter a business arrangement with the village.

Cola recipe

In the 1880s, a pharmacist in Georgia, John Pemberton, took caffeine extracted from kola nuts and cocaine-containing extracts from coca leaves and mixed them with sugar, other flavorings, and carbonated water to invent Coca-Cola, the first cola soft drink. As of 2016, the cola recipe no longer contained actual kola nut extract.

Cultivation

Worldwide kola nut yield

 

Originally a tree of tropical rainforest, it needs a hot humid climate, but can withstand a dry season on sites with a high ground water level. It may be cultivated in drier areas where groundwater is available. C. nitida is a shade bearer, but develops a better spreading crown which yields more fruits in open places. Though it is a lowland forest tree, it has been found at altitudes over 300 m on deep, rich soils under heavy and evenly distributed rainfall.

Regular weeding is necessary, which can be performed manually or through the use of herbicides. Some irrigation can be provided to the plants, but it is important to remove the water through an effective drainage system, as excess water may prove to be detrimental for the growth of the plant. When not grown in adequate shade, the kola nut plant responds well to fertilizers. Usually, the plants need to be provided with windbreaks to protect them from strong gales.

Kola nuts can be harvested mechanically or by hand, by plucking them at the tree branch. Nigeria produces 52.4% of worldwide production followed by the Ivory Coast and Cameroon.  When kept in a cool, dry place, kola nuts can be stored for a long time.

Pests and diseases

The nuts are subject to attack by the kola weevil Balanogastris cola. The larvae of the moth Characoma strictigrapta that also attacks cacao bore into the nuts. Traders sometimes apply an extract of the bark of Rauvolfia vomitoria or the pulverised fruits of Xylopia and Capsicum to counteract the attack on nursery plants. The cacao pests Sahlbergella spp. have been found also on C. nitida as an alternative host plant. While seeds are liable to worm attack, the wood is subject to borer attack.

Chemical composition

Preliminary studies of phytochemicals in kola nut indicate the presence of various constituents:

• caffeine (2–3.5%)
• theobromine (1.0–2.5%)
• theophylline
• polyphenols
  • phlobaphens (kola red)
  • epicatechin
  • D-catechin
  • tannic acid
• sugar
  • cellulose
• water

Society and culture

Used in cultural traditions of the Igbo people, the presentation of kola nuts to guests or in a traditional gathering shows good will.

A kola nut ceremony is briefly described in Chinua Achebe's 1958 novel Things Fall Apart. The eating of kola nuts is referred to at least a further ten times in the novel showing the significance of the kola nut in pre-colonial 1890s Igbo culture in Nigeria. One of these sayings on kola nut in Things Fall Apart is: "He who brings kola brings life." It also features prominently in Chris Abani's 2004 novel GraceLand. The kola nut is also mentioned in The Color Purple by Alice Walker, although it is spelled "cola". 

The kola nut is mentioned in Bloc Party's song "Where is Home?" on the album A Weekend in the City. The lyric, setting a post-funeral scene for the murder of a black boy in London, reads, "After the funeral, breaking kola nuts, we sit and reminisce about the past." The kola nut is mentioned in the At the Drive-In song "Enfilade" on the album Relationship of Command. The kola nut is repeatedly mentioned in Chimamanda Ngozi Adichie's novel Half of a Yellow Sun, which also features the phrase: "He who brings the Kola nut brings life."

Theobroma cacao

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Theobroma_cacao 

 

Theobroma cacao
Cacao fruits on the tree
Scientific 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
Cacao minar Gaertn. Cacao minus Gaertn. Cacao sativa Aubl. Cacao theobroma Tussac 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. typica Cif. Theobroma caribaea Sweet Theobroma integerrima Stokes Theobroma kalagua De Wild. Theobroma leiocarpum Bernoulli Theobroma pentagonum Bernoulli Theobroma saltzmanniana Bernoulli Theobroma sapidum Pittier Theobroma sativa (Aubl.) Lign. & Le Bey Theobroma sativa var. leucosperma A. Chev. Theobroma sativa var. melanosperma A. Chev. Theobroma sativum (Aubl.) Lign. & Bey

Closed and open blossom and fruits on the trunk of Theobroma cacao (ÖBG Bayreuth)

Theobroma cacao, also called the cacao tree and the cocoa tree, is a small (4–8 m (13–26 ft) tall) evergreen tree in the family Malvaceae, native to the deep tropical regions of Mesoamerica. Its seeds, cocoa beans, are used to make chocolate liquor, cocoa solids, cocoa butter and chocolate. The largest producer of cocoa beans in 2018 was Ivory Coast, with 37% of the world total.

Description

Leaves are alternate, entire, unlobed, 10–40 cm (3.9–15.7 in) long and 5–20 cm (2.0–7.9 in) broad.

The flowers are produced in clusters directly on the trunk and older branches; this is known as cauliflory. The flowers are small, 1–2 cm (0.39–0.79 in) diameter, with pink calyx. The floral formula, used to represent the structure of a flower using numbers, is ✶ K5 C5 A(5°+5²) G(5). While many of the world's flowers are pollinated by bees (Hymenoptera) or butterflies/moths (Lepidoptera), cacao flowers are pollinated by tiny flies, Forcipomyia midges in the subfamily Forcipomyiinae. Using the natural pollinator Forcipomyia midges for Theobroma cacao was shown to have more fruit production than using artificial pollinators. The fruit, called a cacao pod, is ovoid, 15–30 cm (5.9–11.8 in) long and 8–10 cm (3.1–3.9 in) wide, ripening yellow to orange, and weighs about 500 g (1.1 lb) 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 refreshing juice, smoothies, jelly, and cream. Usually discarded until practices changed in the 21st century, the fermented pulp may be distilled into an alcoholic beverage. Each seed contains a significant amount of fat (40–50%) as cocoa butter. The fruit's active constituent is the stimulant theobromine, a compound similar to caffeine.

Taxonomy and nomenclature

Cacao (Theobroma cacao) belongs to the genus Theobroma classified under the subfamily Byttnerioideae of the mallow family Malvaceae. Cacao is one of 17 species of Theobroma.

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.

The generic name is derived from the Greek for "food of the gods"; from θεός (theos), meaning 'god', and βρῶμα (broma), meaning 'food'. The specific name cacao is the Hispanization of the name of the plant in indigenous Mesoamerican languages. The cacao was known as kakaw in Tzeltal, Kʼicheʼ and Classic Maya; kagaw in Sayula Popoluca; and cacahuatl in Nahuatl as "bean of the cocoa-tree".

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 the 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.

Currency system

Cacao beans constituted both a ritual beverage and a major currency system in pre-Columbian Mesoamerican civilizations. At one point, the Aztec empire received a yearly tribute of 980 loads (xiquipil in Nahuatl) of cacao, in addition to other goods. Each load represented exactly 8,000 beans. 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.

Cultivation

In 2016, cocoa beans were cultivated on roughly 10,196,725 hectares (25,196,660 acres) 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 (40 pods) are required to produce 1 kg (2.2 lb) 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 "Cacao de Chuao" (from Spanish-cacao of Chuao).

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.

Major cocoa bean processors include Hershey's, Nestlé and Mars, all of which purchase cocoa beans via various sources. 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 roasting (use of ovens) because it resulted in same quality of cocoa beans in a shorter amount of time.

Cocoa bean production – 2018
Country	(tonnes)
Ivory Coast	1,963,949
Ghana	947,632
Indonesia	593,832
Nigeria	332,927
Cameroon	307,867
Brazil	239,387
World	5,252,377
Source: FAOSTAT of the United Nations

Production

In 2018, world production of cocoa beans was 5.3 million tons, led by Ivory Coast with 37% of the total. Other major producers were Ghana (18%) and Indonesia (11%).

Conservation

Cacao flowers

 

Theobroma cacao

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 (parasitic organisms) 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 type of bacteria 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 (such as different oomycetes, fungi, and bacteria), 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 (but especially Sahlbergella singularis and Distantiella theobroma in West Africa and Helopeltis spp. in Southeast Asia)
  • Conopomorpha cramerella (cocoa pod borer – in Southeast Asia)
• Fungi
  • Moniliophthora roreri (frosty pod rot)
  • Moniliophthora perniciosa (witches' broom)
  • Ceratocystis cacaofunesta (mal de machete) or (Ceratocystis wilt)
  • Verticillium dahliae
  • Oncobasidium theobromae (vascular streak dieback)
• Oomycetes
  • Phytophthora spp. (black pod) especially Phytophthora megakarya in West Africa
• Viruses
  • Cacao swollen shoot virus
• Mistletoe
• Rats and other vertebrate pests (squirrels, woodpeckers, etc.)

Genome

Genomic information

Map showing genetic clusters of Theobroma cacao
NCBI genome ID	572
Ploidy	diploid
Genome size	345.99 Mb
Number of chromosomes	10 pairs
Year of completion	2010

The genome of T. cacao is diploid, its size is 430 Mbp, and it comprises 10 chromosome pairs (2n=2x=20). In September 2010, a team of scientists announced a draft sequence of the cacao genome (Matina1-6 genotype). In a second, unrelated project, the International Cocoa Genome Sequencing Consortium-ICGS, co-ordinated by CIRAD, first published 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 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 (20 degrees north and south of the equator), 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.

History of cultivation

Cultivation, use, and cultural elaboration of cacao were early and extensive in Mesoamerica. Ceramic vessels with residues from the preparation of cacao beverages have been found at archaeological sites dating back to the Early Formative (1900–900 BC) period. For example, one such vessel found at an Olmec archaeological site on the Gulf Coast of Veracruz, Mexico dates cacao's preparation by pre-Olmec peoples as early as 1750 BC. On the Pacific coast of Chiapas, Mexico, a Mokaya archaeological site provides evidence of cacao beverages dating even earlier, to 1900 BC. The initial domestication was probably related to the making of a fermented, thus alcoholic, beverage. 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.

Several mixtures of cacao are described in ancient texts, for ceremonial or medicinal, as well as culinary, purposes. Some mixtures included maize, chili, vanilla (Vanilla planifolia), and honey. Archaeological evidence for use of cacao, while relatively sparse, has come from the recovery of whole cacao beans at Uaxactun, Guatemala and from the preservation of wood fragments of the cacao tree at Belize sites including Cuello and Pulltrouser Swamp. In addition, analysis of residues from ceramic vessels has found traces of theobromine and caffeine in early formative vessels from Puerto Escondido, Honduras (1100–900 BC) and in middle formative vessels from Colha, 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 of Rio Azul. As cacao is the only known commodity from Mesoamerica containing both of these alkaloid compounds, it seems likely these vessels were used as containers for cacao drinks. In addition, cacao is named in a hieroglyphic text 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. Cocoa was being domesticated by the Mayo Chinchipe of the upper Amazon around 3,000 BC.

Modern history

Toasted cacao beans

The first European knowledge about chocolate came in the form of a beverage which was first introduced to the Spanish at their meeting with Moctezuma in the Aztec capital of Tenochtitlan in 1519. Cortés and 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 by Dominican friars to meet Prince Philip. Within a century, chocolate had spread to France, England and elsewhere in Western Europe. Demand for this beverage led the French to establish cacao plantations in the Caribbean, while Spain subsequently developed their cacao plantations in their Venezuelan and Philippine colonies (Bloom 1998, Coe 1996). A painting by Dutch Golden Age artist Albert Eckhout shows a wild cacao tree in mid-seventeenth century Dutch Brazil. The Nahuatl-derived Spanish word cacao entered scientific nomenclature in 1753 after the Swedish naturalist Linnaeus published his taxonomic binomial system and coined the genus and species Theobroma cacao. Traditional pre-Hispanic beverages made with cacao are still consumed in Mesoamerica. These include the Oaxacan beverage known as tejate.

Mythology

The Maya believed the kakaw (cacao) was discovered by the gods in a mountain that also contained other delectable foods to be used by them. According to Maya mythology, the Plumed Serpent gave cacao to the Maya after humans were created from maize by divine grandmother goddess Xmucane. The Maya celebrated an annual festival in April to honor their cacao god, Ek Chuah, an event that included the sacrifice of a dog with cacao-colored markings, additional animal sacrifices, offerings of cacao, feathers and incense, and an exchange of gifts. In a similar creation story, the Mexica (Aztec) god Quetzalcoatl discovered cacao (cacahuatl: "bitter water"), in a mountain filled with other plant foods. Cacao was offered regularly to a pantheon of Mexica deities and the Madrid Codex depicts 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 a ritual only by men, as it was believed to be an intoxicating food unsuitable for women and children.