Coffee is a brewed drink prepared from roasted seeds, called coffee beans, of the coffee plant. Coffee beans are found in coffee cherries, which grow on trees in over 70 countries, cultivated primarily in Latin America, Southeast Asia, and Africa. 'Green Unroasted' coffee is one of the most traded agricultural commodities in the world. Coffee can have a stimulating effect on humans due to its caffeine content. It is one of the most-consumed beverages in the world.
Coffee has played a crucial role in many societies. The energizing effect of the coffee bean plant is thought to have been discovered in the northeast region of Ethiopia, and the cultivation of coffee first expanded in the Arab world. The earliest credible evidence of coffee drinking appears in the middle of the 15th century, in the Sufi monasteries of Yemen in southern Arabia. From the Muslim world, coffee spread to Italy, then to the rest of Europe, to Indonesia, and to the Americas. In East Africa and Yemen, it was used in religious ceremonies. As a result, the Ethiopian Church banned its secular consumption, a ban in effect until the reign of Emperor Menelik II of Ethiopia. It was banned in Ottoman Turkey during the 17th century for political reasons, and was associated with rebellious political activities in Europe.
Coffee berries, which contain the coffee seed, or "bean", are produced by several species of small evergreen bush of the genus Coffea. The two most commonly grown are the highly regarded Coffea arabica, and the 'robusta' form of the hardier Coffea canephora. The latter is resistant to the devastating coffee leaf rust (Hemileia vastatrix). Once ripe, coffee berries are picked, processed, and dried. The seeds are then roasted to varying degrees, depending on the desired flavor. They are then ground and brewed to create coffee. Coffee can be prepared and presented in a variety of ways.
An important export commodity, coffee was the top agricultural export for twelve countries in 2004, and it was the world's seventh-largest legal agricultural export by value in 2005. Some controversy is associated with coffee cultivation and its impact on the environment. Many studies have examined the relationship between coffee consumption and certain health conditions; whether the overall effects of coffee are ultimately positive or negative has been widely disputed. The method of brewing coffee has been found to be important to its health effects.
The first reference to "coffee" in the English language, in the form chaoua, dates to 1598. In English and other European languages, coffee derives from the Ottoman Turkish kahve, via the Italian caffè. The Turkish word in turn was borrowed from the Arabic: قهوة, qahwah. Arab lexicographers maintain that qahwah originally referred to a type of wine, and gave its etymology, in turn, to the verb qahiya, signifying "to have no appetite", since this beverage was thought to dull one's hunger. Several alternative etymologies exist that hold that the Arab form may disguise a loanword from an Ethiopian or African source, suggesting Kaffa, the highland in southwestern Ethiopia as one, since the plant is indigenous to that area. However, the term used in that region for the berry and plant is bunn, the native name in Shoa being būn.'
Several species of shrub of the genus Coffea produce the berries from which coffee is extracted. The two main species commercially cultivated are Coffea canephora (predominantly a form known as 'robusta') and C. arabica. C. arabica, the original and most highly regarded species, is native to the southwestern highlands of Ethiopia and the Boma Plateau in southeastern Sudan and possibly Mount Marsabit in northern Kenya. C. canephora is native to western and central subsaharan Africa, from Guinea to the Uganda and southern Sudan. Less popular species are C. liberica, excelsa, stenophylla, mauritiana, and racemosa.
All coffee plants are classified in the large family Rubiaceae. They are evergreen shrubs or small trees that may grow 5 m (15 ft) tall when unpruned. The leaves are dark green and glossy, usually 10–15 cm (4–6 in) long and 6 cm (2.4 in) wide. The flowers are axillary, and clusters of fragrant white flowers bloom simultaneously and are followed by oval berries of about 1.5 cm (0.6 in). Green when immature, they ripen to yellow, then crimson, before turning black on drying. Each berry usually contains two seeds, but 5–10% of the berries have only one; these are called peaberries. Berries ripen in seven to nine months.
Coffea arabica is predominantly self-pollinating, and as a result the seedlings are generally uniform and vary little from their parents. In contrast, Coffea canephora, C. excelsa, and C. liberica are self-incompatible and require outcrossing. This means that useful forms and hybrids must be propagated vegetatively. Cuttings, grafting, and budding are the usual methods of vegetative propagation. On the other hand, there is great scope for experimentation in search of potential new strains.
Cultivation
The traditional method of planting coffee is to put 20 seeds in each hole at the beginning of the rainy season; half are eliminated naturally. A more effective method of growing coffee, used in Brazil, is to raise seedlings in nurseries that are then planted outside at six to twelve months. Coffee is often intercropped with food crops, such as corn, beans, or rice during the first few years of cultivation.
Of the two main species grown, arabica coffee (from C. arabica) is generally more highly regarded than robusta coffee (from C. canephora); robusta tends to be bitter and have less flavor but better body than arabica. For these reasons, about three-quarters of coffee cultivated worldwide is C. arabica. Robusta strains also contain about 40–50% more caffeine than arabica. For this reason, it is used as an inexpensive substitute for arabica in many commercial coffee blends. Good quality robusta beans are used in some espresso blends to provide a full-bodied taste, a better foam head (known as crema), and to lower the ingredient cost.
However, Coffea canephora is less susceptible to disease than C. arabica and can be cultivated in lower altitudes and warmer climates where C. arabica will not thrive. The robusta strain was first collected in 1890 from the Lomani, a tributary of the Congo River, and was conveyed from Zaire to Brussels to Java around 1900. From Java, further breeding resulted in the establishment of robusta plantations in many countries. In particular, the spread of the devastating coffee leaf rust (Hemileia vastatrix), to which C. arabica is vulnerable, hastened the uptake of the resistant robusta. Coffee leaf rust is found in virtually all countries that produce coffee.
Over 900 species of insect have been recorded as pests of coffee crops worldwide. Of these, over a third are beetles, and over a quarter are bugs. Some 20 species of nematodes, 9 species of mites, several snails and slugs also attack the crop. Birds and rodents sometimes eat coffee berries but their impact is minor compared to invertebrates. In general, arabica is the more sensitive species to invertebrate predation overall. Each part of the coffee plant is assailed by different animals. Nematodes attack the roots, and borer beetles burrow into stems and woody material, the foliage is attacked by over 100 species of larvae (caterpillars) of butterflies and moths.
Mass spraying of insecticides has often proven disastrous, as the predators of the pests are more sensitive than the pests themselves. Instead, integrated pest management has developed, using techniques such as targeted treatment of pest outbreaks, and managing crop environment away from conditions favouring pests. Branches infested with scale are often cut and left on the ground, which promotes scale parasites to not only attack the scale on the fallen branches but in the plant as well.
Production
In 2009 Brazil was the world leader in production of green coffee, followed by Vietnam, Indonesia and Colombia. Arabica coffee beans are cultivated in Latin America, eastern Africa, Arabia, or Asia. Robusta coffee beans are grown in western and central Africa, throughout southeast Asia, and to some extent in Brazil.
Beans from different countries or regions can usually be distinguished by differences in flavor, aroma, body, and acidity. These taste characteristics are dependent not only on the coffee's growing region, but also on genetic subspecies (varietals) and processing. Varietals are generally known by the region in which they are grown, such as Colombian, Java and Kona.
Preparing green coffee
Coffee berries and their seeds undergo several processes before they become the familiar roasted coffee. Berries have been traditionally selectively picked by hand; a labor intensive method, it involves the selection of only the berries at the peak of ripeness. More commonly, crops are strip picked, where all berries are harvested simultaneously regardless of ripeness by person or machine. After picking, green coffee is processed by one of two methods—the dry process method, simpler and less labor intensive as the berries can be strip picked, and the wet process method, which incorporates fermentation into the process and yields a mild coffee.
Then they are sorted by ripeness and color and the flesh of the berry is removed, usually by machine, and the seeds—usually called beans—are fermented to remove the slimy layer of mucilage still present on the bean. When the fermentation is finished, the beans are washed with large quantities of fresh water to remove the fermentation residue, which generates massive amounts of coffee wastewater. Finally, the seeds are dried. The best (but least used) method of drying coffee is using drying tables. In this method, the pulped and fermented coffee is spread thinly on raised beds, which allows the air to pass on all sides of the coffee, and then the coffee is mixed by hand. In this method the drying that takes place is more uniform, and fermentation is less likely. Most African coffee is dried in this manner and certain coffee farms around the world are starting to use this traditional method. Next, the coffee is sorted, and labeled as green coffee. Another way to let the coffee beans dry is to let them sit on a concrete patio and rake over them in the sunlight. Some companies use cylinders to pump in heated air to dry the coffee beans, though this is generally in places where the humidity is very high.
The roasting process
The next step in the process is the roasting of the green coffee. Coffee is usually sold in a roasted state, and with rare exceptions all coffee is roasted before it is consumed. It can be sold roasted by the supplier, or it can be home roasted. The roasting process influences the taste of the beverage by changing the coffee bean both physically and chemically. The bean decreases in weight as moisture is lost and increases in volume, causing it to become less dense. The density of the bean also influences the strength of the coffee and requirements for packaging.
The actual roasting begins when the temperature inside the bean reaches approximately 200 °C (392 °F), though different varieties of beans differ in moisture and density and therefore roast at different rates. During roasting, caramelization occurs as intense heat breaks down starches in the bean, changing them to simple sugars that begin to brown, changing the color of the bean. Sucrose is rapidly lost during the roasting process and may disappear entirely in darker roasts. During roasting, aromatic oils and acids weaken, changing the flavor; at 205 °C (401 °F), other oils start to develop. One of these oils is caffeol, created at about 200 °C (392 °F), which is largely responsible for coffee's aroma and flavor.
Coffee preparation
Coffee preparation is the process of turning coffee beans into a beverage. While the particular steps needed vary with the type of coffee desired and with the raw material being utilized, the process is composed of four basic steps; raw coffee beans must be roasted, the roasted coffee beans must then be ground, the ground coffee must then be mixed with hot water for a certain time (brewed), and finally the liquid coffee must be separated from the now used and unwanted grounds.
Coffee is usually brewed by the user immediately before drinking. In most areas, coffee may be purchased unprocessed, or already roasted, or already roasted and ground. Coffee is often vacuum packed to prevent oxidation and lengthen its shelf life.
Health effects of coffee
The health effects of coffee have been studied to determine how coffee drinking affects humans. Coffee contains several compounds which are known to affect human body chemistry. The coffee bean itself contains chemicals which are mild psychotropics for humans as a defense mechanism of the Coffea plant. These chemicals are toxic in large doses, or even in their normal amount when consumed by many creatures which may otherwise have threatened the beans in the wild. Coffee contains caffeine, which acts as a stimulant.
Recent research has uncovered additional stimulating effects of coffee which are not related to its caffeine content. Coffee contains an as yet unknown chemical agent which stimulates the production of cortisone and adrenaline, two stimulating hormones.
For occasions when one wants to enjoy the flavor of coffee with almost no stimulation, decaffeinated coffee (also called decaf) is available. This is coffee from which most of the caffeine has been removed, by the Swiss water process (which involves the soaking of raw beans to remove the caffeine) or the use of a chemical solvent such as trichloroethylene ("tri"), or the more popular methylene chloride, in a similar process. Another solvent used is ethyl acetate; the resultant decaffeinated coffee is marketed as "natural decaf" because ethyl acetate is naturally present in fruit. Extraction with supercritical carbon dioxide has also been employed.
Decaffeinated coffee usually loses some flavor compared to normal coffee. There are also coffee alternatives that resemble coffee in taste but contain no caffeine (see below). These are available both in ground form for brewing and in instant form.
Caffeine dependency and withdrawal symptoms are well-documented.
Scientific studies have examined the relationship between coffee consumption and an array of medical conditions. Findings have been contradictory as to whether coffee has any specific health benefits, and results are similarly conflicting regarding the potentially harmful effects of coffee consumption. Variations in findings, however, can be at least partially resolved by considering the method of preparation. Coffee prepared using paper filters removes oily components called diterpenes that are present in unfiltered coffee. Two types of diterpenes are present in coffee: kahweol and cafestol, both of which have been associated with increased risk of coronary heart disease via elevation of low-density lipoprotein (LDL) levels in blood. Metal filters, on the other hand, do not remove the oily components of coffee.
In addition to differences in methods of preparation, conflicting data regarding serving size could partially explain differences between beneficial/harmful effects of coffee consumption.
Coffee consumption has been shown to have minimal or no impact, positive or negative, on cancer development; however, researchers involved in an ongoing 22-year study by the Harvard School of Public Health state that "the overall balance of risks and benefits [of coffee consumption] are on the side of benefits." Other studies suggest coffee consumption reduces the risk of being affected by Alzheimer's disease, Parkinson's disease, heart disease, diabetes mellitus type 2, cirrhosis of the liver, and gout. A longitudinal study in 2009 showed that those who consumed a moderate amount of coffee or tea (3–5 cups per day) at midlife were less likely to develop dementia and Alzheimer's disease in late-life compared with those who drank little coffee or avoided it altogether. It increases the risk of acid reflux and associated diseases. Most of coffee's beneficial effects against type 2 diabetes are not due to its caffeine content, as the positive effects of consumption are greater in those who drink decaffeinated coffee. The presence of antioxidants in coffee has been shown to prevent free radicals from causing cell damage. A recent study showed that roast coffee, high in lipophilic antioxidants and chlorogenic acid lactones, protected primary neuronal cell cultures against hydrogen peroxide-induced cell death.
In a healthy liver, caffeine is mostly broken down by the hepatic microsomal enzymatic system. The resulting metabolites are mostly paraxanthines—theobromine and theophylline—and a small amount of unchanged caffeine is excreted by urine. Therefore, the metabolism of caffeine depends on the state of this enzymatic system of the liver. Elderly individuals with a depleted enzymatic system do not tolerate coffee with caffeine. They are recommended to take decaffeinated coffee, and this only if their stomach is healthy, because both decaffeinated coffee and coffee with caffeine cause heartburn. Moderate amounts of coffee (50–100 mg of caffeine or 5–10 g of coffee powder a day) are well tolerated by most elderly people. Excessive amounts of coffee, however, can, in many individuals, cause very unpleasant, exceptionally even life-threatening adverse effects. The benefits of coffee on abnormal liver biochemistry, cirrhosis and hepatocellular carcinoma have been reported, but there is a lack of satisfactory explanation. A possible opposite, if not antagonistic, role of coffee and Mediterranean Diet with regard to overweightness and insulin resistance is envisaged in the natural history of NAFLD (Non-Alcoholic-Fatty-Liver-Disease) . Coffee consumption can lead to iron deficiency anemia in mothers and infants. Coffee also interferes with the absorption of supplemental iron. Interference with iron absorption is due to the polyphenols present in coffee. Four major classes were identified: flavan-3-ols (monomers and procyanidins), hydroxycinnamic acids, flavonols and anthocyanidins.[103] Although the inhibition of iron absorption can cause an iron deficiency, iron is considered a carcinogen in relation to the liver. Polyphenols contained in coffee are therefore associated with decreasing the risk of liver cancer development.
American scientist Yaser Dorri has suggested that the smell of coffee can restore appetite and refresh olfactory receptors. He suggests that people can regain their appetite after cooking by smelling coffee beans, and that this method can also be used for research animals.
Over 1,000 chemicals have been reported in roasted coffee; more than half of those tested (19/28) are rodent carcinogens. Coffee's negative health effects are often blamed on its caffeine content. Instant coffee has a much greater amount of acrylamide than brewed coffee. Research suggests that drinking caffeinated coffee can cause a temporary increase in the stiffening of arterial walls. Caffeinated coffee is not recommended for everybody. It may aggravate preexisting conditions such as gastroesophageal reflux disease, migraines, arrhythmias, and cause sleep disturbances.
Coffee is no longer thought to be a risk factor for coronary heart disease. One study suggests that it may have a mixed effect on short-term memory, by improving it when the information to be recalled is related to the current train of thought but making it more difficult to recall unrelated information. Caffeine has been associated with its ability to act as an antidepressant. A review by de Paulis and Martin indicated a link between a decrease in suicide rates and coffee consumption, and suggested that the action of caffeine in blocking the inhibitory effects of adenosine on dopamine nerves in the brain reduced feelings of depression. A 1992 study concluded that about 10% of people with a moderate daily intake (235 mg per day) experienced increased depression and anxiety when caffeine was withdrawn, but a 2002 review of the literature criticised its methodology and concluded that "[t]he effects of caffeine withdrawal are still controversial." About 15% of the U.S. general population report having stopped drinking coffee altogether, citing concern about health and unpleasant side effects of caffeine.
History of coffee
The history of coffee goes at least as far back as the thirteenth century, though coffee's origin remains unclear.
It has been believed that Ethiopian ancestors of today's Oromo people were the first to discover and recognize the energizing effect of the coffee bean plant. However, no direct evidence has been found indicating where in Africa coffee grew or who among the natives might have used it, or even known about it, earlier than the 17th century. The story of Kaldi, the 9th-century Ethiopian goatherd who discovered coffee, did not appear in writing until 1671 AD and is probably apocryphal. From Ethiopia, coffee was said to have spread to Egypt and Yemen. The earliest credible evidence of either coffee drinking or knowledge of the coffee tree appears in the middle of the fifteenth century, in the Sufi monasteries of Yemen. It was in Arabia that coffee beans were first roasted and brewed, similar to modern preparation. By the 16th century, it had reached the rest of the Middle East, Persia, Turkey, and northern Africa. Coffee then spread to Italy, and to the rest of Europe, to Indonesia, and to the Americas.
Ethiopian ancestors of today's Oromo people were believed to have been the first to recognize the energizing effect of the coffee bean plant. However, no direct evidence has been found indicating where in Africa coffee grew or who among the natives might have used it as a stimulant or even known about it, earlier than the 17th century. The story of Kaldi, the 9th-century Ethiopian goatherd who discovered coffee, did not appear in writing until 1671 and is probably apocryphal. From Ethiopia, the beverage was introduced into the Arab world through Egypt and Yemen.
The earliest credible evidence of either coffee drinking or knowledge of the coffee tree appears in the middle of the fifteenth century, in the Sufi monasteries around Mokha in Yemen. It was here in Arabia that coffee beans were first roasted and brewed, in a similar way to how it is now prepared. By the 16th century, it had reached the rest of the Middle East, Persia, Turkey, and northern Africa.Coffee beans were first exported from Ethiopia to Yemen. Yemeni traders brought coffee back to their homeland and began to cultivate the bean. The first coffeehouse opened in Istanbul in 1554 The first coffee smuggled out of the Middle East was by Sufi Baba Budan from Yemen to India in 1670. Before then, all exported coffee was boiled or otherwise sterilised. Portraits of Baba Budan depict him as having smuggled seven coffee beans by strapping them to his chest. The first plants grown from these smuggled seeds were planted in Mysore. Coffee then spread to Italy, and to the rest of Europe, to Indonesia, and to the Americas.
In 1583, Leonhard Rauwolf, a German physician, gave this description of coffee after returning from a ten-year trip to the Near East:
A beverage as black as ink, useful against numerous illnesses, particularly those of the stomach. Its consumers take it in the morning, quite frankly, in a porcelain cup that is passed around and from which each one drinks a cupful. It is composed of water and the fruit from a bush called bunnu.
From the Muslim world, coffee spread to Italy. The thriving trade between Venice and North Africa, Egypt, and the Middle East brought many goods, including coffee, to the Venetian port. From Venice, it was introduced to the rest of Europe. Coffee became more widely accepted after it was deemed a Christian beverage by Pope Clement VIII in 1600, despite appeals to ban the "Muslim drink." The first European coffee house opened in Italy in 1645. The Dutch were the first to import coffee on a large scale, and they were among the first to defy the Arab prohibition on the exportation of plants or unroasted seeds when Pieter van den Broecke smuggled seedlings from Mocha, Yemen, into Europe in 1616. The Dutch later grew the crop in Java and Ceylon. The first exports of Indonesian coffee from Java to the Netherlands occurred in 1711. Through the efforts of the British East India Company , coffee became popular in England as well. Oxford's Queen's Lane Coffee House, established in 1654, is still in existence today. Coffee was introduced in France in 1657, and in Austria and Poland after the 1683 Battle of Vienna, when coffee was captured from supplies of the defeated Turks.
When coffee reached North America during the Colonial period, it was initially not as successful as it had been in Europe as alcoholic beverages remained more popular. During the Revolutionary War, however, the demand for coffee increased so much that dealers had to hoard their scarce supplies and raise prices dramatically; this was also due to the reduced availability of tea from British merchants. After the War of 1812, during which Britain temporarily cut off access to tea imports, the Americans' taste for coffee grew, and high demand during the American Civil War together with advances in brewing technology secured the position of coffee as an everyday commodity in the United States. Paradoxically, coffee consumption declined in England, giving way to tea during the 18th century. The latter beverage was simpler to make, and had become cheaper with the British conquest of India and the tea industry there. During the Age of Sail, seamen aboard ships of the British Royal Navy made substitute coffee by dissolving burnt bread in hot water.
The Frenchman Gabriel de Clieu brought a coffee plant to the French territory of Martinique in the Caribbean, from which much of the world's cultivated arabica coffee is descended. Coffee thrived in the climate and was conveyed across the Americas. The territory of San Domingo (now Haiti) saw coffee cultivated from 1734, and by 1788 it supplied half the world's coffee. However, the dreadful conditions that the slaves worked in on coffee plantations were a factor in the soon to follow Haitian Revolution. The coffee industry never fully recovered there. Meanwhile, coffee had been introduced to Brazil in 1727, although its cultivation did not gather momentum until independence in 1822. After this time, massive tracts of rainforest were cleared first from the vicinity of Rio and later São Paulo for coffee plantations. Cultivation was taken up by many countries in Central America in the latter half of the 19th century, and almost all involved the large-scale displacement and exploitation of the indigenous people. Harsh conditions led to many uprisings, coups and bloody suppression of peasants. The notable exception was Costa Rica, where lack of ready labor prevented the formation of large farms. Smaller farms and more egalitarian conditions ameliorated unrest over the 19th and 20th centuries.
Coffee has become a vital cash crop for many Third World countries. Over one hundred million people in developing countries have become dependent on coffee as their primary source of income. It has become the primary export and backbone for African countries like Uganda, Burundi, Rwanda, and Ethiopia, as well as many Central American countries.