Monday, May 30, 2011


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 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.
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.
Coffee Processing
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.
Grading the Roasted beans
Depending on the color of the roasted beans as perceived by the human eye, they will be labeled as light, medium light, medium, medium dark, dark, or very dark. A more accurate method of discerning the degree of roast involves measuring the reflected light from roasted beans illuminated with a light source in the near infrared spectrum. This elaborate light meter uses a process known as spectroscopy to return a number that consistently indicates the roasted coffee's relative degree of roast or flavor development.
Roast characteristics
Darker roasts are generally bolder because they have less fiber content and a more sugary flavor. Lighter roasts have a more complex and therefore perceived stronger flavor from aromatic oils and acids otherwise destroyed by longer roasting times. A small amount of chaff is produced during roasting from the skin left on the bean after processing. Chaff is usually removed from the beans by air movement, though a small amount is added to dark roast coffees to soak up oils on the beans.
Decaffeination may also be part of the processing that coffee seeds undergo. Seeds are decaffeinated when they are still green. Many methods can remove caffeine from coffee, but all involve either soaking the green beans in hot water (often called the "Swiss water" process) or steaming them, then using a solvent to dissolve caffeine-containing oils. Decaffeination is often done by processing companies, and the extracted caffeine is usually sold to the pharmaceutical industry.
Coffee beans must be ground and brewed to create a beverage. Almost all methods of preparing coffee require the beans to be ground and mixed with hot water for long enough to extract the flavor, but without boiling for more than an instant; boiling develops an unpleasant "cooked" flavor caused by over extraction from the beans that draws out unnecessary bitter compounds. Finally, the spent grounds are removed from the liquid, and the liquid is consumed. There are many variations in the fineness of grind, the ways in which the water extracts the flavor, additional flavorings (sugar, milk, spices), and the removal of the spent grounds. The ideal holding temperature is 79 to 85 °C (174 to 185 °F) and the ideal serving temperature is 68 to 79 °C (154 to 174 °F).
Coffee may be brewed by several methods: boiled, steeped, or pressured
The espresso method forces hot pressurized and vaporized water through ground coffee. As a result of brewing under high pressure (ideally between 9–10 atm), the espresso beverage is more concentrated (as much as 10 to 15 times the quantity of coffee to water as gravity-brewing methods can produce) and has a more complex physical and chemical constitution. A well-prepared espresso has a reddish-brown foam called crema that floats on the surface. Other pressurized water methods include the moka pot and vacuum coffee maker.
Coffee may also be brewed in cold water, resulting in a brew lower in acidity than most hot-brewing methods produce, by steeping the coarsely ground beans in cold water for several hours, then filtering them.
Once brewed, coffee may be presented in a variety of ways. Drip-brewed, percolated, or French-pressed/cafetière coffee may be served with a dairy product such as milk or cream, or dairy substitute (colloquially known as white coffee), or not (black coffee). It may be sweetened with sugar or artificial sweetener. When served cold, it is called iced coffee.
Espresso-based coffee has a wide variety of possible presentations. In its most basic form, espresso is served alone as a shot or with hot water added, known as Caffè Americano. Reversely, long black is made by pouring espresso in water, which retains the crema compared to Caffè Americano. Milk is added in various forms to espresso: steamed milk makes a caffè latte, equal parts steamed milk and milk froth make a cappuccino, and a dollop of hot foamed milk on top creates a caffè macchiato. The use of steamed milk to form patterns such as hearts or maple leaves is referred to as latte art.
A number of products are sold for the convenience of consumers who do not want to prepare their own coffee.
Instant coffee is dried into soluble powder or freeze-dried into granules that can be quickly dissolved in hot water. Originally invented in 1907, it rapidly gained in popularity in many countries in the post-war period, with Nescafé the most popular product. Many consumers determined that the convenience in preparing a cup of instant coffee more than made up for a perceived inferior taste. Paralleling (and complementing) the rapid rise of instant coffee was the coffee vending machine, invented in 1947 and multiplying rapidly through the 1950s.
Canned coffee has been popular in Asian countries for many years, particularly in China, Japan, and South Korea. Vending machines typically sell varieties of flavored canned coffee, much like brewed or percolated coffee, available both hot and cold. Japanese convenience stores and groceries also have a wide availability of bottled coffee drinks, which are typically lightly sweetened and pre-blended with milk. Bottled coffee drinks are also consumed in the United States. Liquid coffee concentrates are sometimes used in large institutional situations where coffee needs to be produced for thousands of people at the same time. It is described as having a flavor about as good as low-grade robusta coffee, and costs about 10¢ a cup to produce. The machines used can process up to 500 cups an hour, or 1,000 if the water is preheated.
Coffee can also be incorporated with alcohol in beverages—it is combined with whiskey in Irish coffee, and forms the base of alcoholic coffee liqueurs such as Kahlúa, and Tia Maria.



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