ثورة ثقافية

Coffee (Wikipedia)

Coffee is a brewed beverage prepared from roasted seeds, commonly called coffee beans, of the coffee plant. They are seeds of "coffee cherries" that grow on trees in over 50 countries. Green Coffee is the second most traded commodity in the world behind crude oil. Due to its caffeine content, coffee can have a stimulating effect in humans. Today, coffee is one of the most popular beverages worldwide.

It is supposed that the Ethiopians, the ancestors of today's Galla tribe, were the first to have discovered and recognized the energizing effect of the coffee bean plant. However, no direct evidence has ever been found revealing exactly where in Africa coffee grew, or who among the natives might have used it as a stimulant or even known about it there earlier than the seventeenth century. 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 the Yemen in southern Arabia. From Yemen, coffee spread to Egypt and Ethiopia, and by the 15th century, had reached Armenia, Persia, Turkey, and northern Africa. From the Muslim world, coffee spread to Italy, then to the rest of Europe, to Indonesia, and to the Americas.

Coffee berries, which contain the coffee bean, are produced by several species of small evergreen bush of the genus Coffea. The two most commonly grown species are Coffea canephora (also known as Coffea robusta) and Coffea arabica; less popular species are Liberica, Excelsa, Stenophylla, Mauritiana, Racemosa. These are cultivated primarily in Latin America, Southeast Asia, and Africa. Once ripe, coffee berries are picked, processed, and dried. The seeds are then roasted, undergoing several physical and chemical changes. They are 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.

Coffee has played an important role in many societies throughout history. In Africa and Yemen, it was used in religious ceremonies. As a result, the Ethiopian Church banned its secular consumption until the reign of Emperor Menelik II of Ethiopia. It was banned in Ottoman Turkey in the 17th century for political reasons, and was associated with rebellious political activities in Europe.

Coffee is an important export commodity. In 2004, coffee was the top agricultural export for 12 countries, and in 2005, it was the world's seventh-largest legal agricultural export by value.

Some controversy is associated with coffee cultivation and its impact on the environment. Many studies have examined the relationship between coffee consumption and certain medical conditions; whether the overall effects of coffee are positive or negative is still disputed.

Etymology:

The term coffee was introduced to Europe by the Ottoman Turkish kahve, which is, in turn, derived from the Arabic: قهوة‎, qahweh. The origin of the Arabic term is derived either from the name of the Kaffa region in western Ethiopia, where coffee was cultivated, or by a truncation of qahwat al-būnn, meaning "wine of the bean" in Arabic. The English word coffee first came to be used in the early to mid-1600s, but early forms of the word date to the last decade of the 1500s. In Ethiopia's neighbor Eritrea, "būnn" (also meaning "wine of the bean" in Tigrinya) is used. The Amharic and Afan Oromo name for coffee is bunna.

History:

Over the door of a Leipzig coffeeshop is a sculptural representation of a man in Turkish dress, receiving a cup of coffee from a boy.

It is supposed that the Ethiopians, the ancestors of today's Galla tribe, were the first to have discovered and recognized the energizing effect of the coffee bean plant. However, no direct evidence has ever been found revealing exactly where in Africa coffee grew or who among the natives might have used it as a stimulant or even known about it there earlier than the seventeenth century. The story of Kaldi, the 9th-century Ethiopian goatherd who discovered coffee, did not appear in writing until 1671 and is probably apocryphal. 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 the Yemen in southern Arabia. From Ethiopia, coffee spread to Egypt and Yemen. It was in Arabia that coffee beans were first roasted and brewed, similar to how it is done today. By the 15th century, it had reached the rest of the Middle East, Persia, Turkey, and northern Africa. From the Muslim world, coffee spread to Italy, then 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 Broeck smuggled seedlings from Aden 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. It 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. 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.

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 (Ponte 1). Coffee has become the primary export and backbone for African countries like Uganda, Burundi, Rwanda, and Ethiopia as well as many Central American countries.(1)

Biology:

Illustration of Coffea arabica plant and seeds

The Coffea plant is native to subtropical Africa and southern Asia. It belongs to a genus of ten species of flowering plants of the family Rubiaceae. It is an evergreen shrub or small tree that may grow 5 meters tall when unpruned. The leaves are dark green and glossy, usually 100–150 millimeters long and 60 millimeters wide. It produces clusters of fragrant white flowers that bloom simultaneously. The fruit berry is oval, about 15 millimeters long, and green when immature, but ripens to yellow, then crimson, becoming 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.

Cultivation:

Coffee is usually propagated by seeds. 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. Coffee is often intercropped with food crops, such as corn, beans, or rice, during the first few years of cultivation.

Map showing areas of coffee cultivation:
r:Coffea canephora
m:Coffea canephora and Coffea arabica
a:Coffea arabica

The two main cultivated species of the coffee plant are Coffea canephora and Coffea arabica. Arabica coffee (from C. arabica) is considered more suitable for drinking 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. However, C. canephora is less susceptible to disease than C. arabica and can be cultivated in environments where C. arabica will not thrive. Robusta coffee also contains 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 robustas are used in some espresso blends to provide a better foam head, a full-bodied result, and to lower the ingredient cost. Other cultivated species include Coffea liberica and Coffea esliaca, believed to be indigenous to Liberia and southern Sudan, respectively.

Most arabica coffee beans originate from either 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 usually have distinctive characteristics such as 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 or Kona.

Production:

Brazil is the world leader in production of green coffee, followed by Vietnam and Colombia the last of which produces a much softer coffee.

Top twenty green coffee producers — Metric Tonnes (2007) and Bags thousands (2007)
Country	Tonnes (1)	Bags thousands (2)	Footnote
Brazil	2,249,010	36,070
Vietnam	961,200	16,467
Colombia	697,377	12,515
Indonesia	676,475	7,751
Ethiopia	325,800	4,906	*
India	288,000	4,148
Mexico	268,565	4,150
Guatemala	252,000	4,100	*
Peru	225,992	2,953
Honduras	217,951	3,842
Côte d'Ivoire	170,849	2,150
Uganda	168,000	3,250
Costa Rica	124,055	1,791
Philippines	97,877	431
El Salvador	95,456	1,626
Nicaragua	90,909	1,700
Papua New Guinea	75,400	968	*
Venezuela	70,311	897
Madagascar	62,000	604	F
Thailand	55,660	653
World	7,742,675	117,319	A
No symbol = official figure, P = official figure, F = FAO estimate, * = Unofficial/semiofficial/mirror data, C = calculated figure, A = aggregate (may include official, semiofficial, or estimates) Source (1): Food and Agricultural Organization of United Nations: Economic and Social Department: The Statistical Devision Source (2):International Coffee Organization

Ecological effects:

A flowering Coffea arabica tree in a Brazilian plantation

Originally, coffee farming was done in the shade of trees, which provided a habitat for many animals and insects. This method is commonly referred to as the traditional shaded method or "shade-grown". Many farmers have decided to switch their production method to sun cultivation, a method in which coffee is grown in rows under full sun with little or no forest canopy. This causes berries to ripen more rapidly and bushes to produce higher yields, but requires the clearing of trees and increased use of fertilizer and pesticides. When compared to the sun cultivation method, traditional coffee production causes berries to ripen more slowly and produce lower yields, but the quality of the coffee is allegedly superior. In addition, the traditional shaded method is environmentally friendly and provides living space for many wildlife species. Opponents of sun cultivation say environmental problems such as deforestation, pesticide pollution, habitat destruction, and soil and water degradation are the side effects of these practices. The American Birding Association, Smithsonian Migratory Bird Center, Rainforest Alliance, and the Arbor Day Foundation have led a campaign for "shade-grown" and organic coffees, which it says are sustainably harvested. However, while certain types of shaded coffee cultivation systems show greater biodiversity than full-sun systems, they still compare poorly to native forest in terms of habitat value.

Another issue concerning coffee is its use of water. According to New Scientist, it takes about 140 litres of water to grow the coffee beans needed to produce one cup of coffee, and the coffee is often grown in countries where there is a water shortage, such as Ethiopia.

Economics:

Coffee ingestion on average is about a third of that of tap water in North America and Europe. Worldwide, 6.7 million metric tons of coffee were produced annually in 1998–2000, and the forecast is a rise to 7 million metric tons annually by 2010.

Brazil remains the largest coffee exporting nation, but in recent years, Vietnam has become a major producer of robusta beans. Indonesia is the third-largest exporter and the largest producer of washed arabica coffee. Robusta coffees, traded in London at much lower prices than New York's arabica, are preferred by large industrial clients, such as multinational roasters and instant coffee producers because of the lower cost.

The concept of fair trade labeling, which guarantees coffee growers a negotiated preharvest price, began with the Max Havelaar Foundation's labeling program in the Netherlands. In 2004, 24,222 metric tons (of 7,050,000 produced worldwide) were fair trade; in 2005, 33,991 metric tons out of 6,685,000 were fair trade, an increase from 0.34% to 0.51%. A number of studies have shown that fair trade coffee has a positive impact on the communities that grow it. A study in 2002 found that fair trade strengthened producer organizations, improved returns to small producers, and positively affected their quality of life. A 2003 study concluded that fair trade has "greatly improved the well-being of small-scale coffee farmers and their families" by providing access to credit and external development funding and greater access to training, giving them the ability to improve the quality of their coffee. The families of fair trade producers were also more stable than those who were not involved in fair trade, and their children had better access to education. A 2005 study of Bolivian coffee producers concluded that fair trade certification has had a positive impact on local coffee prices, economically benefiting all coffee producers, fair trade-certified or not.

The production and consumption of fair trade coffee has grown in recent years as some local and national coffee chains have started to offer fair trade alternatives.

Coffee as a commodity:

While coffee is not technically a commodity (it is fresh produce; its value is directly affected by the length of time it is held), coffee is bought and sold by roasters, investors and price speculators as a tradable commodity. Coffee futures contracts for Grade 3 washed arabicas are traded on the New York Mercantile Exchange (NYMEX) under ticker symbol KT, with contract deliveries occurring every year in March, May, July, September, and December. Higher and lower grade arabica coffees are sold through other channels. Futures contracts for robusta coffee are traded on the London Liffe exchange and, since 2007, on the New York ICE exchange. As of 2006 green coffee is the second most traded commodity in the world.

Processing:

Roasting:

Roasted coffee beans

Coffee berries and their seeds undergo several processes before they become the familiar roasted coffee. First, coffee berries are picked, generally by hand. 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 highly polluted coffee wastewater. Finally, the seeds are dried. The best (but least utilized) 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; 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 cement 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 next step in the process is the roasting of the green coffee. Coffee is usually sold in a roasted state, and 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 200°C, 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, acids, and caffeine weaken, changing the flavor; at 205°C, other oils start to develop. One of these oils is caffeol, created at about 200°C, which is largely responsible for coffee's aroma and flavor.

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. Such devices are routinely used for quality assurance by coffee-roasting businesses.

Darker roasts are generally smoother, because they have less fiber content and a more sugary flavor. Lighter roasts have more caffeine, resulting in a slight bitterness, and a 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 beans in hot water 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.

Storage:

Once roasted, coffee beans must be stored properly to preserve the fresh taste of the bean. Ideally, the container must be airtight and kept cool. In order of importance, air, moisture, heat, and light are the environmental factors responsible for deteriorating flavor in coffee beans.

Folded-over bags, a common way consumers often purchase coffee, are generally not ideal for long-term storage because they allow air to enter. A better package contains a one-way valve, which prevents air from entering.

Preparation:

Espresso brewing, with dark reddish-brown crema

Coffee beans must be ground and brewed in order to create a beverage. 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. Finally the spent grounds are removed from the liquid, and the liquid is drunk. 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 criteria for choosing a method include flavor and economy. Extracting as much flavor as possible from the beans (for economy) tends to impair flavor^.

The roasted coffee beans may be ground at a roastery, in a grocery store, or in the home. Most coffee is roasted and ground at a roastery and sold in packaged form, though roasted coffee beans can be ground at home, and it is possible, though complex, to roast raw beans.

Coffee beans may be ground in several ways. A burr mill uses revolving elements to shear the bean; an electric grinder smashes the beans with blunt blades moving at high speed; and a mortar and pestle crushes the beans.

The type of grind is often named after the brewing method for which it is generally used. Turkish grind is the finest grind, while coffee percolator or French press are the coarsest grinds. The most common grinds are between the extremes; a medium grind is used in most common home coffee-brewing machines.

Coffee may be brewed by several methods: boiled, steeped, or pressured.

Brewing coffee by boiling was the earliest method, and Turkish coffee is an example of this method. It is prepared by grinding or pounding the beans to a fine powder, then adding it to water and bringing it to the boil for no more than an instant in a pot called a cezve or, in Greek, a bríki. This produces a strong coffee with a layer of foam on the surface and sediment (which is not meant for drinking) settling on the bottom of the cup.

Coffee percolators and automatic coffeemakers brew coffee by gravity. In an automatic coffeemaker hot water drips onto coffee grounds held in a coffee filter made of paper, plastic, or perforated metal, allowing the water to seep through the ground coffee while extracting its oils and essences. The liquid drips through the coffee and the filter into a carafe or pot, and the spent grounds are retained in the filter. In a percolator, boiling water is forced into a chamber above a filter by steam pressure created by boiling. The water then seeps through the grounds, and the process is repeated until terminated by removing from the heat, by an internal timer, or by a thermostat that turns off the heater when the entire pot reaches a certain temperature. This thermostat also serves to keep the coffee warm (it turns on when the pot cools), but requires the removal of the basket holding the grounds after the initial brewing to avoid additional brewing as the pot reheats. Repeated boiling spoils the flavor of coffee.

Coffee may be brewed by steeping in a device such as a French press (also known as a cafetière or coffee press). Ground coffee and hot water are combined in a cylindrical vessel and left to brew for a few minutes. A circular filter which fits tightly in the cylinder fixed to a plunger is then pushed down from the top to force the grounds to the bottom. Because the coffee grounds are in direct contact with the water, all the coffee oils remain in the beverage, making it stronger and leaving more sediment than in coffee made by an automatic coffee machine. The coffee is poured from the container; the filter retains the grounds at the bottom.

The espresso method forces hot (but not boiling) pressurized 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 amount 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. The drink "Americano" is popularly thought to have been named after American soldiers in WW II who found the European way of drinking espresso too strong; baristas would cut the espresso with hot water for them.

Presentation can be an integral part of coffeehouse service, as illustrated by the fancy design layered into this latte.

Coffee may also be brewed in cold water by steeping coarsely-ground beans in cold water for several hours, then filtering^.

Presentation:

French petit noir

Once brewed, coffee may be presented in a variety of ways. Drip-brewed, percolated, or French-pressed/cafetière coffee may be served with no additives or sugar (colloquially known as black) or with milk, cream, or both. When served cold, it is called iced coffee.

Espresso-based coffee has a wide variety of possible presentations. In its most basic form, it is served alone as a shot or in the more watered-down style café américano—a shot or two of espresso with hot water added (reversing the process by adding espresso to hot water preserves the crema, and is known as a long black). Milk can be added in various forms to espresso: steamed milk makes a cafè 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. 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 preblended 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.

Types of popular coffee beverages:

Social aspects:

A coffeehouse in Palestine (1900)

Coffee was initially used for spiritual reasons. At least 1,000 years ago, traders brought coffee across the Red Sea into Arabia (modern-day Yemen), where Muslim monks began cultivating the shrub in their gardens. At first, the Arabians made wine from the pulp of the fermented coffee berries. This beverage was known as qishr (kisher in modern usage) and was used during religious ceremonies.

Coffee became the substitute beverage in spiritual practices where wine was forbidden. Coffee drinking was briefly prohibited by Muslims as haraam in the early years of the 16th century, but this was quickly overturned. Use in religious rites among the Sufi branch of Islam led to coffee's being put on trial in Mecca: it was accused of being a heretical substance, and its production and consumption were briefly repressed. It was later prohibited in Ottoman Turkey under an edict by the Sultan Murad IV. Coffee, regarded as a Muslim drink, was prohibited by Ethiopian Orthodox Christians until as late as 1889; it is now considered a national drink of Ethiopia for people of all faiths. Its early association in Europe with rebellious political activities led to its banning in England, among other places.

A contemporary example of coffee prohibition can be found in The Church of Jesus Christ of Latter-day Saints. The organization claims that it is both physically and spiritually unhealthy to consume coffee. This comes from the Mormon doctrine of health, given in 1833 by Mormon founder Joseph Smith in a revelation called the Word of Wisdom. It does not identify coffee by name, but includes the statement that "hot drinks are not for the belly," which has been interpreted to forbid both coffee and tea.

Quite a number of members of the Seventh-day Adventist Church also avoid caffeinated drinks. In its teachings, the Church requires members to avoid tea and coffee and other stimulants. Studies conducted on Adventists have shown a small but statistically significant association between coffee consumption and mortality from ischemic heart disease, other cardiovascular disease, all cardiovascular diseases combined, and all causes of death.

Health and pharmacology

Scientific studies have examined the relationship between coffee consumption and an array of medical conditions. Findings are contradictory as to whether coffee has any specific health benefits, and results are similarly conflicting regarding the negative effects of coffee consumption.

Overview of the more common effects of caffeine, a main active component of coffee

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." Various other studies have shown apparent reductions in the risks of 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 moderate drinkers of coffee (3-5 cups per day) had lower chances of developing dementia, in addition to Alzheimer's disease. It increases the risk of acid reflux and associated diseases. Some health effects of coffee are due to its caffeine content, as the benefits are only observed in those who drink caffeinated coffee while others appear to be due to other components. For example, the antioxidants in coffee prevent free radicals from causing cell damage.

Caffeine is the major coffee constituent which the coffee tolerance or intolerance depends on. In a healthy liver, the majority of caffeine is degraded by the hepatic microsomal enzymatic system. Caffeine is mostly degraded to paraxanthine substances, partially to 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 a majority of elderly people. Excessive amounts of coffee, however, can in many individuals cause very unpleasant, exceptionally even life-threatening side effects.

Coffee consumption can lead to iron deficiency anemia in mothers and infants. Coffee also interferes with the absorption of supplemental iron.

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. Many high end perfume shops now offer coffee beans to refresh the receptors between perfume tests.

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. Research suggests that drinking caffeinated coffee can cause a temporary increase in the stiffening of arterial walls. Coffee is no longer thought to be a risk factor for coronary heart disease. Some studies suggest 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. About 10% of people with a moderate daily intake (235 mg per day) reported increased depression and anxiety when caffeine was withdrawn, and about 15% of the general population report having stopped caffeine use completely, citing concern about health and unpleasant side effects.

Caffeine content:

Caffeine molecule:

Depending on the type of coffee and method of preparation, the caffeine content of a single serving can vary greatly. On average, a single cup of coffee (about 200 milliliters) or a single shot of espresso (about 30 mL) can be expected to contain the following amounts of caffeine:

Drip coffee: 115–175 mg (560–850 mg/L)
Espresso: 60 mg (2000 mg/L)
Brewed/Pressed: 80–135 mg (390–650 mg/L)
Instant: 65–100 mg (310–480 mg/L)
Decaf, brewed: 3–4 mg
Decaf, instant: 2–3 mg

ثورة ثقافية

الأربعاء، ١٨ يناير ٢٠١٢

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