Coffee
Coffee is a beverage, usually served hot, prepared from the roasted seeds of the coffee plant. These seeds are almost always called coffee beans, even though they are technically not beans.
Coffee has significant impacts on the economy, has possible health benefits, is featured at many social functions, has important environmental implications depending on how it is grown, and it has been at the forefront of fair trade programs. Coffee ranks as one of the world's major commodity crops and is the major export product of some countries. In fact, coffee ranks second only to petroleum in terms of legally-traded products worldwide.
Because most of the coffee producing and exporting nations are poorer countries, and coffee importing nations are the wealthier countries, coffee represents a product with the potential to alleviate the income disparity between these nations. Of course, while providing jobs for people in less developed nations, much of the wealth still ends up in the hands of middlemen and not the local farmers.
When the coffee plant is grown in a traditional manner, under the shade of a forest canopy and without pesticides, there is little environmental harm. However, the development of coffee varieties that requires a lot of sunlight and pesticide use has led to river pollution, deforestation, and soil erosion. While such coffee is more economical to produce and has greater yields, concern for long-term environmental sustainability has lead to calls for consumers to support the use of the more traditional methods.
Coffee plant
Coffea (the coffee plant) is a genus of ten species of flowering plants in the family Rubiaceae. They are shrubs or small trees, native to subtropical Africa and southern Asia. Seeds of this plant are the source of coffee. The seeds, called "coffee beans" in the trade, are widely cultivated in tropical countries in plantations for both local consumption and export to temperate countries.
When grown in the tropics, coffee is a vigorous bush or small tree easily grown to a height of 3–3.5 m (10–12 feet). It is capable of withstanding severe pruning. It cannot be grown where there is a winter frost. Bushes grow best at high elevations. To produce a maximum yield of coffee berries (800-1400 kg per hectare), the plants need substantial amounts of water and fertilizer.
There are several species of Coffea that may be grown for the beans, but Coffea arabica is considered to have the best quality. The other species (especially Coffea canephora (robusta)) are grown on land unsuitable for Coffea arabica. The tree produces red or purple fruits (drupes, coffee berries, or "coffee cherries"), which contain two seeds (the "coffee beans"). In about 5-10 percent of any crop of coffee cherries, the cherry will contain only a single bean, rather than the two usually found. This is called a “peaberry” and contains a distinctly different flavor profile to the normal crop, with a higher concentration of the flavors, especially acidity, present due to the smaller sized bean. As such, it is usually removed from the yield and either sold separately (such as in New Guinea Peaberry), or discarded.
The coffee tree will grow fruits after 3–5 years, for about 50–60 years (although up to 100 years is possible). The blossom of the coffee tree is similar to jasmine in color and smell. The fruit takes about nine months to ripen. Worldwide, an estimate of 15 billion coffee trees are growing on 100,000 km² of land.
Coffee is used as a food plant by the larvae of some Lepidoptera species including Dalcera abrasa, Turnip Moth, and some members of the genus Endoclita including E. damor and E. malabaricus.
Spent coffee grounds are a good fertilizer in gardens because of their high nitrogen content.
Coffee bean types
The two main species of the coffee plant used to produce the beverage are Coffea arabica and Coffee canephora (robusta). Coffee arabica is thought to be indigenous to Ethiopia and was first cultivated on the Arabian Peninsula. While more susceptible to disease, it is considered by most to taste better than Coffea canephora (robusta). Robusta, which contains about twice as much caffeine, can be cultivated in environments where arabica will not thrive. This has led to its use as an inexpensive substitute for arabica in many commercial coffee blends. Compared to arabica, robusta tends to be more bitter, with a telltale "burnt rubber" aroma and flavor. Good quality robustas are used as ingredients in some espresso blends to provide a better "crema" (foamy head), and to lower the ingredient cost. In Italy, many espresso blends are based on dark-roasted robusta.
Arabica coffees were traditionally named by the port they were exported from, the two oldest being Mocha, from Yemen, and Java, from Indonesia. The modern coffee trade is much more specific about origin, labeling coffees by country, region, and sometimes even the producing estate. Coffee aficionados may even distinguish auctioned coffees by lot number.
The largest coffee exporting nation remains Brazil, but in recent years the green coffee market has been flooded by large quantities of robusta beans from Vietnam. Many experts believe this giant influx of cheap green coffee led to the prolonged pricing crisis from 2001 to the present. In 1997 the "c" price of coffee in New York broke U.S. $3.00/pound, but by late 2001 it had fallen to U.S. $0.43/pound. Robusta coffees (traded in London at much lower prices than New York's Arabica) are preferred by large industrial clients (multinational roasters, instant coffee producers, etc.) because of their lower cost.
Coffee beans from two different places, or coffee varietals, usually have distinctive characteristics, such as flavor (flavor criteria includes terms such as "citrus-like" or "earthy"), caffeine content, body or mouthfeel, and acidity. These are dependent on the local environment where the coffee plants are grown, their method of process, and the genetic subspecies or varietal.
Economics of coffee
Coffee is second only to petroleum in importance in commodity trade. It is the primary export of many low-income countries in Latin America, Africa, and Asia providing 25 million persons with their income. On a global scale, some 500 million people utilize coffee directly or indirectly for their incomes.
The top ten coffee producers for 2005 were:
| Country | Production in Millions of Metric Tons | Percent of World Production |
|---|---|---|
| Brazil | 2.18 | 28.2% |
| Vietnam | 0.99 | 12.8% |
| Indonesia | 0.76 | 9.8% |
| Colombia | 0.68 | 8.8% |
| Mexico | 0.31 | 4.0% |
| India | 0.28 | 3.6% |
| Ethiopia | 0.26 | 3.3% |
| Guatemala | 0.22 | 2.8% |
| Honduras | 0.19 | 2.5% |
| Uganda | 0.19 | 2.5% |
The top ten coffee importers for 2004/2005 are:
| Country | Percent of World Imports |
|---|---|
| U.S.A. | 20.0% |
| Germany | 15.1% |
| Japan | 6.2% |
| Italy | 6.1% |
| France | 5.3% |
| Spain | 3.6% |
| Belgium/Luxembourg | 3.5% |
| United Kingdom | 2.9% |
| Netherlands | 2.8% |
| Poland | 2.5% |
The top ten coffee per capita consumption
| Country | Cups per Capita |
|---|---|
| Finland | 1,686 |
| Denmark | 1,374 |
| Norway | 1,372 |
| Belgium | 1,354 |
| Sweden | 1,249 |
| Austria | 1,065 |
| Switzerland | 1,017 |
| Germany | 988 |
| Netherlands | 915 |
| France | 831 |
With over 400 billion cups consumed every year, coffee is the world's most popular beverage. Worldwide, 25 million small producers rely on coffee for a living. For instance, in Brazil alone, where almost a third of all the world's coffee is produced, over 5 million people are employed in the cultivation and harvesting of over 3 billion coffee plants. It is a much more labor-intensive culture than alternative cultures of commodities such as soy, sugar cane, wheat, or cattle, as it is not subject to automation and requires constant attention.
Coffee is also bought and sold as a commodity on the New York Coffee, Sugar, and Cocoa Exchange. This is where coffee futures contracts are traded, which are a financial asset involving a standardized contract for the future sale or purchase of a unit of coffee at an agreed price.
According to the Composite Index of the London-based coffee export country group International Coffee Organization, the monthly coffee price averages in international trade had been well above 100 U.S. cents/pound during in the 1970s/1980s, but then declined during the late 1990s reaching a minimum in September 2001 of just 41.17 U.S. cents per pound, and remained low until 2004. The reasons for this decline included the expansion of Brazilian coffee plantations and Vietnam's entry into the market in 1994, when the United States trade embargo against Vietnam was lifted. The market awarded the more efficient Vietnamese coffee suppliers with trade and resulted in less efficient coffee bean farmers in many countries such as Brazil, Nicaragua, and Ethiopia not being able to live off of their products; many were forced to quit the coffee bean production and move into slums in the cities (Mai 2006).
Ironically, the decline in the ingredient cost of green coffee, while not the only cost component of the final cup being served, was paralleled by the rise in popularity of Starbucks and thousands of other specialty cafés, which sold their beverages at unprecedented high prices. According to the Specialty Coffee Association of America, in 2004 16 percent of adults in the United States drank specialty coffee daily; the number of retail specialty coffee locations, including cafés, kiosks, coffee carts, and retail roasters, amounted to 17,400 and total sales were $8.96 billion in 2003.
In 2005, however, the coffee prices rose, with the above-mentioned ICO Composite Index monthly averages between 78.79 (September) and 101.44 (March) U.S. cents per pound. This rise was likely caused by an increase in consumption in Russia and China, as well as a harvest that was about 10 to 20 percent lower than that in the record years before. This allowed many coffee bean farmers to be able to live off their products, but not all of the extra-surplus trickled down to them, because rising petroleum prices made the transportation, roasting, and packaging of the coffee beans more expensive (Mai 2006).
A number of classifications are used to label coffee produced under certain environmental or labor standards. For instance, bird-friendly or shade-grown coffee is produced in regions where natural shade (canopy trees) is used to shelter coffee plants during parts of the growing season. Organic coffee is produced under strict certification guidelines, and is grown without the use of potentially harmful artificial pesticides or fertilizers. Fair trade coffee is produced by small coffee producers; guaranteeing for these producers a minimum price. TransFair USA is the primary organization overseeing Fair Trade coffee practices in the United States, while the Fairtrade Foundation does so in the United Kingdom.
Etymology and history
The word coffee entered English in 1598 via Italian caffè, via Turkish kahve, from Arabic qahwa. Its ultimate origin is uncertain, there being several legendary accounts of the origin of the drink. One possible origin is the Kaffa region in Ethiopia, where the plant originated (its native name there being bunna).
Coffee has been around since at least 800 B.C.E., originating in Africa and popularized throughout the Muslim world from 1000 C.E. Coffee beans were first exported from Ethiopia to Yemen. One legendary account is that of the Yemenite Sufi mystic named Shaikh ash-Shadhili. When traveling in Ethiopia, he observed goats of unusual vitality and, upon trying the berries that the goats had been eating, experienced the same effect. A similar myth ascribes the discovery to an Ethiopian goatherd named Kaldi. Qahwa originally referred to a type of wine, and need not be the name of the Kaffa region.
Consumption of coffee was outlawed in Mecca in 1511 and in Cairo in 1532, but in the face of its immense popularity, the decree was later rescinded. In 1554, the first coffeehouse in Istanbul opened.
Largely through the efforts of the British and Dutch East India companies, coffee became available in Europe no later than the sixteenth century, according to Leonhard Rauwolf's 1583 account. The first coffeehouse in England was set up in Oxford by a man named Jacob or Jacobs, a Turkish Jew, in 1650. The first coffeehouse in London was opened two years later in St. Michael's Alley in Cornhill. The proprietor was Pasqua Rosée, the Ragusan (Italian city) servant of a trader in Turkish goods named Daniel Edwards, who imported the coffee and assisted Rosée in setting up the establishment. The coffeehouse spread rapidly in Europe and America after that, with the first coffeehouses opening in Boston in 1670, and in Paris in 1671. By 1675, there were more than 3,000 coffeehouses in England.
Women were not allowed in coffeehouses, and in London, the anonymous 1674 "Women's Petition Against Coffee" complained:
- "…the Excessive Use of that Newfangled, Abominable, Heathenish Liquor called COFFEE […] has […] Eunucht our Husbands, and Crippled our more kind Gallants, that they are become as Impotent, as Age." [1]
Legend has it that the first coffeehouse opened in Vienna in 1683 after the Battle of Vienna, taking its supplies from the spoils left behind by the defeated Turks. The officer who received the coffee beans, Polish military officer Franciszek Jerzy Kulczycki, opened the first coffee house in Vienna and helped popularize the custom of adding sugar and milk to the coffee. Another more credible story is that the first coffeehouses were opened in Krakow in the sixteenth or seventeenth century because of closer trade ties with the East, most notably the Turks. The first coffee plantation in the New World was established in Brazil in 1727, and this country, like most others cultivating coffee as a commercial commodity, relied heavily on slave labor from Africa for its viability until abolition in 1888.
In 1763, Pope Clemente VII was asked to forbid coffee as the “devil’s beverage.” The Pontiff decided to try it first and declared, “This beverage is so delicious that it would be a sin to let only misbelievers drink it! Let’s defeat Satan by blessing this beverage, which contains nothing objectionable to a Christian.” With this endorsement, the coffee trade was assured success.
Coffee also got another huge endorsement from the American Revolution following the Boston Tea Party. Patriots began drinking coffee instead of tea as a symbol of their struggle for freedom. Today, coffee is consumed more than any beverage in the United States except water. One can find “coffee breaks” in the work place, “coffee hour” following religious services, and coffee houses for socialization and entertainment.
One interesting and notable exception to the American love for coffee is that the Church of Jesus Christ of Latter Day Saints (the Mormons) prohibits tea and coffee from consumption by their members.
For many decades in the nineteenth and early twentieth centuries, Brazil was the biggest producer and virtual monopolist in the trade, until a policy of maintaining high prices opened opportunities to other growers, like Colombia, Guatemala, and Indonesia.
Health and pharmacology of coffee
Coffee is consumed in large part not simply because of taste, but because of the effect it has on those who drink it.
Coffee as a stimulant
Coffee contains caffeine, which acts as a stimulant. For this reason, it is often consumed in the morning, and during working hours. Students preparing for examinations with late night "cram sessions" use coffee to maintain their concentration. Many office workers take a "coffee break" when their energy is diminished.
Recent research has uncovered additional stimulating effects of coffee that are not related to its caffeine content. Coffee contains an as yet unknown chemical agent that elicits the production of cortisone and adrenaline, two stimulating hormones.
For occasions when one wants to enjoy the flavor of coffee with less stimulation, decaffeinated coffee (also called “decaf”) is available. This is coffee from which most of the caffeine has been removed. This may be done by the Swiss water process (which involves the soaking of raw beans to absorb the caffeine), or by the use of a chemical solvent, such as trichloroethylene ("tri"), or the more popular methylene chloride. Another solvent used is ethyl acetate; the resultant decaffeinated coffee is marketed as "natural decaf" due to ethyl acetate being naturally present in fruit. Extraction with supercritical carbon dioxide has also been employed. Decaffeinated coffee usually loses some flavor over normal coffees and tends to be more bitter. There are also tisanes that resemble coffee in taste but contain no caffeine (see below).
Caffeine dependency and withdrawal symptoms are well-documented; see caffeine for more on the pharmacological effects of caffeine.
There have been cases all over the world of people who take far too much coffee in their drink (anywhere between 10-50 tablespoon's worth), and have experienced side effects similar to that of the illegal drug cocaine.
Benefits
There are many claims to the health benefits of drinking coffee.
Some of the major health benefit claims include:
- A moderate amount (two cups) of coffee can assist with short-term memory and can thus increase the probability to help a person be more alert for better learning.
- In the workplace, a moderate amount of coffee can reduce fatigue and thus reduce the probability of accidents. (see: http://www.positivelycoffee.org/topic_workplace_references.aspx)
- Coffee contains antioxidants that have been found to help reduce risks for heart disease with only two to four cups per day consumption.
- Some studies have indicated that coffee may help in the prevention of liver disease. (See http://www.positivelycoffee.org/topic_liver_enzymes.aspx)
- Studies indicate that type 2 diabetes is lower among those with moderate coffee consumption, and that coffee consumption may reduce the risk of gallstones, the development of colon cancer, and the risk of Parkinson disease. (see: http://www.health.harvard.edu/press_releases/coffee_health_risk.htm
Coffee increases the effectiveness of pain killers—especially migraine medications—and can rid some people of asthma. For this reason, some aspirin producers also include a small dose of caffeine in the pill. Some of the beneficial effects of coffee consumption may be restricted to one sex, for instance it has been shown to reduce the occurrence of gallstones and gallbladder disease in men. Coffee intake may reduce one's risk of diabetes mellitus type 2 by up to half. While this was originally noticed in patients who consumed high amounts (seven cups a day), the relationship was later shown to be linear (Salazar-Martinez 2004).
Coffee can also reduce the incidence of cirrhosis of the liver and prevent colon and bladder cancers. Coffee can reduce the risk of hepatocellular carcinoma, a variety of liver cancer (Inoue 2005). Also, coffee reduces the incidence of heart disease, though whether this is simply because it rids the blood of excess fat or because of its stimulant effect is unknown. At the annual meeting of the American Chemical Society in Washington, D.C., on August 28, 2005, chemist Joe Vinson of the University of Scranton presented his analysis showing that for Americans, who as a whole do not consume large quantities of fresh fruits and vegetables, coffee represents by far the largest source of valuable antioxidants in the diet.
Coffee contains the anticancer compound methylpyridinium. This compound is not present in significant amounts in other food materials. Methylpyridinium is not present in raw coffee beans but is formed during the roasting process from trigonellin, which is common in raw coffee beans. It is present in both caffeinated and decaffeinated coffee, and even in instant coffee.
Coffee is also a powerful stimulant for peristalsis and is sometimes considered to prevent constipation; it is also a diuretic. However, coffee can also cause loose bowel movements.
Many people drink coffee for its ability to increase short-term recall and increase IQ. It also changes the metabolism of a person so that their body burns a higher proportion of lipids to carbohydrates, which can help athletes avoid muscle fatigue.
Some of these health effects are realized by as little as four cups a day (24 U.S. fluid ounces, 700 mL), but others occur at five or more cups a day (32 U.S. fl. oz or 0.95 L or more).
Some controversy over these effects exists, since by its nature, coffee consumption is associated with other behavioral variables. Therefore it has been variously suggested that the cognitive effects of caffeine are limited to those who have not developed a tolerance, or to those who have developed a tolerance and are caffeine-deprived.
Practitioners in alternative medicine often recommend coffee enemas for "cleansing of the colon" due to its stimulus of peristalsis, although mainstream medicine has not proved any benefits of the practice.
Risks
Many notable effects of coffee are related to its caffeine content.
Many coffee drinkers are familiar with "coffee jitters," a nervous condition that occurs when one has had too much caffeine. Coffee can also increase blood pressure among those with high blood pressure, but follow-up studies showed that coffee still decreased the risk of dying from heart disease in the aggregate. Coffee can also cause insomnia in some, while paradoxically it helps a few sleep more soundly. It can also cause anxiety and irritability, in some with excessive coffee consumption, and some as a withdrawal symptom.
There are also gender-specific effects of coffee. In some PMS (pre-menstral syndrome) sufferers, it increases the symptoms. It can also reduce fertility in women, and may increase the risk of osteoporosis in postmenopausal women.
There may be risks to a fetus if a pregnant woman drinks substantial amounts of coffee (such as eight or more cups a day; that is, 48 U.S. fluid ounces or 1.4 L or more). A February 2003 Danish study of 18,478 women linked heavy coffee consumption during pregnancy to significantly increased risk of stillbirths (but no significantly increased risk of infant death in the first year). "The results seem to indicate a threshold effect around four to seven cups per day," the study reported. Those who drank eight or more cups a day (48 U.S. fl oz or 1.4 L) were at 220 percent increased risk compared with nondrinkers. This study has not yet been repeated, but has caused some doctors to caution against excessive coffee consumption during pregnancy.
Decaffeinated coffee is occasionally regarded as a potential health risk to pregnant women, due to the high incidence of chemical solvents used to extract the caffeine. These concerns may have little or no basis, however, as the solvents in question evaporate at 80–90° C, and coffee beans are decaffeinated before roasting, which occurs at approximately 200° C. As such, these chemicals, namely trichloroethane and methylene chloride, are present in trace amounts at most, and neither pose a significant threat to unborn children. Women still worried about chemical solvents in decaffeinated coffee should opt for beans that use the Swiss water process, where no chemicals other than water are used, although higher amounts of caffeine remain.
The American Journal of Clinical Nutrition published a study in 2004 that tried to discover why the beneficial and detrimental effects of coffee conflict. The study concluded that consumption of coffee is associated with significant elevations in biochemical markers of inflammation. This is a detrimental effect of coffee on the cardiovascular system, which may explain why coffee has so far only been shown to help the heart at levels of four cups (20 fluid ounces or 600 mL) or fewer per day.
Coffee in large amounts has been found to be associated with increased heart rate, increased blood pressure, and occasional irregular heart beat.
Processing
Much processing and human labor is required before coffee berries and its seed can be processed into roasted coffee with which most Western consumers are familiar. Coffee berries must be picked, defruited, dried, sorted, and sometimes aged. All coffee is roasted before being consumed.
Roasting has a great degree of influence on the taste of the final product. Once the raw ("green") coffee beans arrive in their destination country, they are roasted. This darkens their color and alters the internal chemistry of the beans and therefore their flavor and aroma. Blending can occur before or after roasting and is often performed to ensure a consistent flavor. Once the beans are roasted, they become much more perishable.
Problems of maintaining quality during bean production
Achieving consistently high quality milled beans is not easy. Problems include:
- Pests on the bushes (e.g., in Hawaii, scale insects and coconut mealy bugs)
- Poor pruning regimes (e.g., too many verticals that allow the bush to attempt too much and so produce inferior cherries)
- Poor fertilizer regimes (e.g., too little iron or insufficient nutriment for what are demanding plants)
- Bad picking (e.g., picking all the berries on a branch rather than those that are bright red, or picking the berries very late)
- Bad fermentation that produces unpleasant taints in the flavor
- Dilution of superior tasting beans with cheaper beans
When conditions permit, coffee bushes fruit aggressively, and the berries will develop at the expense of the rest of the bush. The consequent sugar consumption can produce die-back (death of leaves and branches). Die-back can be severe and can damage not just the current year's production but also the next year's production, which is borne on growth during the current year.
Commercial operators come under a variety of pressures to cut costs and maximize yield. Arguably, better flavors will be produced when the coffee is grown in organic conditions. Some people who grow organically do so primarily to obtain the premium prices organic beans command, an alternative strategy to increase profits.
Preparing
The processing of coffee typically refers to the agricultural and industrial processes needed to deliver whole roasted coffee beans to the consumer. In order to turn this into a beverage, some preparation is typically necessary. The particular steps needed vary with the type of coffee desired, and with the raw material being worked with (e.g., pre-ground vs. whole bean). Typically, coffee must be ground to varying coarseness depending on the brewing method. Once brewed, it may be presented in a variety of ways: on its own, with or without sugar, with or without milk or cream, hot or cold, and so on.
Quick coffee
A number of products are sold for the convenience of consumers who do not want to prepare their own coffee. Instant coffee has been dried into soluble powder or granules, which can be quickly dissolved in hot water for consumption. Canned coffee is a beverage that has been popular in Asian countries for many years, particularly in Japan and South Korea. Vending machines typically sell a number of varieties of canned coffee, available both hot and cold. To match with the often-busy life of Korean city dwellers, companies mostly have canned coffee with a wide variety of tastes. Japanese convenience stores and groceries also have a wide availability of plastic-bottled coffee drinks, which typically are lightly sweetened and pre-blended with milk. In the United States, Starbucks is a retail outlet that sells a number of prepared cold coffee drinks in both bottles and cans. Lastly, liquid coffee concentrate is 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 cents a cup to produce. The machines used to process it can handle up to 500 cups an hour, or 1,000 if the water is preheated.
Social aspects of coffee
The United States is the largest market for coffee, followed by Germany. The Nordic countries consume the most coffee per capita, with Finland, Norway, and Denmark trading the top spot depending on the year. However, consumption has also vastly increased in the United Kingdom in recent years.
Coffee is so popular in the Americas, the Middle East, and Europe that many restaurants specialize in coffee; these are called "coffeehouses" or "cafés." Most cafés also serve tea, sandwiches, pastries, and other light refreshments (some of which may be dunked into the drink. Some shops are miniature cafés that specialize in coffee-to-go for hurried travelers, who may visit these on their way to work. Some provide other services, such as wireless internet access, for their customers.
In some countries, notably in northern Europe, coffee parties are a popular form of entertaining. Besides coffee, the host or hostess at the coffee party also serves cake and pastries, hopefully homemade.
Because of the stimulant properties of coffee and because coffee does not adversely impact higher mental functions, coffee is strongly associated with white-collar jobs and office workers. Social habits involving coffee in offices include the morning chat over coffee and the coffee break. Contemporary advertising tends to equate the term "coffee break" with rest and relaxation, despite coffee's stimulant role.
ReferencesISBN links support NWE through referral fees
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- Joffe-Walt, B., and O. Burkeman. 2005. Coffee trail—from Ethiopian village of Choche to London coffee shop. The Guardian September 16, 2005.
- Koppelstaeter, F. et al. 2005. Influence of Caffeine Excess on Activation Patterns in Verbal Working Memory, Conference paper presented at the Radiological Society of North America, November 30, 2005.
- Lunde, P., and J. Mandaville. 1973. Wine of Arabia. Saudi Aramco World 24(5) (September/October 1973).
- Mai, M. 2006. Boom für die Bohnen in Jungle World 1 (January 4, 2006). ISSN 1613-0766.
- Pendergrast, M. 1999. Uncommon Grounds: The History of Coffee and How It Transformed Our World. Basic Books. ISBN 0465054676
- Salazar-Martinez E., W.C. Willet, A. Ascherio, J. E. Manson, M. F. Leitzmann, M. J. Stampfer, and F. B. Hu. 2004. Coffee consumption and risk for type 2 diabetes mellitus. Ann Intern Med 140: 1-8.
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