1. Introduction 1. 1 fig Coffee is a brewed beverage with a distinct aroma and flavor, prepared from the roasted seeds of the Coffea plant. The seeds are found in coffee “cherries”, which grow on trees cultivated in over 70 countries, primarily in equatorial America, Southeast, South Asia and Africa. Green (unroasted) coffee is one of the most traded agricultural commodities in the world.
Coffee is slightly acidic (pH 5. 0–5. 1) and can have a stimulating effect on humans because of its caffeine content. It is one of the most consumed drinks in the world.
Wild coffee’s energizing effect was likely first discovered in the northeast region of Ethiopia. Coffee cultivation first took place in southern Arabia; the earliest credible evidence of coffee-drinking appears in the middle of the 15th century in the Sufi shrines of Yemen. In East Africa and Yemen, coffee was used in native religious ceremonies that were in competition with the Christian Church. As a result, the Ethiopian Church banned its secular consumption until the reign of Emperor Menelik II of Ethiopia.
The beverage was also 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 seeds, are produced by several species of small evergreen bush of the genus Coffea. The two most commonly grown are also the most 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, before being 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. Consequently, organic coffee is an expanding market.
Many studies have examined the health effects of coffee, and whether the overall effects of coffee consumption are positive or negative has been widely disputed. The method of brewing coffee has been found to be important in relation to its effects on health. For instance, preparing coffee in a French press leaves more oils in the drink compared with coffee prepared with a paper coffee filter. This might raise the drinker’s level of “bad cholesterol. ” Etymology The first reference to “coffee” in the English language is in the form chaoua and dates to 1598.
In English and other European languages, coffee derives from the Ottoman Turkish kahve, via the Italian caffe. 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??? qaha, 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 south western 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 bun. History Ethiopian ancestors of today’s Oromo people were believed to have been the first to recognize the energizing effect of the coffee plant, though 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 goatherder who discovered coffee, did not appear in writing until 1671 and is probably apocryphal.
Other accounts attribute the discovery of coffee to Sheik Omar. According to the ancient chronicle (preserved in the Abd-Al-Kadir manuscript), Omar, who was known for his ability to cure the sick through prayer, was once exiled from Mocha, Yemen to a desert cave near Ousab. Starving, Omar chewed berries from nearby shrubbery, but found them to be bitter. He tried roasting the seeds to improve the flavor, but they became hard. He then tried boiling them to soften the seed, which resulted in a fragrant brown liquid.
Upon drinking the liquid Omar was revitalized and sustained for days. As stories of this “miracle drug” reached Mocha, Omar was asked to return and was made a saint. 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 15th century, in the Sufi monasteries around Mokha in Yemen. It was here in Arabia that coffee seeds 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 seeds were first exported from Ethiopia to Yemen. Yemeni traders brought coffee back to their homeland and began to cultivate the seed. 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 seeds 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. —Leonard Rauwolf, Reise in die Morgenlander (in German).
From the Middle East, 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 East India Company was the first to import coffee on a large scale. 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, 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 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. The 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 Sao 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 developing 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. World production In 2011 Brazil was the world leader in production of green coffee, followed by Vietnam, Indonesia and Colombia. Arabica coffee seeds are cultivated in Latin America, eastern Africa, Arabia, or Asia. Robusta coffee seeds are grown in western and central Africa, throughout Southeast Asia, and to some extent in Brazil.
Seeds 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. 2011 Top twenty green coffee producers| Rank| Country| Tonnes| Bags x1000| 1| Brazil| 2,609,040| 43,484| 2| Vietnam| 1,200,000| 20,000| 3| Indonesia| 495,000| 8,250| 4| Colombia| 468,000| 7,800| 5| Ethiopia| 390,000| 6,500|.
6| Peru| 326,580| 5,443| 7| India| 319,980| 5,333| 8| Honduras| 270,000| 4,500| 9| Mexico| 258,000| 4,300| 10| Guatemala| 225,000| 3,750| 11| Uganda| 192,720| 3,212| 12| Nicaragua| 126,000| 2,100| 13| Costa Rica| 107,940| 1,799| 14| Ivory Coast| 96,000| 1,600| 15| Papua New Guinea| 84,900| 1,415| 16| El Salvador| 70,500| 1,175| 17| Cambodia| 64,980| 1,083| 18| Ecuador| 64,500| 1,075| 19| Democratic Republic of the Congo| 63,360| 1,056| 20| Venezuela| 60,000| 1,000| Total| World| 7,875,180| 131,253| 1. 1 (table) Biology 1. 2 fig (Illustration of Coffea arabica plant and seeds).
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’) andC. arabica. C. arabica, the 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. 2. Coffee Production 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. 2. 1 fig -Coffee sorting in Dutch East Indies (now Indonesia). 2.
2 fig – Coffee berries from Kerala, India Then they are sorted by ripeness and color and most often the flesh of the berry is removed, usually by machine, and the seeds are fermented to remove the slimy layer of mucilage still present on the seed. When the fermentation is finished, the seeds 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 seeds 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 seeds, though this is generally in places where the humidity is very high.
Some coffee undergoes a peculiar process, such as kopi luwak. It is made from the seeds of coffee berries which have been eaten by the Asian Palm Civet and other related civets, passing through its digestive tract. This process resulted in coffee seeds with much less bitterness, widely noted as the most expensive coffee in the world with prices reaching $160 per pound. Roasting 2. 3 fig – Roasted coffee seeds 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 seed both physically and chemically. The seed decreases in weight as moisture is lost and increases in volume, causing it to become less dense. The density of the seed also influences the strength of the coffee and requirements for packaging. The actual roasting begins when the temperature inside the seed reaches approximately 200 °C (392 °F), though different varieties of seeds differ in moisture and density and therefore roast at different rates.
During roasting, caramelization occurs as intense heat breaks down starches, changing them to simple sugars that begin to brown, which alters the color of the seed. 2. 4 fig – The appearance of unroasted, green coffee seeds. 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, caffeol, is created at about 200 °C (392 °F), which is largely responsible for coffee’s aroma and flavor. Grading the roasted seeds.
Depending on the color of the roasted seeds 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 seeds 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 The degree of roast has an effect upon coffee flavor and body.
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 seed after processing. Chaff is usually removed from the seeds by air movement, though a small amount is added to dark roast coffees to soak up oils on the seeds. Decaffeination 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 soaking the green seeds 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. Storage Once roasted, coffee seeds must be stored properly to preserve the fresh taste of the seed. Ideally, the container must be airtight and kept in a cool, dry and dark place.
In order of importance: air, moisture, heat, and light are the environmental factors responsible for deteriorating flavor in coffee seeds. 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. In 1931, a method of vacuum packed cans of coffee was introduced, in which the roasted coffee was packed, 99% of the air was removed and the coffee in the can could be stored indefinitely until the can was opened.
Today this method is in mass use for coffee in a large part of the world. Brewing 2. 5 fig – Espresso brewing, showing desirable dark reddish-brown crema Coffee seeds must be ground and brewed to create a beverage. The criteria for choosing a method include flavor and economy. Almost all methods of preparing coffee require the seeds to be ground and mixed with hot water long enough to extract the flavor, but without over extraction that draws out bitter compounds. The spent grounds are removed and the liquid is consumed.
There are many brewing variations such as the fineness of grind, the ways in which the water extracts the flavor, additional flavorings (sugar, milk, spices), and spent ground separation techniques. 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). The roasted coffee seeds 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 seeds can be ground at home immediately before consumption.
It is also possible, though uncommon; to roast raw seeds at home. Coffee seeds may be ground in several ways. A burr grinder uses revolving elements to shear the seed; a blade grinder cuts the seeds with blades moving at high speed; and a mortar and pestle crushes the seeds. For most brewing methods, a burr grinder is deemed superior because the grind is more even and the grind size can be adjusted. 2. 6 fig – (An Ethiopian woman preparing coffee at a traditional ceremony. She roasts, crushes and brews the coffee on the spot. ) 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 pressurized. 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 seeds 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 briki.
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 using 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. Coffee may be brewed by steeping in a device such as a French press (also known as a cafetiere, coffee press or coffee plunger). 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. 95% of the caffeine is released from the coffee seeds within the first minute of brewing. 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 reddish-brown foam called crema that floats on the surface. Other pressurized water methods include the moka pot and vacuum coffee maker. Cold brew coffee is made by steeping coarsely ground seeds in cold water for several hours, then filtering them. 
This results in a brew lower in acidity than most hot-brewing methods. Serving 2. 7 fig Presentation can be an integral part of coffeehouse service, as illustrated by the common rosetta design layered into this latte. Once brewed, coffee may be served in a variety of ways. Drip-brewed, percolated, or French-pressed/cafetiere coffee may be served as white coffee with a dairy product such as milk or cream, or dairy substitute, or as black coffee with no such addition. 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 Caffe Americano. Reversely, long black is made by pouring espresso in water, which retains the crema compared to Caffe Americano. Milk is added in various forms to espresso: steamed milk makes a caffe latte, equal parts steamed milk and milk froth make a cappuccino, and a dollop of hot foamed milk on top creates a caffe macchiato. The use of steamed milk to form patterns such as hearts or maple leaves is referred to as latte art.
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 Kahlua, and Tia Maria. Coffee is also sometimes used in the brewing process of darker beers, such as a stout or porter. Instant coffee 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 Nescafe being 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, South Korea, and Taiwan.
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 can process up to 500 cups an hour or 1,000 if the water is preheated. 3. Coffee beans A coffee bean is a seed of the coffee plant. It is the pit inside the red or purple fruit often referred to as a cherry. Even though they are seeds, they are incorrectly referred to as ‘beans’ because of their resemblance to true beans. The fruits – coffee cherries or coffee berries – most commonly contain two stones with their flat sides together. A small percentage of cherries contain a single seed, instead of the usual two. This is called a peaberry.
Like Brazil nuts (a seed) and white rice, coffee seeds consist mostly of endosperm. The two most economically important varieties of coffee plant are the Arabica and the Robusta; 75-80% of the coffee produced worldwide is Arabica and 20% is Robusta. Arabica seeds consist of 0. 8-1. 4% caffeine and Robusta seeds consist of 1. 7-4% caffeine. As coffee is one of the world’s most widely consumed beverages, coffee seeds are a major cash crop, and an important export product, counting for over 50% of some developing nations’ foreign exchange earnings.
The United States imports more coffee than any other nation. In 2009 the average person in the United States consumed 4. 09 kg (9 lbs) of coffee. Cultivation of the coffee seed originated in Ethiopia, in approximately 850 C. E. Farming of the coffee plant then spread to the rest of Arabia, where it was first mentioned in writing around 900 C. E. The Yemenites guarded it carefully, but some plants were eventually smuggled out to the Dutch, who kept a few plants for gardens in the Netherlands.
The Americas were first introduced to the plants around 1723. South America is now responsible for approximately 45% of the world’s total coffee exports. Most of this coffee is made in Brazil. Significant dates * First cultivation in Europe (also first cultivation outside of east Africa/Arabia) – 1616 * First cultivation in India (Malabar) – late 1600s * First cultivation in Java – 1699 * First cultivation in Caribbean (Cuba, Haiti, Jamaica, Santo Domingo, Puerto Rico) – 1715–1730 * First cultivation in South America – 1730.
* First cultivation in Dutch East Indies – 1720 * Roasted seeds first sold on retail market (Pittsburgh) – 1865 * Important spray-drying techniques developed in 1950s Coffee plant The coffee tree averages from 5–10 m (16–33 ft) in height. As the tree gets older, it branches less and less and bears more leaves and fruit. The tree typically begins to bear fruit 3–4 years after being planted, and continues to produce for 10–20 more years, depending on the type of plant and the area. Coffee plants are grown in rows several feet apart.
Some farmers plant fruit trees around them or plant the coffee on the sides of hills, because they need specific conditions to flourish. Ideally, Arabica coffee seeds are grown at temperatures between 15–24 °C (59–75 °F) and Robusta at 24–30 °C (75–86 °F) and receive between 15–30 cm (5. 9–12 in) of rainfall per year. Heavy rain is needed in the beginning of the season when the fruit is developing, and less late in the season as it ripens. The harvesting period can be anywhere from three weeks to three months, and in some places the harvesting period continues all year round.
Content of green coffee seeds The term “green coffee seed” refers to unroasted mature or immature coffee seeds. These have been processed by wet or dry methods for removing the outer pulp and mucilage, and have an intact wax layer on the outer surface. When immature, they are green. When mature, they have a brown to yellow or reddish color, and typically weigh 300 to 330 mg per dried coffee seed. Nonvolatile and volatile compounds in green coffee seeds, such as caffeine, deter many insects and animals from eating them.
Further, both nonvolatile and volatile compounds contribute to the flavor of the coffee seed when it is roasted. Nonvolatile nitrogenous compounds (including alkaloids, trigonelline, proteins and free amino acids) and carbohydrates are of major importance in producing the full aroma of roasted coffee, and for its biological action. * Nonvolatile alkaloids 3. 1 fig – Coffea canephora green seeds on a tree in Goa, India. Caffeine (1,3,7-trimethyl-xanthine) is the alkaloid most present in green and roasted coffee seeds.
The content of caffeine is between 1. 0% and 2. 5% by weight of dry green coffee seeds. The content of caffeine does not change during maturation of green coffee seeds. Lower concentrations of theophylline, theobromine, paraxanthine, liberine, and methylliberine can be found. The concentration of theophylline, an alkaloid noted for its presence in green tea, is reduced during the roasting process, usually about 15 minutes at 230 °C (446 °F), whereas the concentration of most other alkaloids are not changed.
The solubility of caffeine in water increases with temperature and with the addition of chlorogenic acids, citric acid, or tartaric acid, all of which are present in green coffee seeds. For example, 1 g (0. 035 oz) caffeine dissolves in 46 ml (1. 6 US fl oz) of water at room temperature, and 5. 5 ml (0. 19 US fl oz) at 80 °C (176 °F). The xanthine alkaloids are odorless, but have a bitter taste in water, which is masked by organic acids present in green coffee, however. Trigonelline (N-methyl-nicotinate) is a derivative of vitamin B6 that is not as bitter as caffeine.
In green coffee seeds, the content is between 0. 6% and 1. 0%. At a roasting temperature of 230 °C (446 °F), 85% of the trigonelline is degraded to nicotinic acid, leaving small amounts of the unchanged molecule in the roasted seeds. In green coffee seeds, trigonelline is synthesized from nicotinic acid (pyridinium-3-carboxylic acid) by methylation from methionine, a sulfur-containing amino acid. Mutagenic activity of trigonelline has been reported.