Coffea arabica is a species of Coffea originally indigenous to the forests of the southwestern highlands of Ethiopia. It is also known as the "coffee shrub of Arabia", "mountain coffee" or "arabica coffee". Coffea arabica is believed to be the first species of coffee to be cultivated.
Wild plants grow to between 9 and 12 m (29 and 39 ft) tall, and have an open branching system; the leaves are opposite, simple elliptic-ovate to oblong, 6–12 cm (2.4–4.8 in) long and 4–8 cm (1.6–3.2 in) broad, glossy dark green. The flowers are white, 10–15 mm in diameter and grow in axillary clusters. The seeds are contained in a drupe (though commonly called a "cherry"; the plural form is simply "cherry"—used only when referring to the fruit of C. arabica—when referring to the actual cherry fruit, the appropriate plural is "cherries") 10–15 mm in diameter, maturing bright red to purple and typically contains two seeds (the coffee seeds).
Distribution and habitat
Originally found in the southwestern highlands of Ethiopia, Coffea arabica is now rare in its native state, and many populations appear to be mixed native and planted trees. It is common there as an understorey shrub. It has also been recovered from the Boma Plateau in South Sudan. C. arabica is also found on Mount Marsabit in northern Kenya, but it is unclear whether this is a truly native or naturalised occurrence. The species is widely naturalised in areas outside its native land, in many parts of Africa, Latin America, Southeast Asia, China, and assorted islands in the Caribbean and in the Pacific.
The conservation of the genetic variation of Coffea arabica relies on conserving healthy populations of wild coffee in the Afromontane rainforests of Ethiopia. Genetic research has shown coffee cultivation is threatening the genetic integrity of wild coffee because it exposes wild genotypes to cultivars. Nearly all of the coffee that has been cultivated over the past few centuries originated with just a handful of wild plants from Ethiopia, and today the coffee growing on plantations around the world contains less than 1 percent of the diversity contained in the wild in Ethiopia alone.
Cultivation and use
Arabica coffee’s first domestication in Ethiopia is obscure, however cultivation in Yemen is well documented by the 12th century.
Coffea arabica accounts for 75–80 percent of the world's coffee production.
C. arabica takes about seven years to mature fully, and does best with 1.0–1.5 meters (about 40–59 inches) of rain, evenly distributed throughout the year. It is usually cultivated between 1,300 and 1,500 m altitude, but there are plantations as low as sea level and as high as 2,800 m.
The plant can tolerate low temperatures, but not frost, and does best with an average temperature between 15 and 24 °C (59 and 75 °F). Commercial cultivars mostly only grow to about 5 m, and are frequently trimmed as low as 2 m to facilitate harvesting. Unlike Coffea canephora, C. arabica prefers to be grown in light shade.
Two to four years after planting, C. arabica produces small, white, highly fragrant flowers. The sweet fragrance resembles the sweet smell of jasmine flowers. Flowers opening on sunny days results in the greatest numbers of berries. This can be a curse, however, as coffee plants tend to produce too many berries; this can lead to an inferior harvest and even damage yield in the following years, as the plant will favour the ripening of berries to the detriment of its own health.
On well-kept plantations, overflowering is prevented by pruning the tree. The flowers only last a few days, leaving behind only the thick dark green leaves. The berries then begin to appear. These are as dark green as the foliage, until they begin to ripen, at first to yellow and then light red and finally darkening to a glossy deep red. At this point they are called “cherry” and are ready for picking.
The berries are oblong and about 1 cm long. Inferior coffee results from picking them too early or too late, so many are picked by hand to be able to better select them, as they do not all ripen at the same time. They are sometimes shaken off the tree onto mats, which means ripe and unripe berries are collected together.
The trees are difficult to cultivate and each tree can produce from 0.5 to 5.0 kg of dried beans, depending on the tree's individual character and the climate that season. The real prize of this cash crop are the beans inside. Each berry holds two locules containing the beans. The coffee beans are actually two seeds within the fruit; there is sometimes a third seed or one seed, a peaberry in the fruit at tips of the branches. These seeds are covered in two membranes; the outer one is called the "parchment coat" and the inner one is called the "silver skin".
On Java Island, trees are planted at all times of the year and are harvested year round. In parts of Brazil, however, the trees have a season and are harvested only in winter. The plants are vulnerable to damage in poor growing conditions (cold, low pH soil) and are also more vulnerable to pests than the C. robusta plant.
Arabica coffee production in Indonesia began in 1699. Indonesian coffees, such as Sumatran and Java, are known for heavy body and low acidity. This makes them ideal for blending with the higher acidity coffees from Central America and East Africa.
In Hawaii, coffee was formerly more widely grown than at present, and it persists after cultivation in many areas. In some valleys, it is a highly invasive weed. In the Udawattakele and Gannoruwa Forest Reserves near Kandy, Sri Lanka, coffee shrubs are also a problematic invasive.
It is expected that there may be a medium-term depletion of indigenous populations of arabica, due to projected global warming, based on IPCC modelling.
Gourmet coffees are almost exclusively high-quality mild varieties of arabica coffee, and among the finest arabica coffee beans in the world used for making espresso coffee are Jamaican Blue Mountain, Colombian Supremo, Tarrazú, Costa Rica, Guatemalan Antigua and Ethiopian Sidamo.
History and legend
According to legend, human cultivation of coffee began after goats in Ethiopia were seen mounting each other after eating the leaves and fruits of the coffee tree. In Ethiopia, people in some locales still drink an herbal tea made from the leaves of the coffee tree.
The first written record of coffee made from roasted coffee beans comes from Arab scholars, who wrote that it was useful in prolonging their working hours. The Arab innovation in Yemen of making a brew from roasted beans, spread first among the Egyptians and Turks, and later on found its way around the world.
Coffea arabica was first described by Antoine de Jussieu, who named it Jasminum arabicum after studying a specimen from the Botanic Gardens of Amsterdam. Linnaeus placed it in its own genus Coffea in 1737.
One strain of Ethiopian Coffea arabica naturally contains very little caffeine. While beans of normal C. arabica plants contain 12 milligrams of caffeine per gram of dry mass, these newly found mutants contain only 0.76 milligrams of caffeine per gram, but with all the taste of normal coffee.