Arabica coffee

Coffea arabica is an evergreen shrub or small tree that grows two to five metres tall in cultivation, with dark glossy leaves and clusters of fragrant white flowers. The fruit, called a cherry, ripens to bright red, and each holds two flat-faced seeds, the coffee beans, enclosed in a papery parchment and sweet pulp. Occasionally a single round seed, called a peaberry, forms.

Green beans are pale grey-green and grassy; roasting turns them brown and develops aroma, sugars and bitterness. Arabica is generally described as sweeter, more aromatic and more acidic than robusta, with flavours that range from fruity to chocolatey depending on origin and processing. Beans are sold green, roasted whole, ground or as instant.

Coffea arabica is native to the highland forests of southwestern Ethiopia and neighbouring regions of South Sudan, where wild coffee still grows. It is a tetraploid species believed to have arisen from natural hybridisation between two other coffee species, and it is largely self-pollinating, which results in low genetic diversity among cultivated plants.

The species name arabica reflects the cultivation of coffee in Arabia, where it was first grown commercially in Yemen. The English word coffee comes via Dutch, Italian and Turkish from Arabic qahwa.

A popular legend tells of an Ethiopian goatherd named Kaldi who noticed his goats dancing after eating coffee cherries, but the story is not documented. What is better established is that coffee drinking was practised by Sufi communities in Yemen by the 15th century, who used the drink to stay awake during night devotions. From Yemen, the port of Mocha shipped beans around the Islamic world, and coffeehouses became centres of conversation in Cairo, Istanbul and Mecca.

Coffee reached Europe in the 17th century through Venice and other trading cities, and coffeehouses became places of news and commerce in London, Paris and Vienna. The Dutch broke the Arabian monopoly by taking plants to Java, and the French and Portuguese spread coffee to the Caribbean, Brazil and Latin America. In the 19th century, Brazil became the largest producer, and coffee was linked with plantation economies and slavery.

Today arabica accounts for the larger part of world coffee production, with Brazil, Colombia, Ethiopia and Central American countries major growers. Climate change, coffee leaf rust and low genetic diversity threaten the crop, while specialty coffee culture has focused on origin, processing and fair trade.

Roasted beans are ground and brewed as espresso, filter, French press, Turkish, Ethiopian jebena and many other styles, or processed into instant coffee and cold brew. Coffee is used to flavour desserts, liqueurs and savoury rubs. Green coffee extract is sold as a supplement.

In Ethiopia the coffee ceremony is an important social ritual, and spent grounds are used as garden compost or in scrubs. The cherry husks are dried as cascara for tea. Beans are also sold as chocolate-covered snacks, and ground coffee is used in desserts such as tiramisu and in meat rubs.

In large population studies, moderate coffee drinking, about three to four cups a day, is associated with lower risk of type 2 diabetes, Parkinson's disease and some liver conditions, and generally not with higher heart disease risk, but these are observational findings. Caffeine improves alertness and can disturb sleep and raise anxiety in sensitive people. Unfiltered coffee can raise LDL cholesterol modestly.