Coffee
 A cup of brewed coffee | |
| Type | Brewed beverage |
|---|---|
| Source | Roasted seeds of Coffea species |
| Main species | Coffea arabica, Coffea canephora (robusta) |
| Origin | Ethiopia; first cultivated in Yemen |
| Active compound | Caffeine |
Coffee is a beverage brewed from the roasted and ground seeds of Coffea shrubs. It is among the most widely traded agricultural commodities in the world, and one of the most consumed drinks after water and tea.
The plant
[edit]Coffea is a genus of flowering shrubs native to tropical Africa. Two species account for nearly all production:
- Coffea arabica — about 60% of world output. Grown at altitude, more aromatic and less bitter, more susceptible to disease and to warming.
- Coffea canephora (robusta) — hardier, higher-yielding, roughly twice the caffeine, and a harsher flavour. Used in instant coffee and in espresso blends for body and crema.
The fruit is a small drupe, the "cherry", usually containing two seeds. Coffee grows in the tropical belt between the Tropics of Cancer and Capricorn; Brazil has been the largest producer since the nineteenth century, followed by Vietnam, Colombia and Indonesia.
From cherry to cup
[edit]- Harvesting. Cherries ripen unevenly, so selective hand-picking gives better quality than stripping a branch at once.
- Processing. The washed method ferments off the fruit before drying, giving a cleaner, more acidic cup. The natural method dries the whole cherry, giving heavier, fruitier flavours.
- Roasting. Green beans are heated to between about 200 and 250 °C. Hundreds of aromatic compounds form through the Maillard reaction and caramelisation; almost everything recognisable as coffee flavour is created here rather than in the seed.
- Grinding and brewing. Hot water dissolves acids, sugars and caffeine. Under-extraction tastes sour and thin; over-extraction tastes bitter and hollow.
Caffeine
[edit]Caffeine is an alkaloid that acts as a natural insecticide in the plant. In humans it blocks adenosine receptors in the brain; adenosine accumulates during waking hours and promotes sleepiness, so blocking it masks the sensation of tiredness without reducing the underlying need for sleep. A cup of brewed coffee contains roughly 80–100 mg. Tolerance develops within days, and abrupt cessation commonly produces headache and irritability for a few days.
History
[edit]Coffee's origin is Ethiopian, where Coffea arabica grows wild; the story of the goatherd Kaldi noticing his goats' liveliness after eating the berries is a much later legend. Documented cultivation and roasting begin in fifteenth-century Yemen, in Sufi monasteries, where the drink was used to stay awake through night prayers. From the port of Mocha it spread through the Ottoman Empire.
Coffeehouses followed, and with them repeated official anxiety. Coffee was banned in Mecca in 1511 and in Cairo shortly after; a 1675 English proclamation attempted to suppress coffeehouses as places where "divers false, malitious and scandalous reports" were spread against the government. The ban was withdrawn within days.
The coffeehouse became an institution of European public life in the seventeenth and eighteenth centuries — cheap admission, mixed company, newspapers provided. Lloyd's of London began in a coffeehouse frequented by shipping merchants, and the London Stock Exchange traces its origins to Jonathan's. The drink was also inseparable from colonial plantation agriculture and slavery, particularly in the Caribbean and Brazil.
Economics
[edit]Coffee is grown mostly by smallholders in the tropics and consumed mostly in wealthier temperate countries. Most of the value is added after export — in roasting, branding and retail — so a small share of the retail price reaches the grower. Prices are set on volatile commodity exchanges, and certification schemes such as fair trade attempt to guarantee a floor. Rising temperatures are expected to reduce the land suitable for arabica substantially over the coming decades.