Coffee (thing)

The genus Coffea is a member of the Rubiaceae, family which includes more than 500 genera and 6,000 species of tropical trees and shrubs. Species of Coffea can range from small shrubs to tall trees, and the leaves can range in color from purple to yellow.There are some 25 major species of Coffea, but the beans that are used to make the drink mostly come from Coffea arabica and Coffea canephora (var. robusta). Arabica coffee accounts for about 70% of the world's coffee production.

A smidgen of history

Coffee was introduced to Europe in the 17th century. It came from Arabia, via Turkey. The Arabs are considered to have been the world's first coffee drinkers: in Arabic countries the drinking of coffee was already a daily ritual in the 15th century. When European explorers reached Arabia in the 15th and 16th century, they soon discovered the coffee houses, where a drink was served that was both invigorating and tasty. In 1615 the first ship carrying coffee sailed from Turkey to Europe. The first European coffee house was opened in 1645 in Venice.

Growing coffee

Coffee is grown in most countries around the equator, where there is a tropical or subtropical climate. Coffee trees need an even temperature (between 20 and 25 degrees C) and grow up to heights of 2000 metres. Generally, the higher the tree grows, the better the coffee. Coffee trees grow during the wet season, and rest during the dry season.

From coffee plant to ground coffee

Mature coffee trees bear fruit in clusters along the branches of the trees, typically once a year. The fruit, that is referred to as 'berry' or 'cherry' turns red when it is ready to be harvested, and contains two flat seeds. These are the coffee beans. Coffee is harvested by hand, by strip picking or selective picking. Strip picking means the entire crop is picked at one pass. This means that berries of different ripeness are all picked at the same time. Selective picking means that several passes are made among the coffee trees, in which only the fully ripe berries are taken. This takes more time and is thus more expensive, and is only used for arabica beans, which are considered the best beans.

After picking, the beans are processed. There are two methods of processing (preparing the bean for roasting). The dry method means that the cherries are spread out on a concrete, brick or matting surface to dry. They are raked at regular intervals to prevent fermentation. If rain falls or the temperature drops, the beans have to be covered for protection. When the cherries are dry enough, they are stored in silos where their moisture content drops even further.
In the wet method a pulping machine is used to separate the bean from the skin and pulp of the cherry. The skin and pulp are washed away with water and the lighter, immature beans are separated from the heavier mature beans. The beans are then stored in fermentation tanks to remove the slimy layer that still covers the beans. The beans are then dried and kept until export.
Both the beans processed with the dry method and those processed with the wet method are hulled after drying, to remove the dried outer coverings of the original cherries (dry method) or to remove the parchment layer left on the beans (wet method).

The green beans are graded, sorted and exported. Then comes the roasting, a heat treatment which transforms the green beans into aromatic brown nuggets that are sold whole or ground. At an air temperature of about 180 degrees Celsius (550 degrees Fahrenheit), the sugars in the beans caramelize and the beans slowly turn dark brown. This process, that is called pyrolysis is the most important part of the processing of the beans, as this is the moment that determines the final taste and quality of the coffee. The darker the beans are roasted, the stonger the taste of the coffee. When the beans are done, they are cooled abruptly with air and water to stop the pyrolysis process. The roasting of the beans is performed in the consumer countries rather than the production countries (and preferrably as close in time as possible to consumption), because roasted beans lose their flavour rather quickly.

Decaffeinated coffee

Some people prefer their coffee without the staying awake effects of caffeine. For these people there is decaffeinated coffee. Decaffeinating coffee is done by removing the caffeine from the coffee beans before roasting. This can be accomplshed in several ways. One way is by soaking the green beans in water. The caffeine dissolves in the water and is then pumped through a bed of active carbon. Afterwards the beans are dried, cooled, and roasted in the usual way.
Another way of decafeinating is by using DCM (dichloremethane). The beans are soaked in this extraction medium and the caffeine dissolves in it. The beans are then steamed to remove the DCM, dried and roasted. After decaffeinating, the caffeine content of the beans has dropped from 1 - 2.5% to 0.1%.

Preparing coffee

There are many different ways of making the drink called coffee, but they all involve grinding the roasted coffee beans and then bringing the ground coffee into contact with hot water. The most basic way of making coffee is boiling water with ground coffee, then pouring into cups... but this way means there will be lots of ground stuff in your drink.
More sophisticated methods use filters to separate the dregs from the drink. The most complicated way must be with the espresso machine, that with a pressure of 9 bar forces the water through finely gound coffee, the most entertaining way the glass percolator...