Coffee

A cafe mocha (made from compressed espresso grounds, combined with steamed milk and chocolate sauce) with whipped cream on top and a glazed donut.

Coffee, brewed from beans, is a popular drink across the entire world. Coffee beans are harvested from cherries grown from the genus of plants known as Coffea. There are over 500 genera and 6,000 species of tropical coffea trees.

A coffee cherry's outer skin is the exocarp, beneath it a thin layer of pulp known as mesocarp, then a slimy layer called parenchyma. The beans within this are covered in a thin layer named the endocarp. Inside the endocarp are two beans, usually positioned next to each other, divided by a membrane called the spermoderm.

Although the availability of coffee is ubiquitous, coffea trees can only be grown in certain climates. The most effective places to grow coffee are in tropical or sub-tropical environments at high altitudes. Because of this, distinct places in the world are prime for coffea cultivation; Brazil, Columbia, India, Indonesia, Mexico, Puerto Rico, and Vietnam are the top coffea growing and exporting countries.

Coffee can be served in a number of ways. The most traditional western method is by which the roasted beans are ground, and then placed into a paper filter, where hot water is then strained into the filter, soaking the grounds, and then into a coffee pot. The appliances that produce coffee in this way are known as drip-style coffee makers, or "drip-pots".

Greek, Turkish and other coffees emanating from the Ottoman period are made by rapidly boiling roughly-ground roasted beans, along with the appropriate amount of sugar, in a special small metal pan. The resulting mix is poured into a small cup, of which only the upper liquid is drunk. The bottom third or so of the cup contains coffee grounds.

A popular, originally Italian, way of making coffee is to finely grind heavily roasted beans and compress them into a filter. Hot water is then compressed into the filter, producing a concentrated form of coffee that has a very dark color and high caffeine content. This is known simply as espresso, and is often served in quantites of ounces, or "shots". These espresso machines can create pressure by either heating water up to its boiling point, creating steam to produce the concentrate, or through a pump that injects water into the compressed grounds. The amount of compression (measured in pounds/square inch (psi)) varies between the different styles of appliances.