Introduction to Coffee
Coffee, a hot drink made from the roasted beans (seeds) of the coffee tree. Coffee is a popular beverage in North America, commonly consumed at breakfast or during the morning "coffee break" at work. It contains 1 to 2 per cent caffeine, a substance that stimulates the central nervous system. Caffeine increases wakefulness and alertness, but excessive amounts can cause a number of unpleasant symptoms. Persons who regularly drink more than five cups of coffee daily may experience withdrawal symptoms if they stop drinking it.
The Coffee Tree and Bean
The coffee tree or shrub is a member of the madder family. It will grow to be 10 to 15 feet (3 to 4.5 m) high, but is often kept pruned to a height of 6 or 7 feet (about 2 m) so that the berries, or cherries, may be gathered easily. The leaves are dark green and the flowers are white. When ripe, the coffee berry is blackish red with yellow pulp. It contains two seeds, or beans, that are flat on one side and rounded on the other. The flat surfaces face each other.
Coffee trees grow best in tropical regions, at altitudes of 2,000 to 6,000 feet (600 to 1,800 m) above sea level. Seeds are planted in nurseries or directly in the groves where the trees will grow.
Coffee trees are susceptible to a fungus disease called coffee rust. Coffee rust attacks the leaves and weakens the plants to such an extent that they cannot produce berries. The disease can generally be controlled by planting resistant varieties and spraying with fungicides, but outbreaks have occasionally severely curtailed the coffee harvest.
Coffee trees begin to bear fruit when they are three to five years old. They live 20 to 30 years. Some countries have two coffee crops each year. Each tree yields approximately five pounds (2.3 kg) of berries. These berries produce about one pound (450 g) of green coffee, or slightly less than a pound of roasted coffee.
There are several varieties of coffee trees, with beans of varying sizes and colors. The most widely grown is Arabica. The many commercial classifications of coffee are named for the areas in which they are grown or the ports from which they are shipped. Included are Medellin, Armenia, and Manizales, from Colombia; Coatopecs, from Mexico; and Salvadors, from El Salvador. Mocha is a variety grown in southern Arabia. Java is grown on the island of Java. Rio and Santos are Brazilian varieties. Retail brands are usually blends, roasted to produce the aromas and flavors popular with consumers.
Harvesting and Processing
The berries can be shaken from the tree if they all ripen at the same time; otherwise they must be picked by hand. The first step in processing the coffee beans is to separate them from the pulp and to remove the paperlike outer skin and silvery inner skin that surround each bean. In one common method, the pulp is separated by machine and the beans are allowed to ferment slightly. The beans are then washed and dried, and the two skin layers are removed by milling. The raw coffee beans are packed in bags and shipped to market.
The next step is to roast the green coffee beans. Roasting darkens the beans and develops their flavor and aroma. The amount of roasting affects the beans' final flavor. Roasting is usually done in the region where the beans will be sold and is controlled to suit the general tastes of the region.
The final step is to grind the beans. This step may be done at the roasting plant, at the store at the time of purchase, or in the home just before brewing. The fineness of the grind depends on the brewing method to be used.
Brewing Coffee
Coffee is brewed by exposing ground coffee to hot water. The hot water dissolves from the ground coffee the substances that give coffee its characteristic flavor, aroma, and color. The matter that remains—the grounds—is usually discarded.
Coffee can be brewed simply by boiling or steeping ground coffee in water. However, when made in this way, coffee tends to be stronger and more bitter than when the brewed coffee is kept separate from the grounds. In the United States, coffee is commonly brewed by the drip method. Typically, the ground beans are placed in a paper filter fitted into a receptacle with a hole at the bottom. Boiling water is poured onto the ground beans and coffee drips into a container below. In percolating, another common method, the ground coffee is put in a perforated basket at the top of a container in which water is heated. As the water boils, it bubbles upward through a hollow tube and then trickles back down through the ground coffee. As the process continues, the coffee in the container gradually becomes stronger.
A very thick, sweet coffee, called Turkish coffee, is made by bringing to a boil a mixture of water, sugar, and very finely ground coffee beans. Espresso is a strong coffee made by exposing ground, highly roasted coffee to steam. Cappuccino is an espresso coffee to which frothy cream or frothy milk has been added. Coffee is sometimes flavored with chicory, cinnamon, vanilla, chocolate, almond, or other additives.
Special Types of Coffee
Decaffeinated coffee (coffee with most of the caffeine removed) is usually produced by first softening green coffee beans with high-pressure steam and then extracting the caffeine with any of various solvents. Coffee that is decaffeinated using water or other naturally occurring solvents is called naturally decaffeinated coffee. Other decaffeinated coffee is produced with synthetic solvents, such as methylene chloride.
Instant, or soluble, coffee is prepared by first brewing the coffee in very large quantities at a processing plant. Water is then removed from the coffee by evaporation or by freeze-drying. Instant coffee is sold as a fine powder or, in the case of freeze-dried coffee, as granules. The user simply adds hot water.
A cereal substitute for coffee is made by blending roasted whole wheat with bran and molasses. Coffee substitutes were used extensively during the two World Wars when real coffee was unavailable.
History and Production
The coffee tree is believed to be native to Ethiopia. It was first cultivated in Arabia, possibly before the 10th century. The beverage first became popular in the Muslim world. It was introduced into western Europe from Turkey in the early 17th century. In the late 17th century, the French planted coffee trees in their Caribbean colonies and the Dutch planted them in Java. Coffee trees were taken from French Guiana to Brazil in 1727. The beverage, which was introduced to North America by the Dutch around 1670, became popular in the United States in the 1860's. Today, Brazil produces about one-third of the world's coffee, and about half of the world's production is consumed in the United States.
Only three of the many species of the genus Coffea are commercially important. These are C. arabica, C. liberica, and C. canephora (also known as C. robusta). Coffee is of the family Rubiaceae.