The two most common sources of coffee beans are the highly regarded Coffea arabica, and the “robusta” form of the hardier Coffea canephora. The latter is resistant to the coffee leaf rust (Hemileia vastatrix), but has a more bitter taste. Coffee plants are cultivated in more than 70 countries, primarily in equatorial Latin America, Southeast Asia, and Africa. Once ripe, coffee “berries” are picked, processed, and dried to yield the seeds inside. The seeds are then roasted to varying degrees, depending on the desired flavor, before being ground and brewed to create coffee.
Coffee is slightly acidic (pH 5.0–5.1) and can have a stimulating effect on humans because of its caffeine content. It is one of the most popular drinks in the world. It can be prepared and presented in a variety of ways. The effect of coffee on human health has been a subject of many studies; however, results have varied in terms of coffee’s relative benefit. The majority of recent research suggests that moderate coffee consumption is benign or mildly beneficial in healthy adults. However, coffee can worsen the symptoms of conditions such as anxiety, largely due to the caffeine and diterpenes it contains.
Coffee cultivation first took place in southern Arabia; the earliest credible evidence of coffee-drinking appears in the middle of the 15th century in the Sufi shrines of Yemen. In East Africa and Yemen, coffee was used in native religious ceremonies. As these ceremonies conflicted with the beliefs of the Christian church, the Ethiopian Church banned the secular consumption of coffee until the reign of Emperor Menelik II.
An important export commodity, coffee was the top agricultural export for twelve countries in 2004, and it was the world’s seventh-largest legal agricultural export by value in 2005. Green (unroasted) coffee is one of the most traded agricultural commodities in the world. Some controversy is associated with coffee cultivation and its impact on the environment. Consequently, organic coffee is an expanding market.