Coffee
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Coffee, common name for any of a genus of trees of the madder family, and also for their seeds (beans) and for the beverage brewed from them. Of the 30 or more species of the genus, only three are important: Arabian, robusta, and Liberian. The shrub or small tree, 4.6 to 6 m (15 to 20 ft) high at maturity, bears shiny green, ovate leaves that persist for three to five years and white, fragrant flowers that bloom for only a few days. During the six or seven months after appearance of the flower, the fruit develops, changing from light green to red and, ultimately, when fully ripe and ready for picking, to deep crimson. The mature fruit, which resembles a cherry, grows in clusters attached to the limb by very short stems, and it usually contains two seeds, or beans, surrounded by a sweet pulp.
CHARACTERISTICS
Coffee contains a complex mixture of chemical components of the bean, some of which are not affected by roasting. Other compounds, particularly those related to the aroma, are produced by partial destruction of the green bean during roasting. Chemicals extracted by hot water are classified as nonvolatile taste components and volatile aroma components. Important nonvolatiles are caffeine, trigonelline, chlorogenic acid, phenolic acids, amino acids, carbohydrates, and minerals. Important volatiles are organic acids, aldehydes, ketones, esters, amines, and mercaptans. The principal physiological effects of coffee are due to caffeine, an alkaloid that acts as a mild stimulant. In recent years controversy arose over the possibly harmful effects of coffee beyond those recognized for people who should take few or no stimulants, and the dangers of caffeine for the fetuses of pregnant women. These debated studies were not substantiated, however.
A. Soluble Coffee
Soluble or instant coffee is an important production of the United States coffee industry. In its manufacture an extract is prepared by mixing coarsely ground and roasted coffee with hot water. The water is evaporated from the extract by various methods, including the use of spray driers or high-vacuum equipment. In freeze-dried coffee the coffee extract is frozen, and the water is removed by sublimation. The product is packed in vacuumized, sealed jars or in cans.
B. Decaffeinated Coffee
Caffeine can be removed from coffee by treating the green beans with chlorinated hydrocarbon solvents. The beans are roasted by ordinary procedures after removal of the solvents. Decaffeinated coffee is used by people hypersensitive to the caffeine present in regular coffee. In the 1980s nonchemical methods of decaffeination became more common.
Coffee, common name for any of a genus of trees of the madder family, and also for their seeds (beans) and for the beverage brewed from them. Of the 30 or more species of the genus, only three are important: Arabian, robusta, and Liberian. The shrub or small tree, 4.6 to 6 m (15 to 20 ft) high at maturity, bears shiny green, ovate leaves that persist for three to five years and white, fragrant flowers that bloom for only a few days. During the six or seven months after appearance of the flower, the fruit develops, changing from light green to red and, ultimately, when fully ripe and ready for picking, to deep crimson. The mature fruit, which resembles a cherry, grows in clusters attached to the limb by very short stems, and it usually contains two seeds, or beans, surrounded by a sweet pulp.CHARACTERISTICS
Coffee contains a complex mixture of chemical components of the bean, some of which are not affected by roasting. Other compounds, particularly those related to the aroma, are produced by partial destruction of the green bean during roasting. Chemicals extracted by hot water are classified as nonvolatile taste components and volatile aroma components. Important nonvolatiles are caffeine, trigonelline, chlorogenic acid, phenolic acids, amino acids, carbohydrates, and minerals. Important volatiles are organic acids, aldehydes, ketones, esters, amines, and mercaptans. The principal physiological effects of coffee are due to caffeine, an alkaloid that acts as a mild stimulant. In recent years controversy arose over the possibly harmful effects of coffee beyond those recognized for people who should take few or no stimulants, and the dangers of caffeine for the fetuses of pregnant women. These debated studies were not substantiated, however.
A. Soluble Coffee
Soluble or instant coffee is an important production of the United States coffee industry. In its manufacture an extract is prepared by mixing coarsely ground and roasted coffee with hot water. The water is evaporated from the extract by various methods, including the use of spray driers or high-vacuum equipment. In freeze-dried coffee the coffee extract is frozen, and the water is removed by sublimation. The product is packed in vacuumized, sealed jars or in cans.
B. Decaffeinated Coffee
Caffeine can be removed from coffee by treating the green beans with chlorinated hydrocarbon solvents. The beans are roasted by ordinary procedures after removal of the solvents. Decaffeinated coffee is used by people hypersensitive to the caffeine present in regular coffee. In the 1980s nonchemical methods of decaffeination became more common.
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