Т е к с т 7. Coffee

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Coffee is a widely consumed beverage prepared from roasted seeds, commonly called beans, of the coffee plant. Coffee was first consumed in the 9th century, when it was discovered in the highlands of Ethiopia. From there, it spread to Egypt and Yemen, and by the 15th century had reached Persia, Turkey, and northern Africa. From the Muslim world, coffee spread to Italy, then to the rest of Europe and the Americas. Today, coffee is one of the most popular beverages worldwide.

Processing

Roasting. Coffee berries and their seeds undergo multi-step processing before they become the roasted coffee, known to most of Western consumers. First, coffee berries are picked, generally by hand. Then, the flesh of the berry is removed, usually by machine, and the seeds – usually called beans – are fermented to remove the slimy layer of mucilage, still present on the bean. When the fermentation is finished, the beans are washed with large quantities of fresh water to remove the fermentation residue. Finally, the seeds are dried, sorted and labeled as green coffee beans.

The next step in the process is the roasting of the green coffee. Coffee is usually sold in a roasted state, and all coffee is roasted before it is consumed. The roasting process influences the taste of the beverage by changing the coffee bean both, physically and chemically. The bean decreases in weight as moisture is lost, but increases in volume, causing it to become less dense. The density of the bean also influences the strength of the coffee and requirements for packaging.

The actual roasting begins when the temperature inside the bean reaches 200°C, though different varieties of beans differ in moisture and density and therefore roast at different rates. During roasting, caramelization occurs as intense heat breaks down starches in the bean, changing them to simple sugars that begin to brown, changing the color of the bean. Sucrose is rapidly lost during the roasting process and may disappear entirely in darker roasts. During roasting, aromatic oils, acids, and caffeine weaken, changing the flavor; at 205°C, other oils start to develop. One of these oils is caffeol, created at about 200°C, which is largely responsible for coffee's aroma and flavor.

Depending on the color of the roasted beans, they will be labeled as light, cinnamon, medium, high, city, full city, French, or Italian roast. Darker roasts are generally smoother, because they have less fiber content and a more sugary flavor. Lighter roasts have more caffeine, resulting in a slight bitterness, and a stronger flavor from aromatic oils and acids destroyed by longer roasting times. A small amount of chaff is produced during roasting from the skin left on the bean after processing. Chaff is usually removed from the beans by air movement, though a small amount is added to dark roast coffees to soak up oils on the beans.

Decaffeination may also be part of the processing that coffee seeds undergo. Seeds are decaffeinated when they are still green. Many methods can remove caffeine from coffee, but all involve either soaking beans in hot water or steaming them, then using a solvent to dissolve caffeine-containing oils. Decaffeination is often done by processing companies, and the extracted caffeine is usually sold to the pharmaceutical industry.

Preparation. Coffee beans must be ground and brewed in order to create a beverage. Grinding the roasted coffee beans is done at a roastery, in a grocery store, or in the home. They are most commonly ground at a roastery then packaged and sold to the consumer, though "whole bean" coffee can be ground at home. Coffee beans may be ground in several ways. A coffee mill uses revolving elements to crush or tear the bean, an electric grinder chops the beans with blades moving at high speeds, and a mortar and pestle grinds the beans to a powder.

The type of grind is often named after the brewing method for which it is generally used. Turkish grind is the finest grind, while coffee percolator or French press are the coarsest grind. The most common grinds are between the extremes; a medium grind is used in most common home coffee brewing machines. Coffee may be brewed by several methods: boiling, gravity, steeping, or pressure. Brewing coffee by boiling was the earliest method, and Turkish coffee is an example of this method. It is prepared by powdering the beans with a mortar and pestle, then adding the powder to water and bringing it to a boil in a pot called a cezve. This produces a strong coffee with a layer of foam on the surface.

Machines such as percolators or automatic coffeemakers brew coffee by gravity. In an automatic coffeemaker, hot water drips onto coffee grounds held in a coffee filter made of paper or perforated metal, allowing the water to seep through the ground coffee while absorbing its oils and essences. Gravity causes the liquid to pass into a pot while the used coffee grounds are retained in the filter. In a percolator, boiling water is forced into a chamber above a filter by pressure created by boiling. The water then passes downwards through the grounds due to gravity, repeating the process until shut off by an internal timer.

Coffee may also be brewed by steeping in a device such as a French press (also known as a cafetière). Ground coffee and hot water are combined in a coffee press and left to brew for a few minutes. A plunger is then depressed to separate the coffee grounds, which remain at the bottom of the container. Because the coffee grounds are in direct contact with the water, all the coffee oils remain in the beverage, making it stronger and leaving more sediment than in coffee made by an automatic coffee machine.

The espresso method forces hot, but not boiling, pressurized water through ground coffee. This results in a stronger flavor and more chemical changes, such as a higher caffeine content. It also results in more particles in the liquid than in coffee made by an automatic coffee machine, and the resulting beverage has a thicker consistency. It has a reddish-brown foam called crema that floats on the surface.

Health and Pharmacology

Coffee appears to reduce the risk of Alzheimer's disease, Parkinson's disease, heart disease, diabetes mellitus type 2, cirrhosis of the liver, and gout. Some health effects are due to the caffeine content of coffee, as the benefits are only observed in those who drink caffeinated coffee, while others appear to be due to other components. For example, the antioxidants in coffee prevent free radicals from causing cell damage.

Coffee's negative health effects are mostly due to its caffeine content. Research suggests that drinking caffeinated coffee can cause a temporary increase in the stiffening of arterial walls. Excess coffee consumption may lead to a magnesium deficiency or hypomagnesaemia. Some studies suggest that it may have a mixed effect on short-term memory, by improving it when the information to be recalled is related to the current train of thought, but making it more difficult to recall unrelated information. Nevertheless, most of medical experts guess, that drinking three cups of coffee per day does not have significant health risks for adults.