Coffee preparation

Coffee preparation is the process of turning coffee beans into a beverage. While the particular steps needed vary with the type of coffee desired and with the raw material being utilized, the process is composed of four basic steps; raw coffee beans must be roasted, the roasted coffee beans must then be ground, the ground coffee must then be mixed with hot water for a certain time (brewed), and finally the liquid coffee must be separated from the now used and unwanted grounds.

Coffee is always brewed by the user immediately before drinking. In most areas, coffee may be purchased unprocessed, or already roasted, or already roasted and ground. Coffee is often vacuum packed to prevent oxidation and lengthen its shelf life.

Brewing

Coffee can be brewed in several different ways, but these methods fall into four main groups depending upon how the water is introduced to the coffee grounds.
Brewed coffee kept hot will deteriorate rapidly in flavor. Even at room temperature, deterioration will occur; however, if kept in an oxygen-free environment it can last almost indefinitely at room temperature.

Electronic coffee makers boil the water and brew the infusion with little human assistance and sometimes according to a timer. Some grind beans automatically before brewing.

Boiling

Despite the name, care should be taken not to actually boil coffee for more than an instant because it becomes bitter.
  • The simplest method is to put the ground coffee in a cup, pour in hot water and let it cool while the grounds sink to the bottom. This is a traditional method for making a cup of coffee that is still used in parts of Indonesia. This method (known as "mud coffee" in the Middle East owing to an extremely fine grind that results in a mud-like sludge at the bottom of the cup) allows for extremely simple preparation, but the drinker must be careful if they want to avoid drinking grounds either from this layer or floating at the surface of the coffee (which can be avoided by dribbling cold water onto the 'floaters' from the back of a spoon). If the coffee beans are not ground finely enough, the grounds do not sink.
  • "Cowboy coffee" is made by heating coarse grounds with water in a pot, letting the grounds settle and pouring off the liquid to drink, sometimes filtering it to remove fine grounds. While the name suggests that this method was used by cowboys, presumably on the trail around a campfire, it is used by others; some people prefer this method. This method is still used in certain situations in Finland, Norway and Sweden, which have the highest consumption of coffee per-capita, but filter brewing is the standard method there today.

The above methods are sometimes used with hot milk instead of water.

Turkish coffee also known as Greek coffee, Arabic coffee, etc., a very early method of making coffee, is used in the Middle East, North Africa, East Africa, Turkey, Greece, Balkans and Russia. Very finely ground coffee, optionally sugar, and water are placed in a narrow-topped pot, called an cezve (Turkish), kanaka (Egyptian), briki (Greek), džezva (Štokavian) or turka (Russian) and brought to the boil then immediately removed from the heat. It may be very briefly brought to the boil two or three times. Turkish coffee is often flavored with cardamom, particularly in Arab countries. The resulting strong coffee, with foam on the top and a thick layer of grounds at the bottom, is drunk from small cups. The pot is often referred to as an ibrik in the West, in the mistaken belief that it is the Turkish language name for the pot

Steeping

A cafetière (or French press) is a tall, narrow cylinder with a plunger that includes a metal or nylon mesh filter. Coffee is placed in the cylinder and boiling water is poured in. The coffee and hot water are left in the cylinder for a few minutes (typically 4–7 minutes) and the plunger is pushed down, leaving the filter immediately above the grounds, allowing the coffee to be poured out while the filter retains the grounds. Depending on the type of filter, it is important to pay attention to the grind of the coffee beans, though a rather coarse grind is almost always called for. A plain glass cylinder may be used, or a vacuum flask arrangement to keep the coffee hot (not to be confused with a vacuum brewer; see below).

Coffee bags are less often used than tea bags. They are simply disposable bags containing coffee; the grounds do not mix with the water so no extra filtering is required.

A vacuum brewer consists of two chambers: a pot below, atop which is set a bowl or funnel with its siphon descending nearly to the bottom of the pot. The bottom of the bowl is blocked by a filter of glass, cloth or plastic, and the bowl and pot are joined by a gasket that forms a tight seal. Water is placed in the pot, the coffee grounds are placed in the bowl, and the whole apparatus is set over a burner. As the water heats, it is forced by the increasing vapor pressure up the siphon and into the bowl where it mixes with the grounds. When all the water possible has been forced into the bowl the brewer is removed from the heat. As the water vapor in the pot cools, it contracts, forming a partial vacuum and drawing the coffee down through the filter.

The AeroPress is a device invented in 2005 that combines steeping and pressure. Hot water is poured onto ground coffee, similarly to a French press, but soon after the coffee is forced through a paper microfilter using pressure. This filter allows a finer grind and removes more of the sediment than the stainless steel mesh filter of a French press.

Gravity

Drip brew (also known as filter or American coffee) is made by letting hot water drip onto coffee grounds held in a coffee filter surrounded by a filter holder or brew basket. Drip brew makers can be simple filter holder types manually filled with hot water, or they can use automated systems as found in the popular electric drip coffeemaker. Strength varies according to the ratio of water to coffee and the fineness of the grind, but is typically weaker than espresso, though the final product contains more caffeine. By convention, regular coffee brewed by this method is served in a brown or black pot (or a pot with a brown or black handle), while decaffeinated coffee is served in an orange pot (or a pot with an orange handle).

A variation is the traditional Neapolitan flip coffee pot, or Napoletana, a drip brew coffee maker for the stovetop. It consists of a bottom section filled with water, a middle filter section, and an upside-down pot placed on the top. When the water boils, the coffee maker is flipped over to let the water filter through the coffee grounds.

The common electric percolator — which was in almost universal use in the United States prior to the 1970s, and is still popular in some households today — differs from the pressure percolator described above. It uses the pressure of the boiling water to force it to a chamber above the grounds, but relies on gravity to pass the water down through the grounds, where it then repeats the process until shut off by an internal timer. The coffee produced is held in low esteem by some coffee aficionados because of this multiple-pass process. Many coffee drinkers still prefer gravity percolation because they claim it delivers a richer cup of coffee in comparison to drip brewing.

It may be interesting to note that the amount of coffee used affects both the strength and the flavor of the brew in a typical filter coffee maker. The softer flavors come out of the coffee first and the more bitter flavors only after some time, so a large brew will tend to be both stronger and bitterer. This can be modified by stopping the filtration after a planned time and then adding hot water to the brew instead of waiting for all the water to pass through the grounds.

Pressure

Espresso is made with hot water at between 91 °C (195 °F) and 96 °C (204 °F) forced, under a pressure of between eight and nine atmospheres (800–900 kPa), through a lightly packed matrix (called a puck) of finely ground coffee. It can be served alone (often after an evening meal), and is the basis for many coffee drinks. It is one of the strongest tasting forms of coffee regularly consumed, with a distinctive flavor and crema, a layer of emulsified oils in the form of colloidal foam standing over the liquid.

A moka pot, also known as "Italian coffeepot"or "caffettiera", is a three-chamber design which boils water in the lower section and forces the boiling water through coffee grounds held in the middle section, separated by a filter mesh from the top section. The resultant coffee (almost espresso strength, but without the crema) is collected in the upper section. These pots usually sit directly on a heater or stove. Some models have a transparent glass or plastic top.

Various types of single-serving coffee machines force hot water under pressure through a coffee pod composed of finely ground coffee sandwiched between two layers of filter paper or a proprietary capsule containing ground coffee.