Espresso is a concentrated beverage brewed by forcing a small amount of nearly boiling water under pressure through finely ground coffee beans. Espresso often has a thicker consistency than coffee brewed by other methods, a higher concentration of suspended and dissolved solids, and crema (meaning cream, but being a reference to the foam with a creamy texture that forms as a result of the pressure).
As a result of the pressurized brewing process the flavors and chemicals in a typical cup of coffee are very concentrated. Espresso is the base for other drinks, such as a latte, cappuccino, macchiato, mocha, or americano. Espresso has more caffeine per unit volume than most beverages, but the usual serving size is smaller—a typical 60 mL (2 US fluid ounce) of espresso has 80 to 150 mg of caffeine, little less than the 95 to 200 mg of a standard 240 mL (8 US fluid ounces) cup of drip-brewed coffee.
Espresso is made by forcing very hot water under high pressure through finely ground, compacted coffee. Tamping down the coffee promotes the water's even penetration of the grounds. This process produces an almost syrupy beverage by extracting both solid and dissolved components. It also produces the definitive crema, by emulsifying the oils in the ground coffee into a colloid, which does not occur in other brewing methods. There is no universal standard defining the process of extracting espresso, but there are several published definitions which attempt to place constraints on the amount and type of ground coffee used, the temperature and pressure of the water, and the rate of extraction. Generally, one uses an espresso machine to make espresso. The act of producing a shot of espresso is often termed "pulling" a shot, originating from lever espresso machines, which require pulling down a handle attached to a spring-loaded piston, forcing hot water through the coffee at high pressure. Today, however, it is more common for the pressure to be generated by an electric pump.
Angelo Moriondo’s Italian patent, which was registered in Turin in 1884 (No. 33/256), is notable. Ian Bersten, whose history of coffee brewers is cited below, claims to have been the first to discover Moriondo’s patent. Bersten describes the device as “… almost certainly the first Italian bar machine that controlled the supply of steam and water separately through the coffee” and Moriondo as “... certainly one of the earliest discoverers of the expresso machine, if not the earliest.” Unlike true espresso machines, it was a bulk brewer, and did not brew coffee “expressly” for the individual customer.
Seventeen years later, in 1901, Milanese Luigi Bezzera came up with a number of improvements to the espresso machine. He patented a number of these, the first of which was applied for on the 19th of December 1901. It was titled “Innovations in the machinery to prepare and immediately serve coffee beverage” (Patent No. 153/94, 61707, granted on the 5th of June 1902).
In 1905, the patent was bought by Desiderio Pavoni, who founded the “La Pavoni” company and began to produce the machine industrially (one a day) in a small workshop in Via Parini in Milan.
The popularity of espresso developed in various ways; a detailed discussion of the spread of espresso is given in (Morris 2007), which is a source of various statements below.
In Italy, the rise of espresso consumption was associated with urbanization, espresso bars providing a place for socialization. Further, coffee prices were controlled by local authorities, provided the coffee was consumed standing up, encouraging the "stand at a bar" culture.
Initially, expatriate Italian espresso bars were downmarket venues, serving the working class Italian diaspora – and thus providing appeal to the alternative subculture / counterculture; this can still be seen in the United States in Italian American neighborhoods, such as Boston's North End, New York's Little Italy, and San Francisco's North Beach. As specialty coffee developed in the 1980s (following earlier developments in the 1970s and even 1960s), an indigenous artisanal coffee culture developed, with espresso instead positioned as an upmarket drink.
The main variables in a shot of espresso are the "size" and "length". This terminology is standardized, but the precise sizes and proportions vary substantially.
Cafés generally have a standardized shot (size and length), such as "triple ristretto", only varying the number of shots in espresso-based drinks such as lattes, but not changing the extraction – changing between a double and a triple requires changing the filter basket size, while changing between ristretto, normale, and lungo require changing the grind, and cannot easily be accommodated in a busy café, as fine tweaking of the grind is a central aspect to consistent quality espresso-making, which is disrupted by major changes, such as ristretto to lungo.
The main variables in a shot of espresso are the "size" and "length". This terminology is standardized, but the precise sizes and proportions vary substantially.
Cafés generally have a standardized shot (size and length), such as "triple ristretto", only varying the number of shots in espresso-based drinks such as lattes, but not changing the extraction – changing between a double and a triple requires changing the filter basket size, while changing between ristretto, normale, and lungo require changing the grind, and cannot easily be accommodated in a busy café, as fine tweaking of the grind is a central aspect to consistent quality espresso-making, which is disrupted by major changes, such as ristretto to lungo.
The length of the shot can be ristretto (reduced), normale/standard (normal), or lungo (long): these correspond to a smaller or larger drink with the same amount of ground coffee and same level of extraction. Proportions vary, and the volume (and low density) of crema make volume-based comparisons difficult (precise measurement uses the mass of the drink), but proportions of 1:1, 1:2, and 1:3–4 are common for ristretto, normale, and lungo, corresponding to 1, 2, and 3–4 US fl oz (30 ml, 60 ml, 90–120 ml) for a double shot.
Ristretto is the most commonly used of these terms, and double or triple ristrettos are particularly associated with artisanal espresso.
Ristretto, normale, and lungo are not simply the same shot, stopped at different times – this will result in an underextracted shot (if run too short a time) or an overextracted shot (if run too long a time). Rather, the grind is adjusted (finer for ristretto, coarser for lungo) so the target volume is achieved by the time extraction finishes.
A significantly longer shot is the caffè crema, which is longer than a lungo, ranging in size from 4–8 US fl oz (120–240 ml), and brewed in the same way, with a coarser grind.
The method of adding hot water produces a milder version of original flavor, while passing more water through the load of ground coffee will add other flavors to the espresso, which might be unpleasant for some people.
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