Espresso or caffè espresso (often mispronounced as: expresso ) is a concentrated coffee beverage brewed by forcing very hot water under high pressure through coffee that has been ground to a consistency between extremely fine and powder.
Espresso was developed in Milan, Italy in the early 20th century, but up until the mid-1940s it was a beverage produced solely with steam pressure. The invention of the spring piston lever machine and its subsequent commercial success changed espresso into the beverage as it is known today. Espresso is now produced with 0.82–1.8 MPa (8.2–18 atm; 120–265 PSI) of pressure.
The defining characteristics of espresso include a thicker consistency than drip coffee, a higher amount of dissolved solids than drip coffee per relative volume, and a serving size that is usually measured in shots, which are between 25 and 30 ml (around 1 fluid ounce) in size. Espresso is chemically complex and volatile, with many of its chemical components quickly degrading from oxidation or loss of temperature. The most distinguishing characteristic is "crema," a reddish-brown foam that floats on the surface and is composed of vegetable oils, proteins and sugars. Crema has elements of both emulsion and foam colloid.
As a result of the high-pressure brewing process, all of the flavors and chemicals in a typical cup of coffee are concentrated. For this reason, espresso lends itself to becoming the base for other drinks, such as lattes, cappuccino, macchiato and mochas.
While there can be significant variation, on a per-volume basis, espresso contains approximately three times the caffeine content of regular brewed coffee (1.700 g/l (50 mg per fluid ounce) of espresso versus 0.50–0.75 g/l (14–22 mg per ounce) for brewed coffee). Compared on the basis of usual serving sizes, a 30 ml (1 fluid ounce) shot of espresso has about half the caffeine of a standard 180 ml (6 fluid ounce) cup of American-style coffee, which varies from 80 to 130 mg.
Preparation of espresso requires an espresso machine. The act of producing a shot of espresso is termed "pulling" a shot. The term derives from lever espresso machines, which require pulling down a handle attached to a spring-loaded piston, forcing hot water through the coffee at the requisite pressure. To pull a shot of espresso, a metal filter-basket is filled with 7 to 10 grams (¼ to ⅓ ounce) of ground coffee for a single shot or 12 to 18 grams (⅜ to ⅝ ounces) for a double shot. The ground coffee is then tamped, using about 180 N (30–40 pounds) of force, evenly and rotationally applied, into a firm puck of coffee. The portafilter (or group handle) holds the filter-basket and is locked under the grouphead's diffusion block. When the brew process begins, pressurized water at 85–95 °C (185–203 °F) and approximately 900 kPa (130 psi; 9 bar) is forced into the grouphead and through the ground coffee in the portafilter. Water cooler than the ideal zone causes sourness; hotter than the ideal zone causes bitterness. High-quality espresso machines control the temperature of the brew water within a few degrees of the ideal. The serving temperature of espresso is significantly lower, typically around 60 to 70 °C (140 to 160 °F), owing to the small serving size and the cooling effects of the cup and of the pouring process.
This process produces a rich, almost syrupy beverage by extracting and emulsifying the oils in the ground coffee. An ideal shot of espresso should take between 20 and 30 seconds to arrive on a professional-grade machine, timed from when the coffee begins to flow from the machine (unless the machine has a "preinfusion" stage, which may add about 7 seconds to the process). Varying the fineness of the grind, the amount of pressure used to tamp the grinds, or the pump pressure itself can be used to bring the extraction time into this ideal zone. Most prefer to pull espresso shots directly into a pre-heated demitasse or shot glass, to maintain the ideal temperature of the espresso and preserve all of its crema. Apart from the espresso made manually by a barista, espresso is also made by automatic machines in which the brewing process takes place with an espresso-brewer.
Freshly brewed espresso must be served or mixed into other coffee beverages immediately, or it will begin to degrade due to cooling and oxidation. Temperature and time of consumption are important variables that must be observed to enjoy an ideal espresso; it should be consumed within 2 minutes from when it is served.
A common misconception about espresso is that it is a specific bean or roast level. Any bean or roasting level can be used to produce authentic espresso. While some major North American chains claim dark roasts as their espresso roasts, some of the winning blends used in the World Barista Championship have been what is classified as a medium, "City,” or "Full City" roast, with little or no visible surface oil on the beans.
The popularity of different levels of roast in espresso varies greatly. Espresso is typically made from a blend of beans roasted anywhere from very light to very dark. In Southern Italy, a darker roast is preferred, but in Northern Italy a medium roast is the more popular type . Companies such as Starbucks and Peet's have popularized darker roasts in North America and around the world, but the current trend in espresso coffee is matching the roast level to the bean type; this means that the most popular roast style is moving away from being associated with roast color, and more associated with what will produce the best flavor extraction in the cup for each region and type of bean.
In North America and other parts of the world, the title of barista has long been in use, especially in Italian-style cafes and coffeehouses, but the use of the term gained mainstream popularity when Starbucks started to call their counter staff by this title . Since the late 1990s, the term barista became synonymous with the person in a cafe who specialized in preparing espresso-based beverages for customers. Along with this came the term "home barista" to distinguish the home espresso enthusiast.
There is a current movement both outside of Europe and in parts of the continent to build pride and professionalism among baristas, encouraging them to consider their work as a serious craft, worthy of the respect granted to other food preparation artisans. In some ways this trend is meant to follow the traditions in places like Italy and France where the barista is considered a respectable career decision. In other ways, this trend is part of what is seen as the "Third Wave" in coffee, where transparency in information sharing is paramount, and the open discussion of ideas, concepts, opinions, and education are shared, even amongst competing businesses in the world of coffee and espresso. The trend is part of the bigger process in specialty coffee to promote coffee as a culinary drink, not as something "regular" or average.
In the United States, the Barista Guild of America was founded to promote the professionalism of baristas. Along with the Barista Guild, the Barista Championships also promote professionalism amongst baristas. The Barista Championships start as a series of regional events in numerous countries, including the United States, Canada, Australia, New Zealand, Italy, Great Britain, Norway, and Sweden, among others. The competition culminates in the annual World Barista Championship.
Responding to high turnover among coffee shop staff and a desire to reduce training costs, most commercial manufacturers are developing or improving lines of fully automatic machines, which allow a minimally-trained employee to create an espresso drink by merely pushing a button. Starbucks has been a notable adopter of these machines.
Espresso is the main type of coffee in most of southern Europe, notably Italy, France, Portugal, and Spain. It is also popular throughout much of the rest of Europe and in Argentina, Brazil, and Cuba, and urban centers in North America, Australia, and New Zealand. In Australia and New Zealand, espresso accounts for nearly all of the commercial cafe, coffeehouse and restaurant coffee business.
In the United States, South Florida’s influx of Cuban refugees brought their love of espresso with them although espresso consumption was limited largely to the Cuban community. With the rise of coffee chains such as Starbucks, Seattle's Best Coffee, Dunn Bros Coffee, Caribou Coffee, and others, espresso-based drinks rose in popularity in the 1990s in the United States, with the city of Seattle being generally viewed as the fount of the modern interest. In addition to the Italian style of coffee, these chains typically offer variations and innovations by adding syrups, whipped cream, flavour extracts, soy milk, and different spices to their drinks. Cities like San Francisco, New York, Philadelphia, Seattle, and Chicago have long traditions of espresso drinking, with the North Beach area in San Francisco being perhaps the most well known.
Espresso have become increasingly popular in recent years, in regions where "American Coffee" has been the main coffee for centuries. In northern Europe (Iceland, Finland, Sweden, Norway and Denmark), specialty coffee chains have emerged, selling various sorts of espresso from street corners and high streets. Europeans have embraced espresso as one of their favorite drinks. Many companies now have espresso machines, to be used free of charge by their employees.
Home espresso machines have increased in popularity with the general rise of interest in espresso, and with the Internet and its use as a tool to spread information about this beverage around the world. Today, a wide range of high-quality home espresso equipment can be found in specialist kitchen and appliance stores, online vendors, and department stores. The Internet has facilitated the spread of information about a wide range of espresso-based drinks, and can dispel (or promote) many myths on how to properly brew espresso.
In an Italian coffee bar, as in much of Europe, ordering "a coffee" (un caffè in Italian), means ordering an espresso. In France, the term café is normally used as well, but the French café is usually dark roasted.