Espresso Perfetto

Caffè espresso or espresso (never pronounced “ex-presso”!) is a concentrated coffee beverage brewed by forcing steam or hot water under pressure through finely ground coffee. Perfetto is “perfect” in Italian. All baristas should aim to extract Perfect Espresso shots each and every time.

Espresso brewing, with a dark reddish-brown foam, called crema or schiuma.

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. With some espresso machines, espresso can now be 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 30 and 45 ml (1 to 1.5 fluid ounces) in size. Many of espresso’s chemical components quickly degrade by oxidation. 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.

A modern espresso machine

Espresso Brewing Process

Preparation of espresso requires an espresso machine. The act of producing a shot of espresso is termed “pulling” a shot. The term originates 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 of ground coffee for a single shot or 12 to 18 grams 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.

The Moka per il caffè is a three part stove-top unit with loosely packed grounds

Espresso Roast

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. A counter-trend to the “always dark” roasts of some major U.S. chains has accelerated in recent years. These roasters vary the roast level with the bean type, aiming to develop distinctive flavors from each.

Origins of the word: Espresso

The origin of the term “espresso” is the subject of considerable debate. Although some Anglo-American dictionaries simply refer to “pressed-out” (rooted in the Latin origin of the word), “espresso,” much like the English word “express,” conveys the sense of “just for you” and “quickly,” both of which can be related to the method of espresso preparation.

The words express, expres and espresso each have several meanings in English, French and Italian. The first meaning is to do with the idea of ‘expressing’ or squeezing the flavor from the coffee using the pressure of the steam. The second meaning is to do with speed, as in a train. Finally there is the notion of doing something ‘expressly’ for a person… The first Bezzera and Pavoni espresso machines in 1906 took forty-five seconds to make a cup of coffee, one at a time, expressly for you.

In Portugal espresso is called “bica” (in Lisbon) or “cimbalino” (in Porto), or just simply “café” (in full café expresso, Portuguese meaning coffee, which invariably means an espresso in all of Portugal, unless otherwise specifically stated).

Expresso is the form used in France, Spain (expreso), Portugal, and parts of Canada. It’s usage is discouraged in the English language.

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.

The terms “espresso crema” or “espresso crema effect” are sometimes used as analogue models for material scientific issues. E.g. surfaces of ancient ceramics can erode due to post-depositional processes resulting in a measurable chemical alteration and a physical increase of porosity which leads to an obvious surface brightening of an actual dark material.

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