Espresso machines (espresso coffee makers) are designed to force water through tamped coffee grounds at a high pressure (e.g., 135 pounds per square inch) and high temperature (88-92º Celsius; 190-197º Fahrenheit) to extract the coffee's best flavors into a concentrated shot of espresso.
The Four Basic Types of Espresso Machines
Espresso machines come in four basic types:
Pump driven espresso machines are the most prevalent, used in the best espresso machines made by brands like Saeco, Delonghi, Gaggia and Faema.
Various models of these espresso makers are either commercial, prosumer espresso, or home espresso machines. Increasingly popular are pod espresso machines as well as the do-it-all super automatic espresso machines.
Pump-Driven Espresso Machines
The pump-driven espresso machine is the most popular type of espresso maker today, and uses a motor to create the necessary pressure required to force the water through the roasted, ground coffee to brew the espresso. Thus no manual force is required with a pump-driven espresso coffee maker.
In a pump-driven espresso machine, the water may be contained within a reservoir in the machine (this is usually the case with the lower cost home models), or may come directly from the on-site plumbing. The pump-driven espresso machine is considered an improvement from the piston-driven espresso machines.
Steam-Driven Espresso Machines
The very first espresso machines (espresso coffee makers) used steam pressure, and today many lower cost espresso machines are steam driven. Steam-driven units are also attached to drip filter coffee makers for home use.
Piston-Driven Espresso Machines
The piston-driven espresso machine is an espresso machine is powered by the operator (e.g., the barista) pumping a lever which pressurizes the hot water to force it through roasted, ground coffee to brew the espresso.
These lever-style espresso machines are where the term “pulling an espresso shot” came from since the barista had to pull the long handle.
Piston-driven machines may be spring piston machines in which the user's efforts create tension on a spring which then in turn creates the pressure to push the water through the grounds or manual piston machines in which the user's pulling of the lever directly pushes the water through the coffee grounds to brew the espresso.
Air-Pump Espresso Machines
The air-pump espresso machine, which is the newest type of espresso machine commercially available, uses compressed air to create the pressure necessary to force the water through the roasted, ground coffee to brew the espresso.
With an air-pump espresso machine, the user provides the hot water either fresh off the stove or from a previously prepared thermos. The compressed air may be produced by an electric air compressor, N2O or CO2 cartridges, or a hand pump.
Air-pump espresso machine are usually very small and light making them more portable than other types of espresso machines, which typically require electricity.
Super Automatic Espresso Machines
Super automatic espresso machines typically have a built-in coffee grinder and will dose, tamp, and brew the espresso as well as eject the spent puck of coffee grounds, requiring the operator (e.g., barista) only to push a button. Some models of super automatic espresso machines are also able to steam milk.
Commercial Espresso Machines
A commercial espresso machine is designed to be extremely durable while producing large quantities of espresso in a commercial establishment such as a coffeehouse or restaurant. Prosumer espresso machines have some of the attributes of a commercial machine though are designed for only light commercial use.
Home Espresso Machines
Home espresso machines (consumer espresso machines) are designed for home use and typically get water from a reservoir in the espresso maker. The higher end models like the Saeco Exprelia Evo and Saeco GranBaristo have full adjustment capabilities - from drink size to quantity of espresso used and milk frothing capabilities. When looking for a quality espresso machine, these should be the go-to option.
Pod Espresso Machines
A pod espresso machine is designed for use with an espresso pod consisting of roasted and ground coffee pre-pressed into a puck shape and contained within perforated filter paper to fit into a pod portafilter for brewing the espresso.
Filter pod technology was first developed in 1959 by K. Cyrus Melikian who worked in Pennsylvania for Automatic Brewers and Coffee Devices. Later an Italian company and other companies were granted licenses for pod technology and soon began to create standards for pod-related products.
Easy Serving Espresso Pods
The Illy Company developed the Easy Serving Espresso (E.S.E.) design and standards in 1998. This is an open design in order to encourage adaptation and compatibility.
Today many espresso machines (espresso coffee makers), including espresso machine brands other than Illy, accommodate the use of either a 45 mm, 7 gram pod (e.g., ESE Pod) or hand tamped coffee grounds.
The Espresso Machine Portafilter
An important part of any espresso machine (espresso coffee maker) is the portafilter (filterholder; groupo) which holds the filter basket(s) that hold the roasted, ground coffee during the brewing of the espresso.
Portafilters are typically constructed from chrome-coated brass or copper, aluminum, or steel. A portafilter may have two spouts that the espresso pours out from, and a handle usually made of wood or another heat-resistant material.
The portafilter is designed to easily clamp and unclamp from the espresso machine's group (brewhead; delivery group) which usually sticks out the front of the espresso machine.
The Espresso Machine Control Panel
The control panel of an espresso machine (espresso maker) serves as the control center and includes some or all of the following knobs and/or switches: power, steam control, brew control, and hot water dispensing. Switches may be push-button, rocker type, or pressure sensitive.
What is Pre Infusion?
Pre Infusion is a feature on some automatic espresso machines and super automatic espresso machines and involves pre-wetting the bed of roasted, ground, tamped coffee within the filter basket and portafilter before beginning the actual espresso brewing process.
Pre Infusion is typically accomplished by the espresso machine's pump sending water onto the bed of tamped coffee for one to two seconds, followed by a brief pause, after which the pump again activates and completes the brewing of the espresso shot(s).
What is Progressive Preinfusion?
Progressive Preinfusion, also called natural preinfusion, is a feature on the E61 grouphead and also involves pre-wetting the bed of roasted, ground coffee that is tamped into the filter basket and portafilter of an espresso machine.
Progressive preinfusion is considered by many to be the best method of extracting all of the best flavor components. In progressive preinfusion, the espresso machine's pump activates to fill a secondary chamber before the full pressure of brewing is applied to the coffee bed.
The result is three to seven seconds of saturation time for the tamped coffee before the full brewing pressure (e.g., 135 pounds per square inch) is effected to complete the brewing of the espresso.
A Brief History of Espresso Machines
A prototype of the espresso machine was first invented in France in 1822. In 1905, the first commercial espresso machine was manufactured in Italy, and in 1933, the first automatic espresso machine was invented by Dr. Ernest Lily.
In 1946, the espresso machine was somewhat perfected by an Italian named Achilles Gaggia who used a piston and a spring-powered lever system to create high pressure for extraction to brew espresso. This method produced a thick layer of crema, the top foamy layer containing the coffee's best flavors and aromatic properties.
The first pump-driven espresso machine was invented by the Faema Company in 1960. Faema stands for Fabbrica Apparecchiature Elettromeccaniche e Affini, a company that was founded by Carlo Ernesto Valente in Italy in 1945.
Faema originally produced, in the 1950s, the type of piston-lever espresso machines (with a horizontal boiler) that were fairly common at the time. Then in 1961 Faema developed an espresso machine that used a mechanical pump, rather than a piston lever, to create the pressure to brew the espresso.
Priding itself on technological innovation, Faema became a major producer of espresso machines. The company was also a symbol of Italy's post-war boom in production.
Espresso Machines Today
Today, prominent companies producing espresso machines (commercial espresso machines and home espresso machines) and single serve coffee brewers (single cup coffee brewers), pod coffee makers, and pod espresso machines that may brew coffee pods, espresso pods, or coffee K-Cups K-Cups include Green Mountain Coffee Roasters (Green Mountain coffee k cups), Cuisinart (single serve brewing system), Gaggia (Gaggia espresso and espresso machines), Timothy's World Coffee (Timothy's K Cups), Lavazza (Lavazza espresso), Krups (Krups espresso machine) DeLonghi (DeLonghi espresso machine), Keurig (Keurig coffee K-Cups), Braun (T-Disc single serve coffee maker), Saeco (Saeco espresso), Tassimo (Suprema single serve system coffee makers and espresso makers using T-Discs), Illy (Easy Serving Espresso Pods), Gevalia (Signature blend T discs), Cuisinart (single serve brewing system), and Senseo which offers Senseo coffee pods and the Senseo coffee pod system.
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