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How Does Machine Espresso Work?

The machine espresso uses precise pressure and filter technology that is mind-blowing to create the coffee you love. How exactly does it work?

Espresso is made by pushing hot water at high pressure through finely ground coffee and espresso machine. The process is similar to that of making drip coffee. However it is the pressure that makes the main difference.

The Group Head

The group head is the portafilter that you put in when making espresso. It disperses the water into the portafilter, and regulates the pressure during the extraction. There are many different types of group heads each with its own advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. Some are a combination, such as the E61. This is a very popular choice for baristas because it offers multiple benefits in one package.

As you can see in the image above the head of the group is equipped with several notches. It is possible to place your portafilter into these notches and turn the head around to secure it. A gasket made of rubber is positioned inside the notches to help create a seal while you insert your portafilter. The notches on the head allow for an exact location of the portafilter which is crucial for a consistent extraction.

The group head not only lets you to put in your portafilter easily however, it also keeps an even temperature. It does this by circulating hot water through the brew basket and around the portafilter, making sure that it is always at the correct temperature to extract. It is crucial to keep in mind that even a few degree difference can make the difference between a good and great espresso.

The Pump

Unlike manual piston machines, that use a lever to pressurize water, the rotary espresso machines use motorized pumps to deliver the nine atmospheric bars of pressure required to extract espresso. This pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger before being pushed through the ground coffee inside the group head.

Pumps are typically less expensive than piston-driven models, and they tend to last longer, however both types of machines can degrade with overuse and insufficient cleaning. They also make mechanically complex which can result in costly prices for even the most basic models.

Certain espresso machines utilize steam pressure instead of a pump in order to brew espresso. The drawback is that the same boiler that produces steam also increases the temperature of water to the point of boiling and can result in over-extraction. The machines must also constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines make use of a rotary or vibration pump. A vibration model utilizes the vibrating disk to create pressure, while the circular model pushes hot liquid through the ground at high speed. Both machines can make great espresso but rotary machines are more stable, quieter and less likely to break.

The Boiler

The boiler is what is used to heat the water to a temperature that is ideal for extraction. The steam created will eventually reach the portafilter, which holds the espresso grounds. It is then pumped into the cup. The steam generates enough pressure to push the coffee machines espresso grounds through. This results in a whipped-up the top espresso machines of the espresso coffee maker. This is one of the main characteristics of a great compact espresso machine.

There are three types of espresso makers. They differ in the type of pump they employ and how hot the coffee is. There are a variety of ways to control the strength of the brew and the size of cup that can be produced by the machine.

The first espresso machines were steam-types. They utilized a single boiler to make both steam and brew however the pressure they were able to produce was very low - just two bars of atmospheric pressure at most. This led to the coffee tasting burnt and bitter. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso maker is a semi-automatic one with an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic machine you have to grind the beans and tamp them by hand. The pump provides regulated water flow and pressure. This is a great compromise between the human touch and mechanized quality.

The Filter

Typically, espresso machines employ filters that separate the grounds of coffee when they pass through the hot water. The filter is also a vital part of the machine's temperature control, as it prevents overheating.

A filter can also help with flavor since it allows for an extended flowering time. This allows the beans to release their flavors and provides the chance for better extraction.

It is important to keep in mind that even the most efficient filter can produce a bad cup of coffee. The quality of the beans and the extraction, are still very important.

This is where the magic happens, and it's what makes an espresso machine small really taste good. The grouphead (also known as the brewhead) is where you put the portafilter, the device that you use to put the coffee grounds in, when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. This then pushes the hot water through the grounds at high pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent years, espresso machines powered by compressed air-pump have become increasingly popular. They utilize an air compressor to force hot water through the grounds and are much more portable than steam-driven electric machines.