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How Does Machine Espresso Work?

The machine espresso utilizes precise pressure and filtering technology that is amazing to create the coffee you enjoy. But how exactly does it work?

Espresso is made by pushing hot water under high pressure through finely-ground coffee. The process is similar to that of making drip coffee. However, the pressure is the major difference.

The Group Head

As the name suggests, the group head is where you place your portafilter while making espresso. It disperses water into the portafilter, and regulates the pressure of the extraction. There are many different kinds of group head each with its own advantages and drawbacks. Some focus on temperature stability, others on pre-infusion options, and others are designed to control the lever. Some include a combination such as the E61. This is a preferred choice for baristas due to the fact that it has multiple advantages in a single package.

As you can see in the image above the group head is fitted with a variety of notches. You place your portafilter in these notches, then turn the head around to secure it. There is also a gasket of rubber which is located inside the notches, which helps create a seal when you insert your portafilter into the machine. The notches permit precise placement of the portafilter. This is essential for an even extraction.

The group head does not just allow the portafilter to be inserted easily however, it also keeps an even temperature. It does this by cycling hot water through the brew basket and around the portafilter, making sure that it is always at the right temperature for extraction. It is important to realize that even a few degree deviation can make the difference between a good and a great espresso.

The Pump

Unlike manual piston machines, that use a lever to pressurize water, rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure needed to extract espresso. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger prior to being pushed through the ground coffee in the group head.

Pumps tend to be less expensive and last longer than piston-driven machines. However, both types of machines can degrade because of frequent use and insufficient cleaning. They also increase the complexity of mechanical systems, which can result in costly prices for even the most basic models.

Certain espresso machines remove the pump completely and make use of steam pressure to make pro espresso machine. The drawback of this is that the boiler that produces steam also raises the temperature of the water to the point of boiling which could lead to over-extraction. Additionally these machines typically have to restore their pressure between cups, which requires time and energy.

Many espresso machines utilize either a rotary or vibration pump, with a vibrating model using a rotating disc to generate the pressure and an rotary model that pushes hot water through the grounds under high speed. Both machines can produce excellent espresso but rotary machines are more stable, quieter and less likely to break down.

The Boiler

The boiler is the one that makes the water warm to the ideal temperature to extract. The steam that is produced reaches the portafilter, which contains the ground espresso and is then pumped down into the cup. The steam causes pressure to push through the grounds of the coffee. This creates a crema on top of the espresso. This is one of the hallmarks of a good espresso.

There are three distinct types of espresso machines, each with distinct pumps and the temperature of the brew. There are many ways to control the strength of the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam-based. The first espresso machines were steam-type machines. This resulted in the coffee and espresso maker tasting bitter and burnt. This is why Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most well-known espresso maker is a semi-automatic machine with an electric pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp the beans on your own, but the pump regulates the flow of water and pressure. This is a great compromise between human control and mechanized reliability.

The Filter

Typically, espresso machines employ a filter to separate out the coffee grounds as they pass through the hot water. The filter is also an essential part of the temperature control system as it keeps the machine from overheating.

A filter can also help with flavor as it allows for a longer flowering phase. This lets the beans release their nuances, and allows for a better extraction.

However it is crucial to keep in mind that even a good filter could result in a bad cup of coffee, as the quality of the beans and extraction is crucial.

This is where the magic happens, and it's what makes espresso taste great. The grouphead, also referred to as the brew head, is the place where the portafilter (the device you put the ground coffee in) sits when you're making espresso.

Steam-driven espresso machines use hot water heated in an airtight container to make steam. The steam then pushes hot water through the grounds of coffee under high pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. They are however limited in their ability for creating the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

In recent years, compressed air-pump-driven espresso machines espresso machines have become more popular. They make use of an air compressor to force hot water into the ground. They are also more mobile than electric steam-driven espresso coffee machine machines.