How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to make the perfect cup of coffee. How exactly does it work?

Espresso is produced by pushing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee but the difference is in the pressure.

The Head of the Group

As the name suggests the group head is the place you place your portafilter while making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the extraction. There are a variety of types of group head each with its distinct advantages and drawbacks. Some focus on temperature stability, others on pre-infusion capabilities, while others are designed to control the lever. There are some that have a combination of features, such as the E61 one, which is to be the most popular among baristas due to its ability to provide multiple benefits in one package.

As you can see in the image above, the group head has many notches in which you can place your portafilter and twist it by hand to secure it. There is also a rubber gasket that resides inside the notches and helps create a seal when you insert your portafilter into the machine. The notches on the head allow for an exact placement of the portafilter, which is vital to ensure an even extraction.

The group head not only allows 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's always at the correct temperature to extract. It is important to realize that even a few degree differences can make the distinction between a good and excellent espresso.

The Pump

In contrast to manual piston machines which rely on a lever to pressurize water, the rotary espresso machines use motorized pumps to supply the nine atmospheric bars of pressure necessary for espresso extraction. The pressure is created by pumping water through a heat exchanger and then through the ground coffee.

Pumps are typically more affordable and last longer than piston-driven machines. However, both kinds of machines may degrade due to overuse and inadequate cleaning. They also create mechanical complexity that can lead to the cost of even the most basic models.

Some espresso machines employ steam pressure instead of a pump in order to brew espresso coffee machine. This could lead to over-extraction since the boiler that produces steam also heats the water to boil. In addition these machines typically have to rebuild their pressure between cups, which requires time and energy.

A majority of espresso machines utilize an rotary or a vibration pump. A vibration model employs an oscillating disk to create pressure, while a rotating model pushes hot water through the ground at a rapid speed. Both machines can make excellent espresso but rotary machines are more stable, quieter and less likely to fail.

The Boiler

The boiler is the part that heats water to an ideal temperature for extraction. The steam that is produced gets to the portafilter which contains the espresso coffee grounds. The steam is then channeled into the cup. During this process, steam creates pressure to push through the coffee grounds. This creates a crema on top of the espresso. This is a sign of a good espresso.

There are three types of espresso makers, and they differ in the type of pump they employ and the degree of heat that the espresso is. There are different ways in which the brew could be controlled and the dimensions of the cup the machine can make.

The first espresso machines were steam-types. They utilized one boiler to make both steam and brew but the pressure they could produce was very low - just two bars of atmospheric pressure maximum. This resulted in the coffee tasting bitter and burnt. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most popular espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic espresso machine, you have to grind the beans and then tamp them by hand, but the pump is able to regulate the flow of water and pressure. This is an excellent solution that combines human control with mechanized accuracy.

The Filter

Espresso machines usually use filters that separate the coffee grounds from the hot water. The filter is also an essential component of the machine's temp control, since it stops overheating.

It also helps with flavor as a filter allows for a more prolonged bloom time. This allows the beans to release their flavors and provides an opportunity for a better extraction.

However it is crucial to remember that even a high-quality filter could result in a bad cup of coffee, since the quality of the beans and extraction are vital.

It's in this area that the magic takes place. This is the reason why espresso tastes so good. The grouphead, often referred to as the brew head, is where the portafilter (the thingy you put the ground coffee into) sits when you're making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to make steam. The steam then moves hot water through the grounds of coffee under high pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the ideal conditions for brewing since they are only operating at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.

In recent years, compressed air pump-driven espresso machines have become more popular. They utilize an air compressor to push hot water through the ground and are more mobile than steam-driven electric espresso machines.