How Does Machine Espresso Work?

The machine espresso is made using precise pressure, as well as a filtering system that is awe-inspiring to create the coffee you enjoy. What exactly does it work?

To make espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, but the major difference is in the pressure.

The Head of the Group

The name implies the group head is the place you put your portafilter in when making espresso. It is responsible for dispersing the water into the portafilter before controlling the pressure that results from the extraction. There are numerous kinds of group heads, each with its own advantages and drawbacks. Some are specifically designed for the stability of temperature while some are specifically designed to handle pre-infusion. Others are built to control the lever. Some have a combination, such as the E61. This is a very popular choice for baristas since it provides multiple advantages in a single package.

As you can see in the photo above, the group head is equipped with several notches. The portafilter is placed in these notches, then twist the head to secure it. A gasket made of rubber is placed in the notches to create a seal while you insert your portafilter. The notches on the head allow for an exact position of the portafilter which is crucial for an even extraction.

In addition to allowing you to effortlessly insert your portafilter the group head is also responsible to maintain an even temperature. It does this by circulating hot water through the brew pan and around the portafilter, ensuring that it is always at the correct temperature to extract. This is crucial, since even a few degrees can mean the difference between good and excellent espresso.

The Pump

Unlike manual piston machines, which rely on a lever to pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure needed for espresso extraction. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger before being pumped through the ground coffee in the group head.

Pumps tend to be cheaper than piston-driven machines, and they tend to last longer. However, both types of machines could become damaged due to excessive use and poor cleaning. They also increase the complexity of mechanical systems that can lead to the cost of even the most basic models.

Some espresso machines employ steam pressure instead of a pump to make espresso. This could lead to over-extraction since the boiler that makes steam also warms the water to boil. These machines also have to continuously rebuild their pressure between cups. This requires energy and time.

Many espresso machines utilize a vibration or rotary pump, which is a vibration model that uses a vibrating disc to create the pressure and an rotary model that pushes hot water through the grounds under high speed. Both models can make a great espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the part which heats the water to the optimal temperature for extraction. The steam that is produced is then directed to the portafilter, which holds the espresso grounds. The steam is then channeled into the cup. In this process, the steam creates pressure to push through the grounds of the coffee. This results in a whipped-up the top of the espresso. This is one of the main characteristics of a good espresso.

There are three different types of espresso machines, each with different pumps and the temperature of the brew. There are various ways that the brew can be controlled, as well as the size of the cup that the machine is capable of making.

The first espresso machines were steam-types. They had one boiler to create both steam and brew, modern but the pressure they could produce was not very high - two bars of atmospheric pressure, at most. This led to the coffee espresso machines tasting burnt and bitter. This is why Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most well-known espresso maker is a semi-automatic device that has an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp the beans on your own while the pump controls the flow of water and pressure. This is a great compromise between the human touch and the mechanised consistency.

The Filter

Espresso machines usually have filters that separate the grounds of coffee from hot water. The filter is also a crucial component of the temperature control system, as it keeps the machine from overheating.

It also improves flavor, as a filter allows for a longer bloom phase. This lets the beans release their nuances, and allows for a better extraction.

It is important to remember that even the best filter can result in a bad cup of coffee. The quality of the beans and modern the extraction process, remain crucial.

It's in this area that the magic takes place. This is what makes espresso taste so delicious. The grouphead (also called the brewhead) is where you place the portafilter, the thingy used to place the coffee grounds in, when making espresso.

Steam-driven espresso machines use hot water that is heated in an airtight vessel to create steam. The steam then moves hot water through the grounds of coffee under high pressure. These kinds of machines are typically less expensive and simpler to maintain than pumps-driven models. They are however limited to create the perfect 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 have been gaining popularity. They utilize an air compressor to push hot water across the ground. They are also more mobile than steam-driven electric espresso coffee maker machines.