Notes

The Ugly Reality About Machine Espresso
How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and amazing filter technology to make the delicious coffee we enjoy. How exactly does it work?

To make an espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the main difference.

The Head of the Group

As the name suggests, the group head is where you put your portafilter in when making espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the resulting extraction. There are numerous kinds of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, while others on pre-infusion capabilities, while others are designed to control the lever. There are even some that come with a range of features, like the E61, which is considered to be the most popular among baristas due to its ability to offer multiple benefits in a single package.

As you can see in the image above The group head features many notches in which you can place your portafilter before twisting it manually to secure it. A gasket made of rubber is positioned inside the notches to help make a seal when you insert your portafilter. The notches on the head permit an exact placement of the portafilter, which is necessary to ensure an efficient extraction.

Apart from allowing you easily insert your portafilter, the group head is also responsible for maintaining an even temperature. This is done by cycling hot water around the portafilter and through the brew-basket, ensuring that the temperature is constant for extraction. This is crucial, since just a few degrees could mean the difference between good and great espresso.

The Pump

The motorized pumps in espresso machines that rotate provide the nine atmospheric bar pressure that is required for espresso extraction. This differs from manual piston machines that use a lever. The pressure builds by drawing tap water from a reservoir and pumping it through a heat exchanger prior being shot through the ground coffee in the group head.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both types of machines are susceptible to degrading due to excessive use and inadequate cleaning. They also make mechanically complex that can lead to costly prices for even the most basic models.

Some espresso machines make use of steam pressure instead of a pump in order to brew espresso. This can lead to over-extraction as the boiler that makes steam also heats the water to boil. The machines also need to constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines utilize a vibration or rotary pump, which is a vibration model using a rotating disc that generates the pressure, and a rotary model pushing hot water through the grounds at high speed. Both machines can make excellent espresso, however 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 holds the espresso grounds. It is then funneled into the cup. The steam is able to create enough pressure to push the grounds of coffee through. This results in a layer crema on top. This is a sign of a good espresso.

There are three types of espresso machines, each having different types of pumps and the temperature of the brew. There are different ways to control the brew and the size of the cup that can be made by the machine.


The first espresso machines were steam-type. The first espresso machines were steam types. This led to the coffee tasting bitter and burnt. This is why Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most commonly used espresso machine is a semiautomatic that has an electric pump. When people think of espresso machines, they think of these machines. With a semi-automatic espresso machine, you have to grind the beans and then tamp them yourself but the pump regulates the flow of water and pressure. This is a perfect combination of human control and mechanised reliability.

The Filter

Espresso machines typically use a filter that separates the grounds of the coffee from the hot water. The filter is also a crucial part of the temperature control system as it keeps the machine from overheating.

A filter also improves flavor since it allows for a longer flowering phase. This allows the beans to let their nuances out and provides an opportunity to improve extraction.

However espresso machine uk is crucial to remember that even a top filter could result in a bad cup of coffee, as the quality of the beans and extraction is still vital.

It's here that the magic happens. This is what makes espresso taste so good. The grouphead, also referred to as the brewhead, is where the portafilter (the thing you put the ground coffee in) is located when you're making espresso.

Steam-driven espresso machines make use of hot water heated in an airtight container to make steam. The steam then pushes hot water through the grounds of coffee at high pressure. These kinds of machines are typically less expensive and easier 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 perfect shot requires 9-10 bars.

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

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