How Does Machine Espresso Work?

The machine espresso uses precision pressure, and a filtering system that is awe-inspiring to make the coffee you enjoy. How does it work exactly?

Espresso is created by forcing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee, but the major difference is in the pressure.

The Group Head

As the name suggests, the group head is where you put your portafilter in when making espresso. It disperses water into the portafilter, and regulates the pressure of the extraction. There are several different types of group heads each with its unique advantages and disadvantages. Some are designed for stability of temperature while others are specifically designed to handle pre-infusion. Some are designed to control the lever. Some have a combination, like the E61. This is a very popular choice for baristas as it provides a variety of benefits in one package.

As you can see in the image above, the group head has a number of notches. You place your portafilter inside these notches, and then twist the head to secure it. There is also a gasket of rubber in the notches to help create an airtight seal after inserting your portafilter into the machine. The notches on the head allow for a precise positioning of the portafilter which is vital to ensure a consistent extraction.

The group head does not just allow the portafilter to be inserted easily but also maintains the same temperature. It does this by circulating hot water through the brew pan and around the portafilter, ensuring that it's always at the right temperature to extract. This is important, as even a few degrees can mean the difference between good and excellent espresso.

The Pump

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

Pumps are typically less expensive and last for longer than piston-driven machines. However, both kinds of machines can degrade because of frequent use and inadequate cleaning. Pumps are also more complex mechanically, which could increase the price of even the simple models.

Some espresso machines use steam pressure instead of a pump for brewing espresso. This could lead to over-extraction since the boiler that makes steam also warms the water to boil. In addition these machines typically have to rebuild their pressure between cups, which requires time and energy.

Many espresso machines make use of an rotary or a vibration pump. A vibration model uses a vibrating disk to generate pressure, while a rotating model pushes hot water through the ground at a fast speed. Both models can make a great espresso, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is what is used to heat the water to the right temperature for extraction. The steam that is created gets to the portafilter which holds the espresso grounds. The steam is then channeled into the cup. The steam creates enough pressure to push the grounds of coffee through. This results in a layer of crema on top espresso machines. This is a sign of a good espresso.

There are three kinds of espresso makers, which differ in the kind of pump they use and how hot the brew is. There are also different ways in which the brew can be controlled and the size of the cup the machine can produce.

The first espresso machines were steam-based. The earliest espresso machines were steam types. This led to the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso machine is a semiautomatic one with an electric pump. When people think of espresso machines, they think of these machines. With a semi-automatic machine you need to grind the beans and tamp them by hand, but the pump provides regulated water flow and pressure. This is a great combination of human control and mechanised reliability.

The Filter

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

It also enhances flavor as a filter allows for a more prolonged bloom time. This allows the beans to release their flavor and improves extraction.

However, it is important to keep in mind that even a high-quality filter can produce a bad cup of coffee, since the quality of the beans and extraction is crucial.

It's here that the magic happens. This is what makes espresso taste so good. The grouphead, sometimes referred to as the brew head, is where the portafilter (the container you place the ground coffee in) is placed when you're making buy espresso makers.

Steam-driven espresso machines use hot water that is heated in an airtight vessel to create steam. The steam then pushes hot water through the grounds of the coffee under pressure. These kinds of machines are generally less expensive and easier to maintain than pumps-driven models. They are however limited in their ability to create the perfect brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent times, espresso machines powered by a compressed air compressor have become increasingly popular. They make use of an air compressor to push hot water through the ground and are much more mobile than electric steam-driven espresso machines.