How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. But how exactly does it work?

To make espresso, hot water is pushed under 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 implies the group head is the place you place your portafilter while brewing espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure that results from the extraction. There are many different types of group heads, each with its own advantages and drawbacks. Some are specifically designed for temperature stability while others are specifically designed to handle pre-infusion. Others are built to control the lever. Some include a mix of features, like the E61, which is considered the classic choice among many baristas due to its capacity to provide multiple benefits in one package.

As you can see in the image above, the group head is fitted with a variety of notches. It is possible to place your portafilter into these notches and turn the head around to secure it. A gasket of rubber is situated inside the notches to help create a seal as you insert your portafilter. The notches on the head permit an exact location of the portafilter which is essential to ensure an efficient extraction.

The group head not only allows you to place your portafilter easily however it also keeps an even temperature. It does this by cycling hot water through the brew container and around the portafilter to ensure that it's always at the right temperature for extraction. This is crucial, since even a small difference in temperature can be the difference between a excellent and great espresso.

The Pump

The motorized pumps used in professional espresso machine for home machines that rotate provide the nine atmospheric bar pressure required for espresso extraction. This differs from manual piston machines that use levers. The pressure builds up 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 may degrade due to excessive use and insufficient cleaning. Pumps are also more complex mechanically, which can raise the cost of even simplest models.

Some espresso machines remove the pump completely and instead make use of steam pressure to make espresso. This can result in over-extraction because the boiler that produces steam also heats the water to boil. Additionally these machines typically have to rebuild their pressure between cups, which requires time and energy.

A majority of espresso machines utilize a rotary or vibration pump. A vibration model uses a rotating disk to generate pressure, whereas the rotary model pushes hot water through the ground at a rapid speed. Both types of machines can make excellent espresso, but rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is what is used to heat the water to the 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, the steam creates pressure to push through the grounds of the coffee. This results in a crema on top of the espresso. This is one of the hallmarks of a great espresso.

There are three kinds of espresso makers, which differ in the type of pump they employ and how hot the espresso is. There are various ways that the brew may be controlled and the size of the cup the machine can produce.

The earliest discount Espresso machines machines were steam-based. They had one boiler to make both brew and steam, but the pressure they could generate was low - only two bars of atmospheric pressure at the most. This resulted in the coffee tasting burnt and bitter. This is the reason Milanese producers Luigi Bezzerra and Desiderio Pavoni developed 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. Semi-automatic machines require you to grind and tamp the beans yourself while the pump controls the flow of water and pressure. This is an excellent compromise between human touch and the mechanised accuracy.

The Filter

Espresso machines usually have filters that separate the grounds of the coffee from the hot water. The filter is also a vital part of the machine's temperature control, as it helps prevent overheating.

It also enhances flavor, as it lets you enjoy a longer bloom phase. This helps the beans to release their flavors and provides the chance for better extraction.

It is important to remember that even the best cheap espresso machine filter can produce a bad cup of coffee. The quality of the beans and the extraction process are still very important.

This is where the magic happens, it's the thing that makes espresso taste great. The grouphead (also known as the brewhead) is where you place the portafilter - the thingy that you use to put the coffee grounds into, while making espresso coffee machine for home.

In an espresso machine that is driven by steam, hot water is heated in an airtight tank to produce steam, which then pushes the hot water through the grounds at high pressure. These types of machines are generally cheaper and easier to maintain than pumps-driven models. They are however limited for creating the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

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