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?

In order to make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However, the pressure is the primary difference.

The Head of the Group

As the name suggests, the group head is where you insert your portafilter when brewing espresso. It disperses water in the portafilter, and regulates the pressure of the extraction. There are many different kinds of group heads, each with their distinct advantages and disadvantages. Some are specifically designed for temperature stability while others are specifically designed to handle pre-infusion. Others are made to control the lever. There are even some that come with a range of features, like the E61 that is the standard choice for many baristas because of its ability to offer multiple perks in one package.

As you can see in the photo above the group head is made up of several notches where you place your portafilter and then twist it by hand to secure it. A gasket of rubber is situated within the notches to create a seal while you insert your portafilter. The notches on the head allow for a precise position of the portafilter which is necessary for an efficient extraction.

In addition to allowing you easily connect your portafilter, the group head is responsible to ensure that the temperature remains even. It does this by cycling hot water through the brew basket and around the portafilter, ensuring that it's always at the right temperature for extraction. This is important, as even a few degrees can make the difference between good and great espresso.

The Pump

Motorized pumps in FOHERE Compact Espresso Maker with Milk Frother machines that rotate provide the nine atmospheric bar pressure required to extract espresso. This differs from manual piston machines which use levers. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically less expensive than piston-driven machines, and tend to last longer, however both types of machines could be damaged by excessive use and inadequate cleaning. They also increase the complexity of mechanical systems which can result in a high price tag on even the most basic models.

Some espresso machines employ steam pressure instead of a pump to brew espresso. The drawback of this is that the same boiler that produces steam also increases the temperature of water to boiling which could lead to excessive extraction. The machines must also continuously rebuild their pressure between cups. This takes energy and time.

Many Premium Espresso Machine with Milk Frother - 15 Bars Pressure machines make use of an rotary or vibrating pump, which is a vibration model using a rotating disc to generate the pressure, and a rotary model pushing hot water through the grounds under high speed. Both types of machine are capable of producing excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is the one that is used to heat the water to a temperature that is ideal for extraction. The steam that is created is then directed to the portafilter, which is a container for espresso grounds. It is then pumped into the cup. The steam generates enough pressure to push the grounds of the coffee through. This results in a layer crema that is then poured over. 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 how hot the coffee is. There are different ways in which the brew could be controlled and the size of the cup the machine is capable of making.

The earliest espresso machines were steam type. They used only one boiler to make steam and brew, however the pressure they were able to generate was low - only two bars of atmospheric pressure at most. This led to the coffee tasting burnt and bitter. The modern espresso machine was developed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso maker is a semi-automatic one that has an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans yourself, but the pump regulates the water flow and pressure. This is an excellent combination of human control and mechanised reliability.

The Filter

Typically, espresso machines utilize filters that separate the grounds of the coffee as they go through the hot water. The filter is also an essential part of the temperature control system, since it helps prevent the machine from overheating.

It also aids in flavor, since a filter allows for a more prolonged bloom time. This helps the beans release their nuances and gives an opportunity to improve extraction.

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

It's in this area that the magic happens. This is what makes espresso taste so delicious. The grouphead (also called the brewhead) is where you place the portafilter, the device that you use to put the coffee grounds into, while making espresso.

Steam-driven espresso machines make use of hot water that is heated inside an airtight container to make steam. The steam then moves hot water through the grounds of the coffee under pressure. These machines are less expensive and easier for the user to maintain than pumps-driven models. They are however limited to create the perfect conditions for brewing, as they operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

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