How Does Machine Espresso Work?

The machine espresso uses precise pressure, as well as a filtering technology that is amazing to create the coffee you love. What exactly is it that makes it work?

In order to make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee. However, espresso makers it is the pressure that makes the main difference.

The Group Head

As the name suggests, the group head is where you insert your portafilter when making espresso. It disperses the water into the portafilter, and then regulates the pressure during the extraction. There are a variety of group heads each with distinct advantages and drawbacks. Some focus on temperature stability, while others on pre-infusion options, and others are designed to control the lever. There are some that contain a variety of features, such as the E61, which is considered to be the most popular among baristas due to its capacity to offer multiple benefits in a single package.

As you can see from the photo above the group head has a number of notches. It is possible to place your portafilter in these notches and then twist the head to secure it. A rubber gasket is located inside the notches to help create a seal as you insert your portafilter. The notches on the head permit a precise positioning of the portafilter which is essential to ensure an efficient extraction.

The group head is not just able to allow you to place your portafilter easily however, it also keeps a constant temperature. It does this by cycling hot water through the brew container and around the portafilter, making sure that it's always at the right temperature to extract. This is important, as even a small difference in temperature can be the difference between a good and great espresso.

The Pump

In contrast to manual piston machines which rely on a lever that pressurize water, Rotary espresso machine with milk frother machines rely on motorized pumps to supply the nine atmospheric bars of pressure required to extract espresso. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be less expensive than piston-driven models, and they tend to last longer, but both types of machines could be damaged by excessive use and inadequate cleaning. They also create mechanical complexity and can lead to a high price tag on even the simplest models.

Some espresso machines employ steam pressure instead of a pump to brew espresso. The drawback is that the boiler that produces steam also increases the temperature of the water until it reaches boiling and can result in excessive extraction. In addition these machines are often required to rebuild their pressure between cups, which takes time and energy.

A majority of espresso machines use an rotary or vibrating pump, with a vibrating model that uses a vibrating disc to create the pressure and an rotary model that pushes hot water through the grounds at high speed. Both types of machine can make a great espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the one that heats the water to the right temperature to extract. The resulting steam is then transferred to the portafilter which holds the ground espresso and gets funnelled down into the cup. During this process, steam creates pressure and pushes through the coffee grounds. This results in a layer crema that is then poured over. This is one of the hallmarks of a good 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 different ways to control the brew as well as the size of cup that can be produced by the machine.

The earliest espresso machines were steam type. They used only one boiler to make both steam and brew but the pressure they could create was minimal - two bars of atmospheric pressure maximum. The coffee tasted bitter and burned. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most commonly used espresso machine is a semiautomatic one with an electric pump. These are the things people think of when they think of an espresso machine. With a semi-automatic machine, you have to grind the beans and then tamp them yourself but the pump controls the flow of water and pressure. This is a fantastic solution that combines human control with mechanised consistency.

The Filter

Espresso machines typically use filters that separate the grounds of the coffee from hot water. The filter is also an essential part of the machine's temperature control, since it helps to prevent overheating.

It also improves flavor as a filter lets you enjoy a longer bloom time. This helps the beans to release their flavors and provides an opportunity to improve extraction.

However, it is important to keep in mind that even a great filter can result in a poor cup of coffee, as the quality of the beans and extraction is essential.

It's in this area that the magic happens. This is the reason why espresso tastes so good. The grouphead, also called the brewhead, is where the portafilter (the thing you put the coffee machine espresso ground into) sits when you're making espresso.

In the steam-driven espresso machine hot water is heated in an airtight tank to create steam. This is then pushed through the grounds at high pressure. These kinds 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 only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

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