How Does Machine Espresso Work?

Machine espresso machine with frother makes use of precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. How exactly does it work?

To make espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, however the main difference lies in the pressure.

The Group Head

The group head is the portafilter that you insert when brewing espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure of the extraction. There are many different types of group heads each with its own advantages and drawbacks. Some are designed for stability of temperature while others are designed to handle pre-infusion. Others are built to control the lever. There are also some that come with a range of features, such as the E61 one, which is the classic choice among many baristas due to its ability to offer multiple perks in a single package.

As you can see in the photo above the group head comes with many notches in which you can put your portafilter, then twist it by hand to secure it. A gasket of rubber is situated in the notches to create a seal as you insert your portafilter. The notches permit the precise placement of the portafilter. This is crucial for an accurate extraction.

The group head not only lets you to place your portafilter easily, but it also maintains the temperature at a constant level. It does this by cycling hot water through the brew container and around the portafilter to ensure that it is always at the correct temperature to extract. This is vital, because just a few degrees could make 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 machines rely on motorized pumps to deliver the nine atmospheric bars of pressure that are required to extract espresso. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger prior being shot through the ground coffee inside the group head.

Pumps are typically less expensive and last for longer than piston-driven machines espresso. However, both types of machines can deteriorate because of frequent use and insufficient cleaning. Pumps are also more complex mechanically, which can raise the cost of even most basic models.

Some espresso machines can eliminate the pump entirely and employ steam pressure to create espresso. The drawback is that the same boiler that produces steam also raises the temperature of water to boiling which could lead to excessive extraction. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

A majority of espresso maker for Home machines utilize either a vibration or rotary pump. A vibration model utilizes a rotating disk to generate pressure, whereas a circular model pushes hot liquid through the ground at high end espresso machine speed. Both types of machines 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 a temperature that is ideal to extract. The steam that is created will eventually reach the portafilter, which is a container for espresso grounds. It is then funneled into the cup. During this process the steam causes enough pressure to push the coffee grounds through. This results in a crema on top of the espresso. This is a sign of a great espresso.

There are three types 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 and the size of the cup that can be produced by the machine.

The earliest buy espresso machines machines were steam-based. They used only one boiler to make both steam and brew however, the pressure they could produce was not very high - two bars of atmospheric pressure maximum. The coffee tasted bitter and burnt. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most commonly used espresso maker is a semi-automatic machine that has an electric pump. These are the things people think of when they imagine an espresso machine. If you have a semi-automatic machine you must grind the beans and tamp them by hand, but the pump regulates the flow of water and pressure. This is a fantastic compromise between human control and mechanised accuracy.

The Filter

espresso machines for home machines typically use filters that separate the grounds of the coffee from hot water. The filter is also a crucial element of the temperature control system, as it keeps the machine from overheating.

Filters also aid in flavor as it allows for a longer flowering period. This lets the beans release their nuances, and allows for better extraction.

However, it is important to keep in mind that even a top filter could result in a bad cup of coffee as the quality of the beans and extraction is still important.

It's in this area that the magic takes place. This is what makes espresso taste so good. The grouphead (also called the brewhead) is where you put the portafilter, which is the thingy used to place the coffee grounds into, when making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to create steam. The steam then pushes hot water through the grounds of the coffee under pressure. These types of machines are generally less expensive and easier to maintain than pump-driven models. However, they are limited in their ability to produce the perfect conditions for brewing, because they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars.

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