How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to create the coffee we love. What exactly does it work?

To make an espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.

The Head of the Group

The group head is the portafilter you put in when making espresso coffee machine. It disperses water into the portafilter, and then regulates the pressure of the extraction. There are many different types of group heads each with their own advantages and disadvantages. Some are designed to provide the stability of temperature while some are built to handle pre-infusion. Others are built to control the lever. Some come with a combination of both, such as the E61. This is a popular choice among baristas since it provides multiple benefits in a single package.

As you can see in the photo above, the group head has several notches to place your portafilter before twisting it with your hands to lock it in. There is also a gasket made from rubber which is located inside the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches on the head permit an exact positioning of the portafilter which is crucial to ensure an efficient extraction.

In addition to allowing you to easily insert your portafilter, the group head is responsible for maintaining an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket to ensure the temperature is always right for extraction. This is vital, because even a few degrees can make the difference between a good and great espresso.

The Pump

Unlike manual piston machines, which rely on a lever to pressurize water, rotating espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure required for espresso extraction. The pressure is created by removing tap water from a reservoir, and pumping it through a heat exchanger before being shot through the best ground coffee for espresso machine coffee inside the group head.

Pumps tend to be less expensive than piston-driven machines, and they tend to last longer. However, both types of machines can degrade with overuse and insufficient cleaning. Pumps are also more complicated mechanically, which can raise prices of even most basic models.

Certain espresso machines utilize steam pressure instead of a pump in order to brew espresso. This could lead to over-extraction since the boiler that makes steam also causes the water to boil. These machines also have to continually rebuild their pressure between cups. This requires energy and time.

Many espresso machines make use of an rotary or vibrating pump, which has a vibration model using a vibrating disc to create pressure, and rotating models that push hot water through the grounds at high speed. Both types of machines can make excellent espresso, but the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the one that makes the water warm to the ideal temperature to extract. The steam produced will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. It is then poured into the cup. During this process, steam creates pressure to push through the grounds of the coffee. This results in a layer crema that is then poured over. This is one of the main characteristics of a good espresso.

There are three kinds of espresso makers, Federatedjournals post to a company blog,, and Espresso makers they differ in the kind of pump they use and how hot the espresso is. There are various ways to control the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam-types. They utilized a single 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. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso machine is a semiautomatic one with an electric pump. When people think of espresso machines, they imagine these machines. With a semi-automatic machine you need to grind the beans and tamp them yourself but the pump regulates the flow of water and pressure. This is a great compromise between the human touch and the mechanized accuracy.

The Filter

Typically, espresso machines espresso machines use filters that separate the grounds of the coffee as they go through the hot water. The filter is also an essential element of the temperature control system, as it prevents the machine from overheating.

A filter can also help with flavor because it allows for the beans to flower for a longer period of time. This helps the beans let their nuances out and espresso makers provides an opportunity to improve extraction.

It is important to remember that even the most efficient filter can produce a bad cup of coffee. The quality of the beans and the extraction, remain vital.

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

In the steam-driven espresso machine hot water is heated in an airtight tank to create steam. Steam then pushes the hot water through the grounds at high pressure. They are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the perfect brewing conditions since they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars.

In recent years, compressed air-driven espresso machines have become more popular. They use an air-compressor to force hot water through the ground. They are also more mobile than steam-driven electric espresso machines.