How Does Machine Espresso Work?

Machine espresso uses precision pressure and incredible filter technology to produce the coffee we love. But how exactly does it work?

Espresso is made by forcing hot water at high pressure through finely ground coffee. The process is similar to that of making drip coffee. However the pressure is the main difference.

The Head of the Group

The group head is the portafilter is inserted when you are making espresso. It is responsible for dispersing water into the portafilter, and controlling the pressure that results from the extraction. There are numerous kinds of group heads, each with its own advantages and drawbacks. Some are designed for stability in temperature, while others are designed to handle pre-infusion. Others are made to control the lever. Some come with a combination of both, such as the E61. This is a popular choice among baristas because it offers multiple advantages in one package.

As you can see from the picture above, the group head is equipped with several notches. You can place your portafilter in these notches, then twist the head to secure it. There is also a rubber gasket in the notches to help create the seal when you insert your portafilter into the machine. The notches on the head permit an exact location of the portafilter which is necessary for a consistent extraction.

In addition to allowing you easily insert your portafilter, the group head is also responsible to maintain an even temperature. It does this by cycling hot water through the brew basket and around the portafilter to ensure that it's always at the right temperature for extraction. It is crucial to keep in mind that even a tiny variation can mean the difference between a good and a excellent espresso.

The Pump

In contrast to manual piston machines which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure that are required for espresso extraction. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.

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 prices of even simple models.

Some espresso machines make use of steam pressure instead of a pump for brewing espresso. The downside is that the same boiler that produces steam also increases the temperature of water to boiling which could lead to excessive extraction. In addition these machines are often required to restore their pressure between cups, which takes time and energy.

Many espresso maker for home machines utilize the rotary or vibration pump, which is a vibration model using a vibrating disc to generate the pressure, and an rotary model that pushes hot water through the grounds under high speed. Both types of machines can make excellent espresso, but Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler makes the water warm to the perfect temperature for extraction. The steam that is produced gets to the portafilter which holds the espresso grounds. It is then funneled into the cup. The steam creates pressure that pushes through the coffee grounds. This results in a layer of crema that is then poured over. This is a hallmark of a great espresso.

There are three kinds of espresso makers, which differ in the kind of pump they use and the degree of heat that the coffee is. There are also different ways that the brew can be controlled, as well as the size of the cup that the machine can make.

The first espresso machines were steam-based. They used a single boiler to make steam and brew, however, the pressure they could create was minimal - two bars of atmospheric pressure, at most. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was invented by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso machine is a semiautomatic one with an electric pump. This is what people envision when they think of an espresso machine. With a semi-automatic machine, you must grind the beans and tamp them by hand. The pump regulates the flow of water and pressure. This is a great solution that combines human control with mechanized reliability.

The Filter

Espresso machines usually have a filter that separates the grounds of the coffee from the hot water. The filter is also a vital component of the machine's temp control, since it stops overheating.

It also helps with flavor, as a filter can allow for a longer bloom time. This lets the beans release their flavor and improves extraction.

It is important to keep in mind that even the most efficient filter can produce a bad cup of coffee. The quality of the beans, and Machine Espresso the extraction process, are still crucial.

It's here that the magic occurs. This is what makes espresso taste so delicious. The grouphead (also known as the brewhead) is where you place the portafilter - the thingy used to place the grounds of coffee into when making espresso.

In an espresso machine that is driven by steam, hot water is heated in an airtight tank to create steam. This is then pushed through the grounds with high pressure. These kinds of machines are typically less expensive and simpler to maintain than pump-driven models. However, they are limited in their capacity to create the ideal brewing conditions, as they only operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.

In recent years, compressed-air-pump-driven espresso machines have been gaining popularity. They use an air compressor to push hot water across the ground and are much more mobile than electric steam-driven espresso machines.