How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to create 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 making drip coffee but the difference is in the pressure.

The Head of the Group

The name implies, the group head is the place you put your portafilter in when brewing espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure of the extraction. There are numerous kinds of group heads each with distinct advantages and drawbacks. Some are focused on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. Some have a combination, like the E61. This is a very popular choice for Coffeee baristas as it provides a variety of advantages in one package.

As you can see in the above image the group head comes with numerous notches that you can place your portafilter before twisting it with your hands to lock it in. A gasket of rubber is situated inside the notches to help create a seal while you insert your portafilter. The notches allow for an exact placement of the portafilter. This is essential for an accurate extraction.

The group head not only allows you to put in your portafilter easily, but it also maintains the temperature at a constant level. This is done by cycling hot water around the portafilter and through the brew-basket, ensuring that the temperature is constant for extraction. This is vital, because just a few degrees could make the difference between a excellent and great espresso.

The Pump

In contrast to manual piston machines which use a lever to pressurize water, the rotary espresso machines use motorized pumps to deliver the nine atmospheric bars of pressure necessary for espresso extraction. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be less expensive than piston-driven machines, and tend to last longer. However, both types of machine can get damaged through overuse and lack of cleaning. They also make mechanically complex and can lead to an expensive price for even the most basic models.

Certain espresso machines utilize steam pressure instead of a pump for brewing espresso. The downside is that the same boiler that produces steam also increases the temperature of the water until it reaches boiling, which can lead to over-extraction. They also have to continuously rebuild their pressure between cups. This takes energy and time.

Many espresso machines use an rotary or a vibration pump. A vibration model utilizes a rotating disk to generate pressure, while the rotary model pushes hot water through the ground at a fast speed. Both machines produce great espresso but rotary machines are more quiet, durable and less likely to fail.

The Boiler

The boiler is the part that heats the water to the optimal temperature for extraction. The resultant steam then reaches the portafilter that contains the ground espresso and is then pumped into the cup. During this process, the steam creates pressure that pushes through the grounds of the coffee. This results in a whipped-up top of the espresso. This is the hallmark of a good espresso.

There are three types of espresso machines, each with different pumps and the temperature of the brew. There are a variety of ways that the brew can be controlled, as well as the dimensions of the cup the machine can produce.

The first espresso machines were steam-types. The first espresso machines were steam-type machines. The coffee tasted bitter and burnt. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp your beans yourself, but the pump regulates the flow of water and pressure. This is an excellent combination of human control and mechanised accuracy.

The Filter

Espresso machines typically use a filter that separates the coffee grounds from the hot water. The filter is also a vital component of the temperature control system because it stops the machine from overheating.

It also enhances flavor as a filter can allow for a longer bloom time. This helps the beans to release their nuances and gives an opportunity for better extraction.

However it is crucial to keep in mind that even a high-quality filter can produce a bad cup of coffee, because the quality of the beans and extraction is still essential.

This is where the magic happens, it's the thing that makes an espresso really taste great. The grouphead (also known as the brewhead) is where you place the portafilter, the thingy that you use to put the coffee grounds in, when making buy espresso machines.

In a 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 a high pressure. These kinds of machines are typically cheaper and easier to maintain than pump-driven models. However, they are limited in their ability to create the ideal conditions for brewing since they operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.

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