How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the coffee we love. How does it work exactly?

To make an espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However, it is the pressure that makes the main difference.

The Head of the Group

The group head is the portafilter that you insert when brewing espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure that results from the extraction. There are a variety of group heads each with its own advantages and drawbacks. Some are designed for temperature stability while others are built to handle pre-infusion. Some are designed to control the lever. Some come with a combination of both, like the E61. This is a favorite among baristas because it offers multiple benefits in a single package.

As you can see from the above photo the group head has a number of notches. The portafilter is placed inside these notches, and then turn the head around to secure it. A rubber gasket is located in the notches to create a seal while you insert your portafilter. The notches on the head allow for an exact placement of the portafilter, which is crucial to ensure a consistent extraction.

In addition to allowing you easily insert your portafilter, the group head is also responsible for maintaining a consistent temperature. It does this by circulating hot water through the brew basket and around the portafilter, ensuring that it is always at the right temperature for extraction. It is important to note that even a slight differences can make the distinction between a great and a excellent espresso.

The Pump

Unlike manual piston machines, which rely on a lever to pressurize water, rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure that are required for espresso extraction. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically more affordable and last longer than piston-driven machines. However, both types of machines are susceptible to degrading due to excessive use and insufficient cleaning. They also add mechanical complexity, which can result in the cost of even the simplest models.

Some espresso machines employ steam pressure instead of a pump for brewing espresso. This could lead to over-extraction since the boiler that makes steam also causes the water to boil. Additionally, these machines frequently have to restore their pressure between cups, which requires time and energy.

Many espresso machines make use of an rotary or a vibration pump. A vibration model makes use of a vibrating disk to generate pressure, while the rotary model pushes hot water through the ground at a rapid speed. Both types of machines can produce an excellent espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the component that heats the water to the optimal temperature to extract. The resulting steam reaches the portafilter containing the ground espresso coffee and is then pumped into the cup. During this process, the steam causes pressure to push through the coffee grounds. This results in a crema on top espresso machines of the espresso. This is a hallmark of a great espresso.

There are three kinds of espresso makers, which differ in the type of pump they employ and the degree of heat that 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 earliest espresso machines were steam-based. They used only one boiler to make both steam and brew, however, the pressure they could produce was very low - just two bars of atmospheric pressure at most. The coffee tasted bitter and burned. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso machine with grinder maker is a semi-automatic device with an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the flow of water and pressure. This is a great compromise between the human touch and the mechanised accuracy.

The Filter

Espresso machines usually have filters that separate the grounds of the coffee from the hot water. The filter is also a vital element of the machine's temperature control, as it prevents overheating.

It also aids in flavor, since a filter lets you enjoy a longer bloom phase. This lets the beans release their flavor and also allows for better extraction.

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

This is where the magic happens, it's what makes an espresso really taste good. The grouphead (also known as the brewhead) is where you place the portafilter, the thingy that you put the grounds of coffee into while making espresso.

Steam-driven espresso machines use hot water that is heated in an airtight container to produce steam. The steam then pushes hot water into the grounds of coffee at high end espresso machine pressure. These kinds of machines are generally less expensive and easier to maintain than pumps-driven models. They are however limited for creating the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

In recent years, compressed air-driven espresso machines have been gaining popularity. They use an air compressor to force hot water through grounds and are much more portable than electric steam-driven machines.