How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to make the coffee we love. What exactly is it?

Espresso is created by forcing hot water 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

As the name implies the group head is where you insert your portafilter when brewing espresso. It disperses water in the portafilter, and then regulates the pressure during the extraction. There are numerous kinds of group heads each with their own advantages and disadvantages. Some are specifically designed for temperature stability while others are specifically designed to handle pre-infusion. Others are made to control the lever. Some include a combination such as the E61. This is a popular choice among baristas due to the fact that it has multiple benefits in a single package.

As you can see from the image above the head of the group is fitted with a variety of notches. It is possible to place your portafilter inside these notches, and then turn the head around to secure it. There is also a rubber gasket that is a part of the notches and helps to create an airtight seal after inserting your portafilter into the machine. The notches on the head allow for a precise placement of the portafilter, which is crucial to ensure a consistent extraction.

In addition to allowing you to 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 pan and around the portafilter, making sure that it's always at the right temperature to extract. It is crucial to keep in mind that even a few degree differences can make the distinction between a good and great espresso.

The Pump

In contrast to manual piston machines that use a lever to pressurize water, rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure needed to extract espresso. The pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger prior being pumped through the ground coffee in the group head.

Pumps are generally less expensive and last longer than piston-driven machines. However, both types of machines can degrade due to excessive use and insufficient cleaning. Pumps are also more complicated mechanically, and can add to the price of even the simple models.

Certain espresso machines utilize steam pressure instead of a pump in order to brew espresso. This can lead to over-extraction as the boiler that makes steam also causes the water to boil. In addition these machines are often required to restore their pressure between cups, which requires time and energy.

A large majority of espresso machines employ the rotary or vibration pump. A vibration model employs a vibrating disk to generate pressure, whereas a rotary model pushes hot water through the ground at a fast speed. Both machines produce great espresso however rotary machines tend to be more quiet, durable and less likely to fail.

The Boiler

The boiler is the part that heats the water to the ideal temperature to extract. The resultant steam then reaches the portafilter containing ground espresso beans and is then pumped down into the cup. During this process, steam creates pressure that pushes through the grounds of the coffee. This results in a layer crema on top. This is the hallmark of a good barista espresso machine.

There are three kinds of espresso makers, and they differ in the kind of pump they use and how hot the brew is. There are many ways to control the amount of brew, as well as the size of the cup that can be produced by the machine.

The first espresso machines were steam-types. They had one boiler to create steam and brew, however the pressure they were able to produce was not very high - two bars of atmospheric pressure at the most. This resulted in the coffee tasting burnt and bitter. This is the reason Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most common espresso maker is a semi-automatic device with an electric pump. When people think of espresso machines, they think of these machines. If you have a semi-automatic machine you need to grind the beans and then tamp them by hand, but the pump controls the flow of water and pressure. This is a fantastic combination of human control and mechanized reliability.

The Filter

Typically, espresso machines employ a filter to separate out the grounds of coffee and espresso maker when they pass through the hot water. The filter is also a vital component of the machine's temperature control, as it helps prevent overheating.

It also aids in flavor, as it allows for a longer bloom phase. This allows the beans to release their flavor and improves extraction.

However, it is important to keep in mind that even a good filter can make a terrible cup of coffee, since the quality of the beans and extraction are important.

This is where the magic happens, it's the thing that makes best cheap espresso machine taste great. The grouphead, also referred to as the brewhead, is where the portafilter (the thingy you put the ground coffee in) sits when you're making espresso.

Steam-driven espresso machines use hot water heated in an airtight vessel to create steam. The steam then pushes hot water through the grounds of coffee under high pressure. These machines are less expensive and are easier for espressomachines the user best bean to cup espresso machine maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

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