How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the coffee and espresso machine we love. What exactly does it work?

In order to make espresso, hot water is pushed under 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

As the name suggests the group head is where you insert your portafilter when making espresso. It disperses the water into the portafilter and controls the pressure of the extraction. There are a variety of group heads, each with its own advantages and disadvantages. Some are specifically designed for the stability of temperature while some are built to handle pre-infusion. Others are built to control the lever. Some are a combination, like the E61. This is a very popular choice for baristas because it offers multiple advantages in one package.

As you can see in the image above the group head is made up of numerous notches that you can place your portafilter and twist it by hand to secure it. A gasket made of rubber is positioned inside the notches to help create a seal as you insert your portafilter. The notches allow for precise placement of your portafilter. This is crucial for an even extraction.

The group head is not just able to allow you to insert your portafilter easily however it also keeps a constant temperature. It does this by circulating hot water through the brew pan and around the portafilter, making sure that it is always at the right temperature to extract. This is important because even a few degrees can make the difference between a good and great espresso.

The Pump

The motorized pumps used in rotary compact espresso machine machines supply the nine atmospheric bar pressure needed to extract espresso. This differs from manual piston machines which use a lever. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger before being pushed through the ground coffee in the group head.

Pumps tend to be less expensive than piston-driven Machines espresso machines, and tend to last longer, but both types of machines may degrade with overuse and insufficient cleaning. Pumps are also more complex mechanically, which can raise the cost of even the simpler models.

Certain espresso machines can eliminate the pump completely and instead make use of steam pressure to make espresso. This can lead to over-extraction as the boiler that makes steam also causes the water to boil. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

Many espresso machines make use of the rotary or vibration pump. A vibration model employs a vibrating disk to generate pressure, while a Rotary model pushes hot coffee through the ground at high speed. Both machines can produce excellent espresso, but rotary machines are more quiet, durable and less likely to break down.

The Boiler

The boiler is the one that is used to heat the water to the ideal temperature for extraction. The steam that is produced reaches the portafilter, which contains the ground espresso and is then pumped into the cup. The steam creates pressure that pushes through the coffee grounds. This results in a layer crema that is then poured over. This is one of the main characteristics of a great cheap espresso machine.

There are three types of espresso makers, and they differ in the kind of pump they use and how hot the brew is. There are different ways in which the brew can be controlled and the size of the cup that the machine can make.

The first espresso machines were steam-type. The first espresso machines were steam-type machines. This resulted in the coffee tasting bitter and burnt. This is the reason Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machines home machine.

The most common espresso machine is a semiautomatic with an electric pump. These are what people imagine when they imagine an espresso machine. With a semi-automatic espresso machine, you grind the beans and tamp them by hand. However, the pump regulates the flow of water and pressure. This is a great combination of human control and mechanised accuracy.

The Filter

Typically, espresso machines use filters to separate the grounds of the coffee as they go through the hot water. The filter is also an essential element of the machine's temperature control, as it helps prevent overheating.

It also improves flavor, as a filter allows for a more prolonged bloom time. This lets the beans release their flavor and improves extraction.

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

This is where the magic happens, it's the thing that makes an espresso really taste good. The grouphead, also referred to as the brewhead, is where the portafilter (the thing you put the ground coffee in) is placed when you're making espresso.

In an best home espresso machine machine that is driven by steam, hot water is heated in an airtight container to create steam. This then pushes the hot water through the grounds at high pressure. These machines are less expensive and easier for the user to 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 years, compressed air-driven espresso machines have been gaining popularity. They utilize an air compressor to force hot water through grounds, and are far more portable than steam-driven electric machines.