How Does Machine Espresso Work?

Machine espresso employs precise pressure and incredible filter technology to produce the delicious coffee we enjoy. What exactly does it work?

Espresso is made by pushing hot water under high pressure through finely-ground coffee and espresso machine. The process is similar to making drip coffee machines espresso, but the major difference is in the pressure.

The Group Head

The group head is the portafilter that you put in when making espresso. It disperses the water into the portafilter, and regulates the pressure of the extraction. There are numerous kinds of group heads each with their own advantages and disadvantages. Some focus on temperature stability, some on pre-infusion capabilities, and still others are designed to control the lever. Some are a combination, such as the E61. This is a very popular choice for baristas since it provides multiple benefits in a single 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 then twist it manually to secure it. There is also a gasket of rubber that is a part of the notches and helps create an airtight seal when you insert your portafilter into the machine. The notches on the head permit a precise placement of the portafilter, which is crucial to ensure an even extraction.

Apart from allowing you easily place your portafilter in, 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, ensuring that it is always at the right temperature for extraction. It is important to realize that even a slight difference can make the difference between a decent and a great espresso.

The Pump

Motorized pumps in espresso machines rotary provide nine atmospheric bar pressure needed to extract espresso. This is different from manual piston machines which use a lever. The pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger before being pushed through the ground coffee inside the group head.

Pumps are typically cheaper and last longer than piston-driven machines. However, both types of machines can deteriorate due to excessive use and insufficient cleaning. They also add mechanical complexity that can lead to an expensive price for even the most basic models.

Certain espresso machines eliminate the pump entirely and utilize steam pressure to make espresso. This can result in over-extraction because the boiler that produces steam also causes the water to boil. The machines must also continually rebuild their pressure between cups. This takes energy and time.

A majority of espresso machines use either a rotary or vibration pump, which is a vibration model using a vibrating disc that generates the pressure, and a rotary model pushing hot water through the grounds under high speed. Both types of machine are capable of producing excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is the part that heats water to an optimal temperature for extraction. The resulting steam reaches the portafilter containing ground espresso coffee machine home 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 of crema that is then poured over. This is one of the main characteristics of a good espresso.

There are three kinds of home espresso machine machines, each with different types of pumps and brew temperature. There are various ways that the brew can be controlled and the size of the cup that the machine is capable of making.

The first espresso machines were steam-types. They employed 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. This resulted in the coffee tasting bitter and burnt. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most popular espresso machine is a semiautomatic that has an electric pump. These are the things people think of when they think of an espresso machine. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the water flow and pressure. This is a fantastic solution that combines human control with mechanised consistency.

The Filter

Typically, espresso machines use filters that separate the grounds of the coffee as they go through the hot water. The filter is also a vital component of the machine's temperature control, as it prevents overheating.

It also helps with flavor, as a filter allows for a more prolonged bloom time. This helps the beans let their nuances out and provides an opportunity for a better extraction.

However it is crucial to keep in mind that even a great filter could result in a bad cup of coffee, because the quality of the beans and extraction is still important.

It's in this area that the magic occurs. This is the reason why espresso tastes so good. The grouphead, also referred to as the brew head, is the place where the portafilter (the device you put the coffee grounds into) is placed when you're making espresso.

In a steam-driven professional espresso machine for home machine, hot water is heated in an airtight container to produce steam, which is then pushed through the grounds at high pressure. These machines are cheaper and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the ideal conditions for brewing because they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

In recent years, espresso machines driven by compressed air-pump have become increasingly popular. They utilize an air compressor to force hot water through the ground. They are also more mobile than electric steam-driven espresso machines.