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How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly does it work?

In order to make espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee for espresso machine but the major difference is in the pressure.

The Head of the Group

The group head is the portafilter that you put in when making espresso. It is responsible for dispersing the water into the portafilter before controlling the pressure of the extraction. There are a variety of group heads each with their own advantages and drawbacks. Some are focused on temperature stability, while others on pre-infusion features, and others are designed to control the lever. Some include a mix of features, like the E61 one, which is the most popular choice among baristas for its ability to offer multiple perks in a single package.

As you can see from the image above the group head is fitted with several notches. It is possible to place your portafilter in these notches, then twist the head to secure it. There is also a gasket of rubber in the notches, which helps create the seal when you insert your portafilter into the machine. The notches allow for the precise placement of the portafilter. This is crucial for an efficient extraction.

In addition to allowing you easily connect your portafilter, the group head is also responsible for maintaining an even temperature. It does this by cycling hot water through the brew container and around the portafilter, ensuring 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 decent espresso machine and a great espresso.

The Pump

The motorized pumps that are used in espresso machines that rotate provide the nine atmospheric bar pressure required for espresso extraction. This is different from manual piston machines that use levers. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are generally less expensive and last longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of frequent use and inadequate cleaning. Pumps are also more complex mechanically, and can add to the cost of even the simplest models.

Some espresso machines can eliminate the pump entirely and utilize steam pressure to make espresso capsule machine. This can result in over-extraction because the boiler that makes steam also heats the water to boil. In addition these machines are often required to rebuild their pressure between cups, which takes time and energy.

Many espresso machines use either a vibration or rotary pump. A vibration model uses the vibrating disk to create pressure, whereas the rotary model pushes hot water through the ground at high speed. Both types of machine can produce an excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is used to heat the water to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter containing ground espresso beans and is then pumped down into the cup. The steam causes pressure to push through the coffee grounds. This creates a foam on top of the professional espresso maker. This is the hallmark of a great espresso.

There are three types of espresso makers, which differ in the kind of pump they use and the degree of heat that the espresso is. There are many ways to control the brew and the size of the cup that can be made by the machine.

The first espresso machines were steam-types. They employed one boiler to make both steam and brew however the pressure they were able to produce was very low - just two bars of atmospheric pressure at most. This led to the coffee tasting bitter and burnt. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most commonly used espresso machine is a semiautomatic that has an electric pump. These are what people imagine when they think of an espresso maker. With a semi-automatic espresso machine, you have to grind the beans and then tamp them by hand. The pump regulates the flow of water and pressure. This is a great solution that combines human control with mechanised reliability.

The Filter

Typically, espresso machines use filters to separate the coffee grounds as they pass through the hot water. The filter is also a vital component of the temperature control system as it prevents the machine from overheating.

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

It is important to remember that even the finest filter could result in a poor cup of coffee. The quality of the beans and the extraction process are still very important.

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

In an espresso machine that is driven by steam, hot water is heated in an airtight container to produce steam, which is then pushed through the grounds under high pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

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