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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the perfect cup of coffee. What exactly is it that makes it work?

Espresso is made by forcing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee, but the key difference is in the pressure.

The Group Head

The group head is the portafilter you insert when brewing espresso. It is responsible for dispersing water into the portafilter before controlling the pressure of the resulting extraction. There are many different types of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, others on pre-infusion capabilities, while others are designed to control the lever. Some have a combination, such as the E61. This is a preferred choice for baristas as it provides a variety of advantages in a single package.

As you can see from the image above the head of the group is equipped with several notches. The portafilter is placed in these notches and then twist the head to secure it. There is also a gasket made from rubber that is a part of the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches allow for precise placement of your portafilter. This is essential for an even extraction.

Aside from allowing you to easily insert your portafilter, the group head is also responsible to maintain an even temperature. This is done by cycling hot water around the portafilter, and through the brew basin, ensuring the temperature is always right for extraction. This is vital, because even a small difference in temperature can mean the difference between good and great espresso.

The Pump

In contrast to manual piston machines which rely on a lever that pressurize water, rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure necessary for espresso extraction. The pressure is created by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pumped through the ground coffee in the group head.

Pumps are generally less expensive than piston-driven models, and they tend to last longer, but both types of machines may get damaged through overuse and lack of cleaning. They also increase the complexity of mechanical systems and can lead to a high price tag on even the simplest models.

Certain espresso machines remove the pump entirely and utilize steam pressure to make espresso. This can lead to over-extraction as the boiler that makes steam also heats the water to boil. These machines also have to constantly rebuild their pressure in between cups. This requires energy and time.

Many espresso machines utilize the rotary or vibration pump, which is a vibration model that uses a vibrating disc that generates the pressure and the rotary model pushing hot water through the grounds at high speed. Both types of machine can make excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler heats the water to the ideal temperature to extract. The resulting steam reaches the portafilter that contains the ground espresso coffee, and is then funneled down into the cup. During this process the steam creates enough pressure to push the grounds of coffee through. This creates a foam on the top of the espresso. This is one of the hallmarks of a good espresso.

There are three types of uk espresso machine machines, each having different pumps and the temperature of the brew. There are a variety of ways that the brew may be controlled, as well as the dimensions of the cup the maker can create.

The earliest espresso machines were steam-based. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burnt. This is why the Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most well-known espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp your beans yourself The pump, however, regulates the flow of water and pressure. This is a great compromise between the human touch and the mechanized consistency.

The Filter

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

It also improves flavor, since a filter can allow for a longer bloom time. This allows the beans to release their flavor and improves 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, remain vital.

It's here that the magic occurs. This is what makes espresso taste so delicious. The grouphead (also called the brewhead) is where you place the portafilter, the device used to place the coffee grounds in, while making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to produce steam. The steam then pushes hot water through the grounds of coffee at high pressure. These machines are cheaper and easier for espresso machines the user to maintain than pumps-driven models. However, they are limited in their ability to provide the perfect conditions for brewing, since they are only operating at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.

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