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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. How does it work exactly?

Espresso is produced by pushing hot water under pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the primary difference.

The Group Head

The group head is the portafilter you insert when brewing espresso. It disperses the water into the portafilter, and regulates the pressure of the extraction. There are numerous kinds of group heads each with its own advantages and disadvantages. Some focus on temperature stability, others on pre-infusion capabilities, and still others are designed to control the lever. There are even some that come with a range of features, such as the E61, which is considered the classic choice among many baristas due to its capacity to offer multiple perks in one package.

As you can see in the above image the group head comes with several notches to place your portafilter before twisting it manually to secure it. There is also a gasket made from rubber which is located inside the notches and helps create an airtight seal after inserting your portafilter into the machine. The notches permit an exact placement of the portafilter. This is essential for a consistent extraction.

In addition to allowing you to effortlessly insert your portafilter the group head is responsible for maintaining an even temperature. This is done by cycling hot water around the portafilter, and through the brew basin, ensuring that the temperature is at the right level for extraction. It is important to remember that even a slight differences can make the distinction between a great and a excellent espresso.

The Pump

Contrary to manual piston machines which rely on a lever to pressurize water, rotating espresso machines espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure necessary for espresso extraction. The pressure is created by removing tap water from a reservoir, and pumping it through a heat exchanger prior to being pumped through the ground coffee inside the group head.

Pumps are generally cheaper and machine espresso last longer than piston-driven machines. However, both kinds of machines can degrade because of frequent use and insufficient cleaning. Pumps are also more complicated mechanically, which can increase the cost of even the simple models.

Certain espresso machines remove the pump completely and use steam pressure to brew espresso. The drawback is that the boiler that produces steam also raises the temperature of the water to the point of boiling, which can lead to over-extraction. Additionally, these machines frequently have to rebuild their pressure between cups, which requires time and energy.

Many espresso machines use an rotary or a vibration pump. A vibration model employs a rotating disk to generate pressure, whereas the Rotary model pushes hot coffee through the ground at a high speed. Both types of machine can make excellent espresso, however Rotary machines 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 steam that is produced reaches the portafilter, which contains the ground espresso coffee, and is then pumped into the cup. During this process the steam generates enough pressure to push the grounds of coffee for espresso machine through. This creates a foam on top of the espresso. This is one of the hallmarks of a good espresso.

There are three types of espresso makers, which differ in the type of pump they use and the degree of heat that the coffee is. There are different ways in which the brew could be controlled, as well as the size of the cup the maker can create.

The first espresso machines were steam-types. The first espresso machines were steam-type machines. The coffee tasted bitter and burnt. This is the reason why Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most common espresso machine is a semiautomatic model with an electric pump. These are the things people think of when they think of an espresso maker. With a semi-automatic espresso machine, you need to grind the beans and tamp them yourself but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and mechanized accuracy.

The Filter

Typically, espresso machines have a filter to separate out the grounds of coffee as they move through the hot water. The filter is also an essential component of the machine's temp control, since it helps to prevent overheating.

It also improves flavor, since a filter can allow for a longer bloom phase. This helps the beans to let their nuances out and provides the chance for better extraction.

It is important to remember that even the most efficient filter can produce a bad cup of coffee. The quality of the beans, as well as the extraction, are still crucial.

This is where the magic happens, it's the thing that makes an espresso really taste great. The grouphead (also known as the brewhead) is where you put the portafilter - the thingy which you put the grounds of your coffee into while making espresso.

In a steam-driven espresso machine hot water is heated in an airtight container to produce steam, which then pushes the hot water through the grounds at a high pressure. These kinds of machines tend to be less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to create the ideal brewing conditions, since they are only operating at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.

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