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How Does Machine Espresso Work?

The machine espresso utilizes precision pressure, and a filtering system that is awe-inspiring to make the coffee you enjoy. What exactly does it work?

In order to make espresso home machine hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.

The Head of the Group

As the name suggests the group head is the place you place your portafilter while brewing espresso. It distributes water into the portafilter, and then regulates the pressure of extraction. There are numerous kinds of group heads each with its own advantages and disadvantages. Some are specifically designed for stability of temperature while others are built to handle pre-infusion. Others are built to control the lever. Some have a combination, like the E61. This is a favorite among baristas because it offers multiple advantages in a single package.

As you can see in the above image the group head comes with several notches to place your portafilter and then twist it with your hands to secure it. A gasket of rubber is situated within the notches to create a seal as you insert your portafilter. The notches allow for an exact placement of the portafilter. This is essential for an accurate extraction.

Aside from allowing you to easily insert your portafilter, the group head is responsible to ensure that the temperature remains even. This is achieved by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is at the right level for extraction. This is important because even a few degrees can be the difference between a good and great espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, Rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure necessary for espresso extraction. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger prior it is shot through the ground coffee in the group head.

Pumps are typically less expensive than piston-driven models, and they tend to last longer, however both types of machines espresso machines may get damaged through overuse and lack of cleaning. Pumps are also more complicated mechanically, which can increase prices of even most basic models.

Some espresso machines employ steam pressure instead of a pump for brewing espresso. This can lead to over-extraction as the boiler that produces steam also causes the water to boil. Additionally the machines often have to restore their pressure between cups, which takes time and energy.

Many espresso machines make use of an rotary or vibrating pump, which has a vibration model that uses a vibrating disc that generates the pressure and a rotary model pushing hot water through the grounds under high speed. Both types of machines can produce an excellent espresso, however Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is what heats the water to the ideal temperature to extract. The steam produced reaches the portafilter, which is the container that holds the espresso coffee grounds. It is then pumped into the cup. During this process, steam creates pressure that pushes through the grounds of the coffee. This results in a layer of crema on top. This is a sign of a good espresso.

There are three distinct types of espresso machines, each with different pumps and the temperature of the brew. There are different ways to control the brew as well as the size of the cup that can be produced by the machine.

The first espresso machines were steam-type. They used one boiler to make both steam and brew however, the pressure they could produce was very low - just two bars of atmospheric pressure maximum. This resulted in the coffee tasting burnt and bitter. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern mini espresso machine machine.

The most well-known espresso maker is a semi-automatic device that has an electric pump. These are what people imagine when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans yourself however the pump controls the water flow and pressure. This is a great solution that combines human control with mechanized reliability.

The Filter

Typically, Travel Espresso Maker machines use a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also an essential element of the temperature control system as it prevents the machine from overheating.

A filter also helps with flavor since it allows for the beans to flower for a longer period of time. This helps the beans release their nuances and gives an opportunity to improve extraction.

However it is crucial to remember that even a top filter can produce a bad cup of coffee, as the quality of the beans and extraction are vital.

This is where the magic happens, it's what makes espresso taste great. The grouphead, sometimes called the brewhead, is where the portafilter (the device you put the coffee for espresso machine grounds into) sits when you're making espresso.

Steam-driven espresso machines use hot water that is heated in an airtight container to create steam. The steam then moves hot water through the grounds of coffee at high pressure. They are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the ideal brewing conditions, because they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

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