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How Does Machine Espresso Work?

The machine espresso uses precise pressure, as well as a filtering technology that is amazing to create the coffee you enjoy. What exactly is it that makes it work?

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

The Head of the Group

The group head is the portafilter you place in the espresso maker when making it. It disperses water into the portafilter, and regulates the pressure during the extraction. There are a variety of group heads each with their own advantages and disadvantages. Some are focused on temperature stability, some on pre-infusion features, and others are designed to control the lever. Some come with a combination of both, like the E61. This is a preferred choice for baristas due to the fact that it has multiple benefits in a single package.

As you can see in the above image the group head comes with several notches to place your portafilter and twist it manually to secure it. There is also a gasket of rubber which is located inside the notches and helps create an airtight seal when you insert your portafilter into the machine. The notches on the head permit a precise positioning of the portafilter which is crucial to ensure an efficient extraction.

Apart from allowing you easily place your portafilter in, the group head is responsible to ensure that the temperature remains even. It does this by circulating hot water through the brew basket and around the portafilter, ensuring that it's always at the correct temperature to extract. This is important, as even a few degrees can mean the difference between good and excellent espresso.

The Pump

Unlike manual piston machines, which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure that are required to extract espresso. 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 generally less expensive than piston-driven models, and they tend to last longer, although both types of machine can get damaged through overuse and lack of cleaning. Pumps are also more complex mechanically, which can raise the price of even the simple models.

Some espresso machines employ steam pressure instead of a pump for brewing espresso. This can result in over-extraction because the boiler that makes steam also causes the water to boil. Additionally these machines typically have to restore their pressure between cups, which requires time and energy.

Many espresso machines use a rotary or vibration pump. A vibration model makes use of a vibrating disk to generate pressure, while a Rotary model pushes hot coffee through the ground at high speed. Both machines produce great espresso, however rotary machines are more quiet, durable and less likely to break down.

The Boiler

The boiler is the component which heats the water to the ideal temperature to extract. The steam produced reaches the portafilter, which holds the espresso grounds. It is then pumped into the cup. In this process, the steam creates pressure to push through the coffee grounds. This results in a whipped-up the top of the espresso. This is one of the main characteristics of a good espresso maker barista.

There are three kinds of espresso makers, which differ in the type of pump they use and the degree of heat that the brew is. There are a variety of ways that the brew can be controlled, as well as the size of the cup that the machine is capable of making.

The first espresso machines were steam-type. They utilized only one boiler to make both steam and brew however, the pressure they could generate was low - only two bars of atmospheric pressure maximum. The coffee tasted bitter and burned. The modern espresso machine was created by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso maker is a semi-automatic device with an electric pump. These are the things people think of when they think of an best espresso machine maker. Semi-automatic machines require you to grind and tamp your beans yourself while the pump controls the flow of water and pressure. This is an excellent compromise between human control and mechanised reliability.

The Filter

Espresso machines typically use filters that separate the coffee grounds from the hot water. The filter is also an essential component of the temperature control system because it stops the machine from overheating.

It also aids in flavor as a filter allows for a longer bloom phase. This lets the beans release their flavors, and allows for a better extraction.

However it is crucial to keep in mind that even a good filter can result in a poor cup of coffee, since the quality of the beans and extraction are crucial.

This is where the magic happens, it's what makes an espresso really taste good. The grouphead, sometimes called the brewhead, is where the portafilter (the thing you put the ground coffee in) sits when you're making espresso.

Steam-driven espresso machines make use of hot water heated in an airtight vessel to create steam. The steam then moves hot water through the grounds of the coffee under pressure. These machines are cheaper and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect brewing conditions since they operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.

In recent times, espresso machines powered by compressed air-pump are becoming increasingly popular. They utilize an air compressor to force hot water through the ground and are much more mobile than electric steam-driven espresso machines.