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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. What exactly does it work?

To make an espresso coffee makers hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee, but the difference is in the pressure.

The Head of the Group

As the name suggests, the group head is the place you put your portafilter in when making espresso makers. It disperses the water into the portafilter, Machine espresso and regulates the pressure of extraction. There are numerous kinds of group heads each with distinct advantages and drawbacks. Some are focused on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. There are also some that include a mix of features, like the E61 one, which is to be the most popular among baristas because of its ability to provide multiple benefits in one package.

As you can see in the photo above the group head is fitted with several notches. The portafilter is placed into these notches and turn the head around to secure it. A rubber gasket is located within the notches to make a seal when you insert your portafilter. The notches allow for an exact placement of the portafilter. This is crucial for an even 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 cycling hot water through the brew basket, and around the portafilter, ensuring that it's always at the right temperature to extract. This is important because even a few degrees can be the difference between a good and excellent espresso.

The Pump

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

Pumps are generally less expensive than piston-driven machines and tend to last longer, but both types of machines can become damaged due to excessive use and poor cleaning. They also add mechanical complexity, Machine espresso which can result in the cost of even the simplest models.

Some espresso machines use steam pressure instead of a pump for brewing espresso. This can cause over-extraction because the boiler that makes steam also heats the water to boil. These machines also have to continually rebuild their pressure between cups. This requires energy and time.

A majority of espresso machines use a vibration or rotary pump, with a vibration model that uses a vibrating disc that generates the pressure, and rotating models that push hot water through the grounds at high speed. Both types of machine can make excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is what heats the water to a temperature that is ideal to extract. The steam that is produced will eventually reach the portafilter, which holds the espresso grounds. It is then funneled into the cup. The steam creates pressure and pushes through the coffee grounds. This creates a foam on the top of the espresso coffee maker. This is one of the main characteristics of a great espresso.

There are three different types of espresso machines, each with different types of pumps and the temperature of the brew. There are different ways in which the brew can be controlled, as well as the size of the cup the machine can make.

The first espresso machines were steam type. They used one boiler to create both steam and brew, however the pressure they were able to produce was not very high - two bars of atmospheric pressure at most. This led to the coffee tasting bitter and burnt. This is the reason why Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most popular espresso machine is a semiautomatic with an electric pump. These are the things people think of when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans on your own however the pump controls the flow of water and pressure. This is a great compromise between the human touch and the mechanized quality.

The Filter

Typically, espresso machines have filters that separate the grounds of the coffee as they go through the hot water. The filter is also an essential element of the machine's temperature control, since it helps to prevent overheating.

A filter can also help with flavor, as it permits an extended flowering time. This lets the beans release their flavor and allows for a better extraction.

However it is crucial to keep in mind that even a great filter can result in a poor cup of coffee as the quality of the beans and extraction is important.

It's in this area that the magic occurs. This is what makes espresso taste so delicious. The grouphead (also called the brewhead) is where you put the portafilter, the device which you put the coffee grounds into, when making espresso.

In a steam-driven espresso machine 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 owner to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect conditions for brewing, as they only operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.

In recent years, espresso machines driven by a compressed air compressor have become increasingly popular. They utilize an air compressor to force hot water through grounds, and are far more portable than steam-driven electric machines.