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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and amazing filter technology to make the coffee we love. What exactly is it that makes it work?

Espresso is created by forcing hot water under high 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

The name implies, the group head is the place you place your portafilter while making espresso. It disperses water in the portafilter and regulates the pressure during the extraction. There are numerous kinds of group heads each with its own advantages and drawbacks. Some are designed to provide stability of temperature while others are built to handle pre-infusion. Others are made to control the lever. Some are a combination, such as the E61. This is a very popular choice for baristas as it provides a variety of benefits in one package.

As you can see from the image above the group head is fitted with several notches. You can place your portafilter in these notches and then twist the head to lock it. There is also a gasket made from rubber that resides inside the notches and helps to 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 vital for an even extraction.

Aside from allowing you to easily insert your portafilter, the group head is responsible to ensure that the temperature remains even. This is done by cycling hot water around the portafilter, and through the brew-basket to ensure that the temperature is at the right level to extract the coffee. This is important because even a few degrees can make the difference between a excellent and great espresso.

The Pump

The motorized pumps that are used in best espresso machine under 200 machines that rotate provide the nine atmospheric bar pressure needed to extract espresso. This differs from manual piston machines which use levers. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are generally less expensive and last for longer than piston-driven machines. However, both kinds of machines can degrade due to excessive use and inadequate cleaning. They also make mechanically complex and can lead to a high price tag on even the most basic models.

Some espresso machines make use of steam pressure instead of a pump to brew espresso. This can cause over-extraction because the boiler that makes steam also heats the water to boil. The machines must also constantly rebuild their pressure in between cups. This takes energy and time.

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

The Boiler

The boiler is what is used to heat the water to the ideal temperature for extraction. The resulting steam reaches the portafilter, which contains the ground espresso coffee, and is then pumped into the cup. During this process, steam causes pressure to push through the grounds of the coffee. This creates a foam on the top of the espresso machine coffee. This is the hallmark of a good espresso.

There are three distinct types of espresso machines, each with a different type of pump and brew temperature. There are various ways to control the strength of the brew and the size of cup that can be produced by the machine.

The earliest buy espresso machine machines were steam types. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burnt. The modern espresso machine was designed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp the beans yourself while the pump controls the flow of water and pressure. This is a fantastic compromise between human control and mechanised accuracy.

The Filter

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

It also improves flavor as a filter can allow for a longer bloom time. This allows the beans to release their flavors, and also allows for better extraction.

It is important to keep in mind that even the finest filter can make a bad cup of coffee. The quality of the beans, and the extraction, are still very important.

This is where the magic happens, and it's what makes espresso taste good. The grouphead, sometimes called the brewhead, is where the portafilter (the thing you put the coffee ground into) is placed when you're 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 at a 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 produce the perfect brewing conditions since they are only operating 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 become more popular. They use an air compressor to force hot water through the ground and are more mobile than steam-driven electric espresso machines.