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How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to create the perfect cup of coffee. How exactly does it work?

To make espresso, 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 Group Head

The group head is the portafilter that is inserted when you are making espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure of the resulting extraction. There are numerous kinds of group heads each with its own advantages and drawbacks. Some are designed for the stability of temperature while some are built to handle pre-infusion. Others are made to control the lever. Some have a combination, such as 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 photo the group head has a number of notches. It is possible to place your portafilter in these notches and then turn the head around to secure it. There is also a gasket made from rubber that is a part of the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches permit precise placement of your portafilter. This is vital for an even extraction.

In addition to allowing you to effortlessly insert your portafilter the group head is also responsible for maintaining a consistent temperature. It does this by circulating hot water through the brew basket, and around the portafilter, making sure that it is always at the right temperature for extraction. It is important to remember that even a slight deviation can make the difference between a good and a great espresso.

The Pump

Unlike manual piston machines, which rely on a lever that pressurize water, rotary espresso machine with grinder machines rely on motorized pumps to provide the nine atmospheric bars of pressure that are required for espresso extraction. The pressure builds by drawing tap water from a reservoir and pumping it through a heat exchanger prior being pumped through the ground coffee inside the group head.

Pumps tend to be cheaper than piston-driven machines and tend to last longer. However, both types of machine can degrade with overuse and insufficient cleaning. Pumps are also more complicated mechanically, which can raise the price of even the simpler models.

Some espresso machines make use of steam pressure instead of a pump for brewing espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of water to the point of boiling and can result in excessive extraction. The machines also need to constantly rebuild their pressure between cups. This takes energy and time.

Many espresso machines employ an rotary or vibrating pump, with a vibration model using a rotating disc to create pressure, and an rotary model that pushes hot water through the grounds at high speed. Both models can make a great espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is what makes the water warm to the right temperature to extract. The steam that is produced reaches the portafilter which holds the ground espresso coffee and is then pumped down into the cup. During this process the steam is able to create enough pressure to push the grounds of coffee through. This creates a foam on top espresso machines of the espresso. This is the hallmark of a great espresso.

There are three kinds of espresso makers. They 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 may be controlled, as well as the size of the cup that the maker can create.

The first espresso machines were steam-type. The first espresso machines were steam types. This resulted in the coffee tasting burnt and bitter. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most popular espresso maker is a semi-automatic one that has an electric espresso maker pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp your beans yourself, but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and mechanized consistency.

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 element of the machine's temperature control, as it prevents overheating.

A filter also improves flavor as it allows for a longer flowering period. This lets the beans release their flavor and allows for a better extraction.

It is important to keep in mind that even the best filter can result in a bad cup of coffee. The quality of the beans, and the extraction, remain vital.

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

In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. Steam then pushes the hot water through the grounds at high pressure. These types of machines are usually less expensive and easier to maintain than pumps-driven models. However, they are limited in their ability to produce the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.

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