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How Does Machine Espresso Work?

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

In order to make espresso 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 Group Head

The name implies, the group head is the place you insert your portafilter when brewing espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the extraction. There are a variety of types of group head, each with their particular advantages and drawbacks. Some are specifically designed for stability in temperature, while others are specifically designed 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 one package.

As you can see in the image above the group head is fitted with several notches. It is possible to place your portafilter in these notches, then twist the head to lock it. There is also a gasket of rubber which is located inside the notches and helps create a seal when you insert your portafilter into the machine. The notches on the head allow for a precise position of the portafilter which is essential to ensure an even extraction.

In addition to allowing you to easily insert your portafilter, the group head is responsible to maintain an even temperature. It does this by cycling hot water through the brew pan and around the portafilter, making sure that it is always at the right temperature to extract. This is crucial, since just a few degrees could be the difference between a good and great espresso.

The Pump

Contrary to manual piston machines which rely on a lever to pressurize water, the rotary espresso machines use motorized pumps to provide the nine atmospheric bars of pressure required to extract espresso. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be less expensive and last longer than piston-driven machines. However, both types of machines can deteriorate due to excessive use and inadequate cleaning. They also make mechanically complex which can result in the cost of even the most basic models.

Some espresso machines eliminate the pump completely and instead utilize steam pressure to make espresso. The drawback of this is that the same boiler that produces steam also increases the temperature of the water to the point of boiling which can cause excessive extraction. In addition these machines typically have to rebuild their pressure between cups, which requires time and energy.

A large majority of espresso machines employ an rotary or a vibration pump. A vibration model makes use of a vibrating disk to generate pressure, while a rotating model pushes hot water through the ground at a high speed. Both machines produce great cheap espresso machine, however rotary machines are quieter, more durable and less likely to break down.

The Boiler

The boiler is the one that makes the water warm to the ideal temperature for extraction. The steam that is produced reaches the portafilter, which contains the ground espresso coffee, and is then pumped into the cup. The steam creates enough pressure to push the grounds of coffee through. This produces a layer of crema that is then poured over. This is a sign of a great espresso.

There are three different types of espresso machines, each with a different type of pump and brew temperature. There are various ways that the brew may be controlled as well as the dimensions of the cup the maker can create.

The first buy espresso machines machines were steam types. They employed one boiler to make steam and brew, but the pressure they could create was minimal - two bars of atmospheric pressure at the most. This resulted in the coffee tasting bitter and burnt. This is why Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most commonly used italian espresso machine machine is a semiautomatic one with an electric pump. When people think of espresso makers machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans on your own while the pump controls the water flow and pressure. This is an excellent compromise between human control and mechanized consistency.

The Filter

Espresso machines typically have a filter that separates the grounds of the coffee from the hot water. The filter is also a vital element of the temperature control system, because it stops the machine from overheating.

A filter also helps with flavor, as it permits the beans to flower for a longer period of time. This allows the beans to release their nuances, and allows for better extraction.

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

It's here that the magic occurs. This is what makes espresso taste so good. The grouphead (also called the brewhead) is where you place the portafilter, the thingy used to place the grounds of your coffee into when making espresso.

Steam-driven espresso machines make use of hot water that is heated inside an airtight container to produce steam. The steam then moves hot water through the grounds of coffee at high pressure. These types of machines are usually less expensive and easier to maintain than pump-driven models. However, they are limited in their ability to produce the ideal conditions for brewing 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 become more popular. They utilize an air compressor to force hot water into the grounds and are significantly more portable than steam-driven electric machines.