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How Does Machine Espresso Work?

The machine espresso makes use of precision pressure, and a filtering technology that is amazing to create the coffee you enjoy. What exactly is it?

In order to make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the major difference.

The Head of the Group

As the name implies, the group head is where you place your portafilter while brewing espresso coffee maker. It is responsible for dispersing the water into the portafilter and controlling the pressure of the resulting extraction. There are a variety of group heads, each with its own advantages and disadvantages. Some are specifically designed for stability in temperature, while others are designed to handle pre-infusion. Others are built to control the lever. There are some that have a combination of features, like the E61, which is considered to be the most popular among baristas for its ability to offer multiple perks in a single package.

As you can see in the photo above the group head comes with several notches where you place your portafilter before twisting it by hand to lock it in. There is also a gasket made of rubber which is located inside the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches on the head allow for a precise location of the portafilter which is necessary to ensure an even extraction.

The group head does not just allow you to insert your portafilter easily however, it also keeps a constant temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket, making sure that the temperature is always at the right level to extract the coffee. It is important to realize that even a slight deviation can make the difference between a great and a great espresso machines home.

The Pump

The motorized pumps used in rotary espresso machines provide the nine atmospheric bar pressure required to extract espresso. This differs from manual piston machines that use a lever. This pressure is generated by pumping water through a heat exchanger and then through the ground coffee.

Pumps are typically cheaper and last longer than piston-driven machines. However, both types of machines can degrade because of excessive use and insufficient cleaning. They also add mechanical complexity and can lead to an expensive price for even the most basic models.

Some espresso machines make use of steam pressure instead of a pump for brewing espresso. This can cause over-extraction because the boiler that produces steam also causes the water to boil. In addition these machines typically have to rebuild their pressure between cups, which takes time and energy.

Many espresso machines make use of either a vibration or rotary pump. A vibration model uses an oscillating disk to create pressure, while a rotary model pushes hot water through the ground at a fast speed. Both machines produce great espresso, but rotary machines are more quiet, durable and less likely to fail.

The Boiler

The boiler is the one that will heat the water to the perfect temperature to extract. The steam produced is then directed to the portafilter, which contains the espresso coffee grounds. The steam is then channeled into the cup. During this process, steam causes pressure to push through the coffee grounds. This results in a layer of crema on top. This is a sign of a good espresso.

There are three types of espresso makers (their website). They differ in the type of pump they employ and how hot the espresso is. There are different ways that the brew may be controlled as well as the dimensions of the cup the machine can produce.

The first espresso machines were steam-types. They used a single boiler to make both steam and brew, however the pressure they were able to create was minimal - two bars of atmospheric pressure at most. This resulted in the coffee tasting burnt and bitter. This is the reason Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso coffee machine machine.

The most common espresso maker is a semi-automatic device that has an electric pump. This is what people envision when they imagine an espresso machine. If you have a semi-automatic machine you grind the beans and then tamp them by hand. The pump controls the flow of water and pressure. This is a great compromise between human control and mechanised accuracy.

The Filter

Typically, espresso machines employ filters to separate the grounds of the coffee as they go through the hot water. The filter is also a crucial part of the temperature control system, as it keeps 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 flavor and allows for a better extraction.

However, it is important to remember that even a top filter can make a terrible cup of coffee as the quality of the beans and extraction are important.

This is where the magic happens, it's the thing that makes espresso taste good. The grouphead (also known as the brewhead) is where you place the portafilter, the device which you put the coffee grounds in, when making espresso.

In a steam-driven espresso machine hot water is heated in an airtight tank to create steam. Steam is then pushed through the grounds at a high pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing since they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

In recent years, espresso coffee machines for sale machines driven by a compressed air pump have become increasingly popular. They utilize an air compressor to push hot water across the ground and are more mobile than steam-driven electric espresso maker espresso machines.