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How Does Machine Espresso Work?

Machine espresso home machine makes use of precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. But how exactly does it work?

To make an espresso hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However, it is the pressure that makes the main difference.

The Head of the Group

As the name implies the group head is the place you place your portafilter when making espresso. It distributes water into the portafilter, and then regulates the pressure of extraction. There are numerous kinds of group heads, each with its own advantages and disadvantages. Some are designed to provide stability in temperature, while others are designed to handle pre-infusion. Some are designed to control the lever. Some come with a range of features, like the E61 that is to be the most popular among baristas due to its capacity to offer multiple benefits in one package.

As you can see in the image above the group head is made up of many notches in which you can place your portafilter and then twist it with your hands to lock it in. There is also a gasket of rubber which is located inside the notches, which helps create the seal when you insert your portafilter into the machine. The notches on the head permit a precise positioning of the portafilter which is crucial for an efficient extraction.

In addition to allowing you easily connect your portafilter, the group head is responsible for maintaining a consistent temperature. It does this by cycling hot water through the brew basket, and around the portafilter, ensuring that it is always at the right temperature to extract. It is important to note that even a few degree differences can make the distinction between a decent and a great espresso.

The Pump

Contrary to manual piston machines which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure needed for espresso extraction. This pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger prior to being shot through the ground coffee in the group head.

Pumps are generally less expensive and last longer than piston-driven machines. However, both types of machines can deteriorate because of excessive use and insufficient cleaning. They also make mechanically complex that can lead to an expensive price for even the simplest models.

Certain espresso machines utilize steam pressure instead of a pump to make espresso. This could lead to over-extraction since the boiler that makes steam also heats the water to boil. In addition these machines are often required to restore their pressure between cups, which takes time and energy.

A large majority of espresso machines employ the rotary or vibration pump. A vibration model employs the vibrating disk to create pressure, whereas the circular model pushes hot liquid through the ground at a rapid speed. Both machines can produce excellent espresso however rotary machines tend to be more quiet, durable and less likely to fail.

The Boiler

The boiler is the element that heats the water to the ideal temperature to extract. The resulting steam is then transferred to the portafilter, which contains the ground espresso and gets funnelled down into the cup. During this process the steam generates enough pressure to push the grounds of the coffee through. This creates a crema on top of the espresso. This is a hallmark of a good retro espresso maker (visit the following page).

There are three kinds of espresso makers, which differ in the kind of pump they use and how hot the coffee is. There are also different ways that the brew may be controlled as well as the size of the cup the maker can create.

The first commercial espresso machine machines were steam-type. They had one boiler to make steam and brew, but the pressure they could produce was very low - just two bars of atmospheric pressure, at most. This resulted in the coffee tasting bitter and burnt. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most well-known espresso maker is a semi-automatic device that has an electric pump. These are the images people have when they think of an espresso machine. Semi-automatic machines require you to grind and tamp your beans yourself however the pump controls the water flow and pressure. This is a great compromise between human control and mechanised accuracy.

The Filter

Typically, espresso machines employ filters that separate the grounds of coffee when they pass through the hot water. The filter is also a vital component of the machine's temperature control, as it helps prevent overheating.

It also improves flavor, as it lets you enjoy a longer bloom phase. This lets the beans let their nuances out, and also allows for better extraction.

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

This is where the magic happens, and it's what makes an espresso coffee machine uk really taste great. The grouphead, often called the brew head, is the place where the portafilter (the thingy you put the ground coffee into) is located when you're making espresso.

In an espresso machine that is driven by steam, hot water is heated in an airtight container to create steam, which then pushes the hot water through the grounds with high pressure. These machines are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect conditions for brewing, because they operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.

In recent years, compressed-air-pump-driven espresso machines have been gaining popularity. They use an air-compressor to push hot water through the ground and are more mobile than electric steam-driven espresso machines.