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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly is it that makes it work?

espresso machine uk is produced by pushing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the primary difference.

The Group Head

The group head is the portafilter you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter, and controlling the pressure of the extraction. There are many different kinds of group heads, each with their particular advantages and disadvantages. Some are specifically designed for the stability of temperature while some are designed to handle pre-infusion. Some are designed to control the lever. Some contain a variety of features, such as the E61, which is the most popular choice among baristas due to its ability to offer multiple perks in one package.

As you can see in the above image, the group head has several notches where you place your portafilter before twisting it with your hands to lock it in. A gasket of rubber is situated inside the notches, which helps create a seal as you insert your portafilter. The notches on the head permit a precise positioning of the portafilter which is necessary to ensure an efficient extraction.

In addition to allowing you to effortlessly insert your portafilter the group head is responsible to maintain an even temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is constant to extract the coffee. It is important to note that even a few degree difference can make the difference between a good and a great espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure required to extract espresso. This pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger prior to being pumped through the ground coffee in the group head.

Pumps are generally less expensive than piston-driven machines, and they tend to last longer, however both types of machines could get damaged through overuse and lack of cleaning. They also increase the complexity of mechanical systems and can lead to an expensive price for even the simplest models.

Certain espresso machines utilize steam pressure instead of a pump for brewing espresso. This can cause over-extraction because the boiler that makes steam also heats the water until it comes to a boil. The machines must also constantly rebuild their pressure between cups. This takes energy and time.

Many espresso machines use an rotary or a vibration pump. A vibration model utilizes a rotating disk to generate pressure, whereas the Rotary model pushes hot coffee through the ground at high speed. Both machines can make great espresso however rotary machines tend to be quieter, more durable and less likely to break.

The Boiler

The boiler makes the water warm to a temperature that is ideal for extraction. The steam created reaches the portafilter, which is a container for espresso grounds. The steam is then channeled into the cup. In this process, the steam causes pressure to push through the coffee grounds. This results in a layer crema that is then poured over. This is a sign of a good cheap espresso machine.

There are three kinds of espresso makers, and they differ in the type of pump they use and how hot the espresso is. There are different ways in which the brew can be controlled as well as the size of the cup the machine can make.

The first espresso machines were steam-types. They had one boiler to make both steam and brew however, the pressure they could produce was not very high - two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. This is the reason Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most common espresso machine is a semiautomatic with an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic espresso machine machines require you to grind and tamp the beans yourself The pump, however, regulates the water flow and pressure. This is an excellent compromise between human touch and mechanized quality.

The Filter

Espresso machines usually use a filter that separates the coffee grounds from the hot water. The filter is also a vital element of the machine's temperature control, as it prevents overheating.

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

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

It's here that the magic happens. This is what makes espresso taste so good. The grouphead, often called the brew head, is the place where the portafilter (the thing you put the coffee ground into) is placed when making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to make steam. The steam then pushes hot water through the grounds of the coffee under pressure. These kinds of machines are usually less expensive and easier to maintain than pump-driven models. They are however limited in their ability to create the ideal 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 machines powered by compressed air-pump have become increasingly popular. They use an air-compressor to push hot water through the ground, and are more mobile than electric steam-driven espresso machines.