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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the delicious coffee for espresso machine we enjoy. What exactly is it that makes it work?

Espresso is created by forcing hot water under pressure through finely ground coffee. The process is similar to making drip coffee but the difference is in the pressure.

The Head of the Group

The name implies the group head is where you put your portafilter in when brewing espresso. It disperses water in the portafilter, and then regulates the pressure during the extraction. There are a variety of group heads each with their own advantages and disadvantages. Some are focused on temperature stability, while others on pre-infusion capabilities, and still others are designed to control the lever. There are even some that contain a variety of features, such as the E61 that is the classic choice among many baristas due to its ability to offer multiple benefits in a single package.

As you can see in the picture above the group head has a number of notches. You place your portafilter into these notches and twist the head to secure it. There is also a rubber gasket in the notches and helps create a seal when you insert your portafilter into the machine. The notches on the head permit an exact location of the portafilter which is crucial to ensure an efficient extraction.

The group head is not just able to allow you to insert your portafilter easily however, it also keeps an even temperature. It does this by circulating hot water through the brew pan and around the portafilter, ensuring that it's always at the correct temperature to extract. This is vital, because even a few degrees can mean the difference between good and great espresso.

The Pump

Unlike manual piston machines, that use a lever to pressurize water, rotating espresso machines rely upon motorized pumps that provide the nine atmospheric bars of pressure necessary for espresso extraction. The pressure builds by drawing tap water from a reservoir and pumping it through a heat exchanger prior to it is shot through the ground coffee inside the group head.

Pumps are generally less expensive and last longer than piston-driven machines. However, both types of machines are susceptible to degrading due to excessive use and poor cleaning. They also add mechanical complexity and can lead to a high price tag on even the simplest models.

Certain espresso machines do away with the pump completely and instead use steam pressure to brew espresso. The drawback of this is that the boiler that produces steam also increases the temperature of the water to boiling which can cause excessive extraction. These machines also have to continuously rebuild their pressure between cups. This requires energy and time.

Many espresso machines employ an rotary or vibrating pump, which is a vibration model that uses a vibrating disc to generate the pressure and a rotary model pushing hot water through the grounds under high speed. Both types of machines can make a great espresso, however rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler will heat the water to the ideal temperature for extraction. The resulting steam reaches the portafilter that contains the ground espresso and is then pumped into the cup. During this process, the steam creates pressure to push through the grounds of the coffee. This creates a layer crema on top. This is one of the main characteristics of a great espresso.

There are three types of espresso makers, which differ in the kind of pump they use and the degree of heat that the coffee is. There are a variety of ways in which the brew can be controlled as well as the dimensions of the cup the machine can make.

The first espresso machines were steam-based. The first espresso machines were steam types. The coffee tasted bitter and burned. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most commonly used espresso maker is a semi-automatic machine that has an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic machine you must grind the beans and then tamp them by hand. The pump is able to regulate the flow of water and pressure. This is an excellent compromise between human touch and the mechanised quality.

The Filter

Espresso machines typically have filters that separate the grounds of the coffee from hot water. The filter is also an important component of the temperature control system, as it prevents the machine from overheating.

It also aids in flavor, since a filter allows for a more prolonged bloom time. This lets the beans release their flavor and allows for a better extraction.

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

This is where the magic happens. It's what makes espresso taste good. The grouphead, also called the brew head, is where the portafilter (the thing you put the ground coffee into) sits when you're making espresso machines home.

Steam-driven espresso machines make use of hot water that is heated inside an airtight container to create steam. The steam then moves hot water through the grounds of coffee at high pressure. These machines are less expensive and easier for the owner to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent years, compressed air-pump-driven espresso machines have become more popular. They use an air compressor to force hot water into the ground and are more mobile than electric steam-driven best small espresso machine machines.