How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and amazing filter technology to make the perfect cup of coffee. But how exactly does it work?

To make an espresso hot water is pushed under pressure through finely ground coffee and espresso maker. The process is similar to making drip coffee. However the pressure is the main difference.

The Group Head

The group head is the portafilter that you place in the espresso maker when making it. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the resulting extraction. There are various kinds of group head each with its distinct advantages and disadvantages. Some focus on temperature stability, some on pre-infusion options, and others are designed to control the lever. There are some that contain a variety of features, like the E61 one, which is the standard choice for many baristas due to its ability to offer multiple benefits in a single package.

As you can see from the picture above the head of the group is equipped with several notches. The portafilter is placed in these notches and then twist the head to secure it. A gasket made of rubber is placed in the notches to make a seal when you insert your portafilter. The notches on the head allow for a precise location of the portafilter which is necessary for an efficient extraction.

The group head is not just able to allow you to place your portafilter easily however it also keeps the same temperature. It does this by circulating hot water through the brew container and around the portafilter to ensure that it is always at the right temperature to extract. It is crucial to keep in mind that even a few degree difference can make the difference between a decent and a great espresso coffee machines.

The Pump

In contrast to manual piston machines which use a lever to pressurize water, rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure necessary for espresso extraction. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior to being shot through the ground coffee inside the group head.

Pumps tend to be less expensive than piston-driven machines, and tend to last longer, however both types of machines could become damaged due to excessive use and poor cleaning. They also make mechanically complex, which can result in an expensive price for even the simplest models.

Some espresso machines remove the pump completely and use steam pressure to brew espresso. The disadvantage of this is that the same boiler that produces steam also increases the temperature of the water to the point of boiling and can result in over-extraction. In addition the machines often have to restore their pressure between cups, which requires time and energy.

Many espresso machines use an rotary or a vibration pump. A vibration model uses the vibrating disk to create pressure, whereas a rotating model pushes hot water through the ground at a fast speed. Both types of machine can make a great espresso, however rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is what is used to heat the water to the ideal temperature for extraction. The steam produced gets to the portafilter which is the container that holds the espresso coffee grounds. It is then poured into the cup. The steam creates enough pressure to push the grounds of the coffee through. This results in a layer crema that is then poured over. This is one of the main characteristics of a good espresso.

There are three types of espresso makers, which differ in the type of pump they use and the degree of heat that the coffee is. There are a variety of ways in which the brew could be controlled and the size of the cup that the maker can create.

The first espresso machines were steam-type. They utilized one boiler to create steam and brew, but the pressure they could generate was low - only two bars of atmospheric pressure, at most. The coffee tasted bitter and burned. This is the reason Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most common espresso maker is a semi-automatic machine that has an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans on your own, but the pump regulates the water flow and pressure. This is an excellent compromise between human touch and mechanized consistency.

The Filter

Espresso machines usually have a filter that separates the grounds of the coffee from the 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, as it allows for a more prolonged bloom time. This helps the beans to let their nuances out and provides the chance for better extraction.

However it is crucial to keep in mind that even a good filter can produce a bad cup of coffee, since the quality of the beans and extraction is vital.

It's here that the magic happens. This is what makes espresso taste so good. The grouphead, also called the brewhead, is where the portafilter (the thingy you put the ground coffee into) sits when you're making espresso.

In a steam-driven espresso machine hot water is heated in an airtight tank to create steam. Steam then pushes the hot water through the grounds at a high pressure. These types of machines are typically cheaper and easier to maintain than pump-driven models. However, espresso makers they are limited in their ability to produce the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.

In recent years, espresso machines powered by a compressed air pump have become increasingly popular. They use an air compressor to push hot water through the ground. They are also more mobile than electric steam-driven espresso machines.