How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the delicious coffee we enjoy. How exactly does it work?

To make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.

The Head of the Group

The group head is the portafilter that you insert when brewing espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the resulting extraction. There are a variety of types of group heads each with its own advantages and disadvantages. Some are specifically designed for stability of temperature while others are designed to handle pre-infusion. Some are designed to control the lever. There are also some that contain a variety of features, such as the E61 one, which is the classic choice among many baristas for its ability to offer multiple perks in one package.

As you can see in the above photo, the group head has several notches where you put your portafilter, then twist it manually to lock it in. There is also a gasket of rubber that is a part of the notches and helps to create the seal when you insert your portafilter into the machine. The notches on the head permit an exact positioning of the portafilter which is necessary for a consistent extraction.

In addition to allowing you to effortlessly insert your portafilter the group head is also responsible to maintain an even temperature. It does this by cycling hot water through the brew container and around the portafilter, ensuring that it is always at the right temperature to extract. This is vital, because even a small difference in temperature can make the difference between good and excellent espresso.

The Pump

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

Pumps are typically less expensive and last for longer than piston-driven machines. However, both kinds of machines may degrade because of excessive use and poor cleaning. Pumps are also more complex mechanically, and can add to prices of even simplest models.

Some espresso machines do away with the pump completely and utilize steam pressure to make espresso. This could lead to over-extraction since the boiler that makes steam also heats the water to boil. They also have to continually rebuild their pressure between cups. This takes energy and time.

Many espresso machines make use of an rotary or vibrating pump, which has a vibration model that uses a vibrating disc to create the pressure and the rotary model pushing hot water through the grounds under high speed. Both machines can make excellent espresso however rotary machines tend to be more quiet, durable and less likely to fail.

The Boiler

The boiler is the component that heats water to an optimal temperature for extraction. The steam produced is then directed to the portafilter, which holds the espresso grounds. It is then pumped into the cup. In this process, the steam creates pressure and pushes through the grounds of the coffee. This produces a layer of crema that is then poured over. This is a hallmark of a good espresso.

There are three different types of espresso machines, each having a different type of pump and the temperature of the brew. There are a variety of ways that the brew can be controlled, as well as the size of the cup that the maker can create.

The first retro espresso machine machines were steam-type. The first espresso machines were steam types. This led to the coffee tasting burnt and bitter. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker is a semiautomatic machine that has an electric pump. These are what people imagine when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans yourself while the pump controls the flow of water and pressure. This is a fantastic compromise between human control and mechanised accuracy.

The Filter

Typically, espresso machines employ a filter to separate out the grounds of the coffee as they go through the hot water. The filter is also an essential component of the temperature control system, because it stops the machine from overheating.

It also aids in flavor, since a filter can allow for Machine Espresso a longer bloom time. This helps the beans release their flavor and gives an opportunity for better extraction.

It is important to remember that even the finest filter can make a bad cup of coffee. The quality of the beans and the extraction process, remain crucial.

This is where the magic happens, it's what makes an espresso really taste great. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy which you put the coffee grounds in, when making espresso.

In the steam-driven espresso machine hot water is heated in an airtight container to produce steam, which is then pushed through the grounds with high pressure. These kinds of machines are generally less expensive and easier to maintain than pump-driven models. However, they are not as efficient in their ability to create the perfect brewing conditions 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 become more popular. They use an air-compressor to push hot water through the ground and are much more mobile than electric steam-driven espresso machines.