How Does Machine Espresso Work?

Machine espresso uses precision pressure and amazing filter technology to make the delicious coffee we enjoy. How exactly does it work?

professional espresso machine for home is created by forcing hot water under high pressure through finely-ground coffee. The process is similar to that of making drip coffee. However the pressure is the primary difference.

The Head of the Group

The name implies, the group head is the place you insert your portafilter when making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the extraction. There are a variety of group heads each with its own advantages and disadvantages. Some are specifically designed for stability of temperature while others are built to handle pre-infusion. Others are made to control the lever. Some contain a variety of features, like the E61 one, which is the most popular choice among baristas for its ability to provide multiple benefits in a single package.

As you can see in the photo above The group head features many notches in which you can place your portafilter and twist it manually to lock it in. There is also a rubber gasket that resides inside the notches and helps create an airtight seal after inserting your portafilter into the machine. The notches allow for precise placement of the portafilter. This is crucial for an efficient extraction.

In addition to allowing you easily connect your portafilter, the group head is also responsible to maintain an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket to ensure the temperature is always right for extraction. This is crucial, since even a few degrees can be the difference between a good and excellent espresso.

The Pump

Unlike 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 required to extract espresso. The pressure is built by pumping water through a heat exchanger and then through the ground coffee.

Pumps are typically less expensive than piston-driven models, and they tend to last longer, but both types of machines can become damaged due to excessive use and poor cleaning. Pumps are also more complicated mechanically, which can raise the cost of even the most basic models.

Some espresso machines remove the pump entirely and employ steam pressure to create espresso. The drawback of this is that the boiler that produces steam also increases the temperature of the water until it reaches boiling which could lead to over-extraction. They also have to continuously rebuild their pressure between cups. This takes energy and time.

Many compact espresso machine machines utilize an rotary or vibrating pump, which is a vibration model using a vibrating disc to create the pressure, and the rotary model pushing hot water through the grounds at high speed. Both machines can make great espresso but rotary machines are more stable, quieter and less likely to break.

The Boiler

The boiler is what heats the water to the right temperature to extract. The resultant steam then reaches the portafilter, which contains the ground espresso coffee and is then pumped into the cup. During this process the steam is able to create enough pressure to push the grounds of coffee through. This creates a crema on the top of the espresso. This is one of the main characteristics of a good espresso.

There are three distinct types of espresso machines, each with different pumps and brew temperature. There are different ways to control the amount of brew, as well as the size of cup that can be produced by the machine.

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

The most well-known espresso maker is a semi-automatic one that has an electric pump. When people think of espresso machines, they picture these machines. If you have a semi-automatic machine you grind the beans and then tamp them by hand, but the pump provides regulated water flow and pressure. This is an excellent compromise between human touch and the mechanised accuracy.

The Filter

Typically, espresso machines employ filters to separate the coffee grounds as they pass through the hot water. The filter is also an essential element of the machine's temperature control, as it prevents overheating.

It also enhances flavor as a filter allows for a more prolonged bloom time. This lets the beans release their nuances, 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 process, are still very important.

This is where the magic happens, it's what makes an espresso really taste great. The grouphead (also called the brewhead) is where you put the portafilter, the device used to place the coffee grounds into, when making italian espresso machines.

Steam-driven espresso machines use hot water that is heated in an airtight vessel to create steam. The steam then pushes hot water through grounds of the coffee under pressure. These machines are cheaper and easier for the user 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 ideal 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 much more mobile than electric steam-driven espresso machines.