How Does Machine Espresso Work?

Machine espresso employs precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. How exactly does it work?

commercial espresso machine is made by forcing hot water under pressure through finely ground coffee. The process is similar to making drip coffee, but the major difference is in the pressure.

The Head of the Group

The name implies, the group head is where you insert your portafilter when making espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure that results from the extraction. There are several different types of group head, each with their own advantages and drawbacks. Some focus on temperature stability, others on pre-infusion options, and others are designed to control the lever. Some are a combination, such as the E61. This is a favorite among baristas as it provides a variety of advantages in a single package.

As you can see in the above photo the group head comes with numerous notches that you can place your portafilter and then twist it with your hands to lock it in. There is also a gasket made of rubber that is a part of the notches and helps to create a seal when you insert your portafilter into the machine. The notches allow for an exact placement of the portafilter. This is crucial to ensure an even extraction.

The group head not only allows you to place your portafilter easily but also maintains an even temperature. This is done by cycling hot water around the portafilter and through the brew-basket, ensuring the temperature is always right for extraction. It is important to note that even a tiny variation can mean the difference between a good and excellent espresso.

The Pump

The motorized pumps that are used in espresso machines that rotate provide the nine atmospheric bar pressure that is required to extract espresso. This is different from manual piston machines that use a lever. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior to it is shot through the ground coffee in the group head.

Pumps tend to be cheaper than piston-driven machines and tend to last longer, however both types of machine can be damaged by excessive use and inadequate cleaning. They also add mechanical complexity and can lead to a high price tag on even the most basic models.

Certain espresso machines utilize steam pressure instead of a pump in order to brew espresso. The drawback of this is that the same boiler that produces steam also raises the temperature of the water to boiling which could lead to over-extraction. The machines must also continuously rebuild their pressure between cups. This requires energy and time.

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

The Boiler

The boiler is the component which heats the water to the ideal temperature for extraction. The steam created reaches the portafilter, which is a container for espresso grounds. The steam is then channeled into the cup. During this process the steam causes enough pressure to push the grounds of the coffee through. This results in a layer of crema that is then poured over. This is one of the hallmarks of a good espresso.

There are three types of espresso machines, Machine Espresso each with different types of pumps and brew temperature. There are a variety of ways to control the strength of the brew and the size of the cup that can be made by the machine.

The first espresso machines were steam-type. The first espresso machines were steam types. The coffee tasted bitter and burnt. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most popular espresso machine is a semiautomatic with an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic espresso machine, you need to grind the beans and then tamp them by hand, but the pump provides regulated water flow and pressure. This is a great solution that combines human control with mechanized accuracy.

The Filter

Typically, espresso machines have filters that separate the coffee grounds as they pass through the hot water. The filter is also a crucial part of the temperature control system because it stops the machine from overheating.

A filter can also help with flavor, as it permits an extended flowering time. This lets the beans release their nuances, and allows for a better extraction.

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

It's here that the magic takes place. This is the reason why espresso tastes so good. The grouphead, sometimes referred to as the brewhead, is where the portafilter (the thingy you put the coffee grounds into) is placed when making espresso.

In an espresso machine that is driven by steam, hot water is heated in an airtight container to create steam, which then pushes the hot water through the grounds at a high 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 ideal conditions for brewing, as they 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 are becoming increasingly popular. They make use of an air compressor to force hot water through the ground, and are more mobile than electric steam-driven espresso machines.