How Does Machine Espresso Work?

Machine espresso employs precise pressure and mind-blowing filter technology to create the coffee we love. What exactly is it?

To make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However the pressure is the major difference.

The Head of the Group

As the name implies the group head is the place you put your portafilter in when brewing espresso. It is responsible for dispersing water into the portafilter, and controlling the pressure of the resulting extraction. There are many different types of group heads, each with its own advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion capabilities, and still others are designed to control the lever. There are some that include a mix 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 image above the group head is made up of several notches to place your portafilter and then twist it by hand to secure it. A gasket of rubber is situated within the notches to create a seal as you insert your portafilter. The notches allow for the precise placement of the portafilter. This is essential for a consistent extraction.

The group head does not just allow you to insert your portafilter easily, but it also maintains a constant 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 important, as even a small difference in temperature can be the difference between a excellent and great espresso.

The Pump

Unlike manual piston machines, that use a lever to pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure needed for espresso extraction. This pressure builds up 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 cheaper than piston-driven machines espresso machines and tend to last longer. However, both types of machines may be damaged by excessive use and inadequate cleaning. Pumps are also more complicated mechanically, which can raise the price of even the simplest models.

Some espresso machines make use of steam pressure instead of a pump in order to brew espresso. This can result in over-extraction because the boiler that produces steam also heats the water until it comes to a boil. They also have to continuously rebuild their pressure between cups. This takes energy and time.

A large majority of espresso machines employ a rotary or vibration pump. A vibration model uses an oscillating disk to create pressure, while a Rotary model pushes hot coffee through the ground at a rapid speed. Both machines can make excellent espresso however rotary machines tend to be more stable, quieter and less likely to break down.

The Boiler

The boiler is the part that heats water to the optimal temperature to extract. The steam created will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. It is then pumped into the cup. During this process the steam creates enough pressure to push the grounds of the coffee through. This creates a foam on top of the espresso. This is one of the main characteristics of a good espresso.

There are three kinds of discount espresso machines makers, and they differ in the type of pump they employ and how hot the coffee is. There are various ways that the brew may be controlled as well as the size of the cup the machine is capable of making.

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

The most common espresso maker is a semi-automatic one with an electric pump. This is what people envision when they think of an espresso machine. Semi-automatic machines require you to grind and tamp the beans by yourself while the pump controls the water flow and pressure. This is an excellent compromise between human touch and mechanized consistency.

The Filter

Espresso machines usually use a filter that separates the grounds of coffee from hot water. The filter is also a vital component of the machine's temp control, as it helps prevent overheating.

It also enhances flavor, as it allows for a longer bloom time. This helps the beans release their nuances and gives an opportunity to improve extraction.

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

It's in this area that the magic takes place. This is what makes espresso taste so delicious. The grouphead (also known as the brewhead) is where you place the portafilter, the device that you use to put the coffee grounds in, when making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to make steam. The steam then pushes hot water into the coffee grounds under high pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. However, they are limited in their capacity to create the ideal brewing conditions, as they only operate at 1-1.5 bars of pressure. 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 into the grounds and are significantly more portable than steam-driven electric machines.