How Does Machine Espresso Work?

Machine espresso employs precise pressure and incredible filter technology to produce the delicious coffee we enjoy. But 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. However, the pressure is the primary difference.

The Group Head

As the name implies the group head is the place you place your portafilter while brewing espresso. It is responsible for Machine Espresso dispersing the water into the portafilter and controlling the pressure of the resulting extraction. There are several different types of group heads each with its unique advantages and drawbacks. Some are designed to provide stability in temperature, while others are built to handle pre-infusion. Others are made to control the lever. There are also some that include a mix of features, like the E61, which is considered the most popular choice among baristas for its ability to provide multiple benefits in one package.

As you can see from the image above the head of the group has a number of notches. It is possible to place your portafilter in these notches, then turn the head around to secure it. There is also a gasket made from rubber that resides inside the notches, which helps create the seal when you insert your portafilter into the machine. The notches allow for an exact placement of the portafilter. This is crucial to ensure a consistent extraction.

The group head does not just allow you to insert your portafilter easily however, it also keeps an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket, ensuring the temperature is always right for extraction. It is important to remember that even a slight differences can make the distinction between a good and great espresso.

The Pump

The motorized pumps used in rotary espresso machines provide the nine atmospheric bar pressure required to extract espresso. This differs from manually operated piston machines that employ a lever. The pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger prior to being pushed through the ground coffee inside the group head.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both types of machines can degrade due to overuse and inadequate cleaning. They also create mechanical complexity that can lead to costly prices for even the simplest models.

Some espresso machines use steam pressure instead of a pump to make espresso. The drawback of this is that the same boiler that produces steam also increases the temperature of the water until it reaches boiling, which can lead to excessive extraction. Additionally these machines typically have to rebuild their pressure between cups, which requires time and energy.

Many espresso machines employ an rotary or vibrating pump, with a vibration model using a rotating disc that generates the pressure and an rotary model that pushes hot water through the grounds at high speed. Both machines can make excellent espresso, however rotary machines are quieter, more durable and less likely to break.

The Boiler

The boiler is what is used to heat the water to the right temperature for extraction. The steam that is created is then directed to the portafilter, which holds the espresso grounds. The steam is then channeled into the cup. During this process, the steam creates pressure to push through the grounds of the coffee. This creates a crema on the top of the espresso. This is a sign of a good espresso.

There are three kinds of espresso makers, and they differ in the kind of pump they use and the degree of heat that the espresso is. There are different ways in which the brew can be controlled and the dimensions of the cup the machine can produce.

The earliest espresso machines were steam type. The first espresso machines were steam types. The coffee tasted bitter and burned. The modern espresso machine was created by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker is a semi-automatic one with an electric pump. When people think of espresso machines, they envision these machines. If you have a semi-automatic machine you need to grind the beans and tamp them yourself but the pump provides regulated water flow and pressure. This is a great compromise between the human touch and mechanized consistency.

The Filter

Typically, espresso machines employ a filter to separate out the coffee grounds as they pass through the hot water. The filter is also a vital part of the temperature control system, as it keeps the machine from overheating.

It also improves flavor, as it allows for a more prolonged bloom time. This helps the beans to release their flavors and provides an opportunity for better extraction.

However it is crucial to keep in mind that even a top filter can produce a bad cup of coffee, because the quality of the beans and extraction is still important.

This is where the magic happens. It's what makes an espresso really taste great. The grouphead, often referred to as the brew head, is where the portafilter (the thing you put the coffee grounds into) is placed when you're making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to make steam. The steam then moves hot water through the grounds of the best coffee espresso machine under pressure. These machines are less expensive and are easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.

In recent years, espresso machines driven by a compressed air pump have become 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.