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We've Had Enough! 15 Things About Machine Espresso We're Sick Of Hearing
How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the coffee we love. How exactly does it work?

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

The Group Head

The group head is the portafilter that you put in when making espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the extraction. There are many different types of group heads, each with its own advantages and disadvantages. Some are focused on temperature stability, while others on pre-infusion capabilities, while others are designed to control the lever. Some have a combination of features, such as the E61 that is the standard choice for many baristas due to its capacity to provide multiple benefits in one package.

As you can see in the photo above, the group head is equipped with several notches. It is possible to place your portafilter in these notches and then twist the head to lock it. A rubber gasket is located inside the notches, which helps create a seal while you insert your portafilter. The notches allow for the precise placement of the portafilter. This is crucial to ensure an accurate extraction.

The group head is not just able to allow you to place your portafilter easily but also maintains the same temperature. It does this by cycling hot water through the brew container and around the portafilter, making sure that it's always at the right temperature for extraction. This is important because just a few degrees could be the difference between a good and great espresso.

The Pump

Unlike manual piston machines, that use a lever to pressurize water, rotating espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure needed to extract espresso. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.


Pumps tend to be less expensive and last for longer than piston-driven machines. However, both types of machines can degrade due to excessive use and inadequate cleaning. Pumps are also more complex mechanically, which could increase the cost of even the simple models.

Some espresso machines make use of steam pressure instead of a pump for brewing espresso. This can cause over-extraction because the boiler that makes steam also heats the water to boil. The machines must also constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines utilize a vibration or rotary pump, which is a vibration model using a vibrating disc to create the pressure, and the rotary model pushing hot water through the grounds under high speed. Both machines can produce excellent espresso however rotary machines tend to be quieter, more durable and less likely to break.

The Boiler

The boiler is used to heat the water to the ideal temperature to extract. The resultant steam then reaches the portafilter which holds ground espresso beans and is then pumped down into the cup. During this process, steam creates pressure that pushes through the grounds of the coffee. This creates a layer crema on top. This is one of the main characteristics of a great espresso.

There are three distinct types of espresso machines, each having a different type of pump and the temperature of the brew. There are a variety of ways in which the brew can be controlled and the dimensions of the cup the machine can make.

The earliest espresso machines were steam-based. They employed one boiler to create both steam and brew but the pressure they could create was minimal - two bars of atmospheric pressure at most. 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 model with 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 on your own, but the pump regulates the flow of water and pressure. This is a great compromise between the human touch and mechanized accuracy.

The Filter

Espresso machines usually use a filter that separates the grounds of the coffee from hot water. The filter is also an essential element of the temperature control system, because it stops the machine from overheating.

It also helps with flavor as a filter lets you enjoy a longer bloom time. This allows the beans to let their nuances out, and also allows for better extraction.

However it is crucial to keep in mind that even a great filter can result in a poor cup of coffee as the quality of the beans and extraction is crucial.

This is where the magic happens, it's what makes an espresso really taste good. The grouphead (also known as the brewhead) is where you place the portafilter, the device that you use to put the coffee grounds into, while making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to create steam. The steam then moves hot water through the coffee grounds under high pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. They are however limited 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 make use of an air compressor to push hot water through the ground, and are more mobile than steam-driven electric espresso machines.

Read More: https://www.coffeee.uk/categories/espresso-coffee-machines