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How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and incredible filter technology to produce the coffee we love. How exactly does it work?

Espresso is created by forcing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee, however the main difference lies in the pressure.

The Group Head

The group head is the portafilter you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter before controlling the pressure of the resulting extraction. There are many different types of group heads each with its own advantages and drawbacks. Some are designed to provide the stability of temperature while some are built to handle pre-infusion. Others are made to control the lever. There are some that come with a range of features, like the E61 one, which is the most popular choice among baristas due to its ability to offer multiple perks in one package.

As you can see from the above photo the head of the group has a number of notches. You place your portafilter in these notches, then turn the head around to secure it. A rubber gasket is located inside the notches, which helps create a seal when you insert your portafilter. The notches allow for an exact placement of the portafilter. espresso machine uk is vital for an even extraction.

The group head not only allows you to place your portafilter easily however it also keeps a constant temperature. It does this by circulating hot water through the brew basket, and around the portafilter, making sure that it is always at the correct temperature to extract. This is important, as even a small difference in temperature can make the difference between a good and excellent espresso.

The Pump

The motorized pumps in espresso machines rotary provide nine atmospheric bar pressure needed to extract espresso. This is different from manual piston machines which use a lever. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are generally less expensive than piston-driven machines, and tend to last longer, however both types of machines may be damaged by excessive use and inadequate cleaning. They also create mechanical complexity, which can result in costly prices for even the most basic models.





Some espresso machines employ steam pressure instead of a pump to brew espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of water to the point of boiling which can cause excessive extraction. The machines must also constantly rebuild their pressure between cups. This takes energy and time.

A majority of espresso machines use an rotary or vibrating pump, with a vibration model using a rotating disc to create the pressure and rotating models that push hot water through the grounds under high speed. Both types of machines can produce an excellent espresso, but the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is what makes the water warm to the right temperature for extraction. The resulting steam is then transferred to the portafilter, which contains the ground espresso coffee, and gets funnelled down into the cup. During this process the steam generates enough pressure to push the grounds of coffee through. This results in a layer crema that is then poured over. This is a sign of a great espresso.

There are three kinds of espresso makers. They differ in the type of pump they employ and how hot the coffee is. There are a variety of ways to control the brew as well as the size of cup that can be made by the machine.

The first espresso machines were steam-types. They employed only one boiler to make steam and brew, but the pressure they could produce was not very high - two bars of atmospheric pressure maximum. The coffee tasted bitter and burned. The modern espresso machine was developed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso machine is a semiautomatic one with an electric pump. This is what people envision when they think of an espresso maker. With a semi-automatic machine, you need to grind the beans and then tamp them by hand, but the pump controls the flow of water and pressure. This is a perfect solution that combines human control with mechanized accuracy.

The Filter

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

Filters also aid in flavor as it allows for an extended flowering time. This allows the beans to release their nuances, and also allows for better extraction.

However it is crucial to remember that even a great filter could result in a bad cup of coffee, as the quality of the beans and extraction are important.

It's here that the magic happens. This is what makes espresso taste so good. The grouphead (also called the brewhead) is where you place the portafilter, which is the thingy used to place the grounds of coffee into when making espresso.

In a steam-driven espresso machine hot water is heated in an airtight tank to produce steam, which then pushes the hot water through the grounds under high pressure. These types of machines are generally less expensive and easier to maintain than pump-driven models. However, they are not as efficient in their ability to provide the ideal conditions for brewing since they are only operating at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars.

In recent times, espresso machines powered by compressed air-pump are becoming increasingly popular. They use an air compressor to force hot water through the ground. They are also more mobile than steam-driven electric espresso machines.