How Does Machine Espresso Work?

Machine espresso employs precise pressure and mind-blowing filter technology to make the perfect cup of coffee. What exactly does it work?

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

The Head of the Group

The name implies, the group head is the place you insert your portafilter when brewing espresso. It disperses water in the portafilter and regulates the pressure of the extraction. There are several different types of group head each with its distinct advantages and drawbacks. Some are designed to provide the stability of temperature while some are designed to handle pre-infusion. Others are built to control the lever. Some have a combination, such as the E61. This is a favorite among baristas due to the fact that it has multiple benefits in one package.

As you can see in the above photo, the group head has a number of notches. You place your portafilter into these notches and twist the head to secure it. There is also a gasket made of rubber that is a part of the notches, which helps create a seal when you insert your portafilter into the machine. The notches permit an exact placement of the portafilter. This is essential for an efficient extraction.

The group head not only lets you to put in your portafilter easily however, it also keeps an even temperature. It does this by cycling hot water through the brew container and around the portafilter to ensure that it's always at the right temperature for extraction. This is crucial, since just a few degrees could make the difference between good and great espresso.

The Pump

Unlike manual piston machines, which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure needed to extract espresso. The pressure is created 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, although both types of machines can get damaged through overuse and lack of cleaning. They also add mechanical complexity that can lead to costly prices for even the simplest models.

Some mini espresso maker machines do away with the pump completely and instead use steam pressure to brew espresso. The drawback is that the boiler that produces steam also increases the temperature of the water to boiling and can result in over-extraction. The machines must also constantly rebuild their pressure in between cups. This requires energy and time.

A large majority of espresso machines employ an rotary or a vibration pump. A vibration model employs a vibrating disk to generate pressure, while a circular model pushes hot liquid through the ground at a rapid speed. Both machines can produce excellent espresso however rotary machines tend to be quieter, more durable and less likely to fail.

The Boiler

The boiler is the one that will heat the water to the perfect temperature for extraction. The steam that is produced reaches the portafilter that contains the ground espresso coffee and is then pumped into the cup. During this process the steam is able to create enough pressure to push the coffee grounds through. This results in a layer of crema on top. This is one of the hallmarks of a good espresso.

There are three kinds of espresso makers. They differ in the kind of pump they use and the degree of heat that the espresso is. There are many 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 both steam and brew however, the pressure they could generate was low - only two bars of atmospheric pressure at most. This resulted in the coffee tasting burnt and bitter. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most popular espresso maker is a semi-automatic device that has an electric pump. These are what people imagine when they think of an espresso coffee machines for sale machine. Semi-automatic machines require you to grind and tamp the beans by yourself The pump, however, regulates the water flow and pressure. This is a perfect compromise between human control and mechanised accuracy.

The Filter

Espresso machines typically have filters that separate the coffee grounds from the hot water. The filter is also a vital component of the machine's temperature control, since it stops overheating.

A filter can also help with flavor as it allows for a longer flowering phase. This allows the beans to release their flavor and allows for a better extraction.

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

It's here that the magic takes place. This is what makes espresso machines uk taste so good. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy that you use to put the coffee grounds into, when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. Steam is then pushed through the grounds at high pressure. They are less expensive and easier for the owner to maintain than pumps-driven models. However, they are limited in their ability to produce the ideal conditions for brewing because they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.

In recent years, espresso machines powered by a compressed air compressor have become increasingly popular. They utilize an air compressor to force the hot water through the grounds and are much more portable than steam-driven electric machines.