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Will Machine Espresso Ever Be The King Of The World?
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 that makes it work?

Espresso is made by forcing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee. However the pressure is the major difference.

The Head of the Group

As the name implies, the group head is where you insert your portafilter when making espresso. It is responsible for dispersing the water into the portafilter before controlling the pressure of the resulting extraction. There are various kinds of group head each with its unique advantages and disadvantages. Some are designed for stability in temperature, while others are designed to handle pre-infusion. Others are built to control the lever. Some are a combination, like the E61. This is a favorite among baristas as it provides a variety of benefits in a single package.

As you can see from the picture above the head of the group is equipped with several notches. The portafilter is placed inside these notches, and then turn the head around to secure it. There is also a gasket of rubber that is a part of the notches and helps create a seal when you insert your portafilter into the machine. The notches on the head permit an exact location of the portafilter which is crucial to ensure a consistent extraction.

The group head not only lets you to put in your portafilter easily, but it also maintains the same temperature. It does this by circulating hot water through the brew pan and around the portafilter, making sure that it is always at the right temperature for extraction. It is important to note that even a small deviation can make the difference between a good and a great espresso.

The Pump

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

Pumps tend to be less expensive than piston-driven machines, and tend to last longer, although both types of machines can be damaged by excessive use and inadequate cleaning. They also create mechanical complexity, which can result in a high price tag on even the most basic models.

Certain espresso machines can eliminate the pump entirely and employ steam pressure to create espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of 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 make use of an rotary or vibrating pump, with a vibration model that uses a vibrating disc to create pressure and an rotary model that pushes hot water through the grounds under high speed. Both machines produce great espresso but rotary machines are quieter, more durable and less likely to break.

The Boiler

The boiler heats the water to a temperature that is ideal to extract. The steam that is created gets to the portafilter which is the container that holds the espresso coffee grounds. It is then poured into the cup. During this process the steam causes enough pressure to push the coffee grounds through. This creates a layer crema on top. This is one of the hallmarks of a great espresso.

There are three kinds of espresso makers. They differ in the type of pump they use and how hot the brew is. There are various ways to control the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam-type. They had one boiler to create steam and brew, however, the pressure they could generate was low - only two bars of atmospheric pressure at most. The coffee tasted bitter and burnt. This is why Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso maker is a semi-automatic device with an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp the beans on your own while the pump controls the flow of water and pressure. This is an excellent compromise between human touch and the mechanised quality.

The Filter

Typically, espresso machines use filters to separate the grounds of coffee when they pass through the hot water. The filter is also a vital element of the machine's temperature control, since it stops overheating.

It also enhances flavor, as it allows for a more prolonged bloom phase. This helps the beans to let their nuances out and provides the chance for better extraction.

However it is crucial to remember that even a top filter can make a terrible cup of coffee, since the quality of the beans and extraction are essential.

It's in this area that the magic happens. This is what makes espresso taste so delicious. The grouphead, also referred to as the brew head, is where the portafilter (the thing you put the ground coffee into) sits when you're making espresso.

In an espresso machine that is driven by steam, hot water is heated in an airtight tank to create steam. This then pushes the hot water through the grounds under high pressure. These kinds of machines are generally cheaper and easier to maintain than pump-driven models. They are however limited to create the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent years, compressed air-driven espresso machines have been gaining popularity. discover this use an air compressor to force the hot water through the grounds and are significantly more portable than steam-driven electric machines.