Laurene Kilgore

How Does machine espresso, extra resources, Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly is it?

Espresso is produced by pushing hot water at high pressure through finely ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.

The Head of the Group

As the name implies, the group head is the place you put your portafilter in when making 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 particular advantages and drawbacks. Some focus on temperature stability, while others on pre-infusion options, and others are designed to control the lever. There are some that come with a range of features, such as the E61 one, which is the classic choice among many baristas due to its ability to provide multiple benefits in a single package.

As you can see in the above image, the group head has several notches to put your portafilter, then twist it manually to secure it. A gasket made of rubber is placed in the notches to create a seal while you insert your portafilter. The notches allow for precise placement of your portafilter. This is crucial to ensure an accurate extraction.

The group head is not just able to allow the portafilter to be inserted easily however it also keeps the temperature at a constant level. This is achieved by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is always at the right level to extract the coffee. This is important, as just a few degrees could mean the difference between good and excellent espresso.

The Pump

Unlike manual piston machines espresso machines, which rely on a lever to pressurize water, rotating espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure required for espresso extraction. The pressure is created 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, however both types of machines could be damaged by excessive use and inadequate cleaning. They also make mechanically complex and can lead to a high price tag on even the most basic models.

Certain espresso machines utilize steam pressure instead of a pump to make espresso. The drawback is that the boiler that produces steam also raises the temperature of the water to boiling, which can lead to over-extraction. They also have to constantly rebuild their pressure in between cups. This requires energy and time.

A majority of espresso machines use an rotary or vibrating pump, with a vibration model using a rotating disc to create pressure, and the rotary model pushing hot water through the grounds under high speed. Both machines can produce excellent espresso, however rotary machines are more quiet, durable and less likely to fail.

The Boiler

The boiler is the element which heats the water to the ideal temperature to extract. The resultant steam then reaches the portafilter that contains the ground retro espresso machine and is then pumped into the cup. During this process the steam creates enough pressure to push the grounds of coffee through. This produces a layer of crema that is then poured over. This is a sign of a great espresso.

There are three types of espresso machines, each having a different type of pump and the temperature of the brew. There are various ways that the brew can be controlled and the size of the cup that the machine is capable of making.

The earliest espresso machines were steam-based. They had one boiler to make both steam and brew but the pressure they could generate was low - only two bars of atmospheric pressure maximum. This led to the coffee tasting bitter and burnt. The modern espresso machine was developed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso machine is a semiautomatic one with an electric pump. When people think of espresso machines, they envision these machines. 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 an excellent compromise between human touch and the mechanized accuracy.

The Filter

Espresso machines usually use a filter that separates the grounds of the coffee from the hot water. The filter is also an important part of the temperature control system as it keeps the machine from overheating.

It also enhances flavor, as a filter can allow for a longer bloom time. This lets the beans release their flavor and improves extraction.

It is important to keep in mind that even the best small espresso machine filter can produce a bad cup of coffee. The quality espresso machine of the beans and the extraction process, are still crucial.

This is where the magic happens, it's the thing that makes espresso taste good. The grouphead (also known as the brewhead) is where you place the portafilter, the device which you put the coffee grounds in, when making mini espresso maker.

Steam-driven espresso machines make use of hot water heated in an airtight container to produce steam. The steam then moves hot water through the grounds of coffee under high pressure. These kinds of machines tend to be less expensive and simpler to maintain than pump-driven models. They are however limited in their ability to create the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent times, espresso machines powered by a compressed air compressor have become increasingly popular. They use an air-compressor to push hot water across the ground, and are more mobile than steam-driven electric espresso machines.