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How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to make the delicious coffee we enjoy. 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 espresso machines but the difference is in the pressure.

The Group Head

The group head is the portafilter you put in when making espresso. It disperses water in the portafilter, and regulates the pressure during the extraction. There are a variety of types of group heads, each with their particular advantages and drawbacks. Some are focused on temperature stability, while others on pre-infusion capabilities, and still others are designed to control the lever. Some come with a combination of both, like the E61. This is a popular choice among baristas as it provides a variety of benefits in one package.

As you can see from the image above, the group head is fitted with a variety of notches. You place your portafilter in these notches and then twist the head to lock it. There is also a rubber gasket that is a part of the notches to help create the seal when you insert your portafilter into the machine. The notches on the head allow for an exact placement of the portafilter, which is necessary to ensure an efficient extraction.

The group head does not just allow you to put in your portafilter easily but also maintains an even temperature. It does this by cycling hot water through the brew basket and around the portafilter, making sure that it's always at the correct temperature for extraction. It is important to realize that even a slight differences can make the distinction between a good and excellent espresso.

The Pump

Unlike manual piston machines, which rely on a lever to pressurize water, Rotary commercial espresso machine machines rely on motorized pumps to provide the nine atmospheric bars of pressure necessary for espresso extraction. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger prior to it is shot through the ground coffee inside the group head.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both types of machines may degrade because of frequent use and poor cleaning. Pumps are also more complicated mechanically, which can raise the cost of even simple models.

Some retro espresso machine machines make use of steam pressure instead of a pump in order to brew espresso. The disadvantage of this is that the same boiler that produces steam also increases the temperature of the water to boiling, which can lead to excessive extraction. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

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

The Boiler

The boiler will heat the water to the ideal temperature to extract. The steam produced gets to the portafilter which contains the espresso coffee grounds. It is then poured into the cup. During this process, steam creates pressure to push through the grounds of the coffee. This creates a layer crema on top. This is one of the hallmarks of a good espresso.

There are three types of espresso makers. They differ in the kind of pump they use and how hot the brew is. There are also different ways in which the brew can be controlled as well as the size of the cup that the machine can produce.

The earliest espresso machines were steam types. The earliest espresso machines were steam types. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was designed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso machine is a semiautomatic model with an electric pump. These are what people imagine when they imagine an espresso machine. With a semi-automatic machine you need to grind the beans and tamp them by hand, but the pump regulates the flow of water and pressure. This is a great compromise between the human touch and mechanized quality.

The Filter

Typically, espresso machines utilize filters to separate the grounds of coffee as they move through the hot water. The filter is also an essential element of the temperature control system, because it stops the machine from overheating.

It also improves flavor, since a filter allows for a more prolonged bloom time. This helps the beans to release their nuances and gives an opportunity for better extraction.

However, it is important to keep in mind that even a high-quality filter can produce a bad cup of coffee, since the quality of the beans and extraction are crucial.

This is where the magic happens. It's what makes espresso taste great. The grouphead, also called the brewhead, is where the portafilter (the thingy you put the ground coffee into) is placed when you're making espresso.

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

In recent years, compressed air pump-driven espresso machines have become more popular. They use an air compressor to push hot water into the grounds and are much more portable than steam-driven electric machines.