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How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to make the coffee we love. What exactly does it work?

espresso coffee machine with milk frother is made by pushing hot water under pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.

The Head of the Group

The group head is the portafilter is inserted when you are making espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure of the extraction. There are a variety of group heads each with distinct advantages and disadvantages. Some focus on temperature stability, others on pre-infusion features, and others are designed to control the lever. Some come with a combination of both, like the E61. This is a favorite among baristas because it offers multiple advantages in one package.

As you can see from the image above, the group head has a number of notches. You can place your portafilter in these notches and then twist the head to secure it. There is also a gasket made from rubber in the notches and helps to create a seal when you insert your portafilter into the machine. The notches allow for the precise placement of the portafilter. This is crucial for an efficient extraction.

The group head not only lets you to insert your portafilter easily however, it also keeps the temperature at a constant level. This is done by cycling hot water around the portafilter, and through the brew-basket, making sure the temperature is always right to extract the coffee. This is vital, because even a small difference in temperature can be the difference between a good and great espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, the rotary espresso machines use motorized pumps to provide the nine atmospheric bars of pressure required for espresso extraction. This pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger before it is shot through the ground coffee in the group head.

Pumps are typically less expensive than piston-driven machines, and tend to last longer. However, both types of machines can be damaged by excessive use and inadequate cleaning. They also create mechanical complexity and can lead to the cost of even the simplest models.

Some espresso machines employ 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 best bean to cup espresso machine boiling which can cause over-extraction. The machines must also constantly rebuild their pressure between cups. This takes energy and time.

A majority of espresso machines utilize the rotary or vibration pump. A vibration model makes use of an oscillating disk to create pressure, while a circular model pushes hot liquid through the ground at a rapid speed. Both types of machine can make a great espresso, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is what will heat the water to the right temperature to extract. The steam that is produced reaches the portafilter, which contains ground espresso beans and is then pumped into the cup. In this process, the steam creates pressure to push through the grounds of the coffee. This results in a whipped-up top of the espresso. This is one of the hallmarks of a great espresso makers.

There are three types of espresso machines, each having different types of pumps and brew temperature. There are various ways in which the brew can be controlled, as well as the size of the cup the machine is capable of making.

The first espresso machines were steam-types. They utilized one boiler to make steam and brew, but the pressure they could produce was very low - just two bars of atmospheric pressure, at most. The coffee espresso machines tasted bitter and burnt. This is the reason Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso maker is a semi-automatic one that has an electric pump. These are the images people have when they think of an espresso maker. With a semi-automatic machine you must grind the beans and tamp them by hand. However, the pump regulates the flow of water and pressure. This is an excellent solution that combines human control with mechanized consistency.

The Filter

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

It also enhances flavor, as a filter can allow for a longer bloom phase. This allows the beans to release their nuances, and also allows for better extraction.

It is important to keep in mind that even the finest filter can result in a bad cup of coffee. The quality of the beans and the extraction, remain vital.

This is where the magic happens, it's what makes espresso taste good. The grouphead (also known as the brewhead) is where you place the portafilter, the thingy which you put the grounds of coffee into when making espresso capsule machine.

Steam-driven espresso machines use 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 machines are cheaper and easier to maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

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