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How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and incredible filter technology to produce the delicious coffee we enjoy. How exactly does it work?

Espresso is made by pushing hot water under pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the main difference.

The Head of the Group

As the name suggests, the group head is the place you place your portafilter when making Espresso Machine With milk frother. It distributes water into the portafilter, and regulates the pressure during the extraction. There are numerous kinds of group heads, each with its own advantages and drawbacks. Some are focused on temperature stability, while others on pre-infusion features, and others are designed to control the lever. Some are a combination, like the E61. This is a popular choice among baristas since it provides multiple benefits in a single package.

As you can see from the above photo the group head is fitted with a variety of notches. You can place your portafilter inside these notches, and then turn the head around to secure it. A gasket made of rubber is positioned within the notches to create a seal as you insert your portafilter. The notches allow for an exact placement of the portafilter. This is vital for an efficient extraction.

Aside from allowing you to easily place your portafilter in, the group head is responsible to maintain an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket to ensure that the temperature is at the right level to extract the coffee. It is important to realize that even a slight differences can make the distinction between a great and a great espresso.

The Pump

Motorized pumps in espresso machines that rotate provide the nine atmospheric bar pressure that is required to extract espresso. This differs from manual piston machines which use levers. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both types of machines are susceptible to degrading due to excessive use and insufficient cleaning. Pumps are also more complicated mechanically, which can raise prices of even simplest models.

Some espresso machines use steam pressure instead of a pump in order to brew espresso. This can cause over-extraction because the boiler that makes steam also warms the water to boil. Additionally, these machines frequently have to rebuild their pressure between cups, which takes time and energy.

A majority of espresso machines use an rotary or vibrating pump, espresso machine with milk frother with a vibration model using a vibrating disc to create the pressure and rotating models that push hot water through the grounds at high speed. Both machines can make great espresso but rotary machines are more stable, quieter and less likely to fail.

The Boiler

The boiler is the part that heats water to the ideal temperature to extract. The resulting steam is then transferred to the portafilter that contains the ground espresso and is then funneled down into the cup. During this process the steam is able to create enough pressure to push the coffee grounds through. This results in a crema on top of the espresso. This is the hallmark of a good espresso.

There are three distinct types of espresso machines, each with a different type of pump and the temperature of the brew. There are also different ways in which the brew can be controlled, as well as the dimensions of the cup the maker can create.

The earliest espresso machines were steam-based. They employed one boiler to make steam and brew, however, the pressure they could produce was not very high - two bars of atmospheric pressure maximum. The coffee tasted bitter and burnt. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most commonly used espresso machine is a semiautomatic with an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic espresso machine, you need to grind the beans and tamp them by hand, but the pump provides regulated water flow and pressure. This is a great compromise between the human touch and the mechanised quality.

The Filter

Typically, espresso machines have filters to separate the grounds of coffee and espresso maker when they pass through the hot water. The filter is also an essential part of the machine's temperature control, since it helps to prevent overheating.

It also improves flavor, as a filter lets you enjoy a longer bloom phase. This helps the beans release their flavor and gives an opportunity for better extraction.

It is important to keep in mind that even the finest filter could result in a poor cup of coffee. The quality of the beans and the extraction, are still very important.

This is where the magic happens, it's what makes espresso taste great. The grouphead (also known as the brewhead) is where you put the portafilter, the device used to place the grounds of your coffee into while making espresso.

Steam-driven espresso machines make use of hot water that is heated inside an airtight container to create steam. The steam then pushes 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 to create the ideal conditions for brewing since they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

In recent years, compressed air-driven espresso machines have been gaining popularity. They utilize an air compressor to force hot water through the ground, and are more mobile than electric steam-driven espresso machines.