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How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and mind-blowing filter technology to make the perfect cup of coffee. How exactly does it work?

To make espresso hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However it is the pressure that makes the main difference.

The Group Head

The group head is the portafilter you put in when making espresso. It disperses water in the portafilter, and then regulates the pressure of the extraction. There are a variety of types of group head each with its unique advantages and drawbacks. Some are designed for stability of temperature while others are designed to handle pre-infusion. Others are made to control the lever. There are also some that include a mix of features, such as the E61, which is considered the most popular choice among baristas due to its capacity to provide multiple benefits in one package.

As you can see from the image above the group head is equipped with several notches. It is possible to place your portafilter in these notches, then turn the head around to secure it. A gasket made of rubber is placed inside the notches to help create a seal while you insert your portafilter. The notches on the head permit an exact placement of the portafilter, which is necessary to ensure a consistent extraction.

The group head not only lets you to put in your portafilter easily but also maintains an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is constant for extraction. This is crucial, since just a few degrees could be the difference between a excellent and great espresso.

The Pump

The motorized pumps that are used in espresso machines rotary provide nine atmospheric bar pressure required to extract espresso. This differs from manual piston machines that rely on levers. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pushed through the ground coffee in the group head.

Pumps are generally cheaper and last longer than piston-driven machines. However, both types of machines are susceptible to degrading due to overuse and inadequate cleaning. They also increase the complexity of mechanical systems, which can result in the cost of even the simplest models.

Some espresso machines eliminate the pump completely and instead employ steam pressure to create espresso. The downside is that the boiler that produces steam also raises the temperature of water until it reaches boiling, which can lead to over-extraction. They also have to constantly 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 that uses a vibrating disc that generates the pressure, and the rotary model pushing 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 break down.

The Boiler

The boiler is the element that heats water to an optimal temperature to extract. The steam that is produced reaches the portafilter that contains ground espresso coffee machines for sale beans and is then funneled down into the cup. During this process, the steam causes pressure to push through the grounds of the coffee. This results in a layer crema that is then poured over. This is the hallmark of a great espresso.

There are three kinds of espresso machines, each with different types of pumps and brew temperature. There are a variety of ways in which the brew could be controlled as well as the size of the cup that the machine can produce.

The first espresso machines were steam-types. They had only one boiler to make both brew and steam, however the pressure they were able to create was minimal - two bars of atmospheric pressure at most. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso maker is a semi-automatic espresso machine device with an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic machine, Espressomachines you grind the beans and then tamp them by hand, but the pump is able to regulate the flow of water and pressure. This is an excellent compromise between human touch and the mechanized consistency.

The Filter

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

Filters also aid in flavor since it allows for a longer flowering period. This allows the beans to release their flavors and provides the chance for better extraction.

However, it is important to keep in mind that even a great filter could result in a bad cup of coffee, since the quality of the beans and extraction is still vital.

This is where the magic happens, it's what makes espresso taste great. The grouphead, often called the brew head, is the place where the portafilter (the thing you put the ground coffee in) is placed when you're making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight vessel to create steam. The steam then pushes hot water through coffee grounds under high end espresso machine pressure. These kinds of machines are generally cheaper and easier to maintain than pump-driven models. However, they are limited in their ability to produce the perfect brewing conditions as they only operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.

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