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How Does Machine Espresso Work?

Machine cheap espresso machine employs precise pressure and mind-blowing filter technology to create the perfect cup of coffee. 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 main difference lies in the pressure.

The Group Head

The group head is the portafilter that you put in when making espresso. It disperses the water into the portafilter, and regulates the pressure of the extraction. There are a variety of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, some on pre-infusion capabilities, and still others are designed to control the lever. There are also some that have a combination of features, such as the E61, which is to be the most popular among baristas due to its capacity to provide multiple benefits in one package.

As you can see in the above photo, the group head has many notches in which you can place your portafilter and twist it by hand to secure it. There is also a gasket made from rubber which is located inside the notches to help create an airtight seal when you insert your portafilter into the machine. The notches on the head allow for an exact positioning of the portafilter which is vital to ensure a consistent extraction.

In addition to allowing you easily place your portafilter in, the group head is also responsible for maintaining a consistent temperature. It does this by cycling hot water through the brew container and around the portafilter, ensuring that it's always at the correct temperature to extract. This is important because just a few degrees could mean the difference between good and great espresso.

The Pump

The motorized pumps in espresso machines rotary provide nine atmospheric bars of pressure required for espresso extraction. This differs from manual piston machines that use a lever. The pressure is created by drawing 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 generally less expensive than piston-driven machines, and tend to last longer, but both types of machines could be damaged by excessive use and inadequate cleaning. They also increase the complexity of mechanical systems that can lead to an expensive price for even the simplest models.

Some espresso machines make use of steam pressure instead of a pump for brewing espresso. This can result in over-extraction because the boiler that makes steam also heats the water to boil. Additionally these machines are often required to rebuild their pressure between cups, which takes time and energy.

Many espresso machines use the rotary or vibration pump. A vibration model uses a rotating disk to generate pressure, whereas a circular model pushes hot liquid through the ground at a high speed. Both types of machine are capable of producing excellent espresso, however rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler will heat the water to the ideal temperature to extract. The steam created will eventually reach the portafilter, which contains the espresso coffee grounds. It is then pumped into the cup. During this process, steam creates pressure that pushes through the coffee grounds. This creates a foam on the top of the espresso. This is one of the main characteristics of a good espresso.

There are three kinds of espresso makers, which differ in the kind of pump they use and the degree of heat that the brew is. There are different ways in which the brew could be controlled and the size of the cup the machine is capable of making.

The first espresso machines were steam-type. They had one boiler to make both brew and steam, however, the pressure they could produce was very low - just two bars of atmospheric pressure at the most. The coffee tasted bitter and burned. The modern espresso machine was invented by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker is a semiautomatic machine with an electric pump. These are what people imagine when they think of an espresso machine. With a semi-automatic machine you need to grind the beans and then tamp them yourself but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanized accuracy.

The Filter

Typically, espresso machines utilize filters to separate the coffee grounds as they pass through the hot water. The filter is also a vital component of the machine's temp control, since it helps to prevent overheating.

A filter also improves flavor since it allows for a longer flowering phase. This lets the beans let their nuances out, and allows for better extraction.

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

It's in this area that the magic happens. This is what makes espresso taste so delicious. The grouphead, often referred to as the brewhead, is where the portafilter (the thingy you put the coffee ground into) is placed when making espresso.

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

In recent years, compressed air-driven espresso machines have become more popular. They make use of an air compressor to push hot water through the ground. They are also more mobile than electric steam-driven espresso machines.