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How Does Machine Espresso Work? The machine espresso utilizes precise pressure and filter technology that is mind-blowing to create the coffee you enjoy. What exactly does it work? In order to make espresso, hot water is forced under high 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 As the name implies, the group head is the place you place your portafilter while making espresso. It disperses water in the portafilter, and controls the pressure of the extraction. There are a variety of group heads each with distinct advantages and drawbacks. Some are designed for stability of temperature while others are built to handle pre-infusion. Others are built to control the lever. There are even some that come with a range of features, such as the E61 one, which is to be the most popular among baristas due to its ability to provide multiple benefits in one package. As you can see from the image above the head of the group is fitted with a variety of notches. The portafilter is placed in these notches, then twist the head to secure it. A gasket of rubber is situated inside the notches, which helps create a seal when you insert your portafilter. The notches on the head allow for a precise positioning of the portafilter which is essential to ensure a consistent extraction. The group head not only lets you to insert your portafilter easily, but it also maintains an even temperature. It does this by cycling hot water through the brew basket and around the portafilter, making sure that it is always at the correct temperature for extraction. This is important because just a few degrees could be the difference between a excellent and great espresso. The Pump Unlike manual piston machines, which rely on a lever that pressurize water, the rotary espresso machines use motorized pumps to supply the nine atmospheric bars of pressure necessary for espresso extraction. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee. Pumps are typically less expensive and last longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of frequent use and poor cleaning. They also make mechanically complex, which can result in a high price tag on even the simplest models. Some espresso machines remove the pump completely and employ steam pressure to create espresso. This can cause over-extraction because the boiler that makes steam also causes the water to boil. In addition the machines often have to rebuild their pressure between cups, which takes time and energy. Many espresso machines make use of a rotary or vibration pump. A vibration model makes use of an oscillating disk to create pressure, while the Rotary model pushes hot coffee through the ground at high speed. Both types of machines can make excellent espresso, however rotary machines are quieter and more durable than vibration pumps. The Boiler The boiler is the component that heats the water to the ideal temperature for extraction. The steam that is produced reaches the portafilter, which contains the ground espresso and is then pumped into the cup. In this process, the steam causes pressure to push through the coffee grounds. This results in a crema on top of the espresso. This is one of the main characteristics of a good espresso. There are three types of espresso makers. They differ in the type of pump they use and how hot the coffee is. There are a variety of ways to control the brew as well as the size of the cup that can be made by the machine. The first espresso machines were steam-types. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burnt. machines espresso machines was created by the Milanese makers Luigi Bezzerra & Desiderio Pavoni. The most popular espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp the beans by yourself while the pump controls the water flow and pressure. This is a great compromise between the human touch and the mechanised quality. The Filter Espresso machines typically use a filter that separates the grounds of the coffee from the hot water. The filter is also a vital component of the temperature control system since it helps prevent the machine from overheating. A filter can also help with flavor, as it permits a longer flowering phase. This lets the beans release their flavors, and allows for a better extraction. However it is crucial to remember that even a good filter can produce a bad cup of coffee, since the quality of the beans and extraction is still essential. This is where the magic happens, it's the thing that makes an espresso really taste good. The grouphead (also called the brewhead) is where you put the portafilter, the device used to place the grounds of coffee into when making espresso. Steam-driven espresso machines use hot water heated in an airtight vessel to create steam. The steam then moves hot water through 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 for creating the ideal conditions for brewing since they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars. In recent years, espresso machines powered by compressed air-pump have become increasingly popular. They use an air compressor to push hot water through the grounds, and are far more portable than electric steam-driven machines.