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How Does Machine Espresso Work? Machine espresso makes use of precise pressure and incredible filter technology to produce the coffee we love. How does it work exactly? Espresso is created by forcing hot water under pressure through finely ground coffee. The process is similar to making drip coffee. However, it is the pressure that makes the main difference. The Group Head The group head is the portafilter that you place in the espresso maker when making it. It disperses the water into the portafilter and regulates the pressure during the extraction. There are a variety of types of group heads, each with their particular advantages and disadvantages. espressomachines are designed for stability of temperature while others are specifically designed to handle pre-infusion. Others are built to control the lever. There are also some that come with a range of features, like the E61 one, which is the classic choice among many baristas for its ability to provide multiple benefits in one package. As you can see in the above image the group head comes with numerous notches that you can place your portafilter before twisting it with your hands to lock it in. A gasket made of rubber is positioned inside the notches to help create a seal when you insert your portafilter. The notches on the head permit an exact location of the portafilter which is crucial for an efficient extraction. Aside from allowing you to easily connect your portafilter, the group head is also responsible for maintaining a consistent temperature. It does this by circulating hot water through the brew basket, and around the portafilter, ensuring that it is always at the right temperature for extraction. It is crucial to keep in mind that even a few degree variation can mean the difference between a good and a great espresso. The Pump The motorized pumps that are used in espresso machines rotary provide nine atmospheric bar pressure required for espresso extraction. This differs from manual piston machines that rely on levers. The pressure is created 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 may degrade because of excessive use and poor cleaning. They also add mechanical complexity and can lead to an expensive price for even the most basic models. Some espresso machines do away with the pump completely and instead utilize steam pressure to make espresso. This can result in over-extraction because the boiler that produces steam also heats the water to boil. Additionally the machines often have to restore their pressure between cups, which requires time and energy. Many espresso machines make use of a vibration or rotary pump, with a vibration model that uses a vibrating disc to generate the pressure and an rotary model that pushes hot water through the grounds at high speed. Both machines produce great espresso, but rotary machines are more stable, quieter and less likely to break down. The Boiler The boiler is the component that heats the water to the optimal temperature to extract. The steam produced is then directed to the portafilter, which is a container for espresso grounds. The steam is then channeled into the cup. During this process the steam creates enough pressure to push the coffee grounds through. This creates a crema on top of the espresso. This is a sign of a good espresso. There are three kinds of espresso makers, and they differ in the type of pump they employ and how hot the brew is. There are different ways to control the strength of the brew and the size of the cup that can be produced by the machine. The first espresso machines were steam-types. The first espresso machines were steam-type machines. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese producers Luigi Bezzerra & Desiderio Pavoni. The most common espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic machine you must grind the beans and tamp them by hand, but the pump controls the flow of water and pressure. This is an excellent combination of human control and mechanised accuracy. The Filter Typically, espresso machines utilize a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also a vital component of the machine's temperature control, since it helps to prevent overheating. A filter can also help with flavor because it allows for an extended flowering time. This allows the beans to let their nuances out and provides an opportunity to improve extraction. It is important to remember that even the most efficient filter can make a bad cup of coffee. The quality of the beans and the extraction process, remain crucial. This is where the magic happens. It's what makes espresso taste great. The grouphead (also called the brewhead) is where you put the portafilter, the device that you use to put the coffee grounds into, when making espresso. Steam-driven espresso machines make use of hot water heated in an airtight container to create steam. The steam then moves hot water through the grounds of coffee at high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. They are however limited for creating the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars. In recent years, compressed air pump-driven espresso machines have been gaining popularity. They use an air compressor to force hot water through the ground and are more mobile than electric steam-driven espresso machines.