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How Does Machine Espresso Work? The machine espresso uses precise pressure and filter technology that is awe-inspiring to make the coffee you enjoy. But how exactly does it work? Espresso is made by forcing hot water at high pressure through finely-ground coffee. The process is similar to that of making drip coffee. However, the pressure is the major difference. The Head of the Group As the name implies the group head is where you put your portafilter in when brewing espresso. It disperses water in the portafilter and controls the pressure of the extraction. There are many different types of group heads each with its own advantages and disadvantages. Some are designed for stability in temperature, while others are designed to handle pre-infusion. Others are built to control the lever. Some have a combination, such as the E61. This is a very popular choice for baristas as it provides a variety of advantages in one package. As you can see in the image above the group head is made up of several notches to place your portafilter and twist it with your hands to lock it in. There is also a gasket made from rubber which is located inside the notches and helps to create an airtight seal after inserting your portafilter into the machine. The notches permit precise placement of the portafilter. This is crucial to ensure an efficient extraction. The group head not only lets you to insert your portafilter easily however it also keeps the same temperature. This is done by cycling hot water around the portafilter and through the brew-basket, making sure that the temperature is at the right level for extraction. This is important, as even a few degrees can make the difference between a good and excellent espresso. The Pump In contrast to manual piston machines that use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure that are required to extract espresso. The pressure is created by removing 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 typically more affordable and last longer than piston-driven machines. However, both types of machines can degrade due to overuse and poor cleaning. Pumps are also more complex mechanically, which can increase the price of even the simpler models. Some espresso machines remove the pump completely and instead make use of steam pressure to make espresso. The downside is that the same boiler that produces steam also raises the temperature of water to boiling which can cause over-extraction. These machines also have to constantly rebuild their pressure in between cups. This requires energy and time. Many espresso machines make use of an rotary or a vibration pump. A vibration model makes use of the vibrating disk to create pressure, while a rotary model pushes hot water through the ground at a high speed. Both models can make a great espresso, however Rotary machines are quieter and more durable than vibration pumps. The Boiler The boiler is the component which heats the water to the optimal temperature for extraction. The steam produced reaches the portafilter, which is a container for espresso grounds. It is then funneled into the cup. During this process, steam creates pressure to push through the coffee grounds. This creates a foam on the top of the espresso. This is one of the hallmarks of a good espresso. There are three types of espresso machines, each with different types of pumps and brew temperature. There are also different ways in which the brew could be controlled as well as the size of the cup that the machine is capable of making. The first espresso machines were steam types. The first espresso machines were steam types. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was developed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni. The most well-known espresso maker is a semi-automatic machine with an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic machine, you grind the beans and then tamp them by hand. However, the pump regulates the flow of water and pressure. best portable espresso makers is a great compromise between human control and mechanized consistency. The Filter Typically, espresso machines use filters to separate the grounds of coffee when they pass through the hot water. The filter is also a vital component of the machine's temp control, as it helps prevent overheating. A filter also improves flavor as it allows for a longer flowering period. This allows the beans to release their nuances, and allows for a better extraction. It is important to keep in mind that even the most efficient filter could result in a poor cup of coffee. The quality of the beans, and the extraction process, are still crucial. It's here that the magic takes place. This is what makes espresso taste so good. The grouphead, sometimes referred to as the brew head, is where the portafilter (the thing you put the coffee grounds into) sits when you're making espresso. Steam-driven espresso machines use hot water that is heated in an airtight container to make steam. The steam then moves hot water through the grounds of coffee at high pressure. They are less expensive and easier to maintain than pumps-driven models. However, they are limited in their ability to provide the perfect brewing conditions because they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar. In recent years, compressed air-driven espresso machines have been gaining popularity. They utilize an air compressor to push hot water into the grounds, and are far more portable than steam-driven electric machines.