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How Does Machine Espresso Work? Machine espresso utilizes precise pressure and mind-blowing filter technology to make the coffee we love. How does it work exactly? Espresso is created by forcing hot water at high pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the main difference. The Head of the Group As the name suggests the group head is where you place your portafilter while making espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure that results from the extraction. There are several different types of group heads, each with their distinct advantages and disadvantages. Some are specifically designed for the stability of temperature while some are specifically designed to handle pre-infusion. Some are designed to control the lever. Some include a mix of features, like the E61, which is the most popular choice among baristas due to its ability to offer multiple benefits in one package. As you can see in the above image The group head features several notches where you put your portafilter, then twist it manually to lock it in. A gasket of rubber is situated within the notches to create a seal when you insert your portafilter. The notches allow for 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 but also maintains the temperature at a constant level. It does this by circulating hot water through the brew container and around the portafilter to ensure that it is always at the correct temperature to extract. It is important to remember that even a small variation can mean the difference between a good and great espresso. The Pump Unlike manual piston machines, which rely on a lever to pressurize water, rotating espresso machines rely upon motorized pumps to deliver the nine atmospheric bars of pressure that are required to extract espresso. The pressure is built by pumping water through a heat-exchanger and then through the ground coffee. Pumps tend to be cheaper and last longer than piston-driven machines. However, both kinds of machines can deteriorate due to excessive use and insufficient cleaning. Pumps are also more complex mechanically, which can increase prices of even most basic models. Some espresso machines can eliminate the pump entirely and utilize steam pressure to make espresso. This can lead to over-extraction as the boiler that produces steam also heats the water until it comes to a boil. Additionally, these machines frequently have to rebuild their pressure between cups, which takes time and energy. Many espresso machines employ a vibration or rotary pump, which has a vibration model using a vibrating disc to generate the pressure and a rotary model pushing hot water through the grounds at high speed. Both types of machine can produce an excellent espresso, however the rotary models are quieter and more durable than vibration pumps. The Boiler The boiler is the element that heats water to the optimal temperature for extraction. The steam produced will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. It is then funneled into the cup. During this process the steam generates enough pressure to push the coffee grounds through. This produces a layer of crema on top. This is one of the hallmarks of a great espresso. There are three different types of espresso machines, each having a different type of pump and brew temperature. There are various ways to control the brew as well as the size of cup that can be made by the machine. The first espresso machines were steam-type. They used one boiler to create steam and brew, however the pressure they were able to produce was very low – just two bars of atmospheric pressure at most. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni. The most well-known espresso maker is a semiautomatic machine that has an electric pump. These are the things people think of when they think of an espresso machine. Semi-automatic machines require you to grind and tamp the beans yourself however the pump controls the flow of water and pressure. This is a great solution that combines human control with mechanized reliability. The Filter Typically, espresso machines employ filters that separate the coffee grounds as they pass through the hot water. The filter is also a vital element of the machine's temperature control, since it stops overheating. A filter also helps with flavor as it allows for a longer flowering period. This helps the beans to let their nuances out and provides an opportunity for better extraction. It is important to keep in mind that even the finest filter can make a bad cup of coffee. The quality of the beans and the extraction process, are still very important. It's here that the magic happens. This is what makes espresso taste so good. The grouphead (also called the brewhead) is where you put the portafilter, which is the thingy used to place the grounds of coffee into when making espresso. In the steam-driven espresso machine hot water is heated in an airtight container to create steam, which is then pushed through the grounds with high pressure. espresso coffee machines are less expensive and are easier for the user to maintain than pumps-driven models. They are however limited to create the perfect conditions for brewing as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars. In recent years, compressed-air-pump-driven espresso machines have become more popular. They make use of an air compressor to push hot water across the ground. They are also more mobile than steam-driven electric espresso machines.