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How Does Machine Espresso Work? Machine espresso employs precise pressure and mind-blowing filter technology to make the coffee we love. How does it work exactly? Espresso is produced by pushing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee. However the pressure is the primary difference. The Group Head The group head is the portafilter is inserted when you are making espresso. It disperses water in the portafilter, and controls the pressure of the extraction. There are a variety of group heads each with its own advantages and drawbacks. Some focus on temperature stability, some on pre-infusion options, and others are designed to control the lever. There are even some that have a combination of features, like the E61 one, which is the most popular choice among baristas due to its capacity to offer multiple perks in a single package. As you can see from the image above the group head has a number of notches. You can place your portafilter in these notches and then twist the head to lock it. There is also a gasket of rubber that is a part of the notches and helps create the seal when you insert your portafilter into the machine. The notches on the head allow for a precise positioning of the portafilter which is crucial to ensure a consistent extraction. In addition to allowing you to easily insert your portafilter, the group head is also responsible to maintain an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew basin, ensuring that the temperature is constant for extraction. It is important to remember that even a slight deviation can make the difference between a decent and a great espresso. The Pump The motorized pumps that are used in rotary espresso machines provide the nine atmospheric bars of pressure required to extract espresso. This is different from manual piston machines which use a lever. The pressure is built by pumping water through a heat exchanger and then through the ground coffee. Pumps are typically less expensive than piston-driven machines, and tend to last longer. However, both types of machines could degrade with overuse and insufficient cleaning. best espresso machine add mechanical complexity and can lead to the cost of even the simplest models. Certain espresso machines utilize steam pressure instead of a pump for brewing espresso. This can cause over-extraction because the boiler that makes steam also heats the water to boil. These machines also have to constantly rebuild their pressure in between cups. This takes energy and time. Many espresso machines employ a vibration or rotary pump, which has a vibration model using a rotating disc that generates the pressure and a rotary model pushing hot water through the grounds under high speed. Both machines can make great espresso, but rotary machines are more quiet, durable and less likely to break down. The Boiler The boiler is the one that is used to heat the water to the ideal temperature for extraction. The steam that is produced reaches the portafilter that contains ground espresso beans and is then pumped into the cup. The steam creates pressure to push through the coffee grounds. This creates a layer crema that is then poured over. This is one of the main characteristics of a good espresso. There are three kinds of espresso makers. They differ in the kind of pump they use and how hot the coffee is. There are various ways to control the brew as well as the size of the cup that can be produced by the machine. The first espresso machines were steam-type. They utilized one boiler to make both steam and brew, but the pressure they could create was minimal – two bars of atmospheric pressure at the most. This led to the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese producers Luigi Bezzerra & Desiderio Pavoni. The most well-known espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp your beans yourself, but the pump regulates the flow of water and pressure. This is a great compromise between the human touch and the mechanized consistency. The Filter Espresso machines usually have a filter that separates the grounds of the coffee from hot water. The filter is also a vital component of the machine's temperature control, as it helps prevent overheating. It also improves flavor, as it allows for a more prolonged bloom time. This allows the beans to release their flavors and provides the chance for better extraction. However, it is important to keep in mind that even a good filter can produce a bad cup of coffee as the quality of the beans and extraction is important. It's in this area that the magic takes place. This is what makes espresso taste so good. The grouphead, often referred to as the brew head, is where the portafilter (the thing you put the ground coffee into) is placed when you're making espresso. In an espresso machine that is driven by steam, hot water is heated in an airtight tank to create steam. This is then pushed through the grounds with high pressure. These machines are less expensive and easier for the user to maintain than pumps-driven models. They are however limited for creating the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars. In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They use an air-compressor to force hot water into the ground and are more mobile than steam-driven electric espresso machines.