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How Does Machine Espresso Work? Machine espresso employs precise pressure and mind-blowing filter technology to create the coffee we love. How exactly does it work? Espresso is made by pushing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee, but the key difference is in the pressure. The Group Head As the name suggests the group head is the place you place your portafilter when making espresso. It disperses water into the portafilter and regulates the pressure of extraction. There are numerous kinds of group heads each with distinct advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion features, and others are designed to control the lever. Some include a combination like the E61. This is a favorite among baristas because it offers multiple benefits in one package. As you can see in the image above the head of the group has a number of notches. You can place your portafilter into these notches and twist the head to lock it. There is also a rubber gasket that resides inside the notches, which helps create the seal when you insert your portafilter into the machine. The notches on the head permit an exact location of the portafilter which is necessary to ensure a consistent extraction. In addition to allowing you to effortlessly insert your portafilter the group head is also responsible for maintaining a consistent temperature. This is achieved by cycling hot water around the portafilter and through the brew-basket, ensuring that the temperature is always at the right level for extraction. It is important to note that even a slight differences can make the distinction between a good and excellent espresso. The Pump Unlike manual piston machines, which rely on a lever that pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure necessary for espresso extraction. This pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger prior it is shot through the ground coffee in the group head. Pumps tend to be less expensive than piston-driven machines, and tend to last longer. However, both types of machines may become damaged due to excessive use and poor cleaning. They also add mechanical complexity and can lead to the cost of even the simplest models. Some espresso machines eliminate the pump completely and make use of steam pressure to make espresso. The drawback of this is that the boiler that produces steam also raises the temperature of the water to the point of boiling, which can lead to over-extraction. They also have to continuously rebuild their pressure between cups. This requires energy and time. A large majority of espresso machines employ a rotary or vibration pump. A vibration model uses a vibrating disk to generate pressure, while the Rotary model pushes hot coffee through the ground at a fast speed. Both models can make a great espresso, however rotary machines are quieter and more durable than vibration pumps. The Boiler The boiler is what will heat the water to the ideal temperature to extract. The resulting steam is then transferred to the portafilter that contains the ground espresso and is then funneled down into the cup. The steam is able to create enough pressure to push the grounds of the coffee through. This creates a foam on the top of the espresso. This is a hallmark of a good espresso. There are three different types of espresso machines, each having distinct pumps and brew temperature. There are various ways that the brew can be controlled, as well as the dimensions of the cup the machine can make. The first espresso machines were steam-types. They had one boiler to make both brew and steam, however, the pressure they could create was minimal – two bars of atmospheric pressure at most. This resulted in the coffee tasting bitter and burnt. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine. The most popular espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they think of these machines. With a semi-automatic machine, you have to grind the beans and then tamp them by hand, but the pump is able to regulate the flow of water and pressure. This is a great compromise between the human touch and mechanized quality. The Filter Espresso machines usually use filters that separate the coffee grounds from the hot water. espresso machines uk Coffeee UK is also an essential element of the machine's temperature control, as it helps prevent overheating. A filter also helps with flavor because it allows for a longer flowering period. This lets the beans let their nuances out, and improves extraction. However it is crucial to remember that even a high-quality filter could result in a bad cup of coffee as the quality of the beans and extraction is crucial. It's here that the magic happens. This is the reason why espresso tastes so good. The grouphead, often referred to as the brewhead, is where the portafilter (the thing you put the coffee grounds into) sits when you're making espresso. In a steam-driven espresso machine, hot water is heated in an airtight container to produce steam, which is then pushed through the grounds at a high pressure. These types of machines are typically less expensive and simpler to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the ideal conditions for brewing since they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars. In recent years, espresso machines powered by compressed air-pump are becoming increasingly popular. They utilize an air compressor to force hot water through the grounds, and are far more portable than steam-driven electric machines.