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How Does Machine Espresso Work? The machine espresso uses precise pressure and filtering technology that is amazing to create the coffee you enjoy. But how exactly does it work? To make an espresso hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However it is the pressure that makes the main difference. The Group Head The group head is the portafilter you put in when making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the extraction. There are various kinds of group head each with its own advantages and disadvantages. Some are designed for the stability of temperature while some are built to handle pre-infusion. Some are designed to control the lever. There are even some that have a combination of features, such as the E61 that is to be the most popular among baristas for its ability to offer multiple perks in a single package. As you can see in the above photo the group head is made up of many notches in which you can place your portafilter and twist it manually to secure it. There is also a gasket made of rubber which is located inside the notches, which helps create an airtight seal when you insert your portafilter into the machine. The notches allow for the precise placement of the portafilter. This is vital for an accurate extraction. In addition to allowing you easily place your portafilter in, the group head is also responsible to ensure that the temperature remains even. It does this by circulating hot water through the brew basket, and around the portafilter to ensure that it's always at the correct temperature to extract. This is crucial, since even a small difference in temperature can be the difference between a good and excellent espresso. The Pump The motorized pumps that are used in rotary espresso machines provide the nine atmospheric bar pressure needed to extract espresso. This is different from manual piston machines that rely on levers. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee. Pumps are generally less expensive than piston-driven models, and they tend to last longer, although both types of machine can become damaged due to excessive use and poor cleaning. They also increase the complexity of mechanical systems which can result in a high price tag on even the simplest models. Some espresso machines remove the pump completely and instead employ steam pressure to create espresso. The downside is that the boiler that produces steam also increases the temperature of the water until it reaches boiling which can cause over-extraction. The machines must also continuously rebuild their pressure between cups. This takes energy and time. Many espresso machines utilize the rotary or vibration pump, with a vibration model using a rotating disc to generate the pressure and a rotary model pushing hot water through the grounds under high speed. Both machines can make excellent espresso, but rotary machines are quieter, more durable and less likely to fail. uk espresso machine is what will heat the water to the ideal temperature to extract. The steam produced is then directed to the portafilter, which holds the espresso grounds. It is then poured into the cup. The steam causes enough pressure to push the grounds of the coffee through. This creates a foam on top of the espresso. This is one of the main characteristics of a good espresso. There are three kinds of espresso machines, each having a different type of pump and brew temperature. There are a variety of 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 utilized one boiler to create both brew and steam, 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. This is why Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine. The most commonly used espresso maker is a semi-automatic device with an electric pump. This is what people envision when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans on your own, but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and mechanized accuracy. The Filter Espresso machines usually use filters that separate the grounds of the coffee from hot water. The filter is also an important element of the temperature control system, as it prevents the machine from overheating. A filter can also help with flavor, as it permits a longer flowering phase. 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, remain vital. It's in this area that the magic takes place. This is what makes espresso taste so good. The grouphead (also known as the brewhead) is where you place the portafilter, which is the thingy used to place the grounds of coffee into when making espresso. In a steam-driven espresso machine, hot water is heated in an airtight container to create steam. This is then pushed through the grounds under high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. They are however limited in their ability to create the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars. In recent years, compressed air-driven espresso machines have become more popular. They utilize an air compressor to push hot water through grounds and are significantly more portable than steam-driven electric machines.