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How Does Machine Espresso Work? Machine espresso uses precision pressure and amazing filter technology to make the coffee we love. How exactly does it work? Espresso is made by forcing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee, however the main difference lies in the pressure. The Group Head The group head is the portafilter that you place in the espresso maker when making it. It is responsible for dispersing the water into the portafilter before controlling the pressure of the resulting extraction. There are a variety of types of group heads, each with their distinct advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion capabilities, and still others are designed to control the lever. Some include a combination such as the E61. This is a popular choice among baristas because it offers multiple advantages in one package. As you can see in the image above, the group head is equipped with several notches. You can place your portafilter into these notches and turn the head around to secure it. A gasket made of rubber is placed inside the notches, which helps create a seal when you insert your portafilter. The notches on the head permit an exact position of the portafilter which is necessary for a consistent extraction. In addition to allowing you to easily insert your portafilter, the group head is responsible to maintain an even temperature. It does this by cycling hot water through the brew basket and around the portafilter to ensure that it is always at the right temperature to extract. This is vital, because even a small difference in temperature can be the difference between a good and great espresso. bean to cup espresso machine in rotary espresso machines supply the nine atmospheric bar pressure needed for espresso extraction. This differs from manual piston machines that rely on levers. This pressure is built up by pumping water through a heat exchanger and then through the ground coffee. Pumps tend to be more affordable and last longer than piston-driven machines. However, both types of machines may degrade due to overuse and inadequate cleaning. Pumps are also more complicated mechanically, and can add to prices of even simpler models. Certain espresso machines utilize steam pressure instead of a pump to brew espresso. The disadvantage of this is that the same boiler that produces steam also increases the temperature of water to the point of boiling which can cause excessive extraction. In addition, these machines frequently have to rebuild their pressure between cups, which requires time and energy. A majority of espresso machines use a vibration or rotary pump, with a vibration model that uses a vibrating disc that generates the pressure, and a rotary model pushing hot water through the grounds at high speed. Both types of machines can make excellent espresso, however rotary machines are quieter and more durable than vibration pumps. The Boiler The boiler is the part that heats water to the ideal temperature to extract. The steam that is produced reaches the portafilter, which is a container for espresso grounds. It is then poured into the cup. The steam causes enough pressure to push the coffee grounds through. This results in a whipped-up the top of the espresso. This is one of the main characteristics of a great espresso. There are three types of espresso makers. They differ in the kind of pump they use and the degree of heat that the espresso is. There are various ways that the brew can be controlled and the size of the cup the machine is capable of making. The first espresso machines were steam-types. They had one boiler to make both steam and brew, but the pressure they could produce was very low – just two bars of atmospheric pressure maximum. This resulted in the coffee tasting bitter and burnt. This is why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine. The most popular espresso maker is a semi-automatic machine with an electric pump. These are what people imagine when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans on your own however the pump controls the water flow and pressure. This is an excellent compromise between human touch and the mechanized accuracy. The Filter Typically, espresso machines have filters that separate the grounds of coffee when they pass through the hot water. The filter is also an essential part of the temperature control system, since it helps prevent the machine from overheating. It also enhances flavor, since a filter can allow for a longer bloom time. This helps the beans release their flavors and provides an opportunity for better extraction. However it is crucial to keep in mind that even a good filter can make a terrible cup of coffee as the quality of the beans and extraction is essential. It's here that the magic takes place. This is the reason why espresso tastes so delicious. The grouphead (also called the brewhead) is where you place the portafilter, which is the thingy that you use to put the coffee grounds into, when making espresso. In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. This is then pushed through the grounds under high pressure. These kinds of machines tend to be less expensive and easier to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars. In recent times, espresso machines powered by compressed air-pump have become increasingly popular. They use an air-compressor to force hot water through the ground. They are also more mobile than steam-driven electric espresso machines.