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How Does Machine Espresso Work? The machine espresso is made using precision pressure, and a filtering technology that is amazing to create the coffee you enjoy. How exactly does it work? To make an espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, however the main difference lies in the pressure. The Head of the Group The group head is the portafilter that you insert when brewing espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the extraction. There are many different kinds of group head each with its unique advantages and drawbacks. Some focus on temperature stability, some on pre-infusion features, and others are designed to control the lever. There are even some that have a combination of features, like the E61, which is considered the most popular choice among baristas because of its ability to provide multiple benefits in a single package. As you can see in the picture above the head of the group is fitted with several notches. The portafilter is placed in these notches and then turn the head around to secure it. A rubber gasket is located in the notches to create a seal while you insert your portafilter. The notches on the head permit a precise location of the portafilter which is vital to ensure a consistent extraction. The group head is not just able to allow you to place your portafilter easily however, it also keeps an even temperature. It does this by cycling hot water through the brew container and around the portafilter, ensuring that it is always at the correct temperature to extract. This is important, as even a small difference in temperature can make the difference between good and great espresso. The Pump The motorized pumps in espresso machines rotary provide nine atmospheric bar pressure needed for espresso extraction. This differs from manual piston machines that use a lever. This pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pushed through the ground coffee in the group head. Pumps tend to be cheaper than piston-driven machines, and tend to last longer. However, both types of machine can be damaged by excessive use and inadequate cleaning. Pumps are also more complicated mechanically, which can raise the price of even the simple models. Some espresso machines can eliminate the pump completely and employ steam pressure to create espresso. The drawback of this is that the boiler that produces steam also raises the temperature of the water until it reaches boiling which can cause excessive extraction. These machines also have to constantly rebuild their pressure between cups. This requires energy and time. A majority of espresso machines utilize a rotary or vibration pump. A vibration model uses a vibrating disk to generate pressure, whereas the rotary model pushes hot water through the ground at a high speed. Both models can make excellent espresso, but rotary machines are quieter and more durable than vibration pumps. The Boiler The boiler is the component that heats water to the ideal temperature to extract. The steam created is then directed to the portafilter, which contains the espresso coffee grounds. It is then pumped into the cup. In this process, the steam creates pressure to push through the grounds of the coffee. This creates a layer crema on top. 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 also different ways that the brew can be controlled as well as the size of the cup the machine is capable of making. The first espresso machines were steam-types. They employed one boiler to make both brew and steam, but the pressure they could produce was very low – just two bars of atmospheric pressure at most. This led to the coffee tasting burnt and bitter. This is why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine. The most commonly used espresso maker is a semi-automatic device with an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic espresso machine, you must grind the beans and then tamp them by hand. The pump regulates the flow of water and pressure. This is a great compromise between the human touch and the mechanized consistency. The Filter Typically, espresso machines utilize filters that separate the grounds of coffee as they move through the hot water. The filter is also a vital component of the machine's temperature control, since it helps to prevent overheating. It also improves flavor, as a filter allows for a more prolonged bloom time. This helps the beans release their flavor and gives an opportunity for better extraction. It is important to remember that even the most efficient filter can make a bad cup of coffee. cafe espresso machine of the beans and the extraction process remain vital. It's in this area that the magic happens. This is the reason why espresso tastes so delicious. The grouphead (also known as the brewhead) is where you put the portafilter – the thingy which you put the grounds of your coffee into while making espresso. In the steam-driven espresso machine hot water is heated in an airtight container to create steam. This then pushes the hot water through the grounds at a high pressure. They are less expensive and are easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the ideal brewing conditions, since they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars. In recent years, compressed air-pump-driven espresso machines have become more popular. They use an air compressor to push hot water across the ground. They are also more mobile than electric steam-driven espresso machines.