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How Does Machine Espresso Work? The machine espresso makes use of precise pressure and filtering technology that is amazing to create the coffee you love. What exactly is it that makes it work? Espresso is created by forcing hot water under pressure through finely ground coffee. The process is similar to that of making drip coffee. However the pressure is the primary difference. The Group Head As the name suggests, the group head is where you insert your portafilter when brewing espresso. It disperses the water into the portafilter, and regulates the pressure of extraction. There are numerous kinds of group heads, each with its own advantages and drawbacks. Some are designed for the stability of temperature while some are built to handle pre-infusion. Others are made to control the lever. There are some that contain a variety of features, like the E61, which is the classic choice among many baristas due to its ability to provide multiple benefits in a single package. As you can see in the image above 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 from rubber which is located inside the notches to help create the seal when you insert your portafilter into the machine. The notches allow for an exact placement of the portafilter. This is vital for a consistent extraction. The group head not only lets the portafilter to be inserted easily however it also keeps the temperature at a constant level. This is done by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is always at the right level for extraction. This is important, as even a few degrees can be the difference between a good and great espresso. The Pump Contrary to manual piston machines which rely on a lever that pressurize water, rotary espresso machines rely on motorized pumps to provide the nine atmospheric bars of pressure necessary for espresso extraction. The pressure builds by removing tap water from a reservoir, and pumping it through a heat exchanger prior being shot through the ground coffee in the group head. Pumps are typically less expensive and last longer than piston-driven machines. However, both kinds of machines can degrade because of excessive use and poor cleaning. Pumps are also more complex mechanically, which could increase the cost of even simplest models. Some espresso machines use steam pressure instead of a pump for brewing espresso. This can result in over-extraction because the boiler that makes steam also heats the water until it comes to a boil. The machines must also constantly rebuild their pressure in between cups. This takes energy and time. A majority of espresso machines use the rotary or vibration pump, with a vibration model using a vibrating disc to create pressure and an rotary model that pushes hot water through the grounds at high speed. Both machines can produce excellent espresso, however rotary machines are more quiet, durable and less likely to fail. The Boiler The boiler makes the water warm to a temperature that is ideal to extract. The resulting steam is then transferred to the portafilter which holds the ground espresso coffee and is then pumped into the cup. The steam causes pressure to push through the grounds of the coffee. This creates a crema on top of the espresso. This is a sign of a great espresso. There are three different types of espresso machines, each with distinct pumps and brew temperature. There are various ways that the brew can be controlled, as well as the size of the cup that the machine can produce. The first espresso machines were steam type. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burnt. The modern espresso machine was invented by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni. The most well-known espresso machine is a semiautomatic one with an electric pump. These are the things people think of when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans on your own The pump, however, regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanised consistency. The Filter Typically, espresso machines use a filter to separate out the grounds of coffee as they move through the hot water. The filter is also an important component of the temperature control system because it stops the machine from overheating. Filters also aid in flavor, as it permits a longer flowering phase. This allows the beans to release their flavor and improves extraction. However it is crucial to keep in mind that even a top filter can make a terrible cup of coffee as the quality of the beans and extraction are important. It's here that the magic happens. machines espresso machines is the reason why espresso tastes so delicious. The grouphead (also called the brewhead) is where you put the portafilter – the thingy that you put the coffee grounds in, when making espresso. Steam-driven espresso machines use hot water that is heated inside an airtight container to make steam. The steam then pushes hot water through coffee grounds under high pressure. These kinds of machines are usually cheaper and easier to maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars. In recent times, espresso machines powered by compressed air-pump have become increasingly popular. They utilize an air compressor to push the hot water through the grounds and are significantly more portable than steam-driven electric machines.