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How Does Machine Espresso Work? The machine espresso makes use of precise pressure and filtering technology that is amazing to make the coffee you enjoy. How exactly does it work? In order to make espresso hot water is forced under high 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 Head of the Group The group head is the portafilter that you put in when making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the resulting extraction. There are many different kinds of group heads each with its unique advantages and drawbacks. Some are designed to provide stability of temperature while others are specifically designed to handle pre-infusion. Others are made to control the lever. Some have a combination, like the E61. This is a preferred choice for baristas since it provides multiple benefits in a single package. As you can see in the photo above the group head is made up of several notches where you place your portafilter and twist it with your hands to lock it in. There is also a gasket made of rubber that resides inside the notches, which helps create an airtight seal when you insert your portafilter into the machine. The notches allow for precise placement of your portafilter. This is crucial for an even extraction. The group head is not just able to allow the portafilter to be inserted easily however, it also keeps a constant temperature. It does this by cycling hot water through the brew basket, and around the portafilter, making sure that it's always at the right temperature for extraction. This is important because just a few degrees could make the difference between a excellent and great espresso. The Pump Contrary to manual piston machines that use a lever to pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure that are required to extract espresso. The pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger prior to being pumped through the ground coffee inside the group head. Pumps tend to be less expensive than piston-driven models, and they tend to last longer, although both types of machines could get damaged through overuse and lack of cleaning. Pumps are also more complex mechanically, which can increase the cost of even the simpler models. Some espresso machines employ steam pressure instead of a pump in order to brew espresso. The disadvantage of this is that the same boiler that produces steam also raises the temperature of the water to the point of boiling which could lead to over-extraction. The machines must also continually rebuild their pressure between cups. This takes energy and time. Many espresso machines employ an rotary or vibrating pump, with a vibrating model using a vibrating disc to create the pressure and an rotary model that pushes hot water through the grounds under high speed. Both types of machines can make excellent espresso, but Rotary machines are quieter and more durable than vibration pumps. The Boiler The boiler is the component which heats the water to the optimal temperature for extraction. The resulting steam is then transferred to the portafilter containing ground espresso beans and is then funneled down into the cup. During this process, steam creates pressure to push through the coffee grounds. This creates a layer crema that is then poured over. This is the hallmark of a great espresso. There are three kinds of espresso makers, and they differ in the type of pump they use and the degree of heat that the coffee is. There are many ways to control the strength of the brew and the size of cup that can be made by the machine. coffee for espresso machine were steam-type. They used only one boiler to make both brew and steam, however the pressure they were able to generate was low – only two bars of atmospheric pressure, at most. This resulted in the coffee tasting burnt and bitter. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine. The most popular 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 by yourself however the pump controls the flow of water and pressure. This is an excellent compromise between human touch and the mechanised accuracy. The Filter Espresso machines typically use filters that separate the grounds of coffee from hot water. The filter is also a vital element of the temperature control system, because it stops the machine from overheating. It also aids in flavor, as a filter allows for a more prolonged bloom phase. This helps the beans let their nuances out and provides an opportunity to improve extraction. However, it is important to remember that even a great filter can result in a poor cup of coffee, since the quality of the beans and extraction is crucial. It's in this area that the magic happens. This is the reason why espresso tastes so delicious. The grouphead, also referred to as the brewhead, is where the portafilter (the thing you put the coffee grounds into) is placed when making espresso. Steam-driven espresso machines use hot water that is heated in an airtight container to make steam. The steam then pushes hot water through coffee grounds under high pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. However, they are limited 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 bar. In recent years, compressed-air-pump-driven espresso machines have been gaining popularity. They use an air-compressor to push hot water across the ground and are more mobile than steam-driven electric espresso machines.