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How Does Machine Espresso Work? Machine espresso utilizes precise pressure and mind-blowing filter technology to create the coffee we love. What exactly does it work? Espresso is created by forcing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee. However it is the pressure that makes the main difference. The Group Head The group head is the portafilter you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter and then controlling the pressure of the extraction. There are a variety of types of group heads each with its unique advantages and disadvantages. Some are focused on temperature stability, while others on pre-infusion options, and others are designed to control the lever. Some come with a range of features, such as the E61, which is considered the standard choice for many baristas due to its ability to provide multiple benefits in one package. As you can see in the image above the group head comes with several notches where you place your portafilter and then twist it manually to lock it in. There is also a rubber gasket in the notches to help create the seal when you insert your portafilter into the machine. The notches permit the precise placement of the portafilter. This is essential for an efficient extraction. The group head not only lets you to place your portafilter easily but also maintains the temperature at a constant level. It does this by circulating hot water through the brew container and around the portafilter, ensuring that it's always at the right temperature for extraction. This is crucial, since even a few degrees can mean the difference between excellent and great espresso. The Pump The motorized pumps in espresso machines rotary provide nine atmospheric bars of pressure required to extract espresso. This is different from manual piston machines that rely on a lever. The pressure is created by removing tap water from a reservoir, and pumping it through a heat exchanger prior being pushed through the ground coffee inside the group head. Pumps are typically less expensive than piston-driven machines, and they tend to last longer, however both types of machines could be damaged by excessive use and inadequate cleaning. They also make mechanically complex which can result in an expensive price for even the most basic models. Some espresso machines do away with the pump completely and utilize steam pressure to make espresso. The drawback of this is that the boiler that produces steam also raises the temperature of water until it reaches boiling which could lead to over-extraction. Additionally, these machines frequently have to restore their pressure between cups, which requires time and energy. Many espresso machines utilize a vibration or rotary pump, which is a vibration model using a vibrating disc to generate the pressure, and the 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 break. The Boiler The boiler is the component that heats water to the optimal temperature for extraction. The steam that is produced reaches the portafilter which holds the ground espresso and is then pumped down into the cup. The steam generates enough pressure to push the grounds of coffee through. This creates a crema on top of the espresso. This is the hallmark of a good espresso. There are three types of espresso machines, each with a different type of pump and the temperature of the brew. There are different ways in which the brew can be controlled, as well as the dimensions of the cup the maker can create. espresso machines for home were steam-types. They had a single boiler to make steam and brew, however the pressure they were able to create was minimal – two bars of atmospheric pressure maximum. The coffee tasted bitter and burnt. The modern espresso machine was invented by the Milanese makers Luigi Bezzerra & Desiderio Pavoni. The most common espresso maker is a semi-automatic one that has an electric pump. This is what people envision when they think of an espresso machine. With a semi-automatic machine you grind the beans and then tamp them by hand, but the pump controls the flow of water and pressure. This is a great compromise between the human touch and mechanized consistency. The Filter Typically, espresso machines use filters to separate the grounds of coffee as they move through the hot water. The filter is also an essential part of the machine's temperature control, as it prevents overheating. It also enhances flavor, as a filter can allow for a longer bloom time. This lets the beans release their nuances, and allows for better extraction. It is important to keep in mind that even the finest filter can make a bad cup of coffee. The quality of the beans, as well as the extraction, remain vital. It's in this area that the magic happens. This is what makes espresso taste so delicious. The grouphead (also known as the brewhead) is where you put the portafilter, the device that you put the coffee grounds in, when making espresso. In an espresso machine that is driven by steam, hot water is heated in an airtight container to create steam. Steam is then pushed through the grounds with 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 create the ideal brewing conditions, since they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars. In recent years, espresso machines driven by compressed air-pump have become increasingly popular. They utilize an air compressor to push hot water through grounds and are much more portable than electric steam-driven machines.