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How Does Machine Espresso Work? Machine espresso uses precision pressure and mind-blowing filter technology to make the coffee we love. How exactly does it work? 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, the pressure is the main difference. italian espresso machines As the name implies the group head is where you place your portafilter while brewing espresso. It is responsible for dispersing water into the portafilter, and controlling the pressure of the extraction. There are many different types of group heads, each with its own advantages and drawbacks. Some are designed to provide stability of temperature while others are designed to handle pre-infusion. Some are designed to control the lever. Some include 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 above photo The group head features many notches in which you can put your portafilter, then twist it by hand to lock it in. There is also a gasket of rubber that is a part of the notches to help create the seal when you insert your portafilter into the machine. The notches permit an exact placement of the portafilter. This is vital for an efficient extraction. In addition to allowing you to easily connect your portafilter, the group head is responsible for maintaining a consistent temperature. This is achieved by cycling hot water around the portafilter and through the brew-basket, making sure that the temperature is always at the right level for extraction. This is important, as just a few degrees could make the difference between a good and great espresso. The Pump In contrast to manual piston machines which rely on a lever that pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure that are required for espresso extraction. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee. Pumps are typically less expensive and last longer than piston-driven machines. However, both types of machines can deteriorate due to excessive use and poor cleaning. Pumps are also more complex mechanically, and can add to the cost of even most basic models. Some espresso machines make use of steam pressure instead of a pump to brew espresso. This can lead to over-extraction as the boiler that produces steam also heats the water to boil. They also have to continually rebuild their pressure between cups. This takes energy and time. Many espresso machines employ either a rotary or vibration pump, which is a vibration model that uses a vibrating disc to create pressure and a rotary model pushing hot water through the grounds under high speed. Both models can make excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps. The Boiler The boiler is the part that heats the water to the optimal temperature for extraction. The steam produced reaches the portafilter, which holds the espresso grounds. It is then pumped into the cup. The steam creates pressure to push through the coffee grounds. This produces a layer of crema that is then poured over. This is one of the hallmarks of a good espresso. There are three kinds of espresso makers, which differ in the kind of pump they use and the degree of heat that the espresso is. There are a variety of ways that the brew can be controlled as well as the size of the cup that the maker can create. The first espresso machines were steam-types. The earliest espresso machines were steam types. This resulted in the coffee tasting burnt and bitter. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine. The most commonly used espresso maker is a semi-automatic one with an electric pump. This is what people envision when they think of an espresso maker. With a semi-automatic machine, you need to grind the beans and then tamp them by hand, but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanized accuracy. The Filter Typically, espresso machines have filters to separate the grounds of coffee as they move through the hot water. The filter is also an important component of the temperature control system, since it helps prevent the machine from overheating. A filter also improves flavor because it allows for a longer flowering phase. This lets the beans release their flavor and improves extraction. It is important to keep in mind that even the most efficient filter can make a bad cup of coffee. The quality of the beans, and the extraction process are still very important. This is where the magic happens, it's the thing that makes espresso taste great. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy used to place the grounds of coffee into while making espresso. In a steam-driven espresso machine, hot water is heated in an airtight container to produce steam, which is then pushed through the grounds at a high pressure. These kinds of machines are usually cheaper and easier to maintain than pumps-driven models. They are however limited to create the perfect conditions for brewing since they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars. In recent years, compressed air-pump-driven espresso machines have become more popular. They utilize an air compressor to force hot water through grounds and are more portable than electric steam-driven machines.