This Week's Most Remarkable Stories Concerning Machine Espresso How Does Machine Espresso Work?    Machine espresso utilizes precise pressure and incredible filter technology to produce the coffee we love. What exactly is it that makes it work?    Espresso is made by pushing hot water at 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 name implies the group head is the place you place your portafilter while brewing espresso. It is responsible for dispersing water into the portafilter before controlling the pressure that results from the extraction. There are many different kinds of group heads each with its particular advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion features, and others are designed to control the lever. Some have a combination, such as the E61. This is a very popular choice for baristas due to the fact that it has multiple advantages in a single package.    As you can see in the above photo the group head is fitted with several notches. The portafilter is placed in these notches and then twist the head to secure it. A rubber gasket is located in the notches to create a seal as you insert your portafilter. The notches allow for precise placement of your portafilter. This is vital for a consistent extraction.    The group head not only allows the portafilter to be inserted easily however, it also keeps an even temperature. This is accomplished by cycling hot water around the portafilter, and through the brew basin, ensuring that the temperature is at the right level for extraction. It is important to realize that even a few degree deviation can make the difference between a decent and a great espresso.    The Pump    Contrary to manual piston machines that use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to provide the nine atmospheric bars of pressure required for espresso extraction. The pressure is created by pumping water through a heat exchanger and then through the ground coffee.    Pumps tend to be less expensive than piston-driven machines and tend to last longer, however both types of machines could become damaged due to excessive use and poor cleaning. They also increase the complexity of mechanical systems that can lead to costly prices for even the simplest models.      Some espresso machines do away with the pump completely and instead use steam pressure to brew espresso. This can cause over-extraction because the boiler that makes steam also warms the water to boil. In addition the machines often have to restore their pressure between cups, which takes time and energy.    uk espresso machine of espresso machines utilize an rotary or a vibration pump. A vibration model makes use of an oscillating disk to create pressure, while a rotating model pushes hot water through the ground at a high speed. Both types of machine can make a great espresso, but the rotary models are quieter and more durable than vibration pumps.    The Boiler    The boiler is the part that heats water to an optimal temperature for extraction. The steam created is then directed to the portafilter, which is a container for espresso grounds. The steam is then channeled into the cup. During this process, steam creates pressure that pushes through the grounds of the coffee. This creates a layer crema that is then poured over. This is a hallmark of a great espresso.    There are three kinds of espresso makers, and they differ in the type of pump they use and how hot the espresso is. There are also different ways that the brew may be controlled and the dimensions of the cup the machine is capable of making.    The first espresso machines were steam types. They utilized one boiler to make steam and brew, however, the pressure they could produce was not very high - two bars of atmospheric pressure maximum. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.    The most popular espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans yourself however the pump controls the water flow and pressure. This is a great compromise between human control and mechanised reliability.    The Filter    Typically, espresso machines utilize a filter to separate out the grounds of coffee as they move through the hot water. The filter is also an essential element of the temperature control system as it prevents the machine from overheating.    It also enhances flavor as a filter allows for a longer bloom phase. This helps the beans release their nuances and gives an opportunity for a better extraction.    However it is crucial to remember that even a good filter can produce a bad cup of coffee, as the quality of the beans and extraction is still important.    This is where the magic happens. It's what makes espresso taste good. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy used to place the coffee grounds in, when making espresso.    Steam-driven espresso machines make use of hot water heated in an airtight vessel to create steam. The steam then pushes hot water through grounds of the coffee under pressure. These types of machines are usually less expensive and simpler to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing as they only 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 hot water into the grounds and are significantly more portable than steam-driven electric machines. 

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