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How Does Machine Espresso Work? Machine espresso employs precise pressure and amazing filter technology to make the perfect cup of coffee. What exactly is it that makes it work? Espresso is made by pushing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee, however the main difference lies in the pressure. The Head of the Group The name implies the group head is the place you insert your portafilter when brewing espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the resulting extraction. There are a variety of types of group heads, each with their particular advantages and drawbacks. Some focus on temperature stability, whereas others on pre-infusion capabilities, and still others are designed to control the lever. Some come with a combination of both, such as the E61. This is a preferred choice for baristas because it offers multiple advantages in a single package. As you can see in the above image The group head features several notches where you put your portafilter, then twist it with your hands to secure it. A gasket made of rubber is placed within the notches to create a seal when you insert your portafilter. The notches permit the precise placement of the portafilter. This is vital for a consistent extraction. The group head is not just able to allow the portafilter to be inserted easily, but it also maintains the same temperature. It does this by circulating hot water through the brew basket, and around the portafilter, ensuring that it is always at the correct temperature to extract. It is important to realize that even a slight variation can mean the difference between a decent and a excellent espresso. The Pump The motorized pumps that are used in rotary espresso machines supply the nine atmospheric bar pressure required to extract espresso. This differs from manually operated piston machines that employ levers. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee. Pumps tend to be cheaper than piston-driven models, and they tend to last longer, however both types of machines can get damaged through overuse and lack of cleaning. Pumps are also more complex mechanically, and can add to prices of even simple models. Certain espresso machines eliminate the pump completely and utilize steam pressure to make espresso. This can result in over-extraction because the boiler that makes steam also warms the water to boil. The machines also need to continuously rebuild their pressure between cups. This requires energy and time. A large majority of espresso machines employ a rotary or vibration pump. A vibration model utilizes a rotating disk to generate pressure, while a rotating model pushes hot water through the ground at a fast speed. Both machines produce great espresso but rotary machines are quieter, more durable and less likely to break. The Boiler The boiler is the element that heats water to an ideal temperature to extract. The steam that is produced reaches the portafilter, which contains the ground espresso and is then pumped into the cup. The steam causes pressure to push through the grounds of the coffee. This results in a layer crema on top. This is one of the hallmarks of a good espresso. There are three kinds of espresso makers, which differ in the type of pump they use and the degree of heat that the espresso is. There are different ways to control the brew as well as the size of cup that can be produced by the machine. The first espresso machines were steam-types. The first espresso machines were steam-type machines. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni. The most well-known espresso maker is a semi-automatic machine that has an electric pump. When portable espresso machine think of espresso machines, they envision these machines. With a semi-automatic espresso machine, you need to grind the beans and tamp them by hand, but the pump provides regulated water flow and pressure. This is a great compromise between the human touch and the mechanised quality. 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 a vital part of the machine's temperature control, since it helps to prevent overheating. Filters also aid in flavor, as it permits an extended flowering time. This helps the beans to release their flavor and gives the chance for better extraction. It is important to keep in mind that even the most efficient filter could result in a poor cup of coffee. The quality of the beans and the extraction, are still very important. It's here that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead, sometimes referred to as the brewhead, is where the portafilter (the container you place the coffee ground into) is placed when making espresso. In an espresso machine that is driven by steam, hot water is heated in an airtight tank to produce steam, which is then pushed through the grounds at a high pressure. These kinds of machines tend to be less expensive and easier to maintain than pump-driven models. However, they are not as efficient in their ability to create the perfect brewing conditions since they are only operating at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars. In recent times, espresso machines powered by compressed air-pump have become increasingly popular. They use an air compressor to force hot water through the ground and are much more mobile than electric steam-driven espresso machines.