How Does Machine Espresso Work?
The machine espresso utilizes precise pressure and filter technology that is mind-blowing to create the coffee you love. What exactly is it?
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 the pressure is the primary difference.
portable espresso maker of the Group
The group head is the portafilter that you put in when making espresso. It distributes water into the portafilter, and then regulates the pressure of extraction. There are various kinds of group heads, each with their unique advantages and disadvantages. Some focus on temperature stability, while others on pre-infusion features, and others are designed to control the lever. There are some that contain a variety of features, like the E61 one, which is the classic choice among many baristas due to its ability to provide multiple benefits in a single package.
As you can see in the image above the head of the group is equipped with several notches. You can place your portafilter inside these notches, and then twist the head to secure it. There is also a gasket made from rubber in the notches to help create a seal when you insert your portafilter into the machine. The notches on the head allow for an exact positioning of the portafilter which is necessary to ensure an even extraction.
The group head not only lets you to place your portafilter easily but also maintains the same temperature. It does this by circulating hot water through the brew pan and around the portafilter, ensuring that it's always at the right temperature to extract. It is important to remember that even a tiny variation can mean the difference between a decent and a excellent espresso.
The Pump
Motorized pumps in espresso machines that rotate provide the nine atmospheric bar pressure required to extract espresso. This is different from manual piston machines that use a lever. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.
Pumps are generally less expensive and last for longer than piston-driven machines. However, both kinds of machines can deteriorate because of excessive use and inadequate cleaning. They also increase the complexity of mechanical systems which can result in an expensive price for even the most basic models.
Certain espresso machines do away with the pump entirely and employ steam pressure to create espresso. The drawback is that the same boiler that produces steam also increases the temperature of water until it reaches boiling which can cause excessive extraction. In addition, these machines frequently have to restore their pressure between cups, which requires time and energy.
Many espresso machines employ an rotary or vibrating pump, with a vibrating model that uses a vibrating disc to create pressure, and an rotary model that pushes hot water through the grounds at high speed. Both machines can produce excellent espresso, however rotary machines are more stable, quieter and less likely to break down.
The Boiler
The boiler is the element that heats water to an optimal temperature to extract. The resulting steam is then transferred to the portafilter which holds the ground espresso coffee, and is then pumped down into the cup. The steam creates enough pressure to push the grounds of coffee through. This produces a layer of crema on top. This is one of the main characteristics of a great espresso.
There are three distinct types of espresso machines, each having 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 size of the cup that the machine can produce.
The earliest espresso machines were steam-based. They used a single boiler to make steam and brew, but the pressure they could produce was very low - just two bars of atmospheric pressure at the most. This resulted in the coffee tasting burnt and bitter. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most well-known espresso maker is a semi-automatic device with an electric pump. When people think of espresso machines, they think of these machines. With a semi-automatic espresso machine, you must grind the beans and then tamp them by hand, but the pump controls the flow of water and pressure. This is an excellent compromise between human touch and mechanized consistency.
The Filter
Espresso machines usually use a filter that separates the grounds of coffee from hot water. The filter is also a vital part of the machine's temperature control, as it prevents overheating.
It also aids in flavor as a filter can allow for a longer bloom time. This allows the beans to release their nuances and gives an opportunity for a better extraction.
However it is crucial to keep in mind that even a top filter could result in a bad cup of coffee, because the quality of the beans and extraction are important.
It's here that the magic takes place. This is the reason why espresso tastes so delicious. The grouphead (also called the brewhead) is where you put the portafilter - the thingy used to place the coffee grounds into, while making espresso.
Steam-driven espresso machines make use of hot water that is heated in an airtight vessel to create steam. The steam then pushes hot water through coffee grounds under high pressure. These types of machines are typically less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the ideal conditions for brewing as they only operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars.
In recent years, compressed-air-pump-driven espresso machines have been gaining popularity. They utilize an air compressor to force the hot water through the grounds and are significantly more portable than electric steam-driven machines.