How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the perfect cup of coffee. What exactly is it that makes it work?
Espresso is produced by pushing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee but the major difference is in the pressure.
The Head of the Group
The group head is the portafilter is inserted when you are making espresso. It is responsible for dispersing water into the portafilter before controlling the pressure that results from the extraction. There are numerous kinds of group heads each with their own advantages and drawbacks. Some are focused on temperature stability, whereas others on pre-infusion capabilities, while others are designed to control the lever. Some come with a range of features, such as the E61, which is to be the most popular among baristas due to its capacity to offer multiple perks in one package.
As you can see in the above photo, the group head is equipped with several notches. It is possible to place your portafilter in these notches, then twist the head to secure it. There is also a gasket made of rubber in the notches and helps create a seal when you insert your portafilter into the machine. The notches allow for an exact placement of the portafilter. This is essential for a consistent extraction.
The group head not only lets you to place your portafilter easily however, it also keeps the temperature at a constant level. It does this by circulating hot water through the brew basket, and around the portafilter, making sure that it is always at the correct temperature to extract. It is crucial to keep in mind that even a tiny difference 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 that provide the nine atmospheric bars of pressure required to extract espresso. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior it is shot through the ground coffee in the group head.
Pumps tend to be less expensive than piston-driven machines, and they tend to last longer, however both types of machines may get damaged through overuse and lack of cleaning. They also increase the complexity of mechanical systems, which can result in a high price tag on even the most basic models.
Some espresso machines can eliminate the pump completely and use steam pressure to brew espresso. The disadvantage of this is that the same boiler that produces steam also raises the temperature of water to boiling, which can lead website to excessive extraction. Additionally these machines are often required to rebuild their pressure between cups, which takes time and energy.
A majority of espresso machines use an rotary or vibrating pump, with a vibrating model using a vibrating disc that generates the pressure and an rotary model that pushes hot water through the grounds under high speed. Both types of machines can make a great espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is the component which heats the water to the ideal temperature for extraction. The resulting steam reaches the portafilter that contains ground espresso beans and is then pumped into the cup. In this process, the steam creates pressure to push through the coffee grounds. This results in a layer of crema on top. This is a sign of a good espresso.
There are three kinds of espresso makers. They differ in the type of pump they use and the degree of heat that the coffee is. There are many ways to control the brew as well as the size of the cup that can be produced by the machine.
The earliest espresso machines were steam type. The first espresso machines were steam types. This led to the coffee tasting burnt and bitter. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most well-known espresso maker is a semi-automatic machine with an electric pump. When people think of espresso machines, they think of these machines. If you have a semi-automatic machine you must grind the beans and tamp them yourself but the pump controls the flow of water and pressure. This is an excellent combination of human control and mechanized reliability.
The Filter
Typically, espresso machines have a filter to separate out the coffee grounds as they pass through the hot water. The filter is also a vital part of the temperature control system since it helps prevent the machine from overheating.
It also enhances flavor, as a filter can allow for a longer bloom time. This allows beans to release their nuances and gives the chance for better extraction.
However, it is important to keep in mind that even a good filter can produce a bad cup of coffee, because the quality of the beans and extraction are important.
It's in this area that the magic takes place. This is what makes espresso taste so good. The grouphead (also called the brewhead) is where you place the portafilter, which is the thingy that you put the coffee grounds into, while making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight container to create steam, which then pushes the hot water through the grounds at high pressure. These types of machines are usually less expensive and easier 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 perfect shot requires 9-10 bars.
In recent years, compressed air-driven espresso machines have become more popular. They make use of an air compressor to push hot water through the ground, and are more mobile than electric steam-driven espresso machines.