How Does Machine Espresso Work?
The machine espresso uses precise pressure, as well as a filter technology that is mind-blowing to create the coffee you love. How exactly does it work?
To make an espresso, hot water is pushed under 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
As the name implies, the group head is the place you place your portafilter while making 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 their distinct advantages and drawbacks. Some focus on temperature stability, while others on pre-infusion options, and others are designed to control the lever. Some include a mix of features, such as the E61 one, which is to be the most popular among baristas due to its ability to provide multiple benefits in a single package.
As you can see from the image above, the group head has a number of notches. The portafilter is placed into these notches and twist the head to lock it. There is also a gasket of rubber in the notches, which helps create the seal when you insert your portafilter into the machine. The notches on the head permit an exact position of the portafilter which is vital to ensure an efficient extraction.
The group head not only allows you to insert your portafilter easily but also maintains the temperature at a constant level. It does this by circulating hot water through the brew pan and around the portafilter, ensuring that it's always at the right temperature for extraction. It is important to note that even a tiny deviation can make the difference between a good and a great espresso.
The Pump
In contrast to piston machines that are manually operated, which use a lever to pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure necessary to extract espresso. The pressure is built by pumping water through a heat exchanger and then through the ground coffee.
Pumps tend to be less expensive and last longer than piston-driven machines. However, both kinds of machines can deteriorate because of frequent use and insufficient cleaning. They also increase the complexity of mechanical systems that can lead to costly prices for even the most basic models.
Some espresso machines can eliminate the pump entirely and utilize steam pressure to make espresso. The drawback of this is that the same boiler that produces steam also raises the temperature of the water to the point of boiling which could lead to excessive extraction. They also have to constantly rebuild their pressure in between cups. This takes energy and time.
A large majority of espresso machines employ an rotary or a vibration pump. A vibration model employs a vibrating disk to generate pressure, whereas the Rotary model pushes hot coffee through the ground at a high speed. Both machines can make excellent espresso, but rotary machines are quieter, more durable and less likely to break down.
The Boiler
The boiler is what heats the water to the right temperature for extraction. The steam that is created reaches the portafilter, which holds the espresso grounds. It is then pumped into the cup. In this process, the steam creates pressure and pushes through the coffee grounds. This creates a foam on the top of the espresso. This is a hallmark of a good espresso.
There are three kinds of espresso makers, and they differ in the type of pump they employ and how hot the brew is. There are different ways to control the strength of the brew and the size of the cup that can be made by the machine.
The first espresso machines were steam types. They had one boiler to make both steam and brew however, the pressure they could produce was very low - just two bars of atmospheric pressure at most. The coffee tasted bitter and burned. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most well-known espresso machine is a semiautomatic model with an electric pump. These are what people imagine when they think of an espresso maker. With a semi-automatic espresso machine, you must grind the beans and then tamp them by hand, but the pump is able to regulate the flow of water and pressure. This is a perfect solution that combines human control with mechanized reliability.
The Filter
Espresso machines usually use filters that separate the coffee grounds from the hot water. The filter is also an essential part of the temperature control system, since it helps prevent the machine from overheating.
A filter also improves flavor as it allows for a longer flowering phase. This helps the beans to let their nuances out and provides an opportunity for a better extraction.
It is important to keep in mind that even the finest filter could result in a poor cup of coffee. The quality of the beans, as well as the extraction, are still crucial.
This is where coffee machines coffee the magic happens, and it's what makes an espresso really taste good. The grouphead (also known as the brewhead) is where you put the portafilter, which is the thingy that you use to put the grounds of your coffee into while making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight container to create steam. This then pushes the hot water through the grounds under high pressure. These kinds of machines tend to be less expensive and easier to maintain than pump-driven models. However, they are limited in their ability to create the perfect conditions for brewing, because they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.
In recent years, compressed air-driven espresso machines have been gaining popularity. They utilize an air compressor to push the hot water through the grounds and are more portable than electric steam-driven machines.