How Does Machine Espresso Work?
Machine espresso utilizes precise pressure and amazing filter technology to make the delicious coffee we enjoy. What exactly does 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
As the name implies the group head is the place you insert your portafilter when making espresso. It disperses the water into the portafilter and regulates the pressure of extraction. There are a variety of types of group heads, each with their own advantages and drawbacks. Some are designed to provide the stability of temperature while some are designed to handle pre-infusion. Others are built to control the lever. Some contain a variety of features, such as the E61 that is to be the most popular among baristas for its ability to offer multiple benefits in a single package.
As you can see in the above photo The group head features numerous notches that you can place your portafilter and then twist it by hand to secure it. There is also a gasket made of rubber that is a part of the notches and helps create the seal when you insert your portafilter into the machine. The notches permit precise placement of your portafilter. This is crucial for an even extraction.
The group head not only lets you to insert your portafilter easily however, it also keeps the temperature at a constant level. This is achieved by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is always at the right level to extract the coffee. It is important to note that even a few degree deviation can make the difference between a good 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. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be less expensive and last for longer than piston-driven machines. However, both types of machines are susceptible to degrading because of excessive use and poor cleaning. They also increase the complexity of mechanical systems, which can result in a high price tag on even the simplest models.
Certain espresso machines can eliminate the pump completely and utilize steam pressure to make espresso. The disadvantage of this is that the boiler that produces steam also increases the temperature of water until it reaches boiling and can result in excessive extraction. In addition these machines are often required to restore their pressure between cups, which requires time and energy.
Many espresso machines make use of the rotary or vibration pump. A vibration model makes use of an oscillating disk to create pressure, while the circular model pushes hot liquid through the ground at high speed. Both machines can produce excellent espresso but rotary machines are more stable, quieter and less likely to fail.
The Boiler
The boiler is the element that heats water to an optimal temperature to extract. The steam that is produced gets to the portafilter which holds the espresso grounds. espresso machine small is then channeled into the cup. The steam creates enough pressure to push the grounds of coffee through. This creates a crema on top of the espresso. This is one of the main characteristics of a good espresso.
There are three kinds of espresso makers, which differ in the kind of pump they use and the degree of heat that the espresso is. There are different ways to control the amount of brew, as well as the size of cup that can be produced by the machine.
The first espresso machines were steam-type. The first espresso machines were steam-type machines. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso maker is a semi-automatic device that has an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic machine, you have to grind the beans and then tamp them yourself but the pump is able to regulate the flow of water and pressure. This is a great compromise between the human touch and mechanized consistency.
The Filter
Espresso machines usually use filters that separate the coffee grounds from the hot water. The filter is also a vital component of the temperature control system, because it stops the machine from overheating.
It also improves flavor, since a filter allows for a longer bloom time. This allows the beans to release their flavors and provides an opportunity for a better extraction.
However, it is important to remember that even a great filter could result in a bad cup of coffee as the quality of the beans and extraction is important.
This is where the magic happens, it's what makes espresso taste great. The grouphead (also called the brewhead) is where you place the portafilter, the thingy that you put the coffee grounds in, while making espresso.
Steam-driven espresso machines use hot water that is heated inside an airtight container to produce steam. The steam then moves hot water through the grounds of coffee under high pressure. These types of machines are usually cheaper and easier to maintain than pumps-driven models. However, they are limited in their ability to produce the perfect brewing conditions as they only operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.
In recent years, compressed air-pump-driven espresso machines have been gaining popularity. They use an air compressor to push hot water across the ground and are more mobile than electric steam-driven espresso machines.