How To Explain Machine Espresso To A Five-Year-Old
How Does Machine Espresso Work?
The machine espresso utilizes precision pressure, and a filter technology that is awe-inspiring to create the coffee you love. What exactly is it that makes it work?
Espresso is produced by pushing hot water under pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the main difference.
The Head of the Group
As the name suggests, the group head is the place you place your portafilter when brewing espresso. It distributes water into the portafilter, and controls the pressure of the extraction. There are various kinds of group heads each with its distinct advantages and disadvantages. Some focus on temperature stability, some on pre-infusion capabilities, while others are designed to control the lever. Some come with a combination of both, like the E61. This is a preferred choice for baristas as it provides a variety of advantages in one package.
As you can see in the photo above The group head features many notches in which you can place your portafilter and then twist it by hand to secure it. There is also a gasket made of rubber that resides inside the notches, which helps create the seal when you insert your portafilter into the machine. The notches on the head permit an exact placement of the portafilter, which is essential for an efficient extraction.
Apart from allowing you easily connect your portafilter, the group head is also responsible for maintaining an even temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is at the right level for extraction. It is important to note that even a small variation can mean the difference between a great and a excellent espresso.
The Pump
The motorized pumps in espresso machines that rotate provide the nine atmospheric bar pressure needed to extract espresso. This differs from manual piston machines that use a lever. The pressure builds by drawing tap water from a reservoir and pumping it through a heat exchanger prior to being pumped through the ground coffee in the group head.
Pumps are generally less expensive and last for longer than piston-driven machines. However, both types of machines can deteriorate because of excessive use and insufficient cleaning. They also make mechanically complex, which can result in an expensive price for even the most basic models.
Some espresso machines employ steam pressure instead of a pump to make espresso. The downside is that the boiler that produces steam also raises the temperature of water to the point of boiling which could lead to excessive extraction. In addition the machines often have to restore their pressure between cups, which takes time and energy.
Many espresso machines make use of a vibration or rotary pump, with a vibration model using a vibrating disc to create the pressure and the rotary model pushing hot water through the grounds under high speed. Both machines can make excellent espresso but rotary machines are more quiet, durable and less likely to fail.
The Boiler
The boiler will heat the water to the perfect temperature to extract. The steam created reaches the portafilter, which holds the espresso grounds. It is then poured into the cup. During travel espresso maker causes enough pressure to push the grounds of coffee through. This creates a layer crema on top. This is one of the hallmarks of a great espresso.
There are three kinds of espresso machines, each with a different type of pump and brew temperature. There are different ways that the brew may be controlled as well as the size of the cup the machine can produce.
The first espresso machines were steam-type. They had a single boiler to make both steam and brew, but the pressure they could create was minimal - two bars of atmospheric pressure, at most. This resulted in the coffee tasting burnt and bitter. This is the reason why Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most commonly used espresso maker is a semiautomatic machine with an electric pump. These are the things people think of when they think of an espresso maker. With a semi-automatic machine, you grind the beans and tamp them by hand, but the pump provides regulated water flow and pressure. This is an excellent compromise between human touch and mechanized quality.
The Filter
Espresso machines typically use a filter that separates the grounds of the coffee from the hot water. The filter is also an essential component of the machine's temperature control, since it stops overheating.
A filter also improves flavor because it allows for an extended flowering time. This lets the beans let their nuances out, and allows for better extraction.
However it is crucial to remember that even a high-quality filter can produce a bad cup of coffee as the quality of the beans and extraction are essential.
It's in this area that the magic happens. This is the reason why espresso tastes so good. The grouphead (also known as the brewhead) is where you put the portafilter, the device which you put the grounds of coffee into when making espresso.
Steam-driven espresso machines use hot water that is heated in an airtight container to produce steam. The steam then pushes hot water through grounds of the coffee under pressure. They are less expensive and easier to maintain than pumps-driven models. However, they are limited in their ability to create the ideal conditions for brewing because they 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 make use of an air compressor to force hot water into the ground and are more mobile than electric steam-driven espresso machines.
