How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and incredible filter technology to produce the perfect cup of coffee. What exactly does it work?
Espresso is created by forcing hot water under pressure through finely-ground coffee. The process is similar to that of making drip coffee. However the pressure is the main difference.
The Head of the Group
The group head is the portafilter that you place in the espresso maker when making it. It disperses water into the portafilter, and then controls the pressure of the extraction. There are several different types of group heads, each with their distinct advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion capabilities, and still others are designed to control the lever. There are even some that have a combination of features, like the E61, which is considered the most popular choice among baristas because of its ability to offer multiple perks in a single package.
As you can see in the above image the group head comes with many notches in which you can put your portafilter, then twist it manually to lock it in. There is also a gasket made from rubber that is a part of the notches to help create the seal when you insert your portafilter into the machine. The notches permit an exact placement of the portafilter. This is crucial to ensure an accurate extraction.
Apart from allowing you effortlessly insert your portafilter the group head is responsible for maintaining an even temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket, making sure that the temperature is always at the right level to extract the coffee. It is important to note that even a tiny differences can make the distinction between a great and a excellent espresso.
The Pump
The motorized pumps used in rotary espresso machines provide the nine atmospheric bars of pressure required for espresso extraction. This differs from manual piston machines that rely on levers. top espresso machines is built by pumping water through a heat-exchanger and then through the ground coffee.
Pumps are generally less expensive than piston-driven models, and they tend to last longer, although both types of machines could get damaged through overuse and lack of cleaning. Pumps are also more complicated mechanically, which could increase the cost of even simple models.
Certain espresso machines utilize steam pressure instead of a pump to brew espresso. This can lead to over-extraction as the boiler that produces steam also heats the water to boil. In addition, these machines frequently have to restore their pressure between cups, which requires time and energy.
A majority of espresso machines utilize the rotary or vibration pump. A vibration model makes use of a vibrating disk to generate pressure, while the circular model pushes hot liquid through the ground at high speed. Both machines produce great espresso, but rotary machines are more quiet, durable and less likely to break down.
The Boiler
The boiler is the one that will heat the water to the ideal temperature for extraction. The steam that is created reaches the portafilter, which contains the espresso coffee grounds. It is then poured into the cup. In this process, the steam creates pressure that pushes through the grounds of the coffee. This produces a layer of crema that is then poured over. This is one of the hallmarks of a great espresso.
There are three kinds of espresso makers. They differ in the type of pump they use and how hot the brew is. There are different ways to control the brew as well as the size of cup that can be made by the machine.
The first espresso machines were steam-types. They had one boiler to create steam and brew, however, the pressure they could generate was low - only two bars of atmospheric pressure at the most. The coffee tasted bitter and burned. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso maker is a semi-automatic one that has an electric pump. When people think of espresso machines, they think of these machines. With a semi-automatic espresso machine, you need to grind the beans and then tamp them by hand. The pump provides regulated water flow and pressure. This is an excellent compromise between human touch and the mechanised quality.
The Filter
Espresso machines typically have filters that separate the grounds of the coffee from the hot water. The filter is also an essential element of the temperature control system because it stops the machine from overheating.
A filter also improves flavor since it allows for a longer flowering phase. This allows the beans to release their nuances and gives an opportunity for a better extraction.
It is important to keep in mind that even the most efficient filter can make a bad cup of coffee. The quality of the beans and the extraction process are still very important.
This is where the magic happens, it's the thing that makes an espresso really taste great. The grouphead (also known as the brewhead) is where you place the portafilter - the thingy which you put the grounds of your coffee into when making espresso.
Steam-driven espresso machines use hot water heated in an airtight vessel to create steam. The steam then pushes hot water through grounds of the coffee under pressure. These machines are cheaper and easier for the owner to maintain than pumps-driven models. However, they are limited in their ability to provide the perfect brewing conditions as they only operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.
In recent years, espresso machines powered by compressed air-pump have become increasingly popular. They utilize an air compressor to push hot water across the ground. They are also more mobile than electric steam-driven espresso machines.