How Does Machine Espresso Work?
Machine espresso employs precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. But how exactly does it work?
In order to make espresso hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.
The Group Head
The group head is the portafilter that is inserted when you are making espresso. It disperses water in the portafilter and regulates the pressure during the extraction. There are many different types of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, others on pre-infusion features, and others are designed to control the lever. Some include a combination like the E61. This is a preferred choice for baristas as it provides a variety of advantages in a single package.
As you can see in the above image the group head comes with several notches to place your portafilter before twisting it with your hands to secure it. A gasket made of rubber is positioned inside the notches to help create a seal when you insert your portafilter. The notches permit the precise placement of the portafilter. This is crucial to ensure a consistent extraction.
The group head not only lets you to put in your portafilter easily however, it also keeps an even temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, making sure the temperature is always right to extract the coffee. It is crucial to keep in mind that even a slight differences can make the distinction between a decent and a great espresso.
The Pump
In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure necessary for espresso extraction. This pressure is generated by pumping water through a heat exchanger and then through the ground coffee.
Pumps are generally less expensive than piston-driven machines, and tend to last longer, but both types of machine can become damaged due to excessive use and poor cleaning. Pumps are also more complicated mechanically, which can raise the cost of even simpler models.
Some espresso machines make use of steam more info pressure instead of a pump in order to brew espresso. This can cause over-extraction because the boiler that produces steam also heats the water to boil. Additionally these machines are often required to restore their pressure between cups, which takes time and energy.
A majority of espresso machines utilize an rotary or a vibration pump. A vibration model uses the vibrating disk to create pressure, while the Rotary model pushes hot coffee through the ground at high speed. Both machines can make excellent espresso, however rotary machines are more stable, quieter and less likely to break down.
The Boiler
The boiler makes the water warm to the right temperature for extraction. The resultant steam then reaches the portafilter which holds the ground espresso and is then pumped into the cup. The steam generates enough pressure to push the coffee grounds through. This results in a layer crema that is then poured over. This is one of the hallmarks of a great 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 various ways to control the 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 types. This resulted in the coffee tasting burnt and bitter. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most popular espresso maker is a semi-automatic one that has an electric pump. These are the images people have when they imagine an espresso machine. Semi-automatic machines here require you to grind and tamp the beans by yourself however the pump controls the flow of water and pressure. This is an excellent compromise between human touch and mechanized accuracy.
The Filter
Typically, espresso machines have a filter to separate out the grounds of the coffee as they go through the hot water. The filter is also an here essential component of the temperature control system, as it prevents the machine from overheating.
A filter can also help with flavor, as it permits an extended flowering time. This lets the beans release their flavors, and also allows for better extraction.
However it is crucial to keep in mind that even a top filter can result in a poor cup of coffee as the quality of the beans and extraction are crucial.
It's in this area that the magic occurs. This is the reason why espresso tastes so good. The grouphead, also called the brew head, is the place where more info the portafilter (the device you put the coffee grounds into) is placed 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 into the coffee grounds under high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. However, they are limited in their capacity to create the perfect conditions for brewing, as they only operate at more info 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.
In recent years, compressed air pump-driven espresso machines have become more popular. They use an air-compressor to push hot water across the ground and are more mobile than steam-driven electric espresso machines.