9 Lessons Your Parents Teach You About Machine Espresso
How Does Machine Espresso Work?
Machine espresso employs precise pressure and amazing filter technology to make the perfect cup of coffee. What exactly does it work?
To make an espresso hot water is pushed under pressure through finely ground coffee. The process is similar to 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 put your portafilter in when making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure that results from the extraction. There are many different types of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. Some are a combination, like the E61. This is a very popular choice for baristas as it provides a variety of advantages in a single package.
As you can see in the above photo, the group head is fitted with a variety of notches. It is possible to place your portafilter in these notches, then turn the head around to secure it. There is also a gasket made of rubber which is located inside the notches and helps to 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 crucial for an efficient extraction.
Aside from allowing you to easily insert your portafilter, the group head is responsible to maintain an even temperature. It does this by circulating hot water through the brew container and around the portafilter, ensuring that it's always at the right temperature to extract. This is important, as even a small difference in temperature can make the difference between good and great espresso maker barista.
The Pump
Contrary to manual piston machines which rely on a lever that pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure needed for espresso extraction. The pressure is built by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be less expensive than piston-driven machines and tend to last longer. However, both types of machines may degrade with overuse and insufficient cleaning. Pumps are also more complex mechanically, and can add to the price of even the simplest models.
Certain espresso machines can eliminate the pump completely and instead utilize steam pressure to make espresso. The downside is that the boiler that produces steam also raises the temperature of the water to boiling and can result in excessive extraction. Additionally these machines typically have to restore their pressure between cups, which takes time and energy.
A majority of espresso machines use the rotary or vibration pump, with a vibrating model using a rotating disc to create the pressure, and the rotary model pushing hot water through the grounds under high speed. Both types of machines can produce an excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is the component that heats water to an ideal temperature for extraction. The steam produced reaches the portafilter, which is the container that holds the espresso coffee grounds. It is then pumped into the cup. During this process the steam generates enough pressure to push the coffee grounds through. This results in a crema on the top of the espresso. This is one of the hallmarks of a good espresso.
There are three kinds of espresso makers, which differ in the type of pump they use and the degree of heat that the espresso is. There are also different ways that the brew may be controlled and the size of the cup the maker can create.
The first espresso machines were steam-based. They had one boiler to make steam and brew, however the pressure they were able to create was minimal - two bars of atmospheric pressure at most. This resulted in the coffee tasting burnt and bitter. This is why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most common espresso maker is a semiautomatic machine with an electric pump. This is what people envision when they imagine an espresso machine. With a semi-automatic machine you have to grind the beans and then tamp them yourself but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and mechanized quality.
The Filter
cheap espresso machine machines usually use filters that separate the grounds of the coffee from hot water. The filter is also a vital component of the machine's temp control, as it helps prevent overheating.
A filter can also help with flavor as it allows for the beans to flower for a longer period of time. This helps the beans let their nuances out and provides an opportunity for better extraction.
However it is crucial to keep in mind that even a high-quality filter can result in a poor cup of coffee, since the quality of the beans and extraction is still essential.
This is where the magic happens, it's the thing that makes an espresso really taste great. The grouphead, sometimes called the brew head, is the place where the portafilter (the device you put the ground coffee in) sits when you're making discount espresso machines.
Steam-driven espresso machines make use of hot water heated in an airtight vessel to create steam. The steam then pushes hot water through grounds of the coffee under pressure. These kinds of machines are typically less expensive and simpler to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the perfect conditions for brewing, because they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.
In recent years, compressed air-pump-driven espresso machines have been gaining popularity. They use an air compressor to push hot water through the ground, and are more mobile than steam-driven electric espresso machines.