How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to make the coffee we love. How 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, it is the pressure that makes the main difference.
The Head of the Group
The name implies, the group head is where you place your portafilter while brewing espresso. It disperses the water into the portafilter, and then controls the pressure of the extraction. There are many different kinds of group heads, each with their distinct advantages and drawbacks. Some are focused on temperature stability, others on pre-infusion capabilities, while others are designed to control the lever. Some have a combination, such as the E61. This is a favorite among baristas as it provides a variety of advantages in one package.
As you can see from the photo above the head of the group has a number of notches. It is possible to place your portafilter inside these notches, and then turn the head around to secure it. There is also a rubber gasket in the notches and helps create an airtight seal after inserting your portafilter into the machine. The notches on the head allow for an exact positioning of the portafilter which is essential for an efficient extraction.
Aside from allowing you to effortlessly insert your portafilter the group head is also responsible to ensure that the temperature remains even. This is done by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is constant to extract the coffee. It is crucial to keep in mind that even a small deviation can make the difference between a decent and a great espresso.
The Pump
The motorized pumps that are used in espresso machines rotary provide nine atmospheric bars of pressure required to extract espresso. This differs from manual piston machines that use a lever. This pressure is built up by pumping water through a heat exchanger and then through the ground coffee.
Pumps are typically less expensive and last longer than piston-driven machines. However, both types of machines can degrade because of excessive use and inadequate cleaning. They also make mechanically complex and can lead to a high price tag on even the most basic models.
Certain espresso machines eliminate the pump completely and use steam pressure to brew espresso. This can lead to over-extraction as the boiler that produces steam also heats the water until it comes to a boil. Additionally the machines often have to rebuild their pressure between cups, which takes time and energy.
Many espresso machines utilize an rotary or vibrating pump, with a vibration model that uses a vibrating disc to create pressure and the rotary model pushing hot water through the grounds under high speed. Both models are capable of producing excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is used to heat the water to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter which holds the ground espresso and gets funnelled down into the cup. The steam creates enough pressure to push the coffee grounds through. This results in a crema on the top of the espresso. This is a sign of a great espresso.
There are three kinds of espresso makers, and they differ in the kind of pump they use and how hot the espresso is. There are a variety of ways in which the brew could be controlled, as well as the dimensions of the cup the maker can create.
The earliest espresso machines were steam-based. The first espresso machines were steam types. The coffee tasted bitter and burnt. This is the reason why Milanese producers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most commonly used espresso maker is a semi-automatic device that has an electric pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp your beans yourself while the pump controls the flow of water and pressure. This is a great compromise between human control and mechanised consistency.
The Filter
Espresso machines typically use a filter that separates the grounds of coffee from hot water. best espresso machine uk is also a vital component of the machine's temp control, as it helps prevent overheating.
A filter also helps with flavor as it allows for the beans to flower for a longer period of time. This helps the beans to let their nuances out and provides an opportunity to improve extraction.
It is important to keep in mind that even the best 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 what makes espresso taste good. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy that you put the coffee grounds into, while making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight tank to produce steam, which is then pushed through the grounds at a high pressure. These kinds of machines are usually cheaper and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to create 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 make use of an air compressor to force hot water through the ground and are much more mobile than electric steam-driven espresso machines.