How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly is it that makes it work?
espresso machines for home is created by forcing hot water under high 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 you put in when making espresso. It is responsible for dispersing the water into the portafilter before controlling the pressure of the resulting extraction. There are several different types of group head each with its own advantages and drawbacks. Some focus on temperature stability, whereas others on pre-infusion capabilities, while others are designed to control the lever. Some come with a combination of both, such as the E61. This is a very popular choice for baristas as it provides a variety of benefits in a single package.
As you can see in the above photo the group head is made up of numerous notches that you can place your portafilter before twisting it by hand to secure it. There is also a rubber gasket which is located inside the notches to help create an airtight seal when you insert your portafilter into the machine. The notches on the head permit a precise positioning of the portafilter which is crucial for a consistent extraction.
The group head does not just allow you to put in your portafilter easily but also maintains the temperature at a constant level. It does this by cycling hot water through the brew container and around the portafilter, making sure that it is always at the right temperature for extraction. It is important to note that even a tiny deviation can make the difference between a good and a excellent espresso.
The Pump
In contrast to manual piston machines which rely on a lever that pressurize water, rotating espresso machines rely upon 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 typically more affordable and last longer than piston-driven machines. However, both types of machines are susceptible to degrading due to overuse and inadequate cleaning. Pumps are also more complicated mechanically, which could increase the cost of even simplest models.
Some espresso machines use steam pressure instead of a pump in order to brew espresso. This can result in over-extraction because the boiler that makes steam also heats the water to boil. These machines also have to continually rebuild their pressure between cups. This takes energy and time.
A large majority of espresso machines employ a rotary or vibration pump. A vibration model employs a rotating disk to generate pressure, whereas the circular model pushes hot liquid through the ground at a high speed. Both machines produce great espresso but rotary machines are more stable, quieter and less likely to break down.
The Boiler
The boiler is what heats the water to the ideal temperature for extraction. The steam produced gets to the portafilter which is the container that holds 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 results in a layer crema that is then poured over. This is a hallmark of a great espresso.
There are three types of
espresso makers, which differ in the type of pump they employ and the degree of heat that the brew is. There are a variety of ways to control the brew and the size of the cup that can be produced by the machine.
The first
Compact espresso machine machines were steam-types. The earliest espresso machines were steam types. The coffee tasted bitter and burned. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern
espresso coffee machines for sale machine.
The most common espresso machine is a semiautomatic model with an
electric espresso maker pump. When people think of
cheap espresso machine machines, they envision these machines. With a semi-automatic machine, you must grind the beans and tamp them by hand, but the pump is able to regulate the flow of water and pressure. This is an excellent compromise between human touch and the mechanized quality.
The Filter
Typically, espresso machines have filters to separate the coffee grounds as they pass through the hot water. The filter is also a vital component of the machine's temperature control, since it helps to prevent overheating.
It also aids in flavor as a filter allows for a more prolonged bloom phase. This lets the beans let their nuances out, and also allows for better extraction.
However it is crucial to remember that even a top filter could result in a bad cup of coffee as the quality of the beans and extraction are important.
It's in this area that the magic takes place. This is the reason why espresso tastes so good. The grouphead (also called the brewhead) is where you put the portafilter - the thingy which you put the grounds of your coffee into when making espresso.
In a steam-driven espresso machine hot water is heated in an airtight container to create steam. Steam then pushes the hot water through the grounds at high pressure. These kinds of machines are generally less expensive and simpler to maintain than pumps-driven models. However, they are limited in their ability to produce the ideal conditions for brewing as they only operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.
In recent years, espresso machines powered by compressed air-pump are becoming increasingly popular. They use an air-compressor to push hot water through the ground. They are also more mobile than steam-driven electric espresso machines.