10 Things That Your Family Taught You About Machine Espresso
How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to make the coffee we love. What exactly is it?
Espresso is created by forcing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee, however the main difference lies in the pressure.
The Head of the Group
As the name suggests, the group head is where you insert your portafilter when brewing espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the extraction. There are numerous kinds of group heads, each with its own advantages and drawbacks. Some are focused on temperature stability, some on pre-infusion features, and others are designed to control the lever. Some include 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 in the above photo, the group head is equipped with several notches. You can place your portafilter inside these notches, and then twist the head to secure it. There is also a gasket made from rubber in the notches to help create a seal when you insert your portafilter into the machine. The notches permit an exact placement of the portafilter. This is crucial to ensure a consistent extraction.
Apart from allowing you easily connect your portafilter, the group head is responsible to ensure that the temperature remains even. This is achieved by cycling hot water around the portafilter and through the brew-basket to ensure the temperature is always right for extraction. It is important to remember that even a few degree variation can mean the difference between a good and a excellent espresso.
The Pump
Contrary to manual piston machines which rely on a lever to pressurize water, rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure necessary for espresso extraction. The pressure builds by removing tap water from a reservoir, and pumping it through a heat exchanger before being pushed through the ground coffee inside the group head.
Pumps are typically less expensive than piston-driven machines and tend to last longer, but both types of machines can become damaged due to excessive use and poor cleaning. They also add mechanical complexity that can lead to a high price tag on even the simplest models.
Some espresso machines remove the pump entirely and utilize steam pressure to make best cheap espresso machine. The drawback of this is that the boiler that produces steam also increases the temperature of the water to the point of boiling which could lead to over-extraction. In addition these machines typically have to restore their pressure between cups, which requires time and energy.
Many espresso machines utilize the rotary or vibration pump, which is a vibration model using a vibrating disc to generate the pressure and a rotary model pushing hot water through the grounds under high speed. Both types of machines can produce an excellent espresso capsule machine, but the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler will heat the water to the perfect temperature for extraction. The steam that is created reaches the portafilter, which contains the barista espresso coffee machine coffee espresso machine grounds. The steam is then channeled into the cup. In this process, the steam creates pressure that pushes through the coffee grounds. This results in a whipped-up top of the espresso. This is one of the hallmarks of a good espresso.
There are three kinds of espresso makers, and they differ in the type of pump they use and how hot the brew is. There are a variety of ways to control the strength of the brew and the size of cup that can be produced by the machine.
The first espresso machines were steam type. They utilized one boiler to make both steam and brew however, the pressure they could produce was very low - just two bars of atmospheric pressure maximum. The coffee tasted bitter and burned. This is why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most popular espresso maker is a semi-automatic machine that has an electric pump. When people think of espresso machines, they picture these machines. If you have a semi-automatic machine you need to grind the beans and then tamp them by hand, but the pump regulates the flow of water and pressure. This is an excellent combination of human control and mechanized reliability.
The Filter
Typically, espresso machines use a filter to separate out the coffee grounds as they pass through the hot water. The filter is also a vital part of the machine's temperature control, since it stops overheating.
A filter can also help with flavor as it allows for a longer flowering period. This allows beans to release their flavor and gives an opportunity to improve extraction.
It is important to keep in mind that even the finest filter could result in a poor cup of coffee. The quality of the beans and the extraction process, are still crucial.
It's here that the magic happens. This is what makes espresso taste so delicious. The grouphead (also called the brewhead) is where you put the portafilter, the thingy which you put the coffee grounds in, when making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. This then pushes the hot water through the grounds at a high pressure. These machines are cheaper and easier to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing since they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent years, compressed air-driven espresso machines have been gaining popularity. They utilize an air compressor to force hot water through grounds and are more portable than electric steam-driven machines.