How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. What exactly is it that makes it work?
To make an espresso hot water is forced 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
The name implies, the group head is where you insert your portafilter when brewing espresso. It disperses water into the portafilter and regulates the pressure during the extraction. There are a variety of types of group head each with its own advantages and disadvantages. Some focus on temperature stability, others on pre-infusion options, and others are designed to control the lever. Some have a combination, like the E61. This is a preferred choice for baristas as it provides a variety of advantages in one package.
As you can see in the image above, the group head has numerous notches that you can place your portafilter before twisting it by hand to secure it. A gasket made of rubber is positioned inside the notches to help make a seal when you insert your portafilter. The notches permit the precise placement of the portafilter. This is vital for a consistent extraction.
Apart from allowing you effortlessly insert your portafilter the group head is responsible for maintaining an even temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is always at the right level for extraction. It is important to realize that even a tiny variation can mean the difference between a good and great espresso.
The Pump
Motorized pumps in espresso machines that rotate provide the nine atmospheric bars of pressure required to extract espresso. This is different from manually operated piston machines that employ levers. This pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger before it is shot through the ground coffee inside the group head.
Pumps tend to be less expensive and last for longer than piston-driven machines. However, both kinds of machines can degrade because of frequent use and inadequate cleaning. They also make mechanically complex and can lead to costly prices for even the most basic models.
Certain espresso machines utilize steam pressure instead of a pump in order to brew espresso. This can cause click here over-extraction because the boiler that makes steam also causes the water to boil. In addition these machines are often required to restore their pressure between cups, which takes time and energy.
Many espresso machines use the rotary or vibration pump. A vibration model uses the vibrating disk to create pressure, whereas the Rotary model pushes hot coffee through the ground at a fast speed. Both types of machines are capable of producing excellent espresso, however Rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is the part that heats water to the ideal temperature for extraction. The resulting steam reaches the portafilter which holds the ground espresso coffee, and is then pumped down into the cup. During this process the steam generates enough pressure to push the grounds of the coffee through. This results in a whipped-up top of the espresso. This is a sign of a great espresso.
There are three kinds of espresso machines, each with different types of pumps and brew temperature. There are also different ways in which the brew could be controlled and the size of the cup the machine is capable of making.
The earliest espresso machines were steam type. The earliest espresso machines were steam types. The coffee tasted bitter and burnt. The modern espresso machine was designed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic espresso machine, you must grind the beans and tamp them by hand, but the pump controls the flow of water and pressure. This is an excellent compromise between human touch and the mechanised consistency.
The Filter
Espresso machines typically have filters that separate the coffee grounds from the hot water. The filter is also a vital element of the temperature control system, because it stops the machine from overheating.
A filter can also help with flavor, as it permits an extended flowering time. This lets the beans let their nuances out, and improves extraction.
It is important to keep in mind that even the most efficient filter can make a bad cup of coffee. The quality of the beans and the extraction process, are still very important.
It's in this area that the magic takes place. This is what makes espresso taste so good. The grouphead (also known as the brewhead) is where you place the portafilter - the thingy that you use to put the coffee grounds in, when making espresso.
Steam-driven espresso machines make use of hot water that is heated in an airtight container to produce steam. The steam then pushes hot water through the grounds of coffee under high pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They utilize an air compressor to push hot water across the ground and are much more mobile than steam-driven electric espresso machines.