How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to create the perfect cup of coffee. How exactly does it work?
In order to make espresso hot water is pushed under pressure through finely ground coffee machines espresso. The process is similar to that of making drip coffee. However, the pressure is the main difference.
The Group Head
The name implies the group head is the place you put your portafilter in when brewing espresso. It distributes water into the portafilter, and controls the pressure of the extraction. There are a variety of group heads, each with its own advantages and disadvantages. Some are designed to provide stability of temperature while others are specifically designed to handle pre-infusion. Some are designed to control the lever. Some include a combination like the E61. This is a favorite among baristas due to the fact that it has multiple benefits in one package.
As you can see in the image above, the group head is equipped with several notches. You place your portafilter inside these notches, and then twist the head to secure it. A rubber gasket is located inside the notches to help make a seal when you insert your portafilter. The notches on the head permit a precise location of the portafilter which is vital to ensure a consistent extraction.
In addition to allowing you easily connect your portafilter, the group head is responsible to maintain an even temperature. It does this by cycling hot water through the brew basket, and around the portafilter, ensuring that it is always at the right temperature for extraction. It is important to note that even a tiny variation can mean the difference between a good and a great espresso.
The Pump
In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure required for espresso extraction. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be less expensive than piston-driven machines, and they tend to last longer, however both types of machine can become damaged due to excessive use and poor cleaning. Pumps are also more complicated mechanically, which can increase the price of even the most basic models.
Certain home espresso machine machines eliminate the pump completely and use steam pressure to brew espresso. The downside is that the boiler that produces steam also increases the temperature of the water to boiling which could lead to over-extraction. They also have to continually rebuild their pressure between cups. This requires energy and time.
Many espresso maker machines make use of either a vibration or rotary pump. A vibration model makes use of a rotating disk to generate pressure, whereas a rotating model pushes hot water through the ground at high speed. Both machines can make excellent espresso, but rotary machines are more stable, quieter and less likely to break.
The Boiler
The boiler is the element which heats the water to the optimal temperature for extraction. The steam created reaches the portafilter, which contains the espresso coffee grounds. It is then pumped into the cup. The steam is able to create enough pressure to push the coffee grounds through. This results in a whipped-up the top of the espresso. This is a sign of a good espresso.
There are three types of espresso makers, and they differ in the type of pump they use and the degree of heat that the espresso is. There are a variety of ways to control the amount of brew, as well as the size of the cup that can be produced by the machine.
The earliest espresso machines were steam-based. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burned. This is why Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most popular espresso machine is a semiautomatic with an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp the beans on your own however the pump controls the water flow and pressure. This is a fantastic compromise between human control and mechanized reliability.
The Filter
Typically, espresso machines use filters that separate the grounds of coffee when they pass through the hot water. The filter is also a crucial component of the temperature control system, because it stops the machine from overheating.
It also improves flavor, as a filter allows for a longer bloom time. This allows the beans to let their nuances out, and allows for better extraction.
It is important to remember that even the best espresso machine under 200 filter can produce a bad cup of coffee. The quality of the beans, and the extraction process are still very important.
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 that you use to put the coffee grounds into, while making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to make steam. The steam then pushes hot water through the coffee grounds under high pressure. These kinds of machines tend to be cheaper and easier to maintain than pump-driven models. They are however limited for creating the ideal conditions for brewing, as they 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 use an air compressor to push the hot water through the grounds and are more portable than steam-driven electric machines.