How Does Machine Espresso Work?
The machine espresso is made using precision pressure, and filter technology that is awe-inspiring to make the coffee you enjoy. How does it work exactly?
To make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the main difference.
The Head of the Group
The group head is the portafilter that is inserted when you are making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the extraction. There are a variety of group heads, each with its own advantages and disadvantages. Some focus on temperature stability, others on pre-infusion capabilities, while others are designed to control the lever. Some include a combination like the E61. This is a preferred choice for baristas as it provides a variety of advantages in a single package.
As you can see from the image above the head of the group is fitted with several notches. You can place your portafilter into these notches and twist the head to secure it. There is also a gasket of rubber in the notches, which helps create an airtight seal when you insert your portafilter into the machine. The notches on the head allow for a precise location of the portafilter which is vital for an efficient extraction.
In addition to allowing you easily connect your portafilter, the group head is responsible for maintaining an even temperature. This is done by cycling hot water around the portafilter, and through the brew-basket to ensure the temperature is always right for extraction. This is important, as even a small difference in temperature can make the difference between excellent and 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 necessary to extract espresso. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be less expensive and last longer than piston-driven machines. However, both kinds of machines may degrade due to overuse and poor cleaning. They also make mechanically complex, which can result in an expensive price for even the most basic models.
Some espresso machines do away with the pump completely and use steam pressure to brew espresso. This could lead to over-extraction since the boiler that makes steam also heats the water until it comes to a boil. In addition, these machines frequently have to restore their pressure between cups, which takes time and energy.
Many espresso machines use the rotary or vibration pump. A vibration model makes use of a vibrating disk to generate pressure, while the rotating model pushes hot water through the ground at a high speed. espresso coffee machine can produce excellent espresso but rotary machines are more quiet, durable and less likely to break.
The Boiler
The boiler is the component which heats the water to the ideal temperature for extraction. The steam produced reaches the portafilter, which is a container for espresso grounds. It is then poured into the cup. In this process, the steam causes pressure to push through the grounds of the coffee. This results in a layer of crema on top. This is one of the main characteristics of a good espresso.
There are three types of espresso makers. They differ in the type of pump they use and how hot the brew is. There are various ways in which the brew could be controlled as well as the size of the cup that the maker can create.
The first espresso machines were steam-types. The earliest espresso machines were steam types. This resulted in the coffee tasting bitter and burnt. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most popular espresso machine is a semiautomatic that has an electric pump. These are what people imagine when they think of an espresso machine. With a semi-automatic espresso machine, you grind the beans and tamp them by hand, but the pump controls the flow of water and pressure. This is a perfect compromise between human control and mechanized accuracy.
The Filter
Espresso machines usually have filters that separate the grounds of the coffee from the hot water. The filter is also an important element of the temperature control system, as it keeps the machine from overheating.
A filter also helps with flavor as it allows for a longer flowering phase. This lets the beans let their nuances out, and also allows for better extraction.
It is important to remember that even the best filter can make a bad cup of coffee. The quality of the beans, and the extraction, are still very important.
This is where the magic happens, it's the thing that makes an espresso really taste great. The grouphead (also called the brewhead) is where you put the portafilter, the device that you use to put the coffee grounds into, when making espresso.
Steam-driven espresso machines use hot water that is heated inside an airtight container to make steam. The steam then moves hot water through the coffee grounds under high pressure. They are less expensive and are easier for the user to maintain than pumps-driven models. However, they are limited in their ability to create the ideal conditions for brewing since they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.
In recent years, compressed-air-pump-driven espresso machines have become more popular. They make use of an air compressor to force hot water through the ground, and are more mobile than electric steam-driven espresso machines.