How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and amazing filter technology to make the perfect cup of coffee. But how exactly does it work?
Espresso is made by pushing hot water at high pressure through finely ground coffee. The process is similar to making drip coffee. However it is the pressure that makes the main difference.
The Group Head
The group head is the portafilter that you insert when brewing espresso. It distributes water into the portafilter, and then regulates the pressure of the extraction. There are a variety of types of group heads each with its particular advantages and drawbacks. Some are designed to provide the stability of temperature while some are built to handle pre-infusion. Others are made to control the lever. Some include a combination like the E61. This is a popular choice among baristas as it provides a variety of advantages in one package.
As you can see in the image above the head of the group has a number of notches. You place your portafilter in these notches and then twist the head to secure it. A gasket made of rubber is positioned in the notches to create a seal as you insert your portafilter. The notches permit an exact placement of the portafilter. This is vital for a consistent extraction.
In addition to allowing you to effortlessly insert your portafilter the group head is responsible to ensure that the temperature remains even. espresso coffee machine Coffeee does this by circulating hot water through the brew container and around the portafilter to ensure that it is always at the right temperature for extraction. It is important to note that even a small differences can make the distinction between a decent and a excellent espresso.
The Pump
The motorized pumps that are used in espresso machines that rotate provide the nine atmospheric bars of pressure required for espresso extraction. This differs from manual piston machines which use a lever. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be less expensive and last for longer than piston-driven machines. However, both types of machines may degrade due to overuse and poor cleaning. They also add mechanical complexity which can result in a high price tag on even the most basic models.
Some espresso machines do away with the pump entirely and make use of steam pressure to make espresso. The drawback of this is that the boiler that produces steam also increases the temperature of water until it reaches boiling and can result in over-extraction. The machines must also constantly rebuild their pressure in between cups. This takes energy and time.
Many espresso machines use either a vibration or rotary pump. A vibration model employs a rotating disk to generate pressure, whereas a rotary model pushes hot water through the ground at a fast speed. Both machines can make great espresso but rotary machines are quieter, more durable and less likely to break.
The Boiler
The boiler is used to heat the water to the ideal temperature to extract. The steam produced gets to the portafilter which holds the espresso grounds. The steam is then channeled into the cup. During this process the steam causes enough pressure to push the grounds of coffee through. This creates a layer crema on top. This is one of the hallmarks of a good espresso.
There are three types of espresso machines, each with different pumps and brew temperature. There are many ways to control the amount of brew, as well as the size of cup that can be made by the machine.
The first espresso machines were steam type. The first espresso machines were steam-type machines. The coffee tasted bitter and burned. The modern espresso machine was invented by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso maker is a semi-automatic one with an electric pump. This is what people envision when they imagine an espresso machine. With a semi-automatic machine you need to grind the beans and then tamp them yourself but the pump provides regulated water flow and pressure. This is a perfect solution that combines human control with mechanized accuracy.
The Filter
Espresso machines typically use filters that separate the grounds of coffee from hot water. The filter is also an important element of the temperature control system since it helps prevent the machine from overheating.
It also improves flavor as a filter lets you enjoy a longer bloom phase. This lets the beans release their flavor and allows for better extraction.
However, it is important to keep in mind that even a top filter can produce a bad cup of coffee as the quality of the beans and extraction are vital.
This is where the magic happens, it's what makes an espresso really taste good. The grouphead (also called the brewhead) is where you put the portafilter, the thingy that you use to put the grounds of your coffee into while making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to produce steam. The steam then moves hot water through the coffee grounds under high pressure. These kinds of machines tend to be less expensive and simpler to maintain than pump-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 perfect shot requires 9-10 bars.
In recent years, espresso machines powered by compressed air-pump have become increasingly popular. They make use of an air compressor to push hot water through the ground and are more mobile than steam-driven electric espresso machines.