10 Facts About Machine Espresso That Make You Feel Instantly A Good Mood
10 Facts About Machine Espresso That Make You Feel Instantly A Good Mood
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How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and incredible filter technology to produce 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 but the major difference is in the pressure.
The Head of the Group
As the name implies the group head is where you place your portafilter while making espresso. It is responsible for dispersing water into the portafilter before controlling the pressure that results from the extraction. There are numerous kinds of group heads each with distinct advantages and drawbacks. Some focus on temperature stability, some on pre-infusion capabilities, and still others are designed to control the lever. Some come with a range of features, like the E61, which is considered the standard choice for many baristas for its ability to offer multiple perks in a single package.
As you can see from the above photo the head of the group is equipped with several notches. The portafilter is placed into these notches and twist the head to secure it. There is also a gasket made from rubber that is a part of the notches and helps to create a seal when you insert your portafilter into the machine. The notches allow for precise placement of the portafilter. This is essential for an accurate extraction.
The group head does not just allow you to insert your portafilter easily but also maintains an even temperature. It does this by circulating hot water through the brew container and around the portafilter, ensuring that it's always at the right temperature for extraction. This is crucial, since just a few degrees could mean the difference between excellent and great espresso.
The Pump
In contrast to manual piston machines which use a lever to pressurize water, the rotary espresso machines use motorized pumps to deliver the nine atmospheric bars of pressure necessary for espresso extraction. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be cheaper than piston-driven machines, and tend to last longer, however both types of machine can degrade with overuse and insufficient cleaning. Pumps are also more complex mechanically, which can raise the cost of even the simplest models.
Certain espresso machines remove the pump completely and instead utilize steam pressure to make espresso. The downside 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 also need to constantly rebuild their pressure in between cups. This takes energy and time.
A majority of espresso machines use the rotary or vibration pump, which has a vibration model using a vibrating disc that generates the pressure, and an rotary model that pushes hot water through the grounds under high speed. Both types of machine can make excellent espresso, but rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is the part which heats the water to the ideal temperature to extract. The steam produced gets to the portafilter which contains the espresso coffee grounds. The steam is then channeled into the cup. During this process the steam is able to create enough pressure to push the grounds of coffee through. This creates a layer crema that is then poured over. 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 different ways to control the strength of the brew and the size of the cup that can be produced by the machine.
The first espresso machines were steam types. They used one boiler to make both brew and steam, however, the pressure they could generate was low - only two bars of atmospheric pressure at the most. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic machine you need to grind the beans and then tamp them by hand, but the pump provides regulated water flow and pressure. This is a great compromise between the human touch and the mechanised quality.
The Filter
Typically, espresso machines employ a filter to separate out the grounds of the coffee as they go through the hot water. The filter is also a vital element of the machine's temperature control, since it stops overheating.
A filter also improves flavor because it allows for a longer flowering phase. This helps the beans to release their flavor and gives the chance for better extraction.
However it is crucial to keep in mind that even a top filter can result in a poor cup of coffee as the quality of the beans and extraction are crucial.
This is where the magic happens, and it's what makes an espresso really taste great. The grouphead (also called the brewhead) is where you place the portafilter, the thingy used to place the grounds of your coffee into when making espresso.
In a steam-driven espresso machine, espresso machine with milk frother hot water is heated in an airtight tank to produce steam, which then pushes the hot water through the grounds at high pressure. These kinds of machines are typically less expensive and simpler to maintain than pump-driven models. They are however limited for creating 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 years, compressed air-driven espresso machines have become more popular. They utilize an air compressor to push hot water through the ground and are more mobile than steam-driven electric espresso machines.