The 10 Most Scariest Things About Machine Espresso
The 10 Most Scariest Things About Machine Espresso
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How Does Machine Espresso Work?
Machine espresso utilizes precise pressure and incredible filter technology to produce the delicious coffee we enjoy. What 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 the main difference lies in the pressure.
The Group Head
The group head is the portafilter that you place in the espresso maker when making it. It disperses water into the portafilter, and regulates the pressure of extraction. There are a variety of types of group heads, each with their unique advantages and drawbacks. Some are focused on temperature stability, some on pre-infusion capabilities, and still others 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 has several notches to place your portafilter and twist it by hand to lock it in. There is also a rubber gasket that is a part of the notches to help create an airtight seal when you insert your portafilter into the machine. The notches on the head permit an exact positioning of the portafilter which is essential for an efficient extraction.
The group head not only lets you to insert your portafilter easily however it also keeps the temperature at a constant level. This is done by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is always at the right level to extract the coffee. This is important, as even a few degrees can make the difference between a good and great espresso.
The Pump
The motorized pumps used in espresso machines rotary provide nine atmospheric bar pressure that is required to extract espresso. This is different from manual piston machines that rely on a lever. The pressure is built by pumping water through a heat-exchanger and then through the ground coffee.
Pumps are typically less expensive and last for longer than piston-driven machines. However, both kinds of machines can degrade because of frequent use and poor cleaning. Pumps are also more complicated mechanically, which can raise the cost of even simpler models.
Certain espresso machines utilize steam pressure instead of a pump to brew espresso. This can result in over-extraction because the boiler that produces steam also heats the water until it comes to a boil. Additionally these machines are often required to restore their pressure between cups, which takes time and energy.
Many espresso machines make use of an rotary or vibrating pump, with a vibrating model using a rotating disc to generate the pressure and rotating models that push hot water through the grounds at high speed. Both machines produce great espresso, however rotary machines are more quiet, durable and less likely to fail.
The Boiler
The boiler is the element that heats water to the optimal temperature to extract. The resulting steam reaches the portafilter which holds the ground espresso and is then pumped down into the cup. The steam causes enough pressure to push the coffee grounds through. This produces a layer of crema on top. This is one of the hallmarks of a great espresso.
There are three distinct types of espresso machines, each having distinct pumps and brew temperature. There are a variety of ways to control the brew and the size of cup that can be made by the machine.
The first espresso machines were steam type. They employed a single boiler to make both brew and steam, however, the pressure they could produce was not very high - two bars of atmospheric pressure, at most. The coffee tasted bitter and burnt. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most well-known 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 machine, you grind the beans and tamp them yourself but the pump is able to regulate the flow of water and pressure. This is an excellent solution that combines human control with mechanised accuracy.
The Filter
Typically, espresso machines use filters to separate the grounds of coffee as they move through the hot water. The filter is also a crucial element 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 lets the beans release their flavor and also allows for better extraction.
It is important to remember that even the most efficient filter can result in a bad cup of coffee. The quality of the beans and the extraction process, remain crucial.
This is where the magic happens. It's what makes an espresso really taste great. The grouphead (also called the brewhead) is where you place the portafilter, the thingy that you use to put the grounds of your coffee into while making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight container to create steam, which is then pushed through the grounds at a high pressure. These kinds of machines are generally less expensive and simpler to maintain than pumps-driven models. They are however limited in their ability for creating the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The espresso machines home perfect shot requires 9-10 bars.
In recent years, compressed air-pump-driven espresso machines have been gaining popularity. They utilize an air compressor to force hot water through the ground and are more mobile than steam-driven electric espresso machines.