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 employs precise pressure and mind-blowing filter technology to create the perfect cup of coffee. How exactly does it work?
Espresso is produced by pushing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee but the major difference is in the pressure.
The Group Head
The group head is the portafilter you insert when brewing espresso. It disperses water into the portafilter and controls the pressure of the extraction. There are a variety of group heads each with their own advantages and drawbacks. Some are designed to provide the stability of temperature while some are designed to handle pre-infusion. Some 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 one package.
As you can see in the above photo the group head is fitted with a variety of notches. It is possible to place your portafilter inside these notches, and then twist the head to lock it. There is also a gasket of rubber that resides inside the notches and helps 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 efficient extraction.
The group head not only lets you to place your portafilter easily however, it also keeps an even temperature. This is accomplished by cycling hot water around the portafilter, and through the brew basin, ensuring the temperature is always right for extraction. This is crucial, since even a few degrees can make the difference between excellent and great espresso.
The Pump
The motorized pumps used in espresso machines that rotate provide the nine atmospheric bar pressure needed to extract espresso. This differs from manual piston machines which use levers. This pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger prior being shot through the ground coffee in the group head.
Pumps are generally less expensive than piston-driven machines, and tend to last longer. However, both types of machines may become damaged due to excessive use and poor cleaning. Pumps are also more complicated mechanically, which could increase prices of even simplest models.
Some espresso machines use steam pressure instead of a pump to make espresso. This can result in over-extraction because the boiler that produces steam also causes the water to boil. In addition, these machines frequently have to restore their pressure between cups, which takes time and energy.
Many espresso machines make use of either a rotary or vibration pump, which is a vibration model using a vibrating disc to create the pressure and rotating models that push hot water through the grounds under high speed. Both machines can produce excellent espresso but rotary machines are more quiet, durable and less likely to fail.
The Boiler
The boiler is what makes the water warm to the ideal temperature to extract. The steam produced is then directed to the portafilter, which holds the espresso grounds. The steam is then channeled into the cup. The steam generates enough pressure to push the grounds of the coffee through. This results in a whipped-up top of the espresso. This is a sign of a great espresso.
There are three types of espresso machines, each having distinct pumps and brew temperature. There are different ways that the brew can be controlled, as well as the size of the cup that the machine is capable of making.
The first espresso machines were steam type. They had a single boiler to make both brew and steam, but the pressure they could produce was not very high - two bars of atmospheric pressure maximum. The coffee tasted bitter and burnt. This is the reason Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most popular espresso machine is a semiautomatic model with an electric pump. These are the things people think of when they think of an espresso machine. If you have a semi-automatic machine you have to grind the beans and then tamp them by hand. The pump controls the flow of water and pressure. This is an excellent compromise between human touch and the mechanized accuracy.
The Filter
Typically, espresso machines have a filter to separate out the coffee grounds as they pass through the hot water. The filter is also a vital element of the temperature control system as it keeps the machine from overheating.
Filters also aid in flavor as it allows for a longer flowering phase. This helps the beans release their flavors and provides an opportunity for a better extraction.
However, it is important to keep in mind that even a top filter could result in a bad cup of coffee, as the quality of the beans and extraction is still crucial.
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 device that you use to put the coffee grounds in, when making espresso.
Steam-driven espresso machines make use of hot water that is heated inside an airtight vessel to create steam. The steam then moves hot water through the coffee grounds under high pressure. They are less expensive and easier for the owner to maintain than pumps-driven models. They are however limited in their ability to create 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, espresso machines driven by compressed air-pump are becoming increasingly popular. They use an air compressor to push the hot water through the grounds and are read more significantly more portable than steam-driven electric machines.