How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and incredible filter technology to produce the coffee we love. What exactly does it work?
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 primary difference.
The Head of the Group
As the name suggests the group head is the place you put your portafilter in when brewing espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure of the resulting extraction. There are a variety of group heads each with distinct advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. Some include a combination such as the E61. This is a very popular choice for baristas due to the fact that it has multiple benefits in a single package.
As you can see in the above photo the group head is made up of several notches to put your portafilter, then twist it with your hands to lock it in. There is also a rubber gasket that resides inside the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches on the head permit an exact positioning of the portafilter which is essential to ensure an efficient extraction.
The group head is not just able to allow you to insert your portafilter easily, but it also maintains an even temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket, ensuring the temperature is always right to extract the coffee. It is important to note that even a slight deviation can make the difference between a decent and a great espresso.
The Pump
The motorized pumps used in espresso machines rotary provide nine atmospheric bars of pressure required for retro espresso machine extraction. This is different from manual piston machines which use levers. 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 longer than piston-driven machines. However, both types of machines are susceptible to degrading because of frequent use and insufficient cleaning. They also make mechanically complex which can result in an expensive price for even the simplest models.
Some espresso machines use steam pressure instead of a pump to make espresso. This could lead to over-extraction since the boiler that makes steam also heats the water to boil. In addition these machines typically have to restore their pressure between cups, which takes time and energy.
A majority of espresso machines use the rotary or vibration pump, with a vibration model that uses a vibrating disc to create the pressure and a rotary model pushing hot water through the grounds at high speed. Both machines can make 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 an ideal temperature to extract. The steam that is produced is then directed to the portafilter, which holds the espresso grounds. It is then pumped into the cup. During this process the steam causes enough pressure to push the coffee grounds through. This results in a layer crema on top. This is one of the main characteristics of a good espresso.
There are three kinds of espresso machines, each having a different type of pump and the temperature of the brew. There are various ways to control the brew and the size of cup that can be produced by the machine.
The first espresso machines were steam types. The first espresso machines were steam types. The coffee tasted bitter and burnt. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most commonly used espresso machine with grinder maker is a semi-automatic one with an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp your beans yourself however the pump controls the water flow and pressure. This is a great solution that combines human control with mechanised reliability.
The Filter
Espresso machines usually use filters that separate the grounds of the coffee from hot water. The filter is also an essential element of the machine's temperature control, as it helps prevent overheating.
It also helps with flavor, since a filter allows for a more prolonged bloom phase. This allows beans to release their nuances and gives an opportunity for a better extraction.
It is important to remember that even the finest filter can make a bad cup of best coffee espresso machine. The quality of the beans, and the extraction process, are still crucial.
This is where the magic happens, and it's what makes espresso taste great. The grouphead (also called the brewhead) is where you place the portafilter, which is the thingy which you put the grounds of your coffee into while making espresso.
In the steam-driven espresso machine hot water is heated in an airtight container to create steam. Steam then pushes the hot water through the grounds with high pressure. These machines are less expensive and are easier for the user 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 perfect shot requires 9-10 bars.
In recent years, espresso machines driven by compressed air-pump have become increasingly popular. They utilize an air compressor to force the hot water through the grounds and are significantly more portable than steam-driven electric machines.