The Main Problem With Machine Espresso And How You Can Fix It
How Does Machine Espresso Work?
Machine professional espresso maker employs precise pressure and amazing filter technology to make the perfect cup of coffee. How exactly does it work?
Espresso is created by forcing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee but the difference is in the pressure.
The Head of the Group
The group head is the portafilter you place in the espresso maker when making it. It disperses water into the portafilter, and then regulates the pressure of the extraction. There are a variety of types of group heads, each with their unique advantages and drawbacks. Some focus on temperature stability, others on pre-infusion features, and others are designed to control the lever. Some include a combination like the E61. This is a favorite among 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. You place your portafilter inside these notches, and then turn the head around to secure it. There is also a gasket made from rubber which is located inside the notches and helps create the 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.
In addition to allowing you easily insert your portafilter, the group head is responsible to ensure that the temperature remains even. This is accomplished by cycling hot water around the portafilter and through the brew basin, 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
Contrary to manual piston machines which rely on a lever to pressurize water, rotary cafe espresso machine machines rely on motorized pumps to supply the nine atmospheric bars of pressure that are required for espresso extraction. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee espresso machine.
Pumps tend to be less expensive than piston-driven machines, and tend to last longer. However, both types of machine can get damaged through overuse and lack of cleaning. They also add mechanical complexity and can lead to an expensive price for even the simplest models.
Some espresso machines remove the pump entirely and use steam pressure to brew espresso maker for home. This can cause over-extraction because the boiler that produces steam also causes the water to boil. These machines also have to constantly rebuild their pressure between cups. This takes energy and time.
A majority of espresso machines utilize an rotary or a vibration pump. A vibration model utilizes an oscillating disk to create pressure, whereas the rotary model pushes hot water through the ground at a rapid speed. Both types of machines can make a great espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is the one that heats the water to the right temperature for extraction. The steam that is produced reaches the portafilter, which holds the espresso grounds. It is then poured into the cup. During this process the steam causes enough pressure to push the grounds of the coffee through. This results in a whipped-up top of the espresso. This is one of the main characteristics of a great espresso.
There are three types of espresso makers. They differ in the type of pump they use and how hot the coffee is. There are many ways to control the brew as well as the size of cup that can be produced by the machine.
The first compact espresso machine machines were steam-types. They utilized a single boiler to make both brew and steam, but the pressure they could produce was very low - just two bars of atmospheric pressure maximum. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was designed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most well-known espresso maker is a semiautomatic machine with an electric pump. When people think of espresso machines, they picture these machines. If you have a semi-automatic machine you have to grind the beans and tamp them by hand. The pump is able to regulate the flow of water and pressure. This is a great solution that combines human control with mechanized consistency.
The Filter
Typically, espresso machines use a filter to separate out the coffee grounds as they pass through the hot water. The filter is also an essential part of the temperature control system since it helps prevent the machine from overheating.
A filter also improves flavor as it allows for an extended flowering time. This helps the beans to release their flavor and gives an opportunity for a better extraction.
However, it is important to keep in mind that even a great filter can result in a poor cup of coffee as the quality of the beans and extraction is essential.
This is where the magic happens, it's what makes an buy espresso machines really taste great. The grouphead, often called the brew head, is where the portafilter (the device you put the ground coffee into) is placed when making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to make steam. The steam then pushes hot water through grounds of the coffee under pressure. These types of machines are typically less expensive and easier to maintain than pump-driven models. They are however limited for creating the ideal brewing conditions 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 been gaining popularity. They utilize an air compressor to force hot water through grounds, and are far more portable than steam-driven electric machines.