How Does Machine Espresso Work?
The machine espresso utilizes precise pressure and filter technology that is mind-blowing to create the coffee you enjoy. How does it work exactly?
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 Head of the Group
The group head is the portafilter that is inserted when you are making espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the resulting extraction. There are several different types of group heads, each with their distinct advantages and disadvantages. Some focus on temperature stability, others on pre-infusion options, and others are designed to control the lever. Some come with a combination of both, like the E61. This is a preferred choice for baristas as it provides a variety of advantages in a single package.
As you can see in the image above, the group head has many notches in which you can place your portafilter before twisting it by hand to lock it in. A gasket made of rubber is placed within the notches to make a seal when you insert your portafilter. The notches allow for the precise placement of the portafilter. This is crucial for an accurate extraction.
The group head is not just able to allow you to put in your portafilter easily however it also keeps the temperature at a constant level. It does this by circulating hot water through the brew basket and around the portafilter, making sure that it's always at the right temperature for extraction. This is important because even a small difference in temperature can make the difference between a excellent and great espresso.
The Pump
The motorized pumps used in espresso machines rotary provide nine atmospheric bar pressure needed to extract espresso. This differs 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 tend to be cheaper and last longer than piston-driven machines. However, both types of machines are susceptible to degrading due to overuse and inadequate cleaning. Pumps are also more complex mechanically, which can raise the cost of even the simpler models.
Certain espresso machines utilize steam pressure instead of a pump to make espresso. The drawback of this is that the boiler that produces steam also raises the temperature of water to the point of boiling which could lead to excessive extraction. In addition these machines are often required to restore their pressure between cups, which requires time and energy.
Many espresso machines utilize either a rotary or vibration pump, with a vibration model using a rotating disc to create 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 that heats water to the optimal temperature for extraction. The resultant steam then reaches the portafilter that contains the ground espresso coffee and is then funneled down into the cup. The steam causes enough pressure to push the coffee grounds through. This creates a layer crema on top. This is a hallmark of a great espresso.
There are three kinds of espresso makers. They differ in the type of pump they use and the degree of heat that the coffee is. There read more are various ways in which the brew could be controlled, as well as the dimensions of the cup the machine can produce.
The first espresso machines were steam-types. They employed a single boiler to make both steam and brew but the pressure they could produce was not very high - two bars of atmospheric pressure, at most. The coffee tasted bitter and burned. The modern espresso machine was designed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most common espresso maker is a semiautomatic machine that has an electric pump. These are what people imagine when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the flow of water and pressure. This is a perfect solution that combines human control with mechanised reliability.
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 component of the machine's temperature control, as it prevents overheating.
A filter also improves flavor since it allows for a longer flowering phase. This allows the beans to release their flavors and provides the chance for better extraction.
However it is crucial to keep in mind that even a great filter could result in a bad cup of coffee, as the quality of the beans and extraction is still vital.
This is where the magic happens, and it's what makes espresso taste good. The grouphead, also referred to as the brewhead, is where the portafilter (the device you put the ground coffee in) sits when you're making espresso.
Steam-driven espresso machines make use of hot water that is heated in an airtight container to create steam. The steam then pushes hot water through grounds of coffee under high pressure. They are less expensive and are easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.
In recent years, compressed-air-pump-driven espresso machines have become more popular. They use an air compressor to force hot water through the ground. They are also more mobile than steam-driven electric espresso machines.