How Does Machine Espresso Work?
The machine espresso uses precise pressure, as well as a filter technology that is mind-blowing to create the coffee you love. What exactly is it that makes it work?
Espresso is produced by pushing hot water under high pressure through finely-ground coffee. The process is similar to that of making drip coffee. However, it is the pressure that makes the main difference.
The Head of the Group
The group head is the portafilter that you insert when brewing espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the extraction. There are numerous kinds of group heads, each with its own advantages and disadvantages. Some are designed for stability of temperature while others are designed to handle pre-infusion. Some are designed to control the lever. Some include a combination like the E61. This is a very popular choice for baristas as it provides a variety of advantages in a single package.
As you can see in the photo above the group head is made up of several notches where you place your portafilter and twist it with your hands to lock it in. A gasket of rubber is situated inside the notches to help create a seal when you insert your portafilter. The notches on the head permit a precise placement of the portafilter, which is crucial to ensure an efficient extraction.
Apart from allowing you easily place your portafilter in, the group head is responsible to ensure that the temperature remains even. It does this by circulating hot water through the brew basket and around the portafilter to ensure that it's always at the right temperature for extraction. This is vital, because just a few degrees could be the difference between a good and great espresso.
The Pump
Unlike manual piston machines, which rely on a lever to pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure necessary to extract espresso. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be cheaper than piston-driven machines, and tend to last longer, although both types of machines can get damaged through overuse and lack of cleaning. Pumps are also more complex mechanically, which can raise the price of even the simpler models.
Certain espresso machines espresso utilize steam pressure instead of a pump in order to brew buy espresso machine. This could lead to over-extraction since the boiler that produces steam also causes the water to boil. Additionally, these machines frequently have to restore their pressure between cups, which requires time and energy.
A majority of espresso machines utilize a rotary or vibration pump. A vibration model utilizes a vibrating disk to generate pressure, whereas a rotating model pushes hot water through the ground at a rapid speed. Both machines can make great espresso, but rotary machines are more quiet, durable and less likely to fail.
The Boiler
The boiler is the element that heats water to an optimal temperature to extract. The resulting steam is then transferred to the portafilter, which contains the ground espresso coffee and gets funnelled down into the cup. In this process, the steam creates pressure to push through the grounds of the coffee. This results in a layer crema on top. This is a hallmark of a great espresso.
There are three types of espresso machines, each with different pumps and the temperature of the brew. There are many ways to control the amount of brew, as well as the size of the cup that can be produced by the machine.
The first espresso machines were steam-type. The earliest espresso machines were steam-type machines. This led to the coffee tasting burnt and bitter. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.
The most common espresso maker is a semi-automatic device with an electric pump. When people think of espresso machines, espressomachines they imagine these machines. With a semi-automatic machine you must grind the beans and then tamp them yourself but the pump is able to regulate the flow of water and pressure. This is a great compromise between the human touch and the mechanised quality.
The Filter
Typically, espresso machines have a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also an essential component of the machine's temp control, since it stops overheating.
It also aids in flavor, as it lets you enjoy a longer bloom phase. This lets the beans let their nuances out, and allows for better extraction.
It is important to keep in mind that even the finest filter can result in a bad cup of coffee. The quality of the beans and the extraction, are still very important.
It's in this area that the magic occurs. This is what makes espresso taste so delicious. The grouphead, also called the brew head, is the place where the portafilter (the device you put the ground coffee in) sits when you're making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. This then pushes the hot water through the grounds at a high pressure. These types of machines are generally cheaper and easier to maintain than pump-driven models. However, they are not as efficient in their ability to produce the ideal conditions for brewing since they are only operating at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.
In recent years, compressed air pump-driven espresso coffee machine for home machines have become more popular. They utilize an air compressor to force hot water through the grounds and are significantly more portable than electric steam-driven machines.