How Does Machine Espresso Work?
Machine espresso utilizes precise pressure and amazing filter technology to make the coffee we love. But how exactly does it work?
Espresso is made by forcing hot water at high pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the primary difference.
The Head of the Group
As the name implies the group head is where you put your portafilter in when brewing espresso. It disperses water in the portafilter and regulates the pressure of extraction. There are numerous kinds of group heads each with its own 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 such as the E61. This is a popular choice among baristas as it provides a variety of benefits in one package.
As you can see in the picture above, the group head is fitted with a variety of notches. You can place your portafilter inside these notches, and then turn the head around to secure it. A rubber gasket is located in the notches to create a seal while you insert your portafilter. The notches allow for precise placement of the portafilter. This is vital for a consistent extraction.
In addition to allowing you to easily place your portafilter in, the group head is also responsible to maintain an even temperature. It does this by cycling hot water through the brew basket and around the portafilter, ensuring that it is always at the correct temperature for extraction. It is important to realize that even a few degree deviation can make the difference between a good and a great espresso.
The Pump
In contrast to manual piston machines which rely on a lever that pressurize water, Rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure that are required to extract espresso. The pressure is built 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 may get damaged through overuse and lack of cleaning. They also make mechanically complex and can lead to the cost of even the simplest models.
Some espresso machines employ steam pressure instead of a pump to make
best espresso maker. This can cause over-extraction because the boiler that makes steam also heats the water until it comes to a boil. They also have to constantly rebuild their pressure in between cups. This requires energy and time.
A majority of espresso machines use the rotary or vibration pump, which is a vibration model that uses a vibrating disc to create pressure, and a rotary model pushing hot water through the grounds at high speed. Both machines can make great espresso, but rotary machines are more stable, quieter and less likely to break down.
The Boiler
The boiler is the one that heats the water to the right temperature to extract. The resulting steam reaches the portafilter containing the ground espresso and is then pumped into the cup. During this process the steam generates enough pressure to push the grounds of the coffee through. This creates a crema on top of the espresso. This is one of the main characteristics of a great espresso.
There are three distinct types of espresso machines, each having different types of pumps and brew temperature. There are various ways to control the amount of brew, as well as the size of the cup that can be made by the machine.
The first espresso machines were steam-type. The earliest espresso machines were steam-type machines. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso maker is a semi-automatic one that has an electric pump. These are the images people have when they imagine an espresso machine. 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 combination of human control and mechanised accuracy.
The Filter
Espresso machines usually use filters that separate the grounds of the coffee from the hot water. The filter is also an essential element of the machine's temperature control, since it stops overheating.
A filter also improves flavor since it allows for an extended flowering time. This allows the beans to let their nuances out, and allows for better extraction.
However, it is important to remember that even a good filter can result in a poor cup of coffee, because the quality of the beans and extraction are crucial.
This is where the magic happens, and it's what makes an espresso really taste good. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy that you use to put the coffee grounds in, when making
espresso Maker barista.
In an espresso machine that is driven by steam, hot water is heated in an airtight container to create steam, which is then pushed through the grounds at high pressure. These machines are cheaper and easier to maintain than pumps-driven models. However, they are limited in their ability to provide the ideal brewing conditions, since they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.
In recent years, compressed air-driven espresso machines have become more popular. They utilize an air compressor to push hot water through the grounds and are significantly more portable than steam-driven electric machines.
