How Does Machine Espresso Work?
The machine espresso uses precise pressure, as well as a filtering technology that is amazing to create the coffee you enjoy. How exactly does it work?
Espresso is produced by pushing hot water at 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 Group Head
As the name implies, the group head is the place you put your portafilter in when making espresso. It distributes water into the portafilter, and then regulates the pressure of the extraction. There are several different types of group heads each with its distinct advantages and disadvantages. Some are designed for stability in temperature, while others are built to handle pre-infusion. Others are built to control the lever. Some include a combination like the E61. This is a favorite among baristas since it provides multiple advantages in one package.
As you can see in the image above the group head comes with numerous notches that you can put your portafilter, then twist it manually to lock it in. A gasket of rubber is situated inside the notches, which helps create a seal when you insert your portafilter. The notches on the head allow for an exact position of the portafilter which is vital to ensure a consistent 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. This is done by cycling hot water around the portafilter and through the brew-basket, ensuring that the temperature is at the right level to extract the coffee. This is crucial, since just a few degrees could mean the difference between excellent and great espresso.
The Pump
In contrast to manual piston machines that use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure needed to extract espresso. The pressure is created by removing tap water from a reservoir, and pumping it through a heat exchanger prior to being pumped through the ground coffee inside the group head.
espresso machine uk tend to be more affordable and last longer than piston-driven machines. However, both kinds of machines can deteriorate due to overuse and insufficient cleaning. They also make mechanically complex that can lead to costly prices for even the most basic models.
Certain espresso machines remove the pump entirely and use steam pressure to brew espresso. This can cause over-extraction because the boiler that produces steam also heats the water until it comes to a boil. Additionally the machines often have to rebuild their pressure between cups, which takes time and energy.
A majority of espresso machines utilize a rotary or vibration pump. A vibration model makes use of a rotating disk to generate pressure, whereas a rotating model pushes hot water through the ground at high speed. Both machines can make excellent espresso, but rotary machines are more quiet, durable and less likely to break.
The Boiler
The boiler is the one that heats the water to the perfect temperature to extract. The steam produced will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. The steam is then channeled into the cup. During this process, the steam creates pressure and pushes through the grounds of the coffee. This results in a crema on the top of the espresso. This is one of the main characteristics of a good espresso.
There are three distinct types of espresso machines, each having different types of pumps and brew temperature. There are different ways that the brew may be controlled, as well as the dimensions of the cup the maker can create.
The first espresso machines were steam-type. The first espresso machines were steam-type machines. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso machine is a semiautomatic with an electric pump. These are what people imagine when they think of an espresso machine. With a semi-automatic machine you must grind the beans and then tamp them by hand, but the pump regulates the flow of water and pressure. This is a great compromise between the human touch and mechanized accuracy.
The Filter
Typically, espresso machines use a filter to separate out the grounds of coffee as they move through the hot water. The filter is also a vital element of the machine's temperature control, as it prevents overheating.
It also aids in flavor, since a filter allows for a longer bloom phase. This allows the beans to release their nuances and gives an opportunity for a better extraction.
It is important to keep in mind that even the finest filter can produce a bad cup of coffee. The quality of the beans and the extraction process, are still crucial.
It's here that the magic happens. This is the reason why espresso tastes so good. The grouphead, sometimes called the brew head, is where the portafilter (the container you place the coffee grounds into) is placed when you're making espresso.
In the steam-driven espresso machine hot water is heated in an airtight tank to create steam, which is then pushed through the grounds with high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the ideal brewing conditions, as they only operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.
In recent years, compressed air pump-driven espresso machines have become more popular. They utilize an air compressor to force hot water into the ground and are more mobile than electric steam-driven espresso machines.