How Does Machine Espresso Work?
The machine espresso makes use of precise pressure and filter technology that is mind-blowing to create the coffee you enjoy. How does it work exactly?
To make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the main difference.
The Group Head
The group head is the portafilter that you put in when making espresso. It disperses water into the portafilter, and then controls the pressure of the extraction. There are many different kinds of group head, each with their own advantages and drawbacks. Some are focused on temperature stability, whereas others on pre-infusion features, and others are designed to control the lever. Some have a combination of features, such as the E61 one, which is to be the most popular among baristas for its ability to offer multiple perks in one package.
As you can see in the above photo the group head comes with many notches in which you can place your portafilter and then twist it manually to lock it in. A gasket made of rubber is placed within the notches to create a seal as you insert your portafilter. The notches permit precise placement of the portafilter. This is crucial to ensure an efficient extraction.
The group head not only allows you to place your portafilter easily but also maintains the same temperature. 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 to extract. This is crucial, since even a small difference in temperature can be the difference between a excellent and great espresso.
The Pump
The motorized pumps in rotary espresso machines provide the nine atmospheric bars of pressure required to extract espresso. This differs from manual piston machines that use a lever. This pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger before it is shot through the ground coffee in the group head.
Pumps tend to be less expensive than piston-driven machines, and they tend to last longer, however both types of machine can become damaged due to excessive use and poor cleaning. They also add mechanical complexity and can lead to an expensive price for even the simplest models.
Some espresso machines employ steam pressure instead of a pump for brewing espresso. The drawback is that the same boiler that produces steam also increases the temperature of the water to the point of boiling, which can lead to excessive extraction. Additionally these machines are often required to rebuild their pressure between cups, which requires time and energy.
Many espresso machines use the rotary or vibration pump. A vibration model makes use of the vibrating disk to create pressure, while the rotating model pushes hot water through the ground at a rapid speed. Both types of machine are capable of producing excellent espresso, however Rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is the component that heats the water to the ideal temperature for get more info extraction. The steam that is produced gets to the portafilter which contains the espresso coffee grounds. It is then funneled into the cup. The steam is able to create enough pressure to push the grounds of the coffee through. This results in a layer of crema that is then poured over. This is a hallmark of a good espresso.
There are three types of espresso makers, and they differ in the kind of pump they use and the degree of heat that the espresso is. There are various ways that the brew can be controlled, as well as the size of the cup that the machine can produce.
The first espresso machines were steam type. They had only one boiler to make both steam and brew, however, the pressure they could produce was not very high - two bars of atmospheric pressure at most. The coffee tasted bitter and burnt. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most commonly used espresso machine is a semiautomatic one with an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans yourself, but the pump regulates the water flow and pressure. This is a perfect solution that combines human control with mechanized accuracy.
The Filter
Typically, espresso machines utilize filters that separate the coffee grounds as they pass through the hot water. The filter is get more info also an important part of the temperature control system as it keeps the machine from overheating.
It also aids in flavor as a filter can allow for a longer bloom time. This lets the beans release their flavors, and allows for better extraction.
It is important to remember that even the finest filter could result in a more info poor cup of coffee. The quality of the beans and the extraction, are still crucial.
This is where the magic happens, it's the thing that makes espresso taste good. The grouphead, sometimes called the brew head, is the place where the portafilter (the device you put the coffee ground into) is placed when you're making espresso.
Steam-driven espresso machines use hot water that is heated inside an airtight vessel to create steam. The steam then pushes hot water through grounds of the coffee under pressure. They are less expensive and are easier get more info for the user to maintain than pumps-driven models. They are however limited in their ability to create the ideal conditions for brewing since they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.
In recent years, compressed air-driven espresso machines have become more popular. They use an air compressor to push the get more info hot water through the grounds and are much more portable than steam-driven electric machines.