20 Trailblazers Setting The Standard In Machine Espresso
How Does Machine Espresso Work?
The machine espresso uses precise pressure, as well as a filtering system that is awe-inspiring to make the coffee you enjoy. What exactly is it?
To make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee, but the difference is in the pressure.
The Group Head
As the name implies the group head is the place you place your portafilter while making espresso. It is responsible for dispersing water into the portafilter, and controlling the pressure of the extraction. There are many different types of group heads each with distinct advantages and drawbacks. Some are designed to provide stability in temperature, while others are designed to handle pre-infusion. Some are designed to control the lever. There are also some that have a combination of features, such as the E61, which is the most popular choice among baristas for its ability to provide multiple benefits in one package.
As you can see in the image above, the group head has several notches where you place your portafilter and twist it manually to secure it. There is also a gasket of rubber that is a part of the notches and helps to create an airtight seal when you insert your portafilter into the machine. The notches on the head allow for a precise location of the portafilter which is vital to ensure an efficient extraction.
In addition to allowing you easily place your portafilter in, the group head is responsible to maintain an even temperature. It does this by circulating hot water through the brew container and around the portafilter, making sure that it is always at the right temperature to extract. This is important because even a few degrees can mean the difference between good and great espresso.
The Pump
The motorized pumps that are used in rotary espresso machine with frother (try Pageoftoday) machines provide the nine atmospheric bar pressure needed to extract espresso. This differs from manual piston machines that rely on a lever. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.
Pumps are generally less expensive and last longer than piston-driven machines. However, both kinds of machines may degrade because of frequent use and poor cleaning. Pumps are also more complicated mechanically, which can increase prices of even most basic models.
Some discount espresso machines machines use steam pressure instead of a pump to make espresso. The drawback of this is that the same boiler that produces steam also increases the temperature of the water until it reaches boiling and can result in over-extraction. Additionally these machines typically have to restore their pressure between cups, which requires time and energy.
Many espresso machines use a rotary or vibration pump. A vibration model makes use of the vibrating disk to create pressure, while a rotary model pushes hot water through the ground at a high speed. Both types of machines can make excellent espresso, however rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is the one that heats the water to the perfect temperature for extraction. The steam that is produced gets to the portafilter which contains the small espresso machine coffee grounds. It is then pumped into the cup. During this process the steam generates enough pressure to push the grounds of the coffee through. This results in a layer of crema that is then poured over. 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 the temperature of the brew. There are a variety of ways to control the amount of brew, as well as the size of cup that can be produced by the machine.
The first espresso machines were steam-type. They had a single boiler to make both brew and steam, however, the pressure they could produce was very low - just two bars of atmospheric pressure maximum. This led to the coffee machines espresso tasting burnt and bitter. This is the reason Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most common espresso maker is a semi-automatic machine with an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic machine, you must grind the beans and tamp them by hand. The pump is able to regulate the flow of water and pressure. This is a great compromise between human control and mechanized reliability.
The Filter
Espresso machines typically have a filter that separates the grounds of the coffee from hot water. The filter is also a vital component of the machine's temperature control, as it prevents overheating.
It also enhances flavor, as it can allow for a longer bloom phase. This helps the beans let their nuances out and provides an opportunity for better extraction.
It is important to remember that even the finest filter could result in a poor cup of coffee. The quality of the beans and the extraction process remain crucial.
This is where the magic happens, it's the thing that makes espresso taste great. The grouphead, often referred to as the brewhead, is where the portafilter (the thing you put the coffee ground into) sits when you're making espresso.
Steam-driven espresso machines use hot water that is heated in an airtight container to produce steam. The steam then pushes hot water through grounds of coffee under high pressure. These machines are less expensive and easier to maintain than pumps-driven models. They are however limited in their ability for creating the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent times, espresso machines powered by a compressed air compressor have become increasingly popular. They use an air-compressor to push hot water across the ground and are much more mobile than electric steam-driven espresso machines.