The Main Problem With Machine Espresso And How To Fix It
How Does Machine Espresso Work?
The machine espresso uses precision pressure, and a filter technology that is mind-blowing to create the coffee you love. How does coffee and espresso maker work exactly?
Espresso is made by pushing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.
The Group Head
The group head is the portafilter that you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter before controlling the pressure of the resulting extraction. There are numerous kinds of group heads each with its own advantages and drawbacks. Some are focused on temperature stability, while others on pre-infusion options, and others are designed to control the lever. There are even some that contain a variety of features, such as the E61, which is considered the most popular choice among baristas due to its capacity to provide multiple benefits in a single package.
As you can see in the image above, the group head has numerous notches that you can place your portafilter and twist it with your hands to secure it. A gasket made of rubber is placed inside the notches, which helps make a seal when you insert your portafilter. The notches on the head allow for a precise positioning of the portafilter which is vital for an efficient extraction.
The group head not only lets you to put in your portafilter easily, but it also maintains the temperature at a constant level. This is achieved by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is constant to extract the coffee. It is important to note that even a slight difference can make the difference between a good and a great espresso.
The Pump
In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotating espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure needed 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 they tend to last longer, however both types of machines can become damaged due to excessive use and poor cleaning. They also make mechanically complex, which can result in costly prices for even the most basic models.
Some espresso machines do away with the pump completely and make use of steam pressure to make espresso. The disadvantage of this is that the same boiler that produces steam also increases the temperature of the water to boiling, which can lead to over-extraction. The machines also need to continually rebuild their pressure between cups. This requires energy and time.
Many espresso machines utilize either a rotary or vibration pump, which is a vibration model using a vibrating disc to generate the pressure, and the rotary model pushing hot water through the grounds at 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 component that heats water to the ideal temperature to extract. The resultant steam then reaches the portafilter, which contains ground espresso beans and is then pumped into the cup. The steam causes enough pressure to push the grounds of the coffee through. This results in a layer crema on top. This is one of the hallmarks of a great espresso.
There are three distinct types of espresso machines, each with a different type of pump and brew temperature. There are a variety of ways to control the brew and the size of cup that can be made by the machine.
The first espresso machines were steam-types. The earliest espresso machines were steam-type machines. This resulted in the coffee tasting burnt and bitter. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most popular espresso machine is a semiautomatic that has an electric pump. These are the things people think of when they imagine an espresso machine. With a semi-automatic machine you must grind the beans and then tamp them yourself but the pump provides regulated water flow and pressure. This is an excellent compromise between human touch and the mechanized consistency.
The Filter
Typically, espresso machines use filters to separate the grounds of coffee as they move through the hot water. The filter is also a crucial part of the temperature control system, since it helps prevent the machine from overheating.
It also helps with flavor, as a filter lets you enjoy a longer bloom time. This lets the beans let their nuances out, and allows for better extraction.
It is important to remember that even the most efficient filter could result in a poor cup of coffee. The quality of the beans, as well as the extraction, remain vital.
It's here that the magic takes place. This is the reason why espresso tastes so good. The grouphead, often referred to as the brewhead, is where the portafilter (the thingy you put the coffee ground into) is placed when making espresso.
Steam-driven espresso machines use hot water heated in an airtight container to create steam. The steam then pushes hot water through grounds of the coffee under pressure. These kinds of machines are typically cheaper and easier to maintain than pump-driven models. They are however limited in their ability to create the perfect conditions for brewing since they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent years, compressed-air-pump-driven espresso machines have been gaining popularity. They use an air-compressor to force hot water into the ground and are more mobile than electric steam-driven espresso machines.