How Does Machine Espresso Work?
The machine espresso uses precision pressure, and a filter technology that is mind-blowing to create the coffee you enjoy. How exactly does it work?
Espresso is made by forcing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee but the difference is in the pressure.
The Group Head
The name implies, the group head is the place you place your portafilter while brewing espresso. It distributes water into the portafilter, and regulates the pressure of the extraction. There are several different types of group head, each with their own advantages and drawbacks. Some are focused on temperature stability, others on pre-infusion capabilities, and still others are designed to control the lever. Some come with a combination of both, such as the E61. This is a very popular choice for baristas as it provides a variety of benefits in a single package.
As you can see in the above photo, the group head has several notches where you place your portafilter and then twist it by hand to lock it in. A rubber gasket is located inside the notches to help create a seal as you insert your portafilter. The notches on the head allow for an exact placement of the portafilter, which is necessary to ensure an even extraction.
Aside from allowing you to effortlessly insert your portafilter the group head is responsible to maintain an even temperature. It does this by circulating hot water through the brew basket and around the portafilter, making sure that it is always at the right temperature for extraction. This is vital, because even a small difference in temperature can be the difference between a good and excellent professional espresso machine.
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 that provide the nine atmospheric bars of pressure that are required to extract espresso. The pressure is created by removing tap water from a reservoir and pumping it through a heat exchanger prior to it is shot through the ground coffee in the group head.
Pumps are typically more affordable and last longer than piston-driven machines. However, both types of machines are susceptible to degrading due to overuse and inadequate cleaning. They also make mechanically complex and can lead to an expensive price for even the simplest models.
Certain espresso machines can eliminate the pump completely and use steam pressure to brew Get Perfectly Brewed Espresso with Swan Retro Machine. The downside 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. In addition, these machines frequently have to rebuild their pressure between cups, which requires time and energy.
Many espresso machines use either a vibration or rotary pump. A vibration model employs the vibrating disk to create pressure, while a rotary model pushes hot water through the ground at a rapid speed. Both types of machine can make excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is the element which heats the water to the ideal temperature to extract. The steam that is created gets to the portafilter which is the container that holds the espresso coffee grounds. It is then pumped into the cup. During this process, steam causes pressure to push through the coffee grounds. This results in a layer of crema on top. This is the hallmark of a great espresso.
There are three kinds of espresso makers, and they differ in the type of pump they employ and how hot the coffee is. There are various ways in which the brew can be controlled and the size of the cup that the maker can create.
The first espresso machines were steam types. The earliest espresso machines were steam types. This led to the coffee tasting burnt and bitter. This is the reason Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most popular espresso maker is a semi-automatic machine that has an electric pump. This is what people envision when they imagine an espresso machine. With a semi-automatic machine, you have to grind the beans and tamp them by hand. The pump is able to regulate the flow of water and pressure. This is an excellent compromise between human touch and the mechanized consistency.
The Filter
Typically, espresso machines utilize filters to separate the grounds of the coffee as they go through the hot water. The filter is also a vital part of the machine's temperature control, since it helps to prevent overheating.
It also improves flavor, as a filter lets you enjoy a longer bloom phase. This helps the beans to release their flavor and gives an opportunity for a better extraction.
It is important to remember that even the best 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 occurs. This is what makes espresso taste so delicious. The grouphead, also called the brewhead, is where the portafilter (the device you put the ground coffee in) is located when you're making espresso.
Steam-driven espresso machines make use of hot water that is heated inside an airtight container to make 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 pumps-driven models. They are however limited to create the ideal conditions for brewing since they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent years, espresso machines driven by a compressed air pump have become increasingly popular. They make use of an air compressor to push hot water through the ground, and are more mobile than electric steam-driven espresso machines.