How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. But how exactly does it work?
Espresso is produced by pushing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee, but the major difference is in the pressure.
The Group Head
The group head is the portafilter you put in when making espresso. It is responsible for dispersing water into the portafilter, and controlling the pressure of the extraction. There are a variety of types of group head each with its distinct advantages and drawbacks. Some focus on temperature stability, others on pre-infusion options, and others are designed to control the lever. Some are a combination, like the E61. This is a popular choice among baristas because it offers multiple advantages in a single package.
As you can see from the image above the head of the group has a number of notches. It is possible to place your portafilter in these notches, then twist the head to lock it. There is also a gasket made from rubber that is a part of the notches and helps to create the seal when you insert your portafilter into the machine. The notches allow for the precise placement of the portafilter. This is crucial to ensure an accurate extraction.
espresso machines uk does not just allow you to insert your portafilter easily however it also keeps the temperature at a constant level. It does this by circulating hot water through the brew pan and around the portafilter, ensuring that it's always at the correct temperature to extract. This is crucial, since just a few degrees could mean the difference between good and excellent espresso.
The Pump
In contrast to piston machines that are manually operated, that use a lever to pressurize water, the rotary espresso machines use motorized pumps to supply the nine atmospheric bars of pressure necessary to extract espresso. The pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pumped through the ground coffee in the group head.
Pumps tend to be less expensive and last longer than piston-driven machines. However, both kinds of machines can deteriorate because of excessive use and inadequate cleaning. Pumps are also more complex mechanically, which can raise prices of even simpler models.
Some espresso machines employ steam pressure instead of a pump to make espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of water until it reaches boiling, which can lead to excessive extraction. The machines also need to constantly rebuild their pressure between cups. This requires energy and time.
A majority of espresso machines use a vibration or rotary pump, with a vibrating model using a rotating disc to create pressure, and a rotary model pushing hot water through the grounds under high speed. Both models are capable of producing excellent espresso, but rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is the one that heats the water to a temperature that is ideal to extract. The resultant steam then reaches the portafilter containing ground espresso beans and is then pumped down into the cup. During this process, steam causes pressure to push through the coffee grounds. This creates a layer crema that is then poured over. This is one of the main characteristics of a good espresso.
There are three types of espresso makers, which differ in the type of pump they use and how hot the coffee is. There are different ways to control the brew as well as the size of the cup that can be produced by the machine.
The first espresso machines were steam-type. The first espresso machines were steam-type machines. This led to the coffee tasting bitter and burnt. The modern espresso machine was invented by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most common espresso machine is a semiautomatic that has an electric pump. These are the things people think of when they think of an espresso maker. If you have a semi-automatic machine you have to grind the beans and then tamp them by hand, but the pump controls the flow of water and pressure. This is a great compromise between the human touch and the mechanised consistency.
The Filter
Espresso machines typically use a filter that separates the coffee grounds from the hot water. The filter is also an essential component of the temperature control system, because it stops the machine from overheating.
Filters also aid in flavor, as it permits a longer flowering period. This lets the beans release their flavor and improves extraction.
However, it is important to remember that even a good filter could result in a bad cup of coffee, because the quality of the beans and extraction is still vital.
This is where the magic happens, it's what makes an espresso really taste good. The grouphead, also referred to as the brewhead, is where the portafilter (the container you place the coffee ground into) is placed when you're making espresso.
Steam-driven espresso machines make use of hot water that is heated inside an airtight container to create steam. The steam then moves hot water through the grounds of the coffee under pressure. These machines are less expensive and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect conditions for brewing, as they only operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.
In recent years, espresso machines driven by a compressed air pump have become increasingly popular. They use an air-compressor to push hot water through the ground, and are more mobile than electric steam-driven espresso machines.