How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the perfect cup of coffee. How exactly does it work?
Espresso is made by pushing hot water at high pressure through finely-ground
coffee for espresso machine. The process is similar to that of making drip coffee. However the pressure is the primary difference.
The Group Head
The name implies, the group head is the place you place your portafilter when brewing espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the resulting extraction. There are various kinds of group heads each with its distinct advantages and disadvantages. Some are designed for the stability of temperature while some are built to handle pre-infusion. Some are designed to control the lever. There are even some that include a mix of features, such as the E61 one, which is the classic choice among many baristas for its ability to offer multiple benefits in one package.
As you can see in the image above The group head features several notches to place your portafilter before twisting it manually to secure it. There is also a gasket of rubber in the notches and helps create the seal when you insert your portafilter into the machine. The notches permit precise placement of the portafilter. This is crucial for an accurate extraction.
Aside from allowing you to effortlessly insert your portafilter the group head is also responsible for maintaining a consistent temperature. It does this by cycling hot water through the brew basket, and around the portafilter to ensure that it's always at the correct temperature to extract. It is crucial to keep in mind that even a slight differences can make the distinction between a decent and a great espresso.
The Pump
In contrast to piston machines that are manually operated, that use a lever to pressurize water, rotating espresso machines rely upon motorized pumps that provide the nine atmospheric bars of pressure required to extract espresso. The pressure is created by pumping water through a heat exchanger and then through the ground coffee.
Pumps tend to be cheaper than piston-driven models, and they tend to last longer, however both types of machines may get damaged through overuse and lack of cleaning. Pumps are also more complex mechanically, which can raise the cost of even the simple models.
Some espresso machines do away with the pump completely and instead use steam pressure to brew espresso. This can cause over-extraction because the boiler that makes steam also heats the water to boil. These machines also have to constantly rebuild their pressure between cups. This takes energy and time.
A majority of espresso machines utilize a rotary or vibration pump. A vibration model makes use of the vibrating disk to create pressure, while a circular model pushes hot liquid through the ground at a high speed. Both types of machine can make a great espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is what makes the water warm to the ideal temperature for extraction. The steam produced will eventually reach the portafilter, which contains the espresso
coffee and espresso maker grounds. It is then poured into the cup. The steam creates pressure to push through the grounds of the coffee. This creates a crema on top of the espresso. This is a sign of a good espresso.
There are three kinds of espresso machines, each with distinct pumps and the temperature of the brew. There are many ways to control the strength of the brew and the size of cup that can be produced by the machine.
The first
buy espresso machines machines were steam-type. They utilized a single boiler to make both steam and brew, but the pressure they could produce was very low - just two bars of atmospheric pressure at the most. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso machine is a semiautomatic model with an electric pump. These are what people imagine when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans yourself however the pump controls the flow of water and pressure. This is an excellent compromise between human touch and the mechanized consistency.
The Filter
Typically, espresso machines use a filter to separate out the grounds of coffee as they move through the hot water. The filter is also an essential component of the machine's temp control, as it prevents overheating.
A filter also improves flavor because it allows for an extended flowering time. This lets the beans release their flavor and allows for better extraction.
It is important to keep in mind that even the finest filter can make a bad cup of coffee. The quality of the beans and the extraction process are still very important.
It's in this area that the magic takes place. This is what makes espresso taste so good. The grouphead (also known as the brewhead) is where you place the portafilter, the device which you put the grounds of coffee into when making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight tank
best bean to cup espresso machine create steam, which is then pushed through the grounds under
high End espresso machine pressure. These types of machines are usually cheaper and easier to maintain than pumps-driven models. However, they are limited in their ability to provide the ideal conditions for brewing since they are only operating at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.
In recent years, compressed air pump-driven espresso machines have become more popular. They make use of an air compressor to push hot water across the ground. They are also more mobile than steam-driven electric espresso machines.