How Does Machine Espresso Work?
Machine espresso utilizes precise pressure and mind-blowing filter technology to make the perfect cup of coffee. What exactly is it that makes it work?
Espresso is produced by pushing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee but the 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 the water into the portafilter, and controlling the pressure of the extraction. There are several different types of group head each with its particular advantages and drawbacks. Some are designed for temperature stability while others are specifically designed 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, which is to be the most popular among baristas for its ability to provide multiple benefits in one package.
As you can see in the above image The group head features several notches where you put your portafilter, then twist it by hand to secure it. There is also a rubber gasket that resides inside the notches and helps create an airtight seal when you insert your portafilter into the machine. The notches allow for precise placement of your portafilter. This is essential for a consistent extraction.
Aside from allowing you to easily place your portafilter in, the group head is responsible for maintaining a consistent temperature. This is done by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is always at the right level for extraction. This is vital, because even a few degrees can mean the difference between good and great espresso.
The Pump
The motorized pumps used in espresso machines that rotate provide the nine atmospheric bar pressure needed to extract espresso. This is different from manual piston machines that rely on levers. This pressure is generated by pumping water through a heat exchanger and then through the ground coffee.
Pumps tend to be cheaper and last longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of frequent use and inadequate cleaning. Pumps are also more complex mechanically, which can raise the price of even the simple models.
Some espresso machines do away with the pump entirely and make use of steam pressure to make best espresso machine. The downside is that the same boiler that produces steam also increases the temperature of water to the point of boiling which could lead to excessive extraction. The machines must also continually rebuild their pressure between cups. This takes energy and time.
Many espresso machines use either a vibration or rotary pump. A vibration model makes use of the vibrating disk to create pressure, whereas a Rotary model pushes hot coffee through the ground at a fast speed. Both machines espresso machines can make excellent espresso, but rotary machines are more quiet, durable and less likely to break.
The Boiler
The boiler is the element that heats the water to the optimal temperature to extract. The steam that is produced reaches the portafilter, which contains the ground best espresso machine coffee, and is then pumped into the cup. The steam is able to create enough pressure to push the coffee grounds through. This results in a whipped-up the top of the espresso. This is one of the main characteristics of a good espresso.
There are three types of espresso makers, and they differ in the type of pump they employ and how hot the espresso is. There are various ways in which the brew can be controlled as well as the size of the cup the machine is capable of making.
The first espresso and filter coffee machine machines were steam-based. The earliest espresso machines were steam types. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was designed by the Milanese producers 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 imagine an espresso machine. With a semi-automatic espresso machine, you need to grind the beans and tamp them by hand, but the pump controls the flow of water and pressure. This is a fantastic solution that combines human control with mechanized reliability.
The Filter
Typically, espresso machines have a filter to separate out the grounds of coffee as they move through the hot water. The filter is also a vital component of the temperature control system, since it helps prevent the machine from overheating.
It also aids in flavor, as it can allow for a longer bloom phase. This allows the beans to release their flavors and provides an opportunity for better extraction.
However, it is important to remember that even a top filter can make a terrible cup of coffee, as the quality of the beans and extraction are vital.
It's here that the magic happens. This is the reason why espresso tastes so good. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy that you put the grounds of your coffee into when making espresso.
In the steam-driven espresso machine coffee machine hot water is heated in an airtight container to create steam. This is then pushed through the grounds at a high pressure. These kinds of machines are generally less expensive and simpler to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the ideal conditions for brewing as they only operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.
In recent years, compressed air-driven espresso machines have become more popular. They utilize an air compressor to force hot water through the ground, and are more mobile than steam-driven electric espresso machines.