How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the delicious coffee we enjoy. How exactly does it work?
In order to make espresso hot water is pushed 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 name implies the group head is where you place your portafilter when making espresso. It distributes water into the portafilter, and then regulates the pressure of the extraction. There are many different kinds of group heads each with its distinct advantages and drawbacks. Some are focused on temperature stability, whereas others on pre-infusion features, and others are designed to control the lever. Some have a combination, like the E61. This is a preferred choice for baristas since it provides multiple benefits in one package.
As you can see in the photo above the group head comes with several notches to put your portafilter, then twist it with your hands to secure it. A gasket made of rubber is positioned inside the notches to help make a seal when you insert your portafilter. The notches allow for precise placement of the portafilter. This is crucial for an even extraction.
The group head is not just able to allow you to put in your portafilter easily however it also keeps the temperature at a constant level. This is accomplished by cycling hot water around the portafilter and through the brew basin, ensuring the temperature is always right for extraction. This is crucial, since even a few degrees can make the difference between good and excellent espresso.
The Pump
Motorized pumps in espresso machines that rotate provide the nine atmospheric bar pressure required to extract espresso. This differs from manual piston machines which use a lever. The pressure is created by pumping water through a heat exchanger and then through the ground coffee.
Pumps are generally less expensive and last longer than piston-driven machines. However, both kinds of machines may degrade because of frequent use and insufficient cleaning. They also create mechanical complexity and can lead to an expensive price for even the simplest models.
Certain espresso machines eliminate the pump completely and instead utilize steam pressure to make espresso. The disadvantage of this is that the boiler that produces steam also increases the temperature of water until it reaches boiling and can result in over-extraction. These machines also have to constantly rebuild their pressure between cups. This takes energy and time.
A large majority of espresso machines employ either a vibration or rotary pump. A vibration model uses a vibrating disk to generate pressure, while a circular model pushes hot liquid through the ground at high speed. Both types of machine can make a great espresso, but the rotary models are quieter and more durable than vibration pumps.
The Boiler
The boiler is the one that is used to heat the water to the perfect temperature to extract. coffeee resulting steam is then transferred to the portafilter containing the ground espresso and is then pumped down into the cup. The steam generates enough pressure to push the grounds of the coffee through. This produces a layer of crema that is then poured over. This is one of the hallmarks of a good espresso.
There are three kinds of espresso makers, which differ in the type of pump they use and how hot the espresso is. There are different ways that the brew can be controlled as well as the size of the cup the machine is capable of making.
The earliest espresso machines were steam-based. The earliest espresso machines were steam types. The coffee tasted bitter and burned. The modern espresso machine was developed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic espresso machine, you must grind the beans and tamp them by hand. However, the pump regulates the flow of water and pressure. This is a fantastic compromise between human control and mechanised reliability.
The Filter
Typically, espresso machines utilize a filter to separate out the grounds of coffee as they move through the hot water. The filter is also an essential element of the temperature control system, since it helps prevent the machine from overheating.
A filter also improves flavor as it allows for an extended flowering time. This helps the beans release their flavor and gives an opportunity for a better extraction.
However, it is important to keep in mind that even a high-quality filter can make a terrible cup of coffee, since the quality of the beans and extraction are important.
It's here that the magic occurs. This is the reason why espresso tastes so good. The grouphead, often called the brew head, is the place where the portafilter (the container you place the coffee ground into) sits when you're making espresso.
In an espresso machine that is driven by steam, hot water is heated in an airtight tank to create steam. Steam is then pushed through the grounds at high pressure. These kinds of machines are typically cheaper and easier to maintain than pump-driven models. However, they are not as efficient in their capacity to create the ideal conditions for brewing since they are only operating at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.
In recent times, espresso machines powered by compressed air-pump are becoming increasingly popular. They use an air-compressor to force hot water into the ground and are more mobile than electric steam-driven espresso machines.