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How Does Machine Espresso Work?

Machine espresso employs precise pressure and incredible filter technology to produce the delicious coffee we enjoy. How exactly does it work?

To make espresso hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However, it is the pressure that makes the main difference.

The Head of the Group

The group head is the portafilter you place in the espresso maker when making it. It distributes water into the portafilter and regulates the pressure of the extraction. There are a variety of group heads, each with its own advantages and drawbacks. Some are focused on temperature stability, some on pre-infusion capabilities, while others are designed to control the lever. There are even some that contain a variety of features, such as the E61 one, which is the classic choice among many baristas due to its ability to offer multiple perks in a single package.

As you can see in the image above the group head comes with several notches to place your portafilter before twisting it with your hands to lock it in. There is also a gasket made of rubber which is located inside the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches allow for precise placement of your portafilter. This is crucial for a consistent extraction.

The group head not only allows you to place your portafilter easily however it also keeps an even temperature. This is done by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is at the right level to extract the coffee. This is vital, because just a few degrees could mean the difference between good and excellent espresso.

The Pump

The motorized pumps used in rotary espresso machines supply the nine atmospheric bar pressure that is required for espresso extraction. This differs from manual piston machines that rely on levers. The pressure is built by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be less expensive than piston-driven machines and tend to last longer, although both types of machine can be damaged by excessive use and inadequate cleaning. Pumps are also more complex mechanically, which could increase the cost of even the simplest models.

Some espresso machines use steam pressure instead of a pump to make espresso. This can cause over-extraction because the boiler that produces steam also heats the water until it comes to a boil. Additionally these machines typically have to restore their pressure between cups, which requires time and energy.

Many espresso maker for home machines make use of the rotary or vibration pump. A vibration model uses a rotating disk to generate pressure, while a rotating model pushes hot water through the ground at high speed. Both types of machine can produce an excellent espresso, however Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the element which heats the water to the optimal temperature for extraction. The resultant steam then reaches the portafilter containing ground espresso beans and gets funnelled down into the cup. During this process the steam generates enough pressure to push the coffee grounds through. This results in a layer of crema that is then poured over. This is one of the hallmarks of a great espresso.

There are three types of espresso makers. They differ in the kind of pump they use and how hot the brew is. There are different ways in which the brew can be controlled as well as the dimensions of the cup the maker can create.

The first espresso machines were steam types. The first espresso machines were steam-type machines. The coffee tasted bitter and burnt. This is the reason why Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most common espresso machine is a semiautomatic one with an electric pump. These are the things people think of when they think of an espresso maker. With a semi-automatic machine you have to grind the beans and then tamp them by hand. However, the pump provides regulated water flow and pressure. This is a great compromise between the human touch and the mechanised quality.

The Filter

Typically, espresso machines employ a filter to separate out the grounds of coffee machines espresso as they move through the hot water. The filter is also an essential element of the temperature control system, as it prevents the machine from overheating.

It also enhances flavor, as it can allow for a longer bloom phase. This lets the beans release their flavors, and also allows for better extraction.

It is important to remember that even the best filter could result in a poor cup of coffee espresso machines. The quality of the beans as well as the extraction, are still crucial.

This is where the magic happens, and it's what makes an espresso really taste good. The grouphead (also called the brewhead) is where you put the portafilter, the thingy that you put the coffee grounds into, while making espresso.

In the steam-driven espresso machine hot water is heated in an airtight container to create steam. Steam is then pushed through the grounds under high pressure. These types of machines tend to be less expensive and easier to maintain than pump-driven models. They are however limited to create the perfect conditions for brewing since they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

In recent years, compressed-air-pump-driven espresso machines have been gaining popularity. They utilize an air compressor to push the hot water through the grounds and are more portable than steam-driven electric machines.