How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the delicious coffee we enjoy. But how exactly does it work?

Espresso is created by forcing hot water under pressure through finely ground coffee. The process is similar to that of making drip coffee. However it is the pressure that makes the main difference.

The Head of the Group

As the name implies the group head is where you place your portafilter when brewing espresso. It distributes water into the portafilter, and then controls the pressure of the extraction. There are a variety of types of group heads each with its particular 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. Some are a combination, like the E61. This is a popular choice among baristas as it provides a variety of advantages in one package.

As you can see in the image above, the group head has a number of notches. You can place your portafilter in these notches and then turn the head around to secure it. There is also a rubber gasket 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 for an accurate extraction.

Apart from allowing you easily insert your portafilter, the group head is also responsible for maintaining a consistent temperature. It does this by circulating hot water through the brew basket and around the portafilter, making sure that it is always at the correct temperature for extraction. It is important to note that even a slight variation can mean the difference between a great and a great espresso coffee machines.

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 that are required to extract espresso. 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 types of machines can deteriorate due to overuse and insufficient cleaning. They also add mechanical complexity which can result in costly prices for even the most basic models.

Some espresso machines use steam pressure instead of a pump to brew espresso. This could lead to over-extraction since the boiler that produces steam also heats the water until it comes to a boil. These machines espresso also have to continuously rebuild their pressure between cups. This requires energy and time.

Many espresso machines make use of the rotary or vibration pump, with a vibrating model that uses a vibrating disc to generate the pressure, and an rotary model that pushes hot water through the grounds under high speed. Both models are capable of producing excellent espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the element which heats the water to the ideal temperature to extract. The steam created reaches the portafilter, which contains the espresso coffee grounds. It is then funneled into the cup. The steam creates enough pressure to push the grounds of coffee through. This results in a whipped-up the top of the professional espresso machine for home. This is one of the hallmarks of a good espresso.

There are three distinct types of espresso machines, each having different pumps and the temperature of the brew. There are various 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-types. They had one boiler to create both steam and brew, however the pressure they were able to create was minimal - two bars of atmospheric pressure maximum. This resulted in the coffee tasting bitter and burnt. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most common espresso maker is a semi-automatic device with an electric pump. These are the images people have when they imagine an espresso machine. With a semi-automatic machine, you have to grind the beans and tamp them by hand. The pump provides regulated water flow and pressure. This is a great compromise between the human touch and the mechanized quality.

The Filter

Typically, espresso machines employ filters that separate the grounds of coffee as they move through the hot water. The filter is also an important part of the temperature control system, as it keeps the machine from overheating.

It also improves flavor, as it allows for a more prolonged bloom time. This allows the beans to let their nuances out, and also allows for better extraction.

It is important to keep in mind that even the best filter could result in a poor cup of coffee. The quality of the beans and the extraction, are still very important.

It's in this area that the magic occurs. This is the reason why espresso maker for home tastes so good. The grouphead, sometimes called the brew head, is the place where the portafilter (the container you place the ground coffee in) is placed when you're making espresso coffee machine home.

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

In recent years, compressed air-driven espresso machines have become more popular. They use an air compressor to push the hot water through the grounds and are more portable than steam-driven electric machines.