How Does Machine Espresso Work?

Machine espresso employs precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly is it?

Espresso is made by forcing hot water under high 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

The group head is the portafilter that is inserted when you are making espresso. It distributes water into the portafilter, and then controls the pressure of the extraction. There are many different kinds of group heads each with its unique advantages and drawbacks. Some are specifically designed for temperature stability while others are designed to handle pre-infusion. Some are designed to control the lever. There are also some that contain a variety of features, like the E61, which is the most popular choice 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 place your portafilter before twisting it manually to lock it in. There is also a gasket made of rubber that resides inside the notches and helps to create an airtight seal after inserting your portafilter into the machine. The notches allow for precise placement of your portafilter. This is crucial to ensure an accurate extraction.

The group head is not just able to allow you to place your portafilter easily, but it also maintains the temperature at a constant level. This is achieved by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is always at the right level for extraction. It is important to remember that even a slight variation can mean the difference between a decent and a great espresso.

The Pump

The motorized pumps used in espresso machines rotary provide nine atmospheric bar pressure needed to extract espresso. This is different from manual piston machines which use a lever. The pressure is created by removing tap water from a reservoir, and pumping it through a heat exchanger prior to being pushed through the ground coffee inside the group head.

Pumps are generally more affordable and last longer than piston-driven machines. However, both kinds of machines can deteriorate due to excessive use and insufficient cleaning. They also increase the complexity of mechanical systems and can lead to costly prices for Machine espresso even the most basic models.

Some espresso machines use steam pressure instead of a pump to brew espresso. The drawback of this is that the boiler that produces steam also increases the temperature of the water to the point of boiling, which can lead to excessive extraction. In addition these machines typically have to rebuild their pressure between cups, which takes time and energy.

A large majority of espresso machines employ either a vibration or rotary pump. A vibration model employs an oscillating disk to create pressure, whereas the rotating model pushes hot water through the ground at high speed. Both types of machine can make excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is what is used to heat the water to a temperature that is ideal to extract. The steam that is produced reaches the portafilter, which contains the ground espresso coffee and is then funneled down into the cup. During this process, the steam creates pressure and pushes through the coffee grounds. This creates a foam on the top of the espresso. This is a hallmark of a great home espresso machine.

There are three types of espresso machines, each with a different type of pump and brew temperature. There are many ways to control the strength of the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam-types. They utilized one boiler to create both brew and steam, however, the pressure they could produce was very low - just two bars of atmospheric pressure, at most. This led to the coffee tasting burnt and bitter. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp the beans yourself The pump, however, regulates the flow of water and pressure. This is a great combination of human control and mechanised reliability.

The Filter

Typically, espresso machines use a filter to separate out the grounds of the coffee as they go through the hot water. The filter is also a vital part of the machine's temperature control, as it prevents overheating.

It also enhances flavor, as a filter can allow for a longer bloom phase. This allows the beans to release their nuances, and also allows for better extraction.

However, it is important to keep in mind that even a great filter could result in a bad cup of coffee, as the quality of the beans and extraction is crucial.

It's in this area that the magic takes place. This is what makes espresso taste so good. The grouphead (also called the brewhead) is where you put the portafilter, which is the thingy that you use to put the coffee grounds in, when making espresso.

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

In recent years, compressed air-pump-driven espresso machines have become more popular. They use an air compressor to force hot water through the ground and are more mobile than electric steam-driven espresso home machine machines.