The 9 Things Your Parents Teach You About Machine Espresso

How Does Machine Espresso Work?

Machine espresso employs precise pressure and mind-blowing filter technology to create the coffee we love. What exactly does it work?

Espresso is made by pushing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee. However the pressure is the major difference.

The Head of the Group

As the name suggests the group head is where you place your portafilter when making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the extraction. There are various kinds of group head, each with their particular advantages and disadvantages. Some are designed to provide stability in temperature, while others are built to handle pre-infusion. Others are built to control the lever. There are even some that include a mix of features, like the E61, which is the standard choice for many baristas for its ability to offer multiple benefits in a single package.

As you can see in the above image the group head comes with several notches where you put your portafilter, then twist it manually to secure it. A rubber gasket is located in the notches to create a seal as you insert your portafilter. The notches permit the precise placement of the portafilter. This is essential for an efficient extraction.

Aside from allowing you to easily place your portafilter in, the group head is responsible for maintaining an even temperature. It does this by circulating hot water through the brew basket and around the portafilter to ensure that it's always at the correct temperature to extract. It is important to note that even a few degree deviation can make the difference between a decent and a great espresso.

The Pump

Motorized pumps in rotary espresso machines provide the nine atmospheric bar pressure that is required for espresso machine with grinder extraction. This differs from manual piston machines which use a lever. This pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger prior being pushed through the ground coffee inside the group head.

Pumps are generally cheaper and last longer than piston-driven machines. However, both types of machines can degrade due to overuse and poor cleaning. Pumps are also more complex mechanically, which could increase prices of even most basic models.

Certain espresso machines do away with the pump completely and instead utilize steam pressure to make espresso. This could lead to over-extraction since the boiler that makes steam also heats the water until it comes to a boil. The machines espresso must also continually rebuild their pressure between cups. This requires energy and time.

A large majority of espresso machines employ an rotary or a vibration pump. A vibration model uses an oscillating disk to create pressure, while a rotating model pushes hot water through the ground at a high speed. Both machines can make great espresso, however rotary machines are more stable, quieter and less likely to fail.

The Boiler

The boiler is the component which heats the water to the ideal temperature for extraction. The resulting steam reaches the portafilter, which contains ground espresso beans and is then pumped down into the cup. During this process the steam generates enough pressure to push the grounds of coffee through. This produces a layer of crema on top. This is the hallmark of a good espresso.

There are three kinds of espresso makers, and they differ in the kind of pump they use and how hot the brew is. There are also different ways in which the brew could be controlled, as well as the size of the cup that the machine can produce.

The first espresso machines were steam types. The first best espresso machine under 200 machines were steam types. The coffee tasted bitter and burned. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most popular espresso maker is a semi-automatic machine that has an electric pump. These are the things people think of when they think of an espresso machine. Semi-automatic machines require you to grind and tamp your beans yourself however the pump controls the water flow and pressure. This is a great combination of human control and mechanised consistency.

The Filter

Typically, espresso machines utilize filters to separate 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, since it stops overheating.

It also enhances flavor as a filter allows for a longer bloom time. This allows the beans to let their nuances out, and also allows for 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 is still essential.

It's in this area that the magic takes place. This is what makes espresso taste so good. The grouphead, often called the brewhead, is where the portafilter (the container you place the coffee ground into) sits when you're making espresso.

Steam-driven espresso machines use hot water that is heated in an airtight vessel to create steam. The steam then pushes hot water through coffee grounds under high pressure. These machines are less expensive and are easier for the user to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the perfect brewing conditions since they are only operating at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.

In recent years, compressed air-pump-driven espresso machines have been gaining popularity. They use an air compressor to push hot water through the ground. They are also more mobile than electric steam-driven espresso machines.