How Does Machine Espresso Work?

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

To make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee, but the key difference is in the pressure.

The Group Head

The name implies, the group head is where you put your portafilter in when brewing espresso and filter coffee machine. It distributes water into the portafilter, and regulates the pressure of the extraction. There are various kinds of group head each with its unique advantages and disadvantages. Some focus on temperature stability, while others on pre-infusion features, and others are designed to control the lever. Some are a combination, such as the E61. This is a popular choice among baristas as it provides a variety of benefits in a single package.

As you can see from the photo above the group head has a number of notches. The portafilter is placed in these notches and then twist the head to secure it. A gasket of rubber is situated inside the notches, which helps make a seal when you insert your portafilter. The notches permit precise placement of the portafilter. This is crucial to ensure an accurate extraction.

The group head not only lets you to put in your portafilter easily, but it also maintains the temperature at a constant level. It does this by cycling hot water through the brew pan and around the portafilter, ensuring that it is always at the correct temperature for extraction. It is important to remember that even a small difference can make the difference between a good and excellent espresso.

The Pump

In contrast to manual piston machines which rely on a lever to pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure needed to extract espresso. The pressure is built by pumping water through a heat exchanger and then through the ground coffee.

Pumps tend to be cheaper than piston-driven machines, and tend to last longer, however both types of machine can become damaged due to excessive use and poor cleaning. They also add mechanical complexity that can lead to an expensive price for even the simplest models.

Some espresso machines employ steam pressure instead of a pump for brewing espresso. This can result in over-extraction because the boiler that makes steam also causes the water to boil. These machines also have to constantly rebuild their pressure between cups. This takes energy and time.

Many espresso machines make use of an rotary or vibrating pump, which has a vibration model that uses a vibrating disc that generates the pressure and rotating models that push hot water through the grounds at high speed. Both machines produce great espresso however rotary machines tend to be more stable, quieter and less likely to fail.

The Boiler

The boiler makes the water warm to the right temperature to extract. The resulting steam reaches the portafilter that contains the ground espresso and is then pumped into the cup. The steam is able to create 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 main characteristics of a great espresso.

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

The earliest espresso machines were steam-based. The earliest espresso machines were steam-type machines. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was invented by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso machines home maker is a semi-automatic machine that has an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp the beans by yourself while the pump controls the flow of water and pressure. This is a great compromise between the human touch and mechanized accuracy.

The Filter

Espresso machines usually use a filter that separates the grounds of coffee from hot water. The filter is also an essential component of the machine's temperature control, since it helps to prevent overheating.

A filter also helps with flavor as it allows for a longer flowering phase. This lets the beans release their nuances, and improves extraction.

However, it is important to remember that even a great filter can result in a poor cup of coffee as the quality of the beans and extraction is still crucial.

It's here that the magic occurs. This is what makes espresso taste so good. The grouphead, often referred to as the brew head, is where the portafilter (the device you put the coffee grounds into) sits when you're making espresso.

Steam-driven espresso machines use hot water heated in an airtight vessel to create steam. The steam then pushes hot water through grounds of coffee under high pressure. These machines are less expensive and easier for the owner to maintain than pumps-driven models. However, they are limited in their capacity to create the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9 bar espresso machine-10 bar.

In recent times, Espresso home machine (Willysforsale.com) machines powered by compressed air-pump are becoming increasingly popular. They make use of an air compressor to push hot water across the ground and are much more mobile than steam-driven electric espresso machines.