How Does Machine Espresso Work?

The machine espresso makes use of precision pressure, and filter technology that is awe-inspiring to make the coffee and espresso maker you love. What exactly is it?

cafe espresso machine is created by forcing hot water under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However the pressure is the main difference.

The Head of the Group

As the name suggests the group head is the place you place your portafilter when brewing espresso. It disperses the water into the portafilter, and regulates the pressure during the extraction. There are several different types of group heads each with its unique advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion capabilities, and still others are designed to control the lever. Some include a combination such as the E61. This is a favorite among baristas because it offers multiple advantages in one package.

As you can see in the image above, the group head is equipped with several notches. It is possible to place your portafilter in these notches and then twist the head to lock it. There is also a gasket of rubber that resides inside the notches, which helps create an airtight seal when you insert your portafilter into the machine. The notches allow for an exact placement of the portafilter. This is crucial for an accurate extraction.

The group head is not just able to allow you to insert your portafilter easily, but it also maintains a constant temperature. It does this by circulating hot water through the brew basket, and around the portafilter, making sure that it's always at the correct temperature for extraction. This is vital, because just a few degrees could make the difference between a good and excellent espresso maker.

The Pump

Contrary to manual piston machines which rely on a lever to pressurize water, the rotary espresso machines use motorized pumps to deliver the nine atmospheric bars of pressure necessary for espresso extraction. This pressure is generated by pumping water through a heat exchanger and then through the ground coffee.

Pumps are generally less expensive and last for longer than piston-driven machines. However, both types of machines can degrade because of frequent use and insufficient cleaning. They also create mechanical complexity, which can result in an expensive price for even the most basic models.

Certain espresso machines utilize steam pressure instead of a pump to make best cheap espresso machine. The disadvantage of this is that the same boiler that produces steam also raises the temperature of water to the point of boiling which can cause excessive extraction. These machines also have to continuously rebuild their pressure between cups. This takes energy and time.

Many espresso machines utilize either a rotary or vibration pump, with a vibrating model using a vibrating disc to create pressure and the rotary model pushing hot water through the grounds under high speed. Both machines can produce excellent espresso but rotary machines are more quiet, durable and less likely to break down.

The Boiler

The boiler heats the water to a temperature that is ideal to extract. The resulting steam reaches the portafilter that contains the ground espresso and gets funnelled down into the cup. During this process the steam creates enough pressure to push the grounds of coffee through. This results in a layer crema on top. This is one of the hallmarks of a good espresso.

There are three distinct types of espresso machines espresso, each having distinct pumps and the temperature of the brew. There are many ways to control the brew and the size of the cup that can be made by the machine.

The first home espresso machine machines were steam-type. They used a single boiler to make both steam and brew, however the pressure they were able to create was minimal - two bars of atmospheric pressure, at most. The coffee tasted bitter and burned. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most popular espresso machine is a semiautomatic with an electric pump. When people think of espresso machines, they picture these machines. If you have a semi-automatic machine you have to grind the beans and tamp them yourself but the pump controls the flow of water and pressure. This is a great compromise between the human touch and the mechanised quality.

The Filter

Espresso machines usually use a filter that separates the grounds of the coffee from the hot water. The filter is also an important component of the temperature control system, as it prevents the machine from overheating.

It also aids in flavor as a filter lets you enjoy a longer bloom phase. This allows the beans to let their nuances out, and allows for a better extraction.

However, it is important to keep in mind that even a top filter could result in a bad cup of coffee, since the quality of the beans and extraction is still essential.

This is where the magic happens. It's what makes espresso taste great. The grouphead (also known as the brewhead) is where you place the portafilter, the device that you put the coffee grounds into, while making espresso.

In the steam-driven espresso machine hot water is heated in an airtight tank to create steam, which is then pushed through the grounds at high pressure. These types of machines are usually less expensive and easier to maintain than pump-driven models. They are however limited in their ability to create the ideal conditions for brewing as 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 use an air compressor to force hot water through the grounds and are significantly more portable than electric steam-driven machines.