How Does Machine Espresso Work?

The machine espresso uses precision pressure, and filtering technology that is amazing to make the coffee you love. How exactly does it work?

To make an espresso hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the primary difference.

The Group Head

The name implies, the group head is where you place your portafilter when brewing best home espresso machine. It disperses the water into the portafilter, and regulates the pressure during the extraction. There are a variety of group heads each with distinct advantages and disadvantages. Some focus on temperature stability, some on pre-infusion options, and others are designed to control the lever. Some are a combination, like the E61. This is a favorite among baristas because it offers multiple advantages in one package.

As you can see in the above photo the group head comes with several notches where you put your portafilter, then twist it by hand to secure it. There is also a gasket of rubber which is located inside the notches, which helps create the seal when you insert your portafilter into the machine. The notches on the head permit a precise position of the portafilter which is necessary 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 cycling hot water through the brew basket, and around the portafilter, making sure that it is always at the correct temperature for extraction. This is important, as even a few degrees can mean the difference between excellent and great espresso.

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 deliver the nine atmospheric bars of pressure necessary to extract espresso. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger before being shot 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 deteriorate because of frequent use and inadequate cleaning. Pumps are also more complicated mechanically, and can add to the cost of even the most basic models.

Certain espresso machines utilize steam pressure instead of a pump for brewing espresso. The disadvantage 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 over-extraction. Additionally these machines typically have to rebuild their pressure between cups, which takes time and energy.

Many espresso machines use a rotary or vibration pump. A vibration model utilizes an oscillating disk to create pressure, whereas a rotary model pushes hot water through the ground at high speed. Both models can make a great espresso, but Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler heats the water to the ideal temperature to extract. The steam that is produced reaches the portafilter containing the ground espresso coffee and is then pumped into the cup. During this process the steam causes enough pressure to push the grounds of coffee through. This produces 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 machines, each with different types of pumps and brew temperature. There are a variety of ways in which the brew could be controlled, as well as the size of the cup that the machine is capable of making.

The first espresso machines were steam-based. The earliest espresso machines were steam types. 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 common espresso maker is a semi-automatic one that has an electric pump. This is what people envision when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans by yourself while the pump controls the water flow and pressure. This is an excellent compromise between human control and mechanised reliability.

The Filter

Typically, espresso machines employ filters to separate the grounds of coffee when they pass through the hot water. The filter is also an essential component of the temperature control system, as it keeps the machine from overheating.

It also improves flavor, as it can allow for a longer bloom time. This helps the beans release their nuances and gives an opportunity for a better extraction.

It is important to keep in mind that even the most efficient filter can make a bad cup of coffee. The quality of the beans and the extraction process remain crucial.

This is where the magic happens, and it's what makes espresso taste great. The grouphead, sometimes referred to as the brewhead, is where the portafilter (the thing you put the ground coffee into) is located when you're making espresso.

In the steam-driven espresso machine hot water is heated in an airtight tank to produce steam, which is then pushed through the grounds at high pressure. These machines are cheaper and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the ideal brewing conditions, brewing as they only operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.

In recent times, espresso machines powered by compressed air-pump are becoming increasingly popular. They use an air compressor to push hot water into the grounds and are more portable than steam-driven electric machines.