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 that makes it work?

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

The Group Head

As the name implies the group head is where you place your portafilter while brewing espresso. It distributes water into the portafilter, and then regulates the pressure during the extraction. There are many different types of group heads each with their own advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion capabilities, and Machine Espresso still others are designed to control the lever. There are some that include a mix of features, like the E61 that is the most popular choice among baristas due to its capacity to offer multiple benefits in a single package.

As you can see from the image above, the group head is fitted with several notches. It is possible to place your portafilter in these notches, then twist the head to lock it. There is also a gasket of rubber in the notches and helps create the seal when you insert your portafilter into the machine. The notches on the head allow for a precise location of the portafilter which is essential to ensure an even extraction.

The group head does not just allow you to place your portafilter easily however it also keeps 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 at the right level for extraction. This is important because just a few degrees could make the difference between excellent and great espresso.

The Pump

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

Pumps tend to be less expensive than piston-driven machines, and they tend to last longer, although both types of machines could degrade with overuse and insufficient cleaning. Pumps are also more complex mechanically, which can raise the price of even the simplest models.

Certain espresso machines utilize steam pressure instead of a pump in order to brew espresso. This can result in over-extraction because the boiler that produces steam also warms the water to boil. Additionally the machines often have to rebuild their pressure between cups, which requires time and energy.

Many espresso machines make use of an rotary or Machine Espresso a vibration pump. A vibration model utilizes an oscillating disk to create pressure, while the rotating model pushes hot water through the ground at a fast speed. Both machines can make great espresso but rotary machines are quieter, more durable and less likely to break.

The Boiler

The boiler is what heats the water to the right temperature to extract. The steam produced is then directed to the portafilter, which is the container that holds the espresso coffee grounds. The steam is then channeled into the cup. The steam causes enough pressure to push the grounds of the coffee through. This creates a crema on top of the espresso. This is the hallmark of a great espresso.

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

The first espresso machines were steam-type. They used a single boiler to make both steam and brew however, the pressure they could generate was low - only two bars of atmospheric pressure at most. The coffee tasted bitter and burnt. This is the reason why Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most commonly used espresso machine is a semiautomatic with an electric pump. When people think of espresso coffee maker machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans on your own, but the pump regulates the water flow and pressure. This is a great compromise between the human touch and the mechanised consistency.

The Filter

Typically, espresso machines use filters that separate the grounds of coffee as they move through the hot water. The filter is also a vital component of the temperature control system, as it prevents the machine from overheating.

It also enhances flavor, since a filter lets you enjoy a longer bloom phase. This lets the beans release their flavor and improves extraction.

It is important to keep in mind that even the best filter can result in a bad cup of coffee. The quality of the beans, as well as the extraction, are still very important.

It's here that the magic happens. This is what makes espresso taste so delicious. The grouphead (also called the brewhead) is where you put the portafilter, the device that you put the coffee grounds into, when making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to create steam. The steam then moves hot water through the coffee grounds under high pressure. These types of machines are typically less expensive and easier to maintain than pumps-driven models. They are however limited in their ability to create the perfect brewing conditions as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They utilize an air compressor to force hot water through the grounds and are significantly more portable than electric steam-driven machines.