How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and amazing filter technology to make the coffee we love. How exactly does it work?

professional espresso machine is created by forcing hot water 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 group head is the portafilter that you insert when brewing espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure that results from the extraction. There are a variety of types of group head each with its unique advantages and disadvantages. Some are specifically designed for the stability of temperature while some are specifically designed to handle pre-infusion. Some are designed to control the lever. There are some that include a mix of features, like the E61, which is considered the classic choice among many baristas due to its ability to provide multiple benefits in one package.

As you can see in the image above The group head features many notches in which you can place your portafilter before twisting it by hand to lock it in. A gasket made of rubber is positioned inside the notches, which helps create a seal while you insert your portafilter. The notches on the head permit an exact placement of the portafilter, which is necessary to ensure an efficient extraction.

The group head is not just able to allow you to put in your portafilter easily however it also keeps the same temperature. It does this by circulating hot water through the brew container and around the portafilter, ensuring that it's always at the correct temperature to extract. This is vital, because even a small difference in temperature can make the difference between good and great espresso.

The Pump

In contrast to manual piston machines that use a lever to pressurize water, rotating espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure necessary to extract espresso. The pressure is created by pumping water through a heat exchanger and then through the ground coffee.

Pumps are generally less expensive than piston-driven machines, and they tend to last longer. However, both types of machines could be damaged by excessive use and inadequate cleaning. They also create mechanical complexity, which can result in the cost of even the simplest models.

Certain espresso machines can eliminate the pump completely and use steam pressure to brew espresso. The disadvantage of this is that the boiler that produces steam also increases the temperature of the water until it reaches boiling and can result in excessive extraction. They also have to constantly rebuild their pressure in between cups. This requires energy and time.

A large majority of espresso machines employ an rotary or a vibration pump. A vibration model makes use of an oscillating disk to create pressure, whereas a circular model pushes hot liquid through the ground at high speed. Both machines can make great espresso, but rotary machines are quieter, more durable and less likely to break down.

The Boiler

The boiler is the one that is used to heat the water to the perfect temperature to extract. The resulting steam is then transferred to the portafilter that contains the ground home espresso machine coffee, and is then pumped down into the cup. During this process the steam is able to create enough pressure to push the grounds of the coffee through. This creates a layer 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 having distinct pumps and brew temperature. There are a variety of ways in which the brew can be controlled and the dimensions of the cup the machine is capable of making.

The first espresso machines were steam-based. They had one boiler to make both steam and brew but the pressure they could produce was very low - just two bars of atmospheric pressure maximum. The coffee tasted bitter and burned. This is why Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most popular espresso machine is a semiautomatic one with an electric pump. When people think of espresso machines, they think of these machines. With a semi-automatic machine you grind the beans and tamp them by hand. However, the pump controls the flow of water and pressure. This is a great compromise between the human touch and mechanized consistency.

The Filter

Typically, espresso machines utilize a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also a vital part of the temperature control system, as it prevents the machine from overheating.

It also aids in flavor, as it lets you enjoy a longer bloom phase. This helps the beans to release their flavor and gives an opportunity to improve extraction.

However it is crucial to remember that even a good filter can make a terrible cup of coffee, as the quality of the beans and extraction are vital.

This is where the magic happens. It's what makes an espresso really taste good. The grouphead, also called the brew head, Machine Espresso is the place where the portafilter (the device you put the coffee ground into) sits when you're making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to produce steam, which then pushes the hot water through the grounds at high pressure. These kinds of machines are generally less expensive and simpler to maintain than pump-driven models. However, they are not as efficient in their ability to create the ideal conditions for brewing because they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

In recent years, espresso machines driven by a compressed air compressor have become increasingly popular. They use an air compressor to force hot water into the grounds and are more portable than electric steam-driven machines.