How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to make the perfect cup of coffee. But how exactly does it work?

In order to make espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, but the major difference is in the pressure.

The Group Head

The name implies, the group head is the place you place your portafilter when making espresso. It disperses water in the portafilter and regulates the pressure of extraction. There are many different types of group heads, each with its own advantages and drawbacks. Some are designed for temperature stability while others are designed to handle pre-infusion. Others are built to control the lever. Some have a combination, such as the E61. This is a favorite among baristas due to the fact that it has multiple benefits in one package.

As you can see from the picture above, the group head is equipped with several notches. The portafilter is placed into these notches and turn the head around to secure it. A gasket of rubber is situated within the notches to create a seal as you insert your portafilter. The notches on the head allow for an exact placement of the portafilter, which is necessary for a consistent extraction.

The group head not only lets you to put in your portafilter easily however, it also keeps an even temperature. It does this by cycling hot water through the brew container and around the portafilter, ensuring that it is always at the right temperature to extract. It is important to remember that even a few degree deviation can make the difference between a decent and a great espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure required for espresso extraction. This pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger before being pumped through the ground coffee inside the group head.

Pumps are generally cheaper and last longer than piston-driven machines. However, both types of machines may degrade because of frequent use and poor cleaning. Pumps are also more complex mechanically, which can increase prices of even most basic models.

Some espresso machines make use of steam pressure instead of a pump to brew espresso. This can lead to over-extraction as the boiler that produces steam also heats the water until it comes to a boil. Additionally these machines typically have to restore their pressure between cups, which requires time and energy.

Many espresso machines make use of the rotary or vibration pump, with a vibrating model using a rotating disc that generates the pressure and the rotary model pushing hot water through the grounds at high speed. Both machines can produce excellent espresso, however rotary machines are quieter, more durable and less likely to break.

The Boiler

The boiler is the one that makes the water warm to the ideal temperature for extraction. The steam that is produced is then directed to the portafilter, which is a container for espresso grounds. The steam is then channeled into the cup. During this process the steam is able to create enough pressure to push the grounds of the coffee espresso machine through. This creates a layer crema on top. This is one of the hallmarks of a great espresso.

There are three types of Portable Espresso Machine Compatible with NS Pods - WACACO makers, which differ in the type of pump they use and the degree of heat that the espresso is. There are also different ways in which the brew can be controlled, as well as the size of the cup the machine can produce.

The earliest espresso machines were steam type. They utilized only one boiler to make steam and brew, however, the pressure they could generate was low - only two bars of atmospheric pressure maximum. The coffee tasted bitter and burnt. This is the reason Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most popular espresso machine is a semiautomatic one with an electric pump. These are what people imagine when they imagine an espresso machine. With a semi-automatic machine, you must grind the beans and tamp them by hand. The pump provides regulated water flow and pressure. This is an excellent compromise between human touch and the mechanized quality.

The Filter

Espresso machines usually use filters that separate the grounds of the coffee from the hot water. The filter is also an essential component of the machine's temp control, since it stops overheating.

Filters also aid in flavor since it allows for a longer flowering phase. This allows the beans to let their nuances out, and also allows for better extraction.

It is important to remember that even the most efficient filter can produce a bad cup of coffee. The quality of the beans, and the extraction, are still crucial.

It's in this area that the magic happens. This is the reason why espresso tastes so delicious. The grouphead (also known as the brewhead) is where you place the portafilter - the thingy that you use to put the grounds of coffee into while making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to create steam. The steam then pushes hot water through the grounds of the coffee under pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. However, they are limited in their ability to produce the perfect brewing conditions as they only operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

In recent years, espresso machines driven by compressed air-pump are becoming increasingly popular. They make use of an air compressor to force hot water through the ground, and are more mobile than steam-driven electric espresso machines.