How Does Machine Espresso Work?

Machine espresso employs precise pressure and mind-blowing filter technology to make the coffee we love. 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 pressure is the primary difference.

The Group Head

The group head is the portafilter that you place in the espresso maker when making it. It disperses water into the portafilter and regulates the pressure of extraction. There are a variety of types of group head each with its particular advantages and disadvantages. Some are designed to provide stability of temperature while others are specifically designed to handle pre-infusion. Some are designed to control the lever. Some include a combination like the E61. This is a preferred choice for baristas due to the fact that it has multiple advantages in a single package.

As you can see from the photo above, the group head is equipped with several notches. The portafilter is placed in these notches, then turn the head around to secure it. There is also a rubber gasket that resides inside the notches, which helps create an airtight seal when you insert your portafilter into the machine. The notches on the head permit an exact location of the portafilter which is crucial for an even extraction.

In addition to allowing you easily connect your portafilter, the group head is also responsible for maintaining a consistent temperature. This is accomplished by cycling hot water around the portafilter, and through the brew basin, ensuring that the temperature is constant to extract the coffee. This is important because just a few degrees could be the difference between a good and excellent espresso.

The Pump

Contrary to manual piston machines which use a lever to pressurize water, the rotary espresso machines use motorized pumps that provide the nine atmospheric bars of pressure required for espresso machines home extraction. The pressure is created 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 tend to be less expensive and last for longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of excessive use and inadequate cleaning. Pumps are also more complex mechanically, and can add to prices of even most basic models.

Some espresso machines use steam pressure instead of a pump to brew espresso. This can result in over-extraction because the boiler that produces steam also causes the water to boil. Additionally these machines are often required to rebuild their pressure between cups, which requires time and energy.

Many barista espresso coffee machine machines make use of the rotary or vibration pump, with a vibrating model that uses a vibrating disc to create the pressure, and a rotary model pushing hot water through the grounds at high speed. Both types of machine are capable of producing excellent espresso, however Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler makes the water warm to the ideal temperature to extract. The resulting steam reaches the portafilter which holds the ground espresso coffee and is then funneled down into the cup. The steam is able to create enough pressure to push the coffee grounds through. This creates a crema on the top of the espresso. This is one of the hallmarks of a great espresso.

There are three types of espresso machines, each with different pumps and the temperature of the brew. There are many ways to control the amount of brew, as well as the size of the cup that can be made by the machine.

The first espresso machines were steam-type. They used a single boiler to make steam and brew, however the pressure they were able to generate was low - only two bars of atmospheric pressure maximum. This led to the coffee and espresso machine tasting bitter and burnt. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most well-known espresso machine uk machine is a semiautomatic model with an electric pump. When people think of espresso 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 human control and mechanized accuracy.

The Filter

Typically, espresso machines utilize filters that separate the coffee grounds as they pass through the hot water. The filter is also an important element of the temperature control system, as it keeps the machine from overheating.

Filters also aid in flavor since it allows for the beans to flower for a longer period of time. This helps the beans to release their flavor and gives the chance for better extraction.

It is important to keep in mind that even the best filter can produce a bad cup of coffee. The quality of the beans, and the extraction process, remain vital.

This is where the magic happens, it's what makes espresso taste good. The grouphead (also called the brewhead) is where you put the portafilter, which is the thingy used to place the grounds of your coffee into when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight container to create steam. Steam is then pushed through the grounds at high pressure. These types of machines are generally cheaper and easier to maintain than pump-driven models. They are however limited 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 compressor have become increasingly popular. They utilize an air compressor to force hot water through the ground. They are also more mobile than steam-driven electric espresso machines.