How Does Machine Espresso Work?

Machine espresso coffee machine with milk frother; Full Posting, employs precise pressure and amazing filter technology to make the delicious coffee we enjoy. How does it work exactly?

In order to make espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However it is the pressure that makes the main difference.

The Head of the Group

As 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 the extraction. There are many different types of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, while others on pre-infusion features, and others are designed to control the lever. Some come with a combination of both, such as the E61. This is a favorite among baristas since it provides multiple advantages in one package.

As you can see from the image above the group head is equipped with several notches. The portafilter is placed in these notches and then twist the head to lock it. A gasket made of rubber is placed in the notches to create a seal when you insert your portafilter. The notches permit an exact placement of the portafilter. This is essential for an efficient extraction.

The group head does not just allow you to put in your portafilter easily, but it also maintains the temperature at a constant level. This is accomplished by cycling hot water around the portafilter and through the brew-basket, making sure that the temperature is constant to extract the coffee. It is important to remember that even a few degree differences can make the distinction between a great and a great espresso.

The Pump

The motorized pumps that are used in espresso machines that rotate provide the nine atmospheric bar pressure required for espresso extraction. This differs from manually operated piston machines that employ a lever. The pressure is created by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pushed through the ground coffee inside the group head.

Pumps tend to be cheaper than piston-driven machines, and tend to last longer, however both types of machine can degrade with overuse and insufficient cleaning. Pumps are also more complex mechanically, and can add to the cost of even simpler models.

Some espresso machines remove the pump entirely and utilize steam pressure to make espresso. This can cause over-extraction because the boiler that makes steam also heats the water to boil. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

Many espresso machines utilize an rotary or vibrating pump, with a vibrating model using a vibrating disc to create the pressure, and rotating models that push hot water through the grounds at high speed. Both types of machines are capable of producing excellent espresso, however rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is used to heat the water to a temperature that is ideal for extraction. The steam that is produced is then directed to the portafilter, which contains the espresso coffee grounds. It is then pumped into the cup. During this process, steam creates pressure that pushes through the grounds of the coffee. This results in a layer of crema on top. This is one of the main characteristics of a good espresso.

There are three kinds of espresso makers. They differ in the kind of pump they use and how hot the coffee is. There are also different ways that the brew can be controlled as well as the size of the cup the machine is capable of making.

The earliest espresso machines were steam type. The first espresso machines were steam types. This resulted in the coffee tasting bitter and burnt. This is the reason why Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most well-known espresso machine is a semiautomatic that has an electric pump. These are the things people think of when they think of an espresso machine. Semi-automatic machines require you to grind and tamp the beans on your own while the pump controls the flow of water and pressure. This is a great compromise between the human touch and the mechanized accuracy.

The Filter

Espresso machines typically use a filter that separates the grounds of coffee from hot water. The filter is also an essential part of the temperature control system, as it prevents the machine from overheating.

It also aids in flavor, since a filter can allow for a longer bloom time. This helps the beans to release their nuances and gives an opportunity to improve extraction.

It is important to remember that even the finest filter can make a bad cup of coffee. The quality espresso machine of the beans, as well as the extraction, are still crucial.

It's here that the magic occurs. This is what makes espresso taste so good. The grouphead (also known as the brewhead) is where you put the portafilter, which is the thingy that you put the coffee grounds in, when making espresso.

Steam-driven espresso maker for home machines make use of hot water heated in an airtight container to produce steam. The steam then pushes hot water through the coffee grounds under high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. However, they are limited in their ability to provide the perfect brewing conditions as they only operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.

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