How Does Machine Espresso Work?

Machine espresso employs precise pressure and mind-blowing filter technology to create the coffee we love. But how exactly does it work?

To make espresso, hot water is forced under high pressure through finely best ground coffee for espresso machine coffee. The process is similar to making drip coffee. However the pressure is the major difference.

The Group Head

As the name implies the group head is where you place your portafilter while brewing espresso. It disperses the water into the portafilter, and regulates the pressure during the extraction. There are a variety of types of group head, each with their own advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion capabilities, while others are designed to control the lever. Some include a combination like the E61. This is a favorite among baristas due to the fact that it has multiple benefits in a single package.

As you can see in the image above the head of the group is fitted with a variety of notches. You place your portafilter into these notches and twist the head to lock it. There is also a gasket made from rubber in the notches, which helps create an airtight seal when you insert your portafilter into the machine. The notches on the head permit a precise placement of the portafilter, which is necessary for a consistent extraction.

Apart from allowing you effortlessly insert your portafilter the group head is responsible for maintaining an even temperature. This is achieved by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is at the right level to extract the coffee. It is important to realize that even a slight deviation can make the difference between a good and a great espresso.

The Pump

Unlike manual piston machines, which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure that are required for espresso machine coffee extraction. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior to being shot through the ground coffee inside the group head.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both kinds of machines may degrade because of excessive use and inadequate cleaning. Pumps are also more complicated mechanically, which could increase the price of even the simple models.

Certain espresso machines utilize steam pressure instead of a pump to brew espresso. The downside is that the same boiler that produces steam also raises the temperature of water until it reaches boiling, which can lead to over-extraction. In addition the machines often have to restore their pressure between cups, which requires time and energy.

Many espresso machines use the rotary or vibration pump. A vibration model makes use of a vibrating disk to generate pressure, while a Rotary model pushes hot coffee through the ground at a fast speed. Both types of machine can make a great espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the component that heats water to an ideal temperature to extract. The steam that is produced reaches the portafilter which holds the ground espresso coffee, and gets funnelled down into the cup. The steam creates enough pressure to push the coffee grounds through. This results in a whipped-up top of the espresso. This is one of the main characteristics of a great espresso.

There are three types of espresso makers, which differ in the type of pump they employ and the degree of heat that the brew is. There are different ways to control the brew as well as the size of the cup that can be made by the machine.

The earliest espresso machines were steam types. The earliest espresso machines espresso were steam-type machines. The coffee tasted bitter and burned. This is why Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most commonly used espresso and filter coffee machine machine is a semiautomatic with an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp the beans yourself, but the pump regulates the water flow and pressure. This is a great compromise between the human touch and the mechanized accuracy.

The Filter

Espresso machines usually have a filter that separates the grounds of coffee from hot water. The filter is also a vital part of the machine's temperature control, as it prevents overheating.

It also enhances flavor, as it allows for a longer bloom phase. This allows beans to release their flavors and provides an opportunity for a better extraction.

It is important to keep in mind that even the finest filter could result in a poor cup of coffee. The quality of the beans and the extraction process, remain vital.

It's here that the magic takes place. This is what makes espresso taste so delicious. The grouphead, also referred to as the brewhead, is where the portafilter (the thing you put the coffee grounds into) is located when you're making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to make steam. The steam then pushes hot water through the grounds of coffee at high pressure. These machines are less expensive and easier for the user to maintain than pumps-driven models. However, they are limited in their ability to produce the perfect conditions for brewing, since they 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 have become increasingly popular. They use an air compressor to force hot water through grounds and are significantly more portable than steam-driven electric machines.