How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the delicious coffee we enjoy. But how exactly does it work?

Espresso is produced by pushing hot water under 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 group head is the portafilter you insert when brewing espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the resulting extraction. There are many different kinds of group heads each with its own advantages and drawbacks. Some are designed for the stability of temperature while some are designed to handle pre-infusion. Others are built to control the lever. There are also some that include a mix of features, like the E61, which is considered to be the most popular among baristas due to its ability to offer multiple benefits in one package.

As you can see in the photo above the group head comes with many notches in which you can place your portafilter and twist it by hand to lock it in. There is also a gasket made from rubber in the notches and 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 vital for an efficient extraction.

In addition to allowing you easily insert your portafilter, the group head is also responsible to ensure that the temperature remains even. This is accomplished by cycling hot water around the portafilter and through the brew-basket, ensuring that the temperature is constant to extract the coffee. This is important, as even a few degrees can make the difference between good and excellent espresso.

The Pump

Motorized pumps in rotary espresso machines supply the nine atmospheric bar pressure needed to extract espresso. This is different from manual piston machines which use levers. The pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger prior to being shot through the ground coffee in the group head.

Pumps are typically less expensive than piston-driven machines and tend to last longer, however both types of machines could degrade with overuse and insufficient cleaning. Pumps are also more complicated mechanically, which can raise the price of even the 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 causes the water to boil. Additionally the machines often have to rebuild their pressure between cups, which takes time and energy.

Many espresso machines make use of either a vibration or rotary pump. A vibration model employs a vibrating disk to generate pressure, while a Rotary model pushes hot coffee through the ground at a fast speed. Both machines can produce excellent espresso, however rotary machines are more quiet, durable and less likely to break down.

The Boiler

The boiler makes the water warm to the right temperature for extraction. The steam that is produced reaches the portafilter that contains the ground espresso coffee, and is then pumped down into the cup. During this process, the steam creates pressure and pushes through the grounds of the coffee. This creates a crema on top of the espresso. This is a hallmark of a good espresso.

There are three types of espresso makers, and they differ in the type of pump they use and how hot the brew 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 first espresso machines were steam-types. The first espresso machines were steam types. This resulted in the coffee tasting bitter and burnt. This is why the Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most well-known espresso maker is a semi-automatic device with an electric pump. These are the things people think of when they think of an espresso maker. With a semi-automatic espresso machine, you have to 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 the mechanised consistency.

The Filter

home espresso machine machines typically have filters that separate the grounds of coffee from hot water. The filter is also an essential component of the machine's temp control, since it helps to prevent overheating.

A filter also improves flavor since it allows for a longer flowering period. This allows beans to release their flavors and provides an opportunity to improve extraction.

However, it is important to keep in mind that even a great filter can make a terrible cup of coffee, since the quality of the beans and extraction is still vital.

It's in this area that the magic happens. This is what makes espresso taste so delicious. The grouphead, sometimes referred to as the brew head, is the place where the portafilter (the thingy you put the coffee ground into) is placed when you're making espresso.

Steam-driven espresso machines make use of hot water that is heated inside an airtight container to make steam. The steam then moves hot water through the coffee machine espresso grounds under high pressure. They are less expensive and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the ideal brewing conditions, as they only operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

In recent years, compressed air-driven espresso machines have been gaining popularity. They use an air compressor to push the hot water through the grounds and are significantly more portable than electric steam-driven machines.