How Does Machine Espresso Work?

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

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

The Group Head

The group head is the portafilter that is inserted when you are making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the extraction. There are many different types of group heads each with its own advantages and disadvantages. Some are specifically designed for stability in temperature, while others are built to handle pre-infusion. Others are made to control the lever. Some include a mix of features, such as the E61, which is the standard choice for many baristas because of its ability to offer multiple perks in a single package.

As you can see from the image above, the group head is fitted with several notches. It is possible to place your portafilter inside these notches, and then turn the head around to secure it. There is also a gasket made of rubber that resides inside the notches to help create the seal when you insert your portafilter into the machine. The notches permit precise placement of the portafilter. This is crucial to ensure an efficient extraction.

The group head is not just able to allow you to place your portafilter easily however, it also keeps the same temperature. This is accomplished by cycling hot water around the portafilter and through the brew basin, ensuring the temperature is always right for extraction. This is important, as even a few degrees can mean the difference between excellent and great espresso.

The Pump

The motorized pumps in espresso machines that rotate provide the nine atmospheric bars of pressure required to extract espresso. This differs from manually operated piston machines that employ a lever. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be less expensive than piston-driven machines and tend to last longer. However, both types of machines can get damaged through overuse and lack of cleaning. They also add mechanical complexity, which can result in the cost of even the most basic models.

Certain mini espresso machine machines remove the pump entirely and use steam pressure to brew espresso. The disadvantage of this is that the boiler that produces steam also increases the temperature of the water to the point of boiling which could lead to over-extraction. In addition these machines are often required to restore their pressure between cups, which takes time and energy.

Many espresso machines make use of either a rotary or vibration pump, which has a vibration model that uses a vibrating disc that generates the pressure and the rotary model pushing hot water through the grounds under high speed. Both machines produce great espresso however rotary machines tend to be more quiet, durable and less likely to break down.

The Boiler

The boiler is the part that heats water to an ideal temperature to extract. The resulting steam is then transferred to the portafilter that contains the ground espresso coffee, and gets funnelled down into the cup. The steam is able to create enough pressure to push the coffee grounds through. This results in a layer of crema that is then poured over. This is one of the main characteristics of a good italian espresso Machines.

There are three kinds of espresso makers, which differ in the type of pump they employ and how hot the brew is. There are different ways that the brew can be controlled and the size of the cup that the machine can produce.

The first espresso machines were steam type. They used a single boiler to make both steam and brew, but the pressure they could create was minimal - two bars of atmospheric pressure, at most. This led to the coffee tasting bitter and burnt. The modern espresso machine was invented by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso machine is a semiautomatic that has an electric pump. When people think of espresso coffee machine with milk frother machines, they envision these machines. Semi-automatic machines require you to grind and tamp the beans yourself, but the pump regulates the flow of water and pressure. This is an excellent combination of human control and mechanized consistency.

The Filter

Espresso machines typically use a filter that separates the grounds of the coffee from the hot water. The filter is also an essential component of the machine's temp control, as it helps prevent overheating.

It also improves flavor, as a filter allows for a longer bloom time. This allows beans to let their nuances out and provides the chance for better extraction.

However, it is important to keep in mind that even a top filter can make a terrible cup of coffee as the quality of the beans and extraction are crucial.

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

In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam, which then pushes the hot water through the grounds under high pressure. These machines are cheaper and easier for the owner to maintain than pumps-driven models. They are however limited to create the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

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