How Does Machine Espresso Work?

The machine espresso is made using precision pressure, and filter technology that is mind-blowing to create the coffee you enjoy. What exactly is it?

buy espresso machines is made by forcing hot water at 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 you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter and controlling the pressure of the extraction. There are several different types of group heads, each with their distinct advantages and drawbacks. Some are designed for temperature stability while others are specifically designed to handle pre-infusion. Others are made to control the lever. Some include a mix of features, such as the E61 that is the most popular choice among baristas for its ability to offer multiple benefits in a single package.

As you can see from the picture above the head of the group is equipped with several notches. It is possible to place your portafilter in these notches and then twist the head to lock it. There is also a gasket of rubber that resides inside the notches and helps to create the seal when you insert your portafilter into the machine. The notches on the head permit an exact positioning of the portafilter which is vital to ensure a consistent extraction.

In addition to allowing you to easily insert your portafilter, the group head is also responsible for maintaining an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is constant to extract the coffee. This is vital, because even a few degrees can make the difference between a excellent and great espresso.

The Pump

The motorized pumps that are used in rotary espresso machines provide the nine atmospheric bar pressure needed for espresso extraction. This differs from manually operated piston machines that employ levers. The pressure builds by removing tap water from a reservoir, and pumping it through a heat exchanger prior it is shot through the ground coffee in the group head.

Pumps are typically less expensive than piston-driven models, and they tend to last longer. However, both types of machines can degrade with overuse and insufficient cleaning. Pumps are also more complicated mechanically, and can add to prices of even simplest models.

Certain espresso machines utilize steam pressure instead of a pump in order to brew discount espresso machines. This could lead to over-extraction since the boiler that makes steam also causes the water to boil. Additionally these machines are often required to restore their pressure between cups, which requires time and energy.

A large majority of espresso machines employ a rotary or vibration pump. A vibration model makes use of a vibrating disk to generate pressure, while the circular model pushes hot liquid through the ground at a rapid speed. Both types of machine are capable of producing excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is what makes the water warm to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter containing the ground espresso coffee, and gets funnelled down into the cup. In this process, the steam creates pressure to push through the coffee grounds. This results in a layer of crema on top. 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 a variety of ways in which the brew can be controlled and the size of the cup that the machine is capable of making.

The first espresso machines were steam types. They used one boiler to make both brew and steam, however, the pressure they could produce was very low - just two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. This is why the Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most commonly used espresso machine is a semiautomatic model 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 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 consistency.

The Filter

Typically, espresso machines utilize a filter to separate out the coffee grounds as they pass through the hot water. The filter is also a vital element of the temperature control system as it prevents the machine from overheating.

A filter also improves flavor, as it permits a longer flowering phase. This lets the beans release their nuances, and allows for a better extraction.

However it is crucial to keep in mind that even a good filter can produce a bad cup of coffee, because the quality of the beans and extraction is crucial.

It's here that the magic takes place. This is what makes espresso taste so delicious. The grouphead (also known as the brewhead) is where you place the portafilter - the thingy that you use to put the grounds of coffee into while making espresso.

Steam-driven espresso machines make use of hot water that is heated inside an airtight container to create steam. The steam then pushes hot water into the grounds of coffee at high pressure. These kinds of machines are typically less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to provide 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, compressed air pump-driven espresso machines have been gaining popularity. They utilize an air compressor to force the hot water through the grounds and are significantly more portable than electric steam-driven machines.