9 . What Your Parents Taught You About Machine Espresso

How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and incredible filter technology to produce the perfect cup of coffee. How exactly does it work?

To make espresso hot water is pushed under 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 put in when making espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure that results from the extraction. There are a variety of group heads each with their own advantages and drawbacks. Some are designed for the stability of temperature while some are specifically designed to handle pre-infusion. Some are designed to control the lever. Some include a combination such as the E61. This is a favorite among baristas because it offers multiple advantages in one package.

As you can see in the image above, the group head is fitted with several notches. You can place your portafilter into these notches and twist the head to lock it. There is also a gasket made from rubber which is located inside the notches to help create a seal when you insert your portafilter into the machine. The notches on the head permit an exact placement of the portafilter, which is vital to ensure a consistent extraction.

Apart from allowing you easily connect your portafilter, the group head is responsible for maintaining a consistent temperature. It does this by cycling hot water through the brew container and around the portafilter to ensure that it's always at the right temperature for extraction. It is important to note that even a tiny variation can mean the difference between a good and a great espresso.

The Pump

The motorized pumps that are used in espresso machines rotary provide nine atmospheric bar pressure that is required to extract espresso. This is different from manual piston machines that rely on a lever. The pressure is created by pumping water through a heat exchanger and then through the ground coffee.

Pumps are generally less expensive than piston-driven machines, and they tend to last longer, but both types of machine can become damaged due to excessive use and poor cleaning. They also add mechanical complexity that can lead to an expensive price for even the simplest models.

Certain espresso machines do away with the pump entirely and utilize steam pressure to make travel espresso maker. The drawback of this is that the same boiler that produces steam also increases the temperature of the water to the point of boiling which could lead to excessive extraction. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

A large majority of italian espresso machines machines employ an rotary or a vibration pump. A vibration model employs a rotating disk to generate pressure, while a rotary model pushes hot water through the ground at a fast speed. Both machines can make great espresso but rotary machines are more stable, quieter and less likely to fail.

The Boiler

The boiler is the component that heats water to an optimal temperature for extraction. The resultant steam then reaches the portafilter which holds ground espresso beans and gets funnelled down into the cup. During this process the steam generates enough pressure to push the grounds of coffee through. This results in a layer crema that is then poured over. This is one of the main characteristics of a good espresso.

There are three types of espresso makers. They differ in the type of pump they use and how hot the coffee is. There are various ways to control the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam-based. They employed a single boiler to make steam and brew, however the pressure they were able to create was minimal - two bars of atmospheric pressure maximum. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso machine is a semiautomatic model with an electric pump. These are the images people have when they think of an espresso machine. With a semi-automatic espresso machine, you have to grind the beans and then tamp them by hand. The pump controls the flow of water and pressure. This is an excellent solution that combines human control with mechanized consistency.

The Filter

Espresso machines typically have a filter that separates the coffee grounds from the hot water. The filter is also a vital part of the temperature control system, because it stops the machine from overheating.

It also helps with flavor as a filter lets you enjoy a longer bloom time. This allows the beans to let their nuances out, and also allows for better extraction.

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

It's in this area that the magic occurs. This is the reason why espresso machine coffee tastes so good. 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 when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to produce steam, which is then pushed through the grounds at a high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.

In recent years, top espresso machines machines driven by compressed air-pump have become increasingly popular. They use an air compressor to push hot water through grounds and are significantly more portable than steam-driven electric machines.