All about the espresso machine

Or almost

Of all the ways to make coffee, the most famous and at the same time the most unknown is with the espresso machine. Although most of us do not have an espresso machine at home (but it is never too late if the vice is strong), in the usual bars it is the only coffee that is prepared together with a kind of powder that we are not sure is coffee.

However, despite having drunk it thousands of times, few people know what happens inside the espresso machine so that those ground beans and water end up forming a drink with a certain density and a lot of flavor power.

In fact, in addition to coffee and water, the espresso recipe requires another ingredient. Don't you know? If you are thinking of buying an espresso machine, we recommend that you sign up for The Coffee Academy's espresso workshop to gain an in-depth understanding of how an espresso machine works.

This other ingredient is pressure. Measured in bars, the pressure is responsible for generating the extraction of the substances contained in the ground coffee with the water. And what generates this pressure? A pump. But let's go step by step.

Water

The first thing, as always, is the water. Normally, professional coffee makers are connected to the mains, as if it were just another tap. In addition, in many places, such as the coffee shops at NOMAD, we use a filter that allows us to know more about the water that comes through the pipes that day, since it always varies slightly, and to adjust some parameters so that the quality of our coffee and its organoleptic properties are not compromised. We use a reverse osmosis filter to clean the water from the network of impurities and demineralize it, as well as another filter to remineralize it according to the parameters we set.

The pump

The pressure pump is the part of the espresso machine that will generate the necessary bars, i.e. 9 bars or 130 PSI (pound per square inch), although this is not a rigid standard. For reference, Champagne is bottled at 3.5 bars of pressure, bicycle tires between 8 and 9 and car tires between 2 and 2.5 bars.

Types of machines

Within the espresso machines capable of generating high pressure, there are automatic, semi-automatic and super-automatic machines.

- Automatic: something vital for making coffee is to be able to control the amount of water in each shot, and this machine ensures that you will always have the same grams of coffee in each cup.

- Semi-automatic: they regulate the temperature and water pressure, but the barista must control the extraction time. A good example is the Marzocco Linea Mini.

- Superautomatic: they do everything from grinding the coffee beans, depositing and tamping them in the filter holder and the whole extraction process.

There are some espresso machines that even allow higher or lower pressure at different moments of the extraction. This is interesting, for example, so that in the initial phase, when the coffee pod is not yet wet, it receives a lighter pressure to allow the coffee to expand homogeneously and achieve a more regular extraction, avoiding channeling. This can also prevent very fine coffee particles from clogging the coffee outlet and causing insufficient extraction.

On the other hand, there are also other less common methods in coffee shops, such as lever espresso machines, which work by moving down a lever that activates a piston, which allows to control the pressure during the extraction process. And also steam espresso machines, common in homes, which only generate between 1 and 1.5 bars of pressure, which is not ideal for a good shot of espresso. Steam espresso machines result in a coffee very similar to that obtained with a mocha.

Extraction

When you have an espresso machine that allows you to adjust the values, baristas get creative and play with them to achieve the recipe that they like best for a given type of coffee, whether to highlight certain flavors or others, or to achieve greater or lesser density. At NOMAD, our baristas prepare and taste all the coffees on a daily basis and modulate the recipes according to the results of each test. The espresso should be within a range of 9-10 TDS (Total Dissolved Solids) and an extraction percentage of 19 and 23%.