In order to drink coffee, it is essential to grind the beans.
The grind should not be taken for granted, as it greatly affects the final result of the extracted coffee!
Find out why now, thanks to this article!
Let’s start with a somewhat more boring part, but important for understanding how much the grind affects the coffee extracted.
So: grinding increases the extraction surface area, that is, it increases the contact surface area between coffee powder and water. This allows more soluble solids to be transferred into the drink.
In addition, the aromatic substances formed during roasting are trapped in the cells of the coffee bean. Only by breaking them can we free them.
What does it mean? Look at the image below and it will be very clear.
Let us imagine that we have ground coffee at these three levels:
- The first image on the left shows a fine gr ind and each square represents a small grain of the grind;
- The one in the center is a medium grind;
- In contrast, the one on the right is a broad grind;
- Blue, on the other hand, represents water .
Imagine running water through these elements for 120 seconds:
- In the first case, the coffee would be over-extracted, because the hot water would wrap around each individual bean for a long time and manage to penetrate deeply, as well as “burn” the outermost part, which remained too much in contact at the high temperatures;
- In the second example, on the other hand, given the larger size of the mince, the water in 120 seconds would slowly, but only, manage to get to the heart of the mince extracting all the solid solubles at the right point;
- In the latter case, on the other hand, the water in the 120 seconds would not even make it to the center of the particulate because it is too deep relative to the surface of the particulate, thus making the drink under-extracted.
An under-extracted drink will be flatter, watery, acidic and astringent; conversely, an over-extracted drink will be more bitter, with hints of burning.
With the same image in mind, let’s take two more examples:
1. If we ran the water for a shorter time, so for about 25 seconds, as in the case of extracting an espresso coffee: what would happen? Water flowing for less time needs more contact surface area, so fine grinding will be needed to be able to extract everything it needs in just 25 seconds. While in the other two cases the drink would be under-extracted.
2. What if we run the water for 4 minutes instead? A wide grind will be needed to avoid over-extracting the drink.
So do you understand why grinding is critical, and each extraction method needs a specific level of grinding?
In general, I can give you tips on grind size by type of extraction, keeping in mind that 1 micron is equal to one thousandth of a millimeter:
- French Press and Cold Brew require a very wide grind, that is, between 800 and 1000 microns. In other words, of a size between coarse salt and fine salt;
- Filter coffee automatics and other percolation methods, such as Clever, Chemex, and V60, need a medium to large size, between 500 and 700 microns. Like small grains of sand or fine table salt;
- Other methods that have higher pressure than atmospheric pressure, such as the Moka, Aeropress, or Syphone, need a medium-fine grind, about 400-600 microns;
- Then we find the right grind for espresso, which is fine, between 200 and 300 microns, similar to very fine sugar;
- Finally we have the grind for Turkish-style coffee, that is, extra-fine, under 200 microns.
With this I am not asking you to measure the size of your mince in microns because, one does not have the proper tools, it would be impossible! But at least now you have good reference points.
Indicate in your order what type of machine you use at home, and we’ll take care of finding the right grind! DISCOVER MORE >>
I wanted to conclude with another cue.
Weathering, i.e., air, humidity, heat and light, spoils coffee.
In addition, the ground grain is much more sensitive, compared to the whole grain.
Remember how I told you at the beginning of the article that grinding is to release the aromatic substances formed during the roasting phase?
In fact, it is estimated that about 60 percent of the aromas in coffee dissipate into the air just 15 minutes after grinding, if the coffee is poorly stored.
This is why I recommend that you buy coffee beans and grind them only at the time of use. However, if you do not have this option, pay attention to the type of package you purchase.
The most advanced technology currently consists of:
- A non-transparent package so that the mince does not come into contact with light;
- Sealed so that it will not be oxidized by contact with air and/or moisture;
- With a one-way valve, in a controlled nitrogen atmosphere, to allow the coffee to continue to degas and thus let gases, especially carbon dioxide, continue to be naturally produced from the package.
You can see these packs at caffeernani.com, selected specifically to allow you to get coffee as fresh as freshly ground.