How important is the right grinding of coffee beans?


In order to drink a coffee, it is essential to grind the beans.

The grinding should not be taken for granted, because it has a considerable impact on the final result of the extracted coffee!

Find out now why, thanks to this article!

Let's start with a bit more boring, but important to understand how the grind affects the extracted coffee.

Hence: grinding increases the extraction surface, i.e. increases the contact surface between coffee powder and water so that it is possible to transfer more soluble substances into the drink.

Furthermore, the aromatic substances formed during the roasting phase 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 everything will be very clear.


Let's imagine that you have ground the coffee at these three levels:

  1. The first image on the left shows a fine grind and each square represents a small grain of ground;
  2. The one in the center is a medium grind;
  3. The one on the right is a large grind;
  4. The 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 envelops each single grain for a long time and is able to penetrate deeply, as well as "burn" the outermost part, which has remained too much in contact at high temperatures;
  • In the second, however, given the larger size of the ground coffee, the water in 120 seconds is able to slowly reach the heart of the ground, extracting all the soluble solids at the right point;
  • In the latter case, however, the water in 120 seconds fails to reach the center of the particulate, because it is too deep, thus making the drink under-extracted.

An under-extracted drink will be flatter, watery, acidic and astringent; on the contrary, an over-extracted drink will be more bitter, with hints of burning.

Keeping in mind the same image we make two more examples:

1. If we ran the water for a shorter time, then for about 25 seconds, as in the case of extracting an espresso: what would happen? The water flowing for less time needs a greater contact surface, so a 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 let the water run for 4 minutes? A larger grind will be needed to avoid over-extracting the drink.

Now you can understand why grinding is essential and why each extraction method requires a specific level of grinding?

In general I can give you some tips on the size of the grind by type of extraction, bearing in mind that 1 micron is equal to one thousandth of a millimeter:

  • French Press and Cold Brew require a very large grind, i.e. between 800 and 1000 microns. To be clear about a dimension between coarse salt and fine cooking salt;
  • The automats for filter coffee and other percolation methods, such as Clever, Chemex and V60, require a medium-large size, between 500 and 700 microns. Like small grains of sand or fine cooking salt;
  • Other methods that have a higher pressure than atmospheric pressure, such as the Moka, the Aeropress or the Syphone, require a medium-fine ground, of about 400-600 microns;
  • Then we find the right grind for the espresso, that is fine, between 200 and 300 microns, similar to very fine sugar;
  • Finally we have the grinding for the Turkish coffee, that is extra-fine, under 200 microns.

With this I don't ask you to measure the size of your ground in microns, it would be impossible if you don't have the right tools! But at least now you have valid references.

Indicate what type of machine you use at home and we will take care of finding the right grind! FIND OUT MORE >>

I wanted to conclude with another point.

As you well know, atmospheric agents, i.e. air, humidity, heat and light, ruin coffee.

Furthermore, the ground is much more sensitive than the whole grain.

Do you remember that at the beginning of the article I told you that grinding is used to release the aromatic substances formed in roasting? In fact, it is estimated that about 60% of the aromas present in coffee are dispersed into the air after only 15 minutes from grinding, if the coffee is badly stored.

This is why I recommend that you buy coffee beans, and grind it only at the time of use. If you do not have this possibility, however, pay attention to the type of package purchased.

The most advanced technology currently consists of:

  1. A non-transparent package, so as not to let the ground coffee come into contact with the light;
  2. Sealed, so that it does not oxidize due to contact with air and / or humidity;
  3. With one-way valve, in a controlled nitrogen atmosphere, to allow the coffee to continue degassing and then let the gases out of the package, in particular carbon dioxide, which continues to produce naturally.

You can see these packages on, selected precisely to allow you to get a coffee as fresh as freshly ground. FIND OUT MORE >>

Martina Mazzoleni 

The best coffees, roasted to perfection and delivered where you want

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