Setting the right grind is essential for a delicious, aromatic coffee drink. In the following, we explain which grind is optimal for a fully automatic coffee maker and why this is so.
How does a fully automatic coffee maker work?
A fully automatic coffee machine works like an espresso machine: the ground espresso powder is fed to the brewing group, compressed and then water is forced through at 9 to 10 bar. The contact between water and espresso powder is correspondingly brief, and this is precisely where the right grind comes into play.
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The optimum grind for each coffee machine
Since the water is only in contact with the coffee grounds for 25 to 30 seconds, the surface area of the grounds must be as large as possible so that the water can absorb as much aroma as possible. Therefore, the coffee beans must be finely ground: a grind of 2 to 3 is recommended, i.e. a fine, not very fine grind.
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Why not try it out? First set one extreme, brew two espressos (one after the other) and then the other and brew two espressos. It is important to brew two espressos, as the first one may be distorted by coffee powder residue.
Now compare. You should notice the following result:
The coarsest setting should have produced a thin, less aromatic espresso. Here the surface area was too large and the water could not absorb enough aromas. This phenomenon is also called under-extraction.
The fine setting probably tastes much better to you, but it is probably too bitter and has a very dark crema. Here, an over-extraction has taken place: Too many flavours and thus also bitter substances were extracted.
To set the correct grind
Check which direction you have to turn to grind the coffee beans finer or coarser. If in doubt, try it out as described above. The grind should be about a quarter away from the finest setting. So, for example, if there are five settings (1- fine, 5- coarse), you should choose 2, if there are 10 settings you should choose 3, etc.