Setting the correct grinding degree is essential for a delicious, aromatic coffee beverage. In the following, we explain which grinding degree is optimal for a coffee machine and why it is.
How does a coffee machine work?
A coffee machine works like an espresso machine: The ground espresso powder is sent to the brewing group, compressed and then chased through with 9 to 10 bar water. Accordingly, the contact between water and espresso powder is short and that's where the right degree of grinding comes into play.
The optimal grinding degree per coffee machine
Since the water is only in contact with the ground coffee for 25 to 30 seconds, the surface of the flour must be as large as possible, so that the water can absorb as many flavors as possible. Therefore, the coffee beans must be finely ground: Recommended is a grind of 2 to 3, so a fine, not very fine grinding.
Give it a try: First set one extreme, brew two espressos (one after the other) and then brew the other and brew two espressos. It is important to make two espressos, as the result may be falsified by even coffee pulp residues.
Now compare. The following result should be noted:
The coarsest setting should have produced a thin, low-aromatic espresso. Here the surface was too big and the water could not absorb enough flavors. This phenomenon is also called sub-extraction.
The fine setting may taste much better, but it is probably too bitter and has a very dark crema. Here an over-extraction took place: Too many aromas and thus bitter substances were extracted.
To set the correct grinding degree
Check which direction you need to turn in order to finer or coarser the coffee beans. If in doubt, try it out as described above. The degree of grinding should be about one quarter of the finest setting. So if it is e.g. five settings are (1- fine, 5-coarse), you should choose the 2, with 10 setting options, the 3, etc.
The most important thing: Try the coffee after your setting! After all, not the theoretically optimal setting counts but your personal taste. Is the coffee too bitter for you? Then you should set the grinder a bit coarser. If the coffee is too thin for you, then it must be something finer.