The calibration of the grinder is an important phase in the preparation of coffee, either for an espresso or any other type of preparation. In this article, we will mention mainly about espresso, but this does not diminish the importance of an adapted version depending on whether you will use a mocha coffee, plunger or filter. The first thing to know is that the mills leave the factory with a medium setting; it does not normally suit your needs.
OPTIMAL TIME EXTRACTION
It takes between 25 and 30 seconds to extract 40 ml espresso and about 20 seconds for a 20 ml ristretto for each the using of a single dose of coffee (which can vary from 7 to 8 g).
If the extraction is faster, there will not be enough flavors extracted and taste will be bland. When the grind is too rough, the water passes quickly. Therefore, it is necessary to grind coffee finer. If the extraction takes more than 30 seconds, the coffee will be bitter.
If the grind is fine, it will be more difficult for water to penetrate and pass through the coffee grounds.
CONSISTENCY OF MILLING
See the saucer or small container under the spout of the grinder and watch the milling obtained. This will start to form small heap. If it does not form these small piles and it seems to be more grainy than mealy, the coffee is not ground finely enough.
AND WHAT TIME IN?
The observation that you have made previously will also give you an idea of the humidity of the surrounding air, supposing that the air humidity directly affects milling. Specifically, the ground coffee absorbs moisture from the air; it’s one of the reasons why you have to keep the coffee beans in an airtight jar. In humid weather, the grind will be compacted and forms small piles.
If the weather is dry, grind coffee will be finer. What a mistake without saying that if you want to maintain consistency in the preparation of espresso, you should take a glance eye on the weather. It will tell you if you need to adjust the grinder setting.
It also a mistake without saying that all the coffee beans do not have the same residual moisture (this depends on the variety, the type of crop, soil, drying and roasting). So you can get two different grinds in the same day using two separate cafes without touching the crusher setting. You should know this and take it into consideration when you decide to change the type of coffee.
SIZING OF MILL
Load and pack a dose of 1 cup of coffee in the filter and insert the filter holder in the machine. Then run the extraction and start the timer at the same time.
If the grind is correct, the flow will start after about 4 seconds. The flow is steady and constant, and the cream will be golden brown.
If the grind is too coarse, the flow will begin in less than 3 seconds and will be substantially rapid and irregular. There will be little cream, pale and it will dissolve quickly. If the grind is too fine, the flow will not start until 5-6 seconds, the cream will be dark and the drink is full of bitterness. Then the milling may be easily regulated either by a button or by turning the collar at the base of the grain bin, either by turning the grain bin, depending on the models.
The adjustment direction can also vary depending on the model. For most mills, the rotation in the direction of clockwise will make the finer grind, and rotation in the opposite direction of clockwise will give a coarser grind. With the new calibration, retest with an espresso and repeat the process until you have the desired result.
Note that there are always a few grains that remain between the wheels of the mill, the adjustment will be effective only when these grains have been removed, so it will cause some loss, be aware. On the other hand, when you want to set a finer grind, it is always advisable to do during milling to avoid damaging the system of wheels. You can do so by against the judgment to obtain a coarser grind, inconsequential to the haystacks.
An aside on pressurized filters
We would like to make an important clarification if you use an espresso machine equipped with pressurized filters.
The entire process described above applies when preparing espresso with conventional filters (perforated metal basket), but if the filters are pressurized (also called filter pressurization chamber), the milling settings may differ.
For the simple reason that the filter pressurization chamber (the double bottom which will increase the strength of opposition to the passage of water) provides a creamy coffee even with a filter coffee. Nevertheless, even if the cup gives the impression of a perfect espresso, the taste will not be fine if the grind is too coarse. Proceed as explained above; the final criterion is your assessment of the last cup.