There are several factors that affect the taste of our coffee. Starting from the raw material, to the roasting process, and finally to the extraction. In this final and very important step, one of the most challenging actions to take is:
The grind size
Unfortunately, this very important element of coffee extraction is still overlooked by many baristas or café owners, who often rely on technical support companies to do this job for them.
Coffee grinding
The aromatic compounds that develop inside a coffee bean during roasting are trapped within its cellular structure. By breaking the bean, we can release the aromas. Through grinding, we increase the surface area of the coffee that comes into contact with water, facilitating the extraction of aromatic compounds. In fact, the finer the grind, the more coffee surface area will be exposed during extraction.
Coffee Grinders
The coffee grinder is a very important piece of equipment in a café. It is often even more important than the espresso machine.
Thanks to the metal burrs (flat or conical), it allows you to grind the coffee bean into small particles. By adjusting the grind size, the distance between the burrs increases or decreases.
In fact, by bringing them closer together, we will achieve a finer grind size. On the other hand, by moving them farther apart, the grind size will be coarser. Each coffee grinder manufacturer has its own system for adjusting the burr distance, either manually or electronically.
Larger dials and higher numbers usually correspond to coarser grind sizes. Various models feature arrows with fine-coarse indicators to assist the barista in adjusting the grind.
For Espresso
Πριν αρχίσουμε να στήνουμε τον μύλο καφέ μας, είναι σημαντικό να έχουμε μια σαφή κατανόηση της συνταγής εσπρέσο που θέλουμε να προσφέρουμε τους πελάτες μας. Επίσης, πρέπει να έχουμε ένα θεμελιώδες εργαλείο για τη σωστή ρύθμιση της λείανσης.
A. Scale
Let’s start with the dose of ground coffee we want to use. Typically, the portafilters used in espresso machines in Italy can hold about 7 to 9 grams of coffee (14 to 18 grams in a double filter).
If you want to use higher doses, you will need to use larger filters. From this coffee dose, we will extract 25 ml of espresso in 22 to 28 seconds.
This does not guarantee that we have extracted the best possible espresso from our coffee yet, but at the very least, these are the correct parameters to ensure a balanced drink in the cup.
In fact, with shorter extraction times, we will get an espresso with a very light crema that tends to dissipate quickly, with very low body and aroma. On the other hand, with a longer contact time, it is very likely that the water will extract unwanted substances into our espresso, resulting in bitter and astringent sensations.
B. Weigh and time your espresso every morning.
In barista courses at Espresso Academy, we recommend using a scale to weigh the espresso in the cup during extraction. This allows you to be much more precise about the exact amount being extracted.
Also, a timer can be very useful (if your espresso machine is a bit more traditional and doesn’t have one!).
The volumetric parameters of the machine may be accurate if the coffee dose remains unchanged, but small variations in dosage will also affect your cup. This is due to the absorption of water by the ground coffee. In fact, more coffee = less espresso in the cup, and vice versa.
G. Finding the correct grind size
It is recommended to adjust the grind using the double espresso filter basket. In the morning, before you start making the first coffees, we recommend grinding a dose of 14 to 18 grams of coffee.
Use a dosing glass inside the portafilter until you reach the desired weight and then test an extraction. If this espresso extraction takes less than 22 seconds (with a lower espresso yield), you should adjust the grind to a “finer” setting to slow down the extraction time. Here, we increase the contact time between water and ground coffee, allowing the water to extract all the positive compounds from our coffee.
If, on the other hand, the espresso extraction takes more than 28 seconds, you should adjust the grind settings to a “coarser” level in order to speed up the extraction time. Thus, we reduce the contact time between the water and the ground coffee, preventing the water from extracting negative compounds from our coffee.
Before changing the grind size, we should always empty the grinder of any leftover coffee grounds. For this reason, during adjustments, we recommend grinding only what is needed for a single dose.
We also suggest adjusting the grind whenever we realize that our extractions no longer fall within the parameters of our recipe, something that regularly occurs throughout the day due to various factors that affect roasted coffee. Not only the humidity in the air, but also the degassing time of the coffee in the hopper and the heating of the burrs during peak hours, can be variables that influence the grind and, consequently, your espresso extraction.
