Every bartender knows that in order to get the perfect espresso, delicious and balanced, it is essential that the beans are ground to the right fineness. If they are ground too finely or, on the contrary, too coarsely , this is not a satisfying result for the customer: in the first instance the coffee could have a bitter taste, while in the second, it will not be intense enough.
What should you keep in mind then, so as not to commit errors in this important phase of the work “behind the bar” is how to regulate the coffee grinding. Here’s what you need to know about how the coffee grinder works and which steps you need to take to set it up correctly.
How the coffee grinder-dispenser works
The tool you need to pulverize the roasted coffee beans is the coffee grinder. Its main components are a hopper that the beans are poured into, the grinders driven by an electric motor and a ferrule for regulating the grinding.
The process takes place in the following way: the coffee beans contained in the hopper are channeled towards the grinding cup; the steel grinders rotate at high speed and crush the beans. At this point, the dispenser collects the coffee powder and gives out the necessary quantity.
The coffee grinder can be of two different types: with flat grinders or with conical grinders. Let’s see what the differences are.
In the coffee grinder with two flat grinders, these are positioned one on top of the other and they are identical and opposing: the first, (the upper one) is fixed and the second is adjustable, and is the one which rotates, driven by the crankshaft. The beans are ground when they are between the two grinders, which push them out towards the edges and crush them to the required size. This type of coffee grinder, although very common and generally inexpensive, tends, however, to overheat the coffee, but the grinding fineness obtained is more homogeneous. It is more suitable for lower levels of coffee consumption, not exceeding 4 kg a day and its grinders should be replaced after maximum 500 kg of coffee ground.
The coffee grinder-dispenser with conical grinders, however, has two grinders one inside the other. The distance between the two can be regulated to obtain different levels of grinding fineness and this type of grinding, that uses the force of gravity, does not create problems of overheating, because the number of revolutions of the grinders is low (around 400-500 a minute). This type of machine is recommended where there is large daily consumption of coffee.
After the grinding, the coffee falls into the dispenser, which can also be regulated and filled manually or automatically: in this second case, when the level of coffee powder drops, the machine is automatically activated.
Why the grinding is important: over-extracted coffee and under-extracted coffee
As you know, the quality of the final product depends on the grinding fineness of the coffee powder : if we take for example an espresso, the most frequently prepared drink in a bar, which has an extraction time of around 25 seconds, we talk about under-extracted coffee when the grinding is not fine enough and the water passes through the coffee powder too quickly and for too little time. Coffee prepared in this way will have an uneven cream on top which separates, it will have an excessively light color and the flavor will be “watery”.
If, on the other hand, the powder is ground too finely, the coffee will be over-extracted: in this case, the water passes through the coffee powder too slowly. The result is a darker drink with a bitter taste.
Coffee grinding in the bar: how to regulate it
Based on the type of coffee we are going to serve, we will need a different grinding of the beans. For example, for the perfect espresso, the coffee powder needs to be very finely ground, whereas if we are using the Neapolitan coffee pot or a filter coffee pot you will need medium-fine coffee powder; for strainer machines or with a plunger, on the other hand, the grain should be medium-large.
These are the steps to follow, regardless of whether you use a grinder with flat or conical grinders, for setting the espresso grinding. To get the settings of the coffee grinder-dispenser just right, you need to have a timer handy, and use a double portafilter (which contains between 14 and 20 g of coffee), rather than a single one. This is because the greater the amount of coffee ground, the better the quality of the extraction.
- First of all, prepare two espressos, checking the extraction time carefully.
- If the extraction lasts less than 25 seconds, move the regulation ring towards the finer setting. Grind a double dose, throw it away to be sure that you get the right grinding fineness from that point on, and grind more coffee.
- Prepare an espresso, checking the extraction time (which must be between 23 and 27 seconds) with the timer and assess the quality both in terms of flavor and visual aspect.
- If the coffee does not have a sufficiently good look or aroma, move the regulation ring again and grind more coffee powder, more finely if the previous espresso was under-extracted , or more coarsely if it was over-extracted.
So, the grinding, if done in the correct way, guarantees the quality of the coffee served to the customer. Of course, it goes without saying that, the skill and experience of the barista is also important. Then there are also small, but nonetheless, essential details which should not be forgotten: the coffee grinder must be carefully cleaned every evening, and the general wear and tear of the grinders should also be regularly checked since it may affect the constancy with which the machine can vary the grinding fineness, and potentially alter the quality of the product. Finally, you should not grind large quantities of coffee which you are not going to use immediately: in ground coffee, the surface area in contact with the air increases enormously compared to that of beans, and the aromatic substances will be dispersed more rapidly.
Have you had any difficulties in regulating the grinder settings in your bar ? For further details and information you can refer to our consulting and assistance service that Filicori Zecchini reserves for its clients.