Coffee roasting with Ernani

I maestri della tostatura media

In March we started a small episodic series on all our social channels about the Roasting process.

The goal is to offer you suitable tools to understand how the roasting phase works and therefore understand the transformations of the bean, to be able to distinguish a good coffee from a bad one.

Knowledge is the key to everything!

Understanding the meaning of this phase gives you the opportunity to independently select an excellent coffee. In addition to understanding how the final result in the cup should be.

It all depends on the roasting!

An intense, fragrant, aromatic, creamy coffee can only be obtained if the roasting is done in a workmanlike manner, combined with extraction done with awareness and knowledge.

Now let’s get to the heart!

Roasting – part 1

Definition: Roasting, from the Latin “torrefacere”, that is roast. Consisting torrere, meaning drying, and facere, meaning do.

NB. Roasting is a fundamental process, in which the bean changes both from a chemical and physical point of view:
  • Double its volume;
  • It loses 20% of its weight;
  • It changes color, going from green, to yellow, to cinnamon, up to the classic brown that we all know;
  • It develops its aromatic profile, without roasting the coffee would not have the taste that we love and seek so much;
  • It becomes brittle and therefore can be ground. The raw grain is dense and elastic, breaking and grinding it is therefore impossible.
Roasting is a process of transferring heat from the machine to the coffee bean.

Roasting – part 2

There are different ways of roasting coffee and different roasting profiles, depending on the extraction method with which we are going to prepare our coffee.

We had already talked a lot about this in another article that you can view by clicking on the button below.

To give a brief summary, I can tell you that in general if you want to extract a filter coffee it is good to use a light or medium-light roasted coffee, while if you want to extract an espresso, the ideal is a medium roast.

I’ll write another post on the reasons behind this, so keep reading!

At this point there is another decision to make: whether to roast in a blend or in single origin.

To be clear, 95% of the coffees we drink every day are blends, i.e. more coffees from different areas of the world, joined together in a single package.

You can then compose the blend with raw coffees and then toast them all together at once, certainly simpler and faster, but certainly not optimal as a method.

Or roasting each coffee separately, a slower and more complicated method but the final result pays off for all the efforts made!

We at Ernani have opted for single-origin roasting.

This is because each coffee is different from the other and to get the best out of each one will have to use different roasting curves, temperatures and times.

Let’s take a very simple example: let’s assume we have some leftover pasta between spaghetti, penne, farfalle and paccheri. If we throw all the shapes into boiling water at the same time and drain everything at the same time, we will have a well-cooked type, one that is probably overcooked and one that is still too raw.

The same goes for coffee!

The beans are not all the same, they belong to different varieties and species, with different sizes, densities, humidity and characteristics. Cooking them all together would mean finding a medium roasting curve that is more or less good for everyone, but not PERFECT for anyone.

This obviously requires a great deal of research on the part of the roaster, as he will first have to do many tests to understand how to roast that particular coffee to its fullest potential and then replicate it during the roasting phase, as for each coffee used.

And not only that: remember that there is no single roasting curve that never changes!

Every time the coffee batch changes or the seasons of the year pass, the roasting curve must be modified to be readjusted to the specific conditions of a given moment!

The skill of the roaster is precisely that of understanding what is the ideal roasting curve for that coffee at that particular moment and knowing how to always replicate it at maximum performance.

Roasting – part 3

Let’s see now how a roaster is made and how it works.

First of all you need to turn on the machine and its burner, bringing it up to temperature.

After that the raw coffee will be poured into the loading hopper, from where the beans are sucked and carried into the hopper above the machine. From here they will then enter the roasting chamber.

It is essential to have the ability to control everything that happens inside the chamber and then monitor the different phases, times and temperatures through a specific computer software, with probes that detect the temperatures inside the roaster.

The coffee inlet temperature is about 70/80% of the outlet temperature, that is: the coffee enters at a lower temperature than the outlet temperature.

The whole roasting process can be divided into 4 phases:
  1. Drying;
  2. Endothermic reactions;
  3. Exothermic reactions;
  4. Cooling down.

All in about 15/18 minutes depending on the type of coffee and the degree of roasting you want to obtain.

Roasting – part 4

Let’s now enter more specifically in the roasting phases!

In the first phase, that of drying, the bean loses the water contained within it.

The beans therefore start at about 12% humidity and contain a maximum of 1 / 1.5% of water.

In this phase the bean changes from green to yellow.

N.B. The new crops beans, having a higher degree of humidity than those of past years, will be roasted more evenly.

This is because, having a higher water content, and this being the medium through which the heat spreads inside the beans, the roasting will be identical between the outer surface and the central core of the beans.

Once the drying phase is over, the endothermic phase continues, i.e. the beans absorb heat from the roasting chamber.

The chemical-physical reactions of the beans are:

  • Transition from yellow to cinnamon;
  • Volume increase;
  • Weight loss.

Inside the beans, the pressures created by the water that has become steam are so strong that they cause it to crackle, just like popcorns do.

This is called the 1st crack and coincides with the end of the second stage.

Roasting – part 5​​

We now enter the 3rd phase of roasting: the exothermic phase, that is when the beans themselves release heat to the machine.

We are now in the aromatic development phase of the bean that will take us to the end of the roast.

In this phase we will choose which level of roasting to give to our coffees: light, medium or dark.

In the case of a light roast, we will let the beans come out exactly during the crack.

In the case of Caffé Ernani, having chosen a Medium Roast, the beans come out a few seconds after the 1st crack.

In the case of dark roasting, on the other hand, the beans will come out after a few minutes from the first crack, if not even at the 2nd or 3rd.

If you want to better understand the difference between the different roasting levels, just click on the button below.

The coffee is then poured into the cooling tank and the 4th phase begins.

Cooling is essential and must take place in a maximum of 5 minutes.

Let’s go back to the example of pasta that we all know very well: we are cooking the pasta, we taste it, we understand that it is ready, we turn off the stove but we leave the pasta still in the boiling water without draining it immediately.

What happen?

The pasta continues to cook.

The same goes for the beans!

Reaching temperatures exceeding 200 ° C, cooling it in the shortest possible time is essential!

Roasting – part 6

Now we just have to taste it, but first we have to wait a few more hours!

Freshly roasted coffee is full of gas, first of all CO2 (carbon dioxide), developed during cooking.

This moment is called degassing and lasts from 24 to 72 hours, always depending on the coffee and the desired result.

This will give the coffee the possibility to express a more complete and harmonious aroma, removing possible vegetal notes, a symptom of too much freshness after roasting.

And as we said at the beginning, tasting is important!

How does a roaster know if he has done his job well or badly if he does not know how to taste a coffee and does not recognize any negative or positive notes?

And if you want to find out more how to taste coffee, I leave you two other articles below!

Marketing, E-commerce e Social Media Manager
Coffee Lover


Martina Mazzoleni

Marketing, E-commerce e Social Media Manager Coffee Lover

Leave a comment

Your email address will not be published. Required fields are marked *

The reCAPTCHA verification period has expired. Please reload the page.

torna su
Apri chat
Bisogno di aiuto?
Ciao 👋
sono Martina, come ti possiamo aiutare?
Risponderò a qualsiasi tua domanda dal lunedì al venerdì, dalle 9.00 alle 18.00! ☕️💛