We have already introduced the roasting process in our previous article and explained the concepts of light, medium and dark roasts.
This time, we are going to focus on different stages of the roasting that can be divided into 5: the drying, the yellowing, the first crack, the roast development (where the roast degree and the colouring of the beans is decided) and finally the second crack.
- Drying: Raw coffee initially contain 7% to 11% of water that is spread evenly through the structure of the bean, that would not let it turn brown.
The first step of the roasting of the bean is for them to take some time and heat at a temperature high enough for the water to start evaporating. During this stage, the beans barely change look or smell.
- Yellowing: This stage begins once the water has been driven out of the beans, it is the first browning reaction where the coffee beans go from still having a very strong raw aroma to expanding and having their skin and chaff flaking off. Those are then separated from the beans thanks to the air that flows through the roaster and collected in order to avoid any accident (especially risk of fire).
- The first crack: As mentioned before, this is the point where the coffee beans start acquiring the various tastes and aromas that are developed and chosen by the roasters. This stage is recognisable by the popping noise that is made when the bean breaks open due to the amount of cases and water vapour inside.
From this stage, the temperature of the beans themselves will not rise as much as before and the roaster will then have to be very careful about it and make sure not to “bake” the beans. Also, this is the point where every roaster will decide of the flavour and can stop the process at anytime.
- The second crack: This point is when the second crack will appear and all the oils contained by the beans start to be driven out of their surface. The flavour after this point does not really depend on the kind of coffee that is used as it results more into a charring or burning of the beans, which can also make the process more dangerous (the beans are at risk of catching fire). This is where dark roasts such as “Italian” or “French” roasts are made, that typically present a high body and bitterness.