The Final Roasting Temperatures
These values are of the utmost importance for the final sensorial result.
The ratios between acidity and bitterness are directly related to the final temperature: a very light coloured coffee, like our ICC Roast degree, which comes out at about 218° C, is only very slightly bitter, with a strong acid note.
A very dark coffee, on the other hand, like our ICXS (approx. 224°C) presents a quite pronounced bitterness, while the acidity is almost absent. Between these two, we also have ICN (approx. 220°C) and ICS (approx. 222°C), the first called Espresso and the second Ristretto.
It should be considered that acidity strongly emphasises the perception of aromas so, as this characteristic is gradually mitigated by darker roasting, the perception of the aromas should fade. Add to this the fact that as the temperature of the coffee rises gradually so does the production of CO2 inside its cells, causing the release of more gas from the cells, accompanied by more aromas.
But there is a “controlling” factor of these phenomena which consists in the actual formation of the aromas. At lower temperatures, indeed, certain aromas cannot be formed and will, therefore, be absent from coffees roasted in this way.
The result is that the lighter-coloured coffees present a “fresher” sensorial spectrum, because they contain what are known as “low-boiling” aromas, the aromas that are in a gaseous state at lower temperatures, such as the aromas of almost all types of flowers and many types of fruit. “Heavier”, “high-boiling” aromas, such as honey, caramel, banana, croissant, patisserie, fresh bread, coal (a magnificent aroma in its pure state) and goudron, are less present.
A darker coffee, on the other hand, will lose part of its “low-boiling” aromas (due to the higher amount of gas released as explained above), but will have formed more “high-boiling” aromas, maintaining an equally powerful and complex aromatic spectrum (volume of aroma).
The degree of roasting depends on consumer tastes: the aromatic spectrums and taste compositions (acid/bitter) are very different, but always very complex and exceptionally pleasant.