The roasting process, besides making green coffee edible, it also generates the characteristic aromatic and sensory profile of each coffee blend.
The blending (various types of green coffee) and roasting are a real art that has been acquired over years of experience and it is not surprising that roasters keep their formulas extremely secret, passing them on from generation to generation.
One should not forget that coffee is an agricultural produce and its aromatic-sensory characteristics vary according to environmental conditions.
The roaster’s main problem is that of creating blends that maintain the taste and the constant aroma of the blend despite the changes in production from year to year.
This duty is given to internal or external “specialised tasters” and independent professionals. It is up to them to decide the percentage of which kind of coffee bean and production the blend is composed by.