The coffee blend is a relatively modern invention of coffee roasters who have used it to characterize their production and thus their company. It is not easy for a roaster to provide a blend that is qualitatively consistent over time because it is often difficult to procure high quality raw material in large quantities, and then because "good" coffee requires constant research, continuous testing with trials and tastings, and a lot of fussiness.
Moreover, it is not enough to procure good coffees and mix them together to have a good blend: there are some coffees that do not get along with each other, that do not bind, while there are others that add up certain characteristics turning them into defects. For example, acidity, which to a small extent is a characteristic of finesse, if it becomes excessive due to the presence of two acidic coffees, it disturbs.
Ultimately, the coffee blend should be balanced, with the right amount of sweetness, aroma, acidity, full taste, aroma and lingering aftertaste.
English
Italian 
German 
Spanish