Typical characteristics of specialty coffee is noticeable acidity, distinctive body, and aroma. Coffee roasters are there to determine what roast profile is the best for each bag of coffee. The coffee have different characteristics depending on growing latitude, amount of sunshine, rain fall, temperature… anything you can think of contributes to the characteristics.
The following is example of interesting comparable objects.
The understanding in flavor of coffee based on origins and varieties is a key for coffee roasting. The major indicator to determine the appropriate roast profile is acidity and body. Those are what all the coffee potentially have, and roasters have to decide the balance of those two components. When the coffee is roasted lightly, it tends to have more acidity and lower body. When the coffee is roaster deeply, it tends to have more body and bitterness. Past couple of decades, deeper roasts have taken over lighter roasts due to the overwhelming growth of Starbucks. But apparently the specialty coffee shouldn’t always be roasted at Italian or French. Most of delicate origin flavors diminish at darker roast.
Now Starbucks started roasting relatively lightly and calling it blonds. The American specialty coffee roasters often prefers lighter roast, and so do Northern Europeans. That’s the clear trend of coffee today. The more experienced roasters started experimenting roasting profiles more sensitively. As the Bourbon from El Salvador isn’t the same as the Bourbon from Antigua, those roasters carefully adjust roastings as well.
On the other hand, understanding the relationship between characteristics of the coffee and depth of roast is a whole new different coffee world beyond Starbuck’s Latte.