Coffee is just like two dimensional art expressed by coffee roasters. While origin based characteristics are on the x-axis, roasting based characteristics are on the y-axis. A cup of coffee is a collaborative results of coffee bean and roasting. Neither good coffee bean nor precise roasting skills wouldn’t make a perfect cup of coffee. The roasters are required to deeply understand both coffee varietals and roasting.
Coffea Arabica is suited for a high elevation which has extremes of temperature in one day. This terroir contributes to the depth of flavor. The various degree of acidity and depth of body are generated. For instance, in Central America, such countries as Guatemala, Costa Rica, and Panama, which averagely have higher coffee growing elevation, are known as high quality coffee producers rather than Honduras or El Salvador, which have coffee farms a lower elevation (This was a bit rough comparison, and of course other factors matter too).
Guatemala’s Antigua and Costa Rica’s Tarrazú have clear difference in characters. Their difference is mostly due to varietals rather than terroir. Bourbon varietal from Antigua has brighter acidity and clearer body than Caturra varietal from Tarrazú. I would imagine Tarrazú could produce high quality Bourbon if they decided to sacrifice Caturra’s high productivity.
Roasting is about how well it could express the coffee beans natural characteristics. Based on each bean’s origin/varietal characteristics, the roast profile is determines.
Some Bourbon from Antigua Guatemala has solid flavor that can stand for widely medium to dark roasts, on the other hand, the same Bourbon varietal from El Salvador tends to loose its flavor edge in deep roasts.
Geisha from Esmeralda estate of Panama has juice like sweet fruited acidity, but its body is very modest. The Typica varietal from Kona Hawaii has elegant acidity and moderate body. Because of their light body high acidity character, deeper roasts aren’t recommended.
The recent trend of specialty coffee seems to like to enhance acidity by light roasts. This trend is considered to be started from SCAA and COE’s cupping method. The purpose of their cupping is to evaluate the potential of coffee beans, and solely for that purpose, light to medium roasts are used. Not necessarily the lighter roasts are better than others. It almost seems lighter roasts are recognized as better for coffee than darker roasts among general consumers. It certainly is a trend, but it’s not more than just a trend.
What coffee roasters can offer is to carefully choose coffee bean and the right roast profile which maximizes the beans’ potential.