Measuring Roast Level with the Agtron Scale
You probably noticed that we do not include a roast level on our bags. Although we consider most of our coffees to be in the light to medium range, using this terminology carries with it some subjectivity.
There are many aspects of coffee that will contribute to the character of the beverage in your cup (to name a few):
- coffee plant variety;
- processing method at origin;
- coffee varietal;
- how it's roasted (and the level of development of that roast); and
- how it's brewed.
These attributes and how we manipulate the variables during the roasting process impact the coffee's body, level and character of its acidity (brightness), sweetness, aftertaste and the flavor notes.
On the roasting side, we can communicate the roast level by a reading on the Agtron color scale. Although roast level is just one of the aspects that will contribute to flavor, the number can tell us a little more about the sensory experience we can find in the cup.
What do the numbers mean?
The number readings we get from the Agtron represents the degree of roast. In our QC lab, we take both the interior and exterior bean color reading, and what you see is the interior bean color. The "roast level" indicators on the scale we are using are our internal references we have paired with a roast level and where we consider those roast levels to fall on the Agtron scale:
The lower the number, the darker roast. The higher the number the lighter the roast. But keep in mind these are our internal references only and they don't necessarily pertain to any broader industry benchmarks (remember the earlier word 'subjective':).
So, how does it work?
In a very short nutshell (lots more to come!), we use a light reflectometer that bounces ultraviolet light of a small sample of coffee and then analyzes its color. We take measurements of both the whole bean, as well as ground coffee (more on these differences soon, as well!).
We will begin to add a roast level (Agtron number) to every coffee page over the near future so keep an eye out.