Universal color curve for roasted arabica coffee

Nature scientific report July 2025

From UC Davies

Conclusion

To the best of our knowledge, this study is the first to systematically investigate the dynamics of coffee color during roasting using industry-standard roast profiles and various coffee origins on a commercial scale.

Overall, our results demonstrate that changes in coffee color during roasting follow a consistent path in the CIELAB color space, which we define as “the universal roasted arabica coffee color curve.”

standardize roast-level definitions:

 Furthermore, regardless of the roast profile or origin, our coffees consistently exhibited approximately the same L*a*b* values at significant roast milestones such as color change, first crack, and second crack.

Applications:

 The universal roasted arabica coffee color curve provides a valuable quantitative QC standard for defining roast levels in the coffee industry.

 Future work should explore a broader range of coffee species, origins, and postharvest processing methods—including decaffeinated coffee—as well as other roast profiles, including shorter roast times.

Additionally, future studies should establish correlations between the CIELAB color space and roast level measurement scales, including Agtron, Colorette, and Colortrack, to ensure the curve’s applicability across different color-measuring instruments. Further research should also explore the correlation between chemical composition and color development during coffee roasting.