Lecture Description

Coffee professionals have long known that the “roast profile,” i.e., the temperature versus time inside the roaster, strongly affects the flavor and quality of the coffee. Here we investigate roast profiles of the same total duration but very different dynamics inside a 5-kg commercial drum roaster, including profiles like "fast start," "slow start", "negative rate-of-rise," or "exaggerated flick."  In this presentation we report on two exciting sets of observations. First, we show that the "titratable acidity," which is highly coordinated with perceived sourness, invariably peaks during first crack and then decays to its original value by second crack. Although the dynamics of the TA development varied with roast profile, the peak TA surprisingly exhibited almost no statistically significantdifferences among roast profiles. Second, we report on how the different roast profiles impact the color of the roasted beans.  Despite dramatic differences in roast profile, our data indicate that the beans always follow a "universal coffee color curve" when plotted in the CIELAB L* a* b* color space.  Our results provide insight on how to manipulate and achieve desired sourness during roasting, and also point the way towards color standards for the coffee industry.

Date: Sunday, April 14, 2024
Time: 9:00am - 10:00am
Room Number: N426AB

Speakers

Laudia Anokye-Bempah (she/her)
Student Researcher, University of California, Davis

Laudia Anokye-Bempah is a Ph.D. student in the Biological Systems Engineering Program at the University of California Davis. Her research focuses on the kinetics of coffee roasting, with the ultimate goal of designing a “Coffee Roasting Control Chart” that will be used to produce the desired attributes in roasted coffee. Prior to her doctoral studies, Laudia received her MSc. in Biological Systems Engineering also from the University of California Davis, where she researched the use of desiccants for proper moisture preservation in green coffee during storage and transportation, and a BSc. in Food Process Engineering from the University of Ghana where she is from.