Chemistry · Level 3 · Advanced
Caffeine content in filter coffee brews as a function of degree of roast and extraction yield
Lindsey ZR, Williams JR, Burgess JS, et al. (2024). Scientific Reports. doi:10.1038/s41598-024-80385-3 · CC BY 4.0
Step 1 of 2Read the paper
Do dark roasts have less caffeine than light roasts? Earlier studies disagree. Here two Ethiopian coffees were roasted to five degrees of roast and brewed for 1, 2 or 10 minutes under tightly controlled conditions (90 brews). Caffeine was measured by HPLC, extraction yield by refractometry and bean porosity from electron microscope images.
How to read it
- The Introduction explains why past results conflict; note every variable the authors try to hold constant.
- Learn Equation 1 (extraction yield) before reading Figures 4 and 6.
- Figure 6 is the key: compare caffeine at the same extraction yield versus under the same brewing conditions.
- Read the Conclusions for the two competing mechanisms and the limits the authors admit.
Step 2 of 2Take the test
15 questions · about 50 minutes including reading · pick an answer to see straight away if it’s right. Nothing is saved.
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Paper: Lindsey ZR, Williams JR, Burgess JS, et al., Scientific Reports (2024), licensed CC BY 4.0. Summary and questions are Research Nest’s own; read the original for the full study.