Researchers have developed a fast, practical test to evaluate quality of black coffee, offering baristas and scientists a clearer window into flavor without complex lab work.
Bumbaugh et al. show that cyclic voltammetry can be used without any additional sample preparation to directly measure the strength of a coffee beverage and, separately, how dark the coffee has been roasted. Image credit: Sci.News.
Existing methods to evaluate coffee typically rely on tasting panels or indirect measurements, such as estimating the amount of dissolved material in a sample.
However, these methods cannot distinguish chemical differences caused by roast level or brewing choices.
Other laboratory techniques can identify individual molecules, but these are slow, expensive, and often impractical for routine use.
“Since the 1950s, the coffee industry has sought quantitative methods to assess beverage qualities beyond those informed by sensory panels,” said University of Oregon researcher Christopher Hendon and his colleagues.
“In the meantime, a litany of research on the topic has revealed that beverage concentration and roasted bean color are the two primary and independent factors that dictate the sensory perception of coffee.”
“Bean color is readily determined by spectrophotometry, while the most widely used technique to measure concentration of solvated coffee relates the refractive index of the beverage to an effective concentration through an empirically derived polynomial.”
The researchers propose a new method for rapidly assessing the strength of black coffee using an electrochemical test known as cyclic voltammetry.
The test involves applying a voltage to and measuring the current passed as the coffee responds to the electric field, allowing for differences in strength and roast to be isolated.
In their study, the scientists observed a linear relationship between beverage strength and total electrical charge, with these signals also becoming weaker as the roast of the samples became darker.
This weakening is attributed to the roast‑dependent molecules, including caffeine, sticking to the platinum electrode during the measurement.
The methods were validated through comparison with color and flavor descriptions from a UK-based roastery’s quality‑control process.
“This test could help to distinguish between batches of brewed coffee that look identical and have similar dissolved‑solid readings but differ in flavor,” the authors said.
“The results suggest that this test could serve as a sensitive and reliable way to assess coffee composition, complementing existing tools used by the industry.”
The team’s work was published in the journal Nature Communications.
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R.E. Bumbaugh et al. 2026. Direct electrochemical appraisal of black coffee quality using cyclic voltammetry. Nat Commun 17, 3618; doi: 10.1038/s41467-026-71526-5
