Direct electrochemical appraisal of black coffee quality using cyclic voltammetry

Despite coffee's popularity, there are no quantitative methods to measure a chemical property of a black coffee drink in situ and relate it to a flavor experience. Here we 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; these two properties are implicated in the sensory profile of the beverage. We show that the current passed for the cathodic features that precede hydrogen evolution are linearly related to beverage strength. The same features are suppressed with subsequent cycling due to coffee material accumulating on the electrode. The magnitude of suppression is directly related to roast color, which dictates the ensemble chemical composition and flavor of the beverage. Together, this voltammetric analysis decouples beverage strength from roast color and offers a strategy for rapidly assessing flavor-correlated chemical properties of coffee.