Electrical current might be the key to a better cup of coffee - Ars Technica

Overview

Electrical current might be the key to a better cup of coffee

University of Oregon scientists repurposed battery-testing tool to better measure coffee’s flavor profile

Details

University of Oregon chemist Christopher Hendon loves his coffee—so much so that studying all the factors that go into creating the perfect cuppa constitutes a significant area of research for him. His latest project: discovering a novel means of measuring the flavor profile of coffee simply by sending an electrical current through a sample beverage. The results appear in a new paper published in the journal Nature Communications.

We’ve been following Hendon’s work for several years now. For instance, in 2020, Hendon’s lab helped devise a mathematical model for brewing the perfect cup of espresso, over and over, while minimizing waste. The flavors in espresso derive from roughly 2,000 different compounds that are extracted from the coffee grounds during brewing. So it can be challenging for baristas to reproduce the same perfect cup over and over again.

That’s why Hendon and his colleagues built their model for a more easily measurable property known as the extraction yield (EY): the fraction of coffee that dissolves into the final beverage. That, in turn, depends on controlling water flow and pressure as the liquid percolates through the coffee grounds. The model is based on how lithium ions propagate through a battery’s electrodes, similar to how caffeine molecules dissolve from coffee grounds.

Three years later, Hendon’s team turned their attention to studying why the microscopic clumps form in the first place, particularly at very fine grind levels. The culprit is static electricity arising from the fracturing and friction between the beans during grinding. Hendon thought reducing that static would be a good way to eliminate those clumps. The technical term is triboelectricity, which arises from the accumulation of opposite electric charges on the surfaces of two different materials due to contact with each other.

A similar charge build-up also occurs during volcanic eruptions. So Hendon collaborated with volcanologists Josef Dufek and Joshua Méndez Harper, who were regulars at the same local coffee house and had noted striking similarities between the science of coffee and plumes of volcanic ash, magma, and water.

Their experiments confirmed that adding a single squirt of water to coffee beans before grinding can significantly reduce the static electric charge on the resulting grounds. This, in turn, reduces clumping during brewing, yielding less waste and the strong, consistent flow needed to produce a tasty cup of espresso. Good baristas already employ the water trick; it’s known as the Ross droplet technique. But this was the first time scientists had rigorously tested that well-known hack and measured the actual charge on different types of coffee.

There are existing methods for collecting information on coffee’s chemical composition, most notably liquid or gas chromatography combined with mass spectrometry. But these kinds of analyses are expensive and time-consuming, and predictive results are limited. There are also electrochemical techniques for measuring the concentration of caffeine and other molecules, but these have not taken into account coffee strength—a property determined by all the variables that go into preparing a cup of coffee, such as coffee and water masses, grind settings, water temperature and pressure, roast color, and so forth. That’s the information likely to be most helpful to baristas.

The coffee industry typically uses a method for measuring the refractive index of coffee—i.e., how light bends as it travels through the liquid—to determine strength, but it doesn’t capture the contribution of roast color to the overall flavor profile. So for this latest study, Hendon decided to focus on roast color and beverage strength, the two variables most likely to affect the sensory profile of the final cuppa.

His solution turned out to be quite simple. Hendon repurposed an electrochemical tool called a potentiostat, typically used to test battery and fuel cell performance. Hendon used the tool to measure how electricity interacted with the liquid. He found that this provided a better measurement of the flavor profile. He even tested it on four different samples of coffee beans and successfully identified the distinctive signature of a batch that had failed the roaster’s quality-control process.

Granted, one’s taste in coffee is fairly subjective, so Hendon’s goal was not to achieve a “perfect” cup but to give baristas a simple tool to consistently reproduce flavor profiles more tailored to a given customer’s taste. “It’s an objective way to make a statement about what people like in a cup of coffee,” said Hendon. “The reason you have an enjoyable cup of coffee is almost certainly that you have selected a coffee of a particular roast color and extracted it to a desired strength. Until now, we haven’t been able to separate those variables. Now we can diagnose what gives rise to that delicious cup.”

DOI: Nature Communications, 2026. 10.1038/s 41467-026-71526-5  (About DOIs).

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Key Takeaways

• Electrical current might be the key to a better cup of coffee

• University of Oregon scientists repurposed battery-testing tool to better measure coffee’s flavor profile

• University of Oregon chemist Christopher Hendon loves his coffee—so much so that studying all the factors that go into creating the perfect cuppa constitutes a significant area of research for him

• We’ve been following Hendon’s work for several years now

• That’s why Hendon and his colleagues built their model for a more easily measurable property known as the extraction yield (EY): the fraction of coffee that dissolves into the final beverage