Electrical current might be the key to a better cup of coffee
Christopher Hendon, a chemist at the University of Oregon, loves his coffee, so much so that studying all the factors that go into creating the perfect cup of tea is an important area of research for him. His latest project: discovering a new way to measure the flavor profile of coffee simply by sending an electric current through a beverage sample. The findings appear in a new paper published in the journal Nature Communications.
We have been following Hendon’s work for several years now. For example, in 2020, the Hendon lab helped design a mathematical model to make the perfect cup of espresso, again and again, while minimizing waste. The flavors of espresso come from around 2,000 different compounds extracted from the coffee grounds during brewing. This can make it difficult 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 measured property known as extraction yield (EY): the fraction of coffee that dissolves in the final beverage. This in turn depends on controlling the flow rate and pressure of the water as the liquid seeps into the coffee grounds. The model is based on how lithium ions propagate through the electrodes of a battery, similar to how caffeine molecules dissolve in coffee grounds.
Three years later, Hendon’s team turned its attention to studying why microscopic clumps form in the first place, particularly at very fine grind levels. The culprit is static electricity resulting from fracturing and friction between grains during grinding. Hendon thought that reducing this static would be a good way to eliminate these clumps. The technical term is triboelectricity, which results from the accumulation of opposite electrical charges on the surfaces of two different materials due to contact with each other.
Similar charge accumulation also occurs during volcanic eruptions. So Hendon collaborated with volcanologists Josef Dufek and Joshua Méndez Harper, who were regulars at the same local coffee shop and had noted striking similarities between coffee science and plumes of volcanic ash, magma, and water.
Their experiments confirmed that adding a single jet of water to coffee beans before grinding them can significantly reduce the static electrical charge of the resulting grounds. This, in turn, reduces clumping during brewing, producing less waste and a strong, consistent flow needed to produce a flavorful cup of espresso. Good baristas already use the water trick; This is called the Ross droplet technique. But this was the first time scientists rigorously tested this well-known hack and measured the actual charge of different types of coffee.
