Coffee enthusiasts who swear by adding water to coffee beans before grinding may have science on their side, according to a recent study conducted by researchers at the University of Oregon. The findings shed light on the impact of the "Ross droplet" technique, a practice that began as a solution to the messiness of the coffee-making process but has evolved into a method believed to enhance the brewing experience.

The primary motivation for adding water before grinding stems from the chaotic nature of the grinding process, where static electricity generated by friction causes coffee particles to scatter in all directions. Christopher Hendon, study coauthor and associate professor of computational materials chemistry at the University of Oregon, explained, "Dust comes out of the grinder, it’s like a plume that covers everything. But if you add a little water, it seems to not go everywhere. It’s cleaner. That was the primary reason people did it."

The study, published in the journal Matter on December 6, delves into the more subtle and intricate aspects of this technique. Researchers discovered that water acts as an insulator, mitigating the static charge responsible for the messy dispersion of ground coffee. This process, known as the "Ross droplet" technique, was initially borrowed from the materials production industry, specifically wood pulping.

Hendon highlighted that what began as a remedy for messiness eventually led to a more sophisticated understanding of its impact on flavor. The theory suggested that by reducing static electricity, water prevents the formation of microscopic clumps during brewing, which can hinder the extraction yield—the amount of coffee that dissolves in the liquid.

To put the "Ross droplet" technique to the test, the research team, including two volcanologists, repurposed a tool used to measure electric charges on wildfire and volcanic ash. The addition of small amounts of water, ranging from one droplet upwards, was found to "passivate" the static charge, allowing coffee to exit the grinder without being charged.

The study determined that, on average, adding water increased the extraction yield by 10%. While this may not necessarily translate to a significant difference in flavor, it confirms the benefits of the technique. Hendon advised home users to start with a single drop of water and experiment with quantities, emphasizing the nuanced nature of the process.

However, there is a catch. The benefits of adding water are most pronounced in espresso and, to a lesser extent, filter coffee. For brewing methods like cafetiere, French press, or AeroPress, where coarser grinds are used, the technique doesn't yield the same improvements, as Hendon explained, "all of the water is already touching all of the coffee."

Lance Hedrick, a coffee expert and professional barista, commended the study for attempting to demystify the process but suggested more tests with different grinder models for conclusive evidence. François Knopes, a professional coffee roaster and taster, recommended spraying beans before grinding for tasting evaluation but questioned the practicality of the technique in professional settings.

While the "Ross droplet" technique may currently be deemed impractical for most professional setups, Hendon envisions the development of technologies that harness the power of adding water on demand. As coffee enthusiasts eagerly explore ways to perfect their brew, the study adds a scientific dimension to the age-old practice of enhancing the coffee-making process.