A Spritz of Water May Improve Your Coffee

Research shows that wetting the beans slightly before grinding really does help


Discovering the Benefits of Water Spritzing

A unique collaboration in science has resulted in a handy tip for coffee enthusiasts—spritz your beans with water. Christopher Hendon, co-author of a new study in the journal Matter, is a chemist who runs a coffee laboratory out of the University of Oregon. He worked with volcanologist Josh Mendez Harper to use a modified tool that's commonly used to study charges in volcanic ash to better understand how the static generated during grinding affects coffee grounds. Their study found that spritzing roasted coffee grounds with a small amount of water will create less static electricity once the grinder begins whirring, the Washington Post reports. This makes the grounds less messy, but more importantly, stops them from clumping, increasing concentration by about 10%. This resulted in stronger espresso shots that had more consistent flavor.

Validating Baristas' Techniques

These findings are not news to many baristas, who have long known the challenges of coffee grounds flying all over the place. The process they use to dampen beans before grinding even has a name: the Ross Droplet Technique, per Ars Technica. But the research certainly justifies the technique, as well as gives some scientific understanding to why it works. "What's cool about this paper is it's putting some hard science, some hard data, behind understanding the mechanism," says William Ristenpart of UC Davis' Coffee Center, who was not involved in the research. Per Daily Coffee News, the study tested many types of beans and took into account various factors, including country of origin and whether they were commercially produced or roasted in-house. Water content, roast color, and ground size had the most influence on static charges.

Expert Recommendations for Moisturizing Beans

Hendon has been busy publishing papers with findings coffee lovers can apply at home—his other work concludes we should chill beans just prior to grinding, and also use coarser grounds. Hendon shared how people at home can start moisturizing beans, advising to start conservatively, with about 0.1 milliliters of water per 20 grams of beans. "Generally, start at the low end and work up until you start to see the flow rate benefits," he said. Meanwhile, his collaborator wishes to continue connecting the parallels in their fields. "If you brew a pour-over coffee, the physics there, the math, is the same you apply to water percolating through soil or magma moving through a porous rock matrix," says Mendez Harper. (Coffee pods might be more environmentally friendly than you think.)