You’re a coffee afficionado, so you must have heard of the Ross droplet technique, right?
Just water to grind
From adding butter to your coffee to grinding beans that have already been through another creature’s digestive system, every few months it seems there’s a new fad that coffee fans must try.
But now, with the help of volcano scientists, researchers have discovered perhaps the simplest way of all to improve the flavour and consistency of your favourite roast. Just add a drop of water before you grind.
More even and more intense
Published in the journal Matter, the study was supported by the U.S. Department of Energy, the National Science Foundation, the Camille and Henry Dreyfus Foundation, and the Coffee Science Foundation with support from Nuova Simonelli.
Our paper on triboelectrification during coffee grinding in @Matter_CP. Key messages: a couple drops of water on whole beans *before* grinding turns off chargeing, preventing clumps from forming, which makes higher concentration extracts. + less mess! https://t.co/HCxtgiY4hY pic.twitter.com/ltb2FuoztK— Christopher H. Hendon (@chhendon) December 6, 2023
It explains that grinding coffee is similar on a small scale to the process that occurs on a gigantic scale when a volcano erupts: magma particles rub together creating lightening. In the same way, friction during the coffee grinding process causes static electricity, which in turn causes coffee grinds to stick to the grinder, clump together and be “zapped” occasionally. This creates an uneven grind and unpredictable flavour results.
Adding a tiny drop of water, labelled the “Ross droplet technique”, reduces mess, helps the coffee grind more evenly and, said researchers, improves intensity– results that could yield 10%–15% in flavour concentration in the coffee industry, which is worth hundreds of billions worldwide.
Dark roasts yield finer, negatively charged particles
The researchers compared coffee beans from different countries of origin, that had undergone various processing methods (natural, washed, or decaffeinated). The degree of roast and moisture content, as well as how coarse the grind is, were other factors investigated.
Of these, the roast, moisture level and coarseness of grind were found to make a difference. Coffee with a higher internal moisture content, ground at a coarser setting, caused less electricity to be produced. Light roasts produced less charge, and this charge was “more likely to be positive.” Darker roasts which are usually drier too, became negatively charged and saw more charge created overall. The study also demonstrated that dark roast coffees yield finer particles than light roasts even when ground at the same setting.
Coffee and geophysics
“It’s sort of like the start of a joke—a volcanologist and a coffee expert walk into a bar and then come out with a paper,” commented first author and Portland State University volcanologist Joshua Méndez Harper, “but I think there are a lot more opportunities for this sort of collaboration, and there’s a lot more to know about how coffee breaks, how it flows as particles, and how it interacts with water. These investigations may help resolve parallel issues in geophysics—whether it’s landslides, volcanic eruptions, or how water percolates through soil.”