A team of chemists and volcanologists at the University of Oregon have discovered that adding a spritz of water to coffee beans before grinding can reduce static electricity and create a more consistent, stronger-tasting espresso shot. The study, published in the journal Matter, shows how moisture in coffee beans affects the build-up of charge and how it can be manipulated. The researchers found that friction and fractures result in tiny particles that accumulate electric charge in the process of grinding coffee. The study also sheds light on the burgeoning field of coffee science, which draws together experts from various disciplines to conduct drinkable experiments and probe the fundamental science behind a cup of joe. The researchers suggest that adding a small amount of water to whole-bean coffee beans before grinding can make the coffee more accessible during brewing, resulting in more coffee being brewed.
A collaboration between scientists at the University of Oregon and a volcanology lab led to the discovery that moisture modulates the amount of charge on coffee grounds. The team used a custom-built Faraday cup to measure the charge on individual particles and calculate the density of that charge. They found that lighter roast coffees with more internal moisture gained less static charge during grinding and tended to charge positively, while darker roasts gained more charge and tended to accumulate negative charge. The scientists were intrigued by the fact that coffee sometimes charged in one direction and sometimes in the other, and that internal moisture played a key role. They discovered that suppressing charging altogether by adding external moisture, just a squirt of water before grinding, reduced static and avoided clumps in the coffee. This study is a prime example of how many low-hanging scientific fruits remain in the world of coffee, with opportunities to bring rigorous experimental techniques and measurements to something many people do one or more times a day.
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