Coffee grinding produces large quantities of static charge due to both fracturing and rubbing. Charge causes particle aggregation and discharge, a familiar problem in industrial coffee production. New research demonstrates that the magnitude of charge depends on the roast profile and, more importantly, the internal moisture content of whole-bean coffee.
“Moisture, whether it’s residual moisture inside the roasted coffee or external moisture added during grinding, is what dictates the amount of charge that is formed during grinding,” said Dr. Christopher Hendon, a computational materials chemist at the University of Oregon.
“Water not only reduces static electricity and therefore reduces mess as you’re grinding, but it can also make a major impact on the intensity of the beverage and, potentially, the ability to access higher concentrations of favorable flavors.”
“These improvements to coffee extraction could have massive economic implications for the coffee industry, which is worth $343.2 billion or 1.5% of the US gross domestic product.”
“Pushing the concentration up by 10-15% for the same dry coffee mass has huge implications for saving money and improving quality.”
That coffee grinding produces static electricity has long been known within the coffee industry, where this electrification causes clumping and occasional zaps, but little was known about how different coffee attributes contribute to this phenomenon or how it impacts brewing.
To identify factors associated with static electricity generation during coffee grinding, Dr. Hendon teamed up with volcanologists who study similar electrification processes during volcanic eruptions.
“During eruption, magma breaks up into lots of little particles that then come out of the volcano in this big plume, and during that whole process, those particles are rubbing against each other and charging up to the point of producing lightning,” said Dr. Joshua Méndez Harper, a volcanologist at…
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