Picture this: two volcanologists and a chemist walk into a coffee shop, not for a joke, but to make a scientific discovery that could revolutionize your morning espresso.
Researchers from the University of Oregon have found a simple trick – adding a little water to coffee beans before grinding – that makes a more consistent and better espresso while also reducing waste.
This might sound surprising, but the key to a better brew is understanding static electricity.
When you grind coffee beans, they can develop a static charge. This charge causes the grounds to clump together, making the water flow unevenly through them when brewing.
This can result in your espresso being different each time you make it, and it also means some of the coffee gets wasted, stuck together and not fully used.
Christopher Hendon, a chemist at the University of Oregon and affectionately known as Dr. Coffee, explains that for espresso, which is all about precision, having a consistent flow of water through the coffee grounds is really important.
By making the flow more consistent, you not only get a better-tasting espresso each time, but you also use less coffee.
This is great news for coffee shops that make hundreds of espressos a day – even a small saving on each cup adds up to a lot over a year.
The idea for this research came about in a coffee hour hosted by Hendon’s coffee lab, a regular event for the campus community.
Here, volcanologists Josef Dufek and Josh Méndez Harper saw parallels between the coffee and their usual research subjects – volcanic ash and magma. Both involve particles interacting in different states, but thankfully, coffee is much less hazardous to study.
Hendon’s team had previously found that coffee grounds, especially when ground very finely, tend to form tiny clumps.
These clumps, though invisible to the naked eye, affect the quality of the coffee by reducing the amount of flavor extracted from each ground. The new study aimed to understand why these clumps form and how to prevent them.
The researchers suspected static electricity played a role in clump formation. To test this, they used a method similar to one used for measuring electric charges on volcanic ash, involving a device called a Faraday cup.
By grinding coffee above this instrument and capturing the falling particles, they could measure the electric charge on them.
Their experiments showed that the internal moisture of the coffee beans had a big impact. Dark roast coffees, which are roasted longer and have less moisture, clumped more and had a negative charge. Lighter roasts, with more moisture, had a positive charge.
Adding a bit of water before grinding removed the static charge and reduced clumping, leading to a 10% increase in yield from the coffee.
For baristas, this means a more efficient and consistent brewing process. Hendon points out that some in the industry might already know this trick, but the study provides scientific validation.
Interestingly, the research also offers insights for the volcanologists. Like coffee grounds, volcanic ash particles can become highly charged, affecting phenomena like volcanic lightning and the spread of ash after eruptions. Studying coffee grounds allows them to explore the physics of particle fragmentation in a more controlled environment.
This project, supported in part by the Department of Energy, the National Science Foundation, and NASA, highlights the unexpected connections between different fields of science.
It shows how a casual coffee hour chat can lead to insights benefiting both your morning espresso and the study of explosive volcanoes.
