Coffee Data Science
Ultrasonics on Coffee Beans Post-Roast
A small, slightly crazy experiment.
Ultrasonics have proven to be interesting for brewed coffee, and I was curious if ultrasonic waves could be used to force coffee beans to degas faster or otherwise affect the flavor of coffee beans. So I ran a test, and I didn’t find a definitive answer at the end.
I placed roasted coffee beans in bag, and then I held them under the water in an ultrasonic bath for 5 minutes. I did this for two roasts to see what the results would be. The coffee roasts for the baseline and comparison were a split between one roast, so all the metrics on the beans are the same.
Metrics of Performance
I used two sets of metrics for evaluating the differences between techniques: Final Score and Coffee Extraction.
Final score is the average of a scorecard of 7 metrics (Sharp, Rich, Syrup, Sweet, Sour, Bitter, and Aftertaste). These scores were subjective, of course, but they were calibrated to my tastes and helped me improve my shots. There is some variation in the scores. My aim was to be consistent for each metric, but some times the granularity was difficult.
Total Dissolved Solids (TDS) is measured using a refractometer, and this number combined with the output weight of the shot and the input weight of the coffee is used to determine the percentage of coffee extracted into the cup, called Extraction Yield (EY).
Shots
The paired shots showed the ultrasonic process might be helping taste. There was a bad failure point on the second shot for the Papua roast for both the baseline and ultrasonic that didn’t have to do with the process.
In terms of beans vs beans and paired shots, the taste scores seem both good and bad.
The same is true for EY: no clear performance improvement is seen.
This experiment was a case of pure curiosity. One of the complicating factors is that I had some shower screen issues for the first two Papua shot pairs. I might try this again but maybe with the roasted beans in the water instead of in a bag.
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Further readings of mine:
My Second Book: Advanced Espresso
My First Book: Engineering Better Espresso
