Have you ever sat at a brew bar, watching a barista wave a kettle around as if they are conducting an invisible orchestra, or as if it’s attached to the ceiling with a bungee? “The yo-yo pour” is our name for this kind of unintended up-and-down motion that a barista sometimes makes when brewing a pour-over coffee.
This movement is a natural consequence of the arm being hinged at the elbow, and it consequently takes a bit of practice and concentration to learn to pour from a steady height. Experience tells us that the height you pour from matters, and last year we published an intriguing white paper by astrophysicist barista Jonathan Gagne that explains the possible reason for this.
Since the pour height affects extraction, the logical conclusion is that pouring from a steady height will result in a more even extraction than moving the kettle up and down. We set up some experiments intended to confirm this, and aimed to show that the yo-yo motion harms the coffee. The results, however, were far from what we expected.
Subscribers can read the full details of these experiments in our white paper published last week. What we found is that the yo-yo motion, or lack of it, is relatively unimportant. Rather, it seems to be the overall pour height that matters, and controlling this can make the difference between a clogged, thin, astringent brew and a rich, vibrant, fruity one.
BH Coach Jessica Sartiani explains the experiments we carried out to test the yo-yo pour.
When we compared the yo-yo method to pouring from a steady height, we were surprised to find the yo-yo pour actually seemed to perform better. Both brewing methods resulted in the same average TDS, but the yo-yo brews drew down much more quickly than the brews from the steady height, and, to our surprise, tasted better. Pouring from a steady height resulted in a slower draw down, and astringency in the brews — suggesting that the filter paper was getting clogged and causing channelling.
Clogging like this is often caused by excessive agitation in the brew. Gagne’s theory suggests that agitation is affected by the pour height, so we went on to try the steady height method at different heights from the slurry. We found that the higher the pour, the slower the draw-down, and the higher the TDS — indicating that the higher pour results in more agitation.
While this is intuitive, it also contradicts Gagne’s theory, which predicts less agitation in the coffee bed if you pour high enough that the water splatters when it reaches the brewer. We’re planning more experiments shortly to confirm if this is the case, or if there’s something else happening when we pour from such a height.
The difference we found with the yo-yo brew, meanwhile, seems to be because the average pouring height was lower, compared to the brew from a steady height — rather than because of any effect of the up-and-down motion. The yo-yo brews tasted better not because the yo-yo method is better, in other words, but because the lower pouring height resulted in less clogging and channelling in the brew.
What these experiments make clear is that the pouring height is vitally important, and can make or break a brew. If pouring close to the surface means that the water doesn’t have enough energy to stir up the coffee bed, then extraction will be low and presumably uneven as a result. But pouring from too high up results in clogged filter papers and astringent, channelled brews. The ideal height will be different for each coffee, since some coffees seem to clog more easily than others. Unfortunately, this means that, until we know more, trial and error is the only way to find the right height for your brew.