It’s a problem every beer drinker knows intimately. You bring a six-pack to a party. Throw it down in the cooler, less one can. Crack that can open with the familiar hiss and suddenly you find yourself covered in foamy beer. Lore tells us that tapping a beer with the tip of your finger will save you from this sticky fate, but researchers at the University of Southern Denmark put this theory to the test with the help of 1,031 cans of pilsners donated by a nearby brewery.
Elizaveta Sopina and her team set out to test if tapping a beer before opening it will reduce its tendency to foam over. You see, foamy, exploding beer is the result of trapped carbon dioxide becoming agitated—or “desaturated” in science-speak—before it’s opened. Tiny bubbles, which are typically released when the can is opened to produce foam, instead are released inside the can. When the beer is opened, the bubbles are all worked up and ready to party, and that’s why you now have beer on your shoes.
As the MIT Technology Review points out, the method Sopina and her team put forward involved dividing the beers into two groups—shaken and unshaken—and then dividing those beers into ones that were “tapped” before opening and ones that were not. Beers were shaken for two minutes at 440 rpm, which was meant to mimic ten minutes on a bike—apparently a popular means of beer transportation in Denmark. They then opened the beers and measured the amount of liquid lost to foaming.
The shaken beers, not surprisingly, foamed more than the unshaken beers. However, the “tapped” beers showed meaningful difference when compared to the untapped ones, since the tapping did not involve much more than flicking a beer three times on the side of the can. Sopina and her team suggest that this method did not provide enough energy to dislodge bubbles and instead that the energy was absorbed by the can, while also adding that “if most bubbles are located in the bulk liquid, the surfacing of the wall-adhered bubbles by flicking would be insignificant compared to the rapid surfacing of the bubbles in the bulk liquid.”
Translation: Three flicks is not enough.
And while Sopina’s research is limited to the effect that shaking and tapping has on “preventing, or, at least, minimizing beer fizzing” that “is both socially and economically desirable,” the study admits that some methods to reduce fizzing—such as heating and cooling—might affect the flavor and texture of a beer. Sounds like another 1,000 beers are in order.