Then why have we been doing it all this time?

By Tim Nelson
December 11, 2019
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If you’re experienced in the art of cracking open a cold one, you may be in the habit of tapping the top of a beer can to try and prevent the loss of some of those precious suds. But as the results of a new, strenuous scientific study indicate, it seems that this tried and true method for minimizing beer loss is actually just bunk.

That’s according to research out of the University of Southern Denmark, where a team of scientists analyzed what happens when Carlsberg is shaken vigorously and then opened. To conduct the experiment, they loaded about half of the 1,031 330-milliliter cans they collected onto a mechanical shaker for two minutes in order to simulate the experience of beer jostling around a bike, Denmark’s de facto national mode of transportation. An equal number of cans were unshaken, and half of the beers from each of those groups were tapped with a finger three times to simulate that seemingly foolproof method of beer loss prevention.

Testers, who didn’t know whether cans were shaken or unshaken and tapped or untapped, were then tasked with opening each beer and measuring how much was lost. The results, published by Cornell University’s physics department, showed that shaken beer cans lost well over six times as much beer (3.45 grams) as unshaken ones (0.51 grams) on average. But the more remarkable finding was that there was no statistically significant difference whatsoever between tapped and untapped cans, whether shaken or left still.

Why is that? In speaking with New Scientist, study co-author Elizaveta Sopina postulates that tapping beer doesn’t do anything to help bubbles rise to the top. The progress of bubbles might be impeded by the barley proteins found in beer, which usually have the effect of stabilizing bubbles.

So there you have it: you’ve potentially wasted minutes of your life tapping cans of beer to almost no effect. It seems like the only solution to not wasting a beer is to have a little patience.