When you pour a glass of beer, a frothy cascade of fizz rises to the top; as more and more tiny bubbles coalesce, they form a nose-tickling layer of foam.
At first, that frothy stream of carbonation seems endless. But just how many bubbles can emerge from a glass of beer before it goes flat?
Gérard Liger-Belair, a professor of chemical physics at the University of Reims Champagne-Ardenne in France, had previously explored this effervescent subject in Champagne, calculating that one flute produces about 1 million bubbles.
Recently, Liger-Belair peered into the depths of beer glasses and found that they produce twice as many bubbles as Champagne — with up to 2 million bubbles popping in a half-pint glass, according to a new study.
Beer is typically made of four ingredients — malted cereal grains, hops, yeast and water — which are then fermented. This process breaks down carbohydrates to produce alcohol, sugars and carbon dioxide (CO2).
When beer is bottled or canned, additional CO2 is added, creating pressure in the container. Once the seal on a can or bottle is broken, the liquid becomes supersaturated with CO2, which is then released as tiny bubbles.