Of all alcoholic drinks, beer alone can boast of a dense and lingering mousse topping its liquid depths. Beer’s lively texture and fluffy foam have been admired since ancient times. All the more amazing is the collection of chemical miracles that make that foam happen.
Sure, many drinks have bubbles. In champagne and other sparkling wines, these can be enchanting—glittering, lazily drifting their way up to the surface—and then they simply self-destruct. Wine, wonderful as it can be, lacks the unique mix of components needed for bubbles to form sustainable foam. In cocktails, meanwhile, you must delve into the egg-whites niche—think gin fizz or pisco sour—to find a simulacrum of the impressive head on a well-poured beer.
Carbonation strongly contributes to aroma. Bubbly beverages contain a rich mix of compounds that give off twice as much aroma as still drinks, and this is true for beers as well. It’s also why most wine needs an in-curved glass with a lot of headspace to capture its volatiles.