What Carbonation Tastes Like

It’s a pretty common sentiment that flat beer doesn’t taste very good – but why is this? I’ve never really thought about the reason, but apparently some people have... On my way home from work yesterday, I caught a story by NPR about a new study on carbonation. Of course I immediately thought about beer (didn’t everyone?).

Turns out the way we experience carbonation has more to do with taste than it does the feeling of the bubbles. When we drink a carbonated beverage, the very same taste buds that detect acidity/sourness also detect carbonation. But the way they do it is interesting. I suspect most people (including myself) tend to think that the appeal of carbonation is the bursting of those little bitty bubbles [cue Don Ho]. It’s actually an enzyme on those taste buds that reacts with CO2 to create acid.

…researchers found that sour-sensing cells have a certain enzyme on their surfaces, according to a report on the research in the journal Science. This enzyme, carbonic anhydrase 4, belongs to a family of enzymes that respond to carbon dioxide.

"This is a particularly interesting carbonic anhydrase. It's actually stuck on the outside surface of cells," says Ryba, who says it appears to cause a reaction with carbon dioxide that generates acidity just outside the sour-sensing cells. "That's why we think carbon dioxide causes a taste response."

Earl Carstens of the University of California, Davis, who has studied the perception of carbonation, says that when he drinks soda, he normally thinks about the tingling and burning sensation that's slightly pleasant at the back of the throat — feelings he says are caused by carbonic acid triggering sensory pathways that register things like pain.

"But this paper says there's also a distinctive taste component that you should be aware of, too," Carstens says. "And it's distinctly different from just regular water."

Carstens says that he and other researchers have long known that the carbonic anhydrase enzyme must somehow be involved in the enjoyment of carbonation, because mountain climbers who take altitude-sickness drugs that block this enzyme have reported that champagne and other bubbly beverages taste like dishwater.

So really, flat beer doesn’t taste that great because it’s missing the acidity we get when drinking carbonated beer. That might also explain why I enjoy dry, carbonated mead so much more than sweet mead. The acidity is refreshing and balances out the beverage. Pretty cool!

* Afterthought - for those of you interested in more information on this, here's a slightly more involved article on Science Daily.