The secret to why seltzer tastes good, discovered.

"Tasting fizz begins with a special protein that’s tethered to sour-sensing taste cells on the tongue, researchers report in the Oct. 16 Science. This protein, the enzyme carbonic anhydrase 4, splits carbon dioxide into bicarbonate ions and free protons, which stimulate the sour-sensing cells.

Scientists have long thought that the taste of carbonated beverages emerged from the physical bursting of bubbles on the tongue, says study author Charles Zuker, a neuroscientist now at Columbia University who did the work while at the University of California, San Diego. But bubbly drinks still taste distinctly carbonated when they are imbibed in a pressure chamber where bubbles don’t burst.
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Bachmanov calls the new work “elegant.” Taste “is a very challenging system to study,” he says. “Everything is very small but very complex.”

In the bigger picture, tasting carbonation may have allowed animals to sense CO2 produced in foods that had fermented or gone bad, akin to how bitter-sensing taste cells warn of potential toxicity, says Zuker."

Aren't you glad scientists are working on this?