Legend has it that Dom Perignon shouted, “I’m tasting the stars,” after sipping one of his famed bubbly champagnes.

Now, three centuries later, Columbia neuroscientist Charles Zuker and colleagues have discovered that the tingle we get from the carbonation in champagne, soda, and seltzer water comes not just from the feel of the bubbles on our tongues, but mainly from the activation of sour taste receptor cells triggered by the carbon dioxide inside the bubbles.

The researchers discovered that the tongue detects the gas with enzymes tethered to the exterior of the tongue’s sour-sensing cells. Once the enzyme detects CO², the sour-sensing cells send a message to the brain, which interprets the gas as a sour taste.

The discovery also clears up the mystery of the “champagne blues,” the depressingly flat taste of champagne experienced by mountaineers at high-altitude summits. The enzyme responsible for the taste of carbonation – a carbonic anhydrase – is blocked by drugs taken by mountaineers to prevent acute mountain sickness.

Though the enzyme enhances our appreciation of champagne, the sensation is most likely an accident of evolution. The primary role of the enzyme, Zuker says, probably is to help maintain the pH balance of the taste cells.

So, what’s the sense in studying the taste of carbonation?  The findings help reveal how the gustatory system – with only five taste qualities (sweet, sour, salt, bitter, and umami) – can orchestrate a multitude of other flavors, like carbonation. Ultimately, that will help us decipher the key task of our senses: how the brain transforms the external world into internal representations.

For more information about the study, go to http://www.hhmi.org/news/zuker20091015.html.

Dr. Zuker is a professor in the Departments of Biochemistry & Molecular Biophysics and Neuroscience and an investigator with the Howard Hughes Medical Institute.