Sparkling wine – or beer, or soda, or seltzer* – triggers an unmistakable set of sensations, addictive or repellent depending on your predilection. But is that sensation a taste? A physical sensation? Something else? Probably some combination of the above, though figuring all of that out is trickier than you might imagine.
First, the bubbles in sparkling wine are carbon dioxide, either the product of yeast fermenting a last little bit of sugar in the bottle or mechanical carbonation with a tank of pressurized gas. Carbon dioxide plus water makes carbonic acid: CO2 + H2O ⇌ H2CO3 . Acids, by definition, are molecules with hydrogens which can and do pop on and off when dissolved in water. If the hydrogens tend to disassociate themselves easily, you’re dealing with a strong acid (e.g. hydrochloric or sulfuric) best used for cleaning glassware or dissolving an inconvenient corpse. If only a small number of hydrogens hop off at any one time, you’re dealing with a weak acid. Carbonic acid, needless to say, is a weak acid, or else seltzer water would be an industrial solvent rather than a cocktail mixer. Chemists were associating the perception of sourness with those free hydrogen ions back at the turn of the twentieth century, but they’re not sufficient to explain sourness alone, and twenty-first century chemists are still trying to work out the remainder. The ongoing search for a complete explanation of sourness is one of those excellent examples of how very simple daily phenomena can end up being unexpectedly complicated when scientists try to explain them in terms of chemistry and biology.
Second, the bubbles in sparkling wine are mechanical stimulation. If you stick your hand into a glass of sparkling water, you’ll feel the “prickle” of bubbles bursting along your skin, and your tongue and the interior of your mouth receives the same sensation. That’s not surprising.
A third component of how we sense carbonation is surprising, or at least it’s surprising to me as a carbonated beverage-lover. Carbonation appears to trigger nociceptors, the specialized receptors we have for sensing pain. Carbonation is, physiologically speaking, irritating.
Maybe it’s not surprising to find that Champagne belongs on the list of painful foods along with super-spicy cuisines and overly hot tea. Or, rather, a goodly number of people seem to find Champagne painful for numerous different reasons. Drinking Champagne and enjoying it is a social skill, but everyone seems to know at least someone who really doesn’t like the stuff. Some are folks who don’t enjoy wine or alcoholic beverages at all, and some are surely like me in liking sparkling wine but having mainstream Champagne sullied by thoughts of what other, more interesting wines could have been purchased for the same $40. Perhaps some of them are also troubled by unusually high sensitivity to the negative sides of carbonation. A recent study of how consumers perceive small differences in degree of sparkling wine carbonation attests that individual tasters have different thresholds for feeling – and maybe feeling discomfort from – carbonation. Occam’s razor still says that “Champagne”**-haters are more likely suffering from a combination of low-quality bubbly, ill-advisedly sweet food pairings, and excess consumption. But heck; the simplest answer isn’t always the correct one. Just look at the sensation of sparkling.
As for me, I’m strongly in the pro-carbonation camp. I also eat 100% unsweetened chocolate straight-up, take strong tea and coffee black, and eat bitter greens for breakfast all of which, I’m told, are rather painful suggestions to many people. Perhaps these statements are not unrelated?
For more on sparkling wine physics: http://palatepress.com/2012/12/wine/champagne-physics-or-what-science-can-tell-you-about-drinking-your-bubbly/
For more on Nobel prize-winning sparkling wine microbiology: http://palatepress.com/2012/11/wine/yeast-martyrdom-toasty-flavors-in-your-sparkling/ and http://palatepress.com/2016/10/wine/nobel-winning-research-also-explains-the-taste-of-champagne/
*Or carbonated foods. This soup? Fermenting kimchi? Pop rocks?
**In quotes only because people who object to “Champagne” may be reacting to negative experiences of other non-Champagne sparkling wines and I’m not interested in picking a fight with the CIVC.