Carbonation and the pain of Champagne

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.

Analytical chemistry says that Scotch whiskys really are different

Short: The Scotch industry has new scientific evidence that different single malts and blended Scotch whiskys are complex and distinctly different from one another. (Unlike, the suggestion might be, some mass-produced American “craft” whiskeys.)

Long: You can learn a lot about a field by its acronyms. Acronyms arise for awkward word-strings that a certain flavor of professional uses often but everyone else uses infrequently enough for English not to have a better and less cumbersome word for whateveritis. Winemakers talk about MOG: Material Other than Grapes.* MOG is interesting because winemakers are generally trying to get rid of it. Mass spectrometry experts talk about NOM: Natural Organic Material. Wine is a NOM. NOM is interesting because it’s replete with myriad compounds at miniscule concentrations and therefore helps spectrometer-ers figure out how good their techniques are. Mass spec is interesting to NOM-lovers because its a good way to learn about the composition of the NOM. And who are NOM-lovers? You are. Wine is a NOM. So is whisky.

A batch of analytical chemists from Scotland has just published a new article (open-access) in the Journal of the American Society of Mass Spectrometry (no, I didn’t know that existed, either) applying a particularly sensitive and wide-seeking version of mass spectrometry (more detail on what that means below**) to quantify the complexity of single malt and blended Scotch. Across 85 different commercial whiskies, they found 4271 unique molecular fingerprints – not precisely the same as identifying 4271 unique molecules because of the kind of data mass spec generates, but definitely evidence that whiskies are very, very complex mixtures. Only 407 of those probably-molecules were common to every whisky, and only about a thousand were common to 75% of the samples. In short, whiskys are highly variable, and perhaps even more complex than you’ve been imagining.

That result should please the SWRI – an acronym you’ll recognize if you’re in the spirits trade and that I should otherwise explain stands for the Scotch Whisky Research Institute – who provided funding for the study. A cadre of American “craft” whiskeys have been attacked from many quarters (including NPR and Serious Eats) for being remarkably similar across brands and price points and, not unrelatedly, for originating in the same industrial production facility in Indiana. Funding analytical chemists in Edinburgh looks like a Scottish move to assert that Scotch is the real deal, and maybe that consumers’ money is well-spent trying honest-to-goodness different brands.

That implication brings us back to the NOM. For the chemists, the choice of NOM isn’t precisely inconsequential – I know that the lead author on this paper is a NOM-lover himself, and they obviously wouldn’t have won funding from the whisky industry if the lab was studying, say, latex wall paint. But this study is published in a journal of mass spectrometry, and at least a large fraction of the point here is about demonstrating the prowess of their hardware and analytical methods. And that point has to do with the kind of data this study provides. We know that whiskys contain a lot of unique molecules, and we know that different whiskys contain lots of different molecules. What we don’t know is anything about how or whether those molecular differences translate to sensory differences. But since the SWRI is interested in Scotch, not just in NOMs, I suspect that we may be seeing that sensory study soon.

 

* Material other than grapes that ends up in collection bins with grapes, not all non-grape matter everywhere; winemakers might get accused of singlemindedness, but they’re not that bad.

**Mass spectrometry, broadly speaking, is a method to identify chemicals by their mass which, given that every kind of atom (think the periodic table) has a unique mass and molecules are defined by their atomic composition (and how those atoms are arranged, which makes life more complicated), makes mass spec something approaching a molecular fingerprint. Mass spectrometry, narrowly speaking, is any one of many, many different versions of that general principle, all of which have their own acronyms. These folk sent their 85 samples of fine Scotch through ESI-FT-ICR MS, which means electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry, which means that the scientists didn’t have to decide in advance which compounds they wanted to look for.

Tracing down tobacco aromas in aged brandies

I’ve become so accustomed to fermented beverages having flavors completely unrelated to their starting ingredients that I all too easily forget that there’s anything strange about it. And then I introduce someone to wine tasting for the first time and find myself having to explain that, yes, the wine tastes like cherries and no, they don’t put cherries in the wine to get it to taste that way. (But also sometimes that, yes, the wine tastes like oak, and yes, they do put oak in the wine, or wine in the oak, to make that happen.)

Wine and aged brandies, like Cognac, sometimes taste like tobacco. No one adds tobacco to them.* What happens instead is an example of what you could liken to chemical convergent evolution. Brandies can indeed contain odiferous molecules also characteristic of tobacco flavors. But those molecules appear to come from the breakdown of compounds present in grapes, not from any exposure to tobacco (and, needless to say, the tabanones in tobacco don’t come from grape-derived compounds).

Megastigmatrienone is more conveniently called tabanone. Or, more properly, megastigmatrienones are are more conveniently called tabanones, because the designations apply to a group of similar molecules. They seem to show up in wine because carotenoids – the highly pigmented class of antioxidant molecules you’ll recognize from it’s best-known carrot-colored member, beta-carotene – can become megastigmatrienones under appropriately acidic conditions. The precise pathway from grape-derived carotenoids to tobacco aromas remains something of a mystery. It seems that brandies, distilled from grape wine, end up with concentrated amounts of tabanones or precursors which then have an extra chance to develop into tabanones during barrel aging.

That mystery makes all the more interesting a recent study to quantify tobacco aroma molecules in Cognac and Armagnac**. Most of the (many) examples they tested contained some tabanones. Concentrations varied widely, but the Armagnacs averaged higher than the Cognacs and – evidently to everyone’s surprise – the aged rums thrown in for comparison ranked even higher than the Armagnacs. Much higher, in fact, even though the molasses from which rum is distilled doesn’t contain significant amounts either of tabanones or of the identified precursor molecules present in grapes.

So, why is this interesting?

  1. Tobacco aromas in aged spirits are evidently not just coming from molecules originally present in grapes.
  2. The oak barrels used for aging rum, as well as various brandies, probably contributes substantially to tobacco aromas in those spirits by leaching precursor molecules out of the wood and into the spirit and providing favorable conditions for their development.
  3. The researchers behind this study seem to think that their new-and-improved means for quantifying particular variants of tabanones could be useful for distinguishing Cognac from Armagnac, presumably to defend against passing one kind of spirit off as another. Looking at the enormous variation in tabanones between one kind of Cognac and another, or one kind of Armagnac and another, this suggestion seems frankly ridiculous. Chemistry backs up tasting experience: individual bottlings vary dramatically in the presence or absence of tobacco aromas as a defining characteristic. Yes, Armagnacs beat out Cognacs on average, but averages don’t help distinguish individuals when individual variation is so high. A more interesting use of this research, I think, is the starting point it provides for thinking about how barrel-aging adds to tobacco aromas, in spirits and possibly in wines. I suspect that the people who produce these spirits already have a lot to say on that point. Joining their knowledge with some well-placed chemical analyses could improve everyone’s understanding of how tobacco aromas happen and how to manipulate them.

 

* Ewwww.

**Camper English has drawn up a helpful comparison between Cognac and Armagnac at Alcademics.com.