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.