Dear Cecil: I was in the Costco liquor section when I happened upon a locked display case with three bottles inside (one whisky, one cognac, one I can't remember), each priced upwards of $2,500. I imagine anyone who bought and drank one of these would be heavily influenced by "buyer's bias" regarding the actual taste of the product; still, I'd think the difference would be great enough that an average, uneducated drinker could pick out the ultra-expensive bottle from a $30 one in a blind test. What can science tell us about why an extremely high-quality and typically older alcohol would be so much more pleasant to drink, and thus much more valuable? Morton Christopher

Cecil replies:

Science can tell us plenty about booze, Mort. However, the relevant discipline shifts as we rise in the price scale. At the low end, where we’re talking about beverages commonly drunk from paper bags, chemistry can easily demonstrate what separates rotgut from the decent stuff. Above a certain point, however, we find more useful insight in psychology, if you take my meaning. The question is where that shift occurs. In bitter moments I tend to say it’s around ten bucks a bottle, although having had a tasty if somewhat pricey Chateauneuf-du-Pape the other night I can see where you might objectively demonstrate that $100 was money well spent. But $2,500? Sorry, this is prima facie evidence of the madness of crowds.

With the exception of pure ethanol, alcoholic beverages are complex mixtures of chemicals derived from the raw materials plus the containers they’re aged and stored in. Variations in taste generally arise from differences in volatile organic compounds (VOCs), which readily vaporize at room temp when the container is opened and give the brew, vintage, or what have you its characteristic smell — not the common term, particularly among wine enthusiasts, but let’s call a spade a spade.

The VOCs potentially found in alcoholic beverages make for a long list. Most of the terms mean nothing to the nonspecialist, but since you asked, here are some things you might detect if your man cave is equipped with a mass spectrometer:

Proanthocyanidins, tannin colloids, and flavan-3-ols all contribute bitterness and astringency to wine.

“Nuttiness,” considered a desirable quality in Scotch whisky, can often be traced to the presence of pyrazine compounds, whereas 2-furanmethanol imparts an aroma variously reminiscent of popcorn, earth, and feet.

Phenols contribute peatiness to Scotch, and Scotches made from malt smoked over peat fires acquire phenolic traits so distinctive chemists can sometimes identify the original peat bog. When researchers analyzed 1890s Scotch recovered a few years ago from Ernest Shackleton’s Antarctic camp, its phenol profile was correctly traced to a bog in the Orkney Islands.

Still, while we know in a general way which VOCs are associated with what taste, that’s a long way from saying we can detail with any confidence the chemical differences separating an award-winning beverage from an OK one.

In many cases these differences are minute. For example, the subtle taste of “greenness” in a Sauvignon Blanc, an undesirable quality in other varieties of wine, arises from methoxypyrazine compounds, detectable by humans in the parts per trillion. It’s surely also true that taste is a result of the interplay between multiple VOCs, some of which chemists have yet to identify. The best means of judging quality, therefore, remains the human nose and palate.

These make for an imperfect instrument. Nowhere is this more evident than in the world of wine tasting:

In 2005 judges at the California State Fair Wine Competition were unknowingly served certain wines three different times on different days. Individual tasters’ scores for the same wine varied widely, in some cases from 87 points (nothing special) to 95 (primo).

In a blind tasting, 54 students in the wine program at the University of Bordeaux were tricked into perceiving a white wine as a red simply by adding food coloring to it.

Con man Rudy Kurniawan fooled wine experts from around the world with his counterfeits of rare wines made with cheap Napa Valley product and photocopied labels. He was finally tripped up when he tried to auction faux vintages dated decades before the wine in question was ever actually produced.

Does that mean alleged differences in alcoholic beverages are BS? Depends on what you consider differences. When nonprofessional tasters were trained to use a standardized whisky-tasting vocabulary and then given samples of 40 blended Scotch whiskies, their assessments generally corresponded with the four categories of whisky being tested (deluxe, standard, cheap, and West Highland). In a separate study, the four categories were themselves found to have distinctive chemical signatures. In other words, it was possible to sense broad variations in quality, and those variations had a chemical basis.

On the other hand, consistently distinguishing a presumably exquisite $2,500 bottle from a merely excellent $100 one … eh, maybe somebody with an unusually sensitive palate could do it. You or me? That I doubt.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.