Wednesday, January 5, 2011

Are There Objective Wine Faults?

While wine enjoyment is primarily about personal preference, there are certain 'faults' that are identified in the wine trade. Most have to do with intent--still wine shouldn't have spritz, dry wine shouldn't taste sweet, etc. Brettanomyces and its funky byproducts often fall in this group as well, though opinions vary. Oxidation is generally not good, but there are nonetheless oxidative styles of wine that are well-liked. Even volatile acidity (VA, similar to a bit of vinegar) has its place, especially in dessert wines.

I believe there are some faults, though, that have a purely physiological basis. Hence they are essentially objective; there is no context where noticing them is good. The only issue here is that not everyone has the same sensitivity--witness a debate about a wine being corked and this becomes clear. Here I'm thinking of a hypothetical scenario where a person is presented with two identical wines except for the fault--one that is clean, the other that has been dosed with the offending chemical. Assuming the chemical was in sufficient concentration to be smelled, virtually any person would prefer the clean wine.

High Levels of Mercaptans: A mercaptan is used in natural gas (at very low concentrations because most people are so sensitive) to give it a stinky aroma. Skunk spray also has several different mercaptans. The fact that mercaptans are a defense mechanism suggests they are almost universally offensive. I suppose some rotten cabbage, skunk, or rubber tire could be complexing at very low levels. But I doubt many people would find skunk-cabbage wine pleasing if presented with a non-skunky version of the same wine.

TCA/corked wine: At low levels, it seems simply to flatten a wine. At high levels, it's like a moldy basement. I don't think TCA could ever be a positive feature. Humans are programmed to generally avoid eating mold, and without fail when a corked wine is compared to a non-faulty version, the clean version is almost universally preferred.

Are there others? Geosmin, a byproduct of moldy grapes, is sometimes mentioned. But often enthusiasts enjoy earthiness, and moldy grapes can also give rise to certain 'noble' styles. I think what I describe as seaweed and like as a complexing aroma probably is also related to moldy grapes. I purposely left out volatile sulfides (non-thiol sulfur compounds), though, as these seem to be double edged swords, often contributing to varietal character lit black currant in Cabernet.

It does make me wonder about Brettanomyces byproducts. From an evolutionary standpoint, it makes sense that humans would avoid moldy and skunky smelling foods. So why not cow pasture smelling foods? Feces are not good to eat, hence people are repelled by the smell. But it seems at low to moderate levels if you did the thought experiment--one clean wine, then the same wine with some 4-EP--the latter might be preferred, though probably only by enthusiasts.

This is what makes this question tricky. If horse sweat and barnyard can be acquired tastes, what's to stop skunk and moldy rag? Farmyard is more positively evocative, and to me has a nice rustic and agrarian connotation. But does everyone feel this way? Maybe burning rubber tire and stewed cabbage are nostalgic for a person who grew up on a cabbage farm next to a tire manufacturing plant.

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