Chemical Marker Sotolon Found in Premox Wines

Following up on the previous blog about How to Prevent Premox in Wines, there appeared another article published by Professor Denis Dubourdieu and Dr. Valérie Lavigne, which can be found in it's entirety at The New Bordeaux entitled The premature oxidative ageing of wine. The article is very accessible and entertaining in parts but also addresses the profound question of premature oxidative (premox) aging in white wines.
Beginning in 2000, Professor Denis Dubourdieu and Dr. Valérie Lavigne, using gas chromatography, conducted research into the aroma compounds that constitute a wine suffering from premox. Three compounds methional, phenylacetaldehyde and o-aminoacetophenone had already been identified in prematurely aged dry white wines but not all premoxed wines contain these compounds. One compound, sotolon was identified by Dubourdieu and Lavigne to contibute to the aroma of all premoxed wines. Sotolon is a volatile heterocyclic compound with an intense curry aroma with a detection threshold in dry white wines on the order of 7 μg/L (7 ppb). The sotolon molecule has an asymmetrical or chiral carbon atom as shown in the depiction below.

The chiral carbon in sotolon means that it has two enantiomeric forms, R and S. The R and S forms of sotolon confer different attributes to the molecule. (S)-sotolon is much more readily detected and the odor is reminiscent of curry and walnuts, while(R)-sotolon smells only of rancid walnuts.
The authors go on to write that since sotolon is formed by a reaction between α-ketobutyric acid, present in all wines, and acetaldehyde, whose concentration is increased by oxidation, it is absolutely essential for winemakers to avoid acetaldehyde production at all stages of white wine production.
References:
1. Denis Dubourdieu and Valérie Lavigne, The premature oxidative ageing of wine, The New Bordeaux.
2. Chemical structure and IUPAC nomenclature of sotolon retrieved from Chemicalize.org. All structures were drawn by the freely available drawing program from ACD Labs called ACD/ChemSketch Freeware.