Know Your Wet Cardboard Smells

MLipton

Mark Lipton
Cutting edge research from some German chemists has at long last put to rest the question of what is meant when someone smells "wet cardboard" in a wine. Czerny and Bttner analyzed wet cardboard by aroma extract dilution analysis and high resolution gas chromatography and found that the "classic" woody cardboard smell came from E- and Z-non-2-enal and an unidentified molecule. Overall, 36 different components of wet cardboard smell were found, including the ever-popular 4-methylphenol (Brett infection, anyone?). Dry cardboard, by contrast, released only a few of these molecules. Remember, you heard it here first!

J. Agric. Food Chem., 2009, 57 (21), pp 99799984

DOI: 10.1021/jf901435n

Your humble scribe,
Mark Lipton
 
Well there was a mouldy component in the large variety [37 in the version seen] of 'cardboard' smells which was not identified by chemical name in the abstract but would probably be the closest 'aroma' to TCA without presumably being that compound - which surely they would otherwise have highlighted.

Interesting that they identified 4-ethyl phenol [one of the main brett products] along with 4-methyl phenol in the mix. Might this also provide a weak 'cardboard aroma linkage' to explain why low level brett [as well as certain thiols and disulphides] has apparently been confused with low level haloanisole contamination even though TCA wasn't mentioned as one of the 37 compounds isolated in this cardboard analysis?

Interesting too that the scientists showed it was when the cardboard became wet that the aromas became noticeable. Indeed Czerny and Buettner report that the aroma profile changed drastically when the cardboard was moistened, becoming intense and yucky as in woody and musty with very pronounced fatty and moldy highlights".

Intense, yucky, woody, musty and mouldy seems to be a fair description of 'wet cardboard' TCA even if that compound wasn't actually present in the analysis.
 
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