Sensory and analytical re-evaluation of “Brett character”

Worldwide wine production has been significantly affected by Brettanomyces bruxellensis spoilage. This alteration, sometimes referred to as “Brett character”, results in the production of several volatile compounds and a large spectrum of flavours and aromas. Ethylphenols (namely 4-ethylphenol and 4-ethylguaiacol) are the best-known markers of this defect with a commonly used aggregate detection threshold of about 400 μg/l. Fifty-one Bordeaux red wines were tasted with the aim of wine profiling for commercial purposes. Ethylphenol concentrations of wines were very poorly correlated to the corresponding tasting notes. Sensory analysis was employed to demonstrate the complexity of “Brett character”. A masking effect of isobutyric acid and isovaleric acid on the detection of ethylphenols in wine was proven. This partly explained the poor correspondence between ethylphenol concentrations and presence of “Bretty” descriptors.