Dekkera (Brettanomyces) bruxellensis, commonly referred to as Brett, is a
spoilage yeast found in beer and wine. The yeast creates off-odours which are described as ‘animal’ (e.g. horsey, sweaty, mousy) or ‘phenolic’.

To identify the marker compounds associated with Brett spoilage in a red
wine sample from Bordeaux, TargetView™ data-mining software was employed to interrogate the sample’s GC/MS profile.

For this purpose a specific Brett compound library was created within TargetView to screen for the marker compounds associated with this spoilage yeast.

Method

For this application, an SPE-tD cartridge was introduced to a vial containing 20 mL wine and agitated for 1 hour. After sampling, the bar was washed and placed in a TD tube, desorbed and analysed via GC/MS. Full method details for both the wine and a fruit juice sample are discussed in Markes International application note TDTS 88 (Enhancing olfactory profiling of fruit juices and wine using complementary analytical thermal desorption techniques). The Brett target library contained the compounds listed in the table.

Results

The figure below shows the TargetView display window in which the lower window displays  the identification (and match coefficient) for a specific compound (4-ethyl phenol) in the sample analysed.

The Bordeaux sample shows positive hits for several Brett target analytes including the primary ones of 4-EP, 4-EG and 3-
methyl butanoic acid, which are
highlighted with arrows in the table below.

Identification of "unknowns" extends the performance and usefulness of TargetView.

This can even be achieved if analytes are seen to be co-eluting.

This is described in full in the application note (ANTV14), which can be downloaded.

Conclusion

TargetView is an effective screening tool for the identification of both target and unknown compounds within complex
GC/MS TICs. In this example the primary marker compounds 4-ethyl phenol (4- EP), 4-ethyl-2-methoxy phenol (4-EG) and 3-methyl butanoic acid have been
identified in the Bordeaux wine sample, indicating the presence of the spoilage yeast Dekkera (Brettanomyces) bruxellensis.