Quantification of cork off-flavor compounds in natural cork stoppers and wine by multidimensional gas chromatography mass spectrometry

Trace-level analysis of cork off-flavor compounds considered as responsible for typical [2,4,6-trichloroanisole (TCA)] and atypical cork taint [geosmin (GSM); 2-methylisoborneol (MIB); 3-isopropyl-2-methoxypyrazine (IPMP); 3-isobutyl-2-methoxypyrazine (IBMP); 3,5-dimethyl-2-methoxypyrazine (MDMP)] was achieved for cork soaks and wines for concentrations below odor threshold (MIB only in cork soaks). The analytical approach was based on headspace solid-phase microextraction and heartcut multidimensional gas chromatography with tandem mass spectrometric detection. Quantification was done using a stable isotope dilution assay. Individual cork stoppers with varying sensory off-odor descriptions were analyzed. In particular, IPMP and IBMP correlated with the cork stoppers described with green attributes. MDMP was found in samples described as dusty-musty or nutty-like. In a migration study, transport of off-flavor compounds from affected cork stoppers into the corresponding wine could be observed after a storage period of 13 months. Multivariate statistics on the wines' sensory analysis and chemical data showed a good correlation of the individual off-flavor compound concentration, its sensory description and the off-flavor perceived in the wine.