Screening of musty-earthy compounds from tainted cork using water-based soaks followed by headspace solid-phase microextraction and gas chromatography–mass spectrometry

Abstract

Compounds responsible for musty-earthy off-flavours in cork, namely 2-methylisoborneol (MIB), geosmin (GSM), 2,4,6-trichloroanisole (TCA) and 2-methoxy-3-isopropylpyrazine (IPMP), were determined from tainted cork using water-based soaks followed by headspace solid-phase microextraction and gas chromatography–mass spectrometry (HS-SPME–GC–MS). The influence of the fibre coating used and of the extraction time and temperature were investigated for the joint analysis of MIB, GSM, TCA and IPMP. Considering the obtained results, an extraction time of 30 min at a temperature of 50 °C were fixed as experimental conditions, using a divinylbenzene/carboxen-polydimethylsiloxane/polydimethylsiloxane (DVB/CAR/PDMS) fibre. Quality parameters of the chromatographic method were obtained and good recoveries (117–128%) were found in spiked aqueous cork macerates. Using the same experimental conditions, the presence of guaiacol, 2,3,4,6-tetrachloroanisole (TeCA), pentachloroanisole (PCA), 2,4,6-tribromoanisole (TBA) and 2-methoxy-3,5-dimethylpyrazine (MDMP) could also be evaluated in a single chromatogram. From all the compounds analyzed in tainted samples, TCA and guaiacol were the only contaminants present and only TCA concentrations were found above its perception threshold in water.