optimization of headspace solid-phase micro-extraction (hs-spme) for analyzing soy sauce aroma compounds via coupling with direct gc-olfactometry (d-gc-o) and gas chromatography-mass spectrometry (gc-ms)

The aim of this study was to develop an effective analytical procedure to analyse the aroma-active compounds of soy sauce using headspace solid-phase micro-extraction (hs-spme) coupled to gas chromatography-mass spectrometry/olfactometry (gc-ms/o). optimization of spme focusing on type of fibre, exposure time, extraction temperature and ionic strength was supported by gas chromatography-mass spectrometry (gc-ms). the optimized hs-spme conditions were as follows: carboxen/polydimethylsiloxane (car/pdms) fibre, nacl concentration of 270 g/l, extraction temperature of 45 °c and 30-min exposure time. under these conditions, 25 aroma-active compounds were detected in soy sauce by hs-spme-gc-o. 2-methylbutanal (malty), 3-(methylthio)propanal (cooked potato-like), dimethyl trisufide (sulfury, cooked onion), 2-methoxyphenol (smoky) and 2-phenylethanol (flowery) were the most intense. the overall odour impression of the car/pdms-fibre-derived spme extract detected via human sniffing resembled that of original soy sauce. the intensity of aromas detected by d-gc-o correlated well with the total peak area of gc-ms analysis. thus, spme coupled with d-gc-o offers an automated facile method to allow in situ optimization of spme performance and ultimately effective analysis of aromas.