Stripping of aroma compounds during beer fermentation monitored in real-time using an automatic cryotrapping sampling system and fast gas chromatography/mass spectrometry

摘要: Improvements are reported for a recently described instrument made up of an innovative headspace sampling and injection system built using longitudinally modulating cryogenic mounted around the loop two-position injector, which had been hyphenated to low thermal mass gas chromatograph. Replacing bare capillary used previously cryotrapping by coated opened additional potential fields application since more volatile analytes, with boiling points above 140 °C instead 190 °C, could now also be quantitatively cryotrapped. Detection spectrometer flame ionization detector enabled investigation dynamic processes that release complex mixtures compounds in widely varying amounts. The performance improved was illustrated monitoring real time, 5 min resolution, stripping aroma fermentative carbon dioxide during beer fermentation. Compounds derived from hops, including monoterpenes, sesquiterpenes some esters, present initial wort but not formed subsequently, were observed stripped off early fermentation process. Fusel alcohols earliest yeast metabolism, found released significant amounts wort. More than ten fermentation-derived esters later into Although similar, their kinetics exhibited clear differences consequences different biosynthetic production rates physical–chemical properties. curves further how they can lead elucidation origin discussed.