Monitoring tea fermentation/manufacturing by direct analysis in real time (DART) mass spectrometry

Karl Fraser, Geoff A. Lane, Don E. Otter, Scott James Harrison, Siew-Young Quek, Yacine Hemar, Gitte Susanne Rasmussen

Research output: Contribution to journalJournal articleResearch


Factors such as fermentation methods, geographical origin and season can affect the biochemical composition of tea leaves (Camellia sinensis L.). In this study, the biochemical composition of oolong tea during the manufacturing and fermentation process was studied using a non-targeted method utilising ambient ionisation with a direct analysis in real time (DART) ion source and mass spectrometry (MS). Caffeine dominated the positive ionisation spectra throughout the manufacturing process, while the negative ion spectra collected during manufacturing were rich in ions likely to be surface lipids. Correlation analyses on the spectra revealed two volatile compounds tentatively identified as indole and geranic acid, along with ammonium and caffeine clusters/adducts with geranic acid that increased in concentration during the fermentation stages of the process. The tentative identifications were assigned using a combination of DART-ion-trap MSn and DART-accurate mass MS1 and MS2 on tea samples and standard compounds. This study highlights the potential of DART-MS to rapidly monitor the progress of complex manufacturing processes such as tea fermentation.
Original languageEnglish
JournalFood Chemistry
Issue number3
Pages (from-to)2060-2065
Publication statusPublished - 2013
Externally publishedYes


  • Direct analysis in real time (DART)
  • Mass spectrometry
  • Profiling
  • Fermentation
  • Tea manufacturing
  • Tea
  • Caffeine
  • Geranic acid

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