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

• Published in: Food chemistry 2013-12, Vol.141 (3), p.2060-2065
• Main Authors: Fraser, Karl, Lane, Geoff A., Otter, Don E., Harrison, Scott J., Quek, Siew-Young, Hemar, Yacine, Rasmussen, Susanne
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Caffeine; Camellia sinensis; Camellia sinensis - chemistry; Direct analysis in real time (DART); Fermentation; Geranic acid; Mass spectrometry; Mass Spectrometry - instrumentation; Mass Spectrometry - methods; Medical sciences; Neuropharmacology; Pharmacology. Drug treatments; Plant Leaves - chemistry; Profiling; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease); Psychology. Psychoanalysis. Psychiatry; Psychopharmacology; Tea; Tea manufacturing
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2013.05.054

•Rapid ‘real-time’ method developed for monitoring tea manufacturing by DART–MS.•Detected significant changes in the formation of volatile components during tea manufacturing.•Demonstrated the potential of DART-MS to rapidly monitor the progress of complex manufacturing processes. 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.