title: Monitoring tea fermentation/manufacturing by direct analysis in real time (DART) mass spectrometry.
abstract: 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 MS(n) and DART-accurate mass MS(1) and MS(2) 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.
authors.affiliation: AgResearch, Private Bag 11008, Tennent Drive, Palmerston North 4410, New Zealand. karl.fraser@agresearch.co.nz
authors.forename: Karl
authors.initials: K
authors.lastname: Fraser
authors.forename: Geoff A
authors.initials: GA
authors.lastname: Lane
authors.forename: Don E
authors.initials: DE
authors.lastname: Otter
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Harrison
authors.forename: Siew-Young
authors.initials: SY
authors.lastname: Quek
authors.forename: Yacine
authors.initials: Y
authors.lastname: Hemar
authors.forename: Susanne
authors.initials: S
authors.lastname: Rasmussen
mesh_terms: D028241:Camellia sinensis / Q000737:chemistry*; D005285:Fermentation; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D018515:Plant Leaves / Q000737:chemistry*
keywords: Caffeine; Direct analysis in real time (DART); Fermentation; Geranic acid; Mass spectrometry; Profiling; Tea; Tea manufacturing