Climate and Processing Effects on Tea (Camellia sinensis L. Kuntze) Metabolome: Accurate Profiling and Fingerprinting by Comprehensive Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry.

Federico Stilo,Joshua Morimoto,Giulia Tredici,Chiara Cordero,Albert Robbat,Carlo Bicchi

doi:10.3390/molecules25102447

Federico Stilo, Joshua Morimoto + Show 4 more

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https://doi.org/10.3390/molecules25102447

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Abstract

This study applied an untargeted–targeted (UT) fingerprinting approach, based on comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOF MS), to assess the effects of rainfall and temperature (both seasonal and elevational) on the tea metabolome. By this strategy, the same compound found in multiple samples need only to be identified once, since chromatograms and mass spectral features are aligned in the data analysis process. Primary and specialized metabolites of leaves from two Chinese provinces, Yunnan (pu′erh) and Fujian (oolong), and a farm in South Carolina (USA, black tea) were studied. UT fingerprinting provided insight into plant metabolism activation/inhibition, taste and trigeminal sensations, and antioxidant properties, not easily attained by other analytical approaches. For example, pu′erh and oolong contained higher relative amounts of amino acids, organic acids, and sugars. Conversely, black tea contained less of all targeted compounds except fructose and glucose, which were more similar to oolong tea. Findings revealed compounds statistically different between spring (pre-monsoon) and summer (monsoon) in pu′erh and oolong teas as well as compounds that exhibited the greatest variability due to seasonal and elevational differences. The UT fingerprinting approach offered unique insights into how differences in growing conditions and commercial processing affect the nutritional benefits and sensory characteristics of tea beverages.

Highlights

Comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC×GC-TOF MS) is considered one of the most informative chemical analysis techniques to characterize complex fractions in food [1,2,3,4]
In this study we explored the information content of the GC×GC-TOF MS data in delineating metabolite signatures capable of capturing the impact of processing and growing conditions in tea
Based on the findings described we found that alanine, aspartic acid, glycine, threonine, valine, phenylalanine, phosphoric acid, xylonic acid, and xylitol were all up-regulated by the plant in the spring compared to summer, monsoon impacted teas

Summary

Introduction

Comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC×GC-TOF MS) is considered one of the most informative chemical analysis techniques to characterize complex fractions in food [1,2,3,4]. Key analytical features of GC×GC include: (a) higher separation power and enhanced resolution realized by combining orthogonal stationary phases for each separation dimension [10]; (b) improved sensitivity, by band focusing-in-space using cryogenic modulation; and (c) ordered/structured separation patterns for homologous series and chemically related organic compounds that aid in peak identification and structural elucidation All of these characteristics make GC×GC-TOFMS the platform of choice to glean the highest level of information content encrypted in compounds/metabolites signatures, while, at the same time, provide reliable and robust results in the challenging domain of food chemical fingerprinting, traceability and origin authentication, technological impact, health, and aroma quality [2,5,11,12,13,14]. Since the fingerprint of multiple samples analyzed by GC×GC-TOF MS can be stacked prior to determining compound identity, compounds present in multiple samples only need to be identified once, which allows for automated peak area (or peak volume) quantitation of that compound in each sample

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