Rapid volatiles fingerprinting by dopant-assisted positive photoionization ion mobility spectrometry for discrimination and characterization of Green Tea aromas.

Aroma is one major concern of tea flavor and represents an essential criterion for quality evaluation. Herein, we presented a novel approach for rapid, non-destructive and real-time fingerprinting of green tea aromas using ion mobility spectrometry (IMS) without prior sample treatment. Positive photoionization with acetone as dopant was selected as suitable source for tea volatiles analysis in comparison to other sources. To demonstrate the effectiveness of presented method, chestnut-like aroma, an indicator of high-quality green teas, was distinguished from others using IMS fingerprinting. In particular, three sub-types with subtle difference in sensory evaluation, i.e., tender, pure and roasted chestnut-like aroma, were classified by IMS fingerprinting in combination with chemometrics with an overall predictive accuracy of 95.6%. Furthermore, we demonstrated a strategy of two-dimensional IMS profiling for capturing the "dynamics" of tea volatiles. To our knowledge this is the first report of tea aroma analysis using IMS-based tool, which may serve as a complement to the conventional tea sensory evaluation and is promising for process monitoring during tea manufacture.