Real-time fingerprinting of the dynamics of green tea volatiles by ion mobility spectrometry for aroma assessment and discrimination

Abstract

Aroma is a crucial factor determining the tea quality. Tea aroma consists of numerous volatiles and is highly dynamic. Thus, it is significant to generate a comprehensive pattern capturing the dynamic information reflected by the temporal changes of tea volatiles occurring in a relatively short period such as during tea brewing. Herein, a highly time-resolved positive photoionization ion mobility spectrometry (PP-IMS) approach has been developed for real-time fingerprinting of the dynamic changes of tea volatiles. The influences of different ionization sources on the analytical performance were systematically explored. The optimal acquisition time window was determined based on the minimum humidity interference. As a proof of concept, this approach was applied to the assessment and comparison of five different types of green tea aromas. In combination with chemometric tools, five types of aromas were accurately distinguished by using their “dynamic” fingerprints. The RV coefficients (0.20–0.63) and discrimination result showed that the “dynamic” fingerprints contained additional different information on tea volatiles and enabled an improved discrimination of tea aromas, compared to the conventional “static” fingerprints. This study provides a useful tool towards a comprehensive assessment of tea aromas, which is promising to facilitate the quality evaluation and control of tea products.