TEA (CAMELLIA SINENSIS L.) VOLATILES PROFILING BY HEADSPACE - TWODIMENSIONAL COMPREHENSIVE GAS CHROMATOGRAPHY - MASS SPECTROMETRY: FLAVOR COMPOUNDS QUANTIFICATION CHALLENGES

Tea infusions are the most consumed beverages around the world, prepared by water infusion of dried leaves from Camellia sinensis and consumption is associated with several health benefits. Teas are classified into three major categories: unfermented green teas, semifermented oolong teas, and fully-fermented black teas, with the latter accounting approximately 80% of the total world tea production [1]. The sensory quality of tea is undoubtedly a key-factor affecting consumer preference, it includes color, strength, taste and aroma [1]. While phenolic compounds (mainly glycosides) and xantines conditions tea color and taste, volatile compounds are fundamental for its aroma. More than 600 volatiles have been identified in fully fermented black tea, and 41 of them have been identified as key contributors to the black tea aroma [2]. Green tea, on the other hand, is characterized by a less complex volatile fraction of about 200 volatiles, 30 of them contributing to its distinctive aroma [3]. This study reports the results of a systematic investigation on the effectiveness of different sampling approaches by miniaturized extraction devices, based on either sorption and adsorption polymers, hyphenated with a twodimensional comprehensive gas chromatography mass spectrometry analytical platform. A selection of different high concentration capacity (HCC) sample preparation devices for Solid Phase Microextraction (SPME), Stir Bar Sorptive Extraction (SBSE) and Headspace Sorptive Extraction (HSSE) together with Dynamic Headspace (D-HS) techniques have been investigated to provide information useful for fingerprinting of tea dried leaves and resulting infusions. In the present study, volatiles and semi-volatiles contributing to define fermented and green teas aroma have been successfully characterized thanks to the combination of effective and selective sampling by HCC and D-HS techniques, high separation and detection power of GC×GC-MS and suitable data elaboration (i.e., Comprehensive Template Matching Fingerprinting- CTMF) [4]. Within the sample preparation techniques investigated, HSSE and SBSE have shown to be really effective for tea quantitative profiling because of both their high concentration factors and highly representative profiles, which cover most of the highly sensory informative chemicals contributing to the final aroma perception. References [1] Z. Yang et al., Food Res. Int. 53 (2013) 585. [2] C. Schuh et al., J. Agric. Food Chem. 54 (2006) 916. [3] K. Kumazawa et al., J. Agric. Food Chem. 47 (1999) 5169. [4] C. Cordero et al., J. Chromatogr. A 1318 (2013) 1.