Abstract
(1) Background: beverages based on extracts from Camellia sinensis are popular worldwide. Due to an increasing number of processed teas on the market, there is a need to develop unified classification standards based on chemical analysis. Meanwhile, phytochemical characterizations are mainly performed on tea samples from China (~80%). Hence, data on teas of other provenances is recommended. (2) Methods: in the present investigation, we characterized lyophilised extracts obtained by infusion, maceration and methanolic extraction derived from tea samples from China, Japan, Sri Lanka and Portugal by phytochemistry (catechins, oxyaromatic acids, flavonols, alkaloids and theanine). The real benefits of drinking the tea were analysed based on the bioavailability of the determined phytochemicals. (3) Results: the infusions revealed the highest total phenolic contents (TPC) amounts, while methanolic extracts yielded the lowest. The correlation matrix indicated that the levels of phenolic compounds were similar in the infusions and methanolic samples, while extractions made by maceration were significantly different. The differences could be partially explained by the different amounts of (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG) and gallic acids (GA). The catechin percentages were significantly lower in the macerations, especially the quantity of EGCG decreases by 4- to 5-fold after this process. (4) Conclusions: the results highlight the importance of the processing methodology to obtain “instant tea”; the composition of the extracts obtained with the same methodology is not significantly affected by the provenance of the tea. However, attention should be drawn to the specificities of the Japanese samples (the tea analysed in the present work was of Sencha quality). In contrast, the extraction methodology significantly affects the phytochemical composition, especially concerning the content of polyphenols. As such, our results indicate that instant tea classification based on chemical composition is sensible, but there is a need for a standard extraction methodology, namely concerning the temperature and time of contact of the tea leaves with the extraction solvent.
Highlights
Tea (Camellia sinensis (L.) Kuntze (Theaceae)) is one of the oldest beverages in the world. Pacific Asia is the dominant region for tea drinking, consumption of tea and teabased beverages have been increasing in Europe and in USA
The sum of all the phenolic compounds measured by HPLC-DAD is shown as well as the quantified (−)-epicatechin (EC), (−)-epicatechin gallate (ECG), (−)-epigallocatechin (EGC), (−)-epigallocatechin gallate (EGCG) and (+)-catechin (C). This table contains the amounts of quercetin-3D-galactoside (Q-3-gal), kaempferol−3−glucoside (K), and the oxyaromatic acids 3-Ocaffeoylquinic (o-CQA) and neochlorogenic (5-O-caffeoylquinic) (NCA), and gallic acids (GA)
The levels of catechins, flavonols and oxyaromatic acids obtained for extract samples deriving from different areas were compared by a correlation matrix method, which showed similar compositions of the infusions and methanolic samples, while extractions made by maceration were significantly different
Summary
Tea (Camellia sinensis (L.) Kuntze (Theaceae)) is one of the oldest beverages in the world. Pacific Asia is the dominant region for tea drinking, consumption of tea and teabased beverages have been increasing in Europe and in USA. The global market for tea revenue is about US$ 214,761 million and is expected to grow each year by 6.9% until 2023 Tea is nowadays a drink associated with several health benefits and has been adopted by stressed urban consumers. Consuming green tea prevents lifestyle-related diseases and, reduces morbidity as reported by several studies [1], including cancer [2,3,4,5], and cardiovascular diseases [6,7,8]
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