Abstract
Tea is one of the most consumed beverages in the world and its quality is influenced by geographical origin and production methods. This study focuses on the volatile aroma components of 38 tea products from China, Japan, Indonesia, Sri-Lanka, and Chinese Taipei; among them 7 green teas, 13 oolong teas, and 18 black teas. The volatiles were extracted from the infusions using PorapakQ-resin, concentrated, and analyzed by gas chromatography-mass spectrometry. The components were identified by authentic reference compounds or preliminary based on their mass spectra. Different manufacturing processes yield different blends of aroma compounds. In general, the contents of total volatiles, aliphatics, aromatics, and terpenoids increased with the fermentation degree, whereas jasmine lactone and indole were the highest in oolong teas. Some particular manufacturing processes, for example, the use of tea leaves infested by the tea green leafhopper, lead to higher contents of volatiles in final products as in Oriental Beauty oolong tea. The relative peak areas determined for 82 volatiles were the basis for the statistical analysis and highlight the potential of multivariate analysis to distinguish tea samples of different categories.
Highlights
Tea (Camellia sinensis) is a plant commercially grown for beverage production
The aroma compounds of tea such as green tea, oolong tea and black tea have been individually investigated by gas chromatography-mass spectrometry (GC-MS) or GC-olfactometry (GC-O) [3]-[7]
In this study we compared the volatile profiles of green teas, oolong teas, and black teas using equal extraction conditions for all samples
Summary
Tea (Camellia sinensis) is a plant commercially grown for beverage production. Teas are classified based on the manufacturing process and can be divided up into six major families, including non-fermented green tea, slightly fermented white tea, semi-fermented oolong tea, fully fermented black tea, post fermented yellow tea, and dark (red) tea (Figure 1). Yellow tea, and dark tea are characteristic Chinese teas and popular in China, whereas green tea, oolong tea, and black tea are well-known all around the world and in particular focus of this study. Formation of tea aroma is influenced by different manufacturing processes. The particular manufacturing process of oolong tea gives a unique floral, fruity, and jasmine-like aroma [1] [2]. In addition various approaches were employed for the discrimination of teas from different geographical origins such as high performance liquid chromatography [8], capillary electrophoresis [9] or electronic nose [10]
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