Gc In Different Tea Quality Identification Applications

Tea tree is an evergreen shrub whose leaves are used to produce tea through processing. Tea quality varied widely according to type of tea and geographical origin et al. Semi-oxidised oolong tea is called blue-green tea, which is one of the six main types of Chinese teas. Major Oolong tea growing regions are Fujian, Taiwan, and Guangdong provinces. Anxi Tieguanyin is one of the best brands of the Oolong teas. In this thesis, Anxi Tieguanyin teas were investigate based on GC-MS non-targeted profiling method. The main results were as follows:A GC-MS metabolomics method for tea analysis was established. Sample pretreatment method was developed. Extraction solvent and derivatization conditions were investigated and optimized. The optimal extraction solvent was 70% methanol solution. Validation of the method was carried out. Repeatability, recovery and linearity results showed that the developed method could meet the analytical requirement. Using the developed method, a typical Tieguanyin was analyzed. A total of 69 metabolites were tentatively identified, including 7 sugars,14 amino acids,20 organic acids.Then, Tieguanyin and three main Oolong tea varieties (Benshan, Mao Xie and Huang Jin Gui) originated from eight towns within Anxi country were analyzed using the developed method. The PCA score plot showed that the phenotype of Oolong tea from different towns varied widely. Tieguanyin from geographically adjacent regions were clustered.Finally, four main types of tea including green tea, white tea, Oolong tea (Tieguanyin and Shui Xian) and the black tea were investigated. The PCA score plot indicated obvious discrimination of teas according to their degrees of fermentation. Tieguanyin and Shui Xian belong to the Oolong tea, and they are clustered nearby on PCA score plot. The phenotype of black tea have the biggest difference from other types of tea.