Impact of Six Typical Processing Methods on the Chemical Composition of Tea Leaves Using a Single Camellia sinensis Cultivar, Longjing 43

While the Camellia sinensis cultivar and processing method are key factors that affect tea flavor and aroma, the chemical changes in nonvolatile components associated with the tea processing method using a single cultivar of C. sinensis have not been reported. Fresh leaves from C. sinensis Longjing 43 were subjected to six tea processing methods and evaluated by targeted and untargeted chromatographic procedures. On the basis of targeted assessment of the total catechin content, three clusters were identified: yellow–green, oolong–white–dark, and black. However, principal component analysis of the total tea metabolome identified four chemical phenotypes: green–yellow, oolong, black–white, and dark. Differences in the non-catechin components included amino acids and γ-aminobutyric acid, which increased in white tea, and dihydroxyphenylalanine, valine, betaine, and theophylline, which increased in dark tea. Overall, this study identified a wide range of chemicals that are affected by commonly used tea processing methods and potentially affect the bioactivity of various tea types.