¹H NMR Spectroscopy on Composition of Water Extract from Tie-guanyin Teas

Nuclear magnetic resonance spectroscopy was applied to obtain metabolic fingerprints of the water extracts of Tie guanyin teas. By using the multivariate statistical analysis on the data obtained on the extracts from consecutive steeping, the compositional differences between the lightly and strongly fragrant varieties of the tea were compared. Overall, the concentrations of the elements in the extracts decreased with increasing number of steeping. On the 5^th tea brewing, the concentrations became less than 10% of the initial amount, which invariably changed the sensory quality of the tea. There were significant differences in the chemical make ups between the lightly and strongly fragrant varieties of the tea. The strongly fragrant variety tended to have a significantly higher contents of sucrose and epicatechin, but lower of theanine, epicatechingallate, quinate, isoleucine, and epigallocatechin/epigallocatechingallate than its lightly fragrant counterpart.