Chemical constituents analysis of white tea of different qualities and different storage times

Gallic acid, caffeine, catechins and amino acids in different grades of white teas and white teas under different storage times were determined in this study. The qualitative analysis was carried out on the main chemical components in white teas by ultra-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UPLC-QQQ-MS/MS). A total of 29 compounds were detected in white teas. The results showed that contents of total catechins and caffeine decreased with grades reducing. The middle-grade of white tea, Gong Mei, contained the amino acids at the highest content of 53.606 mg g(-1), while the low grade Shou Mei contained the lowest (14.848 mg g(-1)). It was observed that contents of catechins and amino acids showed a similar tendency to decrease with storage times, while gallic acid increased with storing time (from 0.770 to 1.420 mM). This study suggested that high- and low-grade white tea should not be distinguished solely based on a single characteristic component or by market price, as well as providing an important basis for changes in characteristic components in white tea of different storage times.