Comparative analysis on chemical characteristics of different grades CTC black tea

The different grades CTC (Crushing, tearing and curling) black tea as materials, those, sensory quality, chemical compositions and volatile flavor compounds (VFC) were measured to invest the chemical characteristics for the improvement of processing technology and quality. There were no significant differences in free amino acids and soluble sugars (p<0.05) between three grades CTC black tea. While caffeine contends increased significantly (p<0.05), tea polyphenols just decreased significantly (p<0.05). Catechins showed a downward trend. Theaflavins (TF), thearubigins (TR) and theabrownins (TB) contends increased in CTC black tea. The ratio of TR and TB could reflect its soup color observed. VFC originated from farnesyl diphosphate or granyl geranyl pyrophosphate degradation were the major VFC in black tea. So, tea polyphenols, caffeine and TR were the main reasons to regulate the quality of different grades CTC black tea, while the main VFC had not changed.