Dynamic Change of Carotenoid Compounds during Congou Black Tea Manufacturing Process

In this paper, the composition and content of carotenoids in fresh tea leaves and intermediate products of Congou black tea manufacturing were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the dynamic changes of different types of carotenoids during the manufacturing process were analyzed. Results showed that a total of 24 carotenoids were detected in all studied samples, including 3 carotenes, 10 lutein and 11 carotenoid esters. The contents of different types of carotenoids greatly differed, with the predominant ones being lutein, (126.0000 ± 3.6056)–(317.6667 ± 12.6623) μg/g, and β-carotene, (31.5333 ± 1.3650)–(70.1667 ± 1.6503) μg/g. The contents of some carotenoids components varied greatly during tea processing, and the variation coefficient of lutein palmitate content was the largest (130.85%) among them. Meanwhile, the contents of different carotenoids showed three overall trends, and the rates of change in lutein at the fermentation and drying stages were the largest, which were 10.25 and 58.33 μg/(g·h), respectively. In addition, continuous moderate temperature, enzymatic oxidation and intense moisture-heat conditions were found to be the major triggers for changes in carotenoid contents, but they had different impacts on different carotenoids. The results of this study will provide an important scientific basis for the formation of black tea flavor quality.