Beyond Pigmentation: The Regulatory Role of Carotenoids in Tea Flavor Formation.

Carotenoids are not only key photosynthetic pigments but also play a key role in shaping the flavor characteristics of tea. Finding out the dynamic changes of carotenoids in tea is of great significance for the precise control of tea quality. Accordingly, this review systematically introduced the biosynthetic pathways and regulatory mechanisms of carotenoids in tea plants and summarized recent advances in rapid detection techniques, particularly spectroscopic methods integrated with computational tools. During the processing of green tea, white tea, yellow tea, oolong tea, black tea, and dark tea, carotenoids underwent complex transformations, including autoxidation, photooxidation, thermal degradation, and enzymatic cleavage catalyzed by carotenoid cleavage dioxygenases (CCDs). Their volatile degradation products, such as β-ionone, α-ionone, linalool, safranal, and β-damascenone, are key volatile compounds that give tea its sweet, floral, and fruity aroma. Oxidative products derived from carotenoids during tea storage also influenced the evolution of tea flavor, increasing the complexity of its sensory characteristics. Overall, volatile carotenoid derivatives were characterized by low odor thresholds and favorable sensory attributes, making them important contributors to tea flavor quality. Tea withering, rolling, fermentation, roasting, drying, and storage are key stages in the degradation of carotenoids and are potential targets for precisely regulating the characteristic flavor of tea.