Carotenoid degradation and derived volatile formation during long-term tea aging.

Carotenoids are important aroma precursors in tea, yet their transformation behavior and sensory contributions during long-term aging remain unclear. In particular, the dynamic degradation patterns of carotenoids and their role in the formation of carotenoid-derived volatile compounds throughout extended tea aging have not been systematically investigated. Here, carotenoid profiles and carotenoid-derived volatiles were systematically investigated in Tieguanyin (TGY) tea aged for 0, 5, 8, and 12 years. Using targeted UHPLC-APCI-MS/MS and HS-SPME/GC-MS analyses, 21 carotenoids and 15 carotenoid-derived volatiles were identified and quantified. Natural aging caused pronounced, time-dependent carotenoid depletion, with more than 99% loss after 12 years. Concurrently, most carotenoid-derived volatiles accumulated progressively, exhibiting high OAVs and strong positive correlations with aging duration. An "in-leaf" thermal degradation model further validated the contribution of carotenoid degradation to volatile formation and revealed distinct degradation behaviors between natural aging and thermal treatment. Natural aging favored the accumulation of upstream cleavage products, whereas thermal treatment induced rapid breakdown and preferential formation of downstream oxidation products, with β-carotene and lutein following different degradation pathways. Collectively, these findings provide mechanistic insight into the origin of carotenoid-derived volatiles in aged tea.