Key aromatic compounds in Tieguanyin oolong tea shoots: Processing changes in different portions

The dynamic changes of characteristic volatiles in different portions of tea shoots were profiled to depict their contributions to the aroma development of Tieguanyin tea in this study. As a result, 392 volatile organic compounds (VOCs) were identified and quantified, of which Indole, Linalool, Methyl salicylate, α-Farnesene were regarded as biomarkers. Methyl salicylate, β-myrcene, indole, hexanal and 5-trimethyl-5-ethenyltetrahydro-2-furanmethanol were dominant in stem part, whereas nonanal and linalool exclusively contributed to the floral scent of leaf samples. Further analyses on OAV contributions indicated that floral-fruity VOCs demonstrated similar dynamic variations in both stem and leaf portions throughout the production process, with the maximum contents observed during withering or turning-over steps. The reduction in both floral-fruity and green-grassy odors were caused by the thermal effect at drying step, contributing to the convergence of aroma components and the formation of unified flavor in tea. • Nonanal and Linalool exclusively contributed to floral scent of leaf portion. • A quality convergence between leaf and stem was induced by thermal effect. • The merged aroma between stem and leaf enhanced the characteristic flavor. • Manufacturing operations retained the floral, while reducing the grassy VOCs.