Volatile profile characterization during the drying process of black tea by integrated volatolomics analysis

Drying plays an important role in the development of high-quality aroma black tea. In this study, changes in the volatile profiles of Congou black tea samples subjected to different drying times were comprehensively char-acterized via gas chromatography-electronic nose, gas chromatography-mass spectroscopy, and gas chromatography-ion mobility spectroscopy (GC-IMS) analyses. Different drying times generated different aroma types (e.g., floral and sweet aromas, etc.). Forty-five minutes of drying treatment was identified as a critical time point for the formation of tea aroma quality, since at this point additional drying caused a decline in aroma quality. Here we identified a total of 90 volatile organic compounds, mainly alcohols and aldehydes, using GC-IMS. Based on the volatile fingerprints generated by GC-IMS, an authentic orthogonal partial least squares discriminant analysis model with credible parameters ((RY)-Y-2 = 0.921, Q(2) = 0.817) was established. Moreover, using variable importance in projection > 1.35 and p < 0.05 as filtering criteria, six variables including four identified key differential components were screened out. This study provides a new perspective for under-standing the dynamic changes occurring during drying and lays a theoretical foundation for precise and quality -oriented processing of Congou black tea.