Formation pathways and thermal-induced transformation of volatile sulfur compounds during black tea processing revealed by integrated GC-IMS and GC×GC-TOFMS.

Volatile sulfur compounds (VSCs) are crucial in defining the distinctive aroma profile of black tea. This study systematically investigated the dynamic evolution and formation mechanisms of VSCs throughout the black tea processing. Nine VSCs were identified and quantified, with polysulfides representing the most abundant category. PLS-DA effectively distinguished different processing stages (R2Y = 0.978 and Q2 = 0.931), with drying identified as a critical phase influencing VSC profiles. OAV assessment revealed that methional (cooked potato-like) and dimethyl sulfide (cooked corn-like) were the predominant aroma contributors, with OAVs consistently exceeding 5000 and 3000, respectively. Methionine-glucose thermal reaction models further demonstrated that both reaction time and temperature critically govern the sequential generation and transformation of key VSCs. A plausible formation pathway was proposed, highlighting methionine as the key precursor and methanethiol as a core intermediate. These findings provide mechanistic insights for the targeted regulation of sulfur-related aroma formation during tea processing.