Unraveling the dynamic metabolite changes during the rolling–cutting of CTC black tea at an industrial scale

BACKGROUND The rolling–cutting process (RCP) is a crucial process in crush–tear–curl (CTC) black tea, but its quality formation is far from clear. This study aims to elucidate the dynamics of sensory quality and metabolites through quantitative descriptive analysis, headspace solid-phase microextraction/gas chromatography–mass spectrometry, and liquid chromatography–tandem mass spectrometry. RESULTS Sixteen key characteristic aromas with ratio of each relative odor activity value (rOAV) to the maximum rOAV (ROAV) ≥ 0.1, variable importance in projection (VIP) > 1, and P < 0.05 were screened out, and linalool, (2 E )-2-nonenal, and ( E )-2-hexenal were the top three ROAVs. The RCP mainly facilitated the release of grassy aromas through fatty acid oxidation while also promoting the synthesis of fruity aromas through monoterpene biosynthesis and phenylpropanoid/benzoid biosynthesis. Additionally, 72 non-volatiles (VIP > 1.50, P < 0.01) were identified as characteristic metabolites, and flavonoids accounted for the largest proportion. RCP accelerated the glycosylation of kaempferol and quercetin to enhance the bitter and astringent attributes. CONCLUSION These findings will promote the comprehension of CTC black tea quality formation in RCP. © 2025 Society of Chemical Industry.