Effects of black tea extracts on the quality of cigar tobacco leaves during fermentation

Background The quality of cigar tobacco leaves (CTLs) is largely determined by fermentation, yet conventional practices suffer from prolonged duration, limited aroma diversity, and residue accumulation. This study evaluated the effects of four black tea extracts (BTEs)—Pu-erh, Keemun, Dianhong, and Dahongpao—on CTL fermentation and elucidated the underlying mechanisms. Methods Ultra-high-performance liquid chromatography coupled with quadrupole-orbitrap MS/MS (UHPLC-Orbitrap-MS) was used to characterize the chemical composition of BTEs. High-throughput sequencing was performed to analyze shifts in microbial community structure. Volatile aroma compounds (VACs) were detected via headspace solid-phase microextraction combined with gas chromatography–mass spectrometry (HS-SPME-GC-MS), and sensory evaluation was conducted to assess the fermentation effect. Results BTE supplementation significantly restructured the CTL microbial community, increasing Shannon diversity by 20%–40% (TQM: 4.82 ± 0.21 vs. CK: 3.45 ± 0.18, p < 0.05) and enriching potentially beneficial genera such as Sphingomonas while suppressing spoilage-associated Staphylococcus . Moreover, BTEs markedly increased both the diversity and abundance of VACs. Among the four extracts, Dahongpao and Keemun exhibited the most comprehensive sensory improvements (overall quality: 8.6 ± 0.2 and 8.4 ± 0.2 vs. CK: 5.9 ± 0.2, p < 0.05). Correlation network analysis revealed significant associations among BTE constituents (ferulate, theanine, corilagin), specific ASVs (r > 0.8, q < 0.05), and key VACs. Conclusion This study presents a natural strategy for optimizing CTL fermentation, supporting cross-industry integration between the tea and tobacco sectors and providing a technical foundation for producing high-quality cigars.