Analysis of aroma differences in upper low-grade tobacco leaves pre-and post-bacterial-enzyme synergistic fermentation

SU Zan; CAO Yuan; SUN Jiansheng; HU Zhizhong; ZOU Kexing; LIU Hong; LONG Zhangde; XU Chunping

doi:10.12187/2025.06.008

Abstract：[Objective]To investigate differences in aroma components of tobacco leaves before and after bacterial-enzyme synergistic treatment.[Methods]A strain of Bacillus velezensis YUNM-4,isolated from the surface of Yunyan 87 tobacco leaves,was combined with cellulase,lipase,and neutral protease to formulate a composite enzyme preparation.This preparation was applied in synergistic fermentation of upper low-grade flue-cured tobacco leaves.Conventional chemical components and aroma components of fermented tobacco leaves were analyzed using a continuous flow analyzer and gas chromatography-mass spectrometry(GC-MS),respectively.Orthogonal partial least squares discriminant analysis(OPLS-DA)and independent t-tests(P<0.05)were employed to identify components with significant content differences between pre-and post-fermentation samples,while relative odor activity values(ROAV)were applied to analyze differences in aroma component contributions.[Results]1)Compared to the control group,fermented tobacco leaves exhibited significant decreases in total potassium,nicotine,total sugar,reducing sugar,and K/Cl ratio,while the sugar/nicotine ratio increased significantly.2)The total content of volatile aroma components in post-fermentation samples increased significantly to 498.09 μg/g,representing a 53.66%increase,primarily due to alcohols,ketones,hydrocarbons,organic acids,furans,and phenols.The OPLS-DA model demonstrated excellent reproducibility and no overfitting,as confirmed by cross-validation,identifying 32 components with significant content differences that effectively distinguished pre-and post-fermentation aroma profiles.3)Twelve volatile aroma components in post-fermentation samples showed higher ROAV values than pre-fermentation samples,with 11 components(including benzyl alcohol,phenylethyl alcohol,damascenone,β-ionone,acetophenone,and dihydroactinidiolide)having ROAV>1,indicating their role as key aroma components.[Conclusion]Treatment of upper low-grade flue-cured tobacco leaves with bacterial-enzyme synergistic fermentation significantly improves cigarette sensory quality.