Floral extracts as fermentation modulators: improvement of cigar tobacco quality via microbial and chemical reshaping

The quality of cigar tobacco leaves relies heavily on fermentation optimization. Media fermentation enhances this process through exogenous functional extracts, offering targeted improvement in leaf quality. While various plant extracts have been explored, floral extracts remain underexamined despite their rich aromatic profiles and potential to regulate microbial activity. This study investigated the effects of four floral extracts (Prunus mume, Jasminum grandiflorum, Osmanthus fragrans, and Eriobotrya japonica flower) as fermentation media on the chemical, microbial, and sensory properties of cigar tobacco leaves. Chemical characterization revealed that the four floral extracts possessed distinct phenolic profiles, characterized by varying compositions of flavonoids, phenolic acids, and glycosides. As fermentation media, all four floral extracts significantly reduced total nitrogen (by up to 6.63%) and alkaloid content (by up to 9.97%), while increasing sugar levels, with Osmanthus fragrans extract showing the most pronounced effect (62.11% higher reducing sugar content). The extracts also promoted the accumulation of key aroma compounds, including neophytadiene and megastigmatrienones, with the Prunus mume group achieving 32.47% increase in total aroma content. Microbial analysis showed selective enrichment of aroma-synthesis-linked taxa, including Pseudomonas, Enterobacter, Aspergillus, and Wallemia, which strongly correlated with multiple aroma components. Sensory evaluation confirmed targeted improvements: Prunus mume extract enhanced aroma smoothness and richness, Jasminum grandiflorum extract notably improved sweetness and fluentness, Osmanthus fragrans extract effectively increased mellowness and cleanliness, while Eriobotrya japonica flower extract performed best in aftertaste. This study demonstrates that floral extracts can act as reliable precision fermentation media by shaping microbial communities and driving desirable chemical transformations. The results provide a mechanistic basis for using floral resources to improve cigar tobacco quality and introduce a targeted, function-driven framework for developing next-generation fermentation additives.