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【Objective】The use of artificial inoculation to ferment cigar tobacco leaves is an inevitable trend in the industrial production of cigar tobacco leaves, and the neutral aroma components are the important quality components of cigar tobacco leaves. The study aims to investigate the effect of Bacillus safensis GL2 on the neutral aroma components of cigar tobacco leaves.【Method】GL2 was screened from Cuban cigar Cohiba Robert and used to ferment cigar leaves. The neutral aroma components in tobacco leaves were determined by distillation extraction-gas chromatography-mass spectrometry, and multivariate statistical methods were used for analysis and statistics.【Result】The total aroma and the contents of most neutral aroma components in cigar tobacco leaves were significantly increased after GL2 fermentation (P < 0.05), and the increased aroma substances mainly included olefins, ketones and alcohols. A total of 13 differentially neutral aroma components were selected by VIP > 1 and P < 0.05, and 9 of them were significantly up-regulated and positively correlated with tobacco leaf aroma. There were 7 species with significant positive correlation (P < 0.05), which were the key differential aroma components of 2, 6, 6-trimethyl-2-cyclohexene-1, 4-dione, 2, 6, 6-trimethyl-1, 4-cyclohexanedione, geraniyl acetone, acanthyl acetone, neophydiene, solanone and phytoalcohol. In addition, 4 different aroma components were significantly decreased and negatively correlated with tobacco leaf aroma, among which 2, 4-di-tert-butyl-6-nitrophenol was significantly negatively correlated with cigar tobacco aroma (P < 0.05). 2, 6, 6-trimethyl-2-cyclohexene-1, 4-dione, geranyl acetone, solanone and phytol contributed significantly to the aroma of fermented cigar tobacco leaves, resulting in a stronger overall dry and floral fragrances. As a result, they enriched the aroma and improved the sensory quality of cigar tobacco leaves.【Conclusion】Inoculation of B. safensis during cigar tobacco fermentation is beneficial for improving the quality of cigar tobacco leaves, which provide theoretical support for improving the fermentation quality of cigar tobacco leaves with biotechnology.

【Objective】Microorganisms play a key role in the fermentation process of cigar tobacco leaves. In order to better improve the quality of cigar tobacco leaves, it is necessary to screen the dominant strains of cigars and apply them to the fermentation of cigar tobacco leaves. Therefore, it is necessary to optimize and expand the biomass of the dominant strains.【Method】16S sequencing and physiological and biochemical analysis were carried out on a dominant strain ZLX10 screened from cigars to identify the strain. At the same time, the composition of culture medium (carbon source, nitrogen source and inorganic salt) and culture conditions (inoculation amount, liquid content and seed age) were optimized through single factor and orthogonal test to improve its biomass.【Result】Based on 16S rDNA sequence comparison, the sequence homology between strain ZLX10 and Bacillus mojavensis (MT043920.1) reached 99.86%, and the strain had strong ability to degrade polysaccharide and protein macromolecule, which could be identified as Bacillus mojavenis. Through single factor and orthogonal test, the optimal medium formula of strain ZLX10 was obtained as follows: carbon source (sucrose) 50 g/L, nitrogen source (yeast extract) 20 g/L, inorganic salt (MgSO4) 0.25 g/L, and the optimal culture conditions were 1% (V/V) of inoculum, 30 mL/250 mL of liquid content, and 24 h of seed age. The biomass of strain ZLX10 was 1.98 times that before optimization when cultured under the optimal conditions for 24 h.【Conclusion】The biomass of strain ZLX10 can be significantly increased by optimizing the conditions, which provides a basis for artificial inoculation of fermented cigar tobacco leaves.

【Objective】At present, the effect of deep fermentation on the quality of cigar tobacco leaves is still unclear, and volatile components are important factors affecting the sensory quality of cigars. The study is carried out to explore the changes of volatile components during the deep fermentation of wrappers and to analyze the effects of deep fermentation on the quality of cigar tobacco leaves.【Method】HS-SPME/GC-MS method was used to analyze the volatile components of samples in five stages of deep fermentation of cigar wrappers in industrial production.【Result】37 volatile components were identified from wrapper samples, mainly including nitrogen-containing compounds and alcohols, followed by esters and ketones. In terms of relative content, nicotine and neophytadiene were the main components. The relative content of volatile nicotine was the highest, accounting for 76.28% -83.32% of the total volatile matter, and that of neophytadiene accounted for 11.60% -15.88% of the total volatile matter, followed by nitrogen-containing compounds (except for nicotine) and ketones, and the volatiles showed a significant upward trend as a whole. 13 main differential volatile compounds were screened out from the wrappers, mainly including hexahydro pseudoviolone, geranyl acetone, β-ionone, phytone, farnesyl acetone, 3-acetylpyridine, 1-acetylpyrrolidine, mesamine, nicotyrine, and 2, 3'-bipyridine, etc.【Conclusion】Deep fermentation has no obvious effect on the types of volatiles in wrappers, but it has a significant effect on their contents. This will provide a basis for improving the quality of cigar wrappers.