Abstract: In order to improve the availability of low-grade tobacco leaves and prepare tobacco flavors, low-grade tobacco leaves were used as raw materials, and the aroma-producing microorganism Bacillus velezensis CF-14 was used as the fermentation strain to apply to the tobacco extract. The fermentation conditions of the extract were optimized by a single factor experiment, and the volatile components of the extract before and after fermentation were analyzed by GC-MS. The tobacco extract under the optimal fermentation conditions was used for cigarette smoking evaluation. The results showed that: ①The preferred medium was 1% soluble starch, 1% yeast powder and 1% potassium chloride. The fermentation conditions of seed liquid were as follows: inoculation amount 1%, initial pH 6.00, liquid filling volume of 60 mL, temperature of 28 ℃. The fermentation conditions of the extract were as follows: fermentation time 24 h, inoculation amount 1%, fermentation temperature 32 ℃. ②The results of the electronic nose showed that the response value of the fermented extract on each sensor was higher than that of the unfermented extract, and the alcohols and ketones increased significantly.③The results of GC-MS showed that two significantly different clusters were formed before and after fermentation. There were 48 and 61 volatile components in the tobacco extract before and after fermentation, and the total volatile components were 386.69 and 498.39 μg/g, respectively. The contents of ketones and alcohols in the extract after fermentation were significantly higher than those before fermentation, and the contents of phenols, acids and aldehydes increased. ④After the extract under the optimal fermentation conditions was applied to cigarettes, the aroma quality of cigarettes was improved, the amount of aroma increased, the miscellaneous gases and irritation were reduced, the harmony was better, the sweetness was increased, and the smoking quality of cigarettes was better.

Key words: Bacillus velezensis, tobacco, fermentation, flavor, sensory evaluation