Abstract: In order to explore the best conditions of mixed microbial solid⁃state fermentation of low⁃grade tobacco leaves，this study investigated the effects of single and mixed microbial fermentation on volatile aroma components of tobacco leaves.Two flavour⁃producing yeast strains（YJX，MG）were used as test strains.The optimal fermentation conditions of tobacco leaves were determined by single factor experiment and orthogonal optimization experiment with the content of volatile aroma components as evaluation indicator.The volatile aroma components of tobacco leaves without microbial fermentation and fermented tobacco leaves were analyzed by simultaneous distillation extraction and gas chromatography⁃mass spectrometry（GC/MS）.The improvement of the quality of the low⁃grade tobacco leaves after fermentation under the optimum fermentation conditions was studied. The results showed that the optimum fermentation conditions were fermentation temperature of 30℃，mixed microbial ratio（YJX∶MG）of 2∶1，inoculation amount of 25% and fermentation time of 24 h.The primary and secondary factors affecting the content of aroma substances in the fermentation process were mixed microbial ratio>inoculation amount>fermentation temperature. GC/MS analysis showed that 95 volatile aroma components were detected，including 12 alcohols，21 carbonyls，8 acids，15 esters and lactones，23 hydrocarbons，10 heterocycles and 6 phenols.The content of volatile aroma components in tobacco leaves fermented by mixed microbes was significantly higher than that of tobacco leaves fermented by single microbe and without microbes.Mixed fermentation could increase the volatile aroma components of tobacco leaves，improve the aroma quality and quantity，and significantly improve the quality of tobacco leaves.

Key words: Low?grade tobacco leaf, Mixed microbes, Solid?state fermentation, Aromatic ingredients, Orthogonal optimization

摘要： 为探究混菌固态发酵低次烟叶的最佳条件，考察单菌发酵和混菌发酵对烟叶挥发性致香成分的影响。以2株产香酵母（YJX、MG）为试验菌株，通过单因素试验和正交优化试验，以挥发性致香成分含量为评价指标，确定烟叶最佳发酵条件，利用同时蒸馏萃取和气相色谱/质谱（GC/MS）联用的方法对未经微生物发酵的烟叶及发酵烟叶的挥发性致香成分进行分析，通过评吸明确混菌固态发酵对烟叶感官品质的提升水平。结果表明，最佳发酵条件为发酵温度30 ℃、混菌比（YJX∶MG）2∶1、接种量25%、发酵时间24 h，发酵过程中致香物质含量影响因素的主次为混菌比>接种量>发酵温度。运用GC/MS对单菌及混菌发酵获得的挥发性致香成分含量进行分析，共检测出95种挥发性致香成分，包含12种醇类、21种羰基类、8种酸类、15种酯类和内酯类、23种烃类、10种杂环类和6种酚类化合物，混菌发酵烟叶中的挥发性致香成分含量明显高于单菌发酵和未添加微生物发酵烟叶。混菌发酵能够增加烟叶的挥发性致香成分含量，香气质和香气量得到提升，烟叶品质明显改善。

关键词: 低次烟叶, 混菌, 固态发酵, 致香成分, 正交优化