不同初烤烟叶叶片和烟梗TSNAs含量及高温贮藏后的变化研究

为明确不同地区、不同品种、不同部位初烤烟叶叶片和烟梗TSNAs含量及其与前体物之间的关系，探明高温贮藏对TSNAs形成的影响。收集了我国河南、云贵、粤湘产区的30个烤烟初烤后烟叶样品，在河南洛阳设置品种试验，另将初烤叶片和烟梗进行高温贮藏，研究烟草特有亚硝胺、生物碱和硝酸盐含量的变化。结果表明，初烤烟叶叶片TSNAs含量均显著高于烟梗，且在叶片中NNN比例较高，在烟梗中则以NNK比例较高；叶片中生物碱总量约为烟梗的4.7倍；硝酸盐含量则表现为烟梗中含量远高于叶片。不同地区叶片TSNAs含量达到极显著差异，以湘粤产区含量最高；不同品种叶片的TSNAs含量达到显著差异，生物碱含量较低的品种TSNAs含量较低；各部位烟叶TSNAs含量均表现为叶片 > 支脉 > 主脉。相关分析表明在烟叶烘烤过程中烟叶生物碱含量对TSNAs积累的影响较大。经高温贮藏后叶片和烟梗TSNAs含量增加幅度有较大差异，其中烟梗TSNAs增加比例达到229.2%，叶片增加30.6%，硝酸盐含量对高温贮藏过程中TSNAs形成影响较大。 

TSNAs contents in lamina and midrib of flue-cured tobacco and their changes after high temperature storage

Thirty flue-cured tobacco samples from Henan, Yunnan, Guizhou, Hunan and Guangdong were collected and a variety test was set up in Luoyang, Henan province to investigate the relationship between TSNAs content and their precursors in flue-cured tobacco lamina and midrib, and effect of geographic location, variety and leaf position on this relationship. Flue-cured tobacco lamina and midrib were stored at 50℃ to study the effect of high temperature storage on contents of TSNAs, alkaloid and nitrate. Results showed that content of TSNAs in flue-cured tobacco lamina was significantly higher than in midrib, and the highest proportion in lamina was NNN, whereas the highest percentage in midrib was NNK. Total alkaloids in lamina were about 4.7 times higher than in midrib. Nitrate content in midrib was higher than in lamina. TSNAs content in lamina varies significantly between regions, with the highest content in Hunan and Guangdong. Significant differences were found in TSNAs content of lamina between varieties, and the changes of TSNAs were closely related with alkaloid content. Lamina had the highest TSNAs content, followed by side-vein and mid-vein. Correlation analysis revealed that accumulation of TSNAs in tobacco was mainly affected by amount of alkaloid accumulated during flue-curing. TSNAs content of midrib and lamina under 50℃ storage increased 229.2% and 30.6%, respectively, compared with that in low temperature, suggesting that nitrate levels had greater influence on TSNAs formation during high temperature storage.