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本研究选用TN86的不同烟碱转化株系,在相同的栽培、田间管理以及晾制方式下,选取生物碱组成差异明显的烟叶样品进行高温贮藏,测定贮藏前后烟叶TSNAs含量,探究贮藏过程中TSNAs积累及与生物碱含量的关系。结果表明:贮藏前取自90株烟叶的4类生物碱株间差异明显,且以烟碱和降烟碱株间差异最大。控制待测样品总生物碱、NO_3-N和NO_2-N含量相近,45℃高温贮藏12 d后,TSNAs含量远高于贮藏前。与贮藏前相似,NNN和NNK在贮藏期间的增加量分别与其前体物降烟碱和烟碱含量呈极显著正相关。随着降烟碱含量的提高,仲胺类降烟碱形成的NNN增加量显著大于叔胺类烟碱形成的NNK的减少量,使总TSNAs含量增加。相关分析和逐步回归的结果显示,烟碱转化导致降烟碱比例增加是影响高温贮藏后TSNAs形成的主要因素。在烟叶总生物碱、硝态氮和亚硝态氮含量相近的条件下,生物碱组成差异对贮藏过程中TSNAs积累有重要影响。
In this study, different nicotine transformation strains of TN86 were selected. Under the same cultivation, field management and air-curing methods, the tobacco leaves samples with significant difference in alkaloid composition were selected for storage at high temperature. The TSNAs contents of tobacco leaves before and after storage were determined, Accumulation and the relationship with alkaloid content. The results showed that there were significant differences among the four alkaloids extracted from 90 tobacco leaves before storage, and the difference between nicotine and nornicotine was the highest. The contents of total alkaloids, NO3-N and NO2-N in the tested samples were similar, and the contents of TSNAs were much higher than those stored before storage at 45 ℃ for 12 days. Similar to pre-storage, the increase of NNN and NNK during storage was significantly and positively correlated with the nornicotine and nicotine contents of their precursors respectively. With the increase of nornicotine content, the increase of NNN of secondary amine nornicotine was significantly greater than that of NNK formed of tertiary amine nicotine, which increased the total TSNAs content. The results of correlation analysis and stepwise regression showed that the increase of nornicotine ratio was the main factor that affected the formation of TSNAs after high temperature storage. Under the condition of similar content of total alkaloids, nitrate nitrogen and nitrite nitrogen in tobacco leaf, the differences of alkaloid composition had an important influence on the accumulation of TSNAs during storage.