烟叶生物碱组成差异对白肋烟高温贮藏前后TSNAs形成的影响

摘要

Field experiment was set up to select tobacco samples with different alkaloid composition by choosing different nicotine conversion strains of TN86 under the same fi eld management and air-curing conditions. The selected samples were stored in temperature/humidity-controlled chamber at 45℃ for 12 d to explore the source of TSNAs accumulation during high temperature storage and its relationship with alkaloid content. Results showed that signifi cant variation of individual alkaloids existed among 90 tobacco plants with greatest diff erences being observed for nicotine and nornicotine contents. With approximately same levels of total alkaloids, NO3-N and NO2-N contents, TSNAs contents at 45℃ for 12 d were signifi cantly higher than those before storage. The increase of NNN and NNK contents during storage was significantly positively correlated with their precursors, nicotine and nornicotine, respectively. With the increase of nornicotine content, the net increase of NNN from nornicotine nitrosation during storage was greater than the net decrease of NNK from nicotine nitrosation, leading to the net increase of total TSNAs content. Results of correlation and stepwise regression analysis showed that the increased percentage of nornicotine caused by nicotine conversion, was the main factor infl uencing TSNAs formation during high temperature storage. It could be concluded that at same levels of total alkaloid, NO3-N and NO2-N content of tobacco leaves, the diff erence in alkaloid composition has signifi cant impact on TSNAs formation and accumulation during leaf storage.%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、NO3-N和NO2-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.