Changes in content of TSNAs and other compounds of different tobacco types during 6-year long-term storage
Samples of flue-cured, Burley and sun-cured tobaccos from different production areas were collected to investigate the changes in content of tobacco specific nitrosamines (TSNAs) by the SPE-LC-MS/MS method during 6-year long term storage under natural conditions. Alkaloids and nitrate content and other compounds were also measured. Research showed that NNN, NNK, NAB, NAT and total TSNA content of all tested tobacco samples increased continuously throughout the whole storage period following the quadratic curve model. TSNA content of Burley tobacco was the highest and increased most significantly followed by sun-cured tobacco. Alkaloid and nitrate content decreased during storage. The nicotine content of sun-cured tobacco and the nornicotine content of Burley tobacco were the highest, and decreased the most, respectively. Nitrate content of different tobacco types varied greatly within the tobacco types, with Burley tobacco being 109.7 times higher than that of flue-cured tobacco. Volatile ketones, the important aromatic compounds, changed differently with tobacco types and compounds, although all could be fitted into a quadratic curve model. Total amino acid and aspartic acid content in Burley tobacco were the highest, followed by sun-cured tobacco. Flue-cured tobacco had the lowest total amino acid content, although the proline content was the most abundant.