Effect of storage environment on nitrogen oxides formation in cured tobacco leaves
Experiments were carried out to elucidate the mechanisms of TSNA formation during storage by confirming the participation of nitrogen oxides (NOx) produced from tobacco leaves under high temperature. The contents of NOx in an airtight environment set up by a vacuum desiccator were detected for different tobacco types, storage temperatures and duration, and moisture contents of tobacco. Results showed that NO as the main component accounted for more than 90 % of the NOx volatilized from tobacco leaves during storage. The NOx concentration produced from Burley tobacco leaves was almost nine times higher than that from flue-cured tobacco samples under the same storage conditions. When storage temperature increased from 10 °C to 50 °C, the concentration of NO and NO2 volatilized from Burley tobacco increased gradually after treating for 48 h, and significant differences were observed between the five temperature treatments. NOx was produced from Burley tobacco samples in a short period of time (2 h) under 50 °C, and the volatilisation of NOx increased as the storage time increased. Under the same storage temperature, the NO and NOx concentrations of tobacco leaves with moisture content higher than 18 % were significantly lower than the samples with moisture content of 11 % and 12 %. Presence of activated carbon in the tobacco storage containers effectively reduced the concentration of NOx. Collectively, proper control of the storage environment is an effective way to reduce TSNA formation in stored tobacco leaves by inhibiting and reducing the production of NOx from tobacco itself.