Bull. Spec. CORESTA Congress, Lisbon, 2000, p. 52, AP2
Formation of tobacco specific nitrosamine and population of nitrate-reducing bacteria during the curing stage of Burley tobacco
Japan Tobacco Inc., Leaf Tobacco Research Lab., Oyama, Tochigi, Japan.
The tobacco specific nitrosamine (TSNA) levels of flue- and air-cured tobaccos in Japan were measured. No TSNA was detected in the flue-cured tobaccos we investigated, but TSNA was found in the air-cured tobaccos. We investigated the formation of TSNA and the population of bacteria having the ability to reduce nitrate on Burley tobacco leaves during the curing period, and the influence of the dehydration rates in the browning stage on TSNA formation. TSNA was not detected in lamina until the end of the yellowing stage, while there was an increase in the TSNA level during the browning stage. The population of nitrate-reducing bacteria on lamina was the largest at the end of the yellowing stage, and decreased after that. To investigate the influence of the dehydration rate in the browning stage on TSNA formation, some leaves were, after they turned yellow, hung in a steel pipe chamber covered with vinyl films and sun shading cloth for 2 days to make house-burnt leaves. The TSNA content of house-burnt leaves was higher than that of normal cured leaves at the end of the browning stage. On the house-burnt leaves, the population of nitrate-reducing bacteria increased during the browning stage, became the largest at the end of the stage, and decreased after that.