CORESTA Congress, Shanghai, 2008, AP 08

The influence of post-curing handling of Burley and dark air-cured tobacco on TSNA and nitrite levels

Institut du Tabac, Imperial Tobacco Group, Bergerac, France
While most of Tobacco Specific Nitrosamines (TSNA) are formed during air-curing, further accumulation may occur between end of cure (EOC) and delivery. In order to investigate putative factors affecting this accumulation, different ways of storing have been simulated. Burley or dark air-cured tobaccos were grown and stalk cured according to standard practices at Bergerac (France). Midribs and lamina were analyzed for TSNA, nitrites, nitrates, and alkaloids, immediately after EOC and after conservation. In 2005 and 2006, the following conservation means were compared using middle leaves of Burley cultivars:· A and C: conservation in the curing plastic shed, either in bales (A) or stacked leaves (C).· B: Delayed taking down: plants were left hanging in a part of the same shed,· D: Immediate threshing after EOC, then conservation in boxes at ambient temperature. Additionally, cutters and tips from A, C and D plants were baled immediately after EOC at different pressures (standard, and standard minus 50%) and moistures (standard: 22% - tips, 18% - cutters, and low: 15%), and kept for 3 months in the shed. In 2007, one Burley and one dark air-cured cultivar were stalk cured in a plastic shed. Immediately after EOC, bales from each of the three leaf levels and cultivars were made at standard pressure and moisture, and stored for 3 months, either at ambient temperature (shed), at 4 °C (cold chamber), or at 30 °C (climatic room). The only significant increase in TSNA accumulation was observed in the delayed taking down treatment (B), both in 2005 and 2006. No significant differences were observed between treatments A, C and D. No clear connection could be made between TSNA accumulation and conservation with various pressure or moisture in bales. In the 2007 experiment, low to null TSNA accumulation occurred during storage in either ambient or 4 °C temperatures, whereas a significant increase was consistently observed at 30 °C, in both Burley and dark air-cured tobacco.