TSNA Accumulation in Controlled Curing Environment

The Council for Burley Tobacco funded this project in 2015; we are applying for a second year of funding because we would like to repeat it in 2016 so that we have two years of data. The 2015 crop is currently curing, so we do not yet have any data. An interim report was submitted in October. Experiments have demonstrated that the curing conditions optimal for high quality leaf are also those that favor TSNA accumulation, but the specific effect of the three factors involved in the curing process, temperature, relative humidity and airflow, have not been well defined. Previous studies have correlated TSNA levels with the ambient environmental conditions in commercial barns on farms, with or without various configurations of fans and vents, or in smaller experimental structures covered with plastic. This approach is severely limited by the confounding of the three environmental components. We can better understand the role of environmental factors on TSNA accumulation during curing, and so gain knowledge of the most important factor to control during commercial curing, by using a more controlled environment. Twenty four curing chambers in which temperature and humidity can be manipulated independently of each other were constructed. Thirty tobacco plants can be accommodated in each chamber at various combinations of temperature and relative humidity. TSNAs in the cured leaf from each environment will be analyzed and the quality of the leaf will be assessed. Previous work has shown that humidity has more effect on TSNAs than does temperature, although conversion at the end of curing was the same in all environments. As for the 2015 test, this study will investigate the effect of airflow as well as temperature and humidity on TSNA accumulation.