CORESTA Meeting, Agronomy/Phytopathology, Suzhou, 1999, AP40

Influence of curing procedures and nornicotine potential on TSNA formation in three varieties of dark tobaccos

SEITA, Institut du Tabac, Bergerac, France
Due to their genotype and curing mode, air-cured tobaccos usually have a higher content in tobacco-specific nitrosamines (TSNA) than Virginia flue-cured varieties. Two studies were conducted at the Bergerac Institute in 1996 and 1997 to measure the effect of these factors on dark air-cured varieties. Samples for chemical analyses were taken at the main stages of curing. The objective of the 1996 experiment was to assess the influence of the curing mode on TSNA formation in three varieties of dark tobacco with various nornicotine (NN) potentials: ITB1000 and ITB1105 (low potential), and TC01 (high potential). The curing procedures applied were: natural air-curing in stalks (ACT) or in leaves (ACF), curing of leaves in warm air (FC), and curing at 25°C of lamina separated from the stem after yellowing (ACL). After curing, NN content in TC01 was 5 and 6 times higher, and TSNA content 3 and 4 time higher than in ITB1000 and ITB1105, respectively. Curing in leaves (ACF, FC) produced the lamina with the highest NN content. Warm air curing (FC) produced the lamina with the highest content in TSNA. In the 1997 experiment, 9 curing procedures were applied to var. ITB1000, combining curing type (in stalks or leaves), barn type (traditional barn, plastic shed, conditioned room) and temperature of the curing stages. The lowest TSNA contents were obtained with traditional barns and plastic sheds. High temperatures during the two latter stages of curing considerably increased TSNA content. A high NN potential and high temperatures after the yellowing stage generate high TSNA contents.