Effects of air-curing environment on alkaloid-derived nitrosamines in burley tobacco

Abstract

Levels of nitrite and pyridine alkaloid-derived total tobacco-specific nitrosamines (TSNA) were significantly higher in tobacco leaf (normal or late harvest) air-cured at 32 degrees C/83% relative humidity (RH) than in more moderate environments, i.e., 15 degrees C/50% RH and 24 degrees C/70% RH. These constituents increased appreciably from day 10 to day 21 of the cure. The near-concurrent appearances of maximal total contents of TSNA [sum of N'-nitrosonornicotine (NNN), N'-nitrosoanatabine (NAT), N'-nitrosoanabasine (NAB) and 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone) (NNK)] and nitrite supports the concept that nitrite is a limiting and proximal precursor of total TSNA during the curing of tobacco. During a long curing period (50 days) at 32 degrees C/83% RH, nicotine and anatabine contents decreased, but TSNA contents increased in leaves of all harvest dates and stalk positions. These results support the view that nicotine and anatabine are precursors of TSNA. Measurement of nitrite and individual alkaloids during post-harvest processing of tobacco leaf may provide an index of the potential accumulation of alkaloid-derived nitrosamines.