Study on the Chemical Composition of the Mainstream Cherry-red Tobacco Smoke

Introduction Cherry-red tobacco is a flue-cured variant that possesses a distinctive "sticky rice" flavor, which is highly valued by the tobacco industry. However, the value of cherry-red tobacco is dubious due to the possible health risks associated with tobacco-specific nitrosamines (TSNAs).Objective This study aimed to investigate the chemical origin of the "sticky rice" flavor and to assess the potential health hazards of TSNAs.Methods An optimized untargeted analysis with gas chromatography-mass spectrometry and a targeted analysis with liquid chromatography-tandem mass spectrometry were conducted.Result Over one hundred compounds were identified and quantified. Cherry-red tobacco and the normal control showed significant differences in forty-three of these compounds. Pyridine alkaloids and their derivatives constituted the main difference. Nornicotine, a demethylated product of nicotine in cherry-red tobacco, was confirmed to be pyrolyzed to 3-ethylpyridine, 3-methylpyridine, and other homologues, and transferred to the smoke during smoking. The smoke of cherry-red tobacco was found to contain much higher levels of N'-nitrosonornicotine, a TSNA derived from nornicotine, than that of normal flue-cured tobacco, while the levels of the other detected TSNAs were lower. The two types of tobacco had similar total amounts of the four TSNAs.Conclusion The pyrolysis of nornicotine into 3-ethylpyridine and its homologues during smoking may be the main cause of the "sticky rice" flavor of cherry-red tobacco. The level of TSNAs does not reflect the difference in health risk between cherry-red tobacco and the control.