Study on the Chemical Composition of the Mainstream Cherry-red TobaccoSmoke

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 cherryred 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. Method: 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.