Visualizing the penetration of flavor additives into tobacco leaf by ambient pressure laser desorption ionization/post-photoionization mass spectrometry imaging

Understanding the penetration behavior of flavor additives in tobacco leaf during casing process is crucial for the production of tobacco products. Here, atmospheric pressure laser desorption ionization/post-photoionization mass spectrometry imaging (AP-LDI/PI MSI) was utilized to study the flavor additives penetration in tobacco leaf. The cross section of tobacco leaf with and without flavor additives were scanned by focused laser beam at ambient condition, and the desorbed species were ionized by dopant-assisted post-photoionization setup. The distributions of the endogenous metabolites and exogenous model flavor molecules could be well imaged with 5 μm spatial resolution. It was found that the penetration efficiency varies significantly among different flavor additives. Increased temperature and humidity could enhance penetration efficiency by promoting molecular thermal motion and accelerating cuticle hydration. Finally, the penetration process of a commercial flavor additive solution was visualized and evaluated, which would provide valuable guidance for cigarette casing technology.