Sun-cured tobacco, Bastam, Iran Curing and subsequent getting older allow for that gradual oxidation and degradation of carotenoids in tobacco leaf. This creates sure compounds inside the tobacco leaves and provides a sweet hay, tea, rose oil, or fruity aromatic taste that contributes on the "smoothness" in the smoke. https://broadfar.com/non-combusted-cigarettes-a-safer-alternative-or-just-a-myth/