Sunlight-cured tobacco, Bastam, Iran Curing and subsequent aging allow to the slow oxidation and degradation of carotenoids in tobacco leaf. This creates certain compounds while in the tobacco leaves and offers a sweet hay, tea, rose oil, or fruity aromatic taste that contributes for the "smoothness" on the smoke. https://broadfar.com/non-combusted-cigarettes-a-safer-alternative-or-just-a-myth/