Solar-cured tobacco, Bastam, Iran Curing and subsequent getting old allow with the gradual oxidation and degradation of carotenoids in tobacco leaf. This makes selected compounds during the tobacco leaves and gives a sweet hay, tea, rose oil, or fruity aromatic taste that contributes to the "smoothness" of your smoke. https://broadfar.com/non-combusted-cigarettes-a-safer-alternative-or-just-a-myth/