Sun-cured tobacco, Bastam, Iran Curing and subsequent getting older let to the gradual oxidation and degradation of carotenoids in tobacco leaf. This creates specific compounds from the tobacco leaves and provides a sweet hay, tea, rose oil, or fruity aromatic flavor that contributes on the "smoothness" with the smoke. https://nmate13467.scrappingwiki.com/1364540/cigarettes_no_further_a_mystery