Solar-cured tobacco, Bastam, Iran Curing and subsequent getting old enable for your gradual oxidation and degradation of carotenoids in tobacco leaf. This produces specific compounds inside the tobacco leaves and offers a sweet hay, tea, rose oil, or fruity aromatic taste that contributes on the "smoothness" with the smoke. https://broadfar.com/heated-tobacco-shaping-a-safer-sustainable-smoking-future/