Sun-cured tobacco, Bastam, Iran Curing and subsequent growing old enable for your slow oxidation and degradation of carotenoids in tobacco leaf. This provides selected compounds in the tobacco leaves and provides a sweet hay, tea, rose oil, or fruity aromatic flavor that contributes towards the "smoothness" of your smoke. https://broadfar.com/heated-tobacco-shaping-a-safer-sustainable-smoking-future/