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