Sun-cured tobacco, Bastam, Iran Curing and subsequent getting older allow with the sluggish oxidation and degradation of carotenoids in tobacco leaf. This creates particular compounds within the tobacco leaves and provides a sweet hay, tea, rose oil, or fruity aromatic flavor that contributes into the "smoothness" in the smoke. https://broadfar.com/heated-tobacco-shaping-a-safer-sustainable-smoking-future/