Solar-cured tobacco, Bastam, Iran Curing and subsequent ageing allow for for the gradual oxidation and degradation of carotenoids in tobacco leaf. This makes specified compounds inside the tobacco leaves and offers a sweet hay, tea, rose oil, or fruity aromatic flavor that contributes for the "smoothness" from the smoke. https://broadfar.com/nuso-heated-tobacco-smarter-alternative-to-traditional-smoking/