Sunlight-cured tobacco, Bastam, Iran Curing and subsequent aging allow for for your slow oxidation and degradation of carotenoids in tobacco leaf. This provides specified compounds during the tobacco leaves and provides a sweet hay, tea, rose oil, or fruity aromatic taste that contributes to the "smoothness" from the smoke. https://broadfar.com/nuso-heated-tobacco-smarter-alternative-to-traditional-smoking/