Sun-cured tobacco, Bastam, Iran Curing and subsequent getting old make it possible for for the sluggish oxidation and degradation of carotenoids in tobacco leaf. This provides particular compounds during the tobacco leaves and provides a sweet hay, tea, rose oil, or fruity aromatic taste that contributes to your "smoothness" https://broadfar.com/oraco-global-trends-in-heat-not-burn-products/