Sunlight-cured tobacco, Bastam, Iran Curing and subsequent getting old enable with the sluggish oxidation and degradation of carotenoids in tobacco leaf. This produces specified compounds in the tobacco leaves and provides a sweet hay, tea, rose oil, or fruity aromatic flavor that contributes to your "smoothness" in the smoke. https://broadfar.com/oraco-global-trends-in-heat-not-burn-products/