Solar-cured tobacco, Bastam, Iran Curing and subsequent growing old enable for that slow oxidation and degradation of carotenoids in tobacco leaf. This makes particular compounds during the tobacco leaves and gives a sweet hay, tea, rose oil, or fruity aromatic taste that contributes towards the "smoothness" of your smoke. https://broadfar.com/oraco-global-trends-in-heat-not-burn-products/