Sunshine-cured tobacco, Bastam, Iran Curing and subsequent getting older enable with the slow oxidation and degradation of carotenoids in tobacco leaf. This makes specific compounds in the tobacco leaves and offers a sweet hay, tea, rose oil, or fruity aromatic taste that contributes into the "smoothness" with the smoke. https://broadfar.com/oraco-global-trends-in-heat-not-burn-products/