Actually The Tobacco you eat is green Tobacco not the cured and ripened leaves the green leaves is a vegetable and the alkaloids only start showing itself in force with the curing process. That is why the correct curing of tobacco is important for the crop of a tobacco Farmer hinges on it for the quality of the tobacco is determined by it. Bad quality low price good quality high price.
Take raw coffee beans they are white but once roasted and ground do they only release its flavor. Just as the taste of tea differs from green tea to dried tea.