I only just realized that synthetic vanillin (in a discussion about producing vanillin from GMO yeast) is made from coal tar, or more importantly, lignin from paper mills. So I got to thinking about how aged puerh will express various "vanilla" and "white dessert" flavors, and now wonder if that's just me drinking vanillin or something similar from the decomposed lignin in the leaves and stems.
May as well add: http://www.cooksillustrated.com/taste_t ... la-extract
Is it important to have some vanillin flavor to help appreciate the complexity of the other flavors? Why does aged sheng puerh express these flavors, but not other heicha with comparably meaty leaves? Shu sort of does, but not nearly the same way or the same strength.