How does white dog (raw, unaged whiskey) develop it’s array of flavors? A whiskey’s final flavor mostly comes from the way that the distillate interacts with the charred wood barrels. Here are great articles on this subject.
Fungus play a vital role in the seasoning of white oak for whiskey barrels. Of Quercus Alba and Eumycotians. Chuck Cowdery
Check this out: Visual and taste changes in unaged parent whiskey after 20 years in two different kinds of oak barrels: Advances in the Ageing Chemistry of Distilled Spirits Matured in Oak Barrels
This infographic is from The Chemistry of Whiskey. Great article if you click the link.