The nearest major airport is Indianapolis International Airport (IND / KIND). This airport has international and domestic flights from Indianapolis, Indiana and is 71 miles from the center of Purdue University.
Here is the official FDA definition of natural flavoring: Natural flavor is the essential oil, oleoresin, essence or extractive, protein hydrolysate, distillate, or any product of roasting, heating or enzymolysis, which contains the flavoring constituents derived from a spice, fruit or fruit juice, vegetable or vegetable juice, edible yeast, herb, bark, bud, root, leaf or similar plant material, meat, seafood, poultry, eggs, dairy products, or fermentation products thereof, whose ...
In other words, natural flavors can be pretty much anything approved for use in food. It's basically impossible to tell from a label what is in natural flavors unless the company has specified it on the label. A few of the vegetarian & vegan-oriented companies are doing this now, but the overwhelming majority of food manufacturers do not.