Jack Daniels could be marketed as a Bourbon if they didn't use maple for the charcoal. A 'Straight Bourbon' has additional requirements. A bonded Bourbon has even more. The 'Lincoln County Process' defines a TN whisky, and it's basically just a maple charcoal bath that gives the product a head start on aging. It results in the product beng ready for sale with less time in the barrel and less resultant 'angel's share' loss. They charge a premium for this. Go figure.
Only a small amount of fermenting distiller's beer is added back to the next fermentation vessel in moden large scale 'sour mash' operations. This stuff is 'sour mash' in name only. The distilleries have various methods of pitching their yeast cultures, the primary consideration being speed of fermentaion. They want it done quickly, so the beer isn't contamnated by airborne organisms. Typical would be 300 gallons of fresh working culture added to a 10,000 gallon fermentaion vessel. It's working like a rolling boil in a matter of a few hours. At least one major distillery uses Red Star to propagate their yeast culture and they receive it dry in big bags. It's not a trade secret. Buffalo Trace is quite open about their methods. They make great Bourbon.
