Is Jack Daniels sour mash whiskey the same as bourbon?
What is sour mash Tennessee whiskey?
If a whiskey uses the Sour Mash process, some of the spent mash from a previous batch of whiskey to the new mash. This old mash consists of fermented and distilled mash with dead yeast in it. The sour mash process is very useful to distillers because it gives them more control over the pH of their mash.