What is sour mash whiskey?
Sour mash uses spent distiller’s beer (alcohol-free fermented mash wort from a previous fermentation batch) to condition each new fermentation batch. This is also referred to as “backset”. In some recipes as much as 25% is added to each new fermentation. This promotes consistency from batch to batch. Sweet mash means using a fresh yeast mixture for each new batch, and no spent beer.
