Sour Mash

Sour mash is a distillation process — not a flavour — in which a portion of the spent mash from a previous batch is added to each new fermentation, acting as a natural acidifier that ensures consistency and continuity of flavour across batches. While sour mash whiskey is technically a production method rather than a separate category, it is the process behind virtually all Tennessee whiskey and a significant proportion of American bourbon. Jack Daniel's Tennessee Whiskey is perhaps the world's most famous sour mash expression, but the category extends far beyond that single iconic brand to include a wide range of bourbons, Tennessee whiskeys and craft American spirits. Understanding the sour mash process is key to appreciating why American whiskey tastes the way it does.