"A big difference between Tennessee Whiskey and Bourbon is the Sour Mash!"
A line I've heard several time at a bar...and it's false. Sour Mash or "Sour Mash Whiskey" are commonly misunderstood terms. Let's break this down:
What is Sour Mash?
It’s used liquid stillage leftover after the initial distillation process.
"Stillage? Explain please..."
In the distillation process, the fermented grains are heated in the still where alcohol is separated from water and solids. The solids are removed (a great food source for livestock!) and the leftover liquid (stillage) is sent to mix with new grains and water for the next batch in fermentation.
"So, this stillage is how Jack Daniels (a Tennessee Whiskey) gets its sweet flavor?" Negative.
"Okay, well what is the significance of this?" In short, it has nothing to do with a sour taste and everything to do with consistent production operations.
"What? That sounds lame. There’s nothing magical about Sour Mash?"
Absolutely! If you are a distiller the practice of using sour mash magically saves you Benjamins. Lots and lots of Benjamins. The stillage helps balance the water pH, is great feed for the new batch of yeast and slows bacteria growth (a distiller’s nemesis). Consistent batches equal cost savings. In fact, using sour mash is a common industry practice. Most whiskies could add it to their label if they wanted to.
"Why add it on the label if it’s not unique to the bottle of whiskey?" It sounds a lot sexier than “yeast” or “water” which are also commonly used as well.
So, the next time a “connoisseur” mentions anything about “the sweet Sour Mash flavor,” politely hand them a bowl of lemons and call bullsh*t!