Ask a Distiller: What’s the Difference Between Sweet Mash and Sour Mash Whiskey?

Whiskey is a product of several crucial decisions that impact both style and flavor. Choices like the base grain, barrel selection, and how long the liquid ages are all relatively self-explanatory. But the difference between using a sweet mash or a sour mash might not be as easy to grasp. The terms aren’t totally unfamiliar — Jack Daniel’s famously stamps “sour mash” front and center on its iconic flagship bottle — but what they are and how they influence the whiskey is a bit esoteric.

So what exactly does sweet or sour mean in this context? And why would a distiller opt to use one over another? VinePair tapped John Schrepel, master distiller for Still Austin Whiskey Co. in Austin, Texas, to clarify why this decision is so critical in whiskey production.

To review the basics, the “mash” is the liquid produced by blending grains (typically corn, wheat, rye, or barely) with water and yeast to induce fermentation. Sometimes distillers will also add “backset” — liquid taken from a prior whiskey batch — to the mix as well. This is where sweet and sour mashes differ: A sour mash contains backset and a sweet mash does not.

There’s a scientific rationale behind adding backset to a mash. But for a distiller, the decision to make a sour mash with backset or a sweet mash without it can also be a matter of practicality and innovation.

“Using backset in a sour mash helps control the pH levels during fermentation,” Schrepel explains. “This can produce consistent results, which is important. Whiskey quality depends on how you’re cooking and fermenting the mash. If it’s fermented poorly, you’ll see inconsistency.”

The backset’s citric acid can also help ensure the mash’s acidity level lands within a specific range on the pH scale. Schrepel, for instance, keeps the pH between 5.2 and 5.5 over the course of the mashing process. Falling within the desired range allows the yeast in the mash to kick-start fermentation while minimizing the threat of bacterial contamination.

“Once you get that backset dialed in, you’ll gain the equilibrium you’ll need to get the desired consistency over time unless you run into technical issues with your equipment,” Schrepel adds. “In a way, the basics of sour mash distilling operate on the principles of KISS: Keep It Simple, Stupid.”

Since a sour mash’s guardrails can lead to greater reliability in the finished product, the tactic is ideal for industry heavyweights with large-scale productions like Jack Daniel’s and Jim Beam. It can also be a smart technique for craft brands seeking to ramp up their output.

Conversely, smaller distilleries within the craft sector like Still Austin employ the sweet mash method with greater frequency. Schrepel points out using the sweet mash technique doesn’t disrupt the ability to achieve consistency. It does, however, require extra work to maintain equilibrium.

“You can still get consistent results from a sweet mash,” he says. “You just have to be on top of things. You need to constantly be checking on it and tasting to make sure the citric acid doesn’t need to be adjusted to bring the pH down to the right level.”

This hands-on approach can also lend itself to greater creative control. According to Schrepel, the sweet mash method gives him the freedom to experiment and release bottles that aren’t necessarily conducive to big-brand rollouts.

“What we can do by using sweet mash distilling is focus on making whiskeys the big guys can’t,” he says. “For example, we make two different whiskeys from blue corn and red corn. You can’t really scale up with those grains.”

So which method is better: the sour mash style that uses backset to produce more efficient consistency, or the sans-backset sweet mash technique that leaves more room for creative expression? Schrepel says it’s a matter of preference, but he also highlights one element that ultimately unifies the two methods.

“There is no right or wrong answer here,” he says. “However, if you’re getting poor- quality grains for your mash bill, it doesn’t matter what method you use. You can’t use bad grains to make good whiskey.”

The article Ask a Distiller: What’s the Difference Between Sweet Mash and Sour Mash Whiskey? appeared first on VinePair.