Immovable Yeast

There’s a certain amount of mystery, even superstition--call it distiller’s instinct if you prefer--in whiskey-making. For instance, some distillers add hops to their yeast. They can’t say why, other than that they’ve always done it that way and they don’t want to mess with a good thing.

Still, most distillers are fairly open about their methods. They readily talk about their “mash bill” (the percentage of grains they use). More corn makes a sweeter whiskey, while more rye gives a dry, dense, spicy quality, remotely similar to the flavor of rye bread. Wheat, which substitutes for rye in Maker’s Mark and some United Distillers brands (Old Fitzgerald, W.L. Weller, Rebel Yell), makes for a smoother whiskey.

They’ll eagerly tell you exactly how they cook their grains before adding the yeast, and how much “backset” they add to the mash from the previous batch. “Backset,” which is what emerges from the bottom of the still after the alcohol has been stripped from it, is the famous sour mash of sour mash Bourbon. It gives continuity to the flavor, and its mild acidity holds down undesirable microbes.

And distillers readily tell you the proof at which they barrel their whiskey and how long they age it (well, government regulations make this a matter of public record).

The one thing they protect fervently is their yeast. Yeast gives the fruity dimension to Bourbon, the aromas of peaches or berries or tropical fruits. It’s the second most important element in flavor, right after aging, and there are far more strains than you can imagine.

Some yeasts have been in distillers’ families for a century or more. And it wouldn’t do to show an unhealthy interest in them, pardner.