Newman’s Whiskey Sour

Often made with sour mash whiskey (no relation).

References to the whiskey sour start around the 1860s. The basic recipe is as follows, as articulated in the July 28, 1895 edition of The (New York) World:

Whiskey sour has much to recommend it. This is another drink that should be shaken before taking. A heaping teaspoonful of powdered sugar should be dissolved in seltzer or apollinaris (a very small quantity) and mixed with the juice of half a lemon and a wine-glass full of whiskey. The glass should afterwards be filled up with shaved ice, and after the mixture is shaken it should be strained into a small glass. A Santa Cruz sour needs considerably less lemon juice, but the same quantity of liquor.

If you’re thumbing through old cocktail recipes, it’s important to know that there’s a difference between a whiskey sour and mentions of sour whiskey, which, in the first half of the 19th century and earlier, most commonly referred to sour mash whiskey, or whiskey made via the sour mash process. I’m not a distiller or a brewer by any means, but here’s my crude understanding (and experts should feel free to chime in and correct me) about what “sour mash” is.

The very simple explanation of how whiskey is made can be gleaned from the process used to make that “good corn whiskey,” moonshine.

What distinguishes one whiskey from another (including bourbons) is the composition of grains that go into the fermenting mash mixture at the beginning and how the distilled product is aged or filtered after being produced (or, in the case of moonshine, not aged or filtered after being produced).

Mash fermenting at the Maker’s Mark Bourbon Distillery on June 8, 2010. By DLSimaging, on Flickr (CC license).

A “sour mash” whiskey has an additional step to this process: some of the spent, already-distilled wort (that’s the liquid strained from the mash) from an already-run batch is added to the mash of the next batch.

In prior generations of distilling, this process saved water and sped up fermentation, the latter bit because the already-warm sour mash would make the temperature (and pH) more hospitable for yeast. Additionally, if there was any sugar that hadn’t been converted to alcohol before distillation, some would still be in the sour mash. But the sour mash process does some things that aren’t as quantifiable, too, adding additional flavor and ensuring a greater degree of consistency between batches.

While we could achieve these results through chemistry alone today, tradition still rules when it comes to brewing practice; most whiskeys (and all bourbon) are produced via a sour-mash process, with some distilleries using up to 40% “backset” (the industry term for the sour mash itself).

From a box sold in Nampa, Idaho.