Erik Behind the Bar

Ever look at a bottle of Jack Daniel's and seen the words "Sour Mash"? Someone asked me about this a few months ago, and I thought I'd start this column with that. Unfortunately, I don't remember who asked, so I can't give them proper credit for their curiosity. Whoever it was, thanks for getting me started!

To understand sour mash, first we need to know what mash is, as it relates to the process of brewing. Mash is a mixture of grain and water (and sometimes additional ingredients). Creating a mash, or Mashing, is the first step on the road to making grain alcohol. That makes it essential to beer, whiskey, some vodkas, most gin, but not wine, brandy, rum or tequila. Since the sour mash technique is used almost exclusively for whiskey, we'll focus on that.

Whiskey starts its life as grain, and in the case of most sour mash whiskey, that grain is corn, blended with rye, wheat, barley, and others. The grain contains high amounts of starch and low amounts of sugar.

Alcoholic fermentation requires sugar, so the grain is immersed in water and heated. This prompts natural enzymes in the grain to convert the starch into sugar. This process is called "mashing" the grain, and the water-and-grain mixture is called the "mash".

Once the brewer judges the concentration of sugar to be right, the mash is filtered, removing the spent grain in a process called "lautering". The liquid, now heavy with sugars and other essences of the grain, is called the "wort", and the spent grain is called "sour mash".

The wort goes on to be fermented (where it turns into "beer") and then distilled. After aging a while in oak, they call the stuff whiskey.

The sour mash fairs much worse. Often, it is discarded. In older days, the mash would be mixed into food for livestock, so it was also called "feed mash".

In the case of sour mash whiskey, a portion of the sour mash is added to the new mash of each batch. The process appeared just after 1823, when Scottish chemist Dr. James C. Crow began working for Old Oscar Pepper Distillery. The acidity in the spent grain helps to control harmful bacteria in the new grain, and also creates a more consistent flavor across many batches of whiskey. Eventually, the good doctor went to work for the Johnson Distillery, and his knowledge began to spread. The Johnson Distillery went on to become Old Taylor, and the Old Oscar Pepper Distillery is now the Woodford Reserve Distillery.

So there you have it. Sour Mash Whiskey takes a little of the old batch and adds it to the new batch. Think of it like the sourdough bread of whiskeys!