By: Scott Ritenbaugh
Whiskey production at its simplest is converting starch (from grains) into sugar using enzymes (malted barley), converting that sugar into alcohol by adding yeast, and then separating the alcohol from water and solids using heat.
Grain is milled, or ground, to maximize its surface area in order to expose as many of the starches in the grain as possible. The milled grain and water then go into a cooker.
The goal of cooking is to soften up or liquefy, enough of the grain to maximize the amount of starch that can be converted into sugar. After the grain has had enough time to cook, enzymes are added, traditionally in the form of malted barley. While any grain can be malted, barley is used because it has the highest enzymatic content of any malted grain. It is these enzymes that convert the starches from the grain into sugar. Once this conversion process finishes, the grainy liquid, or mash, is pumped into the fermenter.
In the fermenter, the goal is to turn all that newly created sugar into alcohol. This is done with yeast. Once yeast is added, the fermentation process starts and can take from 3-7 days for the process to complete. The more sugar the yeast eat. the more alcohol they produce. During fermentation dozens of different alcohols, often called congeners, are created. These congeners have tremendous impact on the flavor profile of the finished spirit. Once fermentation is complete, the mash in the fermenter is essentially beer, and it is pumped to the still.
Most of the alcohols created during fermentation have a lower boiling point than water. The distillation process uses heat to separate those alcohols from water and solids by vaporizing them. When the alcohol vapors reach the top of the still, they hit a condenser, a coil or tube surrounded with cold water, where they turn back into a liquid and run into a collection tank.
After distillation the spirit is put into a new, charred oak barrel at 125 proof or below. At this proof, the water to alcohol ratio is in the ideal range to extract the most flavor, color, and aroma out of the charred wood as possible. The longer the spirit ages, the more character it pulls out of the wood.