Louisville Stories and Tips

How They Make American Bourbon Whisky

Double Still Distillation Photo,

Rather than to fill up three reviews with the details of the full process, I thought it best to tackle that as a separate topic. So to that end, I offer. . . How they make American bourbon whisky.

In order to be called bourbon whisky in America, the law requires that a grain mixture using at least 51% of corn have to be used. Additionally, the liquid must come out of the evaporation process at least 160 proof and must be stored for a minimum of two years in new char oak barrels and that there would be no additives to give the product color or flavor. While clear “white dog” is the original alcohol product that comes out of the distillation process, the aging process (typically four to seven years) is what gives the golden brown coloring and the smooth caramelized flavor.

Distilling whisky has been part of the American fiber dating back to the 18th century. As local owners of stills started to sell the product, the business of making bourbon whisky was started. By 1911, there were nearly 200 distilleries in Kentucky. Unfortunately Prohibition (1920-1933) caused huge problems for the owner operators of stills throughout the country, shutting down those who chose to be in compliance with the law. Others continued to operate in the shadows, creating a significant underground economy at a time when the country was in significant financial distress.

After prohibition the country saw production restrictions and a number of industry consolidations that ultimately resulted in a dramatic reduction of companies in the bourbon business in Kentucky. Today there are just nine distilleries operating in the state. One may ask “Why Kentucky?” to which we learned that it is here that the best natural spring waters are available. The limestone found in the ground serves as a water purifier, assuring that there is no iron or any other minerals that can adversely affect the smooth taste of the bourbon.


The Process Itself

While the grain "recipe" varies from company to company, all must use a minimum of 51% corn. The remaining 49% is typically rye and barley, although in the 1950s Marker’s Mark changed their family recipe to replace the rye with the sweeter and more subtle wheat. Since that time, other distillers have created specialty bourbons that also feature wheat. Once the grains have all been milled or ground to a rather fine consistency, the malt is cooked. Once cooled, yeast is added to essential “eat” the sugars, expelling carbon dioxide as the huge vats bubble. No heat is used at this step of the process. The fermentation room where this takes place is very pungent smelling much like a frat dorm room on Monday after a weekend keg party. The mash is largely like beer, only without the fizz that carbonation creates.

After three or four days of fermentation, the mixture is separated so as to remove the grains from the liquid. This is the distillation step. Through an evaporation process, the gases rise and then condense into liquid. The first step product is also called low wine and typically is put through another distillation that results in the final product that will be barreled for aging. The remaining grain mixture is typically sold to local farmers as livestock feed.

Barrels are white oak and have been uniformly charred on the inside. The filled barrels are then warehoused in a “rack” configuration on their side. As the barrel and liquid temperatures fluctuate with the seasons of the year, the liquid penetrates the wood of the barrel in the summer. In the winter, the liquid retreats back to the interior of the barrel with little in the actual wood itself. This expansion and contraction is essential to making good bourbon whisky and why you will find distilleries in areas such as Kentucky, Tennessee, and Virginia where there are four distinctive seasons. Many distilleries rotate the barrels throughout the rack house in order to provide a more uniform aging process.

After the aging process has been completed, the contents of the barrels are emptied through a filtering process to assure the purest product is bottled. Once bottled, labeling, and packaging occurs. The bourbon is then ready for shipment.

You may wonder about what they do with the now “used” barrels. They are typically sold to distilleries overseas, particularly in the UK. When we took the Dewar’s Distillery tour in Aberfeldy, Scotland we were told they bought all of their barrels from American bourbon distilleries. At Jim Beam, visitors could buy used barrels (half or whole) for uses around the house and yard. During our tour at Marker’s Mark we learned of “redneck whisky” which is when someone buys and takes a used bourbon barrel and fills it up with water in hopes of soaking out the alcohol from the oak barrel. All I could think of was “YUCK!”

NOTE: All photos with this review are from the tour of Marker's Mark as they were the only distillery we visited that took us to see all of the steps of the process.

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