I have heard many people, distillers and consumers alike, state that whiskey gets over 70% of its flavor from the barrel. This is true with real old whiskey. In fact, I have blind tasted twenty-year-old Bourbon against a rye of the same age and the tasters could not tell which whiskey was the Bourbon, and which was the Rye. The wood from the barrel dominated the flavor. However, most whiskeys sold are not nearly that old and I believe there are other factors than the barrel that contribute to the flavor of the whiskey. The younger the whiskey the less the barrel plays a role, at least in a good way. Lincoln Henderson once told me that “You get a lot of flavor from the barrel in the first six weeks of aging. Then you spend the next four years trying to get rid of those flavors.” In other words, the first flavors are harsh and unpleasant but as time works its magic, those flavors break down into more pleasant compounds as the whiskey “mellows” with the aging process. Lincoln also was fond of saying that “You need to get it right every step of the way. If you do not have good new make, then all of the aging in the world will not make it a good whiskey.”

I believe that there are six sources of flavor for the whiskey and maturation is just one of the sources. I base this upon the old Stitzel-Weller “Five Keys to Success” advertisements and added another key, or source of flavor, and that is bottling. Here are the sources of flavor in my opinion:

  1. Grains: Grains play a huge roll in the flavor of the whiskey. Most people talk about the mash bill and the percentages of grains used and that is an important part of this source of flavor. However distillers are showing the variety of grain used also plays a big role in the flavor. Using heirloom corn, rye and barley does change the flavor. Some distillers are using non-traditional grains such as oats, rice and buckwheat. The grain has an impact in the amount of natural oils and amino acid compounds in the grain. Grain is the first source of flavor.
  2. Water: Water is essential to the process of making whiskey. It has become less important as many large, city-based distillers, are using water treated with the Reverse Osmosis process to take out chemicals found in the city water supply. However, distillers located away from cities where the groundwater is still pure in deep wells or springs have water that is rich in different minerals that do add to the flavor of the whiskey. It is important to have water without bad flavor components, such as iron. Water may have a small impact on the flavor,  but if the water is not good that small impact will ruin your whiskey. Water is the second source of flavor.
  3. Fermentation: Yeast is an important source of flavor. There are thousands of yeast strains and not all of them make good whiskey. Each strain of yeast creates its own flavors. Four Roses is a good example of this with their five different yeast strains and two different mash bills making ten different whiskeys. However, yeast alone does not create the flavors in fermentation. Bacteria also creates flavors and not all of them good. That is why most distilleries are now using stainless steel mash tubs. Wooden fermenters, even those made from cypress wood which does not have an impact on the flavor of the beer fermenting in them, are hard to keep clean and can lead to bacterial infections of the mash, ruining the fermentation. The length of the fermentation can change the flavor of the beer. Most distilleries do a three day fermentation but some like Old Forester are fermented for five days or even longer. Fermentation is the third source of flavor. The amount of back set, if any, changes the flavor of the beer. Many distillers are using the sweet mash method now with no back set of spent beer.
  4. Distillation: The type of still being used will have an impact on the whiskey produced. Pot stills, column stills, or a hybrid of a pot with a small column attached all make different flavors. The amount of copper used to make the still will impact the flavor of the whiskey it produces. The proof at which the whiskey is made makes a huge difference in that the closer to pure alcohol (the higher the proof), the less flavor from the grain, water and fermentation in the final product. There is also where the heads and tails cuts are made that can change the flavor of the whiskey. Distillation is the fourth source of flavor.
  5. Maturation: There are many factors in this process that change flavor. Starting with the barrels. Smaller barrels, those of less than 53 gallons, such as 30 gallons, 10 gallons or even 5 gallons, have thinner staves and less toasting and tend to be producing flavors dominated by the wood tannins alone. The amount of time spent aging the whiskey is also a factor. The longer the whiskey is exposed to the wood, the more the wood dominates the flavor of the whiskey. Where and how the whiskey is stored plays a role in the flavor. How much air circulation around the barrel is an important factor to aging. Palletized barrels lose the impact of the top head which will always be dry. Brick warehouses have less extreme swings in temperature than iron clad warehouses. Warehouses in a city will age whiskey differently than those in the countryside and even those in the country will age differently if they are on a hilltop compared to those in a valley. Heated warehouses age differently than unheated. Whiskey being aged in Michigan will age differently than whiskey aged in Texas as the longer, colder winters up north means either a heated warehouse or a much shorter time of the whiskey being cycled in the wood. The barrel entry proof makes a difference in the final flavor produced in maturation. Lower barrel entry proof allows more natural sugars to come out of the wood at an earlier age since sugar dissolves better in water than in alcohol. It also means the distiller does not need to add as much water when proofing the whiskey for bottling. There are many factors to consider in the aging process and maturation is the fifth source of flavor.
  6. Bottling: When a distiller bottles a whiskey there are many thing to consider that will impact the flavor of the final product. The first is filtration. Filtration is done to remove bits of charcoal created in the aging process as well as many oils that make the whiskey cloudy when it gets cold. The more the whiskey is filtered, the more flavor that is also removed. This can be a very good thing in super old whiskeys as filtration will remove many bitter tannic flavors and allow the sweeter caramels and vanilla compound to come forward in very old whiskey. However, in younger whiskey filtration can remove flavors and natural oils and make the whiskey thin and watery. The proof the whiskey is bottled at has an impact on the flavor. Generally, higher proof whiskey needs less filtration than lower proof whiskey to keep it from getting cloudy when chilled. The age of the whiskey to be bottled is important. Different ages of whiskey are also used in the bottling of the final flavor profile, creating different flavors for brands from the same whiskey. Bottling is the sixth source of flavor.

There are six sources of flavor for whiskey. Each plays a role in the flavor of the final product. I believe in a well-crafted whiskey every source has been done correctly and contributes its fair share to the final product. In the end, I think the flavor of the final product will be dominated by the maturation process but I think its share of the flavor is more like 55-60% than 70% or more, as some claim. The exception to this is whiskeys aged for over 15 years that naturally have more wood flavors from the barrel.

Photos Courtesy of Rosemary Miller