Have you ever wondered where bourbon gets its rich and sometimes complicated flavor? Kentucky Bourbon Hall of Famer Mike Veach explained exactly where bourbon gets its multidimensional flavor at this year’s Filson Bourbon Academy.

Forrest and I have discovered that there are 6 sources of bourbon flavor. These include:

  • Grain That Goes into the Bourbon
  • Composition and Purity of the Water
  • Fermentation Process
  • Distillation Process
  • Length and Conditions of The Maturation and Aging Process
  • THE Bottling


As you already know, bourbon is defined as a spirit that contains at least 51 percent corn. Producers of fine bourbon are very particular, however, as to the specific types of corn that go into their product. Each corn variety – from Stowell’s Evergreen to Sugar Buns to Seneca Arrowhead corns – all produce distinctly different flavor profiles when used in bourbon. The corn is such an important element that Woodford Reserve has been reputed to own and only use corn from a particular field.

In addition to corn, other grains like rice, oats, wheat, and barley can have a great impact on the taste and texture of ones bourbon. (For you bourbon geeks, this mixture of grain is known as a mash bill). Woodford Reserve’s formula combines corn (72%), rye (18%), and barley (10%) to produce their bourbon, while Makers Mark relies on 70 percent locally grown corn, 16 percent red winter wheat, and 14 percent malted barley to achieve its flavor.


Kentucky has always been known for its mineral-rich limestone spring water (the eastern part of Kentucky sits atop a limestone shelf). It is this water that makes Kentucky bourbon so special, and so hard to replicate. Sure, a small producer could filter and remineralize his water to try to replicate or even improve on what is found naturally in Kentucky, but there’s nothing like the real thing, baby!

It’s important to note that the water used in bourbon must be completely free of iron. The presence of iron would turn the whiskey to a black color instead of the pleasing gold hue that develops during maturation.


There are two stages in the fermentation process that lends flavor to bourbon: aerobic and anaerobic phases. During the aerobic phase, yeast uses the air for its own growth. This process takes about 12 hours and produces carbon dioxide and water. As the air is used up by the yeast, the anaerobic phase begins. This is where the “magic” of whiskey making takes place as the yeast converts the sugars into alcohol and carbon dioxide in equal quantities.

During yeast fermentation, traces of other flavor and aroma compounds are also produced by yeast. The amounts of these compounds that are carried over into the whiskey during the distillation have a great effect on the character of the final whiskey produced.

Jim Beam understands the importance of fermentation and yeast strains when it comes to bourbon flavor. So much so that they’ve used the same strain of yeast since prohibition ended. It’s more than 75 years old—and it ensures the same Jim Beam consistency in every bottle. Four Roses also places a high priority on its fermentation process, and is the only bourbon Distillery that combines 5 proprietary yeast strains to make its product.


After bourbon is fermented, it is typically distilled using a Column Still – a pillar like formation with an upright pipe that allows the continuous distillation process. This pipe has floors with holes that are connected from the bottom to the top, and edges that bend upward in order to prevent liquid from flowing downwards.

The temperature of the column is designed so that the alcohol is completely gas at the top, with the beer is cooking at the bottom. The alcohol is removed at the top, the water with the grain fiber remnants comes out on the bottom (and is later used to make livestock feed), and the fumes are run through a copper pot, which improves the taste of the raw whisky. The again liquefied alcohol fumes are directed into vats and emptied into barrels at anywhere from 60% to 80% alcohol.

So with all that said, both the type of still used ( alembic, pot, or a continuous still) and the proof of the whisky coming out of the still plays an important role in bourbon flavor.


This is the part of the bourbon’s life cycle that most enthusiasts are familiar with. The raw whisky is emptied into barrels made of oak to mature and age. A number of different factors can influence the taste of bourbon at this stage, including the altitude that the bourbon barrel is stored at, the amount of char on the inside of the barrel, and the climate within the rickhouse.

The charring process – a procedure whereby the inside of the oak barrel is torched – is vital to the whole bourbon experience. Charring strengthens the barrel, removes bacteria and impurities that could destroy the contents of the barrel, and gives bourbon its one-of-a-kind characteristics.

The length of time that bourbon spends in its barrel also greatly influences its taste. The longer bourbon remains in its barrel, the more pronounced the flavor of the oak and char can become. Dont believe me? Try some white dog, and compare that with a Pappy Van Winkle 23-year old.

See what I mean?


The bottling process is the last factor that contributes to bourbon flavor. The shape and the glass of bourbon bottles can greatly enhance or reduce a bourbons flavor, in that one bottle of small batch bourbon may taste completely different from another small batch bourbon. Hell, in the case of many barrel-proof bourbons, the differences in proof may mean a complete difference in the way you perceive and taste the bourbon.

Some bourbons tend to “bloom” if the bottle is left open to sit for anywhere from a few hours to a few days. The next time you sit down to enjoy a snifter of bourbon, take a sip, then let the bourbon sit for varying amounts of time. Come back every now and then, give it a taste, and notice how much it has transformed!

If your sealed whisky is chemically stable when you buy it – and most commercially available spirits should be – it should remain flavorful years to come. However, if you decide to open the bottle, you are introducing other substances into the environment, and depending on what they are (molds, fungi, oxygen), they may shorten the shelf life and alter the taste of your whisky.

If you really want to actively keep a bottle around, consider further sealing the bottle with a layer of paraffin, as even factory seals are generally not completely airtight, and evaporation will occur.