When whiskey is entered into the barrel it undergoes many changes. There are many factors in these changes and barrel entry proof is an important factor. This proof has changed over the past two centuries and these changes impact the flavor of the Bourbon we are drinking. The Bourbon of James Crow would have a very different flavor than the Bourbon of the 21st century. To best understand these changes we should look at the Bourbon of the 1830s when Crow was distilling his legendary whiskey.

The 19th century was a time of many advancements in technology but it was not until the end of the century before technology made glass bottles affordable to distillers and they started bottling their own product. In Crow’s time of the 1830s whiskey was sold by the distiller in the barrel. Consumers would purchase the whiskey from the liquor store or tavern and most often they would bring their own flask or jug to hold the spirit. These flask and jugs were filled straight from the barrel so the distiller wanted a whiskey that was considered palatable straight from the barrel. They filled their barrels with whiskey that was 100 to 103 proof. The proof could go up or down with aging, depending upon the conditions of the storage of the barrel, so that the consumer was getting whiskey somewhere between 95 and 105 proof alcohol.

This higher concentration of water meant that the natural sugars in oak staves dissolved quicker into the whiskey. Most whiskey barrels were sold by the distiller at no more than two or three years of age so it was important to get the sweeter flavors from the wood at younger age. At the end of the century when bottling became an affordable practice for the distiller, they would increase the entry proof sometimes as high as 107 proof to make sure the proof stayed above 100 for bottling purposes.

Prohibition put an end to consumers being able to purchase their Bourbon directly from the barrel. With repeal came increased regulations for Bourbon. There came an official “Barrel Entry Proof” range of 100-110 proof. The lower limit of 100 was done because the tax was based upon 100 proof alcohol. The upper limit was set because of tradition. Barrels were still relatively inexpensive and the flavor profile was important. That would change in the next two decades. It was determined that people wanted lighter flavored whiskey and one way to do that was to increase the barrel entry proof.

In 1962 the barrel entry proof was increased to the 125 proof limit of today. This was done to save on the number of barrels needed to age whiskey and to lighten the flavor of the end product. It would take almost two more decades before the new maximum entry proof became the standard in practice as well as regulation, but it has done so. The resulting whiskey was lighter in flavor after 4 years of aging. It would take 8 years or more to achieve the richer bold flavors of the post Prohibition products.

The craft distilling movement is seeing a swing back to lower entry proof for whiskey. It costs more because it takes more barrels to mature the whiskey, but some distillers are seeing that balanced by having a richer tasting product at younger age. That means they lose less to evaporation during aging and it is their hopes that the cost of the barrels will be made up for by a better tasting product and more bottles to sell.

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Photos Courtesy of Maggie Kimberl