Often, you’ll see that a bottle of American whiskey is called Tennesse whiskey or Kentucky straight or simply bourbon. Since I have already reviewed Knob Creek 9 Single Barrel, I should probably take the time to explain the process of making bourbon. You can refer to my previous post in single malt production to explore the differences and similiarities. My post on What are the Varieties of Whiskey also contains related information.
Bourbon production requires a minimum of 51% corn. To that, a distiller will also require some malted barley, rye, and/or wheat. The same distillery may choose to play with those ratios and produce a large variety of whiskies, each presumably having its own distinct taste. More corn makes the product sweeter, more rye adds some spice. The mix is called the mash bill and typically consists of 70% corn.
The ground corn is cooked in water and the other components are added while cooling down the initial ingredient. Mash from prior distillation may be added, resulting in what is known as sour mash. Once the other ingredients have been mixed in, the mix is allowed to cool again and the malted barley is added. This allows the starch to turn into sugar. The barley provides the enzymes required for the conversion. Yeast is then added and fermenting begins. Distilleries keep their own yeast character and believe that the yeast they use has a direct influence on the final product. Fermenting now begins and results in a beer of average commercial alcohol content after a few days.
The beer must now be distilled using stills. The alcohol is separated from the beer in the stills using steam to evaporate the alcohol which is then condensed into a spirit of between 60 – 80% alcohol by volume. A lower alcohol content gives more character to the whiskey, thus most producers will condense to a lower alcohol content. A second distillation takes place and in Tennesse, the product may be filtered through hard sugar maple charcoal.
The product is then matured in charred oak barrels. The charred wood will impart its colour and flavour to the product. The charring of the wood will result in sugars that will also give some caramel flavour to the final whisky. The whiskey is matured for however long the manufacturer wishes, but a minimum of 2 year is required. The warehouse also plays a role in the final flavour profile of the product. A warmer warehouse climate makes for quicker reaction and vice versa.
The product is then cut before bottling to about 40% alcohol by volume though, as noted in my Knob Creek Single Barrel review, it can be sold at much higher strength.
In a nutshell, that’s pretty much it. There are a whole bunch of legal requirements and variations on the theme and processes that have much more specific rules attached, but the basic principles are the same across all bourbons.
I’ll be reviewing more bourbons in the future, so keep an eye out. If you have any suggestions, I’d be glad to try them out.