Kentucky bourbon is made through a meticulous process that involves distilling a fermented mash of grain, yeast, and water. The specific combination of grains used in the mash, known as the “mash bill,” is what gives bourbon its distinct flavors and characteristics.
The key requirement for bourbon is that the mash bill must contain a minimum of 51% corn. However, it is important to note that the majority of bourbons have a higher corn content, typically around 70%. Corn contributes to the sweetness and richness of the final product.
In addition to corn, other grains are used in the mash bill to add complexity and flavor. Rye, malted barley, and wheat are commonly chosen as the “flavor” grains. Each grain brings its own unique qualities to the bourbon. Rye, for example, can add spiciness and boldness, while wheat can create a softer and smoother taste.
The first step in making Kentucky bourbon is milling the grains. This involves grinding them into a coarse powder to expose their starches. The milled grains are then mixed with water to create a mash. The water activates enzymes in the grains, converting the starches into fermentable sugars.
After the mash is prepared, yeast is added to initiate fermentation. Yeast consumes the sugars in the mash and converts them into alcohol. Fermentation typically takes several days to complete, during which time the yeast produces heat and carbon dioxide.
Once fermentation is finished, the resulting liquid is known as “distiller's beer” or “distiller's mash.” This beer is then distilled using traditional copper stills. Distillation involves heating the liquid to separate alcohol from other impurities and unwanted substances. The result is a clear, high-proof spirit known as “new make” or “white dog.”
After distillation, the new make is transferred to charred white oak barrels for aging. Bourbon must be aged for a minimum of two years to be legally considered bourbon. The aging process is crucial as it allows the spirit to develop its flavors and characteristics. The charred oak barrels impart flavors such as vanilla, caramel, and spice, while also adding color and complexity to the bourbon.
During the aging process, the bourbon interacts with the wood, undergoing chemical changes and maturing over time. The longer the bourbon ages, the more it takes on the flavors of the barrel, resulting in a smoother and more refined final product.
Once the bourbon has reached its desired age, it is ready to be bottled. Some bourbons are bottled straight from the barrel, while others may undergo additional filtering or blending before being bottled. The bottling proof is often adjusted by adding water to achieve the desired alcohol content.
Kentucky bourbon is a product deeply rooted in tradition and craftsmanship. The careful selection of grains, meticulous fermentation, distillation, and aging all contribute to the creation of a unique and flavorful spirit. Each step in the process plays a crucial role in producing the distinct taste and character that bourbon enthusiasts appreciate.