Tequila Versus Bourbon – Aging

By: Michael Prentice

Bourbon and tequila have been two of the fastest growing spirit categories in the US. In fact many new tequila drinkers enter the market after enjoying bourbon. These drinkers are likely to opt for aged tequilas. But what do aged tequila and bourbon have in common, and what’s different?

Bourbon relies on aging for its bourboniness, whereas unaged tequila already has plenty of character. However, aging tequila can introduce complementary flavors, aromas, color and texture which can be appealing especially to drinkers of other aged spirits like whiskey, cognac, and rum.

Bourbon and tequila share a few things in common:

  • They are regulated by national authorities that set out the permissible production methods
  • They both have restricted geographical production regions: anywhere in the US for bourbon and five Mexican states for tequila
  • They have rules setting the ingredients: at least 51% corn for bourbon and at least 51% blue agave for tequila

However, there are some differences when it comes to aging. All bourbon must be barrel aged whereas tequila can be sold either aged or unaged.

Aging Process for Tequila Versus Bourbon

Barrel sourceCan be new or reused, e.g. from barrels that have previously held bourbon, wine or brandy.Must be new
Barrel woodOakOak
Wood treatmentCharred or toastedCharred
Barrel sizeTypically 53-59 gallons.If añejo or extra añejo, maximum size 600 liters (158.5 gallons)No rule, but typically 53 gallons (200 liters)
TimeframeDepends on the class of tequila:
Blanco: less than 2 months
Reposado: 2-12 months
Añejo: 12 months – 3 years
Extra añejo: 3+ years
Technically no set minimum, but must have an age statement if less than 4 years. Straight bourbon whiskey must be aged at least 2 years. Most bourbon is aged at least 4 years.
AdditivesRules permit additives up to 1%:
Caramel color
Oak extract
No additives permitted
LabelingNo requirement to state exact age but must state which age category (reposado, añejo etc.). If a blend of ages, the category is based on the youngest age.If aged less than 4 years, must be labeled with age statement. If a blend of ages, must state the youngest age.
VerificationAll barrels are sealed and checked by compliance officers. Seals can only be removed by officers.Lower level of regulatory supervision.

Key Differences in Tequila Versus Bourbon Aging:

  • Bourbon must be aged in new barrels, tequila is more often aged in barrels that have previously been used for aging other beverages such as bourbon or wine. This means Bourbon will only take on flavors from the wood itself, while tequila can take on flavors left over from whatever was last in the barrel. New barrels also give off more toffee and vanilla flavors which are less obvious in reused barrels. 
  • Most bourbon is aged much longer than tequila. While there’s no minimum age for bourbon, most popular brands of bourbon are aged for at least four years.
  • Bourbon needs aging to taste good, tequila can be perfectly enjoyable without any aging. Aging tequila is more a matter of taste and not a requirement. However some poorer quality tequilas use aging to smooth over unpleasant or more neutral spirit harshness.
  • Cristalino bourbon is not a thing. In recent years cristalino tequilas have gained popularity. The method involves filtering aged tequila through activated charcoal which produces a clear, colorless liquid. While many charcoal filtered bourbons exist, the process is done before barrel aging.
  • Tequila can have additives, bourbon cannot. In theory, the idea of allowing these additives is to replicate the aging process and produce a more mellow tequila. These additives do not have to be disclosed if they are under 1%, even if the bottle says 100% agave. The additives permitted by tequila regulators are:
    • Caramel color (appearance only, looks more aged)
    • Glycerine (adds a thicker mouthfeel, smoother)
    • Sweetener (can mellow the overall flavor, appeal to a wider rage of people)
    • Oak extract (can mellow the taste)
  • The different geographical weather systems will also affect the aging process.
    • Higher temperatures expand the spirit so that more goes into the wood fibers. As the temperature drops the spirit flows back into the barrel, bringing with it all of the compounds from the wood. At colder temperatures, not much happens at all.
    • Higher humidity means that alcohol is more likely to evaporate from the barrels, meaning the proof goes down over time. Lower humidity means water is more likely to be evaporated, meaning the proof goes up over time.
    • Looking at the respective production capitals (Bardstown, Kentucky for bourbon and Tequila, Jalisco for tequila), Bardstown has a higher temperature variation across the year compared to Tequila, but a lower daily temperature variation. Tequila on the other hand is a lot warmer for most of the year. Tequila has a much drier climate than Bardstown.

Average high/low temperature of Tequila and Bardstown

Chance of Muggy Conditions in Tequila and Bardstown (dew point above 65 ℉)

Climate data from weatherspark.com

Why Age Tequila and Bourbon?

Spirits aged in wood transform to take on flavor, aroma, color and texture. In the case of bourbon, it can’t be called bourbon if it hasn’t been aged. The overall effect can add balance, smoothness and complexity.

Unaged tequila can be complex and flavorful due to the profile of the agave itself. Unaged whiskey, and young bourbon has a lot less character, and is more harsh tasting. Bourbon is aged because it almost always gets better – tequila is aged either so bad quality tequila tastes better or good quality tequila tastes different.

Wood flavors can balance out the harsher alcohol flavors. The charing of the wood caramelizes the sugars in the wood fibers. After longer aging, flavors such as oak, vanilla, coffee, tobacco, dark chocolate and leather are noted. The aroma profile can be similar to the taste profile as the two senses are very linked. Tequila producers are allowed to use oak extract to imitate this effect, bourbon producers are not.

Spirits will first take on a golden, then darker brown color when in contact with wood. The same compounds which are responsible for the color will also add to the taste. In tequila, caramel coloring additives are sometimes used to make the liquid appear more aged than it is. While caramel coloring is permitted for making Scotch whisky, no additives are allowed for bourbon. 

Lastly, aging tequila and bourbon can result in a smoother, thicker texture which can feel slightly oily. Some tequila producers use glycerine as an additive to increase this effect.

Is There Unaged Bourbon?

By regulation bourbon must be aged, even if just for a few hours as there’s technically no minimum. Unaged bourbon would not be allowed to be called bourbon, and could just be called whiskey. Unaged whiskey is known as white whiskey, or informally as white dog, and may also be considered moonshine.

Other Facts About Aging Tequila and Bourbon:

  • Ex bourbon barrels are the most common for aging tequila. Because of bourbon’s requirement for new barrels, the industry is a large supplier of affordable used barrels.
  • Used barrels may be rejuvenated for tequila aging, by scraping off the inner wood layer and re-charring.
  • Smaller barrels will impart the effects of aging much quicker than larger barrels as more tequila can be exposed to the wood.
  • The name of a 600 liter barrel is a demi-muid, which is the maximum size for producing añejo tequila.
  • A barrel maker is called a cooper.
  • Barrels can be toasted to different levels. Higher toasted barrels will impart more flavors of vanilla, coffee and spice.
  • Other beverages frequently aged in oak include whiskey, rum, brandy, cognac, armagnac, calvados, sherry, port, wine, beer and cider.
  • The largest barrel producer in the world is Independent State Company, located in Lebanon, Missouri.

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