Aging Tequila

02. Introduction to Wood Science

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There are 2 primary species preferred for cask-making in tequila: Quercus alba or American white oak and Quercus petrea or European white oak. Each species offers slightly different flavor profiles. Additionally, the climate where the oak grows also affects flavors. So for example, spirits aged in Quercus petrea from Allier, France will taste different from spirits aged in Quercus petrea from the Zemplen Mountains forest in Hungary.

The major distinguishable physical difference between oak species is their density. European oak tends to be more dense (closer spaced rings) which impart less oak lactones and oxygen than American oak. Generally speaking, both American oak and European oak are ideal for aging tequila, because the spirit does well handling American oak’s robust flavors and oxygen ingress (when oxygen dissolves in the liquid over time, also known as oxidation), while at the same time aging in European oak imparts more delicate, spicy and fruity flavors.

A close up of a Patrón barrel, stacked amongst other barrels. The Patrón logo stamped on the barrel is in focus.

BARRELS — Añejo and extra añejo tequilas must be aged in barrels – the majority of which come from the Bourbon industry, who, by law, can only use them once. 

Flavor Compounds from Oak

How oak and its toast level introduce flavors into tequila varies by cooperage house style and producer specifications. A handful of compounds play the dominant roles in what flavors a barrel imparts to tequila. Each reacts to heat.

CIS- AND TRANS-OAK LACTONES

woody or coconut flavors

FURFURAL

dried fruit, burned almonds, burnt sugar, sweetness, light caramel flavors

EUGENOL

spices, cloves and smoke character

GUAIACOL

Burn overtones

OAK LACTONE

woody, dill and coconut notes

VANILLIN

vanilla

SYRINGALDEHYDE

vanilla-like