Most people who enjoy margaritas and similarly made cocktails are familiar with tequila. Yet, the extensive range of this proud Mexican spirit is often underappreciated. While "blanco" or silver and "resposado" tequilas are consumed in the majority of margaritas or downed with salt and lime, many fans of the spirit have not experienced the joy of sipping "anejo" tequila.

As a recent article in Sante magazine points out, anejo is best understood in the context of the other two categories of tequila. Blanco, or silver, tequilas are clean and fresh with little or no oak aging, and they showcase the fresh agave fruit qualities that make them so compatible with lime juice in the margarita.

Reposado or "rested" tequilas are aged for at least two months in oak barrels, which rounds off the spirit and adds subtle nuances of oak. Reposado tequila can offer a stronger flavor to margaritas, function as a base spirit in other cocktails, or be enjoyed neat.

Anejo tequilas are a different thing entirely. Aged in oak for a minimum of 12 months, these spirits are much more oak-dominated and can range from slightly smoky to strongly toasty. The mellowing of the spirit by slow aging in oak promotes an impressive complexity of flavors and produces a spirit that is ideal for pure and unadulterated sipping.

Extended aging melds oak flavor with the clean flavors of the agave, resulting in a truly unique beverage. Plus, because each anejo undergoes its own distilling and aging regimens, each product is as distinctive as a single-malt Scotch.

Once tequila is made, determining how to age it is the choice of the tequila master—and there are numerous options. Producers in the lowlands areas such as Jalisco tend to use a higher percentage of new oak than producers in the highlands regions such as Los Altos.

Just as with wine, the more times a barrel is used, the less oak flavor and oak tannin it will impart to the spirit. In addition, the type of oak used can offer significant flavor differences. Although the tradition has been to use old bourbon or whiskey barrels, there has recently been much experimentation with French oak, including used burgundy barrels.

Anejo tequila has the further specification that it must not be aged in oak barrels larger than 600 liters in capacity. This regulation ensures that there is a distinctive oak flavor in the spirit and adds a consistency to the category.

However, even with this rule in place, there is considerable variation among producers in the time anejos spend in oak barrels before release and the type of barrels used. Centinela uses nothing larger than 180-liter barrels for aging. El Tesoro prefers extended aging and keeps its anjesos for two to three years in underground cellars. El Charro ages its reposado tequila in bourbon barrels and its anejo in French oak.

Jose Cuervo typically uses barrel from Kentucky as well as new French Limousin Cognac barrels. Jose Cuervo’s Reserva de la Familia bottling has an average of seven to ten years of age in new wood, while its 1800 reserve anejo is aged with a larger proportion of American oak.

Clearly, the time a spirit spends aging in oak adds cost to the final product. Not only are there the costs of space, barrels and inventory, but evaporation losses can be significant.

According to industry data, a typical distillery will produce 70 to 80 percent reposado and five to 10 percent each of blanco/silver and anejo. The aging regimen is strictly monitored by laws governing tequila production, which, in turn, help make anejo tequila one of the world’s most complex and expensive spirits.

Keep in mind that there is a wide diversity of brands and styles of anejo tequila. As you taste different super-premium products, look for nuance and complexity of flavors that lend a certain character and uniqueness.

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