OK, let's get right down to it. At what point does lengthy aging in used barrels turn tequila into something that, while perhaps still an excellent product, no longer is tequila?

I've been posing that question to various people in the tequila field for the past year as more and more distillers introduce aged spirits that have been matured in anything from used bourbon barrels to cognac casks to wine barrels. The latest discussion was with Carlos Camarena, third-generation head of Tequila Tapatia, which manufactures the El Tesoro line.

So far, the preponderance of opinion has been that we're seeing something that, while called tequila, really isn't since tequila is almost by definition a young spirit with the nose and palate punch of youth.

When you see people sampling a tequila in a brandy snifter instead of a traditional 2-ounce caballito — sort of an elongated shot glass — you know they aren't regarding it as run-of-the-mill tequila, be it 100 percent blue agave or mixto.

Riedel, the iconic Austrian glassware manufacturer, has come up with a tasting glass designed especially for anejo tequilas. Or, as is becoming a more common niche title, extra anejos.

The Riedel design comes in sets of four for a $35-$45 suggested retail price. In a real marketing coup, Riedel had its glass designated by the Consejo Regulador del Tequila (Regulating Council of the Tequila), the industry sanctioning body, as the first official tequila tasting glass ever made.

I asked Camarena if he agreed with the idea that extra-aged anejos are becoming a new spirit until themselves.

"To some extent, yes," he said during a celebratory dinner at his Arandas, Jalisco, facility marking its 70th anniversary.

"It certainly has changed the way you have to create and market your line since everyone is coming up with barrel-aged versions of their drinks. Now, we're paying a lot of attention to color and nose, things that didn't matter quite as much with blanco or reposada tequilas."

Is there, then, a specific point at which you should question whether the spirit still is tequila?

"If it has too much oak in it," Camarena quickly decreed.

Camarena and his staff came up with an extra anejo called Aniversario to mark its 70th birthday. It's a seven-year-old copper-colored tequila that was aged in charred American oak barrels. The final product is a blend of the best of the small batch.

"This is a one-shot. After this, there is no more," Camarena said.

Does that mean we'll see no more new additions to the El Tesoro line once the Aniversario is gone?

"Not at all," Camarena said. "We have some ideas we're working on, and we'll continue to come up with new limited edition aged tequilas as long as we can find a market for them."

Given that El Tesoro is part of the huge Beam Global Spirits & Wine organization, it's a safe bet finding markets to serve will continue. In addition to its public relations and marketing efforts, Beam's influence is seen in something as basic as the design of the Aniversario bottle.

Asked if the design was created by a local artist, Camarena said he didn't even know who did it except that it was a project handled at the corporate level.

Go to dowdtastingnotes.blogspot.com for my tasting notes on the El Tesoro line and a closeup look of the Aniversario bottle.)

In a visit to Tequila town several months earlier I spoke with Javier Orendain Lopez about the aging trend. The brand manager of Tequila Orendain de Jalisco told me, "It's a topic that is being discussed and debated more all the time.

"As distillers try to separate themselves from the competition they want to keep turning out new and different tequilas. So, many of them age them in different wooden barrels for different amounts of time. A lot of people are saying the taste is so different after long aging that even though the results can be wonderful they may not truly be tequila anymore."

(William M. Dowd covers food, drink and destinations at dowdsguides.com.)

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