Tequila comes from the fermentation and distillation of blue agave sap mixed with water. According to Mexican law, only liquor produced from Jalisco, Guanajuato, Michoacan, Mayarit and Tamaulipas that includes at least 51 percent agave juice qualifies as true tequila. Premium tequilas reach 80 proof, but aged varieties can attain higher alcohol levels. The highest-proof tequilas are 110- to 120-proof tequilas produced in pot stills in Mexico.
Cooking and Fermentation
Tequila producers harvest long, sword-shaped agave leaves when the plant matures, then cook them in pressure cookers or steam ovens to break the starches down into sugars. Tequila producers extract the juice from the cooked pulp for fermentation. During fermentation, the liquid goes into vessels, where it transforms into alcohol with an initial alcohol content ranging from 4 percent to 7 percent. In the case of mixtos, which are tequilas that contain less than 100-percent blue agave juice, additional sugars are added to the agave and water mixture before the liquid transfers to the vessels for fermentation.
Distillation and Aging
The fermented agave product undergoes a two-fold distillation process. The first distillation stage removes unwanted alcohol byproducts and impurities, resulting in a compound that is 25 percent alcohol by volume. The second distillation stage concentrates the alcohol to about 55 to 60 percent ABV, or 110 to 120 proof, in three hours. The cooled liquor then is run through a condenser and filtered for additional impurities, where it can reach 75 to 80 percent ABV, or 150 to 160 proof. Finally, water is added to the liquor to dilute it to the desired proof. Storage in wooden casks or wooden barrels for the aging process can elevate the alcohol content.
Tequila traces its origins back nearly 2,000 years, when the Aztecs found fermented agave creates a mildly alcoholic drink. When the Spanish arrived in Mexico, they discovered Mezcal tequila pulp with 3 percent ABV. The Spanish cooked down the pulp and distilled the liquid, increasing the alcohol content. Until the 1930s, tequila was produced from 100 percent agave nectar, but after that period, mixto became the predominant variety.
Comparison to Other Liquors
Tequila can range in alcohol content from 32 proof to 120 proof. Premium-quality tequilas are bottled at 80 proof, and when compared to other types of liquor, tequila lies in the middle of the spectrum. Cask-strength malt scotches are 120 proof, and bourbons and rums run the gamut from 100 to 108 proof. In general, any liquor bottled at 100 proof is considered a quality spirit.
The Mythical Worm
The worm of legend associated with tequila bottles usually appears only in Mezcal, a cousin of tequila made with a different type of agave. Known as tequila con gusano, or tequila with worms, the worm actually consists of larvae that live in the agave plant. It is believed the worm grants strength to those who have the nerve to swallow it. One theory hypothesizes the worm communicates the quality of the tequila. Thus, high-quality tequila allows pickled larva to remain perfectly intact.
- Tastings: All About Tequila and Mezcal
- The Deluxe Food Lover's Companion; Sharon Tyler Herbst and Ron Herbst
- In Search of the Blue Agave: An Introduction to the Spirits of the Blue Agave
- The Washington Post: Spirits: Understanding Alcohol Proof
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