Fermentation and Distillation
The agave juice is then fermented for several days in vats – usually made of stainless steel, though sometimes of wood. The temperature of the juice rises as yeast convert the sugar into alcohol. At this point, the concoction has an alcohol content similar to beer or wine, and this much of the process had been carried out in some form for millenia years by indigenous Mexicans prior to the Conquest.
The Spanish arrived not just with the cross and the sword, however, but with the copper pot still, which they had inherited from their former occupiers, the Arab Moors. Missing their brandy and fed up with high liquor taxes imposed by the Crown, the settlers soon began distilling fermented agave juice into what was later called mezcal wine, Mexican brandy or Mexican whiskey. Today, fermented agave juice is distilled at least twice, and the result, cut with water to bring it to the appropriate alcohol percentage, is tequila.