Tequila production begins with the jima (harvest) of Agave plants that are either "estate grown" (grown by the producer), purchased from other growers, or a combination of the two. The blue Agave takes 8-12 years before it reaches harvest maturity, when a yellow hue appears on leaves in the interior of the plant.The jimador (harvester) uses traditional hand tools, as used over the last 100 years, to cut apart the Agave. The spiny leaves are first sheared from the plants in order to expose the "heart" of the Agave, commonly called the cabeza (head) or piña, because it resembles a giant pineapple. The roots are then cut, and the plant is removed from the earth. The Agave is trimmed until only the "piña" remains. The Agave "hearts" can weigh 80-175 lbs each. They are loaded onto trucks and hauled off to the distillery.
At the distillery, the "hearts" are halved or quartered. They are then packed into brick or concrete ovens for cooking. Steam is injected into the ovens and the Agave is cooked for 24-36 hours. The "pines" are allowed to cool for 24 hours before they are removed from the oven. Juices released from the Agave during the cooking process are collected at the bottom of the oven and put into special containers. This juice is known as "agua miel" (honey water). Cooking converts the plant's starches into sugars.
The milling process extracts additional juices from the cooked Agave. A milling or juicing machine, or in some cases a stone grinding wheel (Tahona), is used to crush the Agave and press out the remaining juices. The juice (Must) is then put into holding containers.
The juices (must) produced by the "milling" process are put into fermentation tanks or vessels. Yeasts are added to the juice to begin the conversion of sugars into alcohol. The fermentation process can take between 5 and 10 days under "natural" conditions. Some producers use additives to speed up fermentation.
The fermented Agave juice is next put into the stills. Mexican law requires that tequila be distilled at least twice. In distillation, the juices are heated up in order to vaporize the alcohol. The vaporized alcohol is carried off into a cooling condenser. The first and last portions of the alcohol are regarded as impure and are discarded. The remaining product, known as "ordinario," is 20-30% alcohol at this stage.The distillate of the Agave is then distilled again, often in a second still, and produces the resulting product: tequila. After distilling for a second time, the tequila has an alcohol content of 40% (80 proof). Certain premium tequilas are "triple distilled" in order to produce a purer product.
Tequila that will be used to make a "Reposado" (rested) or "Anejo" (aged) product is typically aged in wooden tanks, barrels, or casks. Reposado tequila is commonly aged in larger wooden tanks that are often made of redwood. The "resting" of the tequila in the wooden vessels changes the color, flavor, and texture of it. Aging often imparts a quality of smoothness to the Reposado tequila.Tequilas that will become an añejo product are aged in used Kentucky bourbon barrels made of oak. Imported French white oak barrels are also used, especially in the production of premium tequilas. Barrels of varying ages can be selected and will determine the final character of the product. Newer barrels impart a stronger flavor and imbue the tequila with more color. Older barrels produce a smoother, less-colored product.