Mezcal is a Mexican distilled spirit made from the agave plant, and refers to all agave based liquors that are not tequila. Its fabrication and consumption are closely associated with the Mexican State of Oaxaca.
Mezcal is made from the agave plant, commonly referred to in Mexico as maguey. In the tequila region the indigenous people call the plant mezcal. Agave — a Greek word meaning noble — was assigned to the 400 + species a hundred years ago due to the large number of uses that the plant offered ancient peoples. After the agave matures (6-8 years) it is harvested by magueyeros (agave field workers, more generally called jimadores) and the leaves are chopped off using a long-handled knife known as a coa or coa de jima (a type of machete), leaving only the large hearts, which are called corazón (Spanish for "heart") or piñas (Spanish for "pineapple"). The corazón is then cooked and crushed, producing a mash.
Baking and mashing
Traditionally, the piñas are baked in palenques: large (8-12 ft in diameter) rock-lined conical pits in the ground. A 3-4 foot cubic pile of trunk oak in the bottom of the pit is covered by rocks 6" in diameter and the wood is burned, turning the rocks red hot. Next the piñas are piled to 3-4 feet above ground level, then covered with banana leaves, used fiber from the last process, or agave leaves, then petate (palm fiber mats), and finally earth. The piñas are allowed to cook in the pit for three to five days. This converts the starches to fructose and lets the piñas absorb flavors from the earth and wood smoke coating the rocks.
After the cooking, the piñas are left to sit for a week, then placed in a ring of stone or concrete about 12 ft in diameter, where a large stone wheel attached to a post in the middle is pulled around by horse or burro, crushing the piñas.
Modern commercial makers cook the piñas with steam from a boiler in huge stainless steel ovens and then crush them with mechanical crushers.
The mash (tepache) is then placed in large, 300-500-gallon wooden vats and 5%–10% water is added to the mix. The government requires that 80% of this mix be from agave (as opposed to tequila which is less regulated at 51%). Cane and corn sugars may be added at this stage. In the case of smaller farmer distillers, it is left to naturally ferment for four to thirty days with the action of only airborne microbes. In the case of commercial producers, chemical accelerators like ammonium sulfate or Urea are allowed and quantity is not limited.
Distillation and aging
After the fermentation stage is done, the mash is double-distilled. The first distillation yields ordinary low-grade alcohol. After the first distillation, the fibers are removed from the still and the resulting alcohol from the first distillation added back into the still. This mixture is distilled once again. At this point the mezcal may be bottled or aged.
Mezcal ages quite rapidly in comparison to other spirits. It is aged in large wooden barrels for two months to seven years. During this time the mezcal acquires a golden color, and its flavor is influenced by the wooden barrels. The longer it is aged, the darker the color and the more noticeable the flavor.
- Añejo – Aged for at least a year in barrels no larger than 350 litres.
posado (rested) – Aged two months to a year.
- Joven (Blanco) – "Young" White (colorless) mezcal, aged less than two months.
Items added during bottling
A number of objects are frequently added into mezcal bottles along with the mezcal itself. These can include worms, scorpions, and decorative elements such as glass sculptures.
The "worm" (sometimes more than one) commonly seen in bottles of mezcal is actually the larvae of one of two kinds of insects. The most common type is the larvae of the agave snout weevil.   The "red worm" or gusano rojo is the caterpillar of the Hypopta agavis moth, one of the several kinds of "maguey worm". The worm is found on the agave plant. The originator of this practice was a man named Jacobo Lozano Páez. In 1940, while tasting prepared agave, he and his partner found that the worm changed the taste of the agave. (Agave worms are sometimes found in the piña after harvesting). Many brands contain such worms. Some are named after the worm itself, as in Gusano Rojo and some are even named for unusual use of a worm, e.g. Dos Gusanos, which uses two.
When a worm is included this is known as 'Con Gusano,' which means 'with worm.' Aside from its consumption with mezcal, the maguey worm is considered a delicacy in Mexico and can be found on some restaurant menus.
It is believed in certain traditions that doing this is beneficial to the spirit and locks in the vigour of mezcal.
The use of the worm is exclusive to mezcal, since the Mexican standards authority, NOM, prohibits adding insects or larvae to tequila.