Mezcal: the Three Categories

Mezcal production is rooted in the agave-rich landscapes of south-central Mexico, with the oldest continuous traditions in Oaxaca, though ancestral practice extends to Durango, Guerrero, San Luis Potosí, and beyond. The technology of distillation arrived in the colonial period; the agave itself, and the knowledge of cooking and fermenting it, is pre-Columbian, expressed before distillation in pulque and cooked agave hearts consumed as food.

Mezcal is any distilled spirit made from agave under Mexico's NOM-070 regulation, which governs production method, agave species, and geography. It is among the most ecologically and technically complex spirits in the world: the raw material grows for years or decades before it can be harvested, and the methods of cooking, fermenting, and distilling it range from ancient to modern. NOM-070 sets out three categories — mezcal, artesanal, and ancestral — that describe, in ascending order of traditional practice, how the spirit is made. The category appears on the label and is one of the few objective coordinates a buyer can use. The first category, simply called mezcal, permits the widest range of equipment. Cooking may be done in above-ground autoclaves; milling may be mechanical; fermentation may be in fibre or stainless tanks; distillation may be in copper or stainless-steel pot stills or column stills. The resulting spirit is still made from agave and must meet compositional standards, but the industrial latitude here is considerable. Most entry-level commercial mezcal falls into this category. The artesanal category tightens the parameters significantly. Cooking must take place in above-ground conical ovens (hornos) or pit ovens; milling may use a tahona (the large stone wheel drawn by horse, mule, or oxen), wooden mallets, or a roller mill — but not a diffuser. Fermentation must be in wooden, clay, or stone vats, or animal hides; open-air fermentation that captures wild yeasts is characteristic of this tier. Distillation must be in copper or clay pot stills. The traditional Oaxacan copper still with a wooden cooling hood — sometimes called the Filipino still, a shape introduced via trade contact — falls here. So does the refrescadera, a variant in which the distillate passes through a chamber filled with raw agave fibre and hearts, adding aromatic intensity. The ancestral category is the most restrictive and corresponds most closely to how mezcal has been made in isolated highland communities for centuries. Cooking is exclusively in a pit oven — the p'íib-like underground chamber lined with hot rocks, which chars and steams the agave hearts (piñas) simultaneously over several days. This smoking is the primary source of mezcal's signature char and earth. Milling must be by tahona or wooden mallet only. Fermentation is in animal hides or clay pots, often outdoors and open to ambient yeasts, bacteria, and temperature swings; a maestro mezcalero may add agave juice, water, or a portion of the previous batch's spent pulp (tepache-like backset) to start the culture. Distillation must be in a clay pot still, which gives a lower efficiency, a shorter cut, and a distinctly textured, sometimes waxy spirit. Tobalá (Agave potatorum), tepeztate (A. marmorata), mexicano (A. rhodacantha), and other non-espadin species are most often found in this category, though espadin (A. angustifolia) is produced ancestrally too. The species dimension is as important as the category. Espadín is Agave angustifolia, fast-growing and widely farmed; tobalá is A. potatorum, a smaller, slow-maturing wild or semi-cultivated plant of the high sierra. Wild-harvested agave adds pressure on natural populations, a genuine conservation concern that a literate drinker should carry. Some producers are propagating wild species in nurseries; others work exclusively with sustainably cultivated plants. Across all three categories, the denomination's states are currently the subject of ongoing regulatory dispute, so no definitive list is given here. What the three-tier system does not capture — and what the label cannot tell you — is the identity of the maestro mezcalero, the village, the harvest year, the specific wild-yeast population, or the precise maguey age. These details, where disclosed by the producer, are the real intelligence on a bottle. The denomination requires their disclosure increasingly, but practice is uneven. Mezcal is not a single flavour profile. It is a family of spirits unified by agave and shaped by every variable between the ground and the glass: species, altitude, soil, fermentation biology, fire, still geometry, and the judgement of the person making the cut. The three categories are a structural guide, not a hierarchy of quality — an ancestral mezcal can be poorly made, and a mezcal-category spirit can be excellent. They describe method, and method creates the conditions in which quality is possible.

The pit oven is the dominant flavour event in ancestral and many artesanal mezcals: the combination of steam and radiant heat from buried rocks over two to five days produces Maillard and caramelisation compounds in the agave's starches and fructans, yielding smoked-fruit, earth, leather, roast-vegetable, and mineral registers. Open-air fermentation adds lactic and acetic acids, wild-yeast esters — often tropical fruit, dried herbs, barnyard — and a living variation that changes with season and altitude. The clay pot still, being less efficient than copper, leaves more congeners in the spirit; the result is a heavier, sometimes waxy or lanolin-like body. Espadín tends toward green olive, smoke, and stone fruit; tobalá toward mineral, floral, and candied-citrus notes; tepeztate toward wilder, more herbaceous complexity. Proof matters: many ancestral mezcals are bottled at or near still strength, typically 46–55% ABV, which exaggerates all of the above in both senses — intensity and roughness — and demands that the drinker slow down.