Certified mezcal is defined and classified by a Norma Oficial Mexicana (NOM) on mezcal. Per the Norm and tradition alike, all mezcal is 100% agave/maguey – no other sugar source may be added during fermentation. The Norm establishes three categories of mezcal, which are broken down further into six classes.
The first category is referred to by some critics as “industrial mezcal,” since it allows for modern production methods imported from the tequila industry. At the extreme, these mezcals can be produced by cooking the agave in autoclaves, extracting the juice with a diffuser, and distilling in a stainless-steel column.
The second is Artisanal mezcal: The vast majority of certified mezcal falls into this category. The use of autoclaves, diffusers, and column stills is prohibited. A typical artisanal process is described below (in “Mezcal Production”).
The third one is Ancestral mezcal: In this category, the maguey must be pit-cooked and mallet-crushed or stone-milled. Distillation must be in clay pots, and stainless steel is prohibited.
Types of Mezcal
White: Unaged and unadulterated, the vast majority of mezcal falls into this class.
“Matured in glass” : mezcal stored in glass for over twelve months, underground or somewhere with minimal variation in light, temperature, and humidity. Storing in glass (especially buried underground) is a traditional practice that softens the mezcal over time, without lowering the alcohol content.
Mezcal “rested” in a wood vessel of any type or size, for between two and 12 months.
Mezcal aged in any type of wooden vessel of less than 1000 liters for more than a year.
Flavored or infused mezcal. The Norm specifically permits maguey “worms,” damiana, lime, orange, mango, and honey. Other fruits, herbs, and caramel are also common additions.
“Distilled with” – otherwise known as mezcales de pechuga. In this traditional process, a second or third distillation is done with other ingredients in the still itself. These may include regional fruits, meat, herbs, etc.