Mezcal is distilled from a variety of Agave types. It must be distilled at least two times. Agaves harvested in the valley region have a more herbaceous fragrance and flavor.
Production
Harvesting is largely done manually. The stalks (quiotes) are regularly trimmed, preventing flowering and allowing ripening. The leaves are cut and the succulent cores (piñas) are slowly baked to break down fructans into fructose. The piñas are cooked for about three days, often in pit ovens, which are earthen mounds over pits of hot rocks. This underground roasting gives mezcal its intense and distinctive smoky flavor. They are then mashed and fermented in vats/barrels with water and distilled (twice) in clay/copper pots.
Joven is barely aged or not aged at all. Dorado has coloring added. Reposado/añejado is aged 2-9 months and añejo is aged at least 12 months.
Varieties
Mezcal can be made from around 50 varieties.
Espadín: The most common making up almost 90% of all Mezcal. It has high inulin (a carbohydrate), is less fibrous and breaks down easier. The plant matures much faster, in 6 to 8 years.
Tobalá: A rare varietal found in Southern Mexico. It takes 10 to 15 years to mature and has low inulin content resulting in earthy, fruity mezcals.
Arroqueño: Another rare varietal that takes up to 25 years to mature. It makes a floral mezcal with "green" notes.
Cenizo: Common in Durango and grows at high altitudes. The flavor varies depending on where it is grown.
Tepeztate: Takes up to 25 years to mature and produces an intensely flavored mezcal with strong spice notes.
Agave Karwinskii: Has many varietals that tend to produce herbal, mineral mezcals with a "chalky" taste.