The Manufacturing of Mezcal and other Spirits from Agave

The manufacturing of traditional mezcal will be explained here first, as it is the origin of all agave spirits. In addition, we will mention the changes over time that have made industrial mass production possible. This is mainly used for internationally available tequila brands, but this does not mean that industrially produced spirits of other categories do not exist. In contrast, artisanal manufacturing of tequila has become very rare.

The manufacturing of traditional mezcal is certainly one of the most fascinating activities in the spirits business. The techniques used and their mastery are - without exaggeration - ancient art, passed down through generations within the mezcalero families. No control instruments or chemical additives are used here. Everything is based on selected raw materials, experience and feeling.

In our SHOP you will only find artisan brandies from family distilleries, without the use of additives or other "tricks".

Details on cultivation and harvesting on the page RAW MATERIAL AGAVE.

This process breaks down long-chain carbohydrates (inulin), which the plant stores as nutrients, into short-chain, fermentable sugars (fructose). To do this, pits are dug in which stones are piled over burning hardwood to heat them. Once the wood has burnt down and the stones are red hot, the maestro mezcalero lays out the agaves over and around the pile of stones in the pit until it is filled and covered with a mound of these plant parts. A layer of damp agave fibres over the hot stones protects the piñas from burning. In some areas, however, such as Jalisco, ovens are used that resemble a free-standing bread oven with a dome in form and function.

The mound is now covered with a cloth, tarpaulin, palm or banana leaves to prevent the subsequently applied soil from contaminating the agaves. This layer, together with the 30 cm layer of earth, seals the pile airtight. The remaining oxygen burns off, the remaining fire goes out and evaporating moisture causes a slight increase in pressure inside.

The flesh of the agave is now soft and has a brown colour. It smells sweetish, freshly of plant juices and slightly of caramel. There are also notes of wood, smoke and earth due to the treatment in the earth oven. This technique has been known for several thousand years in Mesoamerica.

For the further process, usually the whole plants are processed, but in rare cases only the juice is extracted by pressing and this is fermented. This is also the case in industrial production, as pure liquid substances are easier to handle in an industrial distillery.

Since the introduction of steam power and the machines available for steam generation (caldera), this technique has been rivalled by masonry ovens (hornos). Hot steam is blown into hermetically sealed rooms filled with agaves. This creates pressure and cooks the plants more efficiently than earth pits. Moreover, no smoky flavour remains in the final product.

The latest development is the diffuser, a machine originally developed for making agave syrup. It allows an almost 100% yield of agave sugar and shortens the process of converting starch to a minimum. Green agave is shredded and the inulin is washed out of the fibre under high pressure. This "syrup" is then saccharified by heating and adding acids and enzymes. However, this also creates undesirable flavours in the final product. The diffuser allows the processing of very young, unripe agaves, which produce a "flat" distillate. This is often remedied with additives. With the spread of the diffuser, the standard of the DO Tequila was also "adapted" and the regulation for processing "fully ripe agaves" was shortened to merely "agaves".

This ARTICLE by Adam Fodor illustrates the use of diffusers and is excellent.

In preparation for fermentation, unusable parts of the plant are first sorted out. These are usually overcooked or undercooked parts. The good pieces are then ground into a fibrous pulpy mixture (molienda). This is usually done by an upright mill wheel (tahona, molino egipcio or molino chileno), moved by draft animals (sometimes a machine), which is guided in a circle around a central axle. The wheel runs in a low basin in which the agaves lie. A person always walks in a circle with the draft animal to pull the material in the basin under the millstone.

However, other types of grinding are also used. More anciently, and in low-output distilleries, the agave hearts are crushed with wooden hammers (mazo) or pounders in stone or wooden basins (canoa). Some distillers have small choppers, especially in Oaxaca, where Agave karwinskii is processed, which is still very hard after the cooking process. Whether the type of grinding has a significant influence on the taste is disputed even among distillers.

In larger distilleries, agave is processed in roller mills, where the cooked material is crushed and pressed out onto metal rollers. In the diffuser, cooking and grinding are the same process. In both cases, the juice is separated from the solids.

The plant pulp resulting from the milling process is now mashed. Different vessels can be used for fermentation (fermentación), depending on tradition and local availability:

Over time, autochthonous strands emerge that are adapted to the processes on site and produce a specific flavour profile for each distillery. Thus, the concept of terroir is applicable not only to the location of the plant, but also to the distillery.

Some distilleries use must from the previous fermentation process as a starter for the new batch. In some areas, pulque, i.e. fermented agave juice, is also added. Cultured yeast is not used in traditional mezcal. Depending on the size of the vessels, the outside temperature, humidity and the agaves used, the fermentación takes between a few days and up to two weeks in cool weather.

Once fermentation is complete, i.e. all usable sugars have been broken down into alcohol by yeasts, the mash is distilled. It now has around 5% alcohol. The must be distilled within one day, otherwise it will spoil. Therefore, in a traditional distillery, the size of the pit oven, the capacity of the fermentation tanks and that of the stills are coordinated and the result is a batch (or lot) that usually does not exceed a few hundred liters.

In contrast to the traditional approach, only the liquid parts are fermented in industrial production, not the solids, i.e. fibres. These produce a more complex flavour, but also a higher methanol content. Liquid substances can easily be transported through pipes by pump in large-scale plants. They are inoculated with pure-breeding yeasts and fermented as quickly and efficiently as possible at a controlled temperature. The aim is to achieve the highest possible alcohol content (yield) and a consistent flavour profile. Chemicals are often used to control or accelerate fermentation, e.g. sulphuric acid. Unfortunately, this is also the case with some traditional distillers in spontaneous fermentation. This allows them to offer a cheaper mezcal. Chemical-free production is in fact purely a matter of trust, as it is difficult to trace in the final product.

Usually stills made of copper (alambique) are used, but sometimes also those that are made entirely or partly of ceramic pots (ollas) or plant parts (reeds, agave shoots, bamboo, wood). All these types do not allow continuous distillation, i.e. a filling is completely burnt off before the still is opened again and refilled. The most common is the copper still with a pot (olla, cucúrbita, retorta), helmet (cabezote, montera, capitel), spirit pipe (turbante, pasa-vapores) and snake cooler in a water bath (serpentín, culebra). There is no amplifier.

The manufacturing of mezcal from Santa Catarina Minas or Sola de Vega is done by a still made of clay and reeds, called alambique filipino or hornalla, among others, with internal condensation. This method is still used in some other places in Oaxaca. The still is an amphora-shaped clay vessel, which is built into a body of adobe bricks flush with the upper edge and is fired with wood from below. A round clay vessel (resollano) is placed on top of it, which has openings of about 20 cm at the top and bottom. A copper bowl (cazo) is placed on the upper opening, which contains the cooling water. The condensate forms on the curved underside of the bowl, falls into a wooden spoon (paleta) and is led through reeds (bitoque) through an opening in the montera to the outside into a collecting container. Fires distilled in ceramics tend to be 'denser' and more oily than those distilled in copper.

All modern methods of distillation are used. The classical method of copper pot stills makes up the greater part of the quality product, but large distilleries use continuous distillation and sometimes gigantic column stills made of stainless steel, which usually produce less expressive spirits.