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.
Cooking and Steaming, Traditional
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 kiln now rests for three to five days to ensure a slow transformation process; rarely is it kept sealed longer. Once the cooking process is complete, the oven is dismantled and the piñas are stored in a clean and dry place in preparation for the meal. This storage time is important as it breaks down cellulose and facilitates the subsequent milling and fermentation process. Therefore, the storage time depends on the type of agave and varies according to local customs. Mould or insect infestation is nothing unusual, but sometimes even desirable.
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.
Cooking and Steaming, Modern
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.
In the Tequila world, this method is now considered traditional, as there are already some even more modern and efficient techniques. This is the autoclave, an industrial pressure cooker made of stainless steel, comparable in shape and size to the tank of a tanker truck. This enables cooking under controlled supply of steam, pressure and temperature. This shortens cooking considerably at high settings, but can also be run on low. Both produce very different results, similar to preparing food.
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:
Hollowed tree trunks, tubs made of natural or masonry stone, cow skins, clay pots and many others, but usually large wooden barrels (tinas) are used. All vessels are handled unsealed to ensure the access of natural yeasts that cause the spontaneous fermentation process. These and other microbes are found on fermentation tanks, tools and all objects in the distillery and are reproduced during each fermentation process.
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.
The end of fermentation is determined by the fading noise inside the vessel, the shape of the openings in the fibrous pulp floating on top (caused by escaping CO²), the smell, the temperature of the mash and the taste of a sample taken at different heights of the vessel. Each agave variety produces recognisable differences in the mash and has different fermentation times.
Karwinskii varieties, for example, tend to ferment more sourly, while Espadín (A. angustifolia) is sweetish.
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.
Distillers in the Jalisco and Michoacan regions (e.g. DON MATEO and MEZONTE) work in a similar way, although different materials are used here. While the actual pot containing the mash is made of copper, the upper part is made of wood. In the case of small distilleries, this is made of a hollow tree trunk; in the case of larger distilleries, it is made of barrel staves. On top of these, in turn, sits a metal pan as a condenser. Distillers with internal condensation were brought to Mexico around 1600 by Filipino slaves to distil palm wine (tuba). These very simple alambics are still in use in Asia today.
Mezcal is distilled twice, in rare cases (e.g. Pechuga) three times. Normally, the solids, i.e. the fibres (bagazo), are added to the still during the first distillation, so the separation from the must takes place during the first distillation. In a few areas, only the liquid must is processed.
1. distillation, wash distillation: the still is filled in equal parts with the liquid components and the fibres from the fermentation tanks. During the distillation process, the wash (ordinario, común, shishe) is produced with an alcohol content of 10 to 40%, depending on the type of agave.
2. distillation, spirit distillation: The second pass (rectificación) produces the heads (puntas, cabezas), body (cuerpo, corazón) and the tails (cola). The body is consumed at the strength it comes out of the still -about 45% to 60% by volume- , adjusted with the other fractions or diluted with water.
This is the procedure in Oaxaca when using copper pot stills. On the other hand, in Santa Catarina Minas (at REAL MINERO), when ceramic stills are used, four fractions are separated: punta (heads, 59-80% by volume), cuerpo (body, 50-60% by volume), cola (tails, 10-20% by volume) and inguishe (no further information).
At DON MATEO in Michoacan (copper & wood pot still), five fractions are known: flor (58-70% vol), mezcal floreado (53-58% vol), mezcalito (44-53% vol), fuertes (20-44% vol) and colas (-20% vol).
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.
Product Control, Traditional
The product is controlled during distillation by dropping a small amount of liquid in a jet-like manner into a vessel, usually from a reed (venencia) into a calabash (jícara). During this process, bubbles (perlas, perlado) form, which give the master distiller information about specific qualities, mainly the alcohol content.
The bubbles should form a circle and, if possible, a closed ring around the edge of the bowl (cordón de perlas) and then cover the surface. In some areas, drinking horns or other vessels are also used for these tests. The master distiller also massages the distillate into the palms of his hands from time to time and smells it to pick up consistency and scents. Beyond that, a distillery has no measuring or control instruments of any kind, except for the experience of its maestro mezcalero.
Product Control, Modern
Physico-chemical controls are required and carried out as part of the standard by DO regulatory bodies (CRM, CRT etc). Samples are taken at each step of the process and before bottling the final product is checked in certified laboratories. It must be mentioned that Tequila and the far more profoundly tested Mezcal have an exceptionally high level of product safety, as every single batch is tested before bottling. In Europe, there is no routine for product control of spirits.
The different production methods naturally produce different products. More on this on the next page under TYPES & QUALITIES.
Taste Tequila shows how much the processing methods influence the taste by means of the ratings of products by its followers.