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Bottoms Up with Joe Micallef

Understanding Tequila: Mexico’s Gift to the World


Joe Micallef

Wine and spirits judge, historian and bestselling author. Apart from dealing with sobering world affairs, Joe has been an entertaining educator of wines and spirits and judges at major spirits competitions. He has tasted a range that we could only dream of – from centuries-old ports, Cognacs to many of the world’s oldest whiskies. He also writes on Forbes, The Epoch Times and comments on international politics. Follow Joe on Forbes or his website.



(All photos are credited to Joseph Micallef) 


Tequila is deeply interwoven in the culture and history of Mexico. Along with bourbon, it is one of only two spirits which are indigenous to the Americas. Both spirits are based on plants which evolved in North America and where found exclusively there. Corn in the case of bourbon and agave in the case of tequila. Indeed, a case can be made that tequila is the only true authentically North American spirit since notwithstanding the predominance of corn; bourbon’s mash bills typically include a significant amount of wheat, barley and sometimes rye. All three of which originated in Eurasia.

There are roughly 200 species of agave in the Americas. Their natural habitat is a zone that ranges from the Great Plains and deserts of the United States to the tropical jungles of South America. For the most part, however, they inhabit arid zones, typically at altitudes of between 2,000 and 7,000 feet above sea level. Since its discovery, agave has spread all over the world both as an ornamental plant and as an agricultural crop. It was widely cultivated for example in South Africa’s Great Karoo Desert to produce agave sugar and syrup.

The highlands of central Mexico host about 150 different varieties of agave, roughly 75% of all known varieties. Agave hybridizes readily with related species. It’s not always clear which varieties of agave are unique species and which are hybrids, so a definitive count of the number of agave species remains elusive. It is likely that the highlands of Central Mexico are the region where the agave evolved, what botanists refer to as the zone of genetic diversity. Not surprisingly, this same zone is also the center of tequila and mescal production.

Long before there was tequila there was agave. The plant was deeply entwined in the myth and lore of native American cultures; from the Navajo in the southwestern US to the Aztecs of central Mexico. Agave was nothing short of a miracle plant. Its sap was highly nutritious and the piña, the heart of the agave plant, when cooked, was an important source of carbohydrates. A cooked piña tastes like sweet potato or yam. Its leaves were a source of fiber and thatch and could be woven into a variety of containers. Its spines were used as needles. The plant was considered nothing less than a gift from the gods and figured prominently in native religious ritual.

One of the most desirable byproducts of the agave was its sap. Historically, it was collected in much the same way that maple trees are tapped for their sweet sap and consumed as a calorie rich, nutritious food. The usual method was to expose the top of the piña and partially hollow it out. The sap would collect in the depression. The sweet sap, called agua miel or honey water, could also be fermented to produce a sweet, beer like drink called pulque. The consumption of both agua miel and pulque are pre-Columbian in origin and date back deep into the recesses of Mexican antiquity. 

It is likely that the first primitive forms of agave based distillates emerged sometime during the 16th century. Exports from Spain to the new world were highly taxed. Combined with the transportation costs, that meant that imports in the Spanish colonies would routinely cost ten times their cost in Spain. Not surprisingly, there was a great deal of interest in finding a local, inexpensive source of alcohol.

Spanish colonists refereed to agave based distillates as mescal or mescal wine. The term mescal was a corruption of the Amerindian word for agave, maguey. Initially, a wide variety of agave would have been used, a tradition that continues to this day for mescal production. Technically, any agave based distillate is a mescal. Tequila is a kind of mescal produced from one specific variety of agave, the blue agave or Agave angustifolia subsp. tequilana var. Weber Azul.

By law only distillates made from this variety of agave and which are produced in in the state of Jalisco and in a specific delineated area in the states of Nayarit, Michoacán, Guanajuato and Tamaulipas can be called tequila. From a practical standpoint, more than 90% of Mexican tequila production occurs within a 50-mile radius of the town of Tequila in Jalisco state.


The red soils of the highlands of Jalisco. The Tequila Volcano is in the background.


The tequila producing region itself is divided into lowlands and highlands. The distinction is a relative one, the lowlands are at an elevation of around 4,000 feet above sea level while the highlands are at elevations of 7,000 feet or more. The highlands are characterized by red volcanic soils of decomposed basaltic lava. Highland agaves are larger, juicier, and mature more slowly. They are also subject to more diurnal temperature variation. They tend to produce tequilas with more distinct sweeter, floral and fruitier notes.

Lowland agaves are grown in soils that are richer and darker but have less mineral content than highland soils. The weather in the lowlands is drier, harsher and with less temperature variation between night and day. The agaves here are smaller, rounder, and are characterized by more earthy, vegetal, herbal, peppery and woody flavors.

There are any number of agave varieties that can be used to make an alcoholic distillate. Mexico is awash with regional spirits based on one or more local varieties of agave. Like tequila, these would be considered subcategories of mescal. Sotol, for example, is produced in Chihuahua, Durango and Coahuila. It is based on fermenting and distilling the sap of the Desert Spoon (Dasylirion wheeleri), an agave-like plant. Bacanora is produced in Sonora from the wild Agave Pacifica (Agave angustofolia). Raicilla, on the other hand is produced primarily in Puerto Vallarta and seven other communities in Jalisco state. It is based on Agave Lechuguilla (Agave inaequidens) and Agave Pata de Mula (Agave maximiliana). Every state in Mexico has a local agave based distillate that is produced from one or more of the indigenous agave in that region.

Mexico’s second largest agave based distillate, referred to simply as mescal, is made primarily in Oaxaca using some 30 different varieties of agaves, although 90% of the production is from a variety of agave called Espadin (Agave angustofolia var. haw). Espadin is widely believed to be one of the genetic parents of the blue agave variety used in tequila production. There are seven other Mexican states besides Oaxaca, however, that can also produce an agave based distillate that can be called mescal. About six million liters of mescal were produced in 2016, a fraction of the 272 million liters of tequila produced that year.

The process for producing tequila is relatively straightforward and consists of 4 basic steps: converting the starch, inulin, in the piña to fermentable sugars, fermentation, distillation and maturation. While the process appears to be relatively straight forward, there is an enormous amount of possible variations in how each of those steps are carried out.

Historically, the inulin, a type of complex starch, in the agave piñas would be broken down into useable sugars by cooking it. This is the same process that converts starches in potatoes of squash into simpler, digestible sugars. Before the late 19th century, the piñaswould have been cooked in rock lined fire pits that had been heated with a wood fire. This is still the technique used by many mescal producers, hence the characteristic smoky aroma associated with mescal.


Piñas ready to be cooked at Casa Herradura.


Stone ovens or hornos were introduced in the second half of the 19th century, mostly because rising tequila production in Jalisco was denuding the local forests. Heated with gas or coal also had the advantage of being far more efficient and of standardizing the cooking process. Ovens were typically made of brick and lined with clay. The piñas would usually be baked for a period of 2 to 3 days at moderate heat, 140 to 185 degrees F. Lower temperatures tend to prevent caramelization of the agave while still breaking up the long starch molecules into short, fermentable sugars leaving more sugar for the yeast to convert into alcohol. This process also reduces the bitter flavors associated with caramelized or burnt sugars.

In the second half of the 20th century hornos were supplemented by stainless steel autoclaves. These are essentially giant pressure cookers that cook the agave with a combination of heat and high pressure steam. Autoclaves have the advantage of cooking the piñasin 12 to 18 hours. Both hornos and autoclaves use steam to cook the agave, the difference is that an autoclave can use higher pressures, basically the difference between cooking in a pot and a pressure cooker.

A third method, the diffuser method, extracts the inulin from the shredded piñas using hot water or steam and then cooks the resulting juice, or mosto, to breakdown the complex starches into fermentable sugars. Sauza uses a diffuser method in the production of its tequilas, a process it likens to seeping tea. Rather than first cooking the piña, a diffuser sprays hot water over the shredded piñas to dissolve and extract the starches.

The diffuser process takes approximately four hours. The resulting, starch laden liquid is then cooked in an autoclave for about three hours at a temperature of 248 degrees F. Diffusers can extract up to 99% of the usable inulin in the piña. The result is a far more efficient production process. Whereas it generally takes 7 kgs. of piñas to make one liter of tequila, a diffuser can extract enough inulin from 5 kgs. to make the same amount of tequila.

Once the piñas have been cooked the juice is separated from the fibers. The traditional way of doing this was with a tahona, a large circular milling stone that was pulled around a circular stone pit by a pack animal. The tahona would crush the fibers extracting the juice which would then be collected and moved to a fermenter. A modern version of the same process is to use a multi-stage rolling mill that first shreds then squeezes the fibers to extract the juice. Most distilleries have a high-speed shredder followed by five sets of rolling mills.

Diffusers can also be used to extract any remaining sugars from the cooked piñas. In this case, as the starches have already been broken down, hot water is sprayed on the shredded, cooked piñas to extract the last bit of fermentable sugar. The resulting liquid along with the juice that was extracted by the rollers is collected and sent directly to the fermenter.

Different distillers use different techniques to cook and extract the inulin from the piñas. Combined with the specific cooking temperature regime, the different extraction methods will produce different taste and aroma profiles. In some cases, some producers will use several methods in order to add more complexity and nuance to the resulting distillate.


Baked piñas in a stone oven at Casa Herradura.


Herradura, Don Julio and Avion for example use traditional stone ovens and a shredder and rolling mills to extract the juice from the piñas. Cazadores uses steam autoclaves exclusively followed by a shredder and rolling mill. Patron uses stone ovens and a tahona to mill their piñas while Sauza uses diffusers to extract the inulin and then cooks or hydrolyzes it to produce a fermentable mosto.

Fermentation can be equally complex. Don Julio, Cazadores, Sauza and Patron all have proprietary yeast strains that were isolated by the distillery from wild yeasts. In Don Julio’s case, that occurred 42 years ago and they have continued to use the same yeast. Herradura on the other hand uses naturally occurring wild yeast to ferment their mosto. Other distillers use a combination of commercial yeasts, including ones that are used for commercial wine production, sparkling wines or brewing.

Some distillers, like Cazadores, will also allow a secondary, bacterial, malolactic fermentation in their mosto. Finally, distillers can opt to use the pulp or bagasse that remains after the piñas have been shredded and squeezed in the fermenters. Patron for example, will use bagasse in half of their fermenters. The bagasse forms a cap that reduces evaporation from the fermenters and helps to retain some of the more volatile esters responsible for fruity and floral aromas.

Distillation involves either pot or column stills. Traditionally, pot stills are made of copper since copper absorbs or scavenges sulfurous compounds in the distillate that are produced during fermentation. Patron’s stills are all made of copper. Other distillers use steel stills that are either lined with copper inside or have copper strips hanging inside them to duplicate the effect of a copper still. Most tequila producers use copper lined steel stills as these are less expensive and last longer.


Copper still at the Patron Tequila distillery. The different shaped stills create a broader range of aromas and tastes.


Many distillers use a combination of pot stills and continuous or column stills. Column stills have the advantage of being cheaper to operate and generally produce a lighter, more refined distillate, ideal for unaged tequilas. Column stills can also be twinned with a hydro-selector column to reduce the amount of methanol in a distillate. Agave piñas are prone to produce higher levels of methanol than cereal based distillates. Although the higher level is still within safety limits, they can run afoul of safety regulations in those countries, like China, that have set acceptable methanol levels at a low threshold.

Typically, low priced tequilas, especially mixtos will rely primarily or exclusively on column still distillation while ultra-premium brands are usually based on a double pot still distillation. Lately there has been a trend towards triple, quadruple and even quintuple pot still distilling among tequila producers. Everything else is usually a combination of the two distillation processes with the amount of pot still produced spirit rising in proportion to the final selling price.

The final step in tequila production is maturation. Historically, tequila did not undergo long maturations. The delicate flavor of the agave distillate was deemed unsuitable for prolonged contact with oak barrels. This has now changed in two important respects. First extended maturation is now the norm. Whereas, 20 years ago a tequila aged more than a year was the exception, today every major tequila producer offers an extra añejo tequila that has been aged for at least 3 years and as much as 5 years.

Secondly, maturation strategies are becoming much more sophisticated. Historically, if tequila was aged it would be in ex-bourbon barrels of American White oak (Quercus alba) since these were the cheapest barrels available. Today super-premium tequila producers are using a variety of barrel woods including finishing aged tequila in barrels that previously held sherry or port wines as well as barrels that have held other spirits like rum or cognac.

In addition, new oak barrels are being judiciously used for brief periods on a portion of the distillate to create a broader range of flavors. The combination of using multiple types of casks adds a greater degree of nuance and subtlety to the matured tequila. Herradura has a port cask finished tequila and Patron has done the same with a sherry cask finish. Both are superb but difficult to find as the demand greatly exceeds the supply. Patron, it’s rumored, also has a port cask finished tequila in the works but it has not yet been announced.

The production of tequila has become far more sophisticated than is generally understood. The production process, while relatively straight forward offers artisan distillers a wide palette from which to shape their final product. In the process, the beverage itself has become far more nuanced and complex, offering expressions that can compete handily with the finest rums, Cognacs and whiskies of the world. Tequila may never leave behind the oceans of margaritas and salt and lime shot-fests, but it has become much more sophisticated than its humble origins would have promised.


By Joseph V. Micallef

Joseph V. Micallef is a judge and commentator on food, wines, spirits and travel. He is also a historian, best-selling author, keynote speaker and syndicated columnist As a journalist and former war correspondent he has written on an eclectic mix of topics from wines, spirits and travel, to military history and world affairs. For 30+ years he was the CEO and Senior Producer of a media company. 

Joe has also been a judge for a variety of international wines and spirits competitions, including the International Wines and Spirits Competition, World Drinks Awards, World Whisky Awards, San Francisco International Wine Competition, American Distilling Institute Craft Spirits Awards, and the Irish Whiskey Awards. Along with judging, he spends his spare time making wine in Oregon.

He holds the Diploma in Wines and Spirits from the Wine and Spirits Education Trust (London). He is also a member of the Advisory Board of the Council of Whiskey Masters. The Advisory Board’s two dozen members are widely considered the leading experts on whisky in the world.

He has spoken at a variety of professional venues, including the Institute of Strategic Studies (London), the NATO Defense College (Rome), the World Future Society and a large number of universities, military and other organizations on a variety of topics dealing with military and current affairs. He has also appeared as a commentator on a variety of cable news networks.

His recent books include, Scotch Whisky: It’s History, Production and Appreciation, Understanding World War I: A Concise History (part of a 12 episode made for television documentary), and Islamic State: Its History, Ideology and Challenge. Additional books on Tequila and on Italian Wines are forthcoming.

He has written, directed, and produced dozens of documentaries on military history and current affairs.

Joe is also an opinion columnist for The Epoch Times where he writes about national security and international affairs, and a contributor to Forbes where he writes about wines, spirits and travel to the dusty corners of the world. In addition to writing, he is also the International Editor for the Irish Whiskey Magazine.

He has spent more than 20 years judging wines and spirits and lecturing and writing about them, and looks forward to many more. Grab a drink with him at the bar if you have the chance – suffice to say, he's not your average Joe.