Brush up your agave knowledge with Happy Gilmour

Words by Alex 'Happy' Gilmour

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Sydney's own tequila expert, currently running the tiny mezcaleria that is Cantina OK, breaks down what you need to know about how tequila is made.

Let's take a minute to talk about production. There has been a lot of vocal comparison between production methods when dealing with agave spirits, and almost every producer believes that their methods produce the best tequila for their tastes. So here is the breakdown:

The Denomination of Origin

Both tequila and mezcal have registered denominations of origin. These outline regions in México where each can be produced. For tequila, the five states of Jalisco, Nayarit, Tamaulipas, Guanajuato, and Michoacán are the limits for both growing the plant and for production of all 100% agave tequila.

Mezcal now has nine states protected by law and these include Oaxaca, Guerrero, Tamaulipas, Michoacán, Durango, Puebla, Zacatecas, San Luis Potosi, and Guanajuato.

Bonus fact: There is historical evidence of fermentation and distillation of agave in at least 22 of the 31 states of México, which includes products like bacanora from the northern states of Sonora and raicilla from Jalisco.

The Plant

Agave takes longer to mature than most other raw materials used to produce alcohol across the globe. Agave tequilana used for tequila production takes between six and 12 years to fully mature, and it's at this point where the plant is ready to flower and begin sexual reproduction.

Once the plant has fully matured it will grow a quiote from its center, which looks like a tall branch or stem that towers above the agave and eventually flowers. This quiote needs to be cut off before it becomes fully grown to ensure that enough sugars are kept in the base of the plant for spirit production. If the quiote is allowed to grow to full height too much energy and sugars are drawn from the heart of the agave and it can't be used to make alcohol. Little hijuelos will develop on the side of many agaves after the plant reaches about three years of age. These rhizomes are clones of the mother plant and can be harvested and then replanted for growth into fully matured plants.

Not all agaves will produce rhizomes and will have to rely on the growth of the quiote and the temperament of the harvesters to allow it to flower and be pollinated by the local wildlife. It is more common in the world of mezcal to see mezcaleros leave some of the silvestre (wild) agave to flower, as this is the only way to ensure there will be some in the future. Many wild agaves mature at much slower rates, and at a much lower yield than those that are cultivated, with species like Agave marmorata - commonly known as tepeztate - taking between 18 and 25 years to mature and in very specific microclimates. Similarly Agave cupreata - also known as papalometl - has a very specific area within México where its common and naturally occurring, on average this variety will take over 15 years to reach maturity.

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Harvest

To date there is still no better method to harvest agave than men and sharp tools. Be it using the coa, which is the prized tool of the jimadores of tequila, or using machetes and axes like the rest of México, trained professionals can make short work of the sturdy and spikey agave. The aim is to strip the plant of its leaves, whittling it down to its core or heart known as a piña. In cultivated agave fields the harvest is a systematic approach by a team of men who are there working long hours to load the piñas of the agave into a truck to be taken to the distillery. In the case of the wild agaves, the harvested plants are loaded onto the back of donkeys and horses to be brought out of the wilderness before being loaded onto utes and taken to the distillery.

Roasting

One of the most noticeable differences between the taste of tequila and mezcal is the traditional and pronounced smoky taste of the latter. This flavour becomes imparted in the cooking or roasting process, whereas tequila is traditionally steam cooked. Historically this is undertaken by loading the harvested and cut piñas into stone/brick ovens and sealing them up to have steam fed in through pipes underneath. Standard roast times using brick ovens are around 24-36 hours. More modern distilleries are using autoclaves, which are essentially large, usually cylindrical, pressure vessels which also use steam to cook the agave but have the ability to subject the raw agaves to pressures up to 10 atmospheres which can reduce cooking times down to 7-10 hours.

Traditional mezcal production roasts the harvested agave in wood-fired ovens. The styles vary from state-to-state and producer-to-producer but there are two common styles:
1. The most common is the big pit ovens which are dug deep into the ground, big bonfires are built and stoked for at least 12 hours to ensure the volume of hot coals is large enough. Then the fire is covered by spent agave fibers before being loaded up with harvested agave. The used fibers protect the harvested agave from having direct contact with the coals and overburning. The harvested agave is stacked up into a big mound and then covered with tarpaulin and soil to keep the heat in which has the effect of forcing the smoke from the fire to permeate the agaves as they are cooking and gives mezcal that distinctive taste.
2. The other method is using the clay adobe ovens. This is where large clay ovens, similar to traditional pizza ovens, are built with pits beneath them to hold the fires. The ovens are loaded up with the harvested agave and sealed to ensure the concentration of heat doesn’t escape.

A word on diffusors: There is an advanced roasting method which has gained a lot of press around both tequila and mezcal production – this is the use of diffusors to strip out almost all of the useable sugars and starches, making them the most efficient method of agave roasting. However, the fact that they can remove up to 99% of starch from the fibers of the plant also means that the oils and acids that leave bitter flavours in the juice remain. Diffusors work by shredding the un-cooked agave while blasting the fibers with boiling water; these fibers and juices are then subjected to extreme pressures, and sometimes sulphuric acids, to leave a dry, exhausted pulp. The juices are then boiled to hydrolise them and activate the fermentable sugars.

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Crushing

Once the agave has been roasted it needs to cool down before it can be crushed to separate the sweet juices from the fibrous agave. Prior to roasting I really wouldn’t recommend trying to bite into a piece of agave but after, ohhh the juicy flavours are fantastic!

Traditional crushing methods were very rudimentary. A couple of guys with a hollowed-out rock or tree trunk and then bashing the cooked age pieces with wooden mallets. The agave would be bashed until the fibers had begun to separate enough that the juices were being pressed out and partially reabsorbed. This is the most laborious method of traditional agave distillate production and not as common in settings where larger volumes are being manufactured.

Large stone wheels called tahonas are used in many mezcal palenques and some tequila fabricas. They are drawn around in a stone-lined pit and crush the agave to a fibrous mash. This is a more efficient way than hand crushing the agave and because the tahona stones tend to way about 2-2.5 ton each, they are able to get the fibers to a much finer consistency than hand crushing with a mallet. In some instances, large wood chippers are used pre-tahona to speed up the crushing process. This method doesn’t change the flavour, in my opinion, it just allows for more manageable pieces to be crushed at a much higher speed.

In many tequila houses, a roller mill is used to crush the roasted agave and separate the juices from the fiber. The roasted piñas are loaded on to a conveyor belt, which passes them through a series of mechanical shredders and presses to extract all the juice. As the agave passes through the shredders and presses, hot water is fed over the agave to assist in the extraction of juice. On a normal roller mill, the agave will pass through three or four crushings before the spent fiber is discarded.

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Fermentation

Fermentation is the action of sugar being eaten by yeast to produce ethanol and carbon dioxide. In mezcal production the fibers are removed by hand from the crushing area and placed into big bins or barrels, most commonly made from wood but also from stone or earthen pits. In some cases, untreated animal hide is used to hold the bagazo or fibers. Then hot and cold water is added to fill the vats. Over the next three to seven days the indigenous wild yeasts will start to develop within the tank and begin fermentation. In traditional mezcal production the water is the only thing added to the agave after crushing.

In most tequila production the fibers have had most of their useable fermented sugars pressed out and fermentation may take place in either stainless steel or wooden vats. The pressed juices are pumped into these vats and proprietary yeasts are added at a very specific ratio to produce an agave like beer. In most cases the agave fibers are not included with the wash to ferment, however some of the tahona-crushed tequilas are fermented with their fibers.

Distillation

To be called tequila the product must be distilled a minimum of two times, in either copper or stainless stills. These stills range from smaller 150-250 liter pot stills to larger stills that range up to the thousand-liter mark. There are also distilleries using multiple plate column stills, which are usually made from stainless steel. Copper is a favorable material for pot still construction as with most other distillates, as copper will react with the vapors during distillation and removes the taste of sulphur leftover from the dead yeast. The first distillation of a tequila is called ordinario and the second is called tequila.

Mezcal distillation is interesting as legally they are only bound to a single distillation before it can be called mezcal. While there are many distilleries using copper pot stills, they are all on the smaller end of the spectrum with most around the 200-liter average volume. Mezcal producers are also know for using more traditional artisanal stills which tend to be handmade clay stills and clay stills with wooden chambers. Before you ask what is the common size of the clay base of a pot still, the common answer is the length of a Mexican lady’s arm. In truth, because these stills are handmade, they need to be replaced regularly.

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Ageing

Sourcing barrels to age spirits is usually a task focused around convenience and taste profile. For tequila, most barrels have come down from bourbon producers in the USA and then used repeatedly to age and store. Blanco tequila cannot have spent any longer than 60 days in contact with wood. Reposados will have spent between two months to just less than a year in oak barrels. Finally, añejo is aged between one and three years in oak barrels that are 600-liters or less. The newest category is the extra-añejos, which are aged for greater than three years in oak barrels of 600-liters or less.

This is the area of production that has the most noticeable difference between tequila and mezcal. Where tequila is usually sold in categories of age, most mezcal being consumed is focused on the variety of agave and sold un-aged and at still strength. The rules surrounding mezcal do permit ageing, and there are some amazing aged mezcals on the market, but they aren't as common. It also should be noted that there are definitely some mezcals that are aged in glass, where they rest away from direct light in glass demijohns.

So this is what I call a brief drop into agave distillates in México. I know there is a lot of information to digest and now even more questions to ask, but this is the point of chasing education. With it, we arm ourselves to educate others. If you ever have any questions about this please don’t hesitate to hit me up. I love to talk about this for hours!

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