Producing Tequila

From Blue Agave to Noble Spirit.

Tequila is not produced from the typical grains or fruits that most alcoholic beverages are made from. It is distilled from the roasted centre (pina) of the blue agave plant - one of 136 species of agave that grow in Mexico (with 26 sub-species, 29 varieties and 7 types). The blue agave was first classified by German botanist F. Weber in 1905, hence its technical name "agave tequilana weber azul".  It has a lifespan of 8-14 years, depending on soil, climate and cultivation methods and is actually related to the lily and amaryllis (it has its own genus, "Agave" -  from the Greek word for 'noble.') It is known as a succulent and although it shares a common habitat with many cacti, it is not one itself. The Agave plant looks like an unripe, oversized pineapple or spiked cactus which shoots a giant blossom that can take up to twelve years to produce. At maturity, it stands about 1.5 metres high and is bluish green in colour depending upon the species, growing conditions and climate. The agave used in mezcal, although similar, is harvested younger than the tequila agave.

Most of Jalisco state where tequila is made is a high plateau that averages 2,800 metres above sea level, with sandy, mineral-rich red soil in the highlands, and black earth in the valleys. It is a mountainous, hilly region - but agave grows best above 1,500 metres. According to some, the best agave plants grow on the slopes of the extinct volcano beside the town. Others consider the highlands to the east to be superior because highland agave tend to grow larger, such as the Arandas agave, which consequently commands  higher prices.  The discrepency may be due to the fact that highland distillers tend to use more traditional production methods to manufacture smaller quantities of tequila, while the modern metropolitan distillers focus on export product - usually mixto tequila (an inferior product made with sugars added to the fermenting agave to increase the alcohol content).

Apart from Jalisco, Blue agave for tequila production may  be grown in the states of Nayarit, Guanajuato and Michoacan. The agave plants are grown in cultivated orchards called 'potreros' (pastures, also called campos de agave, huertas, or groves in the Los Altos region). Traditional plantings may still have corn and beans growing between the rows. There can be anywhere from 1,000 to 2,000 plants/acre.

Agaves are propogated from shoots (mecuates or hijuleos) taken from the adult plants at the start if the rainy season in their fourth to sixth year (when the shoots themselves are at least a year old, and about the size of a leek or small onion). The shoots are left in the fields to dry out for about a month before they are planted in a nursery for another year [right], after which they are transferred to the fields. Sometimes the shoots are planted right away, just before the rainy season, so they can get established in the soil more quickly. The agave may also be grown from seed, although this is generally not done any more.

The part of the plant that is used for tequila is the heart (root), or pina (also called the head, or cabeza), which looks like a large pineapple or pinecone. It starts underground, but soon pushes its way into the light. A mature pina usually weighs 35 to 140 kg although most are under 90 kilograms. Pinas weighing  230kg have been cultivated in the highlands, though the occurrence is rare. The agave plant takes at least eight years to reach the stage where it is suitable for fermentation and may be left for up to 12 years before harvesting; the more mature, the better its natural sugars. During this time it is pruned, cutting the points of the leaves with machetes to encourage the pina to grow. Some farmers also use a technique called 'shotgun plowing' to induce premature ripening of plants, but most fields are hand grown and cultivated, using traditional methods. Modern producers often spray agave fields with fertilizers and pesticides. Most use farm hands to meticulously control the weeds by hand. Fields are not irrigated; the plants depend entirely on the rainy season for moisture. Experiments with irrigation have shown that while larger plants result,  agave sugars levels do not increase.

Left to grow in the wild,  pinas extend a tall shoot, 4.5+ metres high, with pale yellow flowers at the top. The wild flowers are pollinated by local long-nosed bats (Leptonycteris nivalis). After producing 3,000-5,000 seeds, the plants naturally die. The dwindling population of long nosed bats is an environmental concern which may spell serious trouble in the future for wild agaves used for fibre, pulque and mezcal. The young, tender flower stalk is called a quiote or quixotl, and is picked and eaten as a vegetable. The stalk is not allowed to grow on cultivated agaves, because it uses up the nutrients in the plant to produce its seeds, and is cut so the pina grows fatter. The pina is ripe when it starts to shrink and develops a maroon tinge with red spots appearing on the leaves.

When ready for harvesting, the carbohydrate-rich pina is cut from its stalk. Then the 200 or more spiky and thorn-covered leaves (pencas) that stand out from the agave are cut away from the heart by a jimador (from the Nahuatl word 'jima', meaning 'harvest'). The Jimador uses a sharp, long-handled tool called a coa. This procedure is illustrated below.

The skill of harvesting is passed down from father to son and some fields have three generations of jimadors working in them. Methodical, but efficient, a good jimador can harvest more than a ton of pinas in a day. Full truck loads are carried to the factory  where the pinas are usually quartered or halved before baking. Harvesting is done year-round because the plants mature at different stages in the fields. Some large distillers pick young agaves, but others, like Herradura, use only plants 10 years or older.

Some distillers will 'pre-cook' the pinas to rid them of external waxes and solids that may be retained in the penca. These can make a bitter or unpleasant juice. The steam-injected autoclaves (oversized pressure cookers) used in modern distilleries also wash away any external materials from the pinas. Farmers who sell pinas by weight may leave on more of the leaves, while those paid daily wages by the producer are more likely to cut them off closer to the pina. It takes about 7 kilograms of pina to produce 1 litre of 100% agave tequila - which means the average pina can make 60-100 litres. Traditional distillers (tequilleros) let the pinas soften in steam rooms or slow-bake ovens for 50-72 hours [pictured right]. The traditional stone or brick oven is called a horno - hence the name of Sauza's Hornitos Tequila. This bakes the agave to process its natural juices at around 60-80 degrees celsius. This slow-bake process softens the fibres and helps keep the agave from caramelizing, which adds bitter flavours to the juice and reduces the agave sugars. Baking in ovens also helps retain more of the natural agave flavours.  Here's where mezcal and tequila part ways: mezcal pinas are baked slowly in underground pits, rather than steamed. Many large distillers prefer to cook their pinas faster in efficient steam pressure cookers in as little as a single day (8-14 hours). The baking process turns the complex carbohydrates into fermentable sugars and softens the pina so they can easily release their juice. Fresh from the oven, the pinas taste a bit like a sweet potato or yam, with a mild tequila aftertaste. In traditional distilleries, the pinas are allowed to cool for another 24-36 hours after steaming, then they are mashed to separate the pulp (bagazo or bagasse) from the juice although some traditional distillers keep them together during the fermenting. Small distillers may simply purchase agave syrup to ferment, without any of the intervening processes.

Originally, manufacturers beat the pinas with mallets to break them up once they were soft and cool. Then they moved to the tahona, a giant grinding wheel weighing up to two tons, operated by mules, oxen or horses (nowadays more likely by a tractor, pictured right). Modern distilleries use a mechanical crusher, or shredder, like a giant wood-chipping machine to process out the waste  (usually given away as animal food or fertilizer). By these methods, the pinas are minced and strained to remove the juices (called aquamiel, or honey water), then mixed with water in large vats.

The resulting wort  is sprinkled with yeast. Traditionally this is a yeast that grows naturally on the leaves of the plant, but today it may be a cultivated form or even a commercial brewer's yeast. Natural fermentation from airborne yeasts is sometimes allowed in some traditional mezcals. (E.g. - Tequila Herradura). 

The must is left to ferment in wooden or stainless steel tanks [pictured right]. This can naturally take seven to twelve days, but todays producers can add chemicals to accelerate yeast growth so fermentation only takes two to three days. Longer fermentation results in a more full bodied Tequila. Fermented must may also be used as a starter mixture for the next batch. Sometimes the must is fermented with the residual pulp from the pinas left in it to impart the most flavour to the liquid - another traditional practice - but more often the pulp is disposed of. It may be sold to construction firms for adding to bricks or as packing material. Some manufacturers use cane or brown sugar cones (piloncillo) to speed fermentation which enables the use of immature and fewer agaves. This type of tequila can be sold in bulk for export, and can be bottled in other countries where the regulations regarding agave content are not necessarily maintained. These tequilas are called mixto, and can not be labelled 100% agave. After fermentation is finished, the must may be left another twelve hours to richen and settle before distillation.

The result of fermentation is a liquid with about 5-7% alcohol/volume. Distillation takes four to eight hours usually in traditional copper pot stills called alambiques, or in modern stainless-steel column stills. The first distillation taking 1 1/2-2 hours is called the ordinario and is about 20% Alc./Vol. The second distillation takes 3-4 hours and results in approximately 55% Alc./Vol. Like all spirit distillations, there are three components: the cabeza, or head, has more alcohol and unwanted aldehydes, so it is discarded. The middle section is the El corazon, the heart, which is the best part and saved for production. The end is the colos, or tails, which is sometimes recycled into the next distillation to make it more robust, or else discarded. One premium blend , Profidio, is exclusive in offering a triple-distilled product, however some connoisseurs believe it comes with a subsequent loss of flavour.

All tequila is clear after distillation. The colour comes later, from aging in wooden barrels or from additives like caramel (used in mixto tequilas only) or wood essence. Reposado and anejo tequilas will be stored in barrels generally purchased from American distillers (x-bourbon barrels are the most prized but some distillers use x-sherry barrels, whiskey barrels, cognac barrels and even new oak  to impart sharper flavours). Old barrels, up  to 50 or 60 years of age may still be in use. Barrels are stored in warehouses or bodegas. Only blanco (white tequila) will remain in stainless steel tanks until bottling or may be bottled immediately after distillation.

The colour of a tequila does not necessarily reflect either age or quality. The passion for premium aged tequilas that look like brandies has led some distillers to extend maturation periods in order to absorb the maximum colouring. Others simply add colouring to create the impression of age, which may also affect the flavour. 

The final product is usually blended with other barrels of a similar age to create a consistency of taste and aroma. Before bottling, most tequila is filtered through activated carbon or cellulose filters and most distillers add de-mineralized water to bring the alcoholic strength down to 80 (40% Alc./Vol.). Representatives of the Tequila Regulatory Council oversee the production to ensure the distillers meet the standards and quality controls in place under Mexican legislation.  All 100% agave tequilas must be bottled in Mexico and marked "Hecho en Mexico" - made in Mexico. Only mixto tequila is allowed to be sold in bulk and bottled outside the country. 

Today, tequila production is facing a crisis - the combined result of a plague of diseases and pests with spiraling agave costs and an agave shortage. This shortage has seen several distillers drop their low-end brands in favour of higher-priced premium products. The shortage could also seriously impact mezcal producers because tequila manufacturers are already buying agave from Oaxaca state to shore up their dwindling supplies. Mezcal producers face a 40% increase in costs due to the demand by tequila manufacturers for the agaves from Oaxaca. This appears to violate the Mexican regulations and standards for tequila production but the industry seems remarkably quiet in the face of it.