Agave for tequila grows for seven to eight years before it can be harvested. Not until then are the starches in the agave concentrated and developed enough to be converted to the rich, flavorful sugars that make a good tequila. The plants in this field are one year old.
This agave field was recently harvested. Some farmers let fields go fallow for a year before replanting. After harvesting, any leaves, stalks, and roots remaining in Olmeca's field are shredded and tilled into the soil, and the field is planted with corn or another crop for two years, only returning to agave production in the third year.
The fields are not irrigated; when I asked about this, Jesús Hernandez told me that some farmers have tried irrigation, but the plants get green without developing the complex starches that are necessary. He said in most years, natural rainfall is sufficient. The distillery grows about 60% of its agave, and buys the other 40%.
The industry is growing faster than planting, so although at present, there's still an oversupply of agave, most producers fear another agave shortage like the one that hit the industry in 2000. Some producers, therefore, are harvesting early, after six years rather than seven. "They're robbing from future years," Hernandez warns. The starch concentration in the hearts isn't as high as it should be, he says, so producers need more agave to make their tequila, and this extends the shortage even more.
A Pile of Piñas
The piña is the harvested heart of the agave. Once they're gathered from the field, they're trucked here, to the reception area of the distillery. Workers use a tool similar to a long-handled hoe to pick them up from the floor and deposit them onto conveyers.
Piñas Entering the Oven
The starches in agave hearts need to be converted to sugars prior to fermentation. Tequila makers have several ways to do this. Olmeca uses large ovens to roast agaves. The agave hearts are steam-roasted in a large oven for 36 hours at 200° Fahrenheit. Agave syrup is collected from the floor of the oven. Later in the process, the distillers will use this syrup to propagate the cultivated yeast strain that Olmeca uses for all its tequilas.
Many distilleries today use autoclaves, or pressure cookers, to steam-blast the agaves. Although this process is more efficient than using an oven, it tends to scorch the sugars, making for smoky and bitter flavors. Some of the largest distilleries now use diffusers, instead of either ovens or autoclaves, to extract the juices from the agave hearts without cooking them. This is the most efficient and cost-effective process for extracting sugars from the agaves, but many believe it sacrifices the flavors you'd get by cooking the agave fibers.
The yeast at Olmeca is descended from a wild yeast originally found in the agave itself. Some distilleries use wild yeasts for the fermentation process, but Hernandez finds that these processes are too unpredictable.
Roasted Agaves Exit the Oven
The temperature at this spot inside the distillery is only mildly warm, despite being so close to the ovens. The distillery smells a little like roasted figs, dates, or sweet potatoes. Though I didn't get a photo of it, the distillery offered us a small piece of roasted agave. The flavor is pleasant and mildly sweet.
From here, the hearts go either to the tahona mill or to the roller mill. Want to see 'em?
The Tahona Mill
The tahona is a huge two-ton stone made of volcanic rock. A spare stone sits outside on the distillery grounds as decoration, but the distillers can use it if the main stone becomes cracked. (It takes four months to make a new stone, so not having a spare would be very costly for the distillery.)
Though formerly mules and horses pulled tahonas, a machine now does the work of pulling the stone around and around. A man stands inside the milling floor, raking the agave fibers into place in the path of the millstone.
The Roller Mill
A stainless-steel roller mill shreds the agave into fibers, spraying water over the top to help extract the the sugars. The liquid is collected below the mill and fed via pipes into fermentation tanks. The fiber from the rolling mill is collected for reuse in the distillery's compost piles.
Mosto entering a fermentation tank. Mosto is a "soup" of agave juices mixed with the yeast-syrup mixture I mentioned earlier.
Peering in the Fermentation Tank
Fermenting mosto. We climbed up a set of steel stairs to get to the top of the fermentation tanks. The temperature was very hot, and the air up there definitely smelled of a low-alcohol fermented beverage, somewhat like hot cider or warm beer.
Drains in the floor of the tank pull the fermented mosto out, by gravity, to a pump, which sends the mosto up a tall pipe and into one of several copper-pot stills.
We we weren't allowed to take photos from much closer than this vantage point, for fear of sparking a fire and explosion. (All that alcohol vapor in the air...)
Mosto from the tahona is loaded into a still along with the fibers, which add flavor in distillation. Mosto from the roller mill is pumped into the stills without any fiber. The final distillates are blended together before aging, in proportions that Hernandez keeps close to the vest.
The distillery has these long compost piles, made from the fibers from the roller mills, other solid wastes from production, and wastewater from distillation. Machinery lays down the solid wastes first, and then another machine trickles in the wastewater, gently turning it into the piles to avoid water runoff. The compost is used as natural fertilizer for the agave fields, supplementing the chemical fertilizers that Olmeca also uses. They estimate that composting reduces fertilizer costs by 30%.
Bottling the Tequila
Olmeca's tequilas are aged onsite at the distillery in a large warehouse. The Plata rests in stainless steel tanks for 30 days before bottling. The Reposado is aged 7 to 8 months (the legal requirement is a minimum of 2 months).
After aging, the tequila is pumped by hand into glass bottles. The bottles are capped and sealed, and then labeled, before being sealed up into cases for shipping.
A line of empty bottles await filling.