HOW TEQUILA IS MADE
Jalisco is one of the known towns in the Highlands of Mexico that is know to have soil that is volcanic in composition. The heavy concentration of minerals gives the soil a reddish tint. Weber species (Weber Blue Agave) thrives in this region. The ecosystem absorbs water when it rains thus no irrigation is necessary to farm the agave plants. Harvesting the agave plant remains a manual effort, unchanged by modern farming technologies, and stretching back hundreds of years. The agave is planted, tended, and harvested by hand. The men who harvest it, the "jimadors". The jimadors must be able to work swiftly in the tight rows, pull out the pups without damaging the mother plant, clear the piñas (Spanish word for pineapple), and decide when and if each plant is ready for harvest. There are three different methods used today to make tequila.

The first method used to make tequila is the "Artisanal Process" whereby the cooked agave is crushed by a large stone wheel called a "tahona" pulled by mule or ox. This process mostly uses machines like the stone-lined cooking ovens, wooden fermentation tanks, and steam copper pot stills.The second method is a more modern process where the cooked agave is crushed by mechanical roller shredding mills and presses. During the shredding process, the fibers are washed with water to help extract the sugars. This process uses a stainless steel autoclaves, stainless fermentation tanks, and stainless pot stills. And the third method used also is the "Diffuser Process" whereby uncooked 'piñas' are fed through mechanical shredders to break down the fibers. This involves raw extraction of the carbohydrates of the previously shredded piñas and their dilution in water, with the help of a diffuser. The product is then fed through an in-line cooker. This process uses the columnar stills. In most distilleries for making tequila, the method mostly used is method two. The piñas are slowly cooked in a steam room or traditional oven (called a horno) for about 1 to 2 days in less than 200 degrees Fahrenheit (90-95 C), the slow cooking process reduces caramelization which adds bitter flavor and reduces sugar while maintaining the natural agave flavor. The cooking breaks down the fibers and releases the natural juices.
Another process used long ago, but no longer used to make tequila today, involved cooking the agave piñas in underground pits lined with rock and clay. Similar to how a pig is roasted for a Hawaiian Luau, the natives would build a fire in a pit lined with rock and clay. They would let the fire burn down and then place the piñas on ambers and coals. They would then cover the piñas with agave leaves and soil and allow it to bake slowly for several hours. In those times they used below-ground fermentation pits and direct-fired copper stills. The tequila was stored in clay or glass containers with limited use of wooden tanks and barrels.
Another piece of equipment now being used by many distillers to cook the agave piñas is the autoclave. The autoclave acts as a huge pressure cooker. The autoclave method reduces the cooking time to about 18 hours. The idea is to cook the agave so that it can slowly convert the starch to sugar. Both the autoclave and horno ovens are heated with steam created by large steam generators known as "calderas". These calderas also provide steam to heat the pot stills and/or column stills for distillation. The cooked piñas are then air-cooled for 8-24 hours before entering the next stage of the process.
Once cooked, the piñas are transferred to shredders that extract the precious juices called "mosto". Water is introduced to the shredding process to help extract the sugars from the agave fibers. The mosto is then transferred to large fermentation vats. Yeast is added to accelerate the process of converting the sugars into alcohol.
The time required to complete fermentation takes about 3-10 days depending on the environment. It will take longer in the winter when temperatures are lower. Once fermentation is complete, the mosto is then left to settle for about 12 hours to richen. The fermentation yields a liquid with about 5-7% alcohol. This product is then normally double-distilled in traditional copper pot stills (called alambiques) or by use of modern stainless-steel column stills to increase its alcohol percentage and separate the desired volatile substances from the undesired ones.
The times required for each distillation varies between distillers. If the first distillation takes about 1½ to 2 hours it produces about 20% alcohol. If the second distillation takes 3 to 4 hours and yields about 55% alcohol content.

During distillation, the product develops into three components: the "cabeza", or head, has more alcohol and unwanted aldehydes (undesirable ethanol/methanol), 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 may also be discarded. The residue, or dregs ("vinazas") is discarded.

Upon completion of the first distillation, the product is called "Ordinario". After the second distillation, the product is called "Tequila". At this point the tequila normally has an alcohol content of 55% or higher. 55% alcohol is the equivalent of 110 proof. The product is then diluted with distilled water to reach the desired level of alcohol (normally 38 - 40%).
At this point, the tequila will be bottled as a blanco, silver, plata, etc., or it can be put to age in wooden barrels. Here it obtains its color, body, aroma and incomparable taste.As the tequila is aged in wooden barrels, usually oak, it becomes smoother, with a woody taste and golden color. Aging may disguise the agave flavor and few tequilas are aged longer than three to four years. Reposado may be put to age in barrels or casks as large as 20,000 liters, allowing for richer and more complex flavors. The preferred oak comes from US, France or Canada, and while they are usually white oak, some distillers prefer to char the wood for a smoky flavor, or use barrels that were previously used to hold a different kind of alcohol eg. whiskey, scotch, or wine. Some reposados can also be aged in new wood barrels to achieve the same wood flavor and smoothness in less time. Añejos are sometimes rested in barrels that have been previously used to rest reposados. The barrels cannot be more than 600 liters, although most are stored in barrels of about 200 liters. Many of the barrels used are from whiskey or bourbon distilleries in America, France, or Canada (the most popular being Jack Daniels), resulting in the dark color and more complex flavors of the añejo tequila. Because many people believe after 4 years of aging the tequila is at its best, the añejo can be removed from the wood barrels and placed in stainless steel tanks to reduce the amount of evaporation that can occur in the barrels.
Once the time arrives, it is bottled under strict quality control and supervision of the Mexican Government (NOM), the official Mexican Government norm and it is the Tequila Regulating Council who ratifies this by extending the origin certificate.

Fields of the Agave
Harvest of agaves

Cooking of agaves

Fermentation

Distillation
Filtering
Storage in the oak barrels