In the distilling companies that pride themselves on maintaining high and strict standards in the process, attached to achieving premium products. It is practically in the Jima where tequila production begins since the agaves are selected at their optimum point of maturity from the harvest.
Quality control begins upon arrival at the factory since upon receipt of the raw material, a sample of pineapples from each batch is randomly selected and analyzed in the laboratory to determine the appropriate levels of sugars and maturity and to establish the cooking times.
Before being introduced into the ovens, the pineapples are split into two or four parts according to their size, to favor perfect cooking and optimal use. Inside the ovens, the agaves are manually arranged. Once this operation is completed in the oven, the cooking process begins and continues for an average of 48 hours, injecting steam into the oven.
The purpose of this cooking is to achieve solubility and hydrolyze the agave sugars since inulin is not very soluble in water and cannot be fermented directly. In the traditional cooking process, masonry ovens are used, although currently, some tequila producers cook the agave in automatic retorts. After cooking, the agave pineapples allow the sugars to be broken down and the juices or musts are ready for fermentation.
After perfect cooking, the ovens are unloaded and the cooked pineapples are transferred to the milling area. Milling is divided into several stages and its purpose is to extract the sugars found in the agave fiber. This is carried out in mills ranging in structure from stone to crushers and stainless steel mills, depending on the manufacturer.
The milling stages begin with the tearing of the piñas, which consists of passing the cooked agave through a machine that shreds it and then takes it to a section where cane presses squeeze the juices, and once the fibrous material is squeezed, it passes through a section where water is applied for maximum extraction of the sugars.
As a result of this process, agave juice containing 12% sugars is obtained. This raw material is used to formulate the must or broth for fermentation.
Once the must is prepared for fermentation, it is inoculated with a microbial culture, which can be a pure wax of saccharomyces cerevisiae yeast or some other species.
When the must is ready, fermentation begins, one of the most important but least studied steps, since it is during this phase that the alcohol and other organoleptic components that makeup tequila are produced. This fermentation is carried out in stainless steel tanks of variable volume, covering and controlling the temperature, which ranges between 30 and 42 degrees Celsius.
This fermentation process can last between 12 and 72 hours, depending on the desired alcohol content, which can be 6% for mixed tequila and 45% for 100% tequila. Once the fermentation stage is finished, the must is left to rest to promote the generation of important aromatic compounds in the product.
There are two ways of distillation. By using alembic or column stills, the former being the more usual. In the first case, a tandem of two copper stills is regularly used, a material that helps to eliminate undesirable sulfur compounds.
In the first still, the dead wort is heated with steam and distilled to an ordinary intermediate product, with an alcohol concentration between 25 and 30%, from which the solids, part of the water, and the heads and tails have been removed. The former contains volatile components that distill before ethanol, below 80 degrees Celsius, such as methanol, isopropanol, and ethyl acetate, and the latter contains less volatile alcohols such as amyl and some esters.
In the second still, the ordinary tequila is distilled again to enrich the alcohol content to 55%, as well as considerably refining the product. This 55% tequila is considered a final product, as it is the one that is marketed in bulk. Before bottling, this distillate is diluted with deionized water to achieve a final product of 38 to 43%.
When using columns, up to three are used in tandem. In this case, the must flows into the column at the top, countercurrent with steam, which evaporates the volatile compounds that condense on the different plates of the column. Normally when columns are used instead of stills, the product is more neutral because the distillation is more selective.
Once distilled, the final product is concentrated in vats where it is diluted to pass it to the pipones or barrels where it will be aged, depending on the tequila to be obtained. In the maturation of tequilas, the last stage is carried out in oak or white oak barrels, woods that give the final product very peculiar aromas, colors, and flavors, which depend on several factors such as age, the thickness of the stave, alcohol content and conditions of rest or aging.
Humidity and ventilation conditions are very important since the aging process involves oxidative reactions. Finally, before bottling it is necessary to remove some solids conferred by the wood. This is done through filtration with cellulose or activated carbon.