March 11, 2010
Dear Coyote patrons,
Last week I wrote about the milling process. When the agaves are milled and the sweet sugars have been extracted from their fibrous tissues the next step is to convert the sugars into alcohol. This process is called fermentation. Fermentation is the conversion of sugars (and –or carbohydrates) to alcohol by yeast. This biological conversion occurs when the agave juices (mosto) are allowed to rest in an open vat. The interaction between the bacteria and the yeast will consume the sugars and change them into a variety of sub products, such as ethyl alcohol and methanol. Later in the tequila process distillation will be needed eliminate the heavy alcohols that are body cannot digest.
The fermentation process can be induced by chemical yeast or can occur naturally from natural born yeast. Fermentation is an important step to the tequila process because it is during this phase that will depend on many final attributes in the finished product. If fermentation is not rushed the end product will have a more complex aromatic profile when it goes through the distillation process.
Fermentation can last between 2 -12 days depending on the alcohol grade desired and the atmospheric temperature. Warm weather between 68 -86 degrees Fahrenheit will result in a faster fermentation time. When the yeast have consumed the sugars and turned them into alcohol they are now called dead must (mosto muerto). After fermentation we have a juice that contains approximately 4-7 percent alcohols. This juice cannot be called tequila yet. It is now up to the master distiller to refine this liquid through the distillation process. Join us next week to learn about this careful process.
Café Coyote y Cantina