Editing Tequila (section)

==Fermentation==
Unlike other tequila production steps, [[Fermentation in food processing|fermentation]] is largely outside the control of human beings. Fermentation is the conversion of sugars and carbohydrates to alcohol through [[yeast]] under anaerobic conditions, meaning that oxygen is not present during the process.<ref name=":7">{{Cite web|url=http://www.ianchadwick.com/tequila/fermentation.htm|title=In Search of the Blue Agave: Fermenting Tequila|last=Chadwick|first=Ian|website=www.ianchadwick.com|access-date=2016-03-20|archive-date=2012-05-17|archive-url=https://web.archive.org/web/20120517090101/http://www.ianchadwick.com/tequila/fermentation.htm|url-status=live}}</ref> Fermentation is also carried out in a non-aseptic environment, which increases the bacterial activity of tequila.<ref name=":8">{{Cite news|url=http://www.scocia.com/newsite/Tequila.pdf.pdf|title=Production of tequila from agave: historical influences and contemporary processes|access-date=2016-03-23|archive-date=2016-04-08|archive-url=https://web.archive.org/web/20160408003535/http://www.scocia.com/newsite/Tequila.pdf.pdf|url-status=live}}</ref> The participation of [[microorganism]]s from the environment (yeasts and bacteria) makes fermentation a spontaneous process that gives rise to many byproducts that contribute to the flavor and aroma of tequila.<ref name=":8" />

During the fermentation process, [[Inoculum (fermentation starter)|inoculum]] is added to the batch to accelerate the rate of fermentation. When inoculum is added, fermentation can take approximately 20 hours to 3 days. If inoculum is not added, fermentation could take up to 7 days. The rate of fermentation is a key factor in the quality and flavor of tequila produced. Worts fermented slowly are best because the amount of organoleptic compounds produced is greater. The alcohol content at the end of fermentation is between 4-9%.<ref name=":8" />

===Organoleptic compounds===
[[File:TequilaFermentationVatMuseum.JPG|thumb|upright|Tequila fermentation vessel, [[National Museum of Tequila]]]]
[[Organoleptic]] compounds enhance flavor and aroma. These include [[fusel oil]], [[methanol]], [[aldehyde]]s, [[organic acid]]s and [[ester]]s.<ref name=":8" /> Production of [[Isoamyl alcohol|isoamyl]] and [[Isobutyl alcohol|isobutyl]] alcohols begins after the sugar level is lowered substantially and continues for several hours after the alcoholic fermentation ends. In contrast, ethanol production begins in the first hours of the fermentation and ends with logarithmic yeast growth. The alcohol content in tequila is affected by three factors: the amount of isoamyl alcohol and isobutanol in the yeast strain, the [[Carbon-to-nitrogen ratio|carbon:nitrogen ratio]] (the higher the ratio, the more alcohol produced), and the temperature of fermentation.

The higher the temperature, the greater concentration of isobutyl and isoamyl alcohols produced. Although if temperatures are too high, this can cause the yeast to become less effective. Similarly, if the temperature is too low, the process occurs too slowly.<ref name=":8" /> This can become a large issue in Central Mexico, most precisely the city of Tequila, Jalisco, where most tequila is processed. The temperature in the city of [[Tequila, Jalisco|Tequila]] can reach 31&nbsp;°C. For this reason, tequila producers often use large stainless steel tanks for fermentation.<ref name=":7" />

===Yeast===
The specific yeasts and the environments in which they act determine the resultant organoleptic combinations. The role of yeast is, through many enzymatic processes, to turn sugars and carbohydrates into alcohol. There are two steps, first in aerobic conditions, yeast is doubled in colony size every four hours. This process goes on for 24–48 hours. Next, yeast turns acetaldehyde into ethyl alcohol, which is known as one of the organoleptic compounds produced in fermentation.<ref name=":7" />

The two main categories of yeast used in tequila are commercial brewers yeast and yeast that comes from precultivated existing yeast that has been preserved. The use of either type of yeast can result in different end products of tequila.<ref name=":7" /> Traditional production uses so-called "open fermentation", relying on yeasts from the surrounding environment. A 2023 article analyzes the diversity of yeasts found in these uncontrolled conditions.<ref>{{cite journal |last1=Gallegos-Casillas |first1=Porfirio |last2=García-Ortega |first2=Luis F. |last3=Espinosa-Cantú |first3=Adriana |last4=Avelar-Rivas |first4=J. Abraham |last5=Torres-Lagunes |first5=Carolina G. |last6=Cano-Ricardez |first6=Adrián |last7=García-Acero |first7=Ángela M. |last8=Ruiz-Castro |first8=Susana |last9=Flores-Barraza |first9=Mayra |last10=Castillo |first10=Alejandra |last11=González-Zozaya |first11=Fernando |last12=Delgado-Lemus |first12=América |last13=Molina-Freaner |first13=Francisco |last14=Jacques-Hernández |first14=Cuauhtémoc |last15=Hernández-López |first15=Antonio |last16=Delaye |first16=Luis |last17=Aguirre-Dugua |first17=Xitlali |last18=Kirchmayr |first18=Manuel R. |last19=Morales |first19=Lucia |last20=Mancera |first20=Eugenio |last21=DeLuna |first21=Alexander |title=Yeast diversity in open agave fermentations across Mexico |journal=Yeast |date=January 2024 |volume=41 |issue=1–2 |pages=35–51 |doi=10.1002/yea.3913|doi-access=free }}</ref>