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How long does fermentation usually take under normal conditions?
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distilled spirit
The fermentation and distillation process for producing whiskey. The production of whiskey begins with grinding grain into a meal, which is cooked. Malt is introduced to the meal, which results in mash that is cooled and pumped into a fermenter, where yeast is added. The fermented mixture is heated in a still, where the heat vaporizes the alcohol. The alcohol vapours are caught, cooled, condensed, and drawn off as clean, new whiskey. This liquid is stored in a cistern room, and water is added to lower the proof (absolute alcohol content) before the whiskey is placed in new charred oak barrels for aging and later bottling.
In the production of distilled spirits, the time required for fermentation is primarily dependent on the temperature of the fermenting mash. Under normal conditions, where yeast is most effective at temperatures ranging from 24 to 29 °C (75 to 85 °F), the completion of fermentation typically requires between 48 and 96 hours.1
If fermentation is conducted at lower temperatures, the process requires longer periods to reach completion. It is important to manage this timing carefully, as allowing fermentation to continue beyond the necessary period can lead to bacterial action that reduces the ethyl alcohol content and taints the flavor and aroma of the finished product.1