Sour mash (or sourmash) is a process used in the distilling industry that uses material from an older batch of mash to start the fermentation of a new batch, analogous to the making of sourdough bread with a starter. The term can also be used as the name of the type of mash used in such a process, and a

bourbon Bourbon may refer to: Food and drink * Bourbon whiskey, an American whiskey made using a corn-based mash * Bourbon barrel aged beer, a type of beer aged in bourbon barrels * Bourbon biscuit, a chocolate sandwich biscuit * A beer produced by ...

made using this process can be referred to as a ''sour mash bourbon''. Sour beer may also be created with this process.

Process

In the sour mash process, the mash – a mixture of

grain A grain is a small, hard, dry fruit ( caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legu ...

malt Malt is germinated cereal grain that has been dried in a process known as " malting". The grain is made to germinate by soaking in water and is then halted from germinating further by drying with hot air. Malted grain is used to make beer, ...

and water – is conditioned with some amount of spent mash (previously fermented mash that still contains dead yeast, a good food source for live yeast). Spent mash is also known as spent beer, distillers' spent grain, and slop or feed mash because it is also used as animal feed. The acid introduced by the sour mash controls the growth of bacteria that could taint the Bourbon. An established and active strain of live yeast is introduced into the mash to be fermented. By using an established and known fermented "sour", this fermentation process controls the introduction and growth of foreign bacteria and yeasts that could damage the Bourbon and improves the consistency and quality of the

liquor Liquor (or a spirit) is an alcoholic drink produced by distillation of grains, fruits, vegetables, or sugar, that have already gone through alcoholic fermentation. Other terms for liquor include: spirit drink, distilled beverage or ha ...

, ensuring every bottle tastes as similar as possible. Sour mashing is also a process sometimes used in

brewing Brewing is the production of beer by steeping a starch source (commonly cereal grains, the most popular of which is barley) in water and fermenting the resulting sweet liquid with yeast. It may be done in a brewery by a commercial brewer, ...

to make sour beers in a short time frame. In the brewing version of sour mashing, brewers mash in their grains to begin the brewing process, but instead of extracting the wort from the grains at the end of the mash (typically in less than 90 minutes), the brewer leaves the grains and wort together for as long as several days before draining the wort. During this time, the

lactic acid bacteria Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped ( bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...

naturally present on the grain ferment some of the sugars in the wort into lactic acid. This lactic acid adds sourness to the beer. In order to promote fast bacterial fermentation and reduce yeast activity, the mash is kept between . The brewer extracts the wort by

sparging Sparging may refer to: *Sparging (chemistry), a process in which a gas is bubbled through a liquid to remove other gases or volatile compounds *Air sparging, a remediation process in which air is pushed through contaminated water or soil to remove ...

when they believe enough acid has been produced. Some beers employing sour mashing are fermented with the addition of brewing yeast but without a boil. Other brewers prefer to boil their sour mashed beer and then ferment it with brewing yeast. The resulting beers can range from mildly tart to noticeably sour.

References

External links

* {{Whisky Bourbon whiskey

Process

See also

References

External links