So what actually is Sour Mash Whiskey?
Well it's Bourbon or Tennessee whiskey made using at least 25 per cent backset; soured yeast mash; with a fermentation period of at least 72 hours.
In North American Sour Mash Whiskey, alcohol-free liquid left at the bottom of the still after distillation is added to the mash tub and fermenter to ward off bacterial contamination.
The Mash, is the liquid composed of grist, mixed with boiling water.
This extracts soluble starch, which is converted into maltose by the enzyme amylase.
The liquid that is drained from the mash tun and fermented is called the worts.
Sour Mash Whiskey, which also is sippin’ whiskey and Tennessee whiskey, is a frequently misunderstood term.
Sour mash simply refers to the technique used in the preparation of most, if not all, straight whiskey.
The sour mash method makes the yield more efficient.
The technique involves seeding, or seasoning, a new batch of mash with a portion of the previous day’s mash. This is known as “baskset,” “setback” or “stilling back” and is taken from the base of the still.
It may be added to the grain mash in the cooker, the yeast mash, the fermenting vessels, or all three.
This sour mash process helps ensure that the new run of Sour Mash Whiskey will have exact same taste as the previous day’s distillation.
The process ensures continuity in fermentation and guards against the invasion of wild yeast.
Sour mash got its name because the thin spirit “beer” remaining had a slightly acidic taste, although the resultant whiskey was anything but sour.