Potassium

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Potassium ions are actively transported into fermenting yeast cells where they neutralize charges on nucleic acids and proteins and contribute to osmoregulation.

Potassium is required for yeast growth, and like magnesium, is a yeast co-factor that is required at trace levels for satisfactory fermentation. Potassium is particularly necessary for the metabolism of carbohydrates and supports all enzymatic reactions which proceed with ATP.

Potassium (K⁺) has many functions within the cell, and can represent up to 2% of the dry cell weight of yeast cells, very high for a mineral (most are under 0.1%).

Potassium salts may be preferred vs sodium as a means of increasing anion (e.g. chloride) content of beers, since even significant amounts of potassium (e.g. up to 200ppm) probably would not be noticed.

Beer potassium content: Beer typically contains 300 to 500 mg/L potassium. This amount is naturally extracted from the malt.

Potential sources of potassium

• Brewing water - Tap water generally contains a negligible amount of potassium, around 2 mg/L. A possible exception to this is water that has been run through a "water softener" using potassium chloride.
• Grain - Malt is the primary source of potassium in wort and beer, adding 300–500 mg/L.
• Salt additives - Brewers do not need to increase the potassium level of wort, although the brewing salts used to increase other minerals can contain potassium, such as potassium chloride

Effects of potassium

• Flavor - Potassium has no flavor at the concentrations normally found in beer. However, it can taste salty (similar to sodium), but only at concentrations greater than 500 mg/L. It is more acceptable than sodium from a flavor point of view, giving a salty taste without sour notes.

See also

• Water