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.[1]
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.[2]
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%).[3]
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.[4][1]
Beer potassium content: Beer typically contains 300 to 500 mg/L potassium.[1] 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.[5] A possible exception to this is water that has been run through a "water softener" using potassium chloride.[6][7]
- Grain - Malt is the primary source of potassium in wort and beer, adding 300–500 mg/L.[1]
- 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.[1] However, it can taste salty (similar to sodium), but only at concentrations greater than 500 mg/L.[1] It is more acceptable than sodium from a flavor point of view, giving a salty taste without sour notes.[2]
See also
References
- ↑ a b c d e f Taylor DG. Water. In: Stewart GG, Russell I, Anstruther A, eds. Handbook of Brewing. 3rd ed. CRC Press; 2017.
- ↑ a b Montanari L, Mayer H, Marconi O, Fantozzi P. Chapter 34: Minerals in beer. In: Preedy VR, ed. Beer in Health and Disease Prevention. Academic Press; 2009:359–365.
- ↑ White C. Yeast nutrients make fermentations better. White Labs. Accessed 2020.
- ↑ Palmer J, Kaminski C. Water: A Comprehensive Guide for Brewers. Brewers Publications; 2013.
- ↑ Chapter 11: Water and Electrolytes. In: Recommended Dietary Allowances. 10th ed. National Academies Press (US); 1989.
- ↑ Potassium in drinking-water. World Health Organization. 2009. Accessed online April 2024.
- ↑ Guidance on potassium from water softeners. Health Canada. 2008. Accessed online April 2024.