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Magnesium (Mg<sup>2+</sup>) is a mineral naturally present in [[water]] and [[grain]]. It is one of the most important ions for fermentation performance.<ref name=gib125/><ref name=walden>Walker G, De Nicola R, Anthony S, Learmonth R. [https://research.usq.edu.au/download/286887950bc7e5fc18959042c5efa3ddb1798fc69584bc7ae41fb1680bbf81b6/239682/Walker-De_Nicola__Anthony_Learmonth_aper_IBD_Hobart_2006.pdf Yeast-metal interactions: impact on brewing and distilling fermentations.] In: Proceedings of the Institute of Brewing & Distilling Asia Pacific Section 2006 Convention. 2006.</ref><ref name=monmay>Montanari L, Mayer H, Marconi O, Fantozzi P. [https://www.sciencedirect.com/science/article/abs/pii/B9780123738912000341 Chapter 34: Minerals in beer.] In: Preedy VR, ed. [[Library|''Beer in Health and Disease Prevention.'']] Academic Press; 2009:359–365.</ref> Magnesium is required for the function of over 300 [[enzymes]], making it a necessary nutrient for yeast growth and fermentation.<ref name=salsla>Saltukoglu A, Slaughter JC. [https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.1983.tb04151.x The effect of magnesium and calcium on yeast growth.] ''J Inst Brew.'' 1983;89(2):81–83.</ref><ref name=walbir>Walker GM, Birch RM, Chandrasena G, Maynard AI. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-54-0013 Magnesium, calcium, and fermentative metabolism in industrial yeasts.] ''J Am Soc Brew Chem.'' 1996;54(1):13–18.</ref><ref name=reeste/><ref name=korbog>Kordialik‐Bogacka E, Bogdan P, Ciosek A. [https://ifst.onlinelibrary.wiley.com/doi/abs/10.1111/ijfs.14052 Effects of quinoa and amaranth on zinc, magnesium and calcium content in beer wort.] ''Int J Food Sci Technol.'' 2019;54(5):1706–1712.</ref> Magnesium is also an important component of beer flavor, imparting a lightly sour and astringent or bitter character. However, as the level of magnesium increases, the flavor may become unpleasant. At excessive levels (higher than 125 mg/L in beer), magnesium can have possible diuretic or laxative effects, although the latter is unlikely.<ref name=water/><ref name=bsp/> To avoid any negative effects, it is suggested to have no more than 20–40 mg/L magnesium in the brewing water.<ref name=hob10/><ref name=bsp/><ref name=water/><ref name=eumsch/> The presence of some magnesium in the brewing water is widely considered to be beneficial, although there is no consensus on the ideal amount.<ref name=water/><ref name=comrie>Comrie AA. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1967.tb03050.x Brewing liquor—a review.] ''J Inst Brew.'' 1967;73(4):335–346.</ref> Magnesium behaves similarly to [[calcium]], and the effects of these two ions have some interesting interactions.<ref name=water/> Magnesium is classified as an alkaline-earth metal.


Magnesium (Mg<sup>2+</sup>) is a mineral naturally present in [[water]] and [[grain]]. It is one of the most important ions for fermentation performance.<ref name=gib125/> Magnesium is required for the function of over 100 [[enzymes]], making it a necessary nutrient for yeast growth and fermentation.<ref name=salsla>Saltukoglu A, Slaughter JC. [https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.1983.tb04151.x The effect of magnesium and calcium on yeast growth.] ''J Inst Brew.'' 1983;89(2):81–83.</ref> Magnesium is also an important component of beer flavor, imparting a lightly sour and astringent or bitter character. However, as the level of magnesium increases, the flavor may become unpleasant. At excessive levels (higher than 125 mg/L in beer), magnesium can have possible diuretic or laxative effects, although the latter is unlikely.<ref name=water/><ref name=bsp/> To avoid any negative effects, it is suggested to have no more than 20–40 mg/L magnesium in the brewing water.<ref name=hob10/><ref name=bsp/><ref name=water/> The presence of some magnesium in the brewing water is widely considered to be beneficial, although there is no consensus on the ideal amount.<ref name=water/><ref name=comrie>Comrie AA. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1967.tb03050.x Brewing liquor—a review.] ''J Inst Brew.'' 1967;73(4):335–346.</ref> Magnesium behaves similarly to [[calcium]], and the effects of these two ions have some interesting interactions.<ref name=water/>
'''Beer magnesium content:''' Commercial beers typically contain around 60 to 150 mg/L magnesium.<ref name=omacha>Omari IO, Charnock HM, Fugina AL, Thomson EL, McIndoe JS. [https://www.tandfonline.com/doi/abs/10.1080/03610470.2020.1795437 Magnesium-accelerated Maillard reactions drive differences in adjunct and all-malt brewing.] ''J Am Soc Brew Chem.'' 2021;79(2):145–155.</ref><ref name=kunze>Kunze W. Hendel O, ed. [[Library|''Technology Brewing & Malting.'']] 6th ed. VLB Berlin; 2019.</ref> Almost all of the magnesium from the ingredients will be present in the final beer, as only a small amount is taken up by the yeast.


== Potential sources of magnesium ==
== Potential sources of magnesium ==
* '''Brewing water''' - The [[water]] used to make beer may contain dissolved magnesium.
The magnesium content in beer comes from the raw ingredients, mainly the water and grist, plus any salts added by the brewer.
* '''Grain''' - Magnesium has high extractability compared to that of other metals, up to 80%.<ref name=gib125/> A typical wort provides around 50–90 mg/L magnesium extracted from the grain,<ref name=gib125>Gibson BR. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2011.tb00472.x 125th anniversary review: improvement of higher gravity brewery fermentation via wort enrichment and supplementation.] ''J Inst Brew.'' 2011;117(3):268–284.</ref><ref name=water/> although a large portion may be bound to organic molecules (limiting the amount available to the yeast).<ref name=salsla/>
* '''Brewing water''' - The [[water]] used to make beer may contain dissolved magnesium. North American municipal tap water typically contains 0–48 mg/L magnesium, with an average around 8–12 mg/L.<ref name=azogar>Azoulay A, Garzon P, Eisenberg MJ. [https://onlinelibrary.wiley.com/doi/full/10.1111/j.1525-1497.2001.04189.x Comparison of the mineral content of tap water and bottled waters.] ''J Gen Intern Med.'' 2001;16(3):168–175.</ref><ref>Tackaberry R. [https://www.mgwater.com/mgrank.shtml Mineral content of drinking water, 100 USA cities.] The Magnesium Web Site. 2002. Accessed online April 2024.</ref><ref name=burdie>Burlingame GA, Dietrich AM, Whelton AJ. [https://awwa.onlinelibrary.wiley.com/doi/abs/10.1002/j.1551-8833.2007.tb07930.x Understanding the basics of tap water taste.] ''J Am Water Works Assoc.'' 2007;99(5):100–111.</ref> Ground water tends to have higher magnesium than surface water. American bottled waters contain 0–95 mg/L, although the average is very low at 3–8 m/L. European bottled water contains higher magnesium levels. Note that some tap water and some bottle waters exceed the recommended level of magnesium, making them unsuitable for brewing.
* '''Salt additives''' - Brewers can enrich the magnesium level of the wort during [[mashing]] or [[boiling]] by adding brewing salts that contain magnesiumm, such as [[magnesium chloride]] or [[magnesium sulfate]].
* '''Grain''' - Magnesium has high extractability compared to that of other metals, up to 80%.<ref name=gib125/> A typical wort provides around 50–90 mg/L magnesium extracted from the grain.<ref name=gib125>Gibson BR. [https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2011.tb00472.x 125th anniversary review: improvement of higher gravity brewery fermentation via wort enrichment and supplementation.] ''J Inst Brew.'' 2011;117(3):268–284.</ref><ref name=water/><ref name=holpie>Holzmann A, Piendl A. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-35-0001 Malt modification and mashing conditions as factors influencing the minerals of wort.] ''J Am Soc Brew Chem.'' 1977;35(1):1–8.</ref> However, a large portion of the measured magnesium may be bound to organic molecules, which greatly reduces the amount available to the yeast (grain-extracted magnesium has low bioavailablility).<ref name=walbir/><ref name=salsla/> The magnesium content of grain can vary widely, probably due to fertilizer usage.<ref name=omacha/>
* '''Salt additives''' - Brewers can enrich the magnesium level of the wort by adding brewing salts that contain magnesiumm, such as [[magnesium chloride]] or [[magnesium sulfate]]. Magnesium added from these salts will increase the amount available to be taken up by the yeast.


== Effects of magnesium ==
== Effects of magnesium ==
* '''Improved pH control''' - Magnesium beneficially lowers the [[brewing pH|pH]] during mashing by precipitating with [[phosphates]], [[protein|proteins]], and other compounds, although not as effectively as calcium because magnesium salts are much more soluble.<ref name=bsp/><ref name=hob/><ref>Eumann M, Schildbach S. [https://onlinelibrary.wiley.com/doi/10.1002/jib.18 125<sup>th</sup> anniversary review: Water sources and treatment in brewing.] ''J Inst Brew.'' 2012;118:12–21.</ref><ref name=bsp/><ref name=water/>
In the context of brewing beer, magnesium has several important effects.
* '''Improved fermentation''' - Magnesium ions are needed by many yeast enzymes, such as pyruvate decarboxylase.<ref name=salsla/><ref name=bsp>Briggs DE, Boulton CA, Brookes PA, Stevens R. [[Library|''Brewing Science and Practice.'']] Woodhead Publishing Limited and CRC Press LLC; 2004.</ref><ref name=water>Palmer J, Kaminski C. [[Library|''Water: A Comprehensive Guide for Brewers.'']] Brewers Publications; 2013.</ref><ref name=hob/><ref name=gib125/> In fact, magnesium is required for yeast growth and metabolism (fermentation), and can help improve yeast ethanol tolerance and improve the ability of yeast to ferment under stressful conditions.<ref name=gib125/><ref name=hob/><ref>White C. [https://www.jstrack.org/brewing/Yeast_nutrition_article.pdf Yeast nutrients make fermentations better.] White Labs. Accessed 2020.</ref> The magnesium extracted from grain typically provides the minimum amount of magnesium needed to support fermentation, although the level is usually not optimal.<ref name=gib125/><ref name=water/><ref name=salsla/> Additional magnesium in the brewing water can sometimes improve fermentation speed, particularly a faster onset of fermentation.<ref name=hob10>Ryder DS. Processing aids in brewing. In: Stewart GG, Russell I, Anstruther A, eds. [[Library|''Handbook of Brewing.'']] 3rd ed. CRC Press; 2017.</ref><ref name=salsla/> Calcium ions inhibit magnesium absorption by the yeast,<ref name=gib125/> and therefore magnesium addition may be especially useful in wort with a high calcium level (e.g. from the water or calcium salt additions).
* '''Improved pH control''' - Magnesium beneficially lowers the [[brewing pH|pH]] during mashing by precipitating with [[phosphates]], [[protein|proteins]], and other compounds, although not as effectively as calcium because magnesium salts are much more soluble.<ref name=bsp/><ref name=hob/><ref name=eumsch>Eumann M, Schildbach S. [https://onlinelibrary.wiley.com/doi/10.1002/jib.18 125<sup>th</sup> anniversary review: Water sources and treatment in brewing.] ''J Inst Brew.'' 2012;118:12–21.</ref><ref name=bsp/><ref name=water/>
* '''Increased Maillard reactions''' - Magnesium promotes [[Maillard reaction]]s between sugars and amino acids, which may or may not visibly increase beer color or have an impact on flavor (this has not been well studied).<ref name=omacha/>
* '''Improved fermentation''' - Magnesium ions are needed by many yeast enzymes, such as pyruvate decarboxylase.<ref name=salsla/><ref name=bsp>Briggs DE, Boulton CA, Brookes PA, Stevens R. [[Library|''Brewing Science and Practice.'']] Woodhead Publishing Limited and CRC Press LLC; 2004.</ref><ref name=water>Palmer J, Kaminski C. [[Library|''Water: A Comprehensive Guide for Brewers.'']] Brewers Publications; 2013.</ref><ref name=hob/><ref name=gib125/> In fact, magnesium is required for yeast growth and metabolism (fermentation).<ref name=gib125/><ref name=walbir/><ref name=hob/><ref>White C. [https://www.jstrack.org/brewing/Yeast_nutrition_article.pdf Yeast nutrients make fermentations better.] White Labs. Accessed 2020.</ref> The magnesium extracted from grain typically provides the minimum amount of magnesium needed to support fermentation, although the level is usually not optimal.<ref name=gib125/><ref name=water/><ref name=salsla/><ref>Walker GM. [https://rke.abertay.ac.uk/en/publications/role-of-metal-ions-in-brewing-yeast-fermentation-performance Role of metal ions in brewing yeast fermentation performance.] In: Smart KA, ed. ''Brewing Yeast Fermentation Performance.'' 1st ed. Wiley-Blackwell; 2000:86–91.</ref> Additional magnesium can sometimes improve fermentation rate, including faster onset of fermentation, and can sometimes help improve yeast ethanol tolerance and improve the ability of yeast to ferment under stressful conditions, increasing sugar uptake and alcohol production.<ref name=hob10>Ryder DS. Processing aids in brewing. In: Stewart GG, Russell I, Anstruther A, eds. [[Library|''Handbook of Brewing.'']] 3rd ed. CRC Press; 2017.</ref><ref name=salsla/><ref name=gib125/><ref name=walbir/><ref name=brobow/><ref>Walker GM. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-56-0109 Magnesium as a stress-protectant for industrial strains of Saccharomyces cerevisiae.] ''J Am Soc Brew Chem.'' 1998;56(3):109–113.</ref> Calcium ions inhibit magnesium absorption by the yeast,<ref name=gib125/> and therefore magnesium addition may be especially useful in wort with a high calcium level (e.g. from the water or calcium salt additions).<ref name=walbir/> Note that the response is strain-dependent.<ref name=walbir/><ref name=reeste>Rees EM, Stewart GG. [https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.1997.tb00958.x The effects of increased magnesium and calcium concentrations on yeast fermentation performance in high gravity worts.] ''J Inst Brew.'' 1997;103(5):287–291.</ref><ref name=brobow>Bromberg SK, Bower PA, Duncombe GR, et al. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-55-0123 Requirements for zinc, manganese, calcium, and magnesium in wort.] ''J Am Soc Brew Chem.'' 1997;55(3):123–128.</ref>
* '''Improved yeast flocculation''' - Magnesium ions can positively influence flocculation, substituting for calcium.<ref name=gib125/> This effect can be inhibited by the presence of metal-chelating agents (i.e. [[tannin additives]]) since magnesium is more sensitive to chelation than calcium.
* '''Flavor''' - At the moderate levels typically found in wort, magnesium can enhance a beer's character by providing a mild sour or bitter [[astringency]].<ref name=water/><ref name=smart1>Howe S. Raw materials. In: Smart C, ed. [[Library|''The Craft Brewing Handbook.'']] Woodhead Publishing; 2019.</ref><ref name=hob>Taylor DG. Water. In: Stewart GG, Russell I, Anstruther A, eds. [[Library|''Handbook of Brewing.'']] 3rd ed. CRC Press; 2017.</ref><ref name=bsp/><ref name=habkos>Habschied K, Košir IJ, Krstanović V, Kumrić G, Mastanjević K. [https://www.mdpi.com/2306-5710/7/2/38 Beer polyphenols—bitterness, astringency, and off-flavors.] ''Beverages.'' 2021;7(2):38.</ref><ref name=comrie/> At excessive levels, the sour and bitter notes can become unpleasant and harsh.<ref name=water/><ref>Fix G. [[Library|''Principles of Brewing Science.'']] 2nd ed, Brewers Publications; 1999.</ref> These flavor effects appear to depend on a balance between the magnesium and [[calcium]] ions, since calcium can reduce the flavor impact of magnesium.<ref name=hob/>
* '''Flavor''' - At the moderate levels typically found in wort, magnesium can enhance a beer's character by providing a mild sour or bitter [[astringency]].<ref name=water/><ref name=smart1>Howe S. Raw materials. In: Smart C, ed. [[Library|''The Craft Brewing Handbook.'']] Woodhead Publishing; 2019.</ref><ref name=hob>Taylor DG. Water. In: Stewart GG, Russell I, Anstruther A, eds. [[Library|''Handbook of Brewing.'']] 3rd ed. CRC Press; 2017.</ref><ref name=bsp/><ref name=habkos>Habschied K, Košir IJ, Krstanović V, Kumrić G, Mastanjević K. [https://www.mdpi.com/2306-5710/7/2/38 Beer polyphenols—bitterness, astringency, and off-flavors.] ''Beverages.'' 2021;7(2):38.</ref><ref name=comrie/> At excessive levels, the sour and bitter notes can become unpleasant and harsh.<ref name=water/><ref>Fix G. [[Library|''Principles of Brewing Science.'']] 2nd ed, Brewers Publications; 1999.</ref> These flavor effects appear to depend on a balance between the magnesium and [[calcium]] ions, since calcium can reduce the flavor impact of magnesium.<ref name=hob/>
* '''Increased hop utilization''' - Magnesium increases humulone isomerization, which may contribute to its perceived bitter flavor effect.<ref name=omacha/>


== How to adjust the magnesium level ==
== How to adjust the magnesium level ==
In order to ensure a good [[fermentation]], the addition of some magnesium to brewing water may be desirable.<ref name=hob10/> While [[magnesium sulfate]] (e.g. Epsom salt) is a common traditional option, [[magnesium chloride]] is also a good option for adding magnesium if you would prefer to minimize that amount of [[sulfate]]. Magnesium content in yeast extracts (i.e. [[yeast nutrient products]]) can also improve the fermentation performance of yeast, although adding a magnesium salt might be more beneficial.<ref name=gib125/>
In order to ensure a good [[fermentation]], the presence of some magnesium in brewing water is recommended.<ref name=hob10/> While [[magnesium sulfate]] (e.g. Epsom salt) is a common traditional option, [[magnesium chloride]] is also a good option for adding magnesium if you would prefer to minimize the amount of [[sulfate]]. Magnesium content in yeast extracts (i.e. [[yeast nutrient products]]) can also improve the fermentation performance of yeast, although adding a magnesium salt might be more beneficial.<ref name=gib125/> When considering the potential of magnesium to improve yeast fermentation performance, the concentration of wort calcium should also be taken into account.<ref name=gib125/> Calcium competes with magnesium for uptake by the yeast, and any observed improvement may be related to the Mg:Ca ratio rather than the absolute concentration of magnesium.<ref name=gib125/><ref name=walbir/> See [[Water]] for our guide to adjusting water minerals and mash pH.


If the magnesium level in your tap water is too high, the only option to decrease it for use as brewing water is to purify it with a [[RO systems|reverse osmosis system]]. Yeast can theoretically absorb a maximum of 30–45 mg/L of magnesium during a typical fermentation, which can help to lower the amount in the final beer.<ref name=salsla/>
If the magnesium level in your tap water is too high, the only method to decrease the level is to purify the water with a [[RO systems|reverse osmosis system]]. Yeast can theoretically absorb a maximum of 30–45 mg/L of magnesium during a typical fermentation, only mildly lowering the amount in the final beer.<ref name=salsla/>
 
 
 
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Supplementation of both standard (12°P) and high gravity (20°P) worts with Mg (500 ppm) results in higher fermentation rates, increased uptake of maltose and maltotriose and increased production of ethanol, with up to an extra 5 mL ethanol L–1 produced during high gravity fermentation when Mg had been added as a supplement172,174. This promotion of fermentation performance by Mg was observed for both ale and lager strains172,174 and later with wine yeast fermenting grape must. It is probable that most brewery worts do not contain optimal levels of Mg, and even when wort Mg was increased from a basal level of 75 ppm to 135 ppm, improvement in 16°P wort fermentation performance with a lager yeast strain was not observed31. An alternative to wort supplementation is the ‘pre-conditioning’ of yeast cells by propagation in Mgrich wort. The Mg-rich cells produced have greater ethanol productivity in subsequent wort fermentations than their ‘non-conditioned’ counterparts223. Such pre-conditioning can increase cellular Mg levels by several-fold, depending on the Mg concentration of the propagation medium and duration of exposure191. Much of this Mg may be released when cells are pitched into fresh fermentation wort and this phenomenon has been proposed as a measure of the potential fermentation performance of a pitched yeast147. When considering the potential of Mg to improve yeast fermentation performance, the concentration of wort Ca should also be taken into account. Ca and Mg act antagonistically and any observed improvement may be related to the Mg:Ca ratio rather than the absolute concentration of Mg. Rees et al.172 reported faster fermentation rates at Mg:Ca ratios of 17:1 and 11:1 for 12°P and 20°P worts, respectively, compared with unsupplemented worts with Mg:Ca ratios of 3:1 or 2.5:1. Bromberg et al.31 did not observe an improvement in fermentation performance with higher Mg relative to Ca, though in that case the highest ratio present in wort was 4:1. Mg ions can positively influence flocculation and at a concentration of 10 ppm may substitute Ca under experimental conditions195. This characteristic may be relevant to brewery fermentation where the wort Mg concentration can be several fold greater than that of Ca172. Promotion of flocculation in a lager strain by Mg occurred between 12.5 ppm and 25 ppm Mg and was reversed when the Mg concentration was raised to 2,500 ppm. Increased flocculation of cells from a top-fermenting ale strain was observed at 2,500 ppm Mg51. The deflocculation of lager strain cells at 2,500 ppm Mg may be due to competition of Mg for the Ca-lectin binding sites51. Mg-induced flocculation is more sensitive to the presence of metal-chelating agents than Ca-induced flocculation and it is likely that the greater specificity of Ca in yeast flocculation relates to a greater affinity for cell wall-binding sites51,198. Smit et al.190 reported that onset of flocculation was triggered in a lager strain by the depletion of any of a number of different nutrients from the growth media. The exception was Mg, the loss of which did not result in flocculation, suggesting that nutritional Mg has a role in the process. This role is not fully understood but may relate to cell surface hydrophobicity, which is reduced in cells grown in Mg-limited media (0.7 ppm). Inclusion of Mg in the assay medium did not increase the hydrophobicity (or flocculation potential) of the cells in that study190. Apart from the metabolic requirements of yeast for Mg during fermentation, these ions also have a well-documented role in protecting yeast from the toxic effects of ethanol and may therefore influence fermentation performance during higher gravity brewery fermentations. Mg supplementation reduces the toxic effect of ethanol in defined media. Walker222 reported viabilities of 0% and 53% in a wine strain exposed to 10% ethanol for 24 hours in the presence of 50 ppm and 500 ppm Mg, respectively. Likewise, Hu et al.88 showed that 9 hours of exposure of yeast cells to 20% ethanol led to the death of all cells in a population, whereas supplementation of the same medium with 85 ppm Mg resulted in viabilities of between 25 and 55% depending on duration of Mg exposure. Increasing Mg concentration led to increased resistance of brewing and distilling yeast to the toxic effects of ethanol222. It was proposed that Mg exerted its protective influence on the plasma membrane and, interestingly, Mg also protected cells against the effects of heat shock222. Ethanol and heat shock affect cell membranes in a similar manner164 and Mg may therefore have a general protective effect on the yeast cell plasma membrane. Increased membrane permeability in response to ethanol exposure is well documented40,75,103,169,182 and the protective effect of Mg has been attributed to its ability to prevent excessive loss of ions162 and nucleotides88 from the yeast cell. The presence of Mg obviates the requirement for heat shock protein synthesis, which would otherwise be needed to maintain plasma membrane integrity on exposure to ethanol23. Increased resistance to ethanol is conferred regardless of whether Mg is included in the yeast growth medium as a pre-conditioning step or whether it is added as a supplement concomitant with ethanol exposure23,88, raising the question of how exactly it acts to maintain plasma membrane integrity under stressful conditions. Increased availability of Mg during higher gravity brewery fermentations may also benefit fermentation performance by mitigating the effects of osmotic stress on the cells47. Improvement of fermentation performance and stress tolerance of brewing yeast occurring as a result of Mg supplementation is clearly an attractive approach to increase productivity of higher gravity brewery fermentations. The potential negative effects of Mg on flocculation should however be considered, as well as the potential of these ions to influence the uptake of other essential metals such as Mn24 and the ultimate effect of Mg supplementation on beer quality indicators.<ref name=gib125/>


== See also ==
== See also ==
* [[Water]] - Expert guide to adjusting water minerals
* [[Water]] - Expert guide to adjusting water minerals
* [[Brewing pH]] - Discussion of pH throughout the brewing process, including the benefits of pH control by adjusting calcium.
* [[Magnesium chloride]] - Brewing salt
 
* [[Magnesium sulfate]] - Brewing salt
Potential sources
*https://www.tandfonline.com/doi/abs/10.1080/03610470.2020.1795437
*https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-54-0013
*https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.1997.tb00958.x
*https://ifst.onlinelibrary.wiley.com/doi/abs/10.1111/ijfs.14052
*https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.1997.tb00941.x
*https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-55-0123
*https://research.usq.edu.au/item/9xvxx/yeast-metal-interactions-impact-on-brewing-and-distilling-fermentations
*https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.1999.tb00021.x
*https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-56-0109
*https://www.sciencedirect.com/science/article/pii/B9780123738912000341
*https://www.mdpi.com/2218-273X/10/12/1599
*https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-35-0001
*https://www.sciencedirect.com/science/article/pii/S0023643820313372
*https://rke.abertay.ac.uk/en/publications/role-of-metal-ions-in-brewing-yeast-fermentation-performance
*https://www.sciencedirect.com/science/article/pii/S0963996922011024
*https://www.tandfonline.com/doi/abs/10.1080/0957126032000114973
*https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2015-0402-01
*https://onlinelibrary.wiley.com/doi/abs/10.1002/jib.226
*https://www.sciencedirect.com/science/article/pii/S0141022908003293


== References ==
== References ==
[[Category:Brewing chemistry]]
[[Category:Brewing chemistry]]
{{#seo:
|title=Magnesium in brewing: sources, effects, and ideal level
|description=Magnesium is one of the most important brewing minerals due to its beneficial effects on fermentation performance, pH control, and beer flavor. Although malt contributes a substantial amount of magnesium, it is potentially beneficial for brewers to add extra magnesium to help improve fermentation. High levels of magnesium in brewing water is undesirable since it can cause harsh sour and bitter flavors, along with other possible negative effects.
|image=Magnesium.png
|image_alt=Magnesium periodic table emblem
}}

Latest revision as of 10:47, 10 May 2024

Magnesium periodic table emblem

Magnesium (Mg2+) is a mineral naturally present in water and grain. It is one of the most important ions for fermentation performance.[1][2][3] Magnesium is required for the function of over 300 enzymes, making it a necessary nutrient for yeast growth and fermentation.[4][5][6][7] Magnesium is also an important component of beer flavor, imparting a lightly sour and astringent or bitter character. However, as the level of magnesium increases, the flavor may become unpleasant. At excessive levels (higher than 125 mg/L in beer), magnesium can have possible diuretic or laxative effects, although the latter is unlikely.[8][9] To avoid any negative effects, it is suggested to have no more than 20–40 mg/L magnesium in the brewing water.[10][9][8][11] The presence of some magnesium in the brewing water is widely considered to be beneficial, although there is no consensus on the ideal amount.[8][12] Magnesium behaves similarly to calcium, and the effects of these two ions have some interesting interactions.[8] Magnesium is classified as an alkaline-earth metal.

Beer magnesium content: Commercial beers typically contain around 60 to 150 mg/L magnesium.[13][14] Almost all of the magnesium from the ingredients will be present in the final beer, as only a small amount is taken up by the yeast.

Potential sources of magnesium[edit]

The magnesium content in beer comes from the raw ingredients, mainly the water and grist, plus any salts added by the brewer.

  • Brewing water - The water used to make beer may contain dissolved magnesium. North American municipal tap water typically contains 0–48 mg/L magnesium, with an average around 8–12 mg/L.[15][16][17] Ground water tends to have higher magnesium than surface water. American bottled waters contain 0–95 mg/L, although the average is very low at 3–8 m/L. European bottled water contains higher magnesium levels. Note that some tap water and some bottle waters exceed the recommended level of magnesium, making them unsuitable for brewing.
  • Grain - Magnesium has high extractability compared to that of other metals, up to 80%.[1] A typical wort provides around 50–90 mg/L magnesium extracted from the grain.[1][8][18] However, a large portion of the measured magnesium may be bound to organic molecules, which greatly reduces the amount available to the yeast (grain-extracted magnesium has low bioavailablility).[5][4] The magnesium content of grain can vary widely, probably due to fertilizer usage.[13]
  • Salt additives - Brewers can enrich the magnesium level of the wort by adding brewing salts that contain magnesiumm, such as magnesium chloride or magnesium sulfate. Magnesium added from these salts will increase the amount available to be taken up by the yeast.

Effects of magnesium[edit]

In the context of brewing beer, magnesium has several important effects.

  • Improved pH control - Magnesium beneficially lowers the pH during mashing by precipitating with phosphates, proteins, and other compounds, although not as effectively as calcium because magnesium salts are much more soluble.[9][19][11][9][8]
  • Increased Maillard reactions - Magnesium promotes Maillard reactions between sugars and amino acids, which may or may not visibly increase beer color or have an impact on flavor (this has not been well studied).[13]
  • Improved fermentation - Magnesium ions are needed by many yeast enzymes, such as pyruvate decarboxylase.[4][9][8][19][1] In fact, magnesium is required for yeast growth and metabolism (fermentation).[1][5][19][20] The magnesium extracted from grain typically provides the minimum amount of magnesium needed to support fermentation, although the level is usually not optimal.[1][8][4][21] Additional magnesium can sometimes improve fermentation rate, including faster onset of fermentation, and can sometimes help improve yeast ethanol tolerance and improve the ability of yeast to ferment under stressful conditions, increasing sugar uptake and alcohol production.[10][4][1][5][22][23] Calcium ions inhibit magnesium absorption by the yeast,[1] and therefore magnesium addition may be especially useful in wort with a high calcium level (e.g. from the water or calcium salt additions).[5] Note that the response is strain-dependent.[5][6][22]
  • Improved yeast flocculation - Magnesium ions can positively influence flocculation, substituting for calcium.[1] This effect can be inhibited by the presence of metal-chelating agents (i.e. tannin additives) since magnesium is more sensitive to chelation than calcium.
  • Flavor - At the moderate levels typically found in wort, magnesium can enhance a beer's character by providing a mild sour or bitter astringency.[8][24][19][9][25][12] At excessive levels, the sour and bitter notes can become unpleasant and harsh.[8][26] These flavor effects appear to depend on a balance between the magnesium and calcium ions, since calcium can reduce the flavor impact of magnesium.[19]
  • Increased hop utilization - Magnesium increases humulone isomerization, which may contribute to its perceived bitter flavor effect.[13]

How to adjust the magnesium level[edit]

In order to ensure a good fermentation, the presence of some magnesium in brewing water is recommended.[10] While magnesium sulfate (e.g. Epsom salt) is a common traditional option, magnesium chloride is also a good option for adding magnesium if you would prefer to minimize the amount of sulfate. Magnesium content in yeast extracts (i.e. yeast nutrient products) can also improve the fermentation performance of yeast, although adding a magnesium salt might be more beneficial.[1] When considering the potential of magnesium to improve yeast fermentation performance, the concentration of wort calcium should also be taken into account.[1] Calcium competes with magnesium for uptake by the yeast, and any observed improvement may be related to the Mg:Ca ratio rather than the absolute concentration of magnesium.[1][5] See Water for our guide to adjusting water minerals and mash pH.

If the magnesium level in your tap water is too high, the only method to decrease the level is to purify the water with a reverse osmosis system. Yeast can theoretically absorb a maximum of 30–45 mg/L of magnesium during a typical fermentation, only mildly lowering the amount in the final beer.[4]

See also[edit]

References[edit]

  1. ↑ a b c d e f g h i j k l Gibson BR. 125th anniversary review: improvement of higher gravity brewery fermentation via wort enrichment and supplementation. J Inst Brew. 2011;117(3):268–284.
  2. ↑ Walker G, De Nicola R, Anthony S, Learmonth R. Yeast-metal interactions: impact on brewing and distilling fermentations. In: Proceedings of the Institute of Brewing & Distilling Asia Pacific Section 2006 Convention. 2006.
  3. ↑ 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.
  4. ↑ a b c d e f Saltukoglu A, Slaughter JC. The effect of magnesium and calcium on yeast growth. J Inst Brew. 1983;89(2):81–83.
  5. ↑ a b c d e f g Walker GM, Birch RM, Chandrasena G, Maynard AI. Magnesium, calcium, and fermentative metabolism in industrial yeasts. J Am Soc Brew Chem. 1996;54(1):13–18.
  6. ↑ a b Rees EM, Stewart GG. The effects of increased magnesium and calcium concentrations on yeast fermentation performance in high gravity worts. J Inst Brew. 1997;103(5):287–291.
  7. ↑ Kordialik‐Bogacka E, Bogdan P, Ciosek A. Effects of quinoa and amaranth on zinc, magnesium and calcium content in beer wort. Int J Food Sci Technol. 2019;54(5):1706–1712.
  8. ↑ a b c d e f g h i j Palmer J, Kaminski C. Water: A Comprehensive Guide for Brewers. Brewers Publications; 2013.
  9. ↑ a b c d e f Briggs DE, Boulton CA, Brookes PA, Stevens R. Brewing Science and Practice. Woodhead Publishing Limited and CRC Press LLC; 2004.
  10. ↑ a b c Ryder DS. Processing aids in brewing. In: Stewart GG, Russell I, Anstruther A, eds. Handbook of Brewing. 3rd ed. CRC Press; 2017.
  11. ↑ a b Eumann M, Schildbach S. 125th anniversary review: Water sources and treatment in brewing. J Inst Brew. 2012;118:12–21.
  12. ↑ a b Comrie AA. Brewing liquor—a review. J Inst Brew. 1967;73(4):335–346.
  13. ↑ a b c d Omari IO, Charnock HM, Fugina AL, Thomson EL, McIndoe JS. Magnesium-accelerated Maillard reactions drive differences in adjunct and all-malt brewing. J Am Soc Brew Chem. 2021;79(2):145–155.
  14. ↑ Kunze W. Hendel O, ed. Technology Brewing & Malting. 6th ed. VLB Berlin; 2019.
  15. ↑ Azoulay A, Garzon P, Eisenberg MJ. Comparison of the mineral content of tap water and bottled waters. J Gen Intern Med. 2001;16(3):168–175.
  16. ↑ Tackaberry R. Mineral content of drinking water, 100 USA cities. The Magnesium Web Site. 2002. Accessed online April 2024.
  17. ↑ Burlingame GA, Dietrich AM, Whelton AJ. Understanding the basics of tap water taste. J Am Water Works Assoc. 2007;99(5):100–111.
  18. ↑ Holzmann A, Piendl A. Malt modification and mashing conditions as factors influencing the minerals of wort. J Am Soc Brew Chem. 1977;35(1):1–8.
  19. ↑ a b c d e Taylor DG. Water. In: Stewart GG, Russell I, Anstruther A, eds. Handbook of Brewing. 3rd ed. CRC Press; 2017.
  20. ↑ White C. Yeast nutrients make fermentations better. White Labs. Accessed 2020.
  21. ↑ Walker GM. Role of metal ions in brewing yeast fermentation performance. In: Smart KA, ed. Brewing Yeast Fermentation Performance. 1st ed. Wiley-Blackwell; 2000:86–91.
  22. ↑ a b Bromberg SK, Bower PA, Duncombe GR, et al. Requirements for zinc, manganese, calcium, and magnesium in wort. J Am Soc Brew Chem. 1997;55(3):123–128.
  23. ↑ Walker GM. Magnesium as a stress-protectant for industrial strains of Saccharomyces cerevisiae. J Am Soc Brew Chem. 1998;56(3):109–113.
  24. ↑ Howe S. Raw materials. In: Smart C, ed. The Craft Brewing Handbook. Woodhead Publishing; 2019.
  25. ↑ Habschied K, Košir IJ, Krstanović V, Kumrić G, Mastanjević K. Beer polyphenols—bitterness, astringency, and off-flavors. Beverages. 2021;7(2):38.
  26. ↑ Fix G. Principles of Brewing Science. 2nd ed, Brewers Publications; 1999.
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