Editing Magnesium

[[File:Magnesium.png|right|alt=Magnesium periodic table emblem|link=]]
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.

'''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 ==
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.<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> 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%.<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 ==
In the context of brewing beer, magnesium has several important effects.
* '''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/>
* '''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 ==
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 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/>

== See also ==
* [[Water]] - Expert guide to adjusting water minerals
* [[Magnesium chloride]] - Brewing salt
* [[Magnesium sulfate]] - Brewing salt

== References ==
[[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
}}