[Tristan]

My water only has 5 ppm of Magnesium.  I typically dilute with 40-60% RO water when I brew anything lighter than 10 SRM and also for any lagers.  That means my magnesium content is even less.  The last two beers I brewed were identical to beers brewed in the past except I added 2-3 grams of magnesium sulfate to bump up my magnesium to 10 PPM.  One was a Munich Helles and the other was a APA.  They both fermented like "gangbusters" in comparison to previous batches of lagers and ales.

Tonight, I just finished Continental Pilsener by David Miller.  He states that under no circumstances should a brewer add magnesium to his brewing liquor.  However, I've seen advice to the contrary.  For example, Kai, who has a great grasp on water chemistry, lists recipes for building water profiles on his website which include magnesium sulfate as well as the usual suspects.  Despite hearing that a sufficient quantity of magnesium will come from the malt itself, John Palmer states brewing liquor should contain > 10 PPM of magnesium.

What are your thoughts?

[tschmidlin]

It's an important enzyme co-factor and could explain why your beer fermented so well.

Is is also a diuretic, so you don't want too much.

I don't know how much Mg is in malt, it probably depends on the barley variety and where it was grown.

[mabrungard]

Mg is available from the malt, but I have a paper that researched yeast performance and they confirmed that yeast flocculation performance is significantly enhanced with at least 5 ppm Mg in the wort.  It would seem to me that this researcher's results would have already had Mg in it if they used a malt wort, but I don't remember if it did.

This doesn't provide definitive guidance on Mg's effect of yeast growth and performance, but I believe that it doesn't hurt as long as the Mg concentration is kept moderate.  You will start to have taste impact at concentrations of 30 ppm.  Therefore, I recommend that a preferred Mg range is 5 to 30 ppm in the mash and sparging water. 

I am still impressed with Dave Miller's Homebrewing Guide, even though its over 15 years old.  The Continental Pilsener book is another situation and aimed at a particular style.  In the Homebrewing Guide, he does say that 10 to 20 ppm is desirable and the max is 30 ppm.   I agree that in that style, it has delicate flavors that would probably be affected by the harshness that Mg might apply.  I agree with the recommendation for that style, but not in general. 
 

[denny]

What are your thoughts?

My thoughts are that the Miller books are extremely dated and there's much better info available these days.

There's a bit of info on Mg (among other nutrients) in Tobias Fischborn's 2009 NHC presentation...

http://www.ahaconference.org/wp-content/uploads/presentations/2009/Tobias-Fischborn-NHC2009-Yeast%20nutrition.pdf

[Tristan]

Thanks Denny!  Fascinating material!

[tomsawyer]

I usually use a little of Northern Brewer's nutrient blend in my starters and ferments.  I'll have to double check what they put in it but I'm ifarly sure it'll have zinc, biotin and amino acids.  Less certain about Mg.

[Tristan]

I've been using the LD Carlson yeast nutrient from the local B&M and it doesn't have an ingredient list.  A Google search yielded no usefully info.  I might have to order some Wyeast or White Labs nutrients that contain zinc after reading that PowerPoint Denny posted.

[a10t2]

This doesn't provide definitive guidance on Mg's effect of yeast growth and performance, but I believe that it doesn't hurt as long as the Mg concentration is kept moderate.  You will start to have taste impact at concentrations of 30 ppm.  Therefore, I recommend that a preferred Mg range is 5 to 30 ppm in the mash and sparging water.

Based on the only controlled study I've seen on it, there isn't an impact on fermentation performance until you get over 200-300 ppm anyway. I'll try to dig up the paper when I get home.

[Kaiser]

Tristan, my insight into a lot of things brewing keeps evolving. I now think there is no need to add Mg since the malt brings enough into the wort. This is why I have been skipping Mg salts lately. 

Kai

[mabrungard]

I just listened to Palmer's Brew Strong series on brewing water this week.  There were some minor errors in what John mentioned in his shows, but not too bad.  One of the things that John did mention was that his co-author Colin Kaminsky has found that minor Mg additions were very beneficial to flavor in some styles. 

In addition, Tobias Fischborn with Lallemand (the yeast people) specifically called out Mg as a desirable nutrient for yeast. 

While I agree that malt does supply some Mg, I've seen too many references that indicate small Mg additions can be desirable to the overall performance and flavor of beer.  The malt had to be adding some Mg for those other brewers, so I suggest that a minimum of 5 ppm of additional Mg should be included in any brewing water (ie, minimum brewing water Mg content should be 5 ppm).  Brewers should be careful and recognize that the desirable Mg range is small and going above 30 ppm is probably going to negatively affect their beer.

Enjoy.

[Tristan]

Thanks for all the responses!  It seems like malt adds a high amount of magnesium to the equation.  It leaves me to wonder if epsom salt additions are more critical in a beer with a high percentage of adjuncts as these would dilute the magnesium content in the wort.

One of the things that John did mention was that his co-author Colin Kaminsky has found that minor Mg additions were very beneficial to flavor in some styles.  

Thanks!  I caught the comment on Colin adding epsom salt to his porter.  I'm going to take your advice on having minimum 5ppm magnesium going forward.

I tasted a sample of my Munich Helles (I added 3 grams to my HLT to get 10ppm magnesium for the brewing liquor).  I didn't taste anything odd or out of place.  For a very young beer it tasted wonderful!

[a10t2]

I forgot to post the link to the paper: http://www.scientificsocieties.org/jib/papers/1997/1997_103_5_287.pdf

The effects they saw, even at 500 ppm Mg, were so minor that I don't think there's any point in adding Mg solely for yeast health or performance.

[Tristan]

I forgot to post the link to the paper: http://www.scientificsocieties.org/jib/papers/1997/1997_103_5_287.pdf

The effects they saw, even at 500 ppm Mg, were so minor that I don't think there's any point in adding Mg solely for yeast health or performance.

Thanks, that was an excellent read.

[johnf]

One of the things that John did mention was that his co-author Colin Kaminsky has found that minor Mg additions were very beneficial to flavor in some styles.

Given that all barley malt wort will likely have 100+ ppm Mg with non from the water, at first glance it seems unlikely that a marginal few ppm would make much difference to flavor.

Assuming Colin did not add elemental Mg, how does he know the flavor impact was not from the anion? How does he know it exists? I guess I need more than an anecdote to accept such a huge violation of Occam's Razor.

[Kaiser]

could it be that the flavor came from the sulfate and not the added Mg?

Kai