Argument against magnesium sulphate?

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
pcrussell50

#1: Post by pcrussell50 »

As an acolyte of Dr. Pavlis' water guidelines, I use only sodium and potassium bicarbonate added to distilled water in my espresso machines. BUT there seem to be a lot of recipes out there that call for epsom salts, (magnesium sulphate). I know magnesium sulphate is not specifically the same as magnesium carbonate (scale), but isn't there at least some scaling or corrosion risk in using it? And why is it used? Taste?

I'm trying to explain to someone in another thread why I only use sodium or potassium bicarb and NOT epsom salt, and I need a little help.

-Peter
LMWDP #553

CwD

#2: Post by CwD »

I think only having carbonate hardness is a pretty horrible idea, honestly. The general hardness doesn't have to come from magnesium sulfate, there are other sources like magnesium chloride, calcium chloride, calcium citrate, etc. But just using potassium bicarbonate is a great way to round off any interesting bits of the coffee. I suppose if you really despise even the slightest hint of acid it could be fine, but I'd rather need to descale every now and then than put up with lopping off everything that makes a coffee good.

Weber Workshops: tools for building better coffee
Sponsored by Weber Workshops
RyanJE

#3: Post by RyanJE » replying to CwD »

I wonder if this is less of an issue for someone who typically likes darker roasts and doesn't want acidity anyway. But, yes, wouldnt that high of a level of buffer also buffer all the good acidity in lighter roasts?
I drink two shots before I drink two shots, then I drink two more....

OldNuc

#4: Post by OldNuc »

I miss Dr. Pavlis more every day. A proper explanation of what occurs in the extraction process and the consequences of doctoring the water with left over chemicals from you old Gilbert Chemistry set requires someone with a great deal of knowledge regarding these interactions.

If the coffee tastes bad then you should fix the coffee and/or extraction process not doctor the water. A commercial establishment who is buying coffee in multiple 150lb lots is more or less forced to tweak the water to maintain their product consistency to the customer.

Distilled water produces the true taste of the coffee. The addition of a minor amount of sodium or potassium bicarbonate is primarily for the protection of the copper components in the brew path.

User avatar
hankbates

#5: Post by hankbates »

Rich, I couldn't agree with you more. I think that if Robert Pavlis were still with us, he might have responded identically.

I would like to add that it is a very bad idea to promote the use of chlorides (and even worse, chlorides in an acidic environment) in any boiler, home or industrial.
CwD wrote:I think only having carbonate hardness is a pretty horrible idea, honestly. The general hardness doesn't have to come from magnesium sulfate, there are other sources like magnesium chloride, calcium chloride, calcium citrate, etc. But just using potassium bicarbonate is a great way to round off any interesting bits of the coffee. I suppose if you really despise even the slightest hint of acid it could be fine, but I'd rather need to descale every now and then than put up with lopping off everything that makes a coffee good.
Chlorides can cause both catastrophic pitting and/or stress corrosion cracking of copper, brass or stainless steel. If you want to have chlorides in your coffee machine and care about its life, make sure it is made of titanium.

pcrussell50 (original poster)

#6: Post by pcrussell50 (original poster) »

Great info guys...

So allow me to summarize what I've take from this so far about the pro's and con's of magnesium sulphate in espresso water:

1) it brings out acidity (which I DO like, by the way)
2) at the expense of increased scaling tendency

I've been away from the lever group for a while... Youys are taking a forboding tone about Robert. Is he... On a sabbatical (hoping)? Or... Worse... (I fear) :(

-Peter
LMWDP #553

OldNuc

#7: Post by OldNuc »


Aida Battle: Indigo Reserve from world renowned Finca Kilimanjaro in El Salvador
Sponsored by Aida Battle
pcrussell50 (original poster)

#8: Post by pcrussell50 (original poster) »

76. Far too young. :(

What a massive loss for our community.

-Peter
LMWDP #553

CwD

#9: Post by CwD »

OldNuc wrote: Distilled water produces the true taste of the coffee. The addition of a minor amount of sodium or potassium bicarbonate is primarily for the protection of the copper components in the brew path.
Nah, that would be grabbing a handful of beans and chewing them.

It's no less "true" coffee just because you're using water with enough ions in it to actually be capable of a complete extraction.

User avatar
homeburrero
Team HB

#10: Post by homeburrero »

I also miss Dr Pavlis, am a fan of his keep it simple approach.

I guess that he might argue against the addition of magnesium sulphate simply by saying that if you don't need it, why add it.

There are some arguments against it -
The magnesium ion in high concentration and the presence of carbonates might produce some precipitates or deposits, and sulphate ion in the presence of calcium might produce troublesome calcium sulphate deposits (which don't dissolve in descaling solutions). In addition, the sulphate ion might increase corrosion risk (although not nearly as much as chloride ion would.)

To counter the popular belief that magnesium in the water would be expected to enhance flavor extraction, Dr. Pavlis often would point out that coffee is already high in magnesium, and it makes little sense that a small amount in the incoming water would make much difference given the relatively huge amount coming from the coffee itself in the liquid flowing through the puck.

I know that lots of folks with sophisticated palates have found taste improvements when using brew water with higher calcium and/or magnesium content. But the conservative approach for DIY water makers would be to first try the rpavlis water*, and if the taste you want isn't there, then maybe experiment carefully with harder water.

P.S.
My understanding (not a real chemist) is that magnesium ion in the presence of carbonates does tend to precipitate as magnesium hydroxide and magnesium carbonate when the boiler pressure and temperature increases, but not to the same degree and in the same way as calcium carbonate. People using the relatively hard Matt Perger recipe, which has 2 mEq/L magnesium sulfate and 1 mEq/L bicarbonate (100:50 in CaCO3 equivalents) have reported seeing no scale in their steam boilers. Many re-mineralization and softening products (for example the BWT bestmax premium) on the market tout the advantage of magnesium as supposedly flavor enhancing, but without introducing scale problems.


* Below is a nice quote from R. Pavlis ( see Water quality? ) that succinctly describes his recipe:
rpavlis, in March 2016 post, wrote:In my area of ridiculously polluted tap water I simply buy jugs of distilled water from the grocery stores and add potassium bicarbonate to it like brewers do to their beer and wine. With medium light roast I would recommend 100mg/litre. If roasted into the second crack I would recommend less, perhaps 50mg/litre or less. The thing is one can adjust to taste. You can adjust amount up and down. No scale will ever form.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h