Calcium Lactate Buffers in the mash: Water chemistry Qs time...

[brewchampion]

Im trying to work out water chemistry on the Ca Lactate Ph buffer powder.
Not allot of info out there.,
Worked out I shouldn't add more than 3 tsp per 20l unless It may affect flavour..
http://braukaiser.com/blog/blog/category/science/brewing-water/

But the buffer reaction equilibrium.... Hmmm.
I imagine it buffers the Bicarbonate in an alkali mash , but does it react to CO2 taking it out ?
And in acidic stout mashes, how does the CaLa buffer the roasty mash? Its lacttic acid in the roast malt too isnt it?

Trying to get a feel of how this buffer is affecting my water chemistry.
Any water chem geeks out there?

MHB ?

 

[MHB]

Hi
I have been working with calcium lactate for a couple of years, the first thing is to note that the Braukaiser article is talking about 'Lactic Acid" that bares as much relationship to Calcium Lactate as does Sulphuric acid to Calcium Sulphate, I'm not suggesting large additions of Lactic Acid nor of Sulphuric, for very similar reasons - they are unnecessary.

Calcium Lactate and Lactic Acid are a conjugate pair, and form one of the most powerful buffers known, at 150 Moles of CaLac : 1 Mole of Lactic Acid it will buffer at about 5.2pH. not all the acidity in dark mashes comes from Lactic Acid - but a big hunk of it will.

What got me started working with CaLac was the was the way it is made, you react chalk and lactic acid and as ~90% of the acidity in most mashes comes from naturally occurring Lactic Acid on the malt, I figured it was the pathway insoluble chalk came into play.

So far I am very happy with the results, its a very easy way to adjust the Ca levels in a mash and to control the pH without having to get too detailed with your research into water chemistry.

I believe Brewman has it if you want to have a play around.
Mark

 

[brewchampion]

Tx for the detailed reply.

I read Kais report as though he had used Ca Lactate
" Both calcium lactate and sodium lactate tasted very similar in water which shows that sodium doesn’t necessarily lead to a salty taste. I decided to go with calcium lactate since calcium is generally the dominant cation in alkaline waters."

So the Ca and the Lactate are conjigate pairs.
If the lactate does not reduce, then it stays in solution as... lactic acid? So would impart flavour in high doses?

 

[MHB]

No you are rather missing the point. Buffer chemistry is fairly involved, there is a good primer on Braukaiser well worth reading.
But the buffer is the relationship between CaLac and Lactic Acid, you can Google it up you will find lots of calculators on line that well help you with the numbers, its about 20 yeast since I looked at ksp and pH, when I was playing around with the numbers I got a friend with a PhD in Chemistry to help.

Calcium lactate disassociates into Calcium ions and Lactate ions, not the same as Lactic Acid, same way Calcium Sulphate disassociates into Calcium and Sulphate ions not Ca and Sulphuric acid. can take a bit of getting you head around.

Or to give a common example, when you dissolve common salt (NaCl) in water you get Sodium ions and Chloride ions not Chlorine gas.

Do read the primer on buffers in Braukaiser.
Mark

 

[brewchampion]

Tx for trying to kelp my understanding Mark.


So lactic acid... C2H4OHCOOH , in solution, loses its proton at 3.86 pKa from the carboxyl group becoming H+ and the lactate ion CH3CH(OH)COO−
But its different to aqueous Calcium Lactate ( [Ca]2 + 2[CH3CH(OH)COO]− )
because Calcium has a greater affinity than a Hydrogen anion.

OK, im getting somewhere....

The Braukaiser wiki is down right now, so I cant google that primer.
And ive been looking for some time for a formula for this buffer , particularly on the alkali side of things.

So if I get where your going, we are looking at it buffering with only these ions.....


[Ca2+] 2[CH3CH(OH)COO− ] 2[H+] 2[OH-]

Or are there more ions involved with both acid and alkali mash buffering?

 

[MHB]

Malt has a pretty reasonable buffering capacity in itself, it is or can be a really complex system.
Like I said the primer on Braukaiser is really good, hope its back up soon.
The book "Water" is also excellent.

Products like 5.2 by five star is a phosphate buffer, probably a combination of di and tri sodium phosphate
There are lots of other buffers available, but most of them are going to be a combination of an acid and a salt of that acid
It helps to remember that H+ and OH- pretty much cancel our and leave you at neutral (7pH) pH being the inverse decimal log of H+ activity

Mark

 

[brewchampion]

OK, I diddnt know the 5.2 was phosphate based.
So do you think the added lactate adding gets metabolised by yeast or stay in salt form?

 

[MHB]

None of the above, once dissolved all salts are present as ions.
There is already plenty of Lactate ions in the mash so a little more isn't I suspect going to be noticeable, Calcium is consumed during mashing and wort boiling, more is used by the yeast, it's important in all stages of brewing.

I think what you need to do is to go back a few steps, learn some more of the basics of water chemistry, that will put you in a better position to understand buffering and the role various salts play in brewing. There is lots of good information on the www, If I recall there is a good primer on the BYO website among others.

The subject is a bit too complex to go at in bits, you need a pretty solid basis in inorganic chemistry and a systematic approach to water chemistry for it to be useful.

Mark