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Lactic acid calculations

http://www.thebrewingnetwork.com/forum/viewtopic.php?f=6&t=32206

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Lactic acid calculations

Posted: Tue Sep 16, 2014 11:10 pm
by SweBrew
Hi yoaaal i´m not 100% sertain how one calculate lactic ions. I have an 80% lactic acid blend in a bottle (store bought). Whats the concentraton of 1N solution? is it 88%? or a 100%
Is 1mEq/L the same as 1ml/L? and if 1mEq/L contributes with 89 ions, do 1ml in 10L water contribute with 8,9 lactic ions?

How many lactic ions do an 80% blend contribute with per 1ml/L


I think iv over did it one time with a Saison :pop

Usualy i just use 2ml of lactic acid for a 5gal brew, 1 to correct the mash pH in light beers and 1 to the spage water. Iv read the water book over and over, listened to the water show, used salts for a couple of years with great results. I feel like it´s the one thing that i don´t realy grasp at the moment this lactic contribution thing.

Re: Lactic acid calculations

Posted: Wed Sep 17, 2014 6:01 am
by jonboris
I'm not sure anyone can answer that correctly without knowing your water and your grain bill, unfortunately.

Have you gotten a water report for your area?

Re: Lactic acid calculations

Posted: Wed Sep 17, 2014 8:46 am
by SweBrew
jonboris wrote:I'm not sure anyone can answer that correctly without knowing your water and your grain bill, unfortunately.

Have you gotten a water report for your area?

But isn´t the ion contribution the same (initially) for one normal solution of 1mEq/L regardless the starting water? In the water book it reads: it contributes 89 mg/L of lactate ions per mEq of acid when added to water.
And for now i don't want to calculate with the reaction, so pretend i use dealkalized water.


And for the fun of it!
my starting water: Calcium Magnesium Sodium Chloride Sulfate Alkalinity (HCO3 ppm)
24 3,7 10 13 36 52

Re: Lactic acid calculations

Posted: Wed Sep 17, 2014 1:36 pm
by jonboris
My bad, I sped through your initial question re ion contribution and centered in on the acid addition to mash and sparge water, and it made my eye twitch.

I can't answer your questions about ion contributions and equivalencies.

What I CAN do is enter your water profile (assuming pH 8 ) and a theoretical saison grain bill into Bru'n Water, and tell you that 1ml of 80% lactic acid solution would bring 4.5gal of sparge water down to pH 6, and 1ml into 3.5gal mash water with no other salt additions would bring your mash pH with that specific grain bill down to pH 5.6

I did get curious from your questions, so I checked out braukaiser's site, in the mash pH control section, found this:
"To convert Eq to an actual amount of acid/base its molar weight, number of hydrogen ions donated/absorbed and its concentration needs to be known. Lactic acid for example has a molar weight of 90 g/mol. Above a pH of 5 almost all its molecules donate 1 hydrogen ion. This means 90g 100% lactic acid contribute about 1 Eq acid. The lactic acid we commonly use has a concentration of 88% by weight and 1 Eq of that weighs 102 g. 1 mEq weighs 0.102 g."

I just hosed away an hour at work going down the rabbit hole, and for that, I am forever grateful!

Re: Lactic acid calculations

Posted: Wed Sep 17, 2014 10:48 pm
by SweBrew
I know how much lactic acid i need to bring down the pH, i use water calculation spreadsheets, the thing i don´t grasp is how many ions it contributes.


My question remains: how many lactic ions do an 80% blend contribute with per 1ml/L

Re: Lactic acid calculations

Posted: Thu Sep 18, 2014 11:11 am
by Klickitat Jim
I think ions are very very small so probably it's a lot. I'm curious why it's important to know how many.

Re: Lactic acid calculations

Posted: Thu Sep 18, 2014 10:12 pm
by SweBrew
Klickitat Jim wrote:I think ions are very very small so probably it's a lot. I'm curious why it's important to know how many.


I want to know the amount of ions so i can fine tune the recipe and dont contribute with more than whats detectable, in the water book it says 400ppm is a threshold but some can taste it even sooner.
I want to know dag nabit....

Re: Lactic acid calculations

Posted: Fri Sep 19, 2014 10:27 am
by Klickitat Jim
Got it. I use lactic to prep for proper ph and I use brewer's friend. What I found is that I only need to use half of what it suggests. I've dumbed it down now to 1ml in mash and sparge for light color, one on sparge for amber/brown, and none for black. Works for me.

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