Sauergut acid percentage estimate question

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TheMadKing

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So I don't know enough about chemistry to know if this is valid or not.

I'm trying to estimate the percentage of lactic acid in my Sauergut so that I can dose my beer accordingly, but I'm really lazy and don't want to buy a titration kit to measure it properly.

So I plugged my Sauergut recipe and volumes into Bru'nwater and I measured the pH with a calibrated meter at the end of the minimash and immediately after adding 1mL of 88%lactic acid to drop the pH for the lactobacillus. I measured a pH of 4.9.

Today I took a second pH reading of 3.2 immediately before brewing.

So I plugged all my numbers back into Bru'nwater including 1mL of 88% lactic, and then used guess and check to see how many ml of 100% lactic acid it would take to reach a pH of 3.2

It estimated 3.2mL (interesting coincidence) and a have 2500mL of total Sauergut, so that puts me at approximately 0.13% lactic acid by volume.

That seems low but I then plugged my helles recipe into Bru'nwater and used a mixture of 1L of 0.13% lactic acid and 3mL 88% lactic acid to target a pH of 5.4.

I just measured the mash pH and it's 5.2 indicating that the acid % estimate of the Sauergut was indeed a little low.

So did I get lucky? Or is this a valid method for creating a gross estimate of Sauergut acid content without titration?
 
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You are assuming that sauergut is a solution of lactic acid in water. It isn't. It is lactic acid dissolved in wort. Thus it is a mixture of dozens of buffers only one of which is lactic acid and all the others of which are buffering compounds found in wort. Thus, were you to titrate sauergut you would find the curve different in shape from that of the titration curve for a lactic acid solution in water. Note that as I have never actually titrated sauergut this statement has to be taken as an educated opinion rather than a demonstrated fact unless you can find data from someone else who has titrated sauergut.

Given that the curves are different shapes there is no general equivalence number that can be offered comparing sauergut and lactic acid. The equivalence depends on the ending pH of the blend of sauergut or lactic acid and whatever it is you are acidifying with it. Now it may turn out that that the equivalence curve is flatter than I am implying here in which case you might make a statement to the effect that 1 L of sauergut is equivalent to x mL of lactic acid of the typical range of mash pH's and y mL of lactic acid over the typical range of kettle pH's.
 
You are assuming that sauergut is a solution of lactic acid in water. It isn't. It is lactic acid dissolved in wort. Thus it is a mixture of dozens of buffers only one of which is lactic acid and all the others of which are buffering compounds found in wort. Thus, were you to titrate sauergut you would find the curve different in shape from that of the titration curve for a lactic acid solution in water. Note that as I have never actually titrated sauergut this statement has to be taken as an educated opinion rather than a demonstrated fact unless you can find data from someone else who has titrated sauergut.

Given that the curves are different shapes there is no general equivalence number that can be offered comparing sauergut and lactic acid. The equivalence depends on the ending pH of the blend of sauergut or lactic acid and whatever it is you are acidifying with it. Now it may turn out that that the equivalence curve is flatter than I am implying here in which case you might make a statement to the effect that 1 L of sauergut is equivalent to x mL of lactic acid of the typical range of mash pH's and y mL of lactic acid over the typical range of kettle pH's.

Thanks AJ, I knew I had to be missing something. So expressing the buffering power of Sauergut as a % lactic acid solution at all is erroneous unless I build a titration curve table and come up with an equation for the best fit line to estimate equivalency

My final end of boil pH after the flame out Sauergut addition was low at about 4.7 and I ended up adding 3g of baking soda to bring it back closer to 5. After the baking soda addition my pH was 4.9 and I was at 42ppm sodium, so I accepted that and I'm letting it ferment.

Based on your reply and my ending results, I would be better served by overcoming my laziness and just buying a titration kit next time, or doing a mini mash of my beer to directly measure the effect of the Sauergut and then scale it up.
 
Thanks AJ, I knew I had to be missing something. So expressing the buffering power of Sauergut as a % lactic acid solution at all is erroneous unless I build a titration curve table and come up with an equation for the best fit line to estimate equivalency

My final end of boil pH after the flame out Sauergut addition was low at about 4.7 and I ended up adding 3g of baking soda to bring it back closer to 5. After the baking soda addition my pH was 4.9 and I was at 42ppm sodium, so I accepted that and I'm letting it ferment.

Based on your reply and my ending results, I would be better served by overcoming my laziness and just buying a titration kit next time, or doing a mini mash of my beer to directly measure the effect of the Sauergut and then scale it up.
Can you forward me the details of your batch?

We have some experience reverse engineering the acid % of the Sauergut by using trial and error.
 
Can you forward me the details of your batch?

We have some experience reverse engineering the acid % of the Sauergut by using trial and error.

1lb Pilsen malt into 0.74 gallons of water, mashed at 149F for 60 minutes for a OG of 1.040. I added 1 ml of 88% lactic acid after the mash to drop the pH to 4.9. Then I raised the temp to 180F to pasturize, cooled to 118F and pitched 4oz of fresh Pilsen malt.

I held it at 118F for 36 hours before it went into my Helles mash. The pH of the Sauergut right before pitching was 3.2 and it tasted like tart fresh grain with a hint of citrus.
 
1lb Pilsen malt into 0.74 gallons of water, mashed at 149F for 60 minutes for a OG of 1.040. I added 1 ml of 88% lactic acid after the mash to drop the pH to 4.9. Then I raised the temp to 180F to pasturize, cooled to 118F and pitched 4oz of fresh Pilsen malt.

I held it at 118F for 36 hours before it went into my Helles mash. The pH of the Sauergut right before pitching was 3.2 and it tasted like tart fresh grain with a hint of citrus.

What I meant was this: give me the info from the Helles batch along with the acid % you used for the Sauermalz. I should be able to work backwards to get the actual acid percentage based on your predicted versus actual pH of the batch.

Are you making Sauergut on a batch to batch basis?
 
What I meant was this: give me the info from the Helles batch along with the acid % you used for the Sauermalz. I should be able to work backwards to get the actual acid percentage based on your predicted versus actual pH of the batch.

Are you making Sauergut on a batch to batch basis?

Ah sorry I misunderstood

Yes, I don't brew often enough to justify a reactor so I make single batches using an instant pot (multifunction electric cook pot)

My Helles recipe is:

6lb Pilsen
2lb Vienna
1lb Munich
4oz melanoidin

I didn't use Sauermalz

I BIAB and I made a 6 gallon batch so I mashed in with 9.3 gallons of water at 105 for an acid rest. I added the Sauergut at mash in along with 3.2 mL of 88% lactic acid and my mash pH 10 mins after mashing in was 5.2 at 68F.

My tap water is essentially identical to Pilsen water.

I reverse engineered the acid percentage based off of the actual mash pH this morning and got closer to 1%

But as AJ said above, this is an equivalency to lactic acid in water not a measurement of actual acid content since there are other buffers in play in wort. So yes it's possible to show an equivalency after the fact on a case by case basis, but this equivalency will mean nothing for my next recipe. Especially since I make Sauergut in single batches.
 
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This may seem a silly question, coming from someone who’s never used sauermalz, which I believe is also called acid malt. What advantages does it have over using 88% lactic acid instead?

From what I’ve read the acid amounts across maltsters and batches varies a lot. As opposed to using a measured amount of lactic acid, which in my mind is fairly consistent.
 
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This may seem a silly question, coming from someone who’s never used sauermalz, which I believe is also called acid malt. What advantages does it have over using 88% lactic acid instead?

From what I’ve read the acid amounts across maltsters and batches varies a lot. As opposed to using a measured amount lactic acid, which to my mind is fairly consistent.

I misspoke in the post above. I was trying to say Sauergut. @TheMadKing and I were and are talking about Sauergut.

Since you mentioned it, however, I use Sauermalz because of the fact that it’s a grain and I don’t have to worry about measuring acids. I just plop it in and grind it with the grain bill and call it a day. The new titration based model has made Sauermalz much more reliable as well. The titration data for Sauermalz, though limited, is pretty consistent.
 
I misspoke in the post above. I was trying to say Sauergut. @TheMadKing and I were and are talking about Sauergut.

Since you mentioned it, however, I use Sauermalz because of the fact that it’s a grain and I don’t have to worry about measuring acids. I just plop it in and grind it with the grain bill and call it a day. The new titration based model has made Sauermalz much more reliable as well. The titration data for Sauermalz, though limited, is pretty consistent.

I used a guesstimate of 0.13% lactic acid for my Sauergut based on my calculations in the original post.

That seemed low to me at the time, and it was indeed low but I used it instead of traditional ballpark of 0.8%, which was a mistake.
 
I used a guesstimate of 0.13% lactic acid for my Sauergut based on my calculations in the original post.

That seemed low to me at the time, and it was indeed low but I used it instead of traditional ballpark of 0.8%, which was a mistake.

Since you are making it and using right away, 0.8-1.2% is a good range 0.13% explains why you were low v
 
This may seem a silly question, coming from someone who’s never used sauermalz, which I believe is also called acid malt. What advantages does it have over using 88% lactic acid instead?

From what I’ve read the acid amounts across maltsters and batches varies a lot. As opposed to using a measured amount lactic acid, which to my mind is fairly consistent.

I use Sauergut because of the flavor addition since it requires a litre+ of volume vs a few mL. I have used 88% lactic acid for years, but I'm currently exploring the flavor benefits of this method in German lagers. I do use 88% lactic in every other style.
 
I held it at 118F for 36 hours before it went into my Helles mash. The pH of the Sauergut right before pitching was 3.2 and it tasted like tart fresh grain with a hint of citrus.

You might try holding your sauergut at temperature for a bit longer, say 3 to 5 days to get the best acid content. Also seems to work a little better if you drop the temp to around 100f after the first 24 hours. Anyway that's what works for me.
 
You might try holding your sauergut at temperature for a bit longer, say 3 to 5 days to get the best acid content. Also seems to work a little better if you drop the temp to around 100f after the first 24 hours. Anyway that's what works for me.

Doesn’t the high temperature help to keep other less desirable forms of lactobacillus from growing? I thought that was the reason for keeping it at 118F, to help select for a specific subspecies
 
Doesn’t the high temperature help to keep other less desirable forms of lactobacillus from growing? I thought that was the reason for keeping it at 118F, to help select for a specific subspecies

Yes true but the LAB has a reduced tolerance to low pH at higher temperatures. So by lowering the temperature after they get a good start you will end up with a greater amount of acid.
 
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