Calculating lactic acid additions

[dttk0009]

Hi everyone,

I've started taking water for mashing more seriously as I live in a city with relatively hard water with high residiual alkalinity, Berlin. As a result, I've bought 80% lactic acid to add to my mash water to bring the PH down to around 5.6.

After finding out my water profile is and calculating the results, I run into two problems:

1) I'm brewing a witbier fairly soon. Wheat tends to do nothing to lower the pH of my water, so I have to add more lactic to compensate. This brings me pretty much to the maximum I can add to my batch, which I'm using entirely in the mash water. I plan on adding 9ml to the mash water to bring it down to 5.6 pH. I wouldn't be able to add much to my sparge water after that.

2) When going by the 400 ppm rule for the taste threshold, I've read that 1ml/gallon is a good rule of thumb to go by. Does this count the total water used or simply the amount the final batch will be? For example, my batch size will be 21L, but total water needed is at 32.5L. That would land me at fairly different results.

Thanks!

 

[Silver_Is_Money]

I would just go ahead and make the batch. You may find that:

1) The lactic acid did not affect the flavor.
or 2) You actually like the flavor contribution of the lactic acid.

And if you both detect it and dislike it, then try using 10% phosphoric acid the next time.

 

[dttk0009]

I would just go ahead and make the batch. You may find that:

1) The lactic acid did not affect the flavor.
or 2) You actually like the flavor contribution of the lactic acid.

And if you both detect it and dislike it, then try using 10% phosphoric acid the next time.

Sounds good. I guess my main concern is that I can't really do much about reducing residual alkilinity of my sparge water, but I'm hoping it won't have too much of an impact on my beer overall.

 

[Silver_Is_Money]

Add lactic acid to your sparge water until it is at or below pH 6.0.

 

[mabrungard]

I'm not familiar with the water quality in Berlin, but I'm assuming that it has significant temporary hardness. If that's the case, pre-boiling the water and decanting off the clear water can significantly reduce both hardness and alkalinity. That pre-treatment can reduce the degree of acidification that you might need to employ.

 

[dttk0009]

I'm not familiar with the water quality in Berlin, but I'm assuming that it has significant temporary hardness. If that's the case, pre-boiling the water and decanting off the clear water can significantly reduce both hardness and alkalinity. That pre-treatment can reduce the degree of acidification that you might need to employ.

Oh damn, I had't even thought of that. I could definitely boil my sparge and mash water beforehand.

Is there a formula to calculate the change in alkilinity just by boiling? How long would I need to boil it for?

My water is at around 5.6°dH (or about 100ppm according to Google) residual alkalinity. Water pH at 7.6.

 

[ajdelange]

Residual alkalinity isn't of much interest. Alkalinity and hardness are. The general rule of thumb is that with alkalinity and hardness each expressed in mEq/L you can reduce the smaller to 1 and the larger will be reduced by the same amount. For example if you have hardness of 2.5 mEq/L and alkalinity of 3.5 boiling will remove 1.5 mEq/L hardness to bring it to 1.0 and will also reduce alkalinity by 1.5 lowering it to 2 mEq/L. This suggests an obvious strategy: increase the calcium to bring hardness up to at least equal the alkalinity. Then alkalinity will be reduced to 1 mEq/L which is about as low as you can practically get it this way. Note that in adding the extra calcium you will be adding more sulfate or chloride and you must be willing to accept that to use this strategy.

 

[dttk0009]

Residual alkalinity isn't of much interest. Alkalinity and hardness are. The general rule of thumb is that with alkalinity and hardness each expressed in mEq/L you can reduce the smaller to 1 and the larger will be reduced by the same amount. For example if you have hardness of 2.5 mEq/L and alkalinity of 3.5 boiling will remove 1.5 mEq/L hardness to bring it to 1.0 and will also reduce alkalinity by 1.5 lowering it to 2 mEq/L. This suggests an obvious strategy: increase the calcium to bring hardness up to at least equal the alkalinity. Then alkalinity will be reduced to 1 mEq/L which is about as low as you can practically get it this way. Note that in adding the extra calcium you will be adding more sulfate or chloride and you must be willing to accept that to use this strategy.

Thanks for the clarification! I've got quite a bit of calcium in my water already (3 mmo/l). I'll try to convert the data you've provided into the German standards to see where that lands me.

 

[ajdelange]

For the calcium hardness 3 mmol is 6 mEq. That is a lot of calcium for sure. You can potentially drop 5 mEq/L calcium and alkalinity by boiling (if the alkalinity be 6 or more). If it be less then you should be able to decarbonate down to 1 = 50ppm as CaCO3 = ? dH.

 

[dttk0009]

For the calcium hardness 3 mmol is 6 mEq. That is a lot of calcium for sure. You can potentially drop 5 mEq/L calcium and alkalinity by boiling (if the alkalinity be 6 or more). If it be less then you should be able to decarbonate down to 1 = 50ppm as CaCO3 = ? dH.

I found a few conversion tables last night and calculated around a bit.

Pre-boil looks like this:
Alkalinity - 187.2 mg/l
Calcium - 120.7 mg/l

Post-boil looks like this:
Alkalinity: 35.7 mg/l
Calcium: 61 mg/l (1.52 mmol)

Conversions are based on forumulas for brew water I found in German. Measuring alkalinity seems to be an American thing as here they go by hydrogen carbonate.

50ppm CaCO3 should be ABOUT 2.8 °dH HCO3-.

According to my other sources, a rolling boil of 30 minutes can reduce the HCO3- °dH of the water to about 2, which is how I ended up with a lower alkalinity calculation than 50ppm (mg/l). Seems to be in the ballpark, though.

If you're curious, I found all the conversions and calculations here:
http://braumagazin.de/article/von-der-wasseranalyse-zum-brauwasser/

Thanks again for the input. I should have paid more attention in chemistry class.

 

[ajdelange]

Measuring alkalinity seems to be an American thing as here they go by hydrogen carbonate.

50ppm CaCO3 should be ABOUT 2.8 °dH HCO3-.

Should be exact. 50 ppm as CaCO3 is exactly 1 mEq/L. They may go by hydrogen carbonate in Germany but they determine it by measuring alkalinity with the option being ion chromatography which I doubt your lab is using. In the US we (unfortunately) convert the bicarbonate found to the amount of CaCO3 required to produce the HCO3- observed when it is dissolved by CO2. Since CO2 + CaCO3 + H20 --> Ca++ + 2HCO3- its clear that each mole of HCO3- (which takes one mole of acid to destroy in the alkalinity titration) came from 1/2 mole of CaCO3 of molecular weight 100 hence we multiply the acid used in the titration by 50. In the German system (equally or perhaps a bit more unfortunate - our lives would be so much easier if they just gave us the mEq/L from the titration) the dH number is (I believe) the amount of CaO behind the bicarbonate. i assume they approach it as CaO + 2H2CO3 --> H20 + 2HCO3- +Ca++ in which each mol of bicarbonate comes from half a mole of CaO of molecular weight 56.0774 so the acid consumed would be multiplied by 28 and 1 mEq/L alkalinity would be 28 ppm as CaO. But as 1 mEq alkalinity is 2.8 °dH it is clear they divide alkalinity as CaO by 10 to get dH.

You can, of course, get the same answer by looking at the hardness. Put 1/2 mmol (28 mg) of CaO in 1 L water

CaO + H2O --> Ca++ + 2(OH)-

and you have 1 mEq/L Ca++ ion from 28 mg CaO and the strength is 28 mg/L as CaO or 2.8 °dH

 

[dttk0009]

Thanks again for the thorough replies and explanation. I'll be honest, I have a hard time digesting some of the contents of your post, but it's good to know that my basic calculations were accurate, feels like I'm gaining knowledge about an interesting subject, especially one that can benefit the quality of my beer.