Bruin Water-Adding Measured Mash pH-Need Help for Brew Today

[Jiffster]

I am using Bru'n Water to build my water profile for a Porter I am brewing today.

There is a thread on this that I would love help on of you can:

https://www.homebrewtalk.com/showthread.php?p=7662505#post7662505

At a minimum, I need to know how to add the measured mash pH in Bru'n Water.

I did a test mash yesterday and the measured pH was .19 higher than Bru'n Waters estimate. 5.31 estimated vs 5.46 measured (5.45 at 10 min, 5.46 at 20 min)

So now when trying to add Calcium Chloride, Baking Soda and Gypsum to build my profile, I don't really know if I'm being accurate.

Since my measured pH was off, I'm making that difference into my targeted mash pH and targeting 5.36 in the software/spreadsheet.

This is my first Porter.

Your swift responses would be so appreciated before I start this brew this morning.

 

[billl]

If you are happy with everything except the ph, just add a bit of acid.

The sheets are just an estimate based on the water profile you put in and some average malt stats. Your water profile may change slightly from week to week and your malt may change as well. Don't worry though. Those changes are probably less than the taste thresholds.

 

[Jiffster]

If you are happy with everything except the ph, just add a bit of acid.

The sheets are just an estimate based on the water profile you put in and some average malt stats. Your water profile may change slightly from week to week and your malt may change as well. Don't worry though. Those changes are probably less than the taste thresholds.

I should have mentioned I'm using RO water. Adding acids would lower my pH, correct?

What if I find, during the mash, I need to raise my pH, say .05-.1?

 

[ajdelange]

The best way to handle this situation is to add small amounts of acid to the test mash until it reaches the desired pH. That tells you how much shy you were approximately. It would then really be best to make another test mash with the extra amount of acid to see if it will allow you to hit target. If it doesn't then you should be able to interpolate between the first test mash and second test mash to determine how much acid you need as for small changes pH is pretty linear with acid addition amount.

If you don't want to do that about the best you can do is use Weyermanns rule of thumb that 1% sausermalz generally causes an 0.1 drop in pH. If you are 0.19 pH too high you would then add sauermalz weighing 1.9% of rest of the grist.

Another rule of thumb approach is to assume that grist has buffering capacity of about 50 mEq/kg•pH. Figure out how many kg of malt are in your grist and multiply by 50 and then by the pH drop you need. This is the number of mEq of acid required. Each mL of 88% lactic acid contributes 11.4 mEq so divide by that to get the number of mL you need.

Example: you have 6 kg of grain and your mash pH is 0.19 too high. You need 6*50*.19 = 57 mEq of acid. This can be obtained from 57/11.4 = 5 mL lactic acid.

If you undershoot (mash pH too high) you proceed in the same way. If your mash pH is, for example, 0.1 too high you need to absorb 6*50*.1 = 30 mEq of acid. A gram of sodium bicarbonate absorbs 1000/84 = 11.9 mEq. So you would need 30/11.9 = 2.5 grams of sodium bicarbonate.

Keep in mind that not all base malts (the predominant contributor to mash buffering) have buffering capacity of 50 so that acid and base amounts computed using 50 may be off from what you really need. The 50 number is best used for calculating test mash corrections.

Note that the proton contributing power of 1 mL of lactic acid (11.4 mEq) is numerically about the same as the proton absorbing power of 1 gram of sodium bicarbonate (11.9 mEq).

 

[Jiffster]

Mash after 10 min is 5.39

View attachment ImageUploadedByHome Brew1470585322.664324.jpg

 

[Jiffster]

After 20 min is 5.36

View attachment ImageUploadedByHome Brew1470585954.808747.jpg

 

[Jiffster]

The best way to handle this situation is to add small amounts of acid to the test mash until it reaches the desired pH. That tells you how much shy you were approximately. It would then really be best to make another test mash with the extra amount of acid to see if it will allow you to hit target. If it doesn't then you should be able to interpolate between the first test mash and second test mash to determine how much acid you need as for small changes pH is pretty linear with acid addition amount.

If you don't want to do that about the best you can do is use Weyermanns rule of thumb that 1% sausermalz generally causes an 0.1 drop in pH. If you are 0.19 pH too high you would then add sauermalz weighing 1.9% of rest of the grist.

Another rule of thumb approach is to assume that grist has buffering capacity of about 50 mEq/kg•pH. Figure out how many kg of malt are in your grist and multiply by 50 and then by the pH drop you need. This is the number of mEq of acid required. Each mL of 88% lactic acid contributes 11.4 mEq so divide by that to get the number of mL you need.

Example: you have 6 kg of grain and your mash pH is 0.19 too high. You need 6*50*.19 = 57 mEq of acid. This can be obtained from 57/11.4 = 5 mL lactic acid.

If you undershoot (mash pH too high) you proceed in the same way. If your mash pH is, for example, 0.1 too high you need to absorb 6*50*.1 = 30 mEq of acid. A gram of sodium bicarbonate absorbs 1000/84 = 11.9 mEq. So you would need 30/11.9 = 2.5 grams of sodium bicarbonate.

Keep in mind that not all base malts (the predominant contributor to mash buffering) have buffering capacity of 50 so that acid and base amounts computed using 50 may be off from what you really need. The 50 number is best used for calculating test mash corrections.

Note that the proton contributing power of 1 mL of lactic acid (11.4 mEq) is numerically about the same as the proton absorbing power of 1 gram of sodium bicarbonate (11.9 mEq).

Thanks AJ. I was thick in the middle of my brew yesterday so I couldn't dig into your response like I wanted.

What was odd is that the pH of my test mash was 5.45 and the mash pH during the actual brew was 5.36.

I'm not sure what caused the difference as I was as careful with my measurements and process.

Bru'n water showed an estimated 5.31. I assumed my test mash number was correct and added Calcium Chloride, Baking Soda and Gypsum and got the pH to 5.35 and ran with it. (I was burning daylight).

I figured the .04 would get me to an actual 5.49.

Ironically, Bru'n turned out to have correct (off by just .01).

Not sure what happened.

I also failed to include the loss to my MLT in my water volume in Bru'n.

This was the additions I used minus any lactic acid in the final additions I used minus any lactic acid in the sparge.

View attachment ImageUploadedByHome Brew1470652445.628179.jpg

 

[ajdelange]

What happened here? Don't really know. All I can say is that as you do this more and more strange random discrepancies start to disappear. Your test mashes and your full mashes will begin to agree with one another. If there are differences between the software you use and your measurements they will appear as constant biases (e.g. spreadsheet consistently reads 0.15 pH low). What happens is that your techniques, recipes and measurement skills all improve and things begin to converge.

 

[Jiffster]

Makes sense.

Would these be a quick rule of thumb for addressing a mash pH issue during the mash:

If pH number is low - add Baking Soda
If pH number is high - add acid

 

[ajdelange]

If you want to make a rule of thumb out of it I'd suggest:

If mash pH is off multiply the weight of the grain (in kg) by 50 and the result by the desired pH shift. Then divide that number by 10 (or multiply the desired pH shift by 5). If the pH is high measure out that many mL of lactic acid. If it is low weigh out that many grams of sodium bicarbonate. Add half the measured/weighted material to the mash. Stir in very thoroughly, wait a bit and check pH. If target pH has not been reached add the remainder of the corrective material with regard to how far you still have to go. For example, if your correction was half or less of what you wanted add the entire remainder of the acid or bicarb. If you are within a hair's breadth of what you wanted don't add any of the remainder.

 

[Jiffster]

Do I have it right?

13 pounds of grain = 5.9 kg
* 50 = 295 * .15 (desired pH shift)
= 44.25

44.25/10 = 4.43

If pH is high - 4.43 mL of lactic acid
If pH is low - 4.43 grams sodium bicarbonate.

Start with half.

 

[ajdelange]

Yes.

Thinking about it further I guess we could use this to plan a brew as well. The scheme wouid be:

1. Multiply the number of liters of mash water by the water's alkalinity in mEq/L (ppm as CCO3/50) by the number of liters of water and then by 0.9.
2. Mix all the grains in the same proportion as are to be used in the mash so that you have 1 pound.
3. Mash with warm DI water. After 20 min cool and measure the pH of a sample.
4. Subtract the desired mash pH from the measured mash pH.
5. Multiply by the total kg of grains and add to the result from Step 1.
6 Divide by 10 and add that many mL lactic acid to the mash water.

 

[Jiffster]

This is for a test mash?

Is step #1 correct? Seems like there's an additional water multiplication step.

In step #2, why are we targeting 1# instead of a percentage?

In step #3 we use "warm" DI water instead of a specific mash temp?

 

[ajdelange]

This is for a test mash?

This is for any mash. Clearly you would want to do it for the full mash to get an idea as to how much acid you would need for the actual brew. You would then scale this down to test mash size and perform the test mash.

Is step #1 correct? Seems like there's an additional water multiplication step.

There is. In using 50 to correct a mash already made we are assuming that the water's alkalinity has been completely or mostly neutralized. In planning we cannot assume that unless we know it to be true. If the water's alkalinity is 0 (because it has been acidified to mash pH (which is a very good way to proceed in most cases) or if it is RO water to which no alkali has been added then skip this step. The answer would be 0.

In step #2, why are we targeting 1# instead of a percentage?

We aren't. We want a total of 1# in which the proportions (percentages) are the same as in the full mash.

In step #3 we use "warm" DI water instead of a specific mash temp?

"Warm" here means whatever temperature you intend to use for dough in.

If you don't understand completely why and how this works then don't attempt it without checking it against a spread sheet (in which case you might as well just use the spreadsheet).

I just noticed that we are not in the Brewing Science forum where the why's and wherefore's of mash pH control are discussed in detail. I probably should not have posted this here.

 

[Jiffster]

Perhaps the moderators could move the post?

 

[Jiffster]

Regarding step #2, if we have 5 different grains totaling 13 pounds, what would the math look like to scale to a 1# test batch?