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Old 09-01-2011, 07:46 PM   #231
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AJ, how many minutes have you seen it take for a mash pH to stabilize?


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Old 09-01-2011, 09:54 PM   #232
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Hard question to answer as pH changes continuously throughout the mashing process. The only time one really has to wait, in my experience, is when sauermalz is used. The pH can be alarmingly low at a first measurement but then drifts upward at a pretty good rate. After 10 minutes it will have increased dramatically. After 15 it should be close enough to it's "final" value that you could consider that an appropriate time to determine whether you have hit your target or not. Beyond 20 min it shouldn't change much.

If CaCO3 is used I'd expect equally long, or longer stabilization times but then I never use CaCO3 so I haven't much experience with that.


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Old 09-01-2011, 11:26 PM   #233
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I'm surprised to hear that about sauermalz. I would have expected pH to be a bit high at first, and then drift downwards.

And why does CaCO3 take a long time? Is it just the poor solubility?

I just moved, so I have yet to brew a batch where I intentionally adjust pH. I have a gallon of Five Star 75% phosphoric acid, and also a small container of calcium hydroxide (for raising pH) that I bought in a Tamil grocery store, of all places. While looking for a specific ingredient for a beer I was planning, no less. No idea what they use it for (the owner took another little container and just showed me that he gets a bit on his finger and puts it on his tongue!), but it's clearly food-grade.

One thing I'm wondering though is that, even though the CaOH is a powder, the ingredients list says it contains both calcium hydroxide AND water. Is there a typical hydrate or something, or am I going to have to perform a titration to figure out what I'm working with?
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Old 09-02-2011, 01:09 AM   #234
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I'm guessing that the lactic acid is quickly "washed" off the surface of the malt thus acidifying the liquor but takes time to penetrate into the grist where it reacts with the buffers in the malt.

Yes, calcium carbonate reacts slowly unless the pH is very low. IOW, if you put it in a beaker and pour strong mineral acid over it it will fizz giving off carbon dioxide. If you put it in water and bubble CO2 through the water it will take seemingly forever to dissolve.

Ca(OH)2 is used in western food preparation to offset acidity especially in the making if pickles.

Don't think slaked lime (calcium hydroxide) has water of hydration but if it is exposed to humid air it will, as will most substances, adsorb some water. It's probably not enough that it needs to be accounted for except in the most precise work.
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Old 10-04-2011, 07:38 PM   #235
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Quote:
Originally Posted by ajdelange View Post
A way around the lag question is to make a test mash - i.e. scale everything down to about a pound of grist and check the pH. If it doesn't come in right adjust the acid and try again. You will then know what to do for the main mash.
When doing this test is it appropriate to scale the mash water quantity down as well or is it irrelevant? Also, should it be mashed at the actual mash temp for the desired recipe?
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Old 10-04-2011, 07:53 PM   #236
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Yes (it's relevant though mash pH is not strongly dependent on amount of water) and yes, test mash should be doughed in at the strike temperature you plan to use though the sample of liquid on which the pH is measured should be cooled to room temperature.
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Old 10-05-2011, 02:20 PM   #237
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Quote:
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Yes (it's relevant though mash pH is not strongly dependent on amount of water) and yes, test mash should be doughed in at the strike temperature you plan to use though the sample of liquid on which the pH is measured should be cooled to room temperature.
What if you re using an ice bath to cool the sample and wait too long i.e. it cools to 40 - 50 degrees? Will the pH measurement still be accurate?
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Old 10-05-2011, 04:36 PM   #238
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No, the pH will continue increase as the temperature decreases.


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