Author Topic: mash pH increase  (Read 1068 times)

Offline brewinhard

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mash pH increase
« on: July 08, 2015, 01:47:22 PM »
I understand that the mash pH will increase over the duration of mashing.  Does anyone know approximately how much it increases by and about how long this initial increase takes in time to first occur?

Offline brewinhard

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Re: mash pH increase
« Reply #1 on: July 09, 2015, 11:10:52 PM »
No thoughts from anyone?  Just felt like bumping it up.... 8)

Offline quattlebaum

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Re: mash pH increase
« Reply #2 on: July 10, 2015, 01:12:55 AM »
Back in the day i did do a tedious 10min PH sample over a 90 min mash schedule of 100% pils with 100%RO and the PH seemed to stabilize for me at the 20min sample. over that 90min duration i hardly noticed any change in elevation in PH maybe .04 of a point. so it was irrelevant for me. I am sure there are many variables such as grist, minerals and what not but i didnt feel like splitting hairs:) currently i just take a sample at 15min mark so i have the time to adjust if needed. hope this helps.

Offline dmtaylor

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Re: mash pH increase
« Reply #3 on: July 10, 2015, 02:04:38 AM »
My chemical engineering background suggests that the pH might indeed increase slightly, and that this would happen very quickly right away, like in the first 3-5 minutes of the mash.  This would be due to reaction of calcium and magnesium with phosphates to precipitate out.  After that, based on the complexity of all the reactions going on, I could only guess that the pH would either stabilize completely, or might actually decrease from there while acidic compounds slowly leach more and more out of the malt husks.
Dave

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Offline brewinhard

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Re: mash pH increase
« Reply #4 on: July 12, 2015, 11:25:52 PM »
Thanks for the thoughts!

rabeb25

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Re: mash pH increase
« Reply #5 on: July 13, 2015, 04:39:24 PM »
My pH will raise during my mash, as I raise my step temperature. With a single infusion it is consistent, I measure at 15min in.

Offline johnnyb

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Re: mash pH increase
« Reply #6 on: July 13, 2015, 04:51:32 PM »
Just a data point from Saturday.

Initial pH of mash (5 minutes in) = 5.39

After 60 minutes = 5.39

Post boil = 5.29

Edit: All measured at 75o.


Meter was pH56 with two point calibration performed same day in fresh solutions.
 
« Last Edit: July 13, 2015, 05:27:28 PM by johnnyb »

Offline brewinhard

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Re: mash pH increase
« Reply #7 on: July 13, 2015, 06:37:10 PM »
Very interesting.  Cool data.  Thanks for sharing.

Offline johnnyb

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Re: mash pH increase
« Reply #8 on: July 13, 2015, 07:51:15 PM »
No prob.

I should have mentioned I did a single infusion, so my results were consistent with rabeb25's observations.

Offline johnnyb

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Re: mash pH increase
« Reply #9 on: July 18, 2015, 09:08:53 PM »
Another data point today:

Single infusion @ 148o

pH @ 5 minutes into mash = 5.26 measured at 75o

pH @ 60 minutes into mash = 5.26 measured at 75o

I haven't boiled as I'm souring with lactic bacteria until tomorrow.


Neither of these two recipes (this one and the earlier data point) had much crystal, and no more than 2 ounces of roasted malt in each. Both times I added the roasted during the batch sparge just for the color.

It seems like recipes with close to 100% base malt do not rise with a single infusion mash. It's possible that recipes with a lot of crystal and roast might be different.

Offline dmtaylor

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Re: mash pH increase
« Reply #10 on: July 19, 2015, 05:38:55 PM »
It seems like recipes with close to 100% base malt do not rise with a single infusion mash. It's possible that recipes with a lot of crystal and roast might be different.

I don't know why or where this is coming from.  If anything I might expect the opposite, but now I'm more inclined to think it is stable after the first 5 minutes, regardless of the contents of the grist.  More specialty malts would tend to bring the 5-minute mash pH down closer to 5.0.  Less or zero specialty malt should get you closer to 5.8-6.0 (undesirable).
Dave

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Offline johnnyb

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Re: mash pH increase
« Reply #11 on: July 19, 2015, 08:01:00 PM »
It seems like recipes with close to 100% base malt do not rise with a single infusion mash. It's possible that recipes with a lot of crystal and roast might be different.

I don't know why or where this is coming from.  If anything I might expect the opposite, but now I'm more inclined to think it is stable after the first 5 minutes, regardless of the contents of the grist.  More specialty malts would tend to bring the 5-minute mash pH down closer to 5.0.  Less or zero specialty malt should get you closer to 5.8-6.0 (undesirable).

Nope, you are correct I would expect the opposite too. Somehow I had my thinking cap on backwards.