Author Topic: pH measurements...  (Read 715 times)

Offline Village Taphouse

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pH measurements...
« on: October 06, 2015, 02:16:06 PM »
Gang:  Here's the setting... I mash in a 10-gallon cylindrical Gott/Rubbermaid cooler.  I add lactic acid to my mash to neutralize the 138ppm of bicarb I have in my source water.  I add it with a dropper and the amount usually corresponds to the SRM of the beer.  I have a small metal bowl (like you would see at a restaurant with ketchup in it next to your fries) and I freeze it in a bowl of water so I can cool my mash sample quickly.  I have a very reliable (and nice-to-use) Omega pH meter that has been a dream to work with (thanks Claudius Budde!).  So I have everything in the cooler, stir, take the temp, wait a minute or two and then grab a sample, put it in the frozen bowl, wait until it's around 70° and check the pH.  Question:  Is there data that suggests that X amount of time should go by before a good pH measurement can be taken?  I am making my Munich Dunkel this morning (I work at home, hooray) and all of that Carafa is in there and I just wonder how accurate the reading is based on the amount of time everything has been mixed together.  Thoughts?

Offline mabrungard

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Re: pH measurements...
« Reply #1 on: October 06, 2015, 02:24:15 PM »
I monitor pH at several points during a mash and can report that pH for some mashes does shift appreciably. Some don't. I had an initial reading at around the 10 minute mark that was something like 0.2 units off. I figured I'd see what it did, so I didn't perform any correction. That pH slowly crept to the predicted pH by the end of the mash. I'm not really sure what was going on there, but something was effecting the buffering in the mash. I know everything was well mixed since I use a RIMS. Its a curiousity!
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evil_morty

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Re: pH measurements...
« Reply #2 on: October 06, 2015, 02:31:09 PM »
I'm not sure of the right amount of time to wait but I have seen my pH appear to move slightly up during the first 10 minutes of the mash.  last brew I took a reading early that I was guessing was around 5.0-5.1.  took one 5 or so minutes later that seemed closer to 5.2-5.3.  could be my ability to see color or strip variability.  you are in a perfect place to check this out Ken!  you have the tools.

Offline Village Taphouse

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Re: pH measurements...
« Reply #3 on: October 06, 2015, 02:45:18 PM »
I have heard people (much smarter than I, btw) say that an accurate pH cannot be measured immediately because it takes some amount of time for everything to come together.  Someone also posted about how there can be different pH readings in different parts of the mash (something about stratification, etc) which sounds concerning although I'm not concerned about that specifically.  I envision something like adding cold maple syrup to an ice-cold glass of water... things are not dissolving and mixing together right away... they are separated which might throw off your reading.  I check the pH of the batch sparge (and the water I sparge with before it's added to the MT) and also the kettle pH so I feel pretty comfortable all the way around.

evil_morty

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Re: pH measurements...
« Reply #4 on: October 06, 2015, 02:49:21 PM »
I have heard people (much smarter than I, btw) say that an accurate pH cannot be measured immediately because it takes some amount of time for everything to come together.  Someone also posted about how there can be different pH readings in different parts of the mash (something about stratification, etc) which sounds concerning although I'm not concerned about that specifically.  I envision something like adding cold maple syrup to an ice-cold glass of water... things are not dissolving and mixing together right away... they are separated which might throw off your reading.  I check the pH of the batch sparge (and the water I sparge with before it's added to the MT) and also the kettle pH so I feel pretty comfortable all the way around.

what was said about the stratification?  was the higher pH at the top or the bottom of the mash?

Offline BrodyR

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Re: pH measurements...
« Reply #5 on: October 06, 2015, 02:52:54 PM »
10 minutes is what I do, adjust if need be, then take another one around the 25m mark. I used to do an initial reading at 5m and experienced it move when I remeasured ~15m.

I work from home too (usually) as a financial planner, need to try to slip in a full brew day one of these days haha.

Offline Village Taphouse

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Re: pH measurements...
« Reply #6 on: October 06, 2015, 02:55:49 PM »
10 minutes is what I do, adjust if need be, then take another one around the 25m mark. I used to do an initial reading at 5m and experienced it move when I remeasured ~15m.

I work from home too (usually) as a financial planner, need to try to slip in a full brew day one of these days haha.
It can be a great way to brew.... no one else in the house, etc.  I worked all day Sunday (until 3:30am Monday morning) so I figure I deserve a Tuesday brewday!  :P

Offline Wort-H.O.G.

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Re: pH measurements...
« Reply #7 on: October 06, 2015, 03:05:08 PM »
i mostly stick to about 10 minutes for a reading. i'm gently stirring the mash for about 6-7 minutes locking in my desired mash temp, then getting reading. As Martin said, there have been some differences from early reading to final reading for some-perhaps more so when specialty grain % are higher.
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Offline Village Taphouse

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Re: pH measurements...
« Reply #8 on: October 06, 2015, 03:15:44 PM »
i mostly stick to about 10 minutes for a reading. i'm gently stirring the mash for about 6-7 minutes locking in my desired mash temp, then getting reading. As Martin said, there have been some differences from early reading to final reading for some-perhaps more so when specialty grain % are higher.
Yes, I would agree that specialty grains, especially darker grains would cause things to be delayed a little bit where a lighter grist would be easier to measure earlier in the process.  That's a guess but it seems consistent with my experience.  This dunkel may be one of the darker beers I have made which is what made me wonder about this topic.  Cheers Beerheads.

Offline dilluh98

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Re: pH measurements...
« Reply #9 on: October 06, 2015, 03:31:38 PM »
I usually take one reading at 10 min and then another at the end of the mash (usually 60 min). Most often my reading at 60 min is 0.05 to 0.15 lower than the one at 10 min. Typically, if I hit the number I set out to in the 10 min reading I just go with it.

Offline BrodyR

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Re: pH measurements...
« Reply #10 on: October 06, 2015, 03:46:23 PM »
10 minutes is what I do, adjust if need be, then take another one around the 25m mark. I used to do an initial reading at 5m and experienced it move when I remeasured ~15m.

I work from home too (usually) as a financial planner, need to try to slip in a full brew day one of these days haha.
It can be a great way to brew.... no one else in the house, etc.  I worked all day Sunday (until 3:30am Monday morning) so I figure I deserve a Tuesday brewday!  :P

Nice, enjoy - I may do that next week!

Offline leejoreilly

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Re: pH measurements...
« Reply #11 on: October 07, 2015, 01:04:44 PM »
I've been using BrunWater the past few years, and I've found that my pH is always spot on, so I don't have to worry about making any adjustments to the mash. I do still take occasional pH readings, just to satisfy my curiosity (and it's geeky-cool to use the pH meter), and I always wait until at least 15-20 minutes into the mash. But if I knew that I might need to make an adjustment, I might take the measurement closer to the 10 minute mark, so whatever addition I made had some time to "work".

Offline HoosierBrew

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Re: pH measurements...
« Reply #12 on: October 07, 2015, 01:10:07 PM »
I've been using BrunWater the past few years, and I've found that my pH is always spot on, so I don't have to worry about making any adjustments to the mash. I do still take occasional pH readings, just to satisfy my curiosity (and it's geeky-cool to use the pH meter), and I always wait until at least 15-20 minutes into the mash. But if I knew that I might need to make an adjustment, I might take the measurement closer to the 10 minute mark, so whatever addition I made had some time to "work".

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Re: pH measurements...
« Reply #13 on: October 07, 2015, 01:19:41 PM »
You should always be checking and locking in pH outside of any enzymatic activity present. With that said I check my pH after 10 minutes, but I do recirculate the whole time of the mash. I want to make sure I have reached a "homogeneous" mixture. Single infusion mashes will vary very little though the entirety of the mash. Step mashes however.......

Offline neddles

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Re: pH measurements...
« Reply #14 on: October 07, 2015, 01:29:32 PM »
You should always be checking and locking in pH outside of any enzymatic activity present. With that said I check my pH after 10 minutes, but I do recirculate the whole time of the mash. I want to make sure I have reached a "homogeneous" mixture. Single infusion mashes will vary very little though the entirety of the mash. Step mashes however.......
Why is that? My pH taken 15 min. into the mash rarely differs much at all from what I get pre-boil in the kettle (theoretically after enzymatic activity)