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Old 03-05-2013, 02:03 AM   #1
uright
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Default Post fermentation beer ph and manipulation.

Had two beers recently finish a bit high in terms of ph. 4.64 and 4.71. I'd like to get them down to ~4.3. I plan to dose 16 oz worth of beer with one drop of lactic acid till I reach my desired ph, then scale that amount up to a corny's worth. Will this work?

It seems that something must have happened during fermentation that kept the yeast from dropping the ph any lower. I used wlp090, and pitched at 62 then let rise to 68 over 3 days. I've read that 090 can be finicky when outside it's temperature range. I'm thinking this may be the cause, as my ph's throughout the rest of the day were pretty good.

IPA
20 min mash: 5.51 @ 61f
pre boil: 5.55 @ 62
post boil: 5.35 @ 68

APA
20 min mash: 5.45 @ 63
pre boil: 5.5 @ 71
post boil: 5.34 @78

Thought/suggestions much appreciated

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Old 03-05-2013, 11:19 AM   #2
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You can try lactic and phosphoric acid and see what it does to the taste. report back what you find. I'm curious of this works for you.

Kai

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Old 03-05-2013, 12:19 PM   #3
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No reason that shouldn't work. I know Gordon Strong tweaks the pH of his finished beer but I have never done it myself for pH though I have added lactic acid to wit beer for flavor and that, of course, could be a problem for you if you use lactic. But as Kai mentioned phosphoric would do the job as well without the flavor effects.

The obvious question is as to whether you think the beer suffers in flavor from being at too high a pH. What you are seeing is high for ales that's for sure but 4.6 would not get my attention is a lager.

Obviously if your theory that the yeast didn't act normally is correct the implications go beyond the pH of the finished beer.

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Old 03-05-2013, 03:57 PM   #4
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Thanks for the input guys.

I've been scouring the web for info on how to handle finished beer ph and I'm having a hard time finding any concrete evidence. Both beers are still dry hopping but I will be tasting/testing samples with and without acid if need be. I'm really hoping that they drop down a bit.

Both beers had ~80 attenuation and I'm not noticing any off flavors. The beers do taste a little bland (not sure if that's just in my head from what I've read about high finished ph)

I'm now considering waiting until the beer is kegged to do some side by side testing with the acid additions instead of dosing the entire batch.

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Old 03-08-2013, 06:06 AM   #5
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Transferred my beer into kegs today and decided to take some samples and play around with some lactic acid additions.

First thing I noticed is that both beers have risen in ph after a 3 day dry hop. I calibrate my meter every time I use it so I'm sure the readings are accurate. My pale ale has risen from 4.64 to 4.73 and the IPA went from 4.71 to 4.8. Strange how both have risen 9 points.

I took a 100ml sample of the APA and added .05ml of lactic acid. The ph went from 4.73 to 4.11. Sampled both and noticed that the higher ph beer tasted more flabby/watery and had less bitterness up front and more of a lingering resiny bitterness when the sample was swallowed. As soon as the 4.11 sample hit my mouth it felt as though it was activating my taste buds. The bitterness was much more up front and clean. I detected more hop and malt flavor mid palate. I did pickup a tartness that was present throughout that almost had a briny quality. The slight tartness dominated the aftertaste.

I back blended the 4.11 sample with the original sample until I reached ph of 4.3. This sample was perfect. The clean bitterness upfront and malt/hop flavor midpalate were present without the tartness noticed in the 4.11 sample. The aftertaste was clean and the bitterness faded quickly.

On the IPA I took a 100ml sample and added .02ml lactic acid. This dropped me from 4.8 to 4.4. Tasting the samples yielded similar results to the comparison between the 4.73 and 4.3 samples of the APA.

I'm new to manipulating the PH of beer and I have a few questions for you. Have you noticed personally or come across any information that indicates that dry hopping can increase the PH of beer? How should I go about dropping the ph of both beers to 4.3 now that they are kegged?

Thanks

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Old 03-08-2013, 08:23 PM   #6
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0.05 ml lactic took 100 ml from 4.73 to 4.11. That's 0.81 ml per liter and 1.0 pH drop.

if you have 17 l in the keg and want to drop the pH to 4.3 you need about 0.81 * 17 * (4.73 - 4.3) = 5.9 ml

that feels like a lot. How well did you measure the 0.05 ml? 88% lactic is very viscous and doesn't easily come out of a pipette. You'll need to wash it out.

4.3 is also getting close to the pKa of lactic and the above equation assumes that you are far away from the pKa, so I would actually add 2 ml lactic to the beer, mix and see where the pH is after that.

Kai

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Old 03-08-2013, 09:00 PM   #7
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I used a 1 ml medicine syringe that is graduated in .02 increments. It's a freeby from cvs but it's all I had.

I came up with 5.63 ml per 5G which I do agree seems like a lot. Maybe beer is a strong buffer. Comparitivley, I know that 1 ml lactic will take 6g of RO water from 6.8 to 3.9. Learned that the hard way haha.

I'll start with the 2ml addition as you said then slowly add more until I creep up on 4.3. Better than to overshoot it. I'll report back with some info.

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Old 03-10-2013, 12:18 AM   #8
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I measured a commercial Leffe Blond at 4.3. One of my pales was 4.4. I found a few drops of 10% phosphoric acid dropped it to 4.35 which was optimum. It became brighter and crisper. Too much and the acid bite starts to obscure the flavor.

I found the following online by Gordon Strong

Quote:
I think the desired target range is 4.1 to 4.5, with the tradeoff being between flavor and stability. The higher the pH, the better the flavor. The lower the pH, the better the (microbial) stability.
http://www.homebrewersassociation.or...p?topic=4875.0

He went on to say 4.6 and up is bland.
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Old 03-10-2013, 05:08 PM   #9
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Nice! Thanks for the link.

I added lactic to my kegged beers yesterday. Took 4.5 ml and 5 ml to get the batches down into the area of 4.3. They do taste much better and I am not picking up any acid flavor. On to a few competitions where I can get some feedback

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Old 03-12-2013, 03:08 AM   #10
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Timely thread. I have a Munich Dunkel that came out terrible -- flat and salty is the best description. I was at a loss to understand why, and just found that the beer pH is 4.60. So I'll add a couple mL lactic acid to bring it down and report back.

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