Author Topic: Tell me about kettle and fermentation pH  (Read 2544 times)

Offline nateo

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Tell me about kettle and fermentation pH
« on: September 09, 2012, 10:26:53 AM »
I've started keeping track of my pre-boil and pre- and post-ferment wort pH, but I'm not really sure what numbers I should be aiming for. Any advice? Gordon goes over this a little bit in his book, but I'm interested in some more perspective.
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Offline Kaiser

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Re: Tell me about kettle and fermentation pH
« Reply #1 on: September 09, 2012, 12:47:11 PM »
A pre-boil pH of 5.4-5.5 is a good target. The cast out pH should be around 5.2-5.4.

As for beer pH, it will depend on the beer style. My lagers tend to be around 4.3 and ales are a bit less.

Kai

Offline mabrungard

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Re: Tell me about kettle and fermentation pH
« Reply #2 on: September 16, 2012, 01:18:07 PM »
Beer pH has a lot to do with the yeast used.  There are some yeasts that naturally reduce beer pH more than others.  I would worry more about the kettle pH values since those are more in your control.
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Offline nateo

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Re: Tell me about kettle and fermentation pH
« Reply #3 on: September 16, 2012, 01:20:02 PM »
There are some yeasts that naturally reduce beer pH more than others.

Yeah, I've noticed that with wine yeasts in meads, sours and ciders, but I've only recently begun tracking the pH for everything I make.
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Offline nateo

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Re: Tell me about kettle and fermentation pH
« Reply #4 on: September 17, 2012, 05:56:44 AM »
I brewed a blonde ale last week. Pre-boil pH was 5.5 and post-boil was 5.4. Is it normal for the pH to not fall much during a boil? If I find my pH to be high, would it be worth it to try to get it into the 5.4-5.5 range? The pre-boil pH for the beer I made for the fauxpils study was 5.7, IIRC. Do you guys have a rule-of-thumb for how much acid to start with, so I don't overshoot? I always have 10% phosphoric and sour, unhopped wort on hand.
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Offline Kaiser

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Re: Tell me about kettle and fermentation pH
« Reply #5 on: September 17, 2012, 06:47:32 AM »
Do you guys have a rule-of-thumb for how much acid to start with, so I don't overshoot?

From my titration experiments I remember that wort had a buffer capacity of about 30 mEq per kg extract and 1.0 pH. drop. For 5 gal of 12 Plato wort, this means you need about 0.6 ml lactic acid (88%) or 7 ml 10% phosphoric acid to drop the pH by 0.1 units.

When I acidify the wort I and up adding about 2 ml lactic acid, which drops pH by about 0.2 units. I can check my notes when I'm home tonight.

Kai

Offline Alewyfe

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Re: Tell me about kettle and fermentation pH
« Reply #6 on: September 17, 2012, 08:30:33 AM »
A pre-boil pH of 5.4-5.5 is a good target. The cast out pH should be around 5.2-5.4.

As for beer pH, it will depend on the beer style. My lagers tend to be around 4.3 and ales are a bit less.

Kai

??Ales a bit less??  I'm trying to "process" this pH stuff, but i would have expected that lagers would run lower than ales. Why the converse effect?.

I just did an Ordinary Ale recipe that I have done many times with no water adjustments. This last batch I inadvertently got the mash pH a little low (5.1..those pesky room temp vs mash temp numbers, grrr) It finished with a pH of 4.1 and I thought it was quite a bit different and what I would best describe as more lager like than previous batches.   Also, I've read so much stuff lately that i can't remember where I got the numbers from, but IIRC,  around 4.4 was a number sited by tasting panels as being most prefered and drinkable as a post fermentation pH. I going to start measuring all my favorite comml beers out of curiosity.
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Offline Kaiser

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Re: Tell me about kettle and fermentation pH
« Reply #7 on: September 17, 2012, 08:34:27 AM »
??Ales a bit less??  I'm trying to "process" this pH stuff, but i would have expected that lagers would run lower than ales. Why the converse effect?.

Ale fermentations tend to be stronger than lager fermentations, which leads to a larger pH drop. But this is not a hard rule, though.

Kai