pH decrease during fermentation

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J.Miller

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Hello,

I'm asking what could be the causes and what can I do to fix my next batch?

My wee heavy finished fermentation at pH = 3.87. After the mash and sparge the pH was at 5.28. I added pickling lime to adjust the pH to 5.72 to start the boil, and got a pH = 5.52 after the 60 minute boil. Pitched a shaken not stirred starter of harvested Wyeast 1728, and after fermentation for 7 days at 55° and then 8 days at gradually up to 67° with apparent attenuation of about 88%, the pH was at 3.87. The wee heavy is ok but too acid-tasting for my preference. I can raise the pH a little with pickling lime in my keg, but haven't done it yet.
I have experienced similar after-fermentation below 4 pH values with amber ale using harvested Wyeast 1007 shaken not stirred starters, and decided to increase the pH before the boil in my wee heavy, but still got a low pH value after fermentation.

I did a search here to find answers, but couldn't find a post with a fermentation finishing with a too low pH. I just registered here after lurking for years, so that I could ask for your advice.

Thanks much!
Jeff
 
What a great first post! Welcome to HBT!

pH will continually decline due to chemical changes during mash and boil, and then during fermentation especially due to biological processes by the yeast. This is all normal, although 3.87 seems kind of low for a finished beer, which normally will finish in the low 4's. You might want to add a little more of that pickling lime if your finished beer is tasting too tart. This might be due to the particular yeast strains. I know 1007 and 1728 are low flocculating strains so the yeast remains active for a little longer and so this might produce a bit more acid than other strains. Most people probably don't mind this and accept it as part of the character of these particular yeasts, but if it bothers you, I do love the pickling lime for little adjustments like this.

Cheers.
 
3.87 seems kind of low for a finished beer, which normally will finish in the low 4's.

My wee heavy finished fermentation at pH = 3.87....still got a low pH value after fermentation.

That's not a low pH for British beer, it's bang in the middle of the 3.7-4.1 range eg recommended by Murphys, one of the main lab service providers to British commercial brewers.

So either it's not acidity that you're tasting, or your pH meter is wrongly calibrated. Or eg you're adding too much carbonation after fermentation, one of the problems with kegging British styles is that overcarbonation can wreck the fragile balance of the beer by introducing too much carbonic acid.
 
So on average the pH will move as follows...a 5.2-5.6 early mash pH range will drop 0.2 points by end of mash, then drop 0.3 points by end of boil and then 0.8 by end of fermentation. Except for sour beers, that should put finished beer in a 4.0-4.6 range, with pale beers recommended to be in 4.0 -4.3 range, lagers around 4.5. So it seems you were 5.28 at end of mash, meaning you were most likely around 5.48-5.5 during early mash when mash pH is normally taken...which would be perfect for a dark beer. Not sure why you pushed the pH back up to start the boil though, but ok running with that, a 5.72 ph should finish around 5.42 end of boil, so your 5.52 is close enough. So then if it normally would drop 0.8 points give or take in fermentation...so should be around 4.72, so definitely weird that you are at 3.87. What are you using for a pH meter? Is it calibrated? Or if you are using strips, they are not very accurate.
 
I'm very much with Northern Brewer with this, but I'm also British.

A pH reading of less than 4.0 is what I expect and usually measure when using British yeasts to brew British style beers.

Might it be something other than acidity? Coca Cola is close to ten times more acidic than a beer at pH 3.87.
 
Hmmm

There might be something else at play here. 88% attenuation with that yeast is really high. Also you shouldn’t have seen that low of a pH with a starting fermentation pH that high and such a cold fermentation. In my experience the colder/slower the fermentation the less pH drop, especially with British yeasts. A lot of them seem to produce a lot of acid even at moderately warm temps (68). 7 days at 55 would have kept acid production to a minimum IMHO.

It’s not rare to see pH drop below 4 during fermentation but it will almost always creep back up at the end with a normal Sacch ferment.
 
Hmmm

There might be something else at play here. 88% attenuation with that yeast is really high. Also you shouldn’t have seen that low of a pH with a starting fermentation pH that high and such a cold fermentation. In my experience the colder/slower the fermentation the less pH drop, especially with British yeasts. A lot of them seem to produce a lot of acid even at moderately warm temps (68). 7 days at 55 would have kept acid production to a minimum IMHO.

It’s not rare to see pH drop below 4 during fermentation but it will almost always creep back up at the end with a normal Sacch ferment.

Not sure there's anything else at play with mine. First one brewed on August 12, mash pH 5.52, OG 1042 and kegged after 7 days at 1010.

R0010787.JPG


Second was brewed on Sept 29 and also kegged after 7 days. Mash pH 5.56 and after the boil was 5.27. OG was 1041 and at racking to keg was 1011.

R0010789.JPG


The above measurements were taken today, October 9th. The grists for both were quite similar but not identical. Both fermented with the same yeast, a British strain used by a large regional brewery that closed in 1998. The earlier brew peaked at 73F the later at 72F.

I am British and brew British beers with British ingredients fermented with British yeasts (not White Labs or Wyeast) at fermentation temperatures commonly used in British breweries made using British water profiles (Ca >100ppm<=200ppm with no mandatory upper limit for chloride or sulfate.

Yeast is pitched at around 65F and temperature is allowed to rise by the yeast's activity, which usually peaks after 2 days, then slowly declines and allowed to cool to cellar temperature in readiness to keg or cask. I read that pH does rise towards the end of fermentation, but not having measured pH until the beer is out of the FV, I haven't found pH to rise after kegging.
 
Not sure there's anything else at play with mine. First one brewed on August 12, mash pH 5.52, OG 1042 and kegged after 7 days at 1010.

View attachment 745013

Second was brewed on Sept 29 and also kegged after 7 days. Mash pH 5.56 and after the boil was 5.27. OG was 1041 and at racking to keg was 1011.

View attachment 745015

The above measurements were taken today, October 9th. The grists for both were quite similar but not identical. Both fermented with the same yeast, a British strain used by a large regional brewery that closed in 1998. The earlier brew peaked at 73F the later at 72F.

I am British and brew British beers with British ingredients fermented with British yeasts (not White Labs or Wyeast) at fermentation temperatures commonly used in British breweries made using British water profiles (Ca >100ppm<=200ppm with no mandatory upper limit for chloride or sulfate.

Yeast is pitched at around 65F and temperature is allowed to rise by the yeast's activity, which usually peaks after 2 days, then slowly declines and allowed to cool to cellar temperature in readiness to keg or cask. I read that pH does rise towards the end of fermentation, but not having measured pH until the beer is out of the FV, I haven't found pH to rise after kegging.

Those are fully degassed samples?

If you’re just letting fermentation free rise with no control then yes those ph values aren’t that far off depending on pitch rate and a few other variables.

The 88% attenuation at 55 degrees with a yeast that hovers around 70% usually is what was more abnormal to me.

I’ve measured pH at every gravity check during fermentation for hundreds of beers over the last few years. I’ve only seen one Sacch ferment get below 4.0 ever and that was with wlp073, a weird “French ale” yeast strain. All were temp controlled with glycol. I would consider a degassed final beer pH below 4.1 to be rather acidic.

I’ve seen a very healthy pitch of 1318 fermented at 68 controlled get below 4.1 but then bounce back to over 4.2 at the tail end of ferment. I also use a Kolsch strain that will get close to 4.1 but again always bump back up to the high 4.2s to 4.3.

I use a few Brett strains that will take beers to 3.8-3.9 and the acidity is very noticeable in my opinion.
 
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According to the brewing science literature (cf Google's misinformation), ales have a pH range between about 3.7-4.2. Lagers can be above >4.2. The lazy 'average for beer' often propagated on google (by clueless plagiarists) ignores some important detail, especially between ales and lagers.
 
I did my best to decarbonate the beers in the short time available to me at that time. However the samples were left untouched since then and have this morning taken further readings. Moving the first sample to a more convenient place, some of the contents were spilled, but enough remained for a rading and the second sample wasn't moved.

R0010790.JPG


R0010791.JPG


So yes, the pH readings are higher, but not significantly so.

I remember well a post some time back when revealing finished beer to AJ, who while not dismissing the possibility of such low readings considered them to be unusual. Yet, it was near enough bang in the middle of those advised by the major British brewing consultancy in Uk for over a century. It remined me of my first visit to the first Chinese Restaurant in my home town and for a long time thinking I knew what Chinese food was. Of course it was cooked to appeal to British customers with local ingredients, totally different to Chinese food in Hong Kong where the restaurant owners originated.
 
If you’re just letting fermentation free rise with no control then yes those ph values aren’t that far off depending on pitch rate and a few other variables.

Well if we're talking about typical British styles, then free rise is a typical part of the fermentation profile. Don't try to impose foreign profiles on a style. And I could equally well say that to the OP :

fermentation for 7 days at 55° and then 8 days at gradually up to 67° with apparent attenuation of about 88%

This thing of Scottish beers being fermented cold is just a myth. Typically they might be pitched at say 15°C/59°F, maybe a couple of degrees less for high-gravity worts that would generate more heat, but they would soon be free-rising to 20-21°C/68-70°F. See eg :

https://barclayperkins.blogspot.com/2016/09/was-scottish-ale-fermented-like-lager.html
I’ve measured pH at every gravity check during fermentation for hundreds of beers over the last few years. I’ve only seen one Sacch ferment get below 4.0 ever

But I assume you're mostly fermenting with heavy dry hops, which increase pH by around 0.025-0.03pH/(g/l). So a 20g/l dry hop (~14oz/5 US gal) on its own will increase pH by 0.5-0.6 pH. The OP didn't give his recipe, but I assume he's not doing that for a Scottish style.

I see Sapwood are typically coming in at around 4.5-4.6 :

https://scottjanish.com/a-look-at-ph-in-hoppy-beers/
 
Well if we're talking about typical British styles, then free rise is a typical part of the fermentation profile. Don't try to impose foreign profiles on a style. And I could equally well say that to the OP :

But I assume you're mostly fermenting with heavy dry hops, which increase pH by around 0.025-0.03pH/(g/l). So a 20g/l dry hop (~14oz/5 US gal) on its own will increase pH by 0.5-0.6 pH. The OP didn't give his recipe, but I assume he's not doing that for a Scottish style.

Just cause it’s typical does it mean it’s correct? A final beer pH of 3.8 caused by a uncontrolled fermentation that’s allowed to free rise to whatever it wants with a yeast that produces a lactic profile doesn’t sound like a beer I’d be interested in drinking. Some English yeasts are nice and fruity at higher temps, in a pleasant way. Others are Lactic bombs that produce piles of higher alcohols regardless of their starting gravity.

1318 at high temps is pleasant
002/006/1968 uncontrolled is disgusting

Yes I do often make highly dry hopped beers but I’m taking gravity and pH readings every day or every other day of fermentation. Yes dry hops do increase pH but pH naturally increases on its own at the end of fermentation regardless. Never seen one yeast or one fermentation where it didn’t happen.
 
According to the brewing science literature (cf Google's misinformation), ales have a pH range between about 3.7-4.2. Lagers can be above >4.2. The lazy 'average for beer' often propagated on google (by clueless plagiarists) ignores some important detail, especially between ales and lagers.

from every batch I’ve ever made both at home and now commercially I’d say these numbers are a bit low. By about .2

A lot depends on yeast strain, beer, ferm temps, etc. But even with KO pH adjusted to 5.0ish and very little buffer in the wort (no alkalinity) I’ve rarely ever seen numbers that low. Kolsch yeast I use will get sub 4.1 but always climb back up. I’ve seen 34/70 get below 4.2 once but again always climb back up. Never seen any other lager strain get that low.
 
Allowing a fermentation to 'free rise' from a relatively low pitching temperature (say, 17℃) is not as uncontrolled as attempting to play ping-pong between enforced cooling and heating phases hopelessly aiming to maintain a set temperature, ironically. As long as the upper temperature limit for a given strain isn't passed (which is rarely the case, unless there's a heatwave going on outside) during the initial stages of fermentation (some say the first 24 hours) it really isn't a problem. I've never heard of any British yeast strains being 'lactic bombs'. If you don't enjoy English ales, don't offer advice on brewing them, I say.
 
Allowing a fermentation to 'free rise' from a relatively low pitching temperature (say, 17℃) is not as uncontrolled as attempting to play ping-pong between enforced cooling and heating phases hopelessly aiming to maintain a set temperature, ironically. As long as the upper temperature limit for a given strain isn't passed (which is rarely the case, unless there's a heatwave going on outside) during the initial stages of fermentation (some say the first 24 hours) it really isn't a problem. I've never heard of any British yeast strains being 'lactic bombs'. If you don't enjoy English ales, don't offer advice on brewing them, I say.

Who said I don’t like English ales? I don’t like English ales with a clear lactic profile which is often caused by certain yeasts fermenting at high temps.

In a 68* environment even pitched at 62* plenty of English yeasts will go way north of 72 if uncontrolled. Some are nice and fruity at those temps. Others are horribly lactic.
 
Who said I don’t like English ales? I don’t like English ales with a clear lactic profile which is often caused by certain yeasts fermenting at high temps.

In a 68* environment even pitched at 62* plenty of English yeasts will go way north of 72 if uncontrolled. Some are nice and fruity at those temps. Others are horribly lactic.

Sounds like it might be something to do with your process, to be honest. It's not unusual for home brewers to deviate from expectations. We all introduce biases to procedures as individuals. Some deviate more than others.
 
I don't like lactic either, nor know any British publican who might conceive to serve any traditional British Ale that had the remotest of lactic twangs. I'm sorry, but there is something wrong with your process or the yeasts that you find with such traits.

In my last picture is the vial that held the yeast used in those beers, behind the sample being measured. It's a British yeast from a British supplier, not a purported British yeast from a third party. An empty vial to the right of that came from a third party, but its pedigree was assured and confirmed by its performance. Some White Labs and Wyeasts are probably as described, but some don't compare when used in place of the actual yeast for the period of concern.

Even the supposed style in this thread is no more a style than is ESB, which is just the name of a beer brewed by Fullers. Well, Ron Pattinson says so, and his opinion is more authentic than BJCP's for me.
 
Sounds like it might be something to do with your process, to be honest. It's not unusual for home brewers to deviate from expectations. We all introduce biases to procedures as individuals. Some deviate more than others.

Zero wrong with my process. As I said I’ve never seen pH values that low in any beer of mine during any fermentation, and especially at the end of fermentation. 400 + batches in stainless steel in the last 5 years or so all with temp control. I’ve experienced it in plenty of other beers. In my experience of measuring plenty of commercial beers as well as mine once pH gets close to 3.9 it’s pretty noticeable to me. Maybe others not so much.
 
Zero wrong with my process. As I said I’ve never seen pH values that low in any beer of mine during any fermentation, and especially at the end of fermentation. 400 + batches in stainless steel in the last 5 years or so all with temp control. I’ve experienced it in plenty of other beers. In my experience of measuring plenty of commercial beers as well as mine once pH gets close to 3.9 it’s pretty noticeable to me. Maybe others not so much.
Yep, it definitely sounds like it might be something to do with your process. I didn't say you were necessarily doing anything wrong, but I think the probability of an individual home brewer refuting the brewing science literature is vanishingly small. It seems you're only considering your own results, as some kind of standard? Doesn't that invite bias into your thought processes to promote a kind of belief system? I guess that kind of slippery slope is partly what makes it easier for some to deny science, too.
 
Yep, it definitely sounds like it might be something to do with your process. I didn't say you were necessarily doing anything wrong, but I think the probability of an individual home brewer refuting the brewing science literature is vanishingly small. It seems you're only considering your own results, as some kind of standard? Doesn't that invite bias into your thought processes to promote a kind of belief system? I guess that kind of slippery slope is partly what makes it easier for some to deny science, too.

Do some more research on final beer pH.

I’ve done plenty with my beer, measured plenty of commercial beers, listens to tons of professionals talk about their beers and pH.
 
Hello,

I'm asking what could be the causes and what can I do to fix my next batch?

My wee heavy finished fermentation at pH = 3.87. After the mash and sparge the pH was at 5.28. I added pickling lime to adjust the pH to 5.72 to start the boil, and got a pH = 5.52 after the 60 minute boil. Pitched a shaken not stirred starter of harvested Wyeast 1728, and after fermentation for 7 days at 55° and then 8 days at gradually up to 67° with apparent attenuation of about 88%, the pH was at 3.87. The wee heavy is ok but too acid-tasting for my preference. I can raise the pH a little with pickling lime in my keg, but haven't done it yet.
I have experienced similar after-fermentation below 4 pH values with amber ale using harvested Wyeast 1007 shaken not stirred starters, and decided to increase the pH before the boil in my wee heavy, but still got a low pH value after fermentation.

I did a search here to find answers, but couldn't find a post with a fermentation finishing with a too low pH. I just registered here after lurking for years, so that I could ask for your advice.

Thanks much!
Jeff

Hi Jeff, as seen in the posted pictures, your final pH finding is not unusual for ales. Here you can read a paper to The Institute of Brewing that includes this particular subject. The following is part of the opening.

Fermentation reduces the pH by a further unit yielding ales with pH values of about 3·8-4·2, or lagers of pH 4·2–4·8. Literature evidence does not suggest any obvious reason why ales and lagers should differ in pH.

Ales not being at the forefront of beer production during much of the 20th century in some parts of the world has resulted in a belief that what was true to lager must necessarily apply to ale. In Britain we had similar when home brewing without license began in 1963 and winemakers told brewers how it should be done. After several decades myths prevailed and even today still raise their heads above the parapet.

As you found, raising pH before fermentation will not necessarily raise final pH, but as ales should always have a final pH of the order of 4, plus or minus some, I suggest there is a reason other than final pH for your "Wee Heavy" tasting as it does.

Have you tried adding some pickling lime to your finished beer and if so, what the result might have been.
 
Wow, I am happy and inspired that I got all these replies! Thank you much. Dave, dmtaylor - what a nice compliment you made. I know, some Wisconsinites complement fellow Wisconsinites. Appreciated.

My delay in replying is due to an unexpected continuation of the past very busy couple of weeks for me and my family. I didn't mean for a delay this long.

Here is more detailed information.

72% golden promise, 6% each of flaked barley, crystal 40, special B, victory, 3 % flaked wheat, 1.3% roasted barley, 24 IBU of EKG hop at 60 minutes.

RO water with 73ppm Ca, 0ppm Mg, 8ppm Na, 45ppm SO4, 99ppm Cl mash. RO water with 147ppm Ca, 3ppm Mg, 29ppm Na, 70ppm SO4, 163ppm Cl boil kettle

Mashed with recirculation and without crystal and roast grains for 60 minutes, and adding them before the sparge with RO water. Step mashed at 134° for 10 minutes, with 5.75 pH at 3 minutes, added 0.3 ml 10% phosphoric acid, 5.69 pH at 5 minutes, added 0.5 ml phosphoric, at 10 minutes raised temperature to 150° at 13 minutes, 5.64 pH at 21 minutes, stirred mash at 28 minutes, 5.63 pH at 34 minutes, at 43 minutes raised temperature to 170° at 46 minutes, put in crystal and roast malts at 61 minutes, stirred mash at 65 minutes, pulled up basket (Anvil Foundry 6.5) at 71 minutes and sparged with 171° RO water, 5.28 pH at 87 minutes. The sparge RO water was at about 6.5 pH. Bru'n Water predicted a 5.51pH mash at this point in the brewing.

At 21 minutes into a 60 minute boil, I added pickling lime and measured a 5.72 pH at 24 minutes, then 5.52 pH at 60 minutes and end of boil.

jdauria asked what pH meter I used and if calibrated. I used an Apera PH 60, two point calibrated per it's instructions. The pH readings were made with wort cooled to 69° ±, about same as calibration liquid.

From the wyeast 1728 smack pack, I began a shaken not stirred starter per the S. cerevisiae procedure in April 2021, but did not brew with it, instead harvesting it and storing in a sanitized, tight-capped plastic soda bottle under the dme "beer" at 40° for 2 months. In June 2021, I made another shaken not stirred starter with the harvested yeast using about 75 to 100 ml of the harvested cake for brewing this wee heavy. I added the yeast before shaking. I don't know scientifically if infection was present, but the second starter appeared and smelled normal to me. At the start, the refractometer reading was 11.0 brix (1.045 ±), and at pitching the starter into the wort, it was at a 5.2 brix (1.005 ±). I took a refractometer reading because no krausen developed. The starter fermented at 72°, pitched into a 75° wort, in a soda keg with burton union on the gas post, and placed in my 55° temperature controlled freezer for fermentation.

The OG was 1.089± and FG was 1.010±. I have since checked my refractometer and hydrometer with 12 °P sugar water and distilled water, and made new correction constants, and therefore the specific gravity results are off by about 0.0003, making the apparent attenuation less than 88%. However, the mash schedule temperature of 134° was used to get a less fermentable wort and a higher finishing gravity, and some time to get multiple pH readings, but I didn't get a less fermentable wort.

cere asked if I added pickling lime to the finished beer, No, I didn't.

I have pH tested a number of commercial dark lager and ale beers and found values above 4. Thanks, Northern Brewer for your replies of Murphy's recommendations of a 3.7 to 4.1 pH range to British commercial brewers. Interesting.

I'm asking what could be the causes and what can I do to fix my next batch? I'd like a fix to the low pH prior to the fermentation stage.

I have brewed several low IBU ambers with Maris Otter base malt and harvested wyeast 1007 yeast in shaken not stirred starters, and each got less than 4 pH for the end of fermentation, and low FG values - high apparent attenuations. The acidity tatse I detect is more pronounced in these lower ABV ambers. Could it be that the 3 or 4 generations of harvesting the yeast be a cause for the high attenuations and low pH? Could using too much volume of harvested yeast be a cause? S. cerevisiae has said he uses surprisingly little yeast volume.

Thanks, and thanks to all for your replies.
Jeff
 
cire, I read the article you linked. All good information. The reported storage of lager yeast resulting in better fermentation and lower pH is an item that may cause my situation with storage of ale yeast. My wee heavy was a second use while my ambers were second and more uses.
 
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