fermentation (and other) factors that influence final beer pH

[navethechimp]

Hey guys,

Question
I'm struggling to find reliable resources to understand what gets my beers from their post-boil pH to their final pH in the glass. Anyone have their own evidence or links to some publications? I have been googling and searching the forums for some literature or good resources on this topic. Mash pH is a widely studied and documented topic, so no troubles there.

My Anecdotal Experiences
My final beer pH is consistently higher than commercial examples of the same style. I generally brew low to mid strength pale beers, both lagers and ales. My pH meter usually reads 4.5 to 4.7 pH on my finished product, with no obvious flavor defects. My water profiles are very soft, fully built up from bottled distilled--little to no hardness and with 50-150 ppm of the aesthetic ions, depending on the style. My mash pH is usually 5.3-5.4 and I get fine conversion. I don't add salts to my sparge water, but I do acidify it to make sure I hit my target boil pH. Commercial examples of the same styles generally range between 4.2 to 4.5 pH on the same meter, including everything from a world class IPA to a pale ale or a Weihenstephaner pils to a Modelo Especial. What is driving me crazy is that I can add phosphoric acid to my finished beer to get it to a similar level in a side-by-side tasting with a commercial equivalent, and the increased brightness improves the flavor of the beer--usually getting it as good or better than the commercial one I am comparing it to. Why do I have to add acid post fermentation to take it from good to great, rather than letting yeast and other upstream processes take care of it?

Possible Factors

• Increased mash, pre-boil, and/or post-boil pH (i.e. pale grain bill, less negatively charged ions from salts) -> final pH higher
• Increased amino acids (from a weak hot break) that buffer around 4.9 pH -> final pH higher
• Increased oxygenation -> final pH ?
• Yeast or bacteria strain -> effect on pH varies by strain
• Increased pitch rate -> final pH ?
• Increased fermentation temperature -> final pH ?
• Longer contact with yeast, leading to autolysis -> final pH higher
• Increased dry hop levels -> final pH higher
• Increased carbonation (and thus carbonic acid) -> final pH ?
• Increased hardness acting as a buffer for the rest of these factors -> final pH higher

FWIW, this is the most valuable thread I have been able to find, but it's mostly a reference, not really helping me understand why:
https://www.homebrewtalk.com/showthread.php?t=469197

Thanks guys!

 

[Grod1]

sorry i dont have much to add but for the sake of the name of the post these are some things that will influence final beer ph . grain recipe(specifically acid malt), adjuncts. yeast/other bacteria/ fermentation temp.

 

[Lefou]

Do you add calcium salts to the mash water?
No..wait, you do...
Yeast strains aren't all the same, some will affect your final beer pH. For reference, search out BYO articles regarding how yeast choices can affect your final pH. Great reading.

 

[kevinthestout]

Two factors might be:

1) Commercial brewers will take the beer off the yeast sooner than home brewers.
2) Commercial brewers usually achieve a much better hot break than home brewers.

During fermentation pH will drop until primary fermentation is complete. At this point the first stages of yeast autolysis will start and the pH will rise. Commercial brewers will usually drop out the settled yeast at this point.

Commercial brewing kettles often operate above atmospheric pressure and will achieve a far more violent boil than a homebrew setup. This gives a better hot break and consequently the concentration of amino acids in the fermentor is lower. Typical amino acids in wort buffer at around pH4.9 which is somewhat higher than the target pH for most beers.

The other thing I wonder is why you only add brewing salts to the mash. IMHO this is generally a bad idea because you allowing oxalates through to the kettle and possibly the final beer. I'm not sure whether it might pull other buffers (phosphates?) into the wort which would also contribute to a higher final pH.

Whatever the cause is, I would suggest that you monitor pH throughout the fermentation. If you see it fall and then rise it would point to mechanism 1. If it falls, but slows around pH4.9 before picking up again that would suggest mechanism 2. If it does neither , I could always be wrong

 

[cire]

....................

The other thing I wonder is why you only add brewing salts to the mash. IMHO this is generally a bad idea because you allowing oxalates through to the kettle and possibly the final beer. I'm not sure whether it might pull other buffers (phosphates?) into the wort which would also contribute to a higher final pH.

Whatever the cause is, I would suggest that you monitor pH throughout the fermentation. If you see it fall and then rise it would point to mechanism 1. If it falls, but slows around pH4.9 before picking up again that would suggest mechanism 2. If it does neither , I could always be wrong

Yes, will cause final ph to be high. Lagers made with modest ion levels will have a final pH near 4.5 while ales with higher ion levels and top fermenting yeasts will have final pH typically from 4.1 to 3.8. Low alkalinity and adequate calcium in the mash produces a suitable pH, but only half the calcium, will transfer into the kettle. There in this case the deionised sparge liquor will dilute it to a level able to deposit a smal portion of the materials that instread of being deposited will go into solution and transfer into the fermentor. At the least they will have a buffering effect and possibly react with the acid added to lower pH.

A too high pH in finished beer dull flavors, reduces shelf life and increases potential for infection.

 

[navethechimp]

Thank you so much for the time and thoughts, especially, kevinthestout, for signing up just to give his great response.

I will be updating the first post so that if anyone else finds this helpful then it'll all be consolidated.

sorry i dont have much to add but for the sake of the name of the post these are some things that will influence final beer ph . grain recipe(specifically acid malt), adjuncts. yeast/other bacteria/ fermentation temp.

Yeast strains aren't all the same, some will affect your final beer pH.

Grain and adjuncts are inferred in "mash and boil pH", but I will reword that to be more clear. Yeast strain is huge, and I am comparing my homebrews against commercial beers that use the same yeast, but, similarly, I'll update the thread for completeness.

Two factors might be:

1) Commercial brewers will take the beer off the yeast sooner than home brewers.
2) Commercial brewers usually achieve a much better hot break than home brewers.

During fermentation pH will drop until primary fermentation is complete. At this point the first stages of yeast autolysis will start and the pH will rise. Commercial brewers will usually drop out the settled yeast at this point.

Commercial brewing kettles often operate above atmospheric pressure and will achieve a far more violent boil than a homebrew setup. This gives a better hot break and consequently the concentration of amino acids in the fermentor is lower. Typical amino acids in wort buffer at around pH4.9 which is somewhat higher than the target pH for most beers.

Whatever the cause is, I would suggest that you monitor pH throughout the fermentation. If you see it fall and then rise it would point to mechanism 1. If it falls, but slows around pH4.9 before picking up again that would suggest mechanism 2. If it does neither , I could always be wrong

This is all news to me. I will measure throughout fermentation of my next batch, and, if you nail it with either of these two suggestions, you are my new brewing hero. I'm adding these above, as they are possible factors, even if they are not at play in my beers in question.

The other thing I wonder is why you only add brewing salts to the mash. IMHO this is generally a bad idea because you allowing oxalates through to the kettle and possibly the final beer. I'm not sure whether it might pull other buffers (phosphates?) into the wort which would also contribute to a higher final pH.

Yes, will cause final ph to be high. Lagers made with modest ion levels will have a final pH near 4.5 while ales with higher ion levels and top fermenting yeasts will have final pH typically from 4.1 to 3.8. Low alkalinity and adequate calcium in the mash produces a suitable pH, but only half the calcium, will transfer into the kettle. There in this case the deionised sparge liquor will dilute it to a level able to deposit a smal portion of the materials that instread of being deposited will go into solution and transfer into the fermentor. At the least they will have a buffering effect and possibly react with the acid added to lower pH.

I don't understand this. Parts per million is calculated based on the total amount of water used, or at least it is in the EZ Water speadsheet I use. My understanding is that, regardless of whether or not it's added during mash or sparge, the same amount of water, and thus a proportional amount of dissolved solids, are going to get retained by the grains, keeping the profile at target.

Below is the profile for one of my hoppy lagers. The "Mash + Sparge Water Profile" is my target, using 4 gallons in the mash (with salt additions) and 5.5 gallons (without salt additions). Am I thinking about this incorrectly?

(note the "Diluted Water Profile" is if I'm doing a split batch, diluting a strong wort across a handful of fermenters for experiments or something. Ignore that. :cross

If anyone has any insight into fermentation factors (temp, pitch rate, oxygenation) on pH, please share! Maybe they don't influence it like I am assuming. Haha.

 

[Silver_Is_Money]

Lager yeast generally brings a beers final pH into the 4.4 to 4.7 range, whereas ale yeast generally brings a beers final pH into the 4.1 to 4.4 range. Might this explain some of what you are seeing?

Also kettle "knock out" pH is generally about 0.3 lower than mash pH.

 

[kevinthestout]

I don't understand this. Parts per million is calculated based on the total amount of water used, or at least it is in the EZ Water speadsheet I use. My understanding is that, regardless of whether or not it's added during mash or sparge, the same amount of water, and thus a proportional amount of dissolved solids, are going to get retained by the grains, keeping the profile at target.

Below is the profile for one of my hoppy lagers. The "Mash + Sparge Water Profile" is my target, using 4 gallons in the mash (with salt additions) and 5.5 gallons (without salt additions). Am I thinking about this incorrectly?

.

So if I understand you correctly, in the above example you want a profile with 71ppm of calcium and to achieve this you're adding 165ppm to the 4 gallons of mash water.

That's not as bad as I'd assumed from your first email, but It's not quite the same as adding 71ppm calcium to your sparge and mash water. Towards the end of your sparge you'll be running demineralised water through the grain bed. You acidified your water so that you don't extract tannins at this point. For similar reasons it's preferable to have calcium in the water so that you don't extract other undesirable compounds.

It might just be splitting hairs, and I mostly mineralise the sparge water because my process means it's easy to just add the salts to the HLT.

 

[navethechimp]

So if I understand you correctly, in the above example you want a profile with 71ppm of calcium and to achieve this you're adding 165ppm to the 4 gallons of mash water.

Yep, exactly.

It might just be splitting hairs, and I mostly mineralise the sparge water because my process means it's easy to just add the salts to the HLT.

Homebrewers are often split around mineralizing their sparge water. The conditions for tannin extraction are often not met. Far from homebrewers biggest worries in my opinion. That said, I bet there's a direct correlation with homebrewers having one burner and one kettle vs. having a dedicated HLT and whether they add salts to their sparge vs. not. The math for me is annoying with one kettle. Better to increase it up front.