# pH & Finished Beer



## Mardoo (1/8/17)

Hi folks,

I've started paying attention to the finished pH of my beers, more as a learning exercise than anything else. However, I do understand that it can have a relative effect on flavour and bitterness perception. I'm interested in hearing things folks have learned by paying attention to the final pH of their beers. 

I also have a process question which I have yet to find an answer to. Should the beer be carbonated before reading post-ferment pH? It seems like the amount of dissolved carbonic acid would affect final pH, and therefore the final pH should be tested once and while the beer is at its final level of carbonation.


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## Lyrebird_Cycles (1/8/17)

Whilst laboratory practice is to degas samples*, residual CO2 has very little effect on the pH of finished beer because beer pH is very close to the apparent pKa of dissolved carbonate.

Final pH has an effect on flavour balance: when testing this (over twenty five years ago) I found a difference of 0.05 unit was perceptible and 0.1 was obvious.

If you correct the final pH (as I sometimes do for dry hopped beers where the pH can rise**) the type of acid used also makes a difference: I recently split a batch and did half with lactic and the other half with sulphuric and I strongly prefer the one with added sulphuric.

* Easily achieved by pouring the beer from one beaker to another and back again about 10 times. An ultrasonic bath also works well but the beer can gush and then you have to clean the bath.

** I believe this is likely to be due to potassium in the hops.Most plants preferentially uptake potassium


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## n87 (1/8/17)

Lyrebird_Cycles said:


> Residual CO2 has very little effecton the pH of finished beer. If you want to measure total organic acids you'll need to degas, but generally not for pH.
> 
> Final pH has an effect on flavour balance: a difference of 0.05 unit is perceptible, 0.1 is obvious. If you correct the final pH (as I sometimes do for dry hopped beers where the pH can rise*) the type of acid used also makes a difference: I recently split a batch and did half with lactic and the other half with sulphuric and I strongly prefer the one with added sulphuric.
> 
> * I believe this is likely to be due to potassium in the hops.Most plants preferentially uptake potassium



I am curious on the differences that... say 0.1 unit can make.
Do different (not infected ) beers favour different acidity?


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## rude (1/8/17)

Good post I'll be reading with interest Mardoo
I think the Brewdog recipes on some of them had a final PH reading
was around 4.6 I think without checking
With darker beers Brun suggests a higher mash PH so does it finish higher as well ?


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## Lyrebird_Cycles (1/8/17)

n87 said:


> I am curious on the differences that... say 0.1 unit can make.



When I set this up it was with a very large volume selling bog standard Australian beer... think green cans.

One brewery in the group consistently ended up with lower final pH from the use of sugar syrup as an adjunct instead of glucose syrup. The corrective action was to dose potassium carbonate in the filter room.

We set up a tasting trial of different dosing rates (and thus pHs). It was a long time ago but I remember being able to pick up the differences mentioned. Lower pHs tightened up the palate structure and made the beer seem thinner, higher pHs tended towards soapiness. Large additions of carbonate gave a burnt effect on the palate but I believe that is due to the mixing of the carbonate into the beer, not the pH as such.



n87 said:


> Do different (not infected ) beers favour different acidity?



I believe so but I don't have the data on beer to back that up.

I know it's the case with wine: of the ones I bottled last week, the whites (a pig, a sab and a fiano) all had pHs around 3.25, the red (a tempranillo / graciano blend) had a pH of 3.55. If you reversed these the red would look thin and harsh and the whites would look flabby and tired.


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## wide eyed and legless (1/8/17)

Gordon Strong's take on this taken from the American Homebrewers Association site.

I did some research and experimentation with this last summer while working on my book. 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. Above 4.5, you start to get into food safety issues (i.e., stuff can grow in it). Lowering the pH does make the beer seem thinner, and eventually starts getting tart. I only used phosphoric acid (it's an ingredient in soft drinks as a flavor enhancer).

When the pH of beer is above 4.6 or so, it does have a bland taste, sort of like underseasoned (undersalted) food. Adding phosphoric acid did improve the flavor, to a point. Like salting food, there is an optimal point and it's somewhat subjective. Going too far means you start tasting the flavor enhancer and not the enhanced flavor. The flavor impact was different based on the serving temperature as well. Measuring at room temperature and then tasting at the colder serving temperature can result in over-adjusted beer. The desired final pH is also affected by the flavor profile (beer style) of the subject beer; there isn't one magic pH where all beers taste best.

I did find that finished beer did buffer pH change quite a bit. Certainly more so than RO water. Another way of illustrating that adding acids to adjust pH is not something with an easy linear formula. You have to add and test carefully, at least until you've neutralized the buffer and start moving the pH.


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## TheWiggman (1/8/17)

Very interesting LC, glad to have your input.


Lyrebird_Cycles said:


> ... would look thin and harsh and the whites would look flabby and tired.


I'll add these adjectives to my tasting vocabulary.


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## MHB (1/8/17)

Mucking about with some Potassium Hydrogen Carbonate (Pot-BiCarb) and Cider.
The Cider was twangy and thin with a very noticeable acidity, as it was adjusted up to around 4.2pH, it totally changed, even the apple flavor came all the way to the front after being almost totally invisible in the start cider.
The difference is very pronounced.
Mark


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## Mardoo (1/8/17)

Fascinating stuff guys! Totally stoked I asked.


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## Mardoo (1/8/17)

Here's something I downloaded for free last year from the MBAA website (so I assume it's public domain), a paper by Charlie Bamforth that's an overview of pH in brewing. I had forgotten I had this and started digging around in my computer this afternoon and found it. This specific excerpt is about beer final pH, but there is a lot more to the paper that will be of interest. I'll attach it below:

*BEER *

As beer pH decreases over the typical range from 4.5 to 3.9 there is:

ï increased resistance to microbial spoilage
ï increased colloidal stability (for reasons not fully understood) ï increased foam stability (for reasons not fully understood, [42]) ï decreased flavor stability
ï (possibly) decreased palate smoothness and drinkability

Brenner et al. [7] say pH affects the quality of bitterness. Rigby [48] claims that bitterness is harsher at higher pH values. However Simpson et al. [52] found no impact of pH on the flavor threshold of isohumulone.

Simpson[50]showed that the antimicrobial activity of hop bitter compounds is much greater when they are in their uncharged forms, at low pH, pKa values for the iso-α-acids are of the order of 3.

Grigsby et al [20,21] demonstrated that the tendency of beer to oxidize is less at higher pHís. Nordlov and Winell [44] suggest that this can be explained in terms of the impact of pH on the dissociation constant for the adducts formed between staling carbonyl compounds and sulfur dioxide, but Kaneda et al. [29] invoke the role of pH in protonating the superoxide radical to form the much more damaging perhydroxyl species. The pKa for this interconversion is 4.88.

Pellaud et al 45] observe that at a given temperature the major parameter influencing the precipitation of oxalate is pH: at pH 4.5 as compared to 4.0 there is a far greater opportunity for cal- cium to precipitate oxalic acid.

Taylor [57] looked at the impact of pH on flavor by altering pH through addition of acids. At low pH (< 4) beers became more sharp, with an increased drying character in the after-taste and an increased perceived bitterness. At pHís < 3.7, there was a metallic after-palate, while especially at pH > 4.4, soapy and caustic notes were reported. Higher pHís were accompanied by comments about mouthcoating, biscuit and toasted.

Siebert [49] highlights that it is not simply a role for organic acids as a supplier of H+ that causes their sourness impact, but that structural features of these molecules also determine their flavor threshold.


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## Jrrj (2/8/17)

Great thread Mardoo! I've been meaning to raise this topic for months. For me the issue is taste - I find I just love lower-pH balanced foods and drinks.

Ever since I read Gordon Strong's thoughts on the subject in Brewing Better Beer, I've been interested. Testing my beers I've found finished pH (pre-carbonation) consistently higher than the supposed ideal levels - typically around 4.4-4.5 and never below 4.35 (using a just-calibrated Hanna Halo to test each time).

I also tested a degasses sample of S&W Pacific Ale, which is the summer beer I want to get close to. From memory (I've lost my records) it was close to pH 4.0 - so a lot lower than my attempts.

I'm hoping that nailing finished-beer pH adjustment with phosphoric (as suggested by Strong) will finally reproduce that sharpness of a cold S&W PA downed in the heat of summer.

Using 85% phosphoric acid seems to require a fair bit of precision and effort though - repeatedly diluting a solution with a 0.02ml pipette before anything can be added to a small beer sample for taste testing. Once I get around to this I'll post about the experience here.


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## Mardoo (2/8/17)

This has really got me thinking about the effects of recipe and process on final pH. Hmmmm...


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## Jrrj (2/8/17)

So I just did some testing on my current batch in the fermenter. It has fully attenuated (1.007 gravity) but the pH has only come down to 4.71, so definitely a candidate to experiment with phosphoric acid pH adjustment.

To your point about process and recipe - for this beer I didn't bother with any acid or salt additions to the hot liquor (Melbourne West tap water), and used only wheat and ale malt. Unsurprisingly the pH was high at every stage of the brewing process (mash pH was 5.7).

When I made a Belgian Witbier with similar grain bill earlier this year I adjusted the hot liquor to 6.2 pH with phosphoric acid, and added some gypsum and calcium chloride, which ended up with 5.4 mash pH and 4.35 finished beer pH.

Based on those two experiences I don't think I'll skip the acid and salts next time!


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## manticle (2/8/17)

I've never measured finished beer pH but my understanding has always been that getting mash, sparge and boil pH correct should result in expected finished beer pH.

Interesting topic, worth reading more about.


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## Jrrj (4/8/17)

Yesterday I tested another S&W Pacific Ale bottle and got pH 4.15 +- 0.02 at about 15 degrees (completely degassed). (And 1.009 FG in case anyone ever wondered).

So taking that as my benchmark, the plan is to modify samples of my current brew to a range of different pH levels (say 4.1 to 4.5 in 0.1 increments), chill then taste to see what I notice.

Obviously this is not going to be blind, or in any way scientific, but it should at least give me a subjective guess at how much I need to worry about final pH (since I consume most of my beer myself).


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## mtb (26/8/17)

This is a VERY useful thread - especially given the ongoing discussion about whether or not water chemistry is worth looking into.
Recently bit the bullet and bought a pH meter, and found that my finished beer is consistently around 4.6; no lower than 4.5, at least.

@Lyrebird_Cycles you mentioned sulfuric was preferred over lactic to reduce pH. Would I find sulfuric locally at all? Can't find much via Google.


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## rude (26/8/17)

mtb said:


> This is a VERY useful thread - especially given the ongoing discussion about whether or not water chemistry is worth looking into.
> Recently bit the bullet and bought a pH meter, and found that my finished beer is consistently around 4.6; no lower than 4.5, at least.
> 
> @Lyrebird_Cycles you mentioned sulfuric was preferred over lactic to reduce pH. Would I find sulfuric locally at all? Can't find much via Google.



What do you mean whether water chemistry is worth looking into
Mate there is no need to discuss any more
It is worth it 100% dead set cert


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## fletcher (26/8/17)

mtb said:


> This is a VERY useful thread - especially given the ongoing discussion about whether or not water chemistry is worth looking into.
> Recently bit the bullet and bought a pH meter, and found that my finished beer is consistently around 4.6; no lower than 4.5, at least.
> 
> @Lyrebird_Cycles you mentioned sulfuric was preferred over lactic to reduce pH. Would I find sulfuric locally at all? Can't find much via Google.



there's an ongoing discussion about whether or not it's worth it? i find that hard to believe. i've only been adjusting my water for about a year and have noticed remarkable improvements in my beers. perhaps you're referring to your internal discussion? if so, silence the haters and nay-sayers; it is incredible.


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## twinathon (26/8/17)

Is there any academic material that links fermentation health to final pH? I test all of my brews for final pH and aside from one imperial stout, they were all within 4.0 - 4.2 pH. The imperial stout was as high, I think something like 4.75. Perhaps relevant is the fusels that were present on the finish of the stout, which is a characteristic of a poor ferment.


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## mtb (27/8/17)

Yeah alright, point taken, it's certainly worth the effort. In any case I'm keen to get my hands on sulfuric since I definitely can taste lactic acid in higher dosages, or a different acid if anyone has another idea.


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## fletcher (27/8/17)

mtb said:


> Yeah alright, point taken, it's certainly worth the effort. In any case I'm keen to get my hands on sulfuric since I definitely can taste lactic acid in higher dosages, or a different acid if anyone has another idea.



try phosphoric acid. should be able to get it from a good brew store. I've not been able to notice it at all in all the beers I've brewed.


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## Dan Pratt (27/8/17)

subscribed.

for a brewer that has taken to water chemistry as an integral part of making great beers, final beer pH is not something I have measured buy certainly will do.

Brewdog shoe 4.4 on most beers and A look into commercial beers would be interesting.


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## fungrel (27/8/17)

mtb said:


> Yeah alright, point taken, it's certainly worth the effort. In any case I'm keen to get my hands on sulfuric since I definitely can taste lactic acid in higher dosages, or a different acid if anyone has another idea.


Grain and grape stock it, amongst others.


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## manticle (27/8/17)

@mtb - phosphoric as mentioned but how much lactic are you adding to be able to taste?


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## mtb (27/8/17)

manticle said:


> @mtb - phosphoric as mentioned but how much lactic are you adding to be able to taste?


4mL in a keg containing ~15L.


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## mtb (27/8/17)

Thanks guys - phosphoric looks the go. I'll grab some and see how it goes.


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## manticle (27/8/17)

mtb said:


> 4mL in a keg containing ~15L.


4mL at what percent lactic? Sounds like a lot to me but haven't run through calculation. Starting pH? Target pH?


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## mtb (27/8/17)

4.8 starting pH, 88% concentration, need to double-check the post lactic pH but I think it's around 4.4.


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## Mardoo (27/8/17)

That does sound like a lot.


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## mtb (27/8/17)

No more than what I hear some people add to the mash though, I guess the flavour is more prominent when adding post fermentation?


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## manticle (27/8/17)

There's all sorts of chemistry going on in a mash that resists pH changes.


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## Mardoo (27/8/17)

Also, different sensory thresholds for different people. I once shifted the pH 0.4 points with an acidulated malt addition at 4% of the grain bill. For the first three weeks after ferment I kept tasting sour flavours in the beer, but my mate couldn't taste it at all. Then the flavour faded. Once I revisited the recipe I realised that it may have been the acidulated malt I was tasting. When I took it out, no more sour flavour, but my mate had never tasted it. Not all tongues are the same.


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## Jack of all biers (27/8/17)

mtb said:


> 4mL in a keg containing ~15L.



That is a lot. Are you sure your finished beer pH is 4.4 after that addition?



mtb said:


> No more than what I hear some people add to the mash though, I guess the flavour is more prominent when adding post fermentation?



That maybe true, but adding to what size mash volume? To counteract what alkalinity? Even using Adelaide tap water, my last sparge water was at pH 7.1 and 3 ml 90% Phosphoric and took it to pH 4.76 (that last addition of 0.5ml got me again). That was 37L sparge water. I know that is like comparing apples to grapefruit, but point is, I'd be concerned adding 4 ml of 88% lactic (or any acid for that matter) to 15 L of beer. That is extreme and no wonder it left it apparently sour.

I think the whole point of the different research, all points back to ensuring that the all things are taken care off along the way of a brew. It's a whole package thing, that when you get to the point of having to add acid to the final product, then you have failed somewhere further up the chain. Ensuring quality ingredients (including water), attention to mash criteria (temp/pH/grist/water ratio etc), attention to yeast viability and vitality, attention to fermentation temps and on and on...

Point is, it is definitely worth knowing how things affect other things along the way and how to fix up mistakes as you go, but adding 4ml of lactic acid to 15 L of beer, should be causing alarm bells. The kind that say, don't do it, don't do it....


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## mtb (28/8/17)

I should correct myself - 2mL in 15L of 4.8. Resulting pH is 4.55, which is nowhere near the reduction you saw @Jack of all biers, so I'm not too sure where that's gone wrong. The bottle is labelled 88% so it's not a concentration thing. You also definitely have a point re failing further up the chain - this is my attempt to correct pH in an already finished brew. I now take pH readings throughout the mash to nip the problem in the bud.

Moving forward, I've gotten myself a 1L bottle of 85% Phosphoric. I'll run some test batches to dial in the required additions and see how I go from there.


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## Jack of all biers (28/8/17)

My example wasn't a good comparison, hence the apples and grapefruit comment. Your beer and my water would have vastly different buffering capacity, but the volume comparison was what I was highlighting, so sorry for the bad comparison.


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## Jrrj (29/8/17)

I don't think I came back with the results of my experimentation with phosphoric.

My notes from a few weeks ago - feel free to point out where I went wrong with my back of the envelope calculations!

- 11 August I took a pH sample and it measured high 4.7s. I added 2ml of a 1/800 dilution of 85% phosphoric acid to 80ml beer sample, then this tested pH 4.05. This would imply that 19lt/.08lt x 2ml = 475ml will give the same result in a whole keg. To reduce that slightly, 400ml of the dilution could be tried in the whole batch, which is the same as 0.5ml of pure 85% phosphoric acid in the batch. To avoid spoiling the batch, I propose to add 0.2ml then test pH, then 0.2ml again then test pH, then a further 0.1ml at a time if additional pH reductions are desired. Following that, I will take final gravity measure, carbonate and then serve.
- 15 August I progressively added approximately 5ml of 85% phosphoric to approximately 18 litres of uncarbed beer that had measured pH 4.7 previously (0.5ml, then 0.5ml, then 1ml, then 2ml, then 1ml, shaking the keg and letting it settle for a couple of minutes between each sample, which was taken through the liquid post from a beer gun). Post addition pH test scored 4.36. These results suggest conclusions from the previous testing had been invalid (ie the assumption that 0.5ml would move the batch from 4.7s to 4.1s. Perhaps the 1/800 sample jar was mislabelled or miscalculated and should have been 1/80 dilution? Or had otherwise changed?).​
Since my earlier posts on this thread I also went back and re-read what Gordon Strong says on the subject in Brewing Better Beer. The main conclusion I drew from that was to adjust my brewing water to pH 5.5 with phosphoric, and to include Magnesium Sulfate in my salt additions (6g Calcium Sulfate, 2g Calcium Chloride, 2g Magnesium Sulfate added to 40lt of water). I'm hopeful that this will solve my problem of high pH throughout the brewing process.


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## Lyrebird_Cycles (30/8/17)

mtb said:


> I should correct myself - 2mL in 15L of 4.8. Resulting pH is 4.55, which is nowhere near the reduction you saw @Jack of all biers, so I'm not too sure where that's gone wrong.



88% Lactic is near enough to 12M (molar) and monoprotic so you have 12 m moles H+ per ml _if fully dissociated_. The pKa is 3.86 so at beer pH it is not fully dissociated; your 2 ml should represent about 20 m moles H+.

The buffering capacity of beer is generally around 90 m moles H+ / [ pH x kg extract] or 12 mmoles H+ / [pH x litre] at around 13 oP. I would therefore expect you to move 15 litres of wort by about 0.1 pH unit with this addition.

Note: edited to correct error in density of lactic solution


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## mtb (30/8/17)

Lyrebird_Cycles said:


> 88% Lactic is near enough to 10M (molar) and monoprotic so you have 10 m moles H+ per ml _if fully dissociated_. The pKa is 3.86 so at beer pH it is not fully dissociated; your 2 ml should represent about 15 m moles H+.
> 
> The buffering capacity of beer is generally around 90 m moles H+ / [ pH x kg extract] or 12 mmoles H+ / [pH x litre] at around 13 oP. I would therefore expect you to move a little less than 0.1 pH unit with this addition.


As always your input is appreciated LC. Last night Bru'n Water and a newly acquired 1L bottle of 85% Phosphoric helped me to achieve a great mash pH and subsequent on-point pH levels. The proof will be in the final product though, I re-brewed a previous lager that ended up at 4.8 post fermentation and tasted.. "muddy". This time around I hope for a much better result.


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## Lyrebird_Cycles (30/8/17)

Jrrj said:


> - 15 August I progressively added approximately 5ml of 85% phosphoric to approximately 18 litres of uncarbed beer that had measured pH 4.7 previously (0.5ml, then 0.5ml, then 1ml, then 2ml, then 1ml, shaking the keg and letting it settle for a couple of minutes between each sample, which was taken through the liquid post from a beer gun). Post addition pH test scored 4.36.​


​
5 ml of 85% phosphoric contains about 7 g of acid, MW is about 100 so that's 70 m moles. Phosphoric is effectively monoprotic at beer pH* so that's 70 m moles H+.

Using the metric given above, that should move your beer pH by about 0.33 pH units, very close to what you report.

Did you by any chance do the 1/800 dilution by weight? If so that introduces an error of about 70%: 85% phosphoric has a density about 1.69 g/ml.

* The pKa for the second and third dissociation are each well above beer pH so they don't come into play.


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