Final beer pH?

[izakdv]

For those of you who measure final beer pH, I'm curious to find out what you get on average? Especially if you start with RO (or distilled) and build a desired profile using salts.

The back story to this question is that I started to adjust my brewing water about a year ago, with good results (no more astringency/tannin aftertaste) and better efficiency, but I seem to get a very sour (low pH, but clean) end result. I bought a pH meter a few months back and my last three batches had a room-temp, post ferment (uncarbonated) pH of:
- 3.6 (belgian wit: WY-3538-PC Leuven Pale Ale),
- 3.8 (Stout: WLP004 Irish stout)
- 3.7 (Belgian dubbel: WY-3522 Ardennes).

With the last two batches I added Bicarbonate of Soda during the boil to go from a boil pH of 5.1 to 5.3 (room temp).

I suspect my very soft brewing water just has a low buffering capacity, which allows the yeast to bring the pH down from ~5.3 to ~3.7, but I would like to hear from people with more knowledge on this subject if this is plausible, and whether I am going in the right direction by adding Bicarbonate of Soda during the boil to adjust the pH.

Would you also suggest I adjust the boil pH up to like 5.6 with my next batch to see where that brings the final beer pH?

Here is my water details as in Bru'n Water:
Calcium (Ca) 10.0
Magnesium (Mg) 2.0
Sodium (Na) 11.0
Potassium (K) 3.0
Iron (Fe) 0.0
Bicarbonate (HCO3)26.0
Carbonate (CO3) 0.0
Sulfate (SO4) 18.0
Chloride (Cl) 12.0
Nitrate (NO3) 3.1
Nitrite (NO2) 0.0
Fluoride (F) 0.0
Reported Total Alkalinity (as CaCO3) (mg/L or ppm) 22.0
Reported or Measured Water pH 7.5
Estimated Bicarbonate Concentration (ppm) 26.8
Total Hardness, as CaCO3, (ppm) 33
Permanent Hardness, as CaCO3, (ppm) 12
Temporary Hardness, as CaCO3, (ppm) 21
Alkalinity (ppm as CaCO3) 21
RA Effective Hardness, (ppm as CaCO3) 29
Residual Alkalinity (RA), (ppm as CaCO3) 13

 

[ajdelange]

Most beers finish up at pH between 4.2 - 4.8 with the ales being lower and lagers higher though there is lots of overlap. Some ales get close to 4 and some sour beers will dip below 4. The fact that you are consistently below 4 is very suspicious and, if the beers taste sour, suggest infection as none of them, except the wit, should taste sour and that should taste sour because of partial fermentation with lactobacillus or because lactic acid was added to it. Buffering capacity of RO water is very low but the buffering capacity of wort isn't. Nevertheless beer pH is set mostly by the yeast who will adjust the pH to whatever value gives them a competitive edge. Thus beer pH is largely independent of wort pH. Obviously if you add alkali to wort the yeast will have to expend more metabolic effort in secreting acid than they would otherwise. It is usual to adjust wort pH into the 5.0 - 5.2 region if it is adjusted at all and this usually involves the addition of acids or salts to the kettle. It should never be necessary to adjust it up (well, I suppose one should never say 'never' in brewing).

I note that you report pH's to single decimal digits. This suggests that you may be using a pH meter with precision of 0.1 and as such meters are usually the very inexpensive ones readings from them are suspect. So tell us what sort of meter you have. Check https://www.homebrewtalk.com/f128/ph-meter-calibration-302256/ for more on pH meters in brewing.

 

[izakdv]

Thanks AJ, after reading the other thread, I realize that I made at least two mistakes here:
- Buying a $50 pH meter (HMDPHM80)
- Only doing the two point calibration once after I bought it, before each brew day I would just calibrate with the pH 4 buffer. Thinking about that now, I realize measurement based on this will probably not be accurate. I'll definitely do a better job of this with future brews. In any case, I think I see a Hach PocketPro+ in my near future...

I will note though that I noticed the "low pH" in my beers before I started measuring it.

Here is why I doubt that bacterial action is to blame:
- The sourness has no lactic or acetic character
- I always make a starter and base the pitch rate on mrmalty's calculator
- Fermentation always starts around 8 hours after pitching
- The beers usually only stay in primary for one week (sometimes even less - the Wit mentioned previously was in primary for 4 days) before I keg them and they carb up at ~38 F in the fridge.
- I am confident in my sanitation practices (I use PBW and StarSan according to directions)

The wit does have a low OG (1.035) and no crystal malt, so maybe the dryness of the final beer can somehow add to the perception of "sour"?

I also want to note that in terms of perception, both the Stout and the Dubbel that was adjusted up (during boil with Bicarb or Soda) tastes better in terms of sourness, and overall (I think the Na brings positive flavor to the water profile), though they still seem towards the lower-end of the pH range of similar examples I've had.

 

[izakdv]

After thinking about this for a while I decided to try and calibrate my pH meter properly, and test samples of the same beer again.

So I calibrated the meter to the 4 buffer, then rinsed with distilled and lightly blotted, switched to the 7 buffer and it read 7.5! I calibrated to the 7 buffer and rinsed & blotted again, then switch back to the 4 buffer...it read 3.4!

Ok, so the meter is a piece of crap.

I concede that I am not going to get accurate results from it, but at least I can get comparitive results by measuring commercial beer and my homebrew with the same calibration.

So I calibrated to the 4 buffer again (for what it's worth) and measured the following:
- Shake's chocolate porter, 3.8
- Homebrew dubbel, 3.7
- Homebrew chocolate stout, 3.7
- Homebrew wit, 3.6

This correlates with my taste perception of the beers, and it seems that the Homebrew pH is not that far off target after all.

I'll get a proper pH meter before my next brew and report back.

Thanks AJ for pointing out that the meter is probably bad

 

[izakdv]

Update: I got my Hach PocketPro+ in the mail today, and since this has been bothering me I decided to re-test the four samples.

First I did a two point calibration with the pH 7 buffer that came with the Hach, and with the pH 4 buffer I had. I used the pH 7 buffer first, but when I got to the pH 4 buffer it read ~4.5...interesting. I decided to continue with the calibration to see where the beers end up, even though I am starting to think the pH 4 buffer is suspect.

The commercial porter again tested at pH 3.81 and the homebrew stout at pH 3.70. Since this correlated more or less with my other readings I decided to re-calibrate, but just using the new pH 7 buffer that came with the Hach.

After calibration, the results were:
- Commercial porter: 4.31 @ 23.3 C
- Home brew stout: 4.20 @ 23.0 C
- Home brew Dubbel: 4.17 @ 22.9 C
- Home brew Wit: 4.12 @ 23.6 C

I will not call this definitive until I get a fresh pH 4 buffer to calibrate with, but at this point it looks like my old pH 4 buffer was partially to blame.

Live and learn.

EDIT: typo with dubbel pH, not 3.17 but 4.17

 

[ajdelange]

EDIT: typo with dubbel pH, not 3.17 but 4.17

Thought I was losing my marbles there for a minute.

 

[sandyeggoxj]

Here is something to look at. Once you get your meter dialed in you can contribute too!

https://www.homebrewtalk.com/f163/post-your-final-beer-ph-469197/