How much baking soda to bring 12 pz of 4.02 pH beer to ~4.5 pH?

[Silver_Is_Money]

I just measured the pH of my finished and bottled Pils/lager at 4.02, which is rather low. How much baking soda (in grams, or fractions of grams) would I need to add to a 12 ounce bottle to raise it to 4.5 pH. I'd like to see if it tastes more mellowed at pH 4.5 than at 4.05, since to me it seems a bit tart, despite being in the bottles now for 2 months post fully achieved carbonation.

I will admit that I didn't fully decarbonate the sample before I got the 4.02 pH reading. Whatever decarbonation it got was due to my stirring the pH probe in it for a bit before taking my reading. Might the remaining carbonation be skewing my pH downward?

 

[Silver_Is_Money]

BTW, my first guess is to try adding 1/10 of a gram, mixing, and taking a new pH reading.

 

[ajdelange]

IMO that is exactly what you should do unless you have information about the buffering capacity of the beer from some other source.

 

[couchsending]

You need to decarbonate it fully.

What was the PH at the start of fermentation?

 

[Silver_Is_Money]

What was the PH at the start of fermentation?

Unknown

 

[ajdelange]

I once determined (at John Palmer's request) that 1 vol of CO2 would displace the pH of beer down by 0.1 pH. To do that I must have had a value for the buffering of beer but don't remember where I got it or what it was. Perhaps Kai measured it?

 

[Silver_Is_Money]

I once determined (at John Palmer's request) that 1 vol of CO2 would displace the pH of beer down by 0.1 pH. To do that I must have had a value for the buffering of beer but don't remember where I got it or what it was. Perhaps Kai measured it?

So due to not removing all of the carbonation my 4.02 was likely a bit of a lowball pH measurement.

 

[ajdelange]

Yes, it would depress the measurement somewhat but most of the CO2 escapes early when beer is disturbed so I wouldn't expect it to be shifted by much. Less that 0.1 anyway,

 

[couchsending]

A PH that low is rather odd for Lager yeast isn’t it? Certain ale yeasts will get that low but generally not Lager I didn’t think. PH meter is recently calibrated?

 

[Silver_Is_Money]

A PH that low is rather odd for Lager yeast isn’t it? Certain ale yeasts will get that low but generally not Lager I didn’t think. PH meter is recently calibrated?

Calibrated in 4 and 7 buffers right before taking the reading. Yeast was W-34/70.