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vignoles76

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I recently made wine from frozen must from Peter Brehm, two pails which makes about 5 gal after the first racking. Before pitching the yeast I let the must warm up to room temperature, measured acid: 4.65 g/l, ph: 3.46 and brix:24.6. I decided to bring the acid up to 6 g/l by adding 266g of tartaric acid. I didn't remeasure before starting fermentation. After I pressed the wine I remeasured it, acid: 5.4g/l, ph: 4.7!! Can anyone explain what may happened here? I was concerned with the ph going too low after I added acid but the opposite happened? I have never measured ph so high? I calibrate my ph meter before using every time. It measures my calibration solutions perfectly, so I don't think the measurement is incorrect. 1. Can anyone explained what may have happened? 2. What can/should I do now?
 

ceeaton

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Since you just pressed it, I'd wait a few days. When you check again, make sure you degass the sample and let it settle a bit. I've seen that before right after I've pressed, not sure if there is something that is pressed out of the skins that gives a false reading. It is one of the reasons I ordered a 3.01 pH solution to double check after I calibrated my meter (and probably didn't have to order it, but it gives some peace of mind).
 

Johnd

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I recently made wine from frozen must from Peter Brehm, two pails which makes about 5 gal after the first racking. Before pitching the yeast I let the must warm up to room temperature, measured acid: 4.65 g/l, ph: 3.46 and brix:24.6. I decided to bring the acid up to 6 g/l by adding 266g of tartaric acid. I didn't remeasure before starting fermentation. After I pressed the wine I remeasured it, acid: 5.4g/l, ph: 4.7!! Can anyone explain what may happened here? I was concerned with the ph going too low after I added acid but the opposite happened? I have never measured ph so high? I calibrate my ph meter before using every time. It measures my calibration solutions perfectly, so I don't think the measurement is incorrect. 1. Can anyone explained what may have happened? 2. What can/should I do now?
Once fermentation has started, and CO2 is present in the must, it whacks out your pH meter readings. Take a small amount and strain out the solids, put it in a small container, warm to 75F, shake repeatedly and release CO2, and measure again. Your pH shouldn’t have gone up to 4.7 during fermentation, I’ve never seen or heard of a jump that large.
 

vignoles76

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Since you just pressed it, I'd wait a few days. When you check again, make sure you degass the sample and let it settle a bit. I've seen that before right after I've pressed, not sure if there is something that is pressed out of the skins that gives a false reading. It is one of the reasons I ordered a 3.01 pH solution to double check after I calibrated my meter (and probably didn't have to order it, but it gives some peace of mind).
 

vignoles76

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Once fermentation has started, and CO2 is present in the must, it whacks out your pH meter readings. Take a small amount and strain out the solids, put it in a small container, warm to 75F, shake repeatedly and release CO2, and measure again. Your pH shouldn’t have gone up to 4.7 during fermentation, I’ve never seen or heard of a jump that large.
 

stickman

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I decided to bring the acid up to 6 g/l by adding 266g of tartaric acid.
Did you really add 266g tartaric acid? I calculate about 33g needed to get up to 6g/l from 4.65g/l. I assume the decimal is in the wrong place and you really mean 26.6g.

I have experienced the pH increase before, usually due to high potassium in the skins that gets extracted later during fermentation, but as the others have said, I've never seen a jump that high. What type of grape must did you get? With frozen must there may be acid at the bottom of the pail that can be left behind if you're not careful when transferring to a fermenter. Double check the pH meter.
 

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