Help with PH during active fermentation

[colariu]

Hi i am new to this forum and new to wine making and i need your help. I am making some red wine (24 gallons of Merlot/Cab). and I have noticed that my PH keeps dropping during the active fermentation ( 4th day after inoculation). I started with the grapes and the PH was v high at 4. I cold soaked the grapes for 5 days and adjusted the ph to 3.43 with adding tartaric acid. I Inoculated the yeast (Renaissance) added go-ferm and i have been punching the cap 2 times a day. The must temp started at 19C and now is at 25 C. Also my SG was 1.095. Last night i measured the PH and noticed it was at 3.28 (down from the previous day at 3.3 and also down from 3.43- value of must before fermentation) Also last night my SG was 1.055 and added 16 g of Fermaid K ( did not have another 8g) I plan on performing MLF once fermentation is complete however if the trend continues i might end up at or below the required PH 3.2. I thought the ph is supposed to go up during the primary fermentation and not down. Does this seem right to you? Should i add potassium bicarbonate now, during the active fermentation to get the ph up to around 3.4? Will the PH increase by itself? I was planning to get the final ph of the wine after mlf to 3.6. Thank you!

 

[Johnd]

Hi i am new to this forum and new to wine making and i need your help. I am making some red wine (24 gallons of Merlot/Cab). and I have noticed that my PH keeps dropping during the active fermentation ( 4th day after inoculation). I started with the grapes and the PH was v high at 4. I cold soaked the grapes for 5 days and adjusted the ph to 3.43 with adding tartaric acid. I Inoculated the yeast (Renaissance) added go-ferm and i have been punching the cap 2 times a day. The must temp started at 19C and now is at 25 C. Also my SG was 1.095. Last night i measured the PH and noticed it was at 3.28 (down from the previous day at 3.3 and also down from 3.43- value of must before fermentation) Also last night my SG was 1.055 and added 16 g of Fermaid K ( did not have another 8g) I plan on performing MLF once fermentation is complete however if the trend continues i might end up at or below the required PH 3.2. I thought the ph is supposed to go up during the primary fermentation and not down. Does this seem right to you? Should i add potassium bicarbonate now, during the active fermentation to get the ph up to around 3.4? Will the PH increase by itself? I was planning to get the final ph of the wine after mlf to 3.6. Thank you!

Your pH is being affected by CO2 in the wine. If you want an accurate reading during fermentation, you should warm and place a sample in a blender for 30 seconds, strain to get clear wine, then measure pH.

 

[colariu]

I will recheck it tonight by following this method. ( i did use a strainer but did not blend it). If the ph is outside the 3.2 to 3.4 should i make any adjustments now as it still fermenting or let it complete the fermentation and adjust the PH prior to MLF?

 

[Johnd]

I will recheck it tonight by following this method. ( i did use a strainer but did not blend it). If the ph is outside the 3.2 to 3.4 should i make any adjustments now as it still fermenting or let it complete the fermentation and adjust the PH prior to MLF?

Leave it alone during AF. Make your adjustments before pitching yeast, fine tune after the wine is clear and free of CO2.

 

[colariu]

Thank you !! On a different note i plan on pressing on Friday in order to avoid high tannins and have a more approachable wine. I am assuming the FG will not get down to 1.00 ( fermentation will continue in a demijohn). Any issues with pressing early?

 

[Rice_Guy]

* wine is very forgiving, yes you can press and rack to glass at a high gravity. Some whites and meads are done in a sealed container. It is a technique used to retain fruity aroma.

I would say the pH is always lower and TA is always higher after fermentation.
My standard method for carbonated beverages is microwave 25 ml . . .

It is normal for pH to drop and TA increase as the yeast are actively producing CO2 . The numbers wouldn’t look bad at racking off a primary.
At the point where it is bottled it seems that a pH might be 0.2 units above the starting must, haven’t looked at TA enough to guess a trend but logic would suggest TA should drop.

CO2 dissolved in water creates carbonic acid, a bitter flavor note, decrease in pH and increase in TA. A less buffered system (salt form of acids) will have more dramatic swings. Earlier this month ran a seltzer water with a 1.000 gravity which was pH 3.5 fresh and 7.2 after the CO2 was removed, TA jumped from .3% to a trace (one drop). A lot of sodas will drop TA by 0.1% by removing the CO2.

The next time you see this, you could degass 45 seconds in a microwave/ 50 ml, cool and rerun to check if this was the effect observed.

 

[salcoco]

part of your PH variance is the production of carbonic acid during fermentation which is CO2 related.

 

[colariu]

so i am under the understanding that PH fluctuates during fermentation due to CO2 and that the PH reading get skewed as well. Since i started the fermentation at 3.43 i am assuming that once fermentation is complete i will be at at 3.43 maybe higher.

 

[cmason1957]

so i am under the understanding that PH fluctuates during fermentation due to CO2 and that the PH reading get skewed as well. Since i started the fermentation at 3.43 i am assuming that once fermentation is complete i will be at at 3.43 maybe higher.

That is a reasonable assumption. During fermentation your ph reading will be lower than it really is.

 

[colariu]

thanks for all the support

 

[stickman]

There are a couple of things to consider.

The adjustment to 3.43 after a cold soak, probably means that you got a more true adjustment compared to adjusting right after crushing. Often when adjusting soon after crushing, only the juice gets adjusted, and there is still potassium left in the skins that will be extracted during fermentation pushing the pH back up to some extent.

The initial pH of the fermentation also affects the change expected. The increase in alcohol content that occurs during fermentation causes potassium bitartrate to drop out of solution, if the pH is below a 3.6 when this happens the pH will drop further, if above 3.6 the pH will increase. A more conservative adjustment to 3.6 pH puts the must in a more stable position that resists pH change during the precipitation of potassium bitartrate.

There are other issues that affect the final pH, but the above are fairly common. Some things go without saying, make sure your pH meter is calibrated, and take readings on room temperature samples.

 

[colariu]

Starting with day 2 of the cold soak i was performing readings and adjustment which took some getting used to especially since i added tartaric acid and nothing happened to the PH. Since i started the fermentation at 3.43 would the PH post fermentation would the ph stabilize at a lower or higher number ? like i said i did a few readings and i am at 3.28 however i did not blend the sample for 30 seconds. (appears it is CO2 related and the true PH should be higher then 3.28). I was under the impression that in order to end up with a final pH of 3.6 in the wine i need to adjust the must at 3.4 especially since i am doing MLF.

 

[stickman]

You are getting good advice from others above. I realize this is the beginners forum and probably shouldn't have complicated things. I was just pointing out that pH adjustment is affected by several factors and isn't always totally predictable. You may or may not end up at a 3.6 pH, you'll have to wait and see.

 

[dbuchan]

I’m a newbie too, but strikes me the more you measure the more fluctuation you will see. I measured mine at the start and at the finish and had only two readings. I also suspect you are finding the wine is disappearing, have a word with your wife and ask her to stop sampling seriously though how often should we be measuring ph and sg whilst avoiding introducing oxygen?