pH / acid calculations

[J. Wesley]

What is the formula for the addition of tartaric acid and resultant drop in pH? A grams/ gallon = -0.1 pH, A = ?

 

[jgmann67]

1 g/L (0.13 ounce/gallon) of wine to reduce the pH by 0.1 unit.

 

[stickman]

Prefermentation pH adjustment is less of an issue, but post fermentation adjustment can be a pain. The thing you have to keep in mind is that the resulting pH is not always predictable. Any adjustment is best conducted at a small scale first to determine the result. If adjusting with tartaric acid, also remember that tartrates dropping out over time will cause the TA to drop, and the pH may shift depending on what the pH was prior to the tartrates dropping out. It is generally accepted that the pH is stable around 3.6, higher than 3.6 means that the pH will increase as the tartrates fall out, and a pH lower than 3.6 means the pH will decrease during tartrate precipitation. TA is what you taste as tart or sour, and pH is normally not something you taste, so it's a balance between target pH and TA, you really have to taste along the way giving enough time for the changes to happen. I have made post fermentation acid adjustments in increments very slowly during bulk storage that have worked well.

 

[jgmann67]

Prefermentation pH adjustment is less of an issue, but post fermentation adjustment can be a pain. The thing you have to keep in mind is that the resulting pH is not always predictable. Any adjustment is best conducted at a small scale first to determine the result. If adjusting with tartaric acid, also remember that tartrates dropping out over time will cause the TA to drop, and the pH may shift depending on what the pH was prior to the tartrates dropping out. It is generally accepted that the pH is stable around 3.6, higher than 3.6 means that the pH will increase as the tartrates fall out, and a pH lower than 3.6 means the pH will decrease during tartrate precipitation. TA is what you taste as tart or sour, and pH is normally not something you taste, so it's a balance between target pH and TA, you really have to taste along the way giving enough time for the changes to happen. I have made post fermentation acid adjustments in increments very slowly during bulk storage that have worked well.

That’s where I am now. Doing some adjustments to my pH post fermentation in bulk. Going to take it very slow, see what pH is optimal For my OVZ.

First need a good reading.

 

[Tim3]

1 g/L (0.13 ounce/gallon) of wine to reduce the pH by 0.1 unit.

You’re generally right in your equation, except that it technically reduces the TA by .1, and unfortunately PH and TA don’t have a linear relationship. It’s more of an exponential relationship.

 

[jgmann67]

You’re generally right in your equation, except that it technically reduces the TA by .1, and unfortunately PH and TA don’t have a linear relationship. It’s more of an exponential relationship.

I found that. I read a number of posts that indicate we should go slow when adding tartaric acid.... calculate how much you need, then start with a fractional amount of that. Measure, add more if necessary... like pretty much everything in winemaking, gotta take your time.

 

[Tim3]

I found that. I read a number of posts that indicate we should go slow when adding tartaric acid.... calculate how much you need, then start with a fractional amount of that. Measure, add more if necessary... like pretty much everything in winemaking, gotta take your time.

Agreed! Definitely add in stages. Also I've found that while the relationship is exponential there is quite a bit of variability. Below is what I've found. Though the good news is that once I've found the PH and TA it usually moves along the same curve. But like anything in this hobby there are always surprises!

 

[Tim3]

I actually put together a model to help track these relationships among others throughout the whole process. As long as you have a good hydrometer and PH meter for your initial inputs I've found it works very well!

 

[cmason1957]

Doesn't trying to apply a formula to the relationship between ta and ph neglect that every must is different based on the buffering capability of that individual must?

 

[Tim3]

Doesn't trying to apply a formula to the relationship between ta and ph neglect that every must is different based on the buffering capability of that individual must?

I agree every must is different, and in a perfect world lab tests would need to confirm your PH & TA readings before and after primary, and after MLF to really know what you're working with. But what I'm saying is that generally once you find your initial PH and TA, they tend to move in accordance with each other along the same curve. So if you have an initial PH of 3.5 and TA of 5.5 (and didn't acidulate), you'd likely end up at 3.77 PH and TA of 3.8 after MLF. But if you started with PH of 3.5 and TA of 6.5, you'd likely end up at 3.77 PH and TA of 5. That said you're right that the buffering capability of each must is different and the relationship is not perfect. But if a home winemaker is trying to create a game plan without lab tests, using that rule of thumb seems to be better than nothing!

 

[cmason1957]

I suppose you are correct, I can't argue in the least. But then I measure ph, get it to the level I feel is appropriate (around 3.2 for whites, around 3.6 for reds) and yes around is the right word for me. Don't try to hit some perfect number and ta, well taste matters to me much more than the number.

 

[Tim3]

I think every European winemaker would agree with you. And it's hard to argue with that.

 

[Paulietivo]

1 g/L (0.13 ounce/gallon) of wine to reduce the pH by 0.1 unit.

How are you guys measuring the TA by gram?
How many grams would one teaspoon be vs one tablespoon of TA crystals dissolved in distilled water?
Is there a general rule of thumb you all use when adding to a 6 gallon carboy post fermentation? How much is a little to start the adjustments?

 

[sour_grapes]

How are you guys measuring the TA by gram?
How many grams would one teaspoon be vs one tablespoon of TA crystals dissolved in distilled water?
Is there a general rule of thumb you all use when adding to a 6 gallon carboy post fermentation? How much is a little to start the adjustments?

Paulie, break the bank and get yourself one of these! https://www.amazon.com/Kitchen-Digi...keywords=kitchen+scale&qid=1615156946&sr=8-45

 

[Paulietivo]

Paulie, break the bank and get yourself one of these! https://www.amazon.com/Kitchen-Digi...keywords=kitchen+scale&qid=1615156946&sr=8-45

I have a kitchen scale but it never occurred to me to use it for TA crystals.
Even so how much does everyone start with when making adjustments post fermentation?

 

[Rice_Guy]

I have a kitchen scale but it never occurred to me to use it for TA crystals.
Even so how much does everyone start with when making adjustments post fermentation?

Post fermentation is usually to adjust taste. As a first step do a bench trial to see if adding acid improves the taste, wine judges have a glass and can mix in a few grains to a pinch. OK if you are in the right direction do a dilution as one gram with 49 grams of the wine and repeat looking for an ideal addition level using a five cc syringe (AKA kids meds) and several glasses with 49 or 99 grams. This is a bench trial
Pre fermentation is the normal place to do major acid changes. Post is looking at flavor changes. I have never changed post, my pre target is pH 3.1 to 3.5 and for me the normal is add sugar to balance the acid added pre ferment.

 

[Paulietivo]

Post fermentation is usually to adjust taste. As a first step do a bench trial to see if adding acid improves the taste, wine judges have a glass and can mix in a few grains to a pinch. OK if you are in the right direction do a dilution as one gram with 49 grams of the wine and repeat looking for an ideal addition level using a five cc syringe (AKA kids meds) and several glasses with 49 or 99 grams. This is a bench trial
Pre fermentation is the normal place to do major acid changes. Post is looking at flavor changes. I have never changed post, my pre target is pH 3.1 to 3.5 and for me the normal is add sugar to balance the acid added pre ferment.

Post fermentation is usually to adjust taste. As a first step do a bench trial to see if adding acid improves the taste, wine judges have a glass and can mix in a few grains to a pinch. OK if you are in the right direction do a dilution as one gram with 49 grams of the wine and repeat looking for an ideal addition level using a five cc syringe (AKA kids meds) and several glasses with 49 or 99 grams. This is a bench trial
Pre fermentation is the normal place to do major acid changes. Post is looking at flavor changes. I have never changed post, my pre target is pH 3.1 to 3.5 and for me the normal is add sugar to balance the acid added pre ferment.

What are you putting the 5 cc syringe? Is this the one gram of ta?
I dont measure TA in the wine but might start now.

 

[Rice_Guy]

* one gram of acid is too much for running a bench trial to fine tune acid, if I want to know the answer for flavor I create a dilution (ex one gram acid in fourth nine grams of wine) and accurately measure diluted acid into a glass of wine with the syringe. When judging wine we typically add two or four of those little crystals to get the effect in a glass. FYI my home balance is 0.01 gram and work is 0.001 gram so possibly I could weigh, but the lazy way is to create a dilution and measure with a syringe.
* there is a “normal range” of acid flavor vs sweet flavors in the US which is called balanced,,, ie maintains sales in grocery sales., ,,,, the figure quoted below is an example of how to compare wines. ,,,, if you have a pH meter TA is easy to measure, again measuring with a syringe

What are you putting the 5 cc syringe? Is this the one gram of ta?
I dont measure TA in the wine but might start now.

View attachment 72205
by the numbers your Cab has a high TA 1.02%, low pH 3.05, normal gravity 0.995; the two samples I put in for reference (California & Florida commercial wines) have a TA in the "normal" range.
opinion: (if I look at this as a grocery store beverage) for that high a TA the numbers would suggest that it should be sweetened to be in the orange band, however it isn't a very tannic flavor so the balance is good, transparent..clean, good flavor/ no off flavors (VA) so technically it is a well made wine. A guess is that you sourced a northern Cab for reference two juice buckets in the club were:

Cabernet Sauvignon, Chile 2020​

3.83​

1.085​

​

0.49%​

Cabernet Sauvignon, California 2019​

3.28​

1.090​

​

0.44%​

I suggested members try to get the TA to 0.65% if they were competing in state fair next year, you are balanced so ignore the "rules".
,,,,, RiceGuy