Is this a contradiction??

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Tnuscan

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Cold Stabilization

Cold stabilization is tricky! The procedure involves placing the wine in cold storage at a temperature between 25° and 40° F (-4° and 4° C) for a minimum of three weeks and then racking it. This has the effect of precipitating the tartaric acid as potassium bitartrate salt *— the tartrate crystals you find at the bottom of a bottle of wine that you forgot and left in the fridge for too long — which decreases acidity and hence TA. However, remember that potassium contributes to a higher pH. When it precipitates during cold stabilization, it then lowers the pH. This effect actually happens at a pH of 3.65 (use 3.6 if you have a 0.1 precision pH meter) or lower because of the relative concentrations of tartrate and potassium in the wine. At a pH of 3.65 or above, cold stabilization will actually raise the pH.

First underline----Decreases acidity----- isn't this raising the pH

Second underline-----It then lowers the pH----- how can it lower the pH if it's removing the acid

Third underline-----At a pH of 3.65 or above, cold stabilization will actually raise the pH.

Seems as if removing the acids would be raising the pH @3.65 or less, yet
Last sentence states above this number.
 

Stressbaby

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Tartaric acid has TWO hydrogens to donate, that's key. It gives the first at average pH of 2.9, second around 4.3. Note that 3.65 is almost exactly in the middle of 2.9 and 4.3.

"T" is tartaric acid. Here is the chemical equation.

H2T <--> HT- <--> T--

You can plot this with pH along the X axis. The max amount of HT- is at pH of 3.6, right in the middle of 2.9 and 4.3. At 2.9 there are roughly equal amounts of H2T and HT- and at 4.3 there are roughly equal amounts of HT- and T--.

Whenever you cold stabilize, you are precipitating potassium bitartrate, or KHT. KHT removes HT- from the equation. The wine wants to maintain equilibrium.

So if the pH is above 3.6, you are completely on the right half of the equation and you can ignore the left half. Removing KHT as wine diamonds removes HT-, and to maintain equilibrium some T-- grabs a hydrogen, moves to the left and converts to HT- which raises the pH.

If your pH is below 3.6, you can ignore the right and only worry about the left half of the equation. Remove KHT and, again, you are removing HT-. In order to maintain equilibrium H2T shifts to the right, converting to HT- and H+. This is giving up a hydrogen, decreasing the pH.
 
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Stressbaby

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@Tnuscan - np - I have to write it down myself in order to keep it straight!
 

Tnuscan

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so....all chemistry and math aside....does it taste better or not?
Lol. Well....I can't say just yet, the Chambourcin came out a little more acidic than I was aiming for. The muscadine was very acidic, it smells so good it's unbelievable. I still don't understand how the muscadine got so acidic on me.

The Cynthiana/Norton turned out nice, I was shooting for a little higher pH but I'm happy. I will play with oak and tannins as they age. Going by some of the posts I figured fermentation and MLF would raise the pH more than it did.

For this to be my first wine from grapes, I really can't complain, I have gained a lot of valuable knowledge, which makes my head hurt. But the wine seems to ease the pain. ::
 
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Stressbaby

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I made Chambourcin this year. What are your numbers?
 

Tnuscan

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I made Chambourcin this year. What are your numbers?
Chambourcin pH 3.30 TA 10 g/L

Cynthiana pH 3.92 TA 6 g/L

Noiret pH 3.5 TA 5.5 g/L

Ok... I split the Cham. into 2 batches using 2 different yeasts. While I was doing it I thought I wouldn't press, instead I would take the skins from both batches of Cham. and do a second run if it turned out nice my friend would bottle it. Well....

I later (like last month) read that the skins would have a higher pH than the free run. One batch of the free run was larger than the other. One was more acidic than the other. 1st batch pH was 3.30, 2nd batch was 3.23, (smaller of the two).

The pressed wine from the skins, from the Second run had a pH of 3.6, even though it had added water and added sugar. But the character is completly different. (I won't do this again).

I have no doubt if I had pressed and added the skins pressing back to the Two batches, the pH would be close to my goal.

All of my wine and batches went through Mlf and completd with sucess, @ 10 weeks.
 
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Johnd

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Chambourcin pH 3.30 TA 10 g/L

Cynthiana pH 3.92 TA 6 g/L

Noriet pH 3.5 TA NA (waiting on new regent)

Ok... I split the Cham. into 2 batches using 2 different yeasts. While I was doing it I thought I wouldn't press, instead I would take the skins from both batches of Cham. and do a second run if it turned out nice my friend would bottle it. Well....

I later (like last month) read that the skins would have a higher pH than the free run. One batch of the free run was larger than the other. One was more acidic than the other. 1st batch pH was 3.30, 2nd batch was 3.23, (smaller of the two).

The pressed wine from the skins, from the Second run had a pH of 3.6, even though it had added water and added sugar. But the character is completly different. (I won't do this again).

I have no doubt if I had pressed and added the skins pressing back to the Two batches, the pH would be close to my goal.

All of my wine and batches went through Mlf and completd with sucess, @ 10 weeks.
Consider a little tinkering:

Pot. Bicarbonate will help the chambourcin, raining the pH and lowering the TA.

I'd work some tartaric into the cynthiana, especially with a pH close to 4. Take it easy and you may get it down a bit without increasing the TA too much.

Noriega is TBD once you get the TA.
 

Tnuscan

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Consider a little tinkering:

Pot. Bicarbonate will help the chambourcin, raining the pH and lowering the TA.

I'd work some tartaric into the cynthiana, especially with a pH close to 4. Take it easy and you may get it down a bit without increasing the TA too much.

Noriega is TBD once you get the TA.
Thanks John,

The Pot. Bicarb., and new regents, should be delivered today or tomorrow. I
put a batch through the Vadai barrel,racked, put another in a few days ago. I've been reading up on tannin and will order it in a day or so.

Following your posts have taught me, low and slow on the additions.
 

geek

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Tartaric acid has TWO hydrogens to donate, that's key. It gives the first at average pH of 2.9, second around 4.3. Note that 3.65 is almost exactly in the middle of 2.9 and 4.3.

"T" is tartaric acid. Here is the chemical equation.

H2T <--> HT- <--> T--

You can plot this with pH along the X axis. The max amount of HT- is at pH of 3.6, right in the middle of 2.9 and 4.3. At 2.9 there are roughly equal amounts of H2T and HT- and at 4.3 there are roughly equal amounts of HT- and T--.

Whenever you cold stabilize, you are precipitating potassium bitartrate, or KHT. KHT removes HT- from the equation. The wine wants to maintain equilibrium.

So if the pH is above 3.6, you are completely on the right half of the equation and you can ignore the left half. Removing KHT as wine diamonds removes HT-, and to maintain equilibrium some T-- grabs a hydrogen, moves to the left and converts to HT- which raises the pH.

If your pH is below 3.6, you can ignore the right and only worry about the left half of the equation. Remove KHT and, again, you are removing HT-. In order to maintain equilibrium H2T shifts to the right, converting to HT- and H+. This is giving up a hydrogen, decreasing the pH.

Nice analysis.
I always struggle to remember or actually dial into CS, still learning....
What it seems in summary is that for red wines they key to CS is when the pH is just around or above 3.6 in order to drop the acidity in the wine. CS at a lower pH will lower the pH and make the wine more acidic.

Did I miss anything?
 

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How is your Chambourcin, #'s and all?
A neighbor grew these grapes. He basically gave me one day (one evening really) to pick, sandwiched between the big winery coming through with their machine picker and a son's wedding they had planned at the vineyard!

So I started at 3.01 and TA of 8.5. Preferment I adjusted to pH 3.55. Two day cold soak. Oaked during MLF. Post AF and MLF I'm at 3.59; I have not retested the TA.

I'm pretty darn happy with this wine. It's fruity enough, but really it's earthy, like smelling fresh mushrooms. What I'm thinking right now is after bulk aging, I'll bottle some straight, then also blend some with a Syrah that I have which wound up being somewhat light and uber-fruity.
 

Tnuscan

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Nice analysis.
I always struggle to remember or actually dial into CS, still learning....
What it seems in summary is that for red wines they key to CS is when the pH is just around or above 3.6 in order to drop the acidity in the wine. CS at a lower pH will lower the pH and make the wine more acidic.

Did I miss anything?
Yes I believe your right. The thing that confused me is adding Potassium BiCarbonate to raise the pH, but then the instructions suggest to Cold Stabilize, which lowers the acid.

So it must affect the TA numbers more than the pH numbers.

Is this correct?
 

geek

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Yes I believe your right. The thing that confused me is adding Potassium BiCarbonate to raise the pH, but then the instructions suggest to Cold Stabilize, which lowers the acid.

So it must affect the TA numbers more than the pH numbers.

Is this correct?
That's another twist.
We add potassium bicarbonate to raise the pH on acidic wines but this requires CS and not sure what would happen if the pH was below the threshold of 3.6x after the addition of the potassium bicarbonate.
 

Tnuscan

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A neighbor grew these grapes. He basically gave me one day (one evening really) to pick, sandwiched between the big winery coming through with their machine picker and a son's wedding they had planned at the vineyard!

So I started at 3.01 and TA of 8.5. Preferment I adjusted to pH 3.55. Two day cold soak. Oaked during MLF. Post AF and MLF I'm at 3.59; I have not retested the TA.

I'm pretty darn happy with this wine. It's fruity enough, but really it's earthy, like smelling fresh mushrooms. What I'm thinking right now is after bulk aging, I'll bottle some straight, then also blend some with a Syrah that I have which wound up being somewhat light and uber-fruity.
I must be understanding the rise in pH wrong from reading and trying to figure it out. 3.55 to 3.59 after AF and MLF? Is this the norm on most wine from grapes?
 

Stressbaby

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I must be understanding the rise in pH wrong from reading and trying to figure it out. 3.55 to 3.59 after AF and MLF? Is this the norm on most wine from grapes?
Correct. I haven't done enough MLF to know if that is the norm. Interesting also to note that post AF, pre MLF the pH was 3.41. So it dropped a little with AF and rose again with MLF. Degassing might also play a role here too.
 

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