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Acid overdose...tartaric that is.

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NorCal

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Going into season #6. @4score and I are going back to one of our favorites; Cabernet Franc. Besides making some good wine, we have excellent access to the grapes and it is “only” $1,500 per ton. Combined we are doing 2 tons.

Here is the thing with our AVA, which is an hour or so from one of the most ideal places in the world to grow grapes: Napa. While we share the hot days, our Sierra Foothills location does not get the cool ocean breeze at night, which serves to retain the acidity in the grapes. (Our grapes also cost 4X less)

I can map out the rise of brix and the fall of acidity in the Cab Franc vineyard, pretty acurately, as I’ve made at least a little Cab Franc 4 of the last 5 years.
23 brix - 3.5
24 brix - 3.6
25 brix - 3.7
26 brix - 3.9
27 brix - 4.1

Here is the dilemma. We made low brix Cab Sauv last year and we are both going to leave it in the barrel for another year. I’d like a big Cab Franc to potentially blend with it, it it doesn’t come around on its own. So I’ll be looking for 26 brix fruit, but would like the pH in the 3.6 area. The most I’ve adjusted in the past has been .2 pH and the must bounced back to what it was.

I’ve heard that around 3.65 is the tipping point, where acidity will overcome any must buffering capacity and retain the added acid. I’ve heard pHD’s say that you cannot add too much acid pre-ferment, because the excess acid will all fall out. To adjust the acidity from 3.9 to the 3.65, I would need to add between 3-4 pounds of tartaric per ton...A LOT of acid.

With having that much time and money tied up in the grapes, I’ve been chicken to add that much due to the fear of making a sour wine. Anyone with experience in this area?

E4F69499-68D9-446E-BDEF-F1976D214769.jpeg
 

Johnd

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I've been making high BRIX / low acid wines from CA as well, and notice the same trends you indicate in your analysis, 3.9ish+ pH with TA's under 5 and BRIX over 26 is typical. I've brought my musts down into the 3.6's, only to have them bounce back into the 3.8's after AF/MLF has completed. After some aging time, acid additions have only been successful to a small extent, as they always seem to bounce back up, the wine just seems to have a "memory" for where its pH wants to be, though the TA will stay up a bit. I cannot explain it, but like the pHD's explanation, it seems to make sense from the observations in my wine.

Were I in your shoes, I'd first be really happy (that I could get such great prices on grapes and be so close to the growers), then just be prepared to deal with the probability of the numbers, have the acid on hand to make the adjustments slowly into the 3.6 range. In the end, even with bench trials, I've always been (cautiously) happy with bottling the wines with higher pH's and proper sulfite. Can't really speak about how they'll age since they only have about two years under their belts so far. Seems that a big-bodied, bold red can handle the higher pH's (from a taste standpoint).

As a side thought, since you can have some influence on when your grapes are harvested, have you given thought to asking the grower to pick at 3.6 and adjusting the BRIX instead of trying to adjust the acid?
 

ibglowin

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All I have worked with is high brix, high pH Lodi AVA fruit or worse fruit from down south in Deming, NM where it does cool off at night but each day its 100F (or more) for June, July, August..... Had pH's from 3.5 all the way to 4.0. I have learned to adjust down around .2 pH units and then quit. There is just so much going on during AF that all though it may not be the preferred method you can adjust post AF and it is usually much more straight forward and predictable. MLF is easier on a higher pH wine to boot.
 

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I agree with concern over adding that much at once. My last batch size, roughly 1/2 ton and also high PH, doesn't compare volume wise but I'd add about 1/2 of what you calculate pre ferment and go 1/2 and 1/2 again at 3 and 6 months. Seems really easy to get impatient and over shoot.
 

NorCal

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I agree with concern over adding that much at once. My last batch size, roughly 1/2 ton and also high PH, doesn't compare volume wise but I'd add about 1/2 of what you calculate pre ferment and go 1/2 and 1/2 again at 3 and 6 months. Seems really easy to get impatient and over shoot.
I’m reticent to add any acid post fermentation. I’ve done it, but it didn’t seem to achieve what I was looking for; pH didn’t drop much, but the acid came in really strong to the taste.
 

NorCal

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As a side thought, since you can have some influence on when your grapes are harvested, have you given thought to asking the grower to pick at 3.6 and adjusting the BRIX instead of trying to adjust the acid?
I found that the flavor profile from the phenolic development of the grape, especially for Cab Franc, really changes between 23 and 26 brix. Lighter wine, raspberry and cherry notes vs. darker color with blackberry.
 

balatonwine

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Are you selling your wine, thus picking late and adding C4H6O6 rather than simply picking early and adding C12H22O11?

Footnotes:

C4H6O6 = Tartaric acid
C12H22O11 = Sucrose
 

Johnd

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I found that the flavor profile from the phenolic development of the grape, especially for Cab Franc, really changes between 23 and 26 brix. Lighter wine, raspberry and cherry notes vs. darker color with blackberry.
Understood, ripe grapes and tannins are higher on my list as well, that’s why I keep getting those grapes.
 

sour_grapes

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Thanks for the replies. I found the podcast I was referring to. Skip to 7 minutes. A must listen to for high pH winemakers.
https://static1.squarespace.com/static/55daa145e4b0147ff5549674/t/5a7c00a0c830257a7b1490e3/1518076426283/pH+and+TA+Complete.mp3/original/pH+and+TA+Complete.mp3
Thanks for that; very interesting.

I'll admit that it's tough for us mortals to reconcile his two main messages:
-It is most important to adjust the must for pH, whereas TA essentially doesn't matter.
-Changing pH doesn't affect the taste; only TA changes the taste.
 

mainshipfred

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A professional winemaker once told me he pays no attention to the TA with a few exceptions such as wanting a more buttery Chardonnay where he would want to add more malic. Unless we send samples to a lab I don't think home winemaker have the ability to measure the individual percentages of the different acids.
 

zadvocate

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Insidewinemaking podcast had the winemaker for Sebastiani who talks about adding acid pre ferment to bring ph to 3.63. In your case he would make the add. It’s a good listen
 

balatonwine

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I found that the flavor profile from the phenolic development of the grape, especially for Cab Franc, really changes between 23 and 26 brix. Lighter wine, raspberry and cherry notes vs. darker color with blackberry.
The problem is that, as others in the know have already informed you, trying to manipulate acidity is at some point not really effective. A primer Cab Franc that can hang on the vines to get the phenolic development you wish has to be in an environment that does not upset the acidity too much. It all comes down to Terroir. Your grape source does not have the Terroir to create the wine you want. It has its own Terroir.

To create the wine type you wish, you will probably have to compromise. Pick at a time that allows some phenolic development, but at a point that allows you to successfully adjust both sugar and acidity to your ideal.

Well, either that or become a master cellar chemist. But I think that would be cost prohibitive for the amount you are processing. :)
 

Stressbaby

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Thanks for that; very interesting.

I'll admit that it's tough for us mortals to reconcile his two main messages:
-It is most important to adjust the must for pH, whereas TA essentially doesn't matter.
-Changing pH doesn't affect the taste; only TA changes the taste.
It took me 6 years of winemaking to grasp this.
pH ~ microbiology
TA ~ taste
 

mainshipfred

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I attended a seminar on Cab Franc last night with a local winemaker. Coincidentally he touched on TA and ph in general. He is the third winemaker that told me winemakers do not concern themselves with TA. Ph is the only measure they are concerned with. Ph tells you how much acid is in the wine and TA indicates the strength of the acid in the wine. It's not necessarily the overall strength but the strength of the individual acids that affect the taste. Two wines with the same and same ph and TA from different areas and picked at different rpieness and maturity would taste different based on the percentages of the individual acids. Which as Balatonwine said is a product of Terrior. I imagine you could do bench trials using the different individual acids as different acids will change the taste but this would more then likely have to be done post fermentation. IMHO home winemakers have the ability to measure TA but it is a wasted step since we don't have the means and/or measures to go beyond that step.
 

pgentile

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Very interesting thread. It has lifted some of the fog in my mind on the pH/TA subject.
 

Boatboy24

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Ph is the only measure they are concerned with. Ph tells you how much acid is in the wine and TA indicates the strength of the acid in the wine.
I think you have that flipped. I thought TA was 'how much' (g/L) and pH is the 'strength'.
 

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