Measured TA vs. added tartaric acid

[jsiddall]

I made my first batch of frozen grape wine earlier this year. The must was 19 l (5 gal) of California Cabernet Sauvignon which measured at 24.1 brix, TA 5.1 g/l and pH 3.7 before fermentation. I wanted to bring the TA up to about 7.5 g/l so I added 30 g of tartaric acid and started fermenting. Unfortunately after fermenting the TA ended up at 9.3 g/l. Yikes!

The must ended up producing about 11.5 l (3 gal) of wine, and even if all the tartaric acid I added ended up in the wine that should still be just 2.6 g/l. If the TA test measures tartaric accurately the TA should have gone up to 7.7 g/l.

The other possibility is that a significant amount of acid came out of the skins during fermentation. In that case, 9.3 g/l less the 2.6 g/l I added means the wine would have been 6.7 g/l on its own.

Any ideas what happened here?

 

[ibglowin]

One thing you learn real fast when making acid additions is to calculate what you think you need to bring the TA to where you want it and then add ONE HALF what you calculated! You can always add more if needed, much harder to remove it once its in. What is the pH now? Sounds like you my need to cold stabilize and or blend it with something else.

 

[sdelli]

Even though many say to make acid adjustments before primary ferment.... Unless I know I am dealing with grapes with a personality of high ph I always leave it alone! Only adjust sugar for brix in your primary and let it become it's own....

 

[sdelli]

Now.... Do a cold stabilization to get some of that acid out.... What is your ph at?

 

[jsiddall]

pH is currently 3.57. Numbers now are actually about where I wanted them, and it does taste pretty good. There is notable acid but it is not out of whack.

Cold stabilizing will have to wait until winter as I have no way to get it cold enough in the summer. That said I thought cold stabilization was more about aesthetics rather than taste. Will dropping the diamonds make the wine taste different?

In the future I will do as @sdelli said and wait until after fermenting for adjustments. I don't see how there is any benefit to adjusting before.

 

[ibglowin]

Cold Stabilization drops tartaric acid which reduces your TA. Its better to add the acid up front as it has more time to fully incorporate into the wine AND more time to stabilize before bottling.

 

[Boatboy24]

As was said, adjust with half. I even did a 3/4 adjustment on a Viognier last year and ended up having to back sweeten in the end to balance the wine out. Turned out fine, but I hated having to use sorbate.

At 3.57 pH, it sounds like you're OK. But what is the TA? Cold stabilizing will help to drop some of the acid out of suspension.

 

[sdelli]

pH is currently 3.57. Numbers now are actually about where I wanted them, and it does taste pretty good. There is notable acid but it is not out of whack.

Cold stabilizing will have to wait until winter as I have no way to get it cold enough in the summer. That said I thought cold stabilization was more about aesthetics rather than taste. Will dropping the diamonds make the wine taste different?

In the future I will do as @sdelli said and wait until after fermenting for adjustments. I don't see how there is any benefit to adjusting before.

Ya.... it takes a LOT of acid to get young Cab grapes down to a ph of 3.5x.... But you have a lot of time to work the acid out of it....

 

[jsiddall]

I thought I had posted the TA already but I don't see it. Anyway, TA is currently 7.8 g/l which should be pretty close to ideal. Cold stabilization could drop that some more.

I do plan on making another small batch of Cabernet Sauvignon from grapes this fall so I could make that one with lower acidity and then blend the two.

 

[stickman]

It is very difficult to get accurate measurements on frozen must that has just thawed. Sugars and acids separate and stratify during the freezing and thawing process. Samples for measurements should only be pulled after the must is warm and thoroughly mixed.

Your numbers look good; remember that if you conduct a malolactic fermentation, some additional acid will be lost.

 

[sdelli]

It is very difficult to get accurate measurements on frozen must that has just thawed. Sugars and acids separate and stratify during the freezing and thawing process. Samples for measurements should only be pulled after the must is warm and thoroughly mixed.



Your numbers look good; remember that if you conduct a malolactic fermentation, some additional acid will be lost.

Very true! I use frozen must quite a bit in the off season. Because it is hard to read..... I do not read it until it has come out of mlf... Just the sg for alcohol. I do pay more attention to it on fresh grapes though....

 

[jsiddall]

It is very difficult to get accurate measurements on frozen must that has just thawed. Sugars and acids separate and stratify during the freezing and thawing process. Samples for measurements should only be pulled after the must is warm and thoroughly mixed.

Your numbers look good; remember that if you conduct a malolactic fermentation, some additional acid will be lost.

Yes, I thawed and stirred well before taking samples. I also blended and filtered the must to try to get an accurate reading.

Just to be clear MLF seems to be done. The pH was 3.43 and the TA 9.3 g/l before MLF. Now, after a couple of months of MLF, it is pH 3.57 and TA 7.8 g/l.