When to Test/Adjust Wine Acidity

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Mar 29, 2009
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I just purchased an Acid Titration Kit. I have seen all kinds of posts and discussion on checking/adjusting acidity, but haven't read when you test the wine. When is it too late to test/adjust the acidity of a wine? I believe that last years concord grape batch did not have the proper acid levels (kind of a bite/zing to it). I have a grapefruit wine that is about 6 months old and is very tart, can it be adjusted (I haven't checked the acid level yet)? I now have a blackberry/grape concentrate 3 days in the primary and am wondering when to check it's acidity.

Any advice or help would be greatly appreciated.

You should check it before fermentation because a coreect PH and TA will give you a better fermentation, you should also check after it is done fermenting as the acid levels will be different and may need to be upped a little usually and proper levels at this time mean better tasting wine and also it will be more stable to shelve longer.
Best time to test acidity is when making the must, so before fermentation starts.
Adjusting acids during preparing the must gives the acid time to blend in.

Adjusting acid when fermentation is done and the wine is aging is possible but not the best way to go.

Make sure you measure the right amount of acid you need, dissolve that in a little bit of wine and add that to your batch. Then stir gently in.

If you add the acid powder to the wine you need to stir vigorously to dissolve them and that will expose the wine to an excess of oxygen.

Also be aware that adding ANY ingredients to a finished wine could make the wine cloudy again and raises the need to give the wine time again to clear.

I wrote 2 tutorials on acid titration on my web-log.
You can find them here:


and here:


Last edited:
Thanks for the replies! That was the info I was looking for. I will check last years batch just to see if it has an acid problem, but won't try to correct. On the current batch that is in the primary for 4 days, I will wait and check prior to putting in the secondary carbouy, and correct if needed.

Thanks again for the help.
Just read your tutorials Luc, and now know that I will have to boil my still fermenting sample before testing. Is there any difference in how to adjust the acidity of a fermenting batch?

I think the main reason for testing acidity after fermentation ends has to do with sulfiting. Someone will correct me if I'm wrong, but I think the more acidic the wine, the less sulfite is needed because the pH makes the k-meta more effective.

The boiling is done to drive off any CO2 gas dissolved into a wine.
CO2 does alter the measurements as it is an acid in itself.

However boiling for too long will evaporate water (ands alcohol in an already fermenting must) and will therefore give inacurate results if too much vapor is driven off.


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