I've always tested my red musts immediately after crush. While the SG, Brix, and pH tests seem to be valid, I'm starting to question my TA tests. I'm getting levels that seem too low (i.e. .30 or .40) when the pH's are in a good range. Then, when I wait a few days, the levels are often higher.
What do you do? Do you find that the TA's rise as the grapes break down? Perhaps there's tartaric acid in the skins that isn't assayed immediately after I crush the grapes? Lee
After fermentation starts, I believe the CO2 in the must contributes to TTA. You have carbonic acid or some such thing.
No, I can understand that....but I'm talking about IMMEDIATELY after the crush. I got a level of .35 on syrah grapes that should be just fine. The pH was in a good range. Something is screwy...I suspect that really fresh juice is not representative of the whole grape.
Lee
I don't think the skins have anything to do with it. It's normal for the TA to increase post fermentation, there are some other acids present that are byproducts of fermentation like acetic, succinic etc. I'm pretty sure the rough guess value is a 1 to 1.5 g/l rise. What wat the pH? Maybe you had a high proportion of tartaric to malic if the pH was normal but TA low. Were the grapes really ripe? TA falls the grapes reach ripeness. Joe
I'm with you on this. I've also seen this on fresh juice - Riesling that measured arounf 6g/L jumped to more than 10g/L after fermentation. At the levels you're getting (0.3-0.4) you should be able to do a taste check - if the juice doesn't taste flabby, you've got a measuring error.
Pp
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