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.


(LG1111) wrote in message ...
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 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

(LG1111) wrote in message ...
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


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