"pp" > wrote in message
om...
> Hi:
>
> I've been having a pretty consistent problem with titrating white
> juice before fermentation, adding tartaric acid based on the results,
> and then titrating after fermentation that the TA level is way too
> high. Latest example: Pinot Blanc juice measured at 4g/L, acid added
> to raise to 6.5g/L, now measured at 8g/L after relatively cold (around
> 15C) fermentation. I really don't know what's going on because:
> - I'm using the same method (pH meter to 8.2) before and after
> fermentation;
> - the juice is fresh, so all acid should be measurable before
> fermentation;
> - it can't be sodium hydroxide losing strength because then the
> measurement would be artificially higher, not lower

Sounds to me like that's _exactly_ what you're seeing. You're getting
higher measurements than you expected.

Still, that's probably not it. I'd guess that you're titrating dissolved
CO2 + TA because you didn't degas the sample. Bring the sample just to the
boiling point to drive off the CO2 before titrating.

Tom S