"pp" > wrote in message
om...
> "Lum" > wrote in message
>...
> >
> > Hi Pp,
> > You may not have a measurement error. Acid adjusted, grape
fermentations
> > often measure from 0.5 to 1.5 g/l higher after fermentation because
yeast
> > produces succinic acid during fermentation. If you chill the wine to 32
> > degrees or so for a few days, potassium bitartrate will precipitate out
of
> > the wine and reduce the titratable acid. Sometimes, the drop in TA due
to
> > tartrate precipitation is about equal to the increase in from succinic
acid,
> > and the TA of the cold stabilized wine ends up being just about equal to
the
> > starting TA. See Margalit, Concepts in Wine Chemistry, page 17.
> > lum
>
> Hi Lum:
>
> Thanks a lot for this interesting info. I've always thought the acid
> level is supposed to drop after fermentation by about 0.5g/L on avg.
> So, if I understand this correctly, after cold fermentation, the acid
> can actually move in any direction w.r.t to the starting level,
> depending on the levels of succinic acid generated and bitartrate
> falling out?

Yes. TA can go up, down or stay the same, but not by large amounts (~1 g/l
or so).

>And, does this only apply to juice that has had tartaric
> acid added to it or in general?

Succinic acid production is not very dependent on the amount of tartaric
acid added, but tartrate precipitation will be greater with larger additions
of tartaric acid.

> I'll definitely check out the Margalit reference, only have to hunt it
> down, which will take some time.
>
> Thx,
>
> Pp