Ben, I agree that it is best to have the acid in the must up front so it
all integrates properly, but I don't feel that small adjustments are a
problem at the end and I hate trying to bring it down. I want to be close
but I would rather take it up a bit at the end. I will generally do what I
suggested. I aim low the first time I make a new wine. Keep records and
adjust the amount of acid I add when I make it again. Really, after making
a wine a couple of times, I rarely have to adjust it at the end. Or not
much anyway.

Ray

"Ben Rotter" > wrote in message
om...
> Bob,
>
> > Books on the subject say the must should be ".60-.80% acid as
expressed
> > in tartaric acid". What I'm wondering is if it is better to err on the
high
> > side, as I've read that some acid is metabolized by the yeast so that as
it
> > ferments you have less acid with a less effective/complete fermentation,
OR
> > if running things on the low side is better?
>
> Actually, that depends on the yeast and the environment (e.g. pH,
> nutrients). Yeasts also *produce* acids during fermentation. With
> non-grape wines, the production of acid during fermentation usually
> tends to be *higher* than the metabolism of acid by the yeast (except
> in cases where the yeast is particularly efficient at metabolising
> acids - e.g. strain 71B-1122) plus tartrate precipitation doesn't tend
> to occur unless a significant amount of the acidity in the must was
> tartaric (i.e. by using acid blend or tartaric to acidify the must).
>
> It's highly unlikely that a stuck fermentation would be the result of
> acid *production during fermentation*. However, musts with very low
> pHs tend to assist in causing sticking. (On that, fermentation
> temperature and yeast nutrients are more of an issue.)
>
> Ray suggested the easiest method - to adjust acidity
> post-fermentation. Some winemakers feel that by doing that the acidity
> somehow doesn't "integrate" so well into the wine, others disagree.
> The acidity of the must *can* be adjusted pre-fermentation, by knowing
> roughly where it's at (measuring the TA) and where it will go
> (estimates of acid production during fermentation), a reasonably
> accurate estimate can be made. The TA of the must can then be adjusted
> based on the final level.
>
> > Anyone want to chime in with what percentage of acid, expressed as
> > tartaric, you shoot for? I ask this because I've had a few batches turn
out
> > with plenty of sugar left over. I go for 13% alcohol and wind up with
11%
> > and sweetness to boot.
>
> Where the TA should be pre-fermentation really depends where you want
> it to end up, and that depends on the style of wine. For example, a
> non-tartaric must has TA of 6 g/l (0.6%) and a pH of 3.3. The final
> wine will not go through MLF. It's desired to have a final level of 6
> g/l. Estimated TA increase during fermentation is 2 g/l. Thus, the
> must's TA will need to be dropped by 2 g/l (chemical deacidification).
> Alternatively, a yeast strain like 71B-1122 or MLF could be used.
>
> Ben
>
> Improved Winemaking
> http://members.tripod.com/~BRotter/