On Apr 11, 7:43 am, "Franco" > wrote:
> On Apr 10, 10:21 pm, "Dirty Harry" > wrote:
>
> > I have a white Zinfandel that's at about 1.050 and I'd like to stop it there
> > for a sweeter wine. I've read about a few ways to stop it but wonder what's
> > the best. I have potassium sorbate, potassium metabisulfphite, I have a
> > filter, and its about 32f outside right now. I could stop the fermentation
> > by putting it in the cold for a while and then add the sorbate and
> > metabisulphite and then filter? I'd like to use as little chemicals as
> > possible. Thanks guys.
>
> Dirty Harry:
>
> Depending on how big your container is, it could take a long time to
> get down to 32 °F, so that's a consideration. Regarding your desire to
> use as little chemical as possible, there is a usual dosage of sorbate
> that most people use, but I found an article that gives a table of the
> dosage needed based on alcohol %. Obviously, the higher the alcohol%,
> the lower amount of sorbate needed. Here is the link:
>
> http://www.bcawa.ca/winemaking/sorbate.htm
>
> 10%: 200 mg/l
> 11%: 170 mg/l
> 12%: 135 mg/l
> 13%: 100 mg/l
> 14%: 70 mg/l
>
> The above numbers are assuming that the levels of SO2 and pH are
> correct (whatever that means). The threshold for detecting the
> geraniol smell is 182 mg/l. Another source that I found is Margalit,
> who says to use at least 200 PPM of sorbate, and then points out that
> the smell threshold is 150 PPM.
>
> In your case, since you are at 1.05, and assuming that you started at
> 1.09, then you would have a pretty low alcohol content, which would
> mean that you're gonna have to use a lot of sulfite and sorbate.

Just some clarifications - geraniol smell only develops if a sorbated
wine goes through a malolactic fermentation, that should not be an
issue if the wine is properly sulfited. As I recall the article with
the table, one major assumption was that the yeast population is low,
and that's not the case for an active fermentation.

For the past 2 years, I've been making off-dry and sweet wines using
this method and as Steve pointed out, it's way harder than fermenting
to dryness and then back-sweetening. The method I've been using is to
use the cold outside temperatures to stop the active ferment, wait
until most of the yeast drops down, then rack and sulfite and fine at
the same time with bentonite and Sparkalloid, keeping the wine as cool
as possible all the time. Finally, I filter and add the preservative -
sorbate last year and benzoate this year. After all this, I'm finding
that when I bring the wine back to room temperature, there is still
some yeast activity. Last year I dealt with it by re-filtering but the
wine is lacking in aroma, so I'll probably just add some sorbate this
year again - so after all the trouble, I'm basically at square one. I
think I'll go back to back-sweetening next year.

Lastly, 1.050 seems awfully high for a white Zinfandel, that's more
residual sugar than most dessert wines have! Your alcohol levels will
be low and because of that the wine will be in more danger of
spoilage. If you really want it that sweet, I'd highly recommend
fermenting to get at least 10-12% of alcohol and then adding sugar or
sugar syrup.

Pp