Ray's completely correct here, the alcohol tolerance is based on a whole
heap of variables.

To guarantee the yeast you are using is the only yeast you would have to
sterilise (not just sanitise) everything, i.e. steam everything used and
pasteurise/sterile filter the juice. Otherwise the wide variety of yeasts
that are ever present may provide something with a much higher capacity to
ferment than your chosen yeast.

For example, in every winery I have worked in the indigenous yeasts have had
capability to ferment just about anything with sugar (you would assume that
the yeast population over the years gets slanted towards yeasts with some
extreme fermentation properties). We once had some juice stored at 0 deg C,
which started with plenty of free SO2 that started fermenting (we negelcted
to keep checking the FSO2, lesson learnt!).

We also had a case of a yeast contaminating our Sauternes style wine in
barrel. This yeast was quite happy chewing away at the malic acid in the
wine, not the sugars! It took us a long time to figure out what was going
on, the wine was cloudy and fizzy and looked to be sugar fermenting, but the
Baume wasn't dropping. We had to pull it all from barrel and sterile filter
it.

Nature always has a way of mucking your plans up!

Rob L
"Ray" > wrote in message
om...
> Alcohol tolerance for a yeast is an average, not a tolerance. In general
> the yeast will quit at about a given point. But there could be (likely to
> be) yeast in the batch that have a higher tolerance than the average.
There
> could even be some that quit at about the tolerance and then wake up
hungry
> later. There are millions or even billions of yeast in a ferment and some
> of them will be radicals. Also, yeast are not very bright. They don't
> always understand how they are suppose to behave. You could even get a
> whole generation that are lazy and quit early. Use the tolerance as a
guide
> but not as a target.
> ;o)
> Ray
>
> "Art Schubert" <na> wrote in message
> ...
> > Sounds definitive. Thanks. I'll file it away for reference.
> >
> > I'm still curious about whether a yeast with modest alcohol tolerance
> > can possibly do any damage if bottled at or near its alcohol limit
> > with residual sugar but without filtration.
> >
> > a.
> >
> > On Thu, 11 Dec 2003 16:57:19 GMT, "Lum" >
> > wrote:
> >
> > >STERILE FILTRATION-SCIENCE VS MYTH
> >
> > <snip>
>
>