"pp" > wrote in message
om...
> "Lum" > wrote in message news:<uutAc.480> >
> > > Ar a recent talk, a professional winemaker here from BC mentioned that
> > > they were getting higher alcohol levels for the starting Brix than
> > > they used to, often by 1% or even more. She said this was confirmed by
> > > other winemakers from the area. Her hypothesis was that the yeast were
> > > getting more efficient in alcohol production. This could have large
> > > repercussions if that were indeed the case. I'm wondering if this is
> > > happening in other, hotter areas, as well?
> > >
> > > Pp
> > > Vancouver, Canada
> >
> > Some types of wine yeast produce more alcohol than others, so the above
> > situation certainly seems possible. But, I don't understand what the
"large
> > repercussions" would be.
> > Lum
> > Del Mar, California, USA
>
> Well, if the yeast got consistenly more efficient in producing
> alcohol, then the winemaking practice would have to adjust to that
> somehow, particularly in hot areas, otherwise we'd end up with hot,
> unbalanced wines, no? 1% is a lot as an average change.
>
> I believe she's been using the same yeast over the years, so it's not
> a change in the type of yeast.
>
> Pp
> Vancouver, BC, Canada

Hi Pp

I suspect that this is nothing more than another case of _misapplying_
that same old end alcohol formula that pops up every now and then.
Using this formula will _always_ produce answers that are 1-2%abv
*too high* !! Let me give an example of this:

We start a ferment with an OG of 1.090 (22BRIX/12PA). We
ferment it down to an EG of 0.990. If we then use that end alcohol
formula, it will _try_ to tell us that we have 13.4%ABV in our wine,
which of course is wrong.

Earlier in this thread, Andy gave us a definition of PA:
"...PA is Potential Alcohol, an estimate of the alcohol content if all of
the sugar is consumed. If any sugar is left in the must, you will not
reach this potential..."

Thus - Our original PA was 12. All of the sugar is consumed in
producing that 12%ABV. With no more sugar to consume, our
ferment comes to a halt, and there is _no way_ we can reach
13.4%ABV in that wine.

It's all very simple. Really !! Tell that lady she hasn't discovered a
mutated strain of yeast, she is only MISapplying that method of
determining end alcohol. If she doubts this, she can easily pay a
lab to test the wine to be sure. HTH

Frederick